WorldWideScience

Sample records for crystalline polymer lcp

  1. Effect of organoclay on the orientation and thermal properties of liquid-crystalline polymers

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2007-08-01

    Full Text Available on th Thermal Properties of Liquid-Crystallin Polymers a Introduction Liquid-crystalline polymers (LCP) are well known for their excellent properties, such as high strength and stiffness, low melt viscosity, and their high chemical and thermal...] they confirmed the very high degree of dispersion of organoclay in the LCP matrix, because of the formation of hydrogen bonds between the pendent pyridyl group in the LCP and the hydroxyl group of the surfactant residing at the surface of organoclay...

  2. Long-term evaluation of a liquid crystal polymer (LCP)-based retinal prosthesis

    Science.gov (United States)

    Jeong, Joonsoo; Bae, So Hyun; Seo, Jong-Mo; Chung, Hum; Kim, Sung June

    2016-04-01

    Objective. The aim of this study is to evaluate the long-term reliability of a recently presented liquid crystal polymer (LCP) -based retinal prosthesis in vitro as well as in vivo. Because an all-polymer implant introduces another intrinsic leak type due to gas permeation, for which the traditional helium leak test for metallic packages was not designed to quantify, a new method to investigate its durability is required. Approach. We designed and carried out a series of reliability tests specifically for all-polymer implants by quantitatively investigating moisture ingress through various pathways of the polymer surface, and the polymer-polymer and polymer-metal adhesions. Moisture permeation through the bulk material was estimated by analytic calculation, while water ingress through the adhesively sealed LCP-LCP and LCP-metal interfaces was investigated using the separate parts of an electrode array and a package in an accelerated aging condition. In vivo tests were done in rabbits to examine the long-term biocompatibility and implantation stability by fundus observation and optical coherence tomography (OCT) imaging. Main results. The analytic calculation estimated good barrier properties of the LCP. Samples of the LCP-based electrode array failed after 114 days in 87 °C saline as a result of water penetration through the LCP-metal interface. An eye-conformable LCP package survived for 87 days in an accelerated condition at 87 °C. The in vivo results confirmed that no adverse effects were observed around the retina 2.5 years after the implantation of the device. Significance. These long-term evaluation results show the potential for the chronic use of LCP-based biomedical implants to provide an alternative to traditional metallic packages.

  3. LIQUID CRYSTAL POLYMERS (LCP) USED AS A MACHINING FLUID CD

    Science.gov (United States)

    This interactive CD was produced to present the science, research activities, and beneficial environmental and machining advantages for utilizing Liquid Crystal Polymers (LCPs) as a machine fluid in the manufacturing industry.In 1995, the USEPA funded a project to cut flu...

  4. Liquid Crystal Polymer (LCP) based antenna for flexible system on package (SoP) applications

    KAUST Repository

    Marnat, Loic

    2012-06-01

    The design, fabrication and measurement of a bowtie antenna on a flexible Liquid Crystal Polymer (LCP) substrate is reported in this paper. The antenna is fed by a balun transition which helps improve the gain up to 5.1 dB. The antenna performance is analyzed for both planar and curved substrates. The comparison between simulation and measurements shows a good agreement. This structure can either be used to sense the bending of the substrate or use the bending to tilt the beam. © 2012 IEEE.

  5. EFFECT OF DRAWING ON MORPHOLOGY,STRUCTURE AND MECHANICAL PROPERTIES OF BLENDS OF A LIQUID CRYSTALLINE POLYMER AND MODIFIED POLY(PHENYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    LIU Songlin; SHEN Jingshu

    1997-01-01

    Polymer strands with various draw ratios of a thermotropic liquid crystalline polymer (LCP) and modified poly(phenylene oxide) were prepared by drawing the melts leaving a slit die in open air. The morphology, structure and mechanical properties of the resulting strands were studied as a function of LCP content and draw ratio. It was found that the thermal and mechanical properties of the matrix phase did not change dramatically with the amount of LCP and draw ratio, but the orientation of LCP phase could be increased with draw ratio. The mechanical properties of the strands could be improved by moderately drawing the melts. Wide angle X-ray diffraction suggested that the improvement in tenile strength of the strands was due to the resultant fibrillation of LCP phase and enhanced molecular orientation. Morphological observation indicated that excessive drawing of the strands could lead to the break down of the microfibrils of LCP and thus resulted in the decrease of mechanical strength.

  6. Liquid crystalline order in polymers

    CERN Document Server

    Blumstein, Alexandre

    1978-01-01

    Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

  7. A miniaturized, eye-conformable, and long-term reliable retinal prosthesis using monolithic fabrication of liquid crystal polymer (LCP).

    Science.gov (United States)

    Jeong, Joonsoo; Bae, So Hyun; Min, Kyou Sik; Seo, Jong-Mo; Chung, Hum; Kim, Sung June

    2015-03-01

    A novel retinal prosthetic device was developed using biocompatible liquid crystal polymer (LCP) to address the problems associated with conventional metal- and polymer-based devices: the hermetic metal package is bulky, heavy, and labor-intensive, whereas a thin, flexible, and MEMS-compatible polymer-based system is not durable enough for chronic implantation. Exploiting the advantageous properties of LCP such as a low moisture absorption rate, thermobonding, and thermoforming, we fabricate a small, light-weight, long-term reliable retinal prosthesis that can be conformally attached on the eye-surface. A LCP fabrication process using monolithic integration and conformal deformation was established enabling miniaturization and a batch manufacturing process as well as eliminating the need for feed-through technology. The functionality of the fabricated device was tested through wireless operation in saline solution. Its efficacy and implantation stability were verified through in vivo animal tests by measuring the cortical potential and monitoring implanted dummy devices for more than a year, respectively.

  8. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Penwisa Pisitsak

    2012-01-01

    Full Text Available A thermotropic liquid crystalline polymer (LCP was blended with polycarbonate (PC and multiwalled carbon nanotube (CNT with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950 and Vectra V400P (V400P. The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by melt-blending in a twin-screw minicompounder and then injection molded using a mini-injection molder. The fibrillar domains of LCP were found only in the case of PC/VA950 blend. However, these fibrils turned into droplets in the presence of CNT. It was found that CNT preferentially remained inside the LCP domains as predicted from the value of spreading coefficient. The electrical conductivity showed the following order with the numbers in parenthesis representing the electrical percolation threshold of the compounds: PC/CNT (1% > PC/VA950P/CNT (1% > PC/V400P/CNT (3%. The storage modulus showed improvements with the addition of CNT and VA950.

  9. Effects of hybrid composition of LCP and glass fibres on abrasive wear of reinforced LLDPE

    Indian Academy of Sciences (India)

    S A R Hashmi; Ajay Naik; Navin Chand

    2006-02-01

    The hybrid of liquid crystalline polymer (LCP) fibres and glass fibres (GF) provide a combination of modulus and toughness to semi-crystalline linear-low-density-polyethylene (LLDPE). LCP and GF fibres reinforced composites were studied using two-body abrasion tester under different applied loads. Two sets of fibre reinforced LLDPE, 10 and 20 vol%, were investigated. The contents of LCP and glass fibres were varied as 25, 50, 75 and 100 vol% of overall volume of fibres in LLDPE. The effect of replacing glass fibre with LCP fibre on wear is reported. Wear loss increased with the applied loads and glass fibre contents in LLDPE. The replacements of glass fibres with LCP fibres improved abrasive wear resistance of composite. The composite containing 20 vol% of glass fibres in LLDPE showed the specific wear rate nearly double to that of LCP fibre reinforced LLDPE. Incorporation of LCP fibre improved wear resistance of glass fibre reinforced LLDPE. Worn surfaces were studied using SEM. Glass fibres were broken in small debris and removed easily whereas LCP fibres yielded to fibrillation during abrasive action. The overall wear rate was governed by the composition and test conditions.

  10. COLD DRAWING IN CRYSTALLINE POLYMERS

    Science.gov (United States)

    alcohols, phenol) in Nylon 6 produced changes in the crystalline structure as well as plasticizer action; these two effects must therefore be carefully...distinguished. Changes in the crystalline structure were followed by changes in the infrared spectrum. Dynamic mechanical and thermogravimetric analysis

  11. Liquid crystalline polymer nanocomposites reinforced with in-situ reduced graphene oxide

    Directory of Open Access Journals (Sweden)

    D. Pedrazzoli

    2015-08-01

    Full Text Available In this work liquid-crystalline polymer (LCP nanocomposites reinforced with in-situ reduced graphene oxide are investigated. Graphene oxide (GO was first synthesized by the Hummers method, and the kinetics of its thermal reduction was assessed. GO layers were then homogeneously dispersed in a thermotropic liquid crystalline polymer matrix (Vectran®, and an in-situ thermal reduction of GO into reduced graphene oxide (rGO was performed. Even at low rGO amount, the resulting nanocomposites exhibited an enhancement of both the mechanical properties and the thermal stability. Improvements of the creep stability and of the thermo-mechanical behavior were also observed upon nanofiller incorporation. Furthermore, in-situ thermal reduction of the insulating GO into the more electrically conductive rGO led to an important surface resistivity decrease in the nanofilled samples.

  12. Phase diagrams of binary crystalline-crystalline polymer blends.

    Science.gov (United States)

    Matkar, Rushikesh A; Kyu, Thein

    2006-08-17

    A thermodynamically self-consistent theory has been developed to establish binary phase diagrams for two-crystalline polymer blends by taking into consideration all interactions including amorphous-amorphous, crystal-amorphous, amorphous-crystal, and crystal-crystal interactions. The present theory basically involves combination of the Flory-Huggins free energy for amorphous-amorphous isotropic mixing and the Landau free energy of polymer solidification (e.g., crystallization) of the crystalline constituents. The self-consistent solution via minimization of the free energy of the mixture affords determination of eutectic, peritectic, and azeotrope phase diagrams involving various coexistence regions such as liquid-liquid, liquid-solid, and solid-solid coexistence regions bound by liquidus and solidus lines. To validate the present theory, the predicted eutectic phase diagrams have been compared with the reported experimental binary phase diagrams of blends such as polyethylene fractions as well as polycaprolactone/trioxane mixtures.

  13. Mechanism Studies of LCP Synthesis

    Directory of Open Access Journals (Sweden)

    Anne Buyle Padias

    2011-05-01

    Full Text Available The LCP (Liquid Crystal Polymer known as Vectra is synthesized by acidolysis of 4-hydroxybenzoic acid with 6-hydroxy-2-naphthoic acid. The apparently simple acidolysis mechanism for LCP polycondensation is in fact a complex blend of mechanisms. Kinetics of model reactions and of actual polycondensations followed second-order kinetics and their rate constants were comparable. In the latter stages, ketene loss leads to phenolic ends, while decarboxylation provides phenyl ester ends. Accordingly, the mechanism changes to phenolysis. A quinone methide intermediate may also intervene, as revealed by kinetics studies and MALDI-TOF spectroscopy. Tailor-made matrices and synthesis of alternating well-defined oligomers assisted our studies. Nucleophilic aromatic substitutions may play a role, and we speculate on possible chain polycondensation. Esterolysis may be a useful alternative to LCP synthesis. Complications caused by ketene loss can be averted by the use of methoxycarbonyloxy monomers.

  14. Miscibility of Semi-flexible Thermotropic Liquid Crystalline Copolyesteramide with Polyamide 66

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by usingaBrabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction) of p-amino benzoic acid (ABA)and 70% (molar fraction) of poly (ethylene terephthalate)(PET). The LCP/PA66 blends wereinvestigated in terms of the thermal and dynamic mechanical properties. It was found that PA66and LCP components of the blends are miscible in the molten state, but are partially miscible inthe solid state. The inclusion of the semi-flexible LCP into PA66 retards the crystallization rateof PA66. Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.

  15. LAMELLAR STRUCTURE OF THERMOTROPIC LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    CHEN Shouxi; JIN Yongze

    1994-01-01

    The lamellar structure of a thermotropic aromatic polyester with flexible spacer has been studied by using transmission electron microscopy. It was found that the lamellar structure could be observed in the crystalline samples ofthis semirigid polymer crystallized from different states. The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymers of flexible chain molecules. The molecular chains in the lamellae are oriented in the thickness direction as determined by electron diffraction. The possibility of molecular chains folding in the lamellae has been discussed.

  16. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  17. CFRP materials reinforced with LCP fibres for applications in vehicle and aircraft engineering. Final report; Faserverbundkunststoffe mit einer LCP-Faserverstaerkung fuer Anwendungen im Fahrzeug- und Flugzeugbau. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-11

    CFRP materials reinforced with liquid crystalline polyester (LCP) fibres were produced and characterized with regard to their physical and mechanical characteristics. Compared with non-reinforced plastics, polypropylene/LCP fibre-UD laminates produced by filmstacking, epoxy resin/LCP fibre-UD laminates produced by spooling and epoxy resin composites with internal LCP fibre fleece had significantly higher strength and stiffness as well as high thermoforming resistance and waterproofness. [Deutsch] In diesem Forschungsvorhaben wurden Faserverbundkunststoffe mit einer Verstaerkungsfaser auf Basis eines thermotropen fluessigkristallinen Polyester [Liquid Crystalline Polyester, abgekuerzt LCP] hergestellt und bezueglich der physikalisch-mechanischen Eigenschaften charakterisiert. Die im `filmstacking`-Verfahren hergestellte Polypropylen/LCP-Faser-UD-Laminate und mittels Bewicklung gewonnene Epoxidharz/LCP-Faser-UD-Laminate sowie Epoxidharzverbunde mit eingearbeiteten LCP-Faservlies zeigen gegenueber den unverstaerkten Kunststoffmaterialien einen betraechtlichen Anstieg von Festigkeit und Steifigkeit. Die Faserverbunde weisen ausserdem eine hohe Waermeformbestaendigkeit und Wassersperrwirkung auf. (orig.)

  18. Dynamic control of crystallinity in polymer film casting process

    OpenAIRE

    Thananchai Leephakpreeda

    2005-01-01

    This paper presents an approach for dynamic control of crystallinity in polymer film casting process. As known, the transients of crystallization dictate the microstructures of semi-crystalline polymer during solidification. In turn, the properties of finished products can be determined by adjustable variables in polymer film casting process such as temperature of chill roll. In this work, an experimental model of the solidification in film casting process is derived by a system identificatio...

  19. Integrated microsystems packaging approach with LCP

    Science.gov (United States)

    Jaynes, Paul; Shacklette, Lawrence W.

    2006-05-01

    Within the government communication market there is an increasing push to further miniaturize systems with the use of chip-scale packages, flip-chip bonding, and other advances over traditional packaging techniques. Harris' approach to miniaturization includes these traditional packaging advances, but goes beyond this level of miniaturization by combining the functional and structural elements of a system, thus creating a Multi-Functional Structural Circuit (MFSC). An emerging high-frequency, near hermetic, thermoplastic electronic substrate material, Liquid Crystal Polymer (LCP), is the material that will enable the combination of the electronic circuit and the physical structure of the system. The first embodiment of this vision for Harris is the development of a battlefield acoustic sensor module. This paper will introduce LCP and its advantages for MFSC, present an example of the work that Harris has performed, and speak to LCP MFSCs' potential benefits to miniature communications modules and sensor platforms.

  20. Dynamic control of crystallinity in polymer film casting process

    Directory of Open Access Journals (Sweden)

    Thananchai Leephakpreeda

    2005-05-01

    Full Text Available This paper presents an approach for dynamic control of crystallinity in polymer film casting process. As known, the transients of crystallization dictate the microstructures of semi-crystalline polymer during solidification. In turn, the properties of finished products can be determined by adjustable variables in polymer film casting process such as temperature of chill roll. In this work, an experimental model of the solidification in film casting process is derived by a system identification technique. This model is used to design a digital feedback controller including a state estimator. The simulation results show the effectiveness of the proposed control technique on an extruded film.

  1. ELECTROCHROMETIC STUDIES ON POLAR MULTILAYERS OF LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    GONG Mingxuan; REN Yanzhi; LIU Wang; GAO Manglai; ZHAO Yingying; BAI Yubai; LI Tiejin

    1995-01-01

    Electrochrometic measurements were carried on the Z-type Langmuir-Blodgett films oftwo liquid crystalline polymers: mono- {6-[4-(phenylazo) naphthyloxy] hexyl } (1a) andmono- { 6-[4- (anthraquinone-1-azo) naphthyloxy] hexyl} (2a) ester of polymaleic acid . Itwas found that for both polymers, poling fields parallel and antiparallel to dipole momentsof the polymer side chains induce red and blue shift in absorption bands, respectively. Forpolymer la blue shift is accompanied by absorbance increase, while red shift by absorbancedecrease;but for polymer 2a only decrease in absorbance is observed. A simple model wasproposed to analyze the results.

  2. STUDY ON INTERMITTENT SHEAR FLOW AND RELAXATION BEHAVIOR OF THERMOTROPIC LIQUID CRYSTALLINE POLYMER

    Institute of Scientific and Technical Information of China (English)

    Ruo-Bing Yu; Chi-Xing Zhou; Wei Yu

    2005-01-01

    Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation after cessation of shear flow was used to study the rheological behavior and internal structure of thermotropic liquid crystalline polymer (TLCP). There are two kinds of intermittent shear flow: all start-up flows are in the same direction (intermittent flow forward: IFF) and start-up flows change their directions alternately (intermittent flow reversal: IFR). The results show that the stress of start-up flow of IFF and IFR in the test process is not superposed, indicating different changes of internal structure of thermotropic LCP (TLCP). Two main factors affect structure changes in the experimental time scale. One relates to long-term texture relaxation process, the other is an interchain reaction that becomes important after 30 min. The two factors raise the stress of IFF, but express complex effects for the stress of IFR. The latter factor becomes very important at long time annealing process. The relaxation behavior was also studied by the application of wide range relaxation spectrum calculated from the combined dynamic modulus, which gave three characteristic relaxation times (0.3, 10 and 600 s)ascribable to the relaxations of less-phase orientation, domain orientation, and domain deformation, respectively. The result also shows that the domain coalescence (texture relaxation), a long relaxation time, is a much slow process and lasts beyond 2400 s of the test time.

  3. Electronic and optical excitations in crystalline conjugated polymers

    Science.gov (United States)

    van der Horst, J.-W.; Bobbert, P. A.; Michels, M. A.

    2002-07-01

    We calculate the electronic and optical excitations of crystalline polythiophene and polyphenylenevinylene, using the GW approximation for the electronic self-energy and including excitonic effects by solving the electron-hole Bethe-Salpeter equation. We compare with our earlier calculations on an isolated polythiophene chain and polymer chains embedded in a dielectric medium. Surprisingly, we find for the crystalline calculations optical gaps and exciton binding energies that are significantly smaller than present experimental values. We attribute the disagreement to the fact that the quantum-mechanical coherence between polymer chains, present in the calculations, is absent in most experimental situations. We discuss possible reasons for this absence. Our general conclusion is that the picture of a polymer chain in a dielectric medium is most appropriate in describing the present experimental data on electronic and optical excitations in conjugated polymers.

  4. Liquid crystalline thermosetting polymers as protective coatings for aerospace

    NARCIS (Netherlands)

    Guerriero, G.L.

    2012-01-01

    Environmental regulations are driving the development of new aerospace coating systems, mainly to eliminate chromates and reduce volatile organic compound (VOC) emissions. Among the various potential options for new coating materials, liquid crystalline polymers (LCPs) are attractive due to their un

  5. High Q, Miniaturized LCP-Based Passive Components

    KAUST Repository

    Shamim, Atif

    2014-10-16

    Various methods and systems are provided for high Q, miniaturized LCP-based passive components. In one embodiment, among others, a spiral inductor includes a center connection and a plurality of inductors formed on a liquid crystal polymer (LCP) layer, the plurality of inductors concentrically spiraling out from the center connection. In another embodiment, a vertically intertwined inductor includes first and second inductors including a first section disposed on a side of the LCP layer forming a fraction of a turn and a second section disposed on another side of the LCP layer. At least a portion of the first section of the first inductor is substantially aligned with at least a portion of the second section of the second inductor and at least a portion of the first section of the second inductor is substantially aligned with at least a portion of the second section of the first inductor.

  6. Polymer Morphology and Crystallinity close to Inorganic Surfaces

    Science.gov (United States)

    Chrissopoulou, Kiriaki; Papananou, Hellen; Anastasiadis, Spiros H.; Andrikopoulos, Konstantinos S.; Voyiatzis, George A.

    2015-03-01

    Polymer behavior close to surfaces or when restricted in space can be very different from that in the bulk. In this work, we investigate the morphology, crystallization and chain conformation of a hydrophilic, semi-crystalline polymer, poly(ethylene oxide), PEO, when mixed with silica, SiO2, nanoparticles in a broad range of compositions. The good dispersion of the nanoparticles was verified by Transmission Electron Microscopy (TEM), whereas the morphology and crystallization behaviour of the hybrids were investigated with, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). A gradual decrease of polymer crystallinity with increasing nanoparticles content is observed; nevertheless, polymer crystallization exists for all silica loadings. Moreover, DSC showed two melting and crystallization transitions in hybrids with polymer content lower than 50wt%, indicating that the polymer crystallizes differently than the bulk when it is in a thin interfacial layer near the silica surface. The existence of the two transitions are also evident in the IR and Raman spectra. Partially sponsored by EU (COST Action MP0902) and by the Greek GSRT (Research Funding Program: ARISTEIA II (SMART-SURF, project No. 3393, 2013SE01380048).

  7. One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Larsen, Niels Bent

    2013-01-01

    The non-specific adsorption of dissolved analytes strongly reduces the sensitivity and reliability in polymer microanalytical systems. Here, a one-step aqueous phase procedure modifies polymer material surfaces to strongly reduce their non-specific adsorption of a broad range of organic analytes ...... systems, including polystyrene (PS), cyclic olefin copolymer (COC), liquid crystalline polymer (LCP), and polyimide (PI)....

  8. Piezoelectric and pyroelectric effects of a crystalline polymer

    Science.gov (United States)

    Kundu, Nikhil K.; Kundu, Malay

    1990-01-01

    Polyvinylidene flouride (PVDF) is a crystalline polymer to both piezoelectric and pyroelectric nature. Piezoelectricity produces electrical signals when mechanically deformed, and pyroelectricity is the electrical polarization induced by thermal absorption in crystals. To demonstrate the piezoelectric effect PVDF is subjected to impact loads which produce electrical charges proportional to mechanical stresses. A heat source was used to demonstrate the pyroelectric nature of PVDF. The rise in temperature due to absorbed energy by the polymer produces electrical output. The qualitative test results obtained are graphically reproduced.

  9. Liquid-crystalline aromatic-aliphatic copolyester bioresorbable polymers.

    Science.gov (United States)

    de Oca, Horacio Montes; Wilson, Joanne E; Penrose, Andrew; Langton, David M; Dagger, Anthony C; Anderson, Melissa; Farrar, David F; Lovell, Christopher S; Ries, Michael E; Ward, Ian M; Wilson, Andrew D; Cowling, Stephen J; Saez, Isabel M; Goodby, John W

    2010-10-01

    The synthesis and characterisation of a series of liquid-crystalline aromatic-aliphatic copolyesters are presented. Differential scanning calorimetry showed these polymers have a glass transition temperature in the range 72 degrees C-116 degrees C. Polarised optical microscopy showed each polymer exhibits a nematic mesophase on heating to the molten state at temperatures below 165 degrees C. Melt processing is demonstrated by the production of injection moulded and compression moulded specimens with Young's modulus of 5.7 +/- 0.3 GPa and 2.3 +/- 0.3 GPa, respectively. Wide-angle X-ray scattering data showed molecular orientation is responsible for the increase of mechanical properties along the injection direction. Degradation studies in the temperature range 37 degrees C-80 degrees C are presented for one polymer of this series and a kinetic constant of 0.002 days(-1) is obtained at 37 degrees C assuming a first order reaction. The activation energy (83.4 kJ mol(-1)) is obtained following the Arrhenius analysis of degradation, showing degradation of this material is less temperature sensitive compared with other commercially available biodegradable polyesters. In vitro and in vivo biocompatibility data are presented and it is shown the unique combination of degradative, mechanical and biological properties of these polymers may represent in the future an alternative for medical device manufacturers.

  10. A NEW STRATEGY FOR THE DESIGN OF LIQUID CRYSTALLINE POLYMERS WITH FLEXIBLE AND APOLAR BUILDING BLOCKS

    Institute of Scientific and Technical Information of China (English)

    K.C. Gupta; H.K. Abdulkadir; S. Chand

    2003-01-01

    The synthesis and characterization of a new series of liquid crystalline polymers, poly(dicycloalkyl vinylterephthalate)s, are reported. The basic building blocks of these polymers are not mesogenic by themselves. However,very stable mesophases can be generated by self-assembly of the polymer molecules. This approach suggests a novel design strategy of liquid crystalline polymers with flexible and apolar building blocks.

  11. Reducing burn-in voltage loss in polymer solar cells by increasing the polymer crystallinity

    KAUST Repository

    Heumueller, Thomas

    2014-08-01

    In order to commercialize polymer solar cells, the fast initial performance losses present in many high efficiency materials will have to be managed. This burn-in degradation is caused by light-induced traps and its characteristics depend on which polymer is used. We show that the light-induced traps are in the bulk of the active layer and we find a direct correlation between their presence and the open-circuit voltage loss in devices made with amorphous polymers. Solar cells made with crystalline polymers do not show characteristic open circuit voltage losses, even though light-induced traps are also present in these devices. This indicates that crystalline materials are more resistant against the influence of traps on device performance. Recent work on crystalline materials has shown there is an energetic driving force for charge carriers to leave amorphous, mixed regions of bulk heterojunctions, and charges are dominantly transported in pure, ordered phases. This energetic landscape allows efficient charge generation as well as extraction and also may benefit the stability against light-induced traps. This journal is © the Partner Organisations 2014.

  12. MORPHOLOGICAL STUDIES OF A THERMOTROPIC SIDE-CHAIN LIQUID CRYSTALLINE POLYMER DURING MESOPHASE TRANSITIONS

    Institute of Scientific and Technical Information of China (English)

    Chi-bing Tan; Quan-ling Zhang; Shu-fan Zhang; Xia-yu Wang; Mao Xu

    1999-01-01

    The morphological features of a side-chain liquid crystalline polymer during the mesophase transitions were investigated by using the DSC technique. The polymer used was polyacrylate with mesogens of three benzene rings attached to the main chain through a flexible spacer. A special two-phase texture was observed in the transition temperature range. Similar to main-chain liquid crystalline polymers the transition process of the side-chain liquid crystalline polymer was composed of an initiation of the new phase at local places of the old phase matrix and a growth process of the new phase domains.

  13. A paint removal concept with side-chain liquid crystalline polymers as primer material

    NARCIS (Netherlands)

    Wielen, van der M.W.J.; Cohen Stuart, M.A.; Fleer, G.J.; Nieuwhof, R.P.; Marcelis, A.T.M.; Sudhölter, E.J.R.

    2001-01-01

    A new paint removal concept is introduced making use of a polymer primer layer with a sharp softening temperature. For this, a new class of side-chain liquid crystalline polymers with polar moieties in the backbone has been developed and studied in thin films. These polymers form lamellar-ordered

  14. H-Bonded Liquid Crystalline Polymer Network Materials

    Institute of Scientific and Technical Information of China (English)

    LIN Hong-Cheu; HENDRIANTO Jemmy

    2001-01-01

    @@Side-chain copolymers, poly(mOBA-co-mStilb)s, composed of proton acceptors (stilbazoles) and proton donors (benzoic acids) connected to polyacrylate backbone with different methylene spacer lengths (m = 6 and 10) were prepared in different donor/acceptor molar ratios. The H-bonded copolymeric networks were formed once they were synthesized, and showed more homogenous phase than the physical-blended supramolecular networks consisting of donor and acceptor homopolymers, i.e.H-bonded blends of PmOBA and PmStilb. In order to compare the effects of the backbone connection of these H-bonded copolymers and blends, we also built monomer-monomer and polymer-monomer H-bonded complexes of similar structures (shown in Fig. 1). DSC, POM, and powder XRD studies reveal that the copolymers (m = 10)with mole fractions of benzoic acids between 0.33-0.83 show the smectic A (SMA) phase with layer spacing values between 42.22A-50.47A (increases with higher H-bonded crosslinking density between benzoic acids and stilbazoles), while for m = 6, liquid crystalline behavior still can be observed at 0.89 molar fraction of benzoic acids. However, on the basis of powder XRD study it is found that the d spacing values of H-bonded copolymers with m = 6 in the SmA phase increase with higher molar ratios of benzoic acids, which is agreed with the formation of microphase separation due to the hydrogen bonds of benzoic acids connected themselves from the same backbone. The isotropization temperatures of the H-bonded copolymers and blends increase as the molar ratios of benzoic acids increase, while the higher crosslinking density of the H-bonded copolymeric networks and blends can stabilize the liquid crystalline phase.

  15. H-Bonded Liquid Crystalline Polymer Network Materials

    Institute of Scientific and Technical Information of China (English)

    LIN; Hong-Cheu

    2001-01-01

    Side-chain copolymers, poly(mOBA-co-mStilb)s, composed of proton acceptors (stilbazoles) and proton donors (benzoic acids) connected to polyacrylate backbone with different methylene spacer lengths (m = 6 and 10) were prepared in different donor/acceptor molar ratios. The H-bonded copolymeric networks were formed once they were synthesized, and showed more homogenous phase than the physical-blended supramolecular networks consisting of donor and acceptor homopolymers, i.e.H-bonded blends of PmOBA and PmStilb. In order to compare the effects of the backbone connection of these H-bonded copolymers and blends, we also built monomer-monomer and polymer-monomer H-bonded complexes of similar structures (shown in Fig. 1). DSC, POM, and powder XRD studies reveal that the copolymers (m = 10)with mole fractions of benzoic acids between 0.33-0.83 show the smectic A (SMA) phase with layer spacing values between 42.22A-50.47A (increases with higher H-bonded crosslinking density between benzoic acids and stilbazoles), while for m = 6, liquid crystalline behavior still can be observed at 0.89 molar fraction of benzoic acids. However, on the basis of powder XRD study it is found that the d spacing values of H-bonded copolymers with m = 6 in the SmA phase increase with higher molar ratios of benzoic acids, which is agreed with the formation of microphase separation due to the hydrogen bonds of benzoic acids connected themselves from the same backbone. The isotropization temperatures of the H-bonded copolymers and blends increase as the molar ratios of benzoic acids increase, while the higher crosslinking density of the H-bonded copolymeric networks and blends can stabilize the liquid crystalline phase.……

  16. Fast Switching of Vertical Alignment Liquid Crystal Cells with Liquid Crystalline Polymer Networks

    Science.gov (United States)

    Baek, Jong-In; Kim, Ki-Han; Kim, Jae Chang; Yoon, Tae-Hoon; Woo, Hwa Sung; Shin, Sung Tae; Souk, Jun Hyung

    2009-05-01

    This paper reports on the electro-optic characteristics of vertical alignment (VA) liquid crystal (LC) cells with liquid crystalline polymer networks. Optical bouncing, that occurs during the turn-on of VA cells, can be eliminated by introducing in-cell polymer networks. Furthermore, the turn-off also becomes much faster because of the anchoring effect caused by the anisotropy in the molecular shape of the liquid crystalline polymers. These response times have been found to vary for different LC/prepolymer mixtures. When the concentration of the liquid crystalline prepolymer in the initial LC/prepolymer mixture was 3, 5, or 10 wt %, the response times were measured to be 34, 56, and 87% faster than those of a VA cell with pure LC. These switching behaviors of VA cells with liquid crystalline polymer networks are demonstrated and compared with those using pure LC and with polymer networks made of isotropic prepolymers.

  17. Supramolecular Polymer Network-Mediated Self-Assembly of Semicrystalline Polymers with Excellent Crystalline Performance.

    Science.gov (United States)

    Cheng, Chih-Chia; Chuang, Wei-Tsung; Lee, Duu-Jong; Xin, Zhong; Chiu, Chih-Wei

    2017-03-01

    A novel application of supramolecular interactions within semicrystalline polymers, capable of self-assembling into supramolecular polymer networks via self-complementary multiple hydrogen-bonded complexes, is demonstrated for efficient construction of highly controlled self-organizing hierarchical structures to offer a direct, efficient nucleation pathway resulting in superior crystallization performance. Herein, a novel functionalized poly(ε-caprolactone) containing self-complementary sextuple hydrogen-bonded uracil-diamidopyridine (U-DPy) moieties is successfully developed and demonstrated excellent thermal and viscoelastic properties as well as high dynamic structural stability in the bulk state due to physical cross-linking created by reversible sextuple hydrogen bonding between U-DPy units. Due to the ability to vary the extent of the reversible network by tuning the U-DPy content, this newly developed material can be readily adjusted to obtain the desired crystalline products with specific characteristics. Importantly, incorporating only 0.1% U-DPy resulted in a polymer with a high crystallization rate constant, short crystallization half-time, and much more rapid crystallization kinetics than pristine PCL, indicating a low content of U-DPy moieties provides highly efficient nucleation sites that manipulate the nucleation and growth processes of polymer crystals to promote crystallization and chain alignment in bulk. This new system is suggested as a potential new route to substantially improve the performance of polymer crystallization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. SYNTHESIS AND PROPERTIES OF NEW MESOGEN-JACKETED LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Qi-ding Mi; Qi-feng Zhou

    2000-01-01

    Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, and mesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of these polymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Their liquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. The results show that 1) a more flexible polymer main-chain is more favorable to the formation of a liquid crystal phase, while 2)a flexible spacer will decrease the "Jacket Effect" and the liquid crystallinity and 3) a subtle modification of the terminal groups on the mesogenic unit may also have a significant influence on properties of the polymers.

  19. High-Field-Effect Mobility of Low-Crystallinity Conjugated Polymers with Localized Aggregates.

    Science.gov (United States)

    Son, Sung Y; Kim, Yebyeol; Lee, Junwoo; Lee, Gang-Young; Park, Won-Tae; Noh, Yong-Young; Park, Chan E; Park, Taiho

    2016-07-01

    Charge carriers typically move faster in crystalline regions than in amorphous regions in conjugated polymers because polymer chains adopt a regular arrangement resulting in a high degree of π-π stacking in crystalline regions. In contrast, the random polymer chain orientation in amorphous regions hinders connectivity between conjugated backbones; thus, it hinders charge carrier delocalization. Various studies have attempted to enhance charge carrier transport by increasing crystallinity. However, these approaches are inevitably limited by the semicrystalline nature of conjugated polymers. Moreover, high-crystallinity conjugated polymers have proven inadequate for soft electronics applications because of their poor mechanical resilience. Increasing the polymer chain connectivity by forming localized aggregates via π-orbital overlap among several conjugated backbones in amorphous regions provides a more effective approach to efficient charge carrier transport. A simple strategy relying on the density of random copolymer alkyl side chains was developed to generate these localized aggregates. In this strategy, steric hindrance caused by these side chains was modulated to change their density. Interestingly, a random polymer exhibiting low alkyl side chain density and crystallinity displayed greatly enhanced field-effect mobility (1.37 cm(2)/(V·s)) compared with highly crystalline poly(3-hexylthiophene).

  20. SYNTHESIS AND CHARACTERIZATION OF TRIAZOLE CONTAINING LIQUID CRYSTALLINE POLYMERS THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Devamani Srividhya; Sundaram Manjunathan; Sivashankaran Nithyanandan; Subramanan Balamurugan; Sengodan Senthil

    2009-01-01

    Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(Ⅰ) yielded target polyesters with 1,2,3-triazole groups. The structure of the polymer was confirmed by spectral techniques. GPC analysis reveals that the polymers have moderate molecular weight with narrow distribution. Hot stage optical polarizing microscopic investigation confirms the liquid crystalline nature of the polymers with lengthy flexible spacers, while the short chain containing polymers does not show the mesomorphic properties. Differential scanning calorimetric analysis confirms the formation of mesophase in some of the polymers, and it is in accordance with the microscopic results. Thermal stabilities of the polymers were analyzed by thermogravimetric analysis.

  1. ADVANCES IN LIQUID CRYSTALLINE POLYESTERS

    Institute of Scientific and Technical Information of China (English)

    W. J. Jackson

    1992-01-01

    Advances have been made in understanding the interactions of composition, molecular weight,liquid crystallinity, orientation, and three-dimensional crystallinity on the properties of injection-molded and melt-spun liquid crystalline polyesters (LCP's). Two classes of potentially low-cost LCP's were compared : (1) semiflexible LCP's prepared from 1,6-hexanediol and the dimethyl ester of either trans-4, 4'-stilbenedicarboxylic acid or 4.4 ′-biphenyldicarboxylic acid and (2) all-aromatic LCP's prepared from terephthalic acid, 2, 6-naphthalenedicarboxylic acid, the diacetate of hydroquinone,and the acetate of p-hydroxybenzoic acid. The effects of composition on the plastic properties of the 4-component all-aromatic LCP's were determined with the aid of a 3 × 3 factorial statistically designed experiment, the generation of equations with a computer program, and the plotting of three-dimensional figures and contour diagrams. The effects of absolute molecular weight (Mw) on the tensile strengths of the semiflexible LCP's and one of the all-aromatic LCP's having an excellent balance of plastic properties were also compared, and it was observed that the semiflexible LCP's required Mw's about 4 times higher than the all-aromatic LCP to attain a given strength. Persistence lengths and molecular modeling were used to explain these differences.

  2. The genomes of the non-clearing-zone-forming and natural-rubber- degrading species Gordonia polyisoprenivorans and Gordonia westfalica harbor genes expressing Lcp activity in Streptomyces strains.

    Science.gov (United States)

    Bröker, Daniel; Dietz, David; Arenskötter, Matthias; Steinbüchel, Alexander

    2008-04-01

    The latex-clearing protein (Lcp(K30)) from the rubber-degrading bacterium Streptomyces sp. strain K30 is involved in the cleavage of poly(cis-1,4-isoprene), yielding isoprenoid aldehydes and ketones. Lcp homologues have so far been detected in all investigated clearing-zone-forming rubber-degrading bacteria. Internal degenerated oligonucleotides derived from lcp genes of Streptomyces sp. strain K30 (lcp(K30)), Streptomyces coelicolor strain A3(2), and Nocardia farcinica strains IFM10152 and E1 were applied in PCR to investigate whether lcp homologues occur also in the non-clearing-zone-forming rubber-utilizing bacteria Gordonia polyisoprenivorans strains VH2 and Y2K, Gordonia alkanivorans strain 44187, and Gordonia westfalica strain Kb1, which grow adhesively on rubber. The 1,230- and 1,224-bp lcp-homologous genes from G. polyisoprenivorans strain VH2 (lcp(VH2)) and G. westfalica strain Kb1 (lcp(Kb1)) were obtained after screening genomic libraries by degenerated PCR amplification, and their translational products exhibited 50 and 52% amino acid identity, respectively, to Lcp(K30). Recombinant lcp(VH2) and lcp(Kb1) harboring cells of the non-rubber-degrading Streptomyces lividans strain TK23 were able to form clearing zones and aldehydes on latex overlay-agar plates, thus indicating that lcp(VH2) and lcp(Kb1) encode functionally active proteins. Analysis by gel permeation chromatography demonstrated lower polymer concentrations and molecular weights of the remaining polyisoprenoid molecules after incubation with these recombinant S. lividans strains. Reverse transcription-PCR analysis demonstrated that lcp(VH2) was transcribed in cells of G. polyisoprenivorans strain VH2 cultivated in the presence of poly(cis-1,4-isoprene) but not in the presence of sodium acetate. Anti-Lcp(K30) immunoglobulin Gs, which were raised in this study, were rather specific for Lcp(K30) and did not cross-react with Lcp(VH2) and Lcp(Kb1). A lcp(VH2) disruption mutant was still able to grow

  3. FROM CRYSTALLINE BLOCK SLIPS TO DOMINANCE OF NETWORK STRETCHING——MECHANISMS OF TENSILE DEFORMATION IN SEMI-CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Y. Men; G. Strobl

    2002-01-01

    The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curves obtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and the amorphous phases. However, the relative weights of the two portions change with the deformation stage. At low deformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows the system to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the force generated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformation mechanism then changes into a disaggregation - recrystallization process.

  4. Demise of the LCP: villain or scapegoat?

    Science.gov (United States)

    MacKintosh, David

    2015-08-01

    The winding down and withdrawal of the Liverpool Care Pathway (LCP) following the Neuberger Report has been met with mixed reviews. It appears that responsibility for failures of clinical care has been laid at the feet of a care pathway rather than the practitioners who used it, a rather curious outcome given that the LCP was primarily a system of documentation, a tool with no intrinsic therapeutic properties. The Neuberger inquiry was the result of persistent and repeated reports of poor-quality end-of-life care associated with the use of the LCP. There were indeed problems with the LCP regarding the process of diagnosing dying and its approach to supportive care, particularly artificial nutrition and hydration. Some of the problems were the product of personal or professional ideology influencing goals of care rather than patient-centred considerations. These problems were not insurmountable, however, and were being addressed by the organisation responsible for the LCP. With the removal of the LCP, we are left with no bench mark for end-of-life care, only aspirational goals for individualised care plans. It seems unlikely that practitioners who could not provide appropriate care with the LCP will do so without it. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. SYNTHESIS AND CHARACTERIZATION OF TRIAZOLE CONTAINING LIQUID CRYSTALLINE POLYMERS THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Devamani; Srividhya; Sundaram; Manjunathan; Sivashankaran; Nithyanandan; Subramanan; Balamurugan; Sengodan; Senthil

    2009-01-01

    Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups.The structure of the polymer was confirmed by spectral techniques.GPC analysis reveals that the polymers have moderate molecular weight with narrow distributio...

  6. Three-dimensional RF SoP technologies: LTCC versus LCP

    KAUST Repository

    Arabi, Eyad A.

    2014-12-18

    The system on package (SoP) is an emerging platform, introduced to provide enhanced functionality, and immense miniaturization through vertically integrated passive components in a multilayer process. This way the package is not a mere holder or cover but is a functional part of the system. The leading multilayer packaging technologies for SoP designs: low temperature co-fired ceramic (LTCC) and liquid crystal polymer (LCP) are compared in this work for the first time. Passive components and filters have been implemented in both technologies to show the advantages of the three-dimensional nature of these technologies. The comparison results show that parallel plate capacitors implemented in the ultra-thin LCP provides the highest capacitance density. For spiral inductors, conversely, LTCC inductors have the highest inductances while LCP inductors offer the highest self-resonant frequencies and the highest quality factors (Q). In a circuit level, simulated and measured results of a bandpass filter at 1.5 GHz show that both LCP and LTCC can provide similar performances with an incredible size reduction for the case of ultra-thin LCP. Also, the thin LCP filter exhibits a large degree of mechanical flexibility which makes this technology suitable for future flexible modules.

  7. Liquid-crystalline polymer holograms for high-density optical storage and photomechanical analysis

    Science.gov (United States)

    Shishido, A.; Akamatsu, N.

    2012-10-01

    We report linear and crosslinked azobenzene containing liquid-crystalline polymers which can be applied to high-density optical storage and photomechanical analysis. We introduced a molecular design concept of multicomponent systems composed of photoresponse, refactive-index change amplification, and transparency units. Taking advantage of characteristics of liquid crystals (optical anisotropy and cooperative motion), polarization holograms were recorded, which enabled us higher-density holographic storage. On the other hand, crosslinked liquid-crystalline azobenzene polymer films were fabricated to investigate the photomechanical behavior. We have found that a large change in Young's modulus is induced by several mol%-cis form production. Furthermore, a unique bending behavior, which cannot be explained by the conventional bending mechanism, was observed in the crosslinked liquid-crystalline polymer films with azobenzene in the side chain.

  8. Phase diagrams and kinetics of solid-liquid phase transitions in crystalline polymer blends

    Science.gov (United States)

    Matkar, Rushikesh A.

    A free energy functional has been formulated based on an order parameter approach to describe the competition between liquid-liquid phase separation and solid-liquid phase separation. In the free energy description, the assumption of complete solvent rejection from the crystalline phase that is inherent in the Flory diluent theory was removed as solvent has been found to reside in the crystalline phase in the form of intercalates. Using this approach, we have calculated various phase diagrams in binary blends of crystalline and amorphous polymers that show upper or lower critical solution temperature. Also, the discrepancy in the chi values obtained from different experimental methods reported in the literature for the polymer blend of poly(vinylidenefluoride) and poly(methylmethacrylate) has been discussed in the context of the present model. Experimental phase diagram for the polymer blend of poly(caprolactone) and polystyrene has also been calculated. Of particular importance is that the crystalline phase concentration as a function of temperature has been calculated using free energy minimization methods instead of assuming it to be pure. In the limit of complete immiscibility of the solvent in the crystalline phase, the Flory diluent theory is recovered. The model is extended to binary crystalline blends and the formation of eutectic, peritectic and azeotrope phase diagrams has been explained on the basis of departure from ideal solid solution behavior. Experimental eutectic phase diagram from literature of a binary blend of crystalline polymer poly(caprolactone) and trioxane were recalculated using the aforementioned approach. Furthermore, simulations on the spatio temporal dynamics of crystallization in blends of crystalline and amorphous polymers were carried out using the Ginzburg-Landau approach. These simulations have provided insight into the distribution of the amorphous polymer in the blends during the crystallization process. The simulated results

  9. Cross-Linked Liquid Crystalline Systems From Rigid Polymer Networks to Elastomers

    CERN Document Server

    Broer, Dirk

    2011-01-01

    With rapidly expanding interest in liquid crystalline polymers and elastomers among the liquid crystal community, researchers are currently exploring the wide range of possible application areas for these unique materials, including optical elements on displays, tunable lasers, strain gauges, micro-structures, and artificial muscles. Written by respected scientists from academia and industry around the world, who are not only active in the field but also well-known in more traditional areas of research, "Cross-Linked Liquid Crystalline Systems: From Rigid Polymer Networks to Elastomers&qu

  10. Periodic orientational motions of rigid liquid-crystalline polymers in shear flow

    NARCIS (Netherlands)

    Tao, Y.G.; den Otter, Wouter K.; Briels, Willem J.

    2006-01-01

    The collective periodic motions of liquid-crystalline polymers in a nematic phase in shear flow have, for the first time, been simulated at the particle level by Brownian dynamics simulations. A wide range of parameter space has been scanned by varying the aspect ratio L/D between 10 and 60 at three

  11. Layer Formation and Annihilation in an Immiscible Polymer Blend under Electric and Shear Flow Fields

    OpenAIRE

    Na, Yang-Ho; Yoshino, Ayaka; Tominaga, Shinsuke; Orihara, Hiroshi; Ujie, Seiji; Nagaya, Tomoyuki

    2006-01-01

    Simultaneous observation of morphological change and measurement of shear stress in an immiscible polymer blend of a liquid crystalline polymer (LCP) and a methyl phenyl silicone oil (MPS) were carried out in electric and shear flow fields by using a system combining a rheometer and a confocal scanning laser microscope (CSLM). Under shear flow and no electric field a thin MPS layer with low viscosity was formed between two parallel plates of the rheometer, which reduced the app...

  12. Microstructure of Amorphous and Semi-Crystalline Polymers.

    Science.gov (United States)

    1981-06-07

    were bisphenol-A polycarbonate (P(’), amorphous poly(ethylene terephthalate ) ( PET ). poly(vinyl chloride) (PVC). and polystyrene (PS). The samples were...polystyrene, polyethylene terephthalate and polyvinyl chloride. Appropriately thin samples of these polymers were cast from solutions using the same... polycarbonate , poly(methyl meth- acrylate), poly(ethylene terephthalate ), poly(vinyl chloride) and polystyrene is inconsistent, both in the form and

  13. SYNTHESIS AND CHARACTERIZATION OF β-DIKETONE BASED SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANES

    Institute of Scientific and Technical Information of China (English)

    WU Fuzhou; ZHANG Rongben; JIANG Yingyan

    1990-01-01

    A new type of β-diketone based side chain liquid crystalline polysiloxanes (DKLCP) with different length of flexible spacers and end groups have been synthesized by hydrosilation reaction. This is liquid crystal polymers (LCP) using coordinating β-diketone ligand as mesogens. The phase behaviour of DKLCP polymers was studied by differential scanning calorimetry and polarizing microscopy.X-ray diffraction investigations demonstrated that the polysiloxanes with sufficiently long flexible spacers were smectic liquid crystal polymers, while those with much shorter spacers were nematic ones.

  14. Influence of annealing and blending of photoactive polymers on their crystalline structure.

    Science.gov (United States)

    Ruderer, Matthias A; Prams, Stefan M; Rawolle, Monika; Zhong, Qi; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter

    2010-12-02

    Thin photoactive polymer films of poly(3-octylthiophene-2,5-diyl) (P3OT) and poly(2,5-di(hexyloxy)cyanoterephthalylidene) (CN-PPV) are investigated. With X-ray reflectivity measurements, a linear concentration-thickness dependence is found for both polymers and the molecular weight of CN-PPV is determined from this concentration-thickness dependence. Based on the molecular weights, the critical blending ratio is determined. Grazing incidence wide-angle X-ray scattering (GIWAXS) is used to probe the crystallinity of thin films and to determine characteristic length scales of the crystalline structure. Moreover, the orientation of the crystalline parts regarding the substrate of both the homopolymer and the blended films is probed with GIWAXS. Temperature annealing is found to improve the crystallization for both homopolymers. In addition, reorientation of the predominant crystalline structures takes place. Blending both polymers reduces or even suppresses the crystallization during spin coating as well as temperature annealing. Absorption measurements complement the structural investigations.

  15. Unification of binary and LCP fission processes

    Science.gov (United States)

    Asghar, M.; Bouzid, B.; Medkour, G.; Djebara, M.

    1996-11-01

    This paper discusses the ambiguities of the parameters of the models used to calculate the yields of binary and light-charged-particle-accompanied (LCP) ternary fission processes. A model based on the adiabatic perturbation theory is set up. It removes these ambiguities and helps to treat the two processes in a unified way.

  16. Graphic Interface for LCP2 Optimization Program

    DEFF Research Database (Denmark)

    Nicolae, Taropa Laurentiu; Gaunholt, Hans

    1998-01-01

    This report provides information about the software interface that is programmed for the Optimization Program LCP2. The first part is about the general description of the program followed by a guide for using the interface. The last chapters contain a discussion about problems or futute extension...

  17. Anchoring Strength of Thin Aligned-Polymer Films Formed by Liquid Crystalline Monomer

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Ikehata, Seiichiro; Sato, Fumio

    2003-04-01

    We have evaluated the polar anchoring strength of a thin molecule-aligned polymer film formed by a liquid crystalline monomer. The polymer film was obtained by photopolymerization of the monomer oriented by a rubbed polyimide alignment layer in a chamber filled with N2 gas. We fabricated a nematic liquid crystal cell using the thin aligned-polymer films as alignment layers, and then evaluated the anchoring strength of the polymer by measuring the optical retardation curve of the cell driven by voltages. The experimental result showed that the anchoring strength was one order of magnitude lower than that of a conventional rubbed polyimide alignment layer, and decreased with increasing the cure temperature of the monomer film.

  18. Structural and Optical Properties of Single Crystalline Bismuth Nanoparticles in Polymer

    Science.gov (United States)

    Kabir, Lutful; Mandal, Swapan K.

    We report here the structural and optical properties of Bi nanoparticles in polymer (polypyrrole) matrix. The nanoparticles are synthesized following a wet chemical route. The X-ray diffraction data clearly shows the growth of single crystalline Bi nanoparticles within the host polymer. The microstructure of the Bi nanoparticles obtained by transmission electron microscopy (TEM) reveals clearly the formation of spherical shaped nanoparticles of average size˜27 nm with a narrow size distribution. The optical absorption spectrum exhibits a distinct peak at 278 nm which is attributed to the surface plasmon band of Bi nanoparticles. The absorption spectrum is found to be described well following Mie theory.

  19. Optical and Physical Applications of Photocontrollable Materials: Azobenzene-Containing and Liquid Crystalline Polymers

    Directory of Open Access Journals (Sweden)

    Takashi Fukuda

    2012-01-01

    Full Text Available Photocontrol of molecular alignment is an exceptionally-intelligent and useful strategy. It enables us to control optical coefficients, peripheral molecular alignments, surface relief structure, and actuation of substances by means of photoirradiation. Azobenzene-containing polymers and functionalized liquid crystalline polymers are well-known photocontrollable materials. In this paper, we introduce recent applications of these materials in the fields of mechanics, self-organized structuring, mass transport, optics, and photonics. The concepts in each application are explained based on the mechanisms of photocontrol. The interesting natures of the photocontrollable materials and the conceptual applications will stimulate novel ideas for future research and development in this field.

  20. Synthesis and characterization of organic-inorganic hybrids formed between conducting polymers and crystalline antimonic acid

    Directory of Open Access Journals (Sweden)

    Beleze Fábio A.

    2001-01-01

    Full Text Available In this paper we report the synthesis and characterization of novel organic-inorganic hybrid materials between the crystalline antimonic acid (CAA and two conductive polymers: polypyrrole and polyaniline. The hybrids were obtained by in situ oxidative polymerization of monomers by the Sb(V present in the pyrochlore-like CAA structure. The materials were characterized by infrared and Raman spectroscopy, X-ray diffraction, cyclic voltammetry, CHN elemental analysis and electronic paramagnetic resonance spectroscopy. The results showed that both polymers were formed in their oxidized form, with the CAA structure acting as a counter anion.

  1. Self-assembly of azobenzene based side-chain liquid crystalline polymer and -alkyloxybenzoic acids

    Indian Academy of Sciences (India)

    Kumarasamy Gayathri; Subramanian Balamurugan; Palaninathan Kannan

    2011-05-01

    Liquid crystalline pendant polymeric complexes have been obtained by supramolecular assembly of two mesogenic components namely, poly[4-(10-acryloyloxydecyloxy)-4'- phenylazobenzonitrile] (P10) and 4-alkyloxybenzoic acids (A7-A12). Hydrogen bond formed between carboxylic acid and cyano moiety served as molecular bridge. The polymeric complexes acquitted as undivided liquid crystalline properties exhibited stable and enantiotropic mesophases. The precursor, monomer and polymer were analysed by 1H-NMR and 13C-NMR spectroscopy. The hydrogen bonding interaction in polymer complexes (P10-A7 to P10-A12) was investigated by FT-IR spectroscopy. The thermal behaviours and textural analysis were studied by differential scanning calorimetry and polarized optical microscopy respectively.

  2. Co-rotational Oldroyd Fluid B Model for Spinning Flow of Liquid Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    付强

    2003-01-01

    The relationship between the extensional viscosity and material parameters was studied through the analytical formulas of stress and extensional viscosity. The differential equations were solved to obtain the relationship between extensional viscosity and strain rates. The results obtained qualitatively agree with the experimental results. The study makes it practicable to simulate the rheologic behaviors of spinning flow of liquid crystalline polymer using co-rotational Oldroyd fluid B model.

  3. Studies on the Synthesis,Characterization and Properties of the Reactive Thermotropic Liquid Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Introduction Four species of reactive thermotropic liquid crystalline polymer (LCMC) with different relative molecular weight were synthesized in this work (see scheme 1, n=2, 6, 10, ∞.n means number of repeat structure unit). Their structure, morphology and properties were investigated systemically by differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Wide-angle X-ray diffraction (WAXD), polarizing opticalmicroscopy (POM) and ubb...

  4. Hydrodynamic theories for mixtures of polymers and rodlike liquid crystalline polymers.

    Science.gov (United States)

    Forest, M Gregory; Wang, Qi

    2005-10-01

    We develop a hydrodynamic theory for flows of incompressible blends of flexible polymers and rodlike nematic polymers (RNPs) or rodlike nematic liquid crystal polymers (RNLCPs) extending the thermodynamical theory of Muratov and E [J. Chem. Phys. 116, 4723 (2002)] for phase separation kinetics of the blend. We model the flexible polymer molecules in the polymer matrix as Rouse chains and assume the translational diffusion of the molecules is predominantly through the volume fraction of the flexible polymer and the molecules of rodlike nematic liquid crystal polymers. We then (i) derive the translational flux for the rodlike nematic liquid crystal polymers to ensure the incompressibility constraint; (ii) derive the elastic stress tensor, accounting for the contribution from both the rodlike nematic polymer and the flexible polymer matrix, as well as the extra elastic body force due to the nonlocal intermolecular potential for long range molecular interaction; (iii) show that the theory obeys positive entropy production and thereby satisfies the second law of thermodynamics. By applying the gradient expansion technique on the number density function of RNLCPs, we present an approximate, weakly nonlocal theory in differential form in which the intermolecular potential is given by gradients of the number density function of the RNLCP and the volume fraction of the flexible polymer. In the approximate theory, the elastic stress is augmented by an extra stress tensor due to the spatial convection of the macroscopic material point and long range interaction, whose divergence yields the analogous extra elastic body force with respect to the nonlocal intermolecular potential. Finally, we compare the model in steady simple shear with the Doi theory for bulk monodomains of rodlike nematic polymers.

  5. Shape-memory behavior of cross-linked semi-crystalline polymers and their blends

    Directory of Open Access Journals (Sweden)

    I. Kolesov

    2015-03-01

    Full Text Available The present study deals with thermally induced one-way and invertible two-way shape-memory effect (SME in covalent networks on the basis of crystallizable (copolymers and their blends and is an attempt to generalize the results of own investigation received by the authors in the last ten years. The main focus of work clearly lies on research of covalently crosslinked binary and ternary blends having two and three crystalline phases with different thermal stability, respectively. The existence of two or three crystalline phases possessing different melting and crystallization temperatures in heterogeneous polymer networks can lead to triple-shape or even quadruple-shape behavior of such networks. However, the performed investigations point to crucial effect of phase morphology of crosslinked polymer blends on multiplicity of their shapememory behavior beside the influence of blend content, crystallinity and cross-link density of blend phases as well as of processing conditions. For instance, triple-shape memory behavior in binary blends can be realized only if the continuous phase has a lower melting temperature than the dispersed phase. Cross-linked polymer blends are a facile alternative to expensive and complex synthesis of interpenetrating or block-copolymer networks used for shape memory polymers. In addition to findings of experimental investigation of SME in crystallizable covalent polymer networks, the results of modeling their shape-memory behavior on the basis of self-developed physically reasonable model have been briefly described and discussed. Thereby, good accordance between results of theory and experiment was achieved with physically justified fitting parameters.

  6. A new series of two-ring-based side chain liquid crystalline polymers: synthesis and mesophase characterization

    CSIR Research Space (South Africa)

    Reddy, GSM

    2013-05-01

    Full Text Available A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl rings...

  7. SYNTHESIS AND PROPERTIES OF NEW SIDE-CHAIN LIQUID CRYSTALLINE POLYMER WITH LATERALLY ATTACHED MESOGENS BY ESTER GROUP

    Institute of Scientific and Technical Information of China (English)

    Qi-ding Mi; Qi-feng Zhou

    1999-01-01

    New liquid crystalline monomer, 2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully synthesized. Polyacrylate with laterally attached mesogens via ester linkage was also derived.This polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematic phase with respect to the crystalline state. However, its liquid crystallinity is very low as compared to that of poly { 2,5-bis[(4'-methoxyphenoxy)carbonyl] -styrene }.

  8. The ESEM used to image crystalline structures of polymers and to image ink on paper.

    Science.gov (United States)

    Rask, J H; Flood, J E; Borchardt, J K; York, G A

    1993-08-01

    This article describes two cases in which the advantages of the ESEM have been exploited in unanticipated ways. First, we have found that etching occurs as the electron beam scans the surface of uncoated polymers in the ESEM. The surface topography caused by this etching, as seen in ESEM images, reflects the morphology of crystalline structures in the polymers. This technique has been valuable in the study of such textures in polymers. The second application is related to our use of the ESEM in support of research on the deinking of paper. In this effort we have learned that an unconventional contrast mechanism can be used during ESEM imaging to distinguish between inked and non-inked areas of newsprint. Under usual operating conditions, ESEM imaging does not distinguish between inked and non-inked areas. However, at relatively low sample chamber pressures the non-inked areas appear brighter than inked areas in ESEM images.

  9. MORPHOLOGICAL AND KINETIC STUDIES OF PHASE TRANSITIONS OF A SIDE-CHAIN LIQUID CRYSTALLINE POLYMER

    Institute of Scientific and Technical Information of China (English)

    Chi-bing Tan; Shu-fan Zhang; Mao Xu

    1999-01-01

    The morphological changes of a side-chain liquid-crystalline polymethacrylate during isotropization and liquid-crystallization transitions were studied by means of polarizing microscopy. These transitions were found to be composed of the initiation of a new phase at local places of the old phase matrix and the growth of the new phase domains. The kinetics of the liquid-crystallization of the polymer from an isotropic melt to a smectic mesophase was also investigated. The isothermal process of the transition can be described by the Avrami equation. The values of the Avrami exponent were found to be around 2.6. which is lower than the value usually obtained for crystallization transition of polymers, but larger than that reported for liquid-crystallization transition of main-chain polymers. These results may indicate the difference in growth geometry of new phase during transition between crystallization and liquid-crystallization in general and between liquid-crystallization of main-chain and side-chain polymers. It was found that the liquidcrystallization of the used side-chain polymethacrylate may occur at small undercoolings with high transformation rate similar to that of main-chain polymers and small-molecule liquid crystals, while the crystallization of polymers can only proceed at large undercoolings. These phenomena can be explained by the idea that the surface free energy of nucleus during liquid-crystallization transition is less than that for crystallization, and evidence was obtained from analysis of the temperature dependence of the transformation rate.

  10. Hydrophilic-hydrophobic polymer blend for modulation of crystalline changes and molecular interactions in solid dispersion.

    Science.gov (United States)

    Van Ngo, Hai; Nguyen, Phuc Kien; Van Vo, Toi; Duan, Wei; Tran, Van-Thanh; Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh

    2016-11-20

    This research study aimed to develop a new strategy for using a polymer blend in solid dispersion (SD) for dissolution enhancement of poorly water-soluble drugs. SDs with different blends of hydrophilic-hydrophobic polymers (zein/hydroxypropyl methylcellulose - zein/HPMC) were prepared using spray drying to modulate the drug crystal and polymer-drug interactions in SDs. Physicochemical characterizations, including power X-ray diffraction and Fourier transform infrared spectroscopy, were performed to elucidate the roles of the blends in SDs. Although hydrophobic polymers played a key role in changing the model drug from a crystal to an amorphous state, the dissolution rate was limited due to the wetting property. Fortunately, the hydrophilic-hydrophobic blend not only reduced the drug crystallinity but also resulted in a hydrogen bonding interaction between the drugs and the polymer for a dissolution rate improvement. This work may contribute to a new generation of solid dispersion using a blend of hydrophilic-hydrophobic polymers for an effective dissolution enhancement of poorly water-soluble drugs.

  11. PERITROCHANTERIC FRACTURES - SURGICAL MANAGEMENT BY PF - LCP

    Directory of Open Access Journals (Sweden)

    Kiran

    2014-07-01

    Full Text Available : Background and objectives: - Due to increasing life span and sedentary habits of elderly people fractures around hip are common. Among these, peritrochanteric fractures are commonest and they need immediate and stable reconstruction to mobilize the affected patients. METHODS: We studied 20 cases of peritrochanteric fractures treated by PF-LCP at KR hospital, MMCRI from Sep 2013- May 2014. They included 14 male and 6 female patients of age group from 28 yrs. to 75 yrs. the cause of injury was trivial in 80%, RTA in 20% of cases. Follow up was done for 6-8 months and assessed using Boyd and Griffin’s classification and Harris hip score. RESULTS: Among the selected cases we evaluated both clinically and radiologically at the intervals of 6th, 12th, and 6 months we found that the final outcome was better than the cases treated with other type of implants and treated conservatively. The union rate was 40% (8/20 and 85% (17/20 at the 12th week and 6 months follow up respectively. We had 1 case of complication as cut-out of screws from proximal fragment. CONCLUSION: The peritrochanteric fractures when treated with PF-LCP resulted in stable reconstruction of fracture and maintenance of anatomical reduction and bio-mechanical axis. Because of its strong angular fixation by the top three screws PF-LCP is advantageous in all types of bone density.

  12. A CONSTRAINED OPTIMIZATION APPROACH FOR LCP

    Institute of Scientific and Technical Information of China (English)

    Ju-liang Zhang; Jian Chen; Xin-jian Zhuo

    2004-01-01

    In this paper, LCP is converted to an equivalent nonsmooth nonlinear equation system H(x, y) = 0 by using the famous NCP function-Fischer-Burmeister function. Note that some equations in H(x, y) = 0 are nonsmooth and nonlinear hence difficult to solve while the others are linear hence easy to solve. Then we further convert the nonlinear equation system H(x, y) = 0 to an optimization problem with linear equality constraints. After that we study the conditions under which the K T points of the optimization problem are the solutions of the original LCP and propose a method to solve the optimization problem.In this algorithm, the search direction is obtained by solving a strict convex programming at each iterative point. However, our algorithm is essentially different from traditional SQP method. The global convergence of the method is proved under mild conditions. In addition, we can prove that the algorithm is convergent superlinearly under the conditions:M is P0 matrix and the limit point is a strict complementarity solution of LCP. Preliminary numerical experiments are reported with this method.

  13. Molecular orientation of individual LCP particles in injection-moulded PPS/LCP blends

    Directory of Open Access Journals (Sweden)

    Kestenbach H.-J.

    2003-01-01

    Full Text Available Polarized light microscopy was used to investigate the presence of preferred molecular orientation in the LCP phase of PPS/LCP blends after injection moulding. Normal birefringence effects appeared to be complicated by artifacts due to sample preparation and by the complex nature of polarized light transmission through a multicomponent sample. It was found, however, that, during low-temperature cutting of optically transparent thin sections on a standard microtome, individual LCP particles could be separated from the PPS matrix, and their birefringence analyzed separately. Preferred orientation was detected only in LCP fibrils which dominated in skin regions, but not in droplet-shaped particles which had formed in core regions. Quantitative measurements indicated that the molecular orientation of the fibrils increased linearly with their length-to-diameter aspect ratios which ranged from 15 to 50. Even for the highest aspect ratios, however, the degree of orientation was always less than that which could easily be introduced into pure LCP thin-film samples by manual shearing.

  14. NATO Advanced Research Workshop on Computational Methods for Polymers and Liquid Crystalline Polymers

    CERN Document Server

    Pasini, Paolo; Žumer, Slobodan; Computer Simulations of Liquid Crystals and Polymers

    2005-01-01

    Liquid crystals, polymers and polymer liquid crystals are soft condensed matter systems of major technological and scientific interest. An understanding of the macroscopic properties of these complex systems and of their many and interesting peculiarities at the molecular level can nowadays only be attained using computer simulations and statistical mechanical theories. Both in the Liquid Crystal and Polymer fields a considerable amount of simulation work has been done in the last few years with various classes of models at different special resolutions, ranging from atomistic to molecular and coarse-grained lattice models. Each of the two fields has developed its own set of tools and specialized procedures and the book aims to provide a state of the art review of the computer simulation studies of polymers and liquid crystals. This is of great importance in view of a potential cross-fertilization between these connected areas which is particularly apparent for a number of experimental systems like, e.g. poly...

  15. Comparison of filters: Inkjet printed on PEN substrate versus a laser-etched on LCP substrate

    KAUST Repository

    Arabi, Eyad A.

    2014-10-01

    In this paper, microstrip-based bandpass filters on polyethylene naphthalate (PEN) and liquid crystal polymers (LCP) are presented to investigate the performance of filters on ultra-thin substrates. PEN (with a thickness of 120 μm) has been characterized and used for a filter for the first time. In addition to being low cost and transparent, it demonstrates comparable RF performance to LCP. The conductor losses are compared by fabricating filters with inkjet printed lines as well as laser etched copper clad LCP sheets. With 5 layers of inkjet printing, and a curing temperature below 200°C, a final silver thickness of 2 μm and conductivity of 9.6 × 106 S/m are achieved. The designs are investigated at two frequencies, 24 GHz as well as 5 GHz to assess their performance at high and low frequencies respectively. The 24 GHz inkjet printed filter shows an insertion loss of 2 dB, while the 5 GHz design gives an insertion loss of 8 dB. We find that thin substrates have a strong effect on the insertion loss of filters especially as the frequency is reduced. The same design, realized on LCP (thickness of 100 μm) through laser etching, demonstrates a very similar performance, thus verifying this finding. © 2014 European Microwave Association.

  16. Tunable Photocontrolled Motions Using Stored Strain Energy in Malleable Azobenzene Liquid Crystalline Polymer Actuators.

    Science.gov (United States)

    Lu, Xili; Guo, Shengwei; Tong, Xia; Xia, Hesheng; Zhao, Yue

    2017-07-01

    A new strategy for enhancing the photoinduced mechanical force is demonstrated using a reprocessable azobenzene-containing liquid crystalline network (LCN). The basic idea is to store mechanical strain energy in the polymer beforehand so that UV light can then be used to generate a mechanical force not only from the direct light to mechanical energy conversion upon the trans-cis photoisomerization of azobenzene mesogens but also from the light-triggered release of the prestored strain energy. It is shown that the two mechanisms can add up to result in unprecedented photoindued mechanical force. Together with the malleability of the polymer stemming from the use of dynamic covalent bonds for chain crosslinking, large-size polymer photoactuators in the form of wheels or spring-like "motors" can be constructed, and, by adjusting the amount of prestored strain energy in the polymer, a variety of robust, light-driven motions with tunable rolling or moving direction and speed can be achieved. The approach of prestoring a controllable amount of strain energy to obtain a strong and tunable photoinduced mechanical force in azobenzene LCN can be further explored for applications of light-driven polymer actuators. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Engineering the Crystalline Morphology of Polymer Thin Films via Physical Vapor Deposition

    Science.gov (United States)

    Jeong, Hyuncheol; Arnold, Craig; Priestley, Rodney

    Thin-film growth via physical vapor deposition (PVD) has been successfully exploited for the delicate control of film structure for molecular and atomic systems. The application of such a high-energetic process to polymeric film growth has been challenged by chemical degradation. However, recent development of Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique opened up a way to deposit a variety of macromolecules in a PVD manner. Here, employing MAPLE technique to the growth of semicrystalline polymer thin films, we show the engineering of crystalline film morphology can be achieved via manipulation of substrate temperature. This is accomplished by exploiting temperature effect on crystallization kinetics of polymers. During the slow film growth crystallization can either be permitted or suppressed, and crystal thickness can be tuned via temperature modulation. In addition, we report that the crystallinity of polymer thin films may be significantly altered with deposition temperature in MAPLE processing. We expect that this ability to manipulate crystallization kinetics during polymeric film growth will open the possibility to engineer structure in thin film polymeric-based devices in ways that are difficult by other means.

  18. Demixing by a Nematic Mean Field: Coarse-Grained Simulations of Liquid Crystalline Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Hernández, Abelardo; Hur, Su-Mi; Armas-Pérez, Julio; Cruz, Monica; de Pablo, Juan

    2017-03-01

    Liquid crystalline polymers exhibit a particular richness of behaviors that stems from their rigidity and their macromolecular nature. On the one hand, the orientational interaction between liquid-crystalline motifs promotes their alignment, thereby leading to the emergence of nematic phases. On the other hand, the large number of configurations associated with polymer chains favors formation of isotropic phases, with chain stiffness becoming the factor that tips the balance. In this work, a soft coarse-grained model is introduced to explore the interplay of chain stiffness, molecular weight and orientational coupling, and their role on the isotropic-nematic transition in homopolymer melts. We also study the structure of polymer mixtures composed of stiff and flexible polymeric molecules. We consider the effects of blend composition, persistence length, molecular weight and orientational coupling strength on the melt structure at the nano-and mesoscopic levels. Conditions are found where the systems separate into two phases, one isotropic and the other nematic. We confirm the existence of non-equilibrium states that exhibit sought-after percolating nematic domains, which are of interest for applications in organic photovoltaic and electronic devices.

  19. The effect of calcining temperature on the properties of 0-3 piezoelectric composites of PZT and a liquid crystalline thermosetting polymer

    NARCIS (Netherlands)

    Ende, D.A. van den; Groen, W.A.; Zwaag, S. van der

    2011-01-01

    We report on the optimisation of a recently developed high performance 0-3 piezoelectric composite comprising of the piezoelectric Lead Zirconate Titanate (PZT) powder and a liquid crystalline thermosetting matrix polymer (LCT). The matrix polymer is a liquid crystalline polymer comprising of an HBA

  20. A simple route to enhance the interface between graphite oxide nanoplatelets and a semi-crystalline polymer for stress transfer

    Science.gov (United States)

    Cai, Dongyu; Song, Mo

    2009-08-01

    This report shows that thermal treatment is a simple and effective approach to create a polymer crystalline layer on the surface of graphite oxide nanoplatelets (GONPs) in polycaprolactone (PCL) melts. It was found that the crystallization temperature of the PCL increased significantly by nearly 9 °C with the incorporation of 2 wt% GONPs. As the composite melts isothermally crystallized at the temperature that was 14 °C higher than the crystallization temperature, the polymer crystalline layer was optimized on the surface of the GONPs. At 2 wt% GONPs, the Young's modulus of the composite was nearly 1.5 times greater than for the pure PCL. In comparison with untreated composites, the improvement in the Young's modulus of treated composites nearly doubled. It confirmed that a non-covalent interface for stress transfer can be enhanced by the formation of the polymer crystalline layer bridging the GONPs and the polymer matrix.

  1. Selecting polymers for two-phase partitioning bioreactors (TPPBs): Consideration of thermodynamic affinity, crystallinity, and glass transition temperature.

    Science.gov (United States)

    Bacon, Stuart L; Peterson, Eric C; Daugulis, Andrew J; Parent, J Scott

    2015-01-01

    Two-phase partitioning bioreactor technology involves the use of a secondary immiscible phase to lower the concentration of cytotoxic solutes in the fermentation broth to subinhibitory levels. Although polymeric absorbents have attracted recent interest due to their low cost and biocompatibility, material selection requires the consideration of properties beyond those of small molecule absorbents (i.e., immiscible organic solvents). These include a polymer's (1) thermodynamic affinity for the target compound, (2) degree of crystallinity (wc ), and (3) glass transition temperature (Tg ). We have examined the capability of three thermodynamic models to predict the partition coefficient (PC) for n-butyric acid, a fermentation product, in 15 polymers. Whereas PC predictions for amorphous materials had an average absolute deviation (AAD) of ≥16%, predictions for semicrystalline polymers were less accurate (AAD ≥ 30%). Prediction errors were associated with uncertainties in determining the degree of crystallinity within a polymer and the effect of absorbed water on n-butyric acid partitioning. Further complications were found to arise for semicrystalline polymers, wherein strongly interacting solutes increased the polymer's absorptive capacity by actually dissolving the crystalline fraction. Finally, we determined that diffusion limitations may occur for polymers operating near their Tg , and that the Tg can be reduced by plasticization by water and/or solute. This study has demonstrated the impact of basic material properties that affects the performance of polymers as sequestering phases in TPPBs, and reflects the additional complexity of polymers that must be taken into account in material selection.

  2. Temperature influence in crystallinity of polymer microspheres; Influencia da temperatura na cristalinidade de microesferas polimericas

    Energy Technology Data Exchange (ETDEWEB)

    Rezende, Cristiane de P.; Novack, Katia M., E-mail: knovack@iceb.ufop.br [Universidade Federal de Ouro Preto - UFOP, ICEB, DEQUI, Ouro Preto, MG (Brazil)

    2011-07-01

    Drug delivery technology is evolving through the creation of new techniques of drug delivery effectively. The new methods used in drugs administration are based in microencapsulation process. Microsphere encapsulation modifies drug delivery bringing benefits and efficiency. In this work has been evaluated the influence of temperature in microspheres preparation. Microspheres were obtained by PMMA-co-PEG (COP) copolymer with indomethacin inserted in polymer matrix. Samples were characterized by SEM, DSC and XRD. SEM micrographs confirmed the formation of different sizes of microspheres and it was verified that higher temperatures make more crystalline microspheres. (author)

  3. Cure Reaction Kinetics of Low Pressure Sheet Molding Compound System Thickened by Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    QIN Yan; LIU Haihua; HUANG Zhixiong; MEI Qilin

    2007-01-01

    Several kinetic models for unsaturated polyester cure reaction and some existing parameter estimation techniques of these models were introduced. Correlated kinetic parameters and kinetic equations of the autocatalytic empirical kinetic model of LPSMC system were determined by using isothermal DSC to scan the system which was thickened by crystalline polymer (PEG-MAH). Through using a serial curing degree of the system to validate the model, the experimental results were basically identical with the predictions of the autocatalytic empirical kinetic model. This model could provide a theoretical reference to the determination of molding techniques of low pressure SMC.

  4. Interferometric Sensor of Wavelength Detuning Using a Liquid Crystalline Polymer Waveplate

    Directory of Open Access Journals (Sweden)

    Paweł Wierzba

    2016-05-01

    Full Text Available Operation of a polarization interferometer for measurement of the wavelength changes of a tunable semiconductor laser was investigated. A λ/8 waveplate made from liquid crystalline polymer is placed in one of interferometers’ arms in order to generate two output signals in quadrature. Wavelength was measured with resolution of 2 pm in the wavelength range 628–635 nm. Drift of the interferometer, measured in the period of 500 s, was 8 nm, which corresponded to the change in the wavelength of 1.3 pm. If needed, wavelength-dependent Heydemann correction can be used to expand the range of operation of such interferometer.

  5. Thermo- and photo-driven soft actuators based on crosslinked liquid crystalline polymers

    Science.gov (United States)

    Gu, Wei; Wei, Jia; Yu, Yanlei

    2016-09-01

    Crosslinked liquid crystalline polymers (CLCPs) are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks. The anisotropic deformation of the CLCPs takes place when the mesogens experience order to disorder change in response to external stimuli; therefore, they can be utilized to fabricate smart actuators, which have potential applications in artificial muscles, micro-optomechanical systems, optics, and energy-harvesting fields. In this review the recent development of thermo- and photo-driven soft actuators based on the CLCPs are summarized. Project supported by the National Natural Science Foundation of China (Grant Nos. 21134003, 21273048, 51225304, and 51203023) and Shanghai Outstanding Academic Leader Program, China (Grant No. 15XD1500600).

  6. Improving the performance of polymer solar cells by adjusting the crystallinity and nanoscale phase separation

    Institute of Scientific and Technical Information of China (English)

    Chen Wei-Bing; Xu Zong-Xiang; Li Kai; Chui Stephen Sin-Yin; Roy V.A.L.; Lai Pui-To; Che Chi-Ming

    2012-01-01

    In this paper,we report a high-performance P3HT/PCBM bulk-heterojunction solar cell with a power conversion efficiency of 4.85% fabricated by adjusting the polymer crystallinity and nanoscale phase separation using an ultrasonic irradiation mixing approach for the polymer.The grazing incidence X-ray diffraction,UV/Vis spectroscopic,and atomic force microscopic measurement results for the P3HT/PCBM blend films reveal that the P3HT/PCBM film fabricated by ultrasonic irradiation mixing of the P3HT and PCBM solutions for 10 min has a higher degree of cryetallinity,a higher absorption efficiency,and better phase separation,which together account for the higher charge transport properties and photovoltaic cell performance.

  7. Determination of the solubility of crystalline low molar mass compounds in polymers by differential scanning calorimetry.

    Science.gov (United States)

    Rager, Timo

    2014-06-01

    A mathematical equation has been derived to calculate the liquidus for a binary system consisting of an amorphous polymer and a crystalline low molar mass compound. The experimental input to this equation is an interaction enthalpy, which is derived from the variation of the melting enthalpy with composition in differential scanning calorimetry (DSC) experiments. The predictive power of the equation has been tested with mixtures of acetylsalicylic acid, carbamazepine, or intraconazole with poly(ethylene glycol) as well as mixtures of carbamazepine with poly(acrylic acid), poly(hydroxystyrene), or poly(vinylpyrrolidone). It has been confirmed that the evaluation of the melting enthalpy in DSC is a suitable method to identify the preferred solute-polymer combinations for thermodynamically stable molecular dispersions. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  8. Optical Input/Electrical Output Memory Elements based on a Liquid Crystalline Azobenzene Polymer.

    Science.gov (United States)

    Mosciatti, Thomas; Bonacchi, Sara; Gobbi, Marco; Ferlauto, Laura; Liscio, Fabiola; Giorgini, Loris; Orgiu, Emanuele; Samorì, Paolo

    2016-03-01

    Responsive polymer materials can change their properties when subjected to external stimuli. In this work, thin films of thermotropic poly(metha)acrylate/azobenzene polymers are explored as active layer in light-programmable, electrically readable memories. The memory effect is based on the reversible modifications of the film morphology induced by the photoisomerization of azobenzene mesogenic groups. When the film is in the liquid crystalline phase, the trans → cis isomerization induces a major surface reorganization on the mesoscopic scale that is characterized by a reduction in the effective thickness of the film. The film conductivity is measured in vertical two-terminal devices in which the polymer is sandwiched between a Au contact and a liquid compliant E-GaIn drop. We demonstrate that the trans → cis isomerization is accompanied by a reversible 100-fold change in the film conductance. In this way, the device can be set in a high- or low-resistance state by light irradiation at different wavelengths. This result paves the way toward the potential use of poly(metha)acrylate/azobenzene polymer films as active layer for optical input/electrical output memory elements.

  9. Highly Crystalline and Low Bandgap Donor Polymers for Efficient Polymer Solar Cells

    Science.gov (United States)

    2012-01-01

    298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 539 www.advmat.de www.MaterialsViews.com C O M M U N IC A TIO N wileyonlinelibrary.com© 2012 WILEY-VCH...on the π–π packing of the main chains in EI-PFDTBT, as confirmed by X-ray diffraction ( XRD ) and UV/Vis absorption spectroscopic measurements...Figure 2a reproduces the XRD profile for a EI-PFDTBT powder. The strong diffraction peak at 21.3° indicates the 4.1 Å π-stacking spacing between polymer

  10. Effect of MWNTs and SiC-Coated MWNTs on Properties of PEEK/LCP Blend

    Directory of Open Access Journals (Sweden)

    Ganesh Chandra Nayak

    2009-01-01

    Full Text Available Multiwall carbon nanotubes (MWNTs were modified with polycarbosilane-derived silicon carbide (SiC to improve its dispersion in the polymer matrix. PEEK/LCP/MWNTs nanocomposites were prepared by melt blending. TEM images show the improved dispersion of SiC-coated MWNTs against agglomerated structure of pure MWNTs in the blend. FESEM images shows better fibrillation of LCP in presence of SiC-coated MWNTs. TGA reveals that nanocomposites with SiC-coated MWNTs shows higher thermal stability than MWNTs filled blend system. Based on enhanced dispersion, storage modulus, tensile modulus and tensile strength were increased drastically with the incorporation of SiC-coated MWNTs. Glass transition temperature of the nanocomposites shows significant improvement with the incorporation of MWNTs.

  11. Liquid crystalline phase transitions in virus and virus/polymer suspensions

    Science.gov (United States)

    Dogic, Zvonimir

    Using experimental, theoretical, and simulation methods, we investigate the relationship between the intermolecular interactions of rod-like colloids and the resulting liquid crystalline phase diagrams. As a model system of rod-like particles we use bacteriophage fd, which is a charge stabilized colloid. We are able to engineer complex attractive and repulsive intermolecular interactions by changing the ionic strengths of the suspensions, attaching covalently bound polymers and adding nonadsorbing polymers. Using standard molecular cloning techniques it is also shown that the aspect ratio of the rod-like particle can be manipulated. In the limit of high ionic strength the fd virus quantitatively agrees with the Onsager theory for the isotropic-nematic (I-N) phase transition in hard rods. The role of attractive interaction on the nature of the I-N phase transition is investigated. As the strength of the attraction is increased we observe isotropic-smectic (I-S) phase transitions. Using an optical microscope we follow the kinetics of the I-S phase transition and observe a wide range of novel structures of unexpected complexity. We also investigate the influence of adding hard spheres, or polymers on the nematic-smectic phase transition. We conclude that adding small spheres stabilizes the smectic phase and destabilizes the nematic phase.

  12. Photomobile polymer materials with crosslinked liquid-crystalline structures: molecular design, fabrication, and functions.

    Science.gov (United States)

    Ube, Toru; Ikeda, Tomiki

    2014-09-22

    Crosslinked liquid-crystalline polymer materials that macroscopically deform when irradiated with light have been extensively studied in the past decade because of their potential in various applications, such as microactuators and microfluidic devices. The basic motions of these materials are contraction-expansion and bending-unbending, which are observed mainly in polysiloxanes and polyacrylates that contain photochromic moieties. Other sophisticated motions such as twisting, oscillation, rotation, and translational motion have also been achieved. In recent years, efforts have been made to improve the photoresponsive and mechanical properties of this novel class of materials through the modification of molecular structures, development of new fabrication methods, and construction of composite structures. Herein, we review structures, functions, and working mechanisms of photomobile materials and recent advances in this field.

  13. Photo-Induced Bending Behavior of Post-Crosslinked Liquid Crystalline Polymer/Polyurethane Blend Films.

    Science.gov (United States)

    Pang, Xinlei; Xu, Bo; Qing, Xin; Wei, Jia; Yu, Yanlei

    2017-06-30

    Photoresponsive blend films with post-crosslinked liquid crystalline polymer (CLCP) as a photosensitive component and flexible polyurethane (PU) as the matrix are successfully fabricated. After being uniaxially stretched, even at low concentration, the azobenzene-containing CLCP effectively transfers its photoresponsiveness to the photoinert PU matrix, resulting in the fast photo-induced bending behavior of whole blend film thanks to the effective dispersion of CLCP. Specifically, the blend film shows photo-induced deformations upon exposure to unpolarized UV light at ambient temperature. The film unbends after thermal treatment, and the randomly orientated mesogens in the film can be realigned by the mechanical stretching, which endows the film with a reversible deformation behavior. The photosensitive blend film possesses favorable mechanical property and good processability at low cost, and it is a promising candidate for a new generation of actuators. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Kinetic theory for flows of nonhomogeneous rodlike liquid crystalline polymers with a nonlocal intermolecular potential.

    Science.gov (United States)

    Wang, Qi; E, Weinan; Liu, Chun; Zhang, Pingwen

    2002-05-01

    The Doi kinetic theory for flows of homogeneous, rodlike liquid crystalline polymers (LCPs) is extended to model flows of nonhomogeneous, rodlike LCPs through a nonlocal (long-range) intermolecular potential. The theory features (i) a nonlocal, anisotropic, effective intermolecular potential in an integral form that is consistent with the chemical potential, (ii) short-range elasticity as well as long-range isotropic and anisotropic elasticity, (iii) a closed-form stress expression accounting for the nonlocal molecular interaction, and (iv) an extra elastic body force exclusively associated with the integral form of the intermolecular potential. With the effective intermolecular potential, the theory is proven to be well posed in that it warrants a positive entropy production and thereby the second law of thermodynamics. Approximate theories are obtained by gradient expansions of the number density function in the free energy density.

  15. Macroscopic Ordering of CNTs in a Liquid Crystalline Polymer Nano-Composite by Shearing

    Science.gov (United States)

    Kalakonda, P.; Sarkar, S.; Iannacchione, G. S.; Gombos, E.; Hoonjan, G. S.; Georgiev, G.; Cebe, P.

    2012-02-01

    We present a series of complimentary experiments exploring the macroscopic alignment of carbon nanotubes (CNTs) in a liquid crystalline polymer (isotactic polypropylene - iPP) nano-composites as a function of temperature, shear, and CNT concentration. The phase behavior of iPP+CNT, studied by Modulated Differential Scanning Calorimetry, revealed the evolution of the α-monoclinic transition and its dynamics, which are dependent on CNT content and thermal treatment. These results indicate that the CNT nucleates crystal formation from the melt. Spectroscopic ellipsometry reveals a change in the optical constants that are connected to the ordering of CNTs when the iPP+CNT is sheared. This anisotropy is also exhibited in measurements of the electrical and thermal conductivities parallel and perpendicular to the shear direction. The amount of order induced into the dispersed CNTs is relatively low for these low concentration samples (< 5 wt%).

  16. EPR spectroscopy of protein microcrystals oriented in a liquid crystalline polymer medium

    Science.gov (United States)

    Caldeira, Jorge; Figueirinhas, João Luis; Santos, Celina; Godinho, Maria Helena

    2004-10-01

    Correlation of the g-tensor of a paramagnetic active center of a protein with its structure provides a unique experimental information on the electronic structure of the metal site. To address this problem, we made solid films containing metalloprotein ( Desulfovibrio gigas cytochrome c3) microcrystals. The microcrystals in a liquid crystalline polymer medium (water/hydroxypropylcellulose) were partially aligned by a shear flow. A strong orientation effect of the metalloprotein was observed by EPR spectroscopy and polarizing optical microscopy. The EPR spectra of partially oriented samples were simulated, allowing for molecular orientation distribution function determination. The observed effect results in enhanced sensitivity and resolution of the EPR spectra and provides a new approach towards the correlation of spectroscopic data, obtained by EPR or some other technique, with the three-dimensional structure of a protein or a model compound.

  17. Shape-Selectivity with Liquid Crystal and Side-Chain Liquid Crystalline Polymer SAW Sensor Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    FRYE-MASON,GREGORY CHARLES; OBORNY,MICHAEL C.; PUGH,COLEEN; RICCO,ANTONIO; THOMAS,ROSS C.; ZELLERS,EDWARD T.; ZHANG,GUO-ZHENG

    1999-09-23

    A liquid crystal (LC) and a side-chain liquid crystalline polymer (SCLCP) were tested as surface acoustic wave (SAW) vapor sensor coatings for discriminating between pairs of isomeric organic vapors. Both exhibit room temperature smectic mesophases. Temperature, electric-field, and pretreatment with self-assembled monolayers comprising either a methyl-terminated or carboxylic acid-terminated alkane thiol anchored to a gold layer in the delay path of the sensor were explored as means of affecting the alignment and selectivity of the LC and SCLCP films. Results for the LC were mixed, while those for the SCLCP showed a consistent preference for the more rod-like isomer of each isomer pair examined.

  18. Ab initio calculation of the crystalline structure and IR spectrum of polymers: nylon 6 polymorphs.

    Science.gov (United States)

    Quarti, Claudio; Milani, Alberto; Civalleri, Bartolomeo; Orlando, Roberto; Castiglioni, Chiara

    2012-07-19

    State-of-the-art computational methods in solid-state chemistry were applied to predict the structural and spectroscopic properties of the α and γ crystalline polymorphs of nylon 6. Density functional theory calculations augmented with an empirical dispersion correction (DFT-D) were used for the optimization of the two different crystal structures and of the isolated chains, characterized by a different regular conformation and described as one-dimensional infinite chains. The structural parameters of both crystalline polymorphs were correctly predicted, and new insight into the interplay of conformational effects, hydrogen bonding, and van der Waals interactions in affecting the properties of the crystal structures of polyamides was obtained. The calculated infrared spectra were compared to experimental data; based on computed vibrational eigenvectors, assignment of the infrared absorptions of the two nylon 6 polymorphs was carried out and critically analyzed in light of previous investigations. On the basis of a comparison of the computed and experimental IR spectra, a set of marker bands was identified and proposed as a tool for detecting and quantifying the presence of a given polymorph in a real sample: several marker bands employed in the past were confirmed, whereas some of the previous assignments are criticized. In addition, some new marker bands are proposed. The results obtained demonstrate that accurate computational techniques are now affordable for polymers characterization, opening the way to several applications of ab initio modeling to the study of many families of polymeric materials.

  19. Liquid crystalline polymers IX Main chain thermotropic poly (azomethine – ethers containing thiazole moiety linked with polymethylene spacers

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available A new homologous series of thermally stable thermotropic liquid crystalline poly(azomethine-ethers based on thiazole moiety were synthesized by solution polycondensation of 4,4`-diformyl-α,ω-diphenoxyalkanes, I–IV or 4,4`-diformyl-2,2`-dimethoxy-α,ω-diphenoxyalkanes V–VIII with the new bis(2-aminothiazole monomer X. A model compound XI was synthesized from X with benzaldehyde and characterized by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.43–1.34 dI/g. All the poly(azomethine-ethers were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by DSC and optical polarizing microscopy and demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by TGA and DSC measurements and correlated to their structural units. X-ray analysis showed that polymers having some degree of crystallinity in the region 2θ = 5–60°. In addition, the morphological properties of selected examples were tested by scanning electron microscopy.

  20. Free Surface Command Layer for Photoswitchable Out-of-Plane Alignment Control in Liquid Crystalline Polymer Films.

    Science.gov (United States)

    Nakai, Takashi; Tanaka, Daisuke; Hara, Mitsuo; Nagano, Shusaku; Seki, Takahiro

    2016-01-26

    To date, reversible alignment controls of liquid crystalline materials have widely been achieved by photoreactive layers on solid substrates. In contrast, this work demonstrates the reversible out-of-plane photocontrols of liquid crystalline polymer films by using a photoresponsive skin layer existing at the free surface. A polymethacrylate containing a cyanobiphenyl side-chain mesogen adopts the planar orientation. Upon blending a small amount of azobenzene-containing side-chain polymer followed by successive annealing, segregation of the azobenzene polymer at the free surface occurs and induces a planar to homeotropic orientation transition of cyanobiphenyl mesogens underneath. By irradiation with UV light, the mesogen orientation turns into the planar orientation. The orientation reverts to the homeotropic state upon visible light irradiation or thermally, and such cyclic processes can be repeated many times. On the basis of this principle, erasable optical patterning is performed by irradiating UV light through a photomask.

  1. Case report of LCP pediatric hip osteosynthesis of a proximal ...

    African Journals Online (AJOL)

    Case report of LCP pediatric hip osteosynthesis of a proximal femoral ... Pan African Medical Journal ... We present a case report demonstrating the experience of the department of pediatric orthopaedics of the University Orthopedic Hospital at ...

  2. A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics.

    Science.gov (United States)

    Kim, Bong-Gi; Jeong, Eun Jeong; Chung, Jong Won; Seo, Sungbaek; Koo, Bonwon; Kim, Jinsang

    2013-07-01

    Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur-fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.

  3. n-Type semiconducting naphthalene diimide-perylene diimide copolymers: controlling crystallinity, blend morphology, and compatibility toward high-performance all-polymer solar cells.

    Science.gov (United States)

    Hwang, Ye-Jin; Earmme, Taeshik; Courtright, Brett A E; Eberle, Frank N; Jenekhe, Samson A

    2015-04-08

    Knowledge of the critical factors that determine compatibility, blend morphology, and performance of bulk heterojunction (BHJ) solar cells composed of an electron-accepting polymer and an electron-donating polymer remains limited. To test the idea that bulk crystallinity is such a critical factor, we have designed a series of new semiconducting naphthalene diimide (NDI)-selenophene/perylene diimide (PDI)-selenophene random copolymers, xPDI (10PDI, 30PDI, 50PDI), whose crystallinity varies with composition, and investigated them as electron acceptors in BHJ solar cells. Pairing of the reference crystalline (crystalline domain size Lc = 10.22 nm) NDI-selenophene copolymer (PNDIS-HD) with crystalline (Lc = 9.15 nm) benzodithiophene-thieno[3,4-b]thiophene copolymer (PBDTTT-CT) donor yields incompatible blends, whose BHJ solar cells have a power conversion efficiency (PCE) of 1.4%. However, pairing of the new 30PDI with optimal crystallinity (Lc = 5.11 nm) as acceptor with the same PBDTTT-CT donor yields compatible blends and all-polymer solar cells with enhanced performance (PCE = 6.3%, Jsc = 18.6 mA/cm(2), external quantum efficiency = 91%). These photovoltaic parameters observed in 30PDI:PBDTTT-CT devices are the best so far for all-polymer solar cells, while the short-circuit current (Jsc) and external quantum efficiency are even higher than reported values for [70]-fullerene:PBDTTT-CT solar cells. The morphology and bulk carrier mobilities of the polymer/polymer blends varied substantially with crystallinity of the acceptor polymer component and thus with the NDI/PDI copolymer composition. These results demonstrate that the crystallinity of a polymer component and thus compatibility, blend morphology, and efficiency of polymer/polymer blend solar cells can be controlled by molecular design.

  4. Form-stable crystalline polymer pellets for thermal energy storage. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Botham, R.A.; Jenkins, G.H.; Ball, G.L. III; Salyer, I.O.

    1977-07-01

    The objective of this project was to develop a form-stable, crystalline polymer pellet TES bed material, useful in the 120 to 140/sup 0/C temperature range suitable for solar absorption air conditioning applications. This objective was achieved with a Si-O-Si crosslinked HDPE pellet material, demonstrated to have a high heat of fusion value (46 cal/g, approximately 98% of the HDPE's heat of fusion value prior to crosslinking). Further, on melt/freeze cycling of these TES pellets through 400 cycles in ethylene glycol, they retained nearly 100% of their initial heat of fusion value, and had excellent form-stability characteristics, with little or no inter-particle adhesion. Appropriate testing of this TES pellet material, from analytical (DSC) to a one gallon lab-scale TES unit, and finally to a 60 gallon prototype TES demonstration unit, consistently verified these results. C-C crosslinked PE products, which were slightly inferior to the Si-O-Si crosslinked PE in terms of good heat of fusion and form-stability properties, were also developed and are potential alternatives to the prime PE TES product.

  5. Obtaining Highly Crystalline Barium Sulphate Nanoparticles via Chemical Precipitation and Quenching in Absence of Polymer Stabilizers

    Directory of Open Access Journals (Sweden)

    Ángela B. Sifontes

    2015-01-01

    Full Text Available Here we report the synthesis of barium sulphate (BaSO4 nanoparticles from Ba(OH2/BaCl2 solutions by a combined method of precipitation and quenching in absence of polymer stabilizers. Transmission electron microscopy (HRTEM, Fourier transforms infrared spectroscopy (FTIR, and X-ray diffraction (XRD were employed to characterize the particles. The Scherrer formula was applied to estimate the particle size using the width of the diffraction peaks. The obtained results indicate that the synthesized material is mainly composed of nanocrystalline barite, with nearly spherical morphology, and diameters ranging from 4 to 92 nm. The lattice images of nanoparticles were clearly observed by HRTEM, indicating a high degree of crystallinity and phase purity. In addition, agglomerates with diameters between 20 and 300 nm were observed in both lattice images and dynamic light scattering measurements. The latter allowed obtaining the particle size distribution, the evolution of the aggregate size in time of BaSO4 in aqueous solutions, and the sedimentation rate of these solutions from turbidimetry measurements. A short discussion on the possible medical applications is presented.

  6. Coordination polymers built from 1,4-bis(imidazol-1-ylmethyl)benzene: from crystalline to amorphous.

    Science.gov (United States)

    Adarsh, N N; Novio, Fernando; Ruiz-Molina, Daniel

    2016-07-28

    The supramolecular chemistry of the bis-imidazole ligand 1,4-bis(imidazol-1-ylmethyl)benzene, popularly known as bix, has been explored by various researchers in order to synthesize functional coordination polymers (CPs). The flexibility of the bix ligand, its unpredictable conformation and its coordination behaviour with transition metal ions have resulted in a huge number of structurally diverse and functionally intriguing CPs. In this perspective review we discuss the progress in CPs of bix between 1997 and today. More precisely, this review emphasizes the developments in functional supramolecular coordination polymers built from the bix ligand, from crystalline materials to amorphous nanomaterials.

  7. Conductive Polymer Synthesis with Single-Crystallinity via a Novel Plasma Polymerization Technique for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2016-09-01

    Full Text Available This study proposes a new nanostructured conductive polymer synthesis method that can grow the single-crystalline high-density plasma-polymerized nanoparticle structures by enhancing the sufficient nucleation and fragmentation of the pyrrole monomer using a novel atmospheric pressure plasma jet (APPJ technique. Transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, X-ray photoelectron spectroscopy (XPS, and field emission scanning electron microscopy (FE-SEM results show that the plasma-polymerized pyrrole (pPPy nanoparticles have a fast deposition rate of 0.93 µm·min−1 under a room-temperature process and have single-crystalline characteristics with porous properties. In addition, the single-crystalline high-density pPPy nanoparticle structures were successfully synthesized on the glass, plastic, and interdigitated gas sensor electrode substrates using a novel plasma polymerization technique at room temperature. To check the suitability of the active layer for the fabrication of electrochemical toxic gas sensors, the resistance variations of the pPPy nanoparticles grown on the interdigitated gas sensor electrodes were examined by doping with iodine. As a result, the proposed APPJ device could obtain the high-density and ultra-fast single-crystalline pPPy thin films for various gas sensor applications. This work will contribute to the design of highly sensitive gas sensors adopting the novel plasma-polymerized conductive polymer as new active layer.

  8. Crystalline polymer decoration on multiwalled carbon nanotubes: MWCNT-induced P4VP periodic crystallization in CO2-expanded liquids

    Directory of Open Access Journals (Sweden)

    2011-01-01

    Full Text Available This work reports the functionalization of multi-walled carbon nanotubes (MWCNTs with crystalline poly(4- vinylpyridine (P4VP in CO2-expanded liquids (CXLs. The structure and morphology of MWCNT-induced polymer crystallization are examined, with the focus on molecular weight of P4VP (MW-P4VP, the pressure of CXLs and the concentration of P4VP. First, it is observed that the crystallization morphologies for the P4VP/MWCNTs composite with a low molecular weight P4VP (LMW-P4VP matrix could be finely controlled in CXLs, and it is surprising to find that the P4VP8700 wrapping patterns undergo a morphological evolution from dot crystals to dotted helical wrappings, and then to dense helical patterns by facile pressure tuning under lower polymer concentration. In other words, the CXLs method enables superior control of the P4VP crystallization patternings on MWCNTs, particularly efficient for LMW-P4VP at lower polymer concentration. Meanwhile, the CXL-assisted P4VP crystal growth mechanism on MWCNT is investigated, and the dominating growth mechanism is attributed to 'normal epitaxy' at lower P4VP concentration rather than 'soft epitaxy' at higher concentration. We believe that this work reports a new crystalline polymer wrapping approach in CXLs to noncovalent engineering of MWCNTs surfaces.

  9. Identification of the crystallization kinetic parameters of a semi-crystalline polymer by using PVTα measurement

    Science.gov (United States)

    Tardif, X.; Sobotka, V.; Boyard, N.; Delaunay, D.

    2011-05-01

    Injection molding is the most widely used process in the plastic industry. In the case of semi-crystalline polymer, crystallization kinetics impacts directly the quality of the piece, both on dimensional and mechanical aspects. The characterization of these kinetics is therefore of primary importance to model the process, in particular during the cooling phase. To be representative, this characterization must be carried out under conditions as close as possible to those encountered in the process: high pressure, high cooling rate, shearing, and potential presence of fibers. However, conventional apparatus such as the differential scanning calorimeter do not allow to reach these conditions. A PVTα apparatus, initially developed in the laboratory for the characterization of thermoset composites, was adapted to identify the crystallization kinetics. The aim of the presented study is to demonstrate the feasibility of the identification. This device allows the molding of a circular sample of 40 mm diameter and 6 mm thick by controlling the applied pressure on the sample and the temperature field on its surfaces. This mold is designed such as heat transfer is 1D within the thickness of the sample. It is equipped with two heat flux sensors to determine the average crystallization rate through the thickness and a displacement sensor for the determination of the volume change. The heat transfer problem between the polymer and the molding cavity is modeled by using a 1D conduction problem with a moving boundary, in which the control volume is a uniform temperature disk with a variable volume, and coupled to a crystallization kinetic model. An inverse method is used to identify the parameters of the crystallization kinetic model by minimizing an objective function based on the difference between the evolutions of the experimental and computed volume of the sample. The first validation of this methodology was to compare the kinetic parameters identified with this apparatus

  10. On the molecular anisotropy of liquid crystalline and flexible polymer systems

    Science.gov (United States)

    van Horn, Brett L.

    The demand for products of ever increasing quality or for novel applications has required increasing attention to or manipulation of the anisotropy of manufactured parts. Oriented plastics are used everywhere from recording film to automotive body parts to monofilament fishing line. Liquid crystals are also used in a wide array of applications including their dominance in the flat panel display industry, color changing temperature sensors, and woven bullet resistant fabrics. Anisotropy can also be detrimental, for instance sometimes leading to poor fracture resistance or low yield stress along specific directions. Controlling and measuring anisotropy of materials has become increasingly important, but doing so is wrought with challenges. Measuring physical properties of isotropic liquids, such as water or most oils can be done in a straightforward fashion. Their viscosities and densities, for example, have unique values under a given set of conditions. With anisotropic fluids, like liquid crystals, the viscosity, for instance, will not only depend upon temperature, concentration, etc. but also upon the direction of observation, degree of anisotropy, source of anisotropy, and so forth. This added degree of complexity complicates our ability to define the state of the material at which the measurements are made and generally necessitates the use of more sophisticated measurement strategies or techniques. This work presents techniques and tools for investigating anisotropy in liquid crystalline and stretched polymeric systems. Included are the use of conoscopy for the determination of birefringence and orientation of nematic liquid crystals and stretched polymers, the shear response of flow aligning nematic liquid crystal monodomains, and the design of a novel linear rheometer that allows for in situ optical or scattering investigations.

  11. Manufacturing, structure and properties of recycled polyethylene terephthalate /liquid crystal polymer/montmorillonite clay nanocomposites

    Science.gov (United States)

    Japins, Guntis; Berzina, Rita; Zicans, Janis; Merijs Meri, Remo; Ivanova, Tatjana; Kalkis, Valdis; Reinholds, Ingars

    2013-12-01

    Polyethylene terephthalate (PET)/liquid crystal polymer (LCP)/monthmorillonite clay (MMT) compositions were obtained by melt mixing. Their mechanical, structural, rheological and thermal properties were investigated.

  12. Current Advances in the Carbon Nanotube/Thermotropic Main-Chain Liquid Crystalline Polymer Nanocomposites and Their Blends

    Directory of Open Access Journals (Sweden)

    Lin Li

    2012-03-01

    Full Text Available Because of their extraordinary properties, such as high thermal stability, flame retardant, high chemical resistance and high mechanical strength, thermotropic liquid crystalline polymers (TLCPs have recently gained more attention while being useful for many applications which require chemical inertness and high strength. Due to the recent advance in nanotechnology, TLCPs are usually compounded with nanoparticles to form particulate composites to enhance their properties, such as barrier properties, electrical properties, mechanical properties and thermal properties. Carbon-based nanofillers such as carbon nanotube (CNT, graphene and graphene oxide are the most common fillers used for the TLCP matrices. In this review, we focus on recent advances in thermotropic main-chain liquid crystalline polymer nanocomposites incorporated with CNTs. However, the biggest challenges in the preparation of CNT/TLCP nanocomposites have been shown to be inherent in the dispersion of CNTs into the TLCP matrix, the alignment and control of CNTs in the TLCP matrix and the load-transfer between the TLCP matrix and CNTs. As a result, this paper reviews recent advances in CNT/TLCP nanocomposites through enhanced dispersion of CNTs in TLCPs as well as their improved interfacial adhesion with the TLCP matrices. Case studies on the important role of chemically modified CNTs in the TLCP/thermoplastic polymer blends are also included.

  13. A fast and reliable empirical approach for estimating solubility of crystalline drugs in polymers for hot melt extrusion formulations.

    Science.gov (United States)

    Kyeremateng, Samuel O; Pudlas, Marieke; Woehrle, Gerd H

    2014-09-01

    A novel empirical analytical approach for estimating solubility of crystalline drugs in polymers has been developed. The approach utilizes a combination of differential scanning calorimetry measurements and a reliable mathematical algorithm to construct complete solubility curve of a drug in polymer. Compared with existing methods, this novel approach reduces the required experimentation time and amount of material by approximately 80%. The predictive power and relevance of such solubility curves in development of amorphous solid dispersion (ASD) formulations are shown by applications to a number of hot-melt extrudate formulations of ibuprofen and naproxen in Soluplus. On the basis of the temperature-drug load diagrams using the solubility curves and the glass transition temperatures, physical stability of the extrudate formulations was predicted and checked by placing the formulations on real-time stability studies. An analysis of the stability samples with microscopy, thermal, and imaging techniques confirmed the predicted physical stability of the formulations. In conclusion, this study presents a fast and reliable approach for estimating solubility of crystalline drugs in polymer matrixes. This powerful approach can be applied by formulation scientists as an early and convenient tool in designing ASD formulations for maximum drug load and physical stability.

  14. Plate osteosynthesis of simple forearm fractures : LCP versus DC plates

    NARCIS (Netherlands)

    Stevens, Charles Tjerk; Ten Duis, Henk Jan

    2008-01-01

    The aim of this study was to compare the time to radiological bony union of simple A-type fractures of the forearm, treated with either a locking compression plate (LCP) or a dynamic compression plate (DCP). For each fracture, the relation between the use of compression and radiological healing time

  15. Plate osteosynthesis of simple forearm fractures : LCP versus DC plates

    NARCIS (Netherlands)

    Stevens, Charles Tjerk; Ten Duis, Henk Jan

    The aim of this study was to compare the time to radiological bony union of simple A-type fractures of the forearm, treated with either a locking compression plate (LCP) or a dynamic compression plate (DCP). For each fracture, the relation between the use of compression and radiological healing time

  16. LCP- LIFETIME COST AND PERFORMANCE MODEL FOR DISTRIBUTED PHOTOVOLTAIC SYSTEMS

    Science.gov (United States)

    Borden, C. S.

    1994-01-01

    The Lifetime Cost and Performance (LCP) Model was developed to assist in the assessment of Photovoltaic (PV) system design options. LCP is a simulation of the performance, cost, and revenue streams associated with distributed PV power systems. LCP provides the user with substantial flexibility in specifying the technical and economic environment of the PV application. User-specified input parameters are available to describe PV system characteristics, site climatic conditions, utility purchase and sellback rate structures, discount and escalation rates, construction timing, and lifetime of the system. Such details as PV array orientation and tilt angle, PV module and balance-of-system performance attributes, and the mode of utility interconnection are user-specified. LCP assumes that the distributed PV system is utility grid interactive without dedicated electrical storage. In combination with a suitable economic model, LCP can provide an estimate of the expected net present worth of a PV system to the owner, as compared to electricity purchased from a utility grid. Similarly, LCP might be used to perform sensitivity analyses to identify those PV system parameters having significant impact on net worth. The user describes the PV system configuration to LCP via the basic electrical components. The module is the smallest entity in the PV system which is modeled. A PV module is defined in the simulation by its short circuit current, which varies over the system lifetime due to degradation and failure. Modules are wired in series to form a branch circuit. Bypass diodes are allowed between modules in the branch circuits. Branch circuits are then connected in parallel to form a bus. A collection of buses is connected in parallel to form an increment to capacity of the system. By choosing the appropriate series-parallel wiring design, the user can specify the current, voltage, and reliability characteristics of the system. LCP simulation of system performance is site

  17. Fabrication of a LCP-based conductivity cell and resistive temperature device via PCB MEMS technology

    Science.gov (United States)

    Broadbent, Heather A.; Ivanov, Stanislav Z.; Fries, David P.

    2007-04-01

    Printed circuit board microelectromechanical systems are a set of fabrication techniques that use traditional inexpensive printed circuit board processes to construct microsensors. These techniques keep gaining popularity and are utilized herein. The design, fabrication and construction of a miniature, low-cost conductivity cell and resistive temperature device transducers are presented. The transducers utilize a liquid crystal polymer (LCP), a thin-film material, which exhibits moisture resistant properties that makes it suitable for aquatic applications. Novel processing techniques that are reported here include the use of a direct-write photolithography tool eliminating the use of photomasks and chemical catalytic metallization of LCP material. The rapid fabrication of these devices and the repeatability of the fabrication are demonstrated by comparing the calibration of multiple devices. The sensors' sensitivities are found to be 1082.40 ± 144.18 mS cm-1 per siemens and 5.910 ± 0.765 °C per ohm for the conductivity and temperature transducers, respectively.

  18. A Phase Field Technique for Modeling and Predicting Flow Induced Crystallization Morphology of Semi-Crystalline Polymers

    Directory of Open Access Journals (Sweden)

    Xiaodong Wang

    2016-06-01

    Full Text Available Flow induced crystallization of semi-crystalline polymers is an important issue in polymer science and engineering because the changes in morphology strongly affect the properties of polymer materials. In this study, a phase field technique considering polymer characteristics was established for modeling and predicting the resulting morphologies. The considered crystallization process can be divided into two stages, which are nucleation upon the flow induced structures and subsequent crystal growth after the cessation of flow. Accordingly, the proposed technique consists of two parts which are a flow induced nucleation model based on the calculated information of molecular orientation and stretch, and a phase field crystal growth model upon the oriented nuclei. Two-dimensional simulations are carried out to predict the crystallization morphology of isotactic polystyrene under an injection molding process. The results of these simulations demonstrate that flow affects crystallization morphology mainly by producing oriented nuclei. Specifically, the typical skin-core structures along the thickness direction can be successfully predicted. More importantly, the results reveal that flow plays a dominant part in generating oriented crystal morphologies compared to other parameters, such as anisotropy strength, crystallization temperature, and physical noise.

  19. Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template

    KAUST Repository

    Zhu, Jie

    2014-02-12

    Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules. © 2014 American Chemical Society.

  20. Towards the understanding of the molecular weight dependence of essential work of fracture in semi-crystalline polymers: A study on poly(ε-caprolactone

    Directory of Open Access Journals (Sweden)

    F. Tuba

    2014-11-01

    Full Text Available The plane-stress ductile fracture of poly(#-caprolactone (PCL has been investigated as a function of molecular weight and related crystalline structure. Because of the interacting effects in semi-crystalline polymers a separate study of a given structural parameter is rather challenging. Nevertheless, this polymer seems to be a good model material to study the effect of molecular weight on the essential work of fracture, as the interactions between the separate parameters, at room temperature, are negligible. The molecular characteristics of PCL were determined by size exclusion chromatography. To confirm the entangled molecular structure of studied polymers rheological measurements were performed. The crystalline morphology has been characterized by differential scanning calorimetry and wide angle X-ray diffraction. Quasi-static tensile tests and essential work of fracture tests were performed to study the mechanical behavior. Based on the experimental observations an empirical model has been proposed to outline the molecular weight and crystallinity dependence of the essential work of fracture in this semi-crystalline polymer.

  1. X-ray Scattering Measurements of Molecular Orientation in Channel Flows of a Thermotropic Liquid Crystalline Polymer

    Science.gov (United States)

    Cinader, D., Jr.; Burghardt, W.

    1998-03-01

    We have constructed an extrusion die which allows collection of x-ray scattering patterns(Experiments performed at DND-CAT at the APS) as a function of position in channel flows. A single-screw extruder is used to pump the melt, while interchangeable spacers allow the channel flow geometry to be altered. Available geometries include contractions and expansions of sharp and gradual character, as well as a simple slit flow. We present studies of a commercial liquid crystalline polymer (Xydar resin supplied by Amoco), emphasizing results from expansion flow experiments. A sharp decrease in orientation is observed at the expansion, followed by a recovery in the straight downstream channel. Scattering patterns reveal orientation transverse to the flow direction induced by unfavorable extensional gradients. This mixed orientation state manifests itself as a Rfour spotS scattering pattern consisting of two sets of nematic peaks with axes aligned perpendicular to one another.(Work sponsored by an AFOSR MURI)

  2. Short-Range Order of Mesomorphic Phase of a Semi-crystalline Polymer by Solid-State NMR: Isotactic Polypropylene

    Science.gov (United States)

    Yuan, Shichen; Miyoshi, Toshikazu

    2015-03-01

    Mesophase is intermediate phase between crystalline and melt state. Characterization of short-range structures of disordered mesomorphic phase without long-range order is challenging issue in polymer characterization. The short range order was considered same as α or β i PP, or neither. In this work, a new strategy using 13C-13C through space interactions as well as molecular dynamics based on chemical shift anisotropy (CSA) re-orientation is proposed for evaluating short-range order of mesophase of isotactic-polypropylene (iPP). 13C-13C double quantum (DQ) build up curves of 13C 15 percent CH3 selectively labeled iPP and spin dynamics simulations elucidate that local packing structures in mesophase is very close to that in β phase. Moreover, exchange NMR proves that the crystalline chains perform large amplitude motions in all α, β, and mesophase. The correlation time of overall dynamics of stems in mesophase follows the same Arrhenius line with that of β phase but is largely deviated from the Arrhenius line of the α phase. Through the obtained results, it is concluded that short-range order in mesophase is exceedingly close or same to those in β phase. This work was financially supported by the National Science Foundation (Grant No. DMR-1105829) and by UA startup funds.

  3. Synthesis of Isothianaphthene (ITN and 3,4-Ethylenedioxy-Thiophene (EDOT-Based Low-Bandgap Liquid Crystalline Conjugated Polymers

    Directory of Open Access Journals (Sweden)

    Hiromasa Goto

    2013-05-01

    Full Text Available Copolymers, consisting of isothianaphthene and phenylene derivatives with liquid crystal groups, were synthesized via Migita-Kosugi-Stille polycondensation reaction. IR absorption, UV-vis optical absorption, and PL spectroscopy measurements were carried out. Thermotropic liquid crystallinity of the polymers with bandgap of ~2.5 eV was confirmed.

  4. On the "Tertiary Structure" of Poly-Carbenes; Self-Assembly of sp(3)-Carbon-Based Polymers into Liquid-Crystalline Aggregates

    NARCIS (Netherlands)

    Franssen, Nicole M. G.; Ensing, Bernd; Hegde, Maruti; Dingemans, Theo J.; Norder, Ben; Picken, Stephen J.; van Ekenstein, Gert O. R. Alberda; van Eck, Ernst R. H.; Elemans, Johannes A. A. W.; Vis, Mark; Reek, Joost N. H.; de Bruin, Bas

    2013-01-01

    The self-assembly of poly(ethylidene acetate) (st-PEA) into van der Waals-stabilized liquid-crystalline (LC) aggregates is reported. The LC behavior of these materials is unexpected, and unusual for flexible sp(3)-carbon backbone polymers. Although the dense packing of polar ester functionalities al

  5. On the “Tertiary Structure” of Poly-Carbenes; Self-Assembly of sp3-Carbon-Based Polymers into Liquid-Crystalline Aggregates

    NARCIS (Netherlands)

    Franssen, N.G.M.; Ensing, B.; Hegde, M.; Dingemans, T.J.; Norder, B.; Picken, S.J.; Alberda van Ekenstein, G.O.R.; van Eck, E.R.H.; Elemans, J.A.A.W; Vis, M.; Reek, J.N.H.; de Bruin, B.

    2013-01-01

    The self-assembly of poly(ethylidene acetate) (st-PEA) into van der Waals-stabilized liquid-crystalline (LC) aggregates is reported. The LC behavior of these materials is unexpected, and unusual for flexible sp(3)-carbon backbone polymers. Although the dense packing of polar ester functionalities al

  6. Solvent-mediated amorphous-to-crystalline transformation of nitrendipine in amorphous particle suspensions containing polymers

    DEFF Research Database (Denmark)

    Xia, Dengning; Wu, Jian-Xiong; Cui, Fude;

    2012-01-01

    quantitatively determined using image analysis based on polarized light microscopy. The findings from the image analysis revealed that the transformation process occurred through the dissolution of amorphous drug precipitate followed by the nucleation and growth of the crystalline phase with the amorphous....... However, a further increase in drug concentration to 100mg/ml decelerated the growth of nitrendipine crystals. Combining image analysis of polarized light micrographs together with Raman spectroscopy and XRPD provided an in-depth insight into solid state transformations in amorphous nitrendipine...

  7. Liquid crystalline polymer networks based on a nematic epoxy resin with azoxy group

    Science.gov (United States)

    Włodarska, M.; Mossety-Leszczak, B.; Bąk, G. W.; Galina, H.; Ledzion, R.

    2009-06-01

    The paper presents research results on curing two recently synthesized liquid crystalline epoxy materials with selected amines. The process of cross-linking, the final product of curing, and the pure monomers were examined using polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and dielectric spectroscopy (DS). Chemical structure of the products was confirmed using spectroscopic methods. The authors attempted to demonstrate how selection of curing conditions (such as the amine used as curing agent, the curing temperature or preparation of the surface in contact with the sample) influences optical properties of the cured product.

  8. High-crystalline medium-band-gap polymers consisting of benzodithiophene and benzotriazole derivatives for organic photovoltaic cells.

    Science.gov (United States)

    Kim, Ji-Hoon; Song, Chang Eun; Shin, Nara; Kang, Hyunbum; Wood, Sebastian; Kang, In-Nam; Kim, Bumjoon J; Kim, Bongsoo; Kim, Ji-Seon; Shin, Won Suk; Hwang, Do-Hoon

    2013-12-26

    Two semiconducting conjugated polymers were synthesized via Stille polymerization. The structures combined unsubstituted or (triisopropylsilyl)ethynyl (TIPS)-substituted 2,6-bis(trimethylstannyl)benzo[1,2-b:4.5-b']dithiophene (BDT) as a donor unit and benzotriazole with a symmetrically branched alkyl side chain (DTBTz) as an acceptor unit. We investigated the effects of the different BDT moieties on the optical, electrochemical, and photovoltaic properties of the polymers and the film crystallinities and carrier mobilities. The optical-band-gap energies were measured to be 1.97 and 1.95 eV for PBDT-DTBTz and PTIPSBDT-DTBTz, respectively. Bulk heterojunction photovoltaic devices were fabricated and power conversion efficiencies of 5.5% and 2.9% were found for the PTIPSBDT-DTBTz- and PBDT-DTBTz-based devices, respectively. This difference was explained by the more optimal morphology and higher carrier mobility in the PTIPSBDT-DTBTz-based devices. This work demonstrates that, under the appropriate processing conditions, TIPS groups can change the molecular ordering and lower the highest occupied molecular orbital level, providing the potential for improved solar cell performance.

  9. Shape Memory Polymers from Blends of Elastomers and Crystalline Small Molecules

    Science.gov (United States)

    Cavicchi, Kevin; Brostowitz, Nicole; Hukill, Brent; Fairbairn, Heather

    2015-03-01

    This talk will present work on the fabrication of shape memory polymers (SMPs) by swelling natural with molten fatty acids. By this method a SMPs with excellent shape fixity and recovery can be obtained during free recovery after uniaxial deformation to 100% strain. Experiments to measure the shape memory properties under both stress and strain controlled conditions will be reported and compared. This fabrication method offers a number of advantages for preparing SMPs. First, it utilizes natural rubber as the base material for the SMP, which capitalizes on a high performance, commodity elastomer. Second, by blending a commercial polymer with a small molecule additive no additional chemistry is needed for the preparation of the SMP. Third, this route inverts the typically processing steps by crosslinking the permanent network prior to formation of the physically crosslinked reversible network. This offers a means to potentially generate a SMP from any preformed elastomeric article.

  10. Birefringence-dependent linearly-polarized emission in a liquid crystalline organic light emitting polymer.

    Science.gov (United States)

    Lee, Dong-Myoung; Lee, You-Jin; Kim, Jae-Hoon; Yu, Chang-Jae

    2017-02-20

    We investigated the linearly polarized emission of uniformly aligned poly(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thia-diazol-4,8-diyl) (F8BT) with a liquid crystalline phase on a rubbed alignment layer. The polarization ratio, defined by the ratio of luminous intensities polarized parallel and perpendicular to the rubbed direction, gradually decreased with increasing thickness of the F8BT film. In the photoluminescence (PL) process, the polarized light is emitted throughout the whole F8BT film, while in the electroluminescence (EL) process, the polarized light is emitted at a certain region within the F8BT film. The thickness-dependent polarization ratios in both PL and EL processes were successfully described based on a simple model wherein the mean optical birefringence was expressed as a function of the thickness of the F8BT film.

  11. Effect of crystalline microstructure on the photophysical performance of polymer/perylene composite films

    Institute of Scientific and Technical Information of China (English)

    封伟; 徐友龙; 易文辉; 周峰; 王晓工; 吉野勝美

    2003-01-01

    To obtain high carrier mobility, better charge injection capability, and high photovoltaic device conversion efficiency, a powerful strategy is to improve the morphology of the polymer/dye composite films. Conjugated conducting polymer (CP) thin films doped with perylene derivative (PV) of various concentrations were prepared by spin-casting method, and their morphology and photovoltaic characteristics were examined. The change in morphology and molecular reorientation occurring in CP-PV composite films upon annealing at different temperatures was investigated using scanning electron microscopy, x-ray diffraction, Fourier transform infrared and UV-vis absorption. By changing the annealing temperature, PV microcrystallines of 8-10μm in size lying parallel to the substrate surface can be obtained.Annealing effect improved the photovoltaic performance of ITO/CP-PV/A1 Schottky-type solar cells, which can be attributed to the formation of an electron conducting PV crystal network. Preliminary studies indicate that the morphological structure in CP-PV composite films has an important influence to their photovoltaic properties.

  12. Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules.

    Science.gov (United States)

    Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo

    2017-02-01

    Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Study on ion conductivity and crystallinity of composite polymer electrolytes based on poly(ethylene oxide)/poly(acrylonitrile) containing nano-sized Al2O3 fillers.

    Science.gov (United States)

    Kim, Mingyeong; Lee, Lyungyu; Jung, Yongju; Kim, Seok

    2013-12-01

    In this paper, composite polymer electrolytes were prepared by a blend of poly(ethylene oxide) (PEO) and poly(acrylonitrile) (PAN) as a polymer matrix, ethylene carbonate as a plasticizer, LiClO4 as a salt, and by containing a different content of nano-sized Al2O3. The composite films were prepared by using the solution casting method. The crystallinity and ionic conductivity of the polymer electrolytes was investigated using X-ray diffraction (XRD) and AC impedance method, respectively. The morphology of composite polymer electrolyte film was analyzed by SEM method. From the experimental results, by increasing the Al2O3 content, the crystallinity of PEO was reduced, and the ionic conductivity was increased. In particular, by a doping of 15 wt.% Al2O3 in PEO/PAN polymer blend, the CPEs showed the superior ionic conductivity. However, when Al2O3 content exceeds 15 wt.%, the ionic conductivity was decreased. From the surface morphology, it was concluded that the ionic conductivity was decreased because the CPEs showed a heterogenous morphology due to immiscibility or aggregation of the ceramic filler within the polymer matrix.

  14. 液晶高分子流体在拉伸流动中拉伸粘度的解析计算研究%Computational Analytical Approach to Extensional Viscosity of Liquid Crystalline Polymer in Extensional Flow

    Institute of Scientific and Technical Information of China (English)

    付强

    2008-01-01

    The shearing extension is a main factor in the extrusion process of LC polymer melt. Using the constitutive equation of LCP-B for LC polymer melts and solutions, the influence of orientational motion on extensional viscosity is studied. The change curves of dimensionless extensional viscosity with relaxation time and shear rate have been obtained.%在液晶高分子熔液挤出过程中,剪切拉伸是主要考虑因素.用液晶高分子B模型本构方程,并考虑取向运动的影响得到拉伸粘度随松驰时间与拉伸率之间的变化关系和曲线.

  15. SRG Inscription in Supramolecular Liquid Crystalline Polymer Film: Replacement of Mesogens

    Directory of Open Access Journals (Sweden)

    Shun Mitsui

    2017-02-01

    Full Text Available The photoinduced surface relief formation via mass transfer upon irradiation with patterned light has long been a subject of extensive investigation. In azobenzene-containing liquid crystalline materials, UV light irradiation that generates the cis isomer leads to the liquid crystal to isotropic photochemical transition. Due to this phase change, efficiency of the mass transfer to generate a surface relief grating (SRG becomes markedly greater. We have previously indicated that azobenzene-colored SRG-inscribed film can be bleached by removing a hydrogen-bonded azobenzene mesogen. However, this process largely reduces the height feature of the SRG corrugation. Herein, we propose an extended procedure where a colorless mesogen is filled successively after the removal of the azobenzene side chain. The process involves four stages: (i SRG inscription in a hydrogen-bonded supramolecular azobenzene material; (ii crosslinking (insolubilization of the SRG film; (iii removal of azobenzene mesogen by rinsing with a solvent, and (iv stuffing the hollow film with a different mesogen. Although the final stuffing stage was insufficient at the present stage, this work demonstrates the possibility and validity of the strategy of mesogen replacement.

  16. Polymer Vesicles as Robust Scaffolds for the Directed Assembly of Highly Crystalline Nanocrystals †

    KAUST Repository

    Wang, Mingfeng

    2009-12-15

    We report the incorporation of various inorganic nanoparticles (NPs) (PbS, LaOF, LaF3, and TiO2, each capped by oleic acid, and CdSe/ZnS core/shell QDs capped by trioctylphosphine oxide) into vesicles (d = 70-150 nm) formed by a sample of poly(styrene-b-acrylic acid) (PS4o4-b-PAA 62, where the subscripts refer to the degree of polymerization) in mixtures of tetrahydrofuran (THF), dioxane, and water. The block copolymer formed mixtures of crew-cut micelles and vesicles with some enhancement of the vesicle population when the NPs were present. The vesicle fraction could be isolated by selective sedimentation via centrifugation, followed by redispersion in water. The NPs appeared to be incorporated into the PAA layers on the internal and external walls of the vesicles (strongly favoring the former). NPs on the exterior surface of the vesicles could be removed completely by treating the samples with a solution of ethylenediaminetetraacetate (EDTA) in water. The triangular nanoplatelets of LaF3 behaved differently. Stacks of these platelets were incorporated into solid colloidal entities, similar in size to the empty vesicles that accompanied them, during the coassembly as water was added to the polymer/LaF3/THF/ dioxane mixture. © 2009 American Chemical Society.

  17. Solubilities of crystalline drugs in polymers: an improved analytical method and comparison of solubilities of indomethacin and nifedipine in PVP, PVP/VA, and PVAc.

    Science.gov (United States)

    Sun, Ye; Tao, Jing; Zhang, Geoff G Z; Yu, Lian

    2010-09-01

    A previous method for measuring solubilities of crystalline drugs in polymers has been improved to enable longer equilibration and used to survey the solubilities of indomethacin (IMC) and nifedipine (NIF) in two homo-polymers [polyvinyl pyrrolidone (PVP) and polyvinyl acetate (PVAc)] and their co-polymer (PVP/VA). These data are important for understanding the stability of amorphous drug-polymer dispersions, a strategy actively explored for delivering poorly soluble drugs. Measuring solubilities in polymers is difficult because their high viscosities impede the attainment of solubility equilibrium. In this method, a drug-polymer mixture prepared by cryo-milling is annealed at different temperatures and analyzed by differential scanning calorimetry to determine whether undissolved crystals remain and thus the upper and lower bounds of the equilibrium solution temperature. The new annealing method yielded results consistent with those obtained with the previous scanning method at relatively high temperatures, but revised slightly the previous results at lower temperatures. It also lowered the temperature of measurement closer to the glass transition temperature. For D-mannitol and IMC dissolving in PVP, the polymer's molecular weight has little effect on the weight-based solubility. For IMC and NIF, the dissolving powers of the polymers follow the order PVP > PVP/VA > PVAc. In each polymer studied, NIF is less soluble than IMC. The activities of IMC and NIF dissolved in various polymers are reasonably well fitted to the Flory-Huggins model, yielding the relevant drug-polymer interaction parameters. The new annealing method yields more accurate data than the previous scanning method when solubility equilibrium is slow to achieve. In practice, these two methods can be combined for efficiency. The measured solubilities are not readily anticipated, which underscores the importance of accurate experimental data for developing predictive models.

  18. Amphiphilic Cross-Linked Liquid Crystalline Fluoropolymer-Poly(ethylene glycol) Coatings for Application in Challenging Conditions: Comparative Study between Different Liquid Crystalline Comonomers and Polymer Architectures.

    Science.gov (United States)

    Zigmond, Jennifer S; Letteri, Rachel A; Wooley, Karen L

    2016-12-14

    Linear and hyperbranched poly(ethylene glycol)-cross-linked amphiphilic fluoropolymer networks comprised of different liquid crystalline comonomers were developed and evaluated as functional coatings in extreme weather-challenging conditions. Through variation of the liquid-crystalline comonomer and hydrophilic:hydrophobic component ratios, several series of coatings were synthesized and underwent a variety of analyses including differential scanning calorimetry, water contact angle measurements and solution stability studies in aqueous media. These materials maintained an unprecedented reduction in the free water melting transition (Tm) temperature across the hyperbranched and linear versions. The coatings synthesized from hyperbranched fluoropolymers preserved the liquid crystalline character of the mesogenic components, as seen by polarized optical microscopy, and demonstrated stability in saltwater aqueous environments and in cold weather conditions.

  19. Study of LCP based flexible patch antenna array

    KAUST Repository

    Ghaffar, Farhan A.

    2012-07-01

    Wrapping of a two element LCP based patch antenna array is studied in this work. For the first time, the designed array is bent in both E and H planes to observe the effect on the radiation and impedance performance of the antenna. The 38 GHz simulation results reveal better performance for H plane bending as compared to E plane bending. A 100 um thick substrate is used for the design which is best suited for flexible antenna applications. Gain variations of 1.1 dB and 1.4 dB are observed for the two orientations while a significantly increased impedance bandwidth of 3 % is obtained with H plane wrapping. The design is highly suitable for broadband micro-cellular backhaul applications. © 2012 IEEE.

  20. Combined main-chain/side-chain ionic liquid crystalline polymer based on ‘jacketing’ effect: Design, synthesis, supra-molecular self-assembly and photophysical properties

    Directory of Open Access Journals (Sweden)

    L. Weng

    2015-06-01

    Full Text Available Reasonably fabricating ordered structures of ionic polymers is very important for the development of novel functional materials. By combining the ions and liquid cry stalline polymer, we successfully designed and synthesized a series of novel combined main-chain/side-chain ionic liquid crystalline polymer (MCSC-ILCPs containing imidazolium groups and different counter-anions, poly (2,5-bis{[6-(4-butoxy-4'-imidazolium biphenylhexyl]oxycarbonyl}styrene salts poly(BImBHCS-X with the following types of counter-anions (Br¯, BF4¯, PF6¯ and TFSI¯. Combined technologies confirmed the chemical structures of the monomers and polymers with imidazolium cation and different counter-anions. Differential scanning calorimetry (DSC, polarized light microscopy (PLM and one- and two-dimensional wide-angle X-ray diffraction (1D and 2D WAXD results illustrated that the LC structures and the transitions of ordered structures depended on the nature of the counter-anion employed. The polymers with Br¯ and BF4¯ counter-anions exhibited smectic A (SmA LC behavior below the isotropic temperature. The another one, poly(BImBHCS–TFSI with the large volume of the TFSI¯ anion destroyed the packing of the LC ordered structure resulting in an amorphous structure. The photophysical properties of the polymers prepared can be adjusted by tuning the ionic interaction of the polymers by switching the counter-anion.

  1. The importance of orientation in proton transport of a polymer film based on an oriented self-organized columnar liquid-crystalline polyether

    Energy Technology Data Exchange (ETDEWEB)

    Tylkowski, Bartosz; Castelao, Nuria [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Giamberini, Marta, E-mail: marta.giamberini@urv.net [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Garcia-Valls, Ricard [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Reina, Jose Antonio [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, Carrer Marcel.li Domingo s/n, E-43007, Tarragona (Spain); Gumi, Tania [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain)

    2012-02-01

    We prepared membranes based on a liquid-crystalline side-chain polyether obtained by chemical modification of commercial poly(epichlorohydrin) (PECH) with dendrons. This polymer exhibited a columnar structure, which could form an ion channel in the inner part. The columns were successfully oriented by taking advantage of surface interactions between the polymer and hydrophilic substrates, as confirmed by X-ray diffraction analysis (XRD), environmental scanning electron microscopy (ESEM) and optical microscopy between crossed polars (POM). Column orientation was found to be crucial for effective transport: the oriented membranes exhibited proton transport comparable to that of Nafion Registered-Sign N117 and no water uptake. An increase in sodium ion concentration in the feed phase suggested a proton/cation antiport. On the contrary, no proton transport was detected on unoriented membranes based on the same liquid-crystalline side-chain polyether or on unmodified PECH. - Highlights: Black-Right-Pointing-Pointer We prepared oriented membranes based on a liquid crystalline columnar polyether. Black-Right-Pointing-Pointer In this structure, the inner polyether chain could work as an ion channel. Black-Right-Pointing-Pointer We obtained membranes by casting a chloroform solution in the presence of water. Black-Right-Pointing-Pointer Membranes showed good proton permeability due to the presence of oriented channels.

  2. PVD Silicon Carbide as a Thin Film Packaging Technology for Antennas on LCP Substrates for Harsh Environments

    Science.gov (United States)

    Scardelletti, Maximilian C.; Stanton, John W.; Ponchak, George E.; Jordan, Jennifer L.; Zorman, Christian A.

    2010-01-01

    This paper describes an effort to develop a thin film packaging technology for microfabricated planar antennas on polymeric substrates based on silicon carbide (SiC) films deposited by physical vapor deposition (PVD). The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on liquid crystal polymer (LCP) substrates. The PVD SiC thin films were deposited directly onto the antennas by RF sputtering at room temperature at a chamber pressure of 30 mTorr and a power level of 300 W. The SiC film thickness is 450 nm. The return loss and radiation patterns were measured before and after the SiC-coated antennas were submerged into perchloric acid for 1 hour. No degradation in RF performance or physical integrity of the antenna was observed.

  3. LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    XinJiu Wang; Qi-Feng Zhou

    2005-01-01

    @@ "Their book is a most useful resource for approaching a large literature that even a specialist needs help to assimilate. It covers many widely separated areas - synthetic chemistry to theoretical physics, fundamental science to applications."

  4. Guidelines for the clinical application of the LCP.

    Science.gov (United States)

    Gautier, Emanuel; Sommer, Christoph

    2003-11-01

    The Locking Compression Plate (LCP), in combination with the LISS and the PHILOS, is part of a new plate generation requiring an adapted surgical technique and new thinking about commonly used concepts of internal fixation using plates. The following guidelines are needed to avoid failures and possible complications in the hands of surgeons not yet confident with the new implant philosophy. The importance of the reduction technique and minimal-invasive plate insertion and fixation is addressed to keep bone viability undisturbed. Understanding of mechanical background for choosing the proper implant length and the type and number of screws is essential to obtain a sound fixation with a high plate span ratio and a low plate screw density. A high plate span ration decreases the load onto the plate. A high working length of the plate in turn reduces the screw loading, thus fewer screws need to be inserted and the plate screw density can be kept low. Knowledge of the working length of the screw is helpful for the proper choice of monocortical or bicortical screws. Selection is done according to the quality of the bone structure and is important to avoid problems at the screw thread bone interface with potential pullout of screws and secondary displacement. Conclusive rules are given at the end of this chapter.

  5. Biomass enzymatic saccharification is determined by the non-KOH-extractable wall polymer features that predominately affect cellulose crystallinity in corn.

    Science.gov (United States)

    Jia, Jun; Yu, Bin; Wu, Leiming; Wang, Hongwu; Wu, Zhiliang; Li, Ming; Huang, Pengyan; Feng, Shengqiu; Chen, Peng; Zheng, Yonglian; Peng, Liangcai

    2014-01-01

    Corn is a major food crop with enormous biomass residues for biofuel production. Due to cell wall recalcitrance, it becomes essential to identify the key factors of lignocellulose on biomass saccharification. In this study, we examined total 40 corn accessions that displayed a diverse cell wall composition. Correlation analysis showed that cellulose and lignin levels negatively affected biomass digestibility after NaOH pretreatments at pbiomass saccharification after pretreatments with NaOH and H2SO4 at three concentrations. Notably, despite that the non-KOH-extractable residues covered 12%-23% hemicelluloses and lignin of total biomass, their wall polymer features exhibited the predominant effects on biomass enzymatic hydrolysis including Ara substitution degree of xylan (reverse Xyl/Ara) and S/G ratio of lignin. Furthermore, the non-KOH-extractable polymer features could significantly affect lignocellulose crystallinity at pbiomass digestibility. Hence, this study could suggest an optimal approach for genetic modification of plant cell walls in bioenergy corn.

  6. Carbon/Liquid Crystal Polymer Prepreg for Cryogenic and High-Temp Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — KaZaK Composites proposes to develop a pultrusion process to produce carbon fiber / liquid crystal polymer (LCP) prepreg, a first for this category of materials and...

  7. Influence of crystallinity and energetics on charge separation in polymer-inorganic nanocomposite films for solar cells.

    Science.gov (United States)

    Bansal, Neha; Reynolds, Luke X; MacLachlan, Andrew; Lutz, Thierry; Ashraf, Raja Shahid; Zhang, Weimin; Nielsen, Christian B; McCulloch, Iain; Rebois, Dylan G; Kirchartz, Thomas; Hill, Michael S; Molloy, Kieran C; Nelson, Jenny; Haque, Saif A

    2013-01-01

    The dissociation of photogenerated excitons and the subsequent spatial separation of the charges are of crucial importance to the design of efficient donor-acceptor heterojunction solar cells. While huge progress has been made in understanding charge generation at all-organic junctions, the process in hybrid organic:inorganic systems has barely been addressed. Here, we explore the influence of energetic driving force and local crystallinity on the efficiency of charge pair generation at hybrid organic:inorganic semiconductor heterojunctions. We use x-ray diffraction, photoluminescence quenching, transient absorption spectroscopy, photovoltaic device and electroluminescence measurements to demonstrate that the dissociation of photogenerated polaron pairs at hybrid heterojunctions is assisted by the presence of crystalline electron acceptor domains. We propose that such domains encourage delocalization of the geminate pair state. The present findings suggest that the requirement for a large driving energy for charge separation is relaxed when a more crystalline electron acceptor is used.

  8. CHARACTERIZATION OF γ-IRRADIATED CRYSTALLINE POLYMERS Ⅱ ISOTHERMAL CRYSTALLIZATION KINETICS OF γ-RADIATION INDUCED CROSSLINKED POLYAMIDE 1010

    Institute of Scientific and Technical Information of China (English)

    FENG Jinhua; ZHANG Lihua; CHEN Donglin

    1989-01-01

    Polyamide 1010 is a γ-radiation crosslinkable polymer. After irradiation, it is possible to raise its service temperature up to 240 ℃ . Network formation greatly changes the crystallization behaviour of the polymer. In the present work, DSC was used to examine its isothermal crystallization kinetics. It is found that in addition to the necessity of more undercooling and the lowering of crystallization rate, the primary crystallization stage of the irradiated polymer is shortened. This effect is more evident with increasing radiation dose and content of enhanced difunctional crosslinking agent. However, the crystallization mechanism of the primary stage is not changed as evidenced by the constancy of Avrami exponent. The lamella end surface free energy σe calculated according to Hoffman's equation is very sensitive to γ- radiation. It increases abruptly in 2 - 3 fold even though theradiation dose is not high enough. The origin of this phenomenon may be accounted for in terms of network structure of the polymer.

  9. Solvent-dependent self-assembly and ordering in slow-drying semi-crystalline conjugated polymer solutions

    KAUST Repository

    Zhao, Kui

    2015-09-07

    The mechanistic understanding of the intrinsic molecular self-assembly of conjugated polymers is of immense importance to controlling the microstructure development in organic semiconducting thin films, with meaningful impact on charge transport and optoelectronic properties. Yet, to date the vast majority of studies have focused on the fast solution process itself, with studies of slower intrinsic molecular self-assembly in formulations lagging behind. Here we have investigated molecular self-assembly during spontaneous organization and uncovered how changes in formulation influence the microstructure, morphology and transport properties of conjugated polymer thin films. Our results suggest that the polymer-solvent interaction is the key factor for the molecular self-assembly and changes in macroscopic charge transport, which is in contrast with most solution processes, such as spin-coating and blade coating, where solvent drying kinetics dominates the aggregation and crystallization processes. Energetically favourable interactions between the polymer and its solvent are shown to cause chain expansion, resulting in a large hydrodynamic volume and few chain entanglements in solution. This provides molecular freedom for self-assembly and is shown to greatly enhance the local and long range order of the polymer, intra-chain backbone planarity and crystallite size. These improvements, in turn, are shown to endow the conjugated polymer with high carrier transport, as demonstrated by organic thin film transistors.

  10. Photoinduced dichroism and optical anisotropy in a liquid-crystalline azobenzene side chain polymer caused by anisotropic angular distribution of trans and cis isomers

    Science.gov (United States)

    Blinov, Lev M.; Kozlovsky, Mikhail V.; Ozaki, Masanori; Skarp, Kent; Yoshino, Katsumi

    1998-10-01

    Photochromism has been studied for two comb-like liquid-crystalline copolymers (I) and (II) containing azobenzene chromophores in their side chains. In a smectic glass phase of both copolymers, upon short-time irradiation by UV light, long-living cis isomers are observed. Both copolymers manifest the photoinduced anisotropy, the physical mechanisms of which seem to be quite different. In spin-coated films of polymer (II), the origin of the anisotropy is a strong stable dichroism, which is due to an enrichment and depletion of the chosen angular direction, correspondingly, with trans and cis isomers of the azobenzene chromophores. Polymer (I) manifests no dichroism at all, and its induced optical anisotropy may be accounted for by a rather slow chromophore reorientation. In copolymer (II) a considerable reorientation of the mesogenic groups also occurs as a secondary phenomenon at the stage of the cis isomer formation only. This observation shed more light on the general process of the light-induced molecular reorientation in polymers, liquid crystals, and Langmuir-Blodgett films, which is of great importance for holographic information recording.

  11. Controlled thermal expansion printed wiring boards based on liquid crystal polymer dielectrics

    Science.gov (United States)

    Knoll, Thomas E.; Blizard, Kent; Jayaraj, K.; Rubin, Leslie S.

    1994-01-01

    Dielectric materials based on innovative Liquid Crystal Polymers (LCP's) have been used to fabricate surface mount printed wiring boards (PWB's) with a coefficient of thermal expansion matched to leadless ceramic chip carriers. Proprietary and patented polymer processing technology has resulted in self reinforcing material with balanced in-plane mechanical properties. In addition, LCP's possess excellent electrical properties, including a low dielectric constant (less than 2.9) and very low moisture absorption (less than 0.02%). LCP-based multilayer boards processed with conventional drilling and plating processes show improved performance over other materials because they eliminate the surface flatness problems of glass or aramid reinforcements. Laser drilling of blind vias in the LCP dielectric provides a very high density for use in direct chip attach and area array packages. The material is ideally suited for MCM-L and PCMCIA applications fabricated with very thin dielectric layers of the liquid crystal polymer.

  12. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

    Directory of Open Access Journals (Sweden)

    Amid Ranjkesh

    2015-12-01

    Full Text Available We propose a highly oriented photochromic dye film for an ultraviolet (UV-sensing layer, where spirooxazine (SO derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation.

  13. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing.

    Science.gov (United States)

    Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

    2015-12-29

    We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation.

  14. Biomass enzymatic saccharification is determined by the non-KOH-extractable wall polymer features that predominately affect cellulose crystallinity in corn.

    Directory of Open Access Journals (Sweden)

    Jun Jia

    Full Text Available Corn is a major food crop with enormous biomass residues for biofuel production. Due to cell wall recalcitrance, it becomes essential to identify the key factors of lignocellulose on biomass saccharification. In this study, we examined total 40 corn accessions that displayed a diverse cell wall composition. Correlation analysis showed that cellulose and lignin levels negatively affected biomass digestibility after NaOH pretreatments at p<0.05 & 0.01, but hemicelluloses did not show any significant impact on hexoses yields. Comparative analysis of five standard pairs of corn samples indicated that cellulose and lignin should not be the major factors on biomass saccharification after pretreatments with NaOH and H2SO4 at three concentrations. Notably, despite that the non-KOH-extractable residues covered 12%-23% hemicelluloses and lignin of total biomass, their wall polymer features exhibited the predominant effects on biomass enzymatic hydrolysis including Ara substitution degree of xylan (reverse Xyl/Ara and S/G ratio of lignin. Furthermore, the non-KOH-extractable polymer features could significantly affect lignocellulose crystallinity at p<0.05, leading to a high biomass digestibility. Hence, this study could suggest an optimal approach for genetic modification of plant cell walls in bioenergy corn.

  15. Biomass Enzymatic Saccharification Is Determined by the Non-KOH-Extractable Wall Polymer Features That Predominately Affect Cellulose Crystallinity in Corn

    Science.gov (United States)

    Wu, Leiming; Wang, Hongwu; Wu, Zhiliang; Li, Ming; Huang, Pengyan; Feng, Shengqiu; Chen, Peng; Zheng, Yonglian; Peng, Liangcai

    2014-01-01

    Corn is a major food crop with enormous biomass residues for biofuel production. Due to cell wall recalcitrance, it becomes essential to identify the key factors of lignocellulose on biomass saccharification. In this study, we examined total 40 corn accessions that displayed a diverse cell wall composition. Correlation analysis showed that cellulose and lignin levels negatively affected biomass digestibility after NaOH pretreatments at pbiomass saccharification after pretreatments with NaOH and H2SO4 at three concentrations. Notably, despite that the non-KOH-extractable residues covered 12%–23% hemicelluloses and lignin of total biomass, their wall polymer features exhibited the predominant effects on biomass enzymatic hydrolysis including Ara substitution degree of xylan (reverse Xyl/Ara) and S/G ratio of lignin. Furthermore, the non-KOH-extractable polymer features could significantly affect lignocellulose crystallinity at pbiomass digestibility. Hence, this study could suggest an optimal approach for genetic modification of plant cell walls in bioenergy corn. PMID:25251456

  16. Mesomorphous structure change by tail chain number in ionic liquid crystalline complexes of linear polymer and amphiphiles

    Institute of Scientific and Technical Information of China (English)

    Zhi Yu Cheng; Bi Ye Ren; Shu Ying He; Xin Xing Liu; Zhen Tong

    2011-01-01

    Three polymer-amphiphile complexes were prepared by combining poly(allylamine hydrochloride) (PAH) with the potassium salt of mono-, di-, and trisubstituted benzoic acid dendrons (4-octyloxybenzoic acid, 3,5-dioctyloxybenzoic acid, and 3,4,5-trioctyloxybenzoic acid). The solid structure and properties were monitored with FT-IR, XRD, TG, DSC, and polarized optical microscope (POM). Difference in the tail chain number of the dendritic amphiphile induced two different mesomorphous structures: lamella for the mono-, disubstituted dendron containing complexes and hexagonal column for the trisubstituted dendron containing complexes. These corresponded to the ionic thermotropic liquid crystal SmA and φh phases, respectively. This finding is significant for design of functional nanostructures based on the ionic complexation of polymers and amphiphiles.

  17. Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics

    Science.gov (United States)

    Paternò, G. M.; Robbiano, V.; Fraser, K. J.; Frost, C.; García Sakai, V.; Cacialli, F.

    2017-01-01

    Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications. PMID:28112195

  18. Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics

    Science.gov (United States)

    Paternò, G. M.; Robbiano, V.; Fraser, K. J.; Frost, C.; García Sakai, V.; Cacialli, F.

    2017-01-01

    Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications.

  19. Irreversible volume growth in polymer-bonded powder systems: effects of crystalline anisotropy, particle size distribution, and binder strength

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A; Gee, R H; Hoffman, D; Fried, L E

    2007-08-22

    Pressed-powdered crystallites of intrinsically anisotropic materials have been shown to undergo irreversible volume expansion when subjected to repeated cycles of heating and cooling. We develop a coarse-grained (micron-scale) interaction Hamiltonian for this system and perform molecular dynamics simulations, which quantitatively reproduce the experimentally observed irreversible growth. The functional form and values of the interaction parameters at the coarse-grained level are motivated by our knowledge at the atomic/molecular scale, and allows a simple way to incorporate the effect of polymeric binder. We demonstrate that irreversible growth happens only in the presence of intrinsic crystalline anisotropy of the powder material, is mediated by particles much smaller than the average crystallite size, and can be significantly reduced in the presence of high-strength polymeric binder with elevated glass transition temperatures.

  20. Understanding the roles of nanoparticle dispersion and polymer crystallinity in controlling the mechanical properties of HA/PHBV nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Noohom, Wadcharawadee; Jack, Kevin S; Martin, Darren; Trau, Matt, E-mail: k.jack@uq.edu.a [Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Queensland 4072 (Australia)

    2009-02-15

    Nano-sized hydroxyapatite (HA) particles stabilized using poly(acrylic acid) (PAA) as a dispersing agent, and sonic energy to further increase dispersion, were blended with poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) using a precipitation/gelation method to produce HA/PHBV nanocomposites with up to 16% by weight of HA content. The level of HA nanoparticle dispersion was monitored in the precursor dispersions prior to composite production and in the nanocomposites by a range of techniques including visual observation, turbidity measurements and electron microscopy, and the roles of the dispersing agent and the sonic energy in controlling the dispersion of HA particles in both the precursor dispersions and the final composites as well as their effects on the compressive strength and Young's modulus were investigated. It was found that HA suspensions treated with both PAA and sonic energy possessed significantly better colloidal stability compared to untreated suspensions or suspensions treated with either PAA or sonic energy. This, in turn, resulted in better dispersion of HA nanoparticles in the composites and higher compressive moduli as a function of the particle loading. This enhancement in stiffness of the composites was attributed primarily to the increased surface area of the HA filler in the more highly dispersed samples, but also to an observed increase in the crystalline content achievable after annealing of the samples. It is proposed that this increase in crystallinity is due to the more highly dispersed particles acting as nucleation sites for the crystallization of the PHBV at the particle interface, which, in turn, leads to enhancement of the bonding between the matrix and filler.

  1. Concentrator bifacial crystalline silicon solar cells with multi-wire metallization attached to TCO layers using transparent conductive polymers

    Science.gov (United States)

    Untila, Gennady; Chebotareva, Alla; Kost, Tatiana; Salazkin, Sergei; Shaposhnikova, Vera; Shvarts, Maxim

    2017-09-01

    Replacing expensive silver with inexpensive copper for the metallization of silicon wafer solar cells can lead to substantial reductions in material costs associated with cell production. A promising approach is the use of multi-wire design. This technology uses many wires in the place of busbars, and the copper wires are "soldered" during the low-temperature lamination process to the fingers (printed or plated) or to the transparent conductive oxide (TCO) layer, e.g. in the case of the α-Si/c-Si heterojunction cells. Here we describe a solar cell design in which wires are attached to TCO layers using transparent conductive polymer (TCP) films. To this end, we have synthesized a number of thermoplastics, poly(arylene ether ketone) copolymers (co-PAEKs), containing phthalide in their main chain. The fraction of phthalide-containing units in the copolymers was p = 3, 5, 15, and 50 mol %. With increasing p, the peak strain temperature of the co-PAEKs rises from 205 to 290 °C and their optical band gap and refractive index increase from 3.12 to 3.15 eV and from 1.6 to 1.614, respectively. The copolymers have a negligible absorption coefficient in the wavelength range 400- 1100 nm. When exposed to an excess pressure of 1 atm or above, co-PAEK films less than 30 µm in thickness undergo a transition from a dielectric to a conductive state. The resistivity (ρC) of wire/TCP/TCO (ITO = In2O3:Sn and IFO = In2O3:F) contacts ranges from 0.37 to 1.43 mΩ cm2. The polymer with the highest phthalide content (p = 50 mol %) has the lowest ρC. The average work of adhesion per unit area determined by pulling off the wires from the polymer surface depends on both the phthalide content of the co-PAEKs and their reduced viscosity, ranging from 14.3 to 43.5 N/cm. The highest value was obtained for the co-PAEK with p = 50 mol %. We have fabricated low-concentration bifacial IFO/(n+pp+)Cz-Si/ITO solar cells with a wire contact grid attached to IFO and ITO using a co-PAEK film. The

  2. Formation of nanoparticles during melt mixing a thermotropic liquid crystalline polyester and sulfonated polystyrene ionomers

    Science.gov (United States)

    Lee, Hyuksoo; Zhu, Lei; Weiss, R. A.

    2006-03-01

    The formation of nanoparticles and the mechanism of their formation in a blend of a thermotropic liquid crystalline polyester (LCP) and the zinc salt of a lightly sulfonated polystyrene ionomer (Zn-SPS) were investigated using Fourier transform infrared, thermogravimetric analysis, and gas chromatograph-mass spectroscopy. Transmission electron microscopy and wide-angle X-ray scattering were used to study the morphology of the blends and structure of nanoparticles. The origin of nanoparticle formation appeared to be related to the development of phenyl acetate chain ends on the LCP that arose due to a chemical reaction between the LCP and residual catalytic amounts of zinc-acetate and/or acetic acid that were present from the neutralization step in the preparation of the ionomer. The origin of formation and kinetics of the nano-particle formation and the mechanical and rheological properties of these nanocomposites are briefly discussed.

  3. Mesomorphic ionic hyperbranched polymers: effect of structural parameters on liquid-crystalline properties and on the formation of gold nanohybrids

    Science.gov (United States)

    Nguyen, Hong Hanh; Serrano, Clara Valverde; Lavedan, Pierre; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Viguerie, Nancy Lauth-De; Marty, Jean-Daniel

    2014-03-01

    Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex.Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex. Electronic supplementary information (ESI) available: NMR, DSC, POM and SAXS data for hyperbranched complexes and associated hybrids. See DOI: 10.1039/c3nr05913h

  4. Miniaturized and Ferrite Based Tunable Bandpass Filters in LCP and LTCC Technologies for SoP Applications

    KAUST Repository

    Arabi, Eyad A.

    2015-04-01

    Wireless systems with emerging applications are leaning towards small size, light-weight and low cost. Another trend for these wireless devices is that new applications and functionalities are being added without increasing the size of the device. To accomplish this, individual components must be miniaturized and the system should be designed to maximize the integration of the individual components. The high level of 3D integration feasible in system on package design (SoP) concept can fulfill the latter requirement. Bandpass filters are important components on all wireless systems to reject the unwanted signals and reduce interference. Being mostly implemented with passive and distributed components, bandpass filters take considerable space in a wireless system. Moreover, with emerging bands and multiple applications encompassed in a single device, many bandpass filters are required. The miniaturization related to bandpass filters can be approached by three main ways: (1) at the component level through the miniaturization of individual bandpass filters, (2) at the system level through the use of tunable filters to reduce the overall number of filters, and (3) at the system level through the high level of integration in a 3D SoP platform. In this work we have focused on all three aspects of miniaturization of band pass filters mentioned above. In the first part of this work, a low frequency (1.5 GHz global positioning system (GPS) band) filter implemented through 3D lumped components in two leading SoP technologies, namely low temperature co-fired ceramic (LTCC) and the liquid crystal polymers (LCP) is demonstrated. The miniaturized filter is based on a second order topology, which has been modified to improve the selectivity and out-of-band rejection without increasing the size. Moreover, for the case of LCP, the filter is realized in an ultra-thin stack up comprising four metallization layers with an overall thickness of only 100 _m. Due to its ultra

  5. A p-adaptive LCP formulation for the compressible Navier-Stokes equations

    Science.gov (United States)

    Cagnone, J. S.; Vermeire, B. C.; Nadarajah, S.

    2013-01-01

    This paper presents a polynomial-adaptive lifting collocation penalty (LCP) formulation for the compressible Navier-Stokes equations. The LCP formulation is a high-order nodal scheme in differential form. This format, although computationally efficient, complicates the treatment of non-uniform polynomial approximations. In Cagnone and Nadarajah (2012) [9], we proposed to circumvent this difficulty by employing specially designed elements inserted at the interface where the interpolation degree varies. In the present study we examine the applicability of this approach to the discretization of the Navier-Stokes equations, with focus put on the treatment of the viscous fluxes. The stability of the scheme is analyzed with the scalar diffusion equation and the merits of the approach are demonstrated with various p-adaptive simulations.

  6. 3D lumped components and miniaturized bandpass filter in an ultra-thin M-LCP for SOP applications

    KAUST Repository

    Arabi, Eyad A.

    2013-01-01

    In this work, a library of 3D lumped components completely embedded in the thinnest, multilayer LCP (M-LCP) stack- up with four metallization layers and 100 μm of total thickness, is reported for the first time. A vertically and horizontally interdigitated capacitor, realized in this stack-up, provides higher self resonant frequency as compared to a similarly sized conventional parallel plate capacitor. Based on the above mentioned library, a miniaturized bandpass filter is presented for the GPS application. It utilizes mutually coupled inductors and is the smallest reported in the literature with a size of (0.035×0.028×0.00089)λg. Finally, the same filter realized in a competing ceramic technology (LTCC) is compared in performance with the ultra-thin M-LCP design. The M-LCP module presented in this work is inherently exible and offers great potential for wearable and conformal applications.

  7. The effect of injection molding conditions on the near-surface rubber morphology, surface chemistry, and adhesion performance of semi-crystalline and amorphous polymers

    Science.gov (United States)

    Weakley-Bollin, Shannon Christine

    This thesis investigated the effect of injection molding processing variables, resin formulation and mold material on the resulting morphology and properties of semi-crystalline and amorphous polymers in parts molded on large presses with fully developed flow. Five different polymer resins and two different coating types were investigated, and the near-surface morphology was found to be dependent on material formulation, processing parameters, and geometry. For painted TPO, changes in the near-surface rubber morphology and surface chemistry based on material and processing conditions had no significant effect on the adhesion performance. For metal plated ABS, the adhesion performance was found to be heavily dependent on the rubber surface morphology, which varied with material formulation and processing conditions. One of the most significant findings was that forged aluminum injection molding tooling had little effect on the surface morphology or adhesion performance of either polypropylene or the two TPO formulations examined, despite the five-fold increase in thermal conductivity over traditional tool steel. Surface chemistry, however, was found to be affected by cooling rate, depending on material formulation. A UV stabilizer additive was found concentrated at 2.5 atomic percent on the surface of the aluminum molded part, but not the steel molded part, demonstrating a possible opportunity for using additives and aluminum tooling to create "designer surfaces". Processing conditions were found to have a competing role in metal plated ABS, where conditions that lowered surface stress and improved adhesion by a factor of 15 also increased the amount of bulk molded-in stress by nearly 7%. Both factors were found to play an important role in adhesion performance due to the effect of surface stress on the quality of the resulting etch structure. The bulk stress must be minimized to due to the large mechanical and thermal mismatch between the polymer and metal layers

  8. A study on the mechanical characteristics of the EBM-printed Ti-6Al-4V LCP plates in vitro.

    Science.gov (United States)

    Liu, Peng-Cheng; Yang, Yun-Ji; Liu, Run; Shu, He-Xi; Gong, Jin-Peng; Yang, Yong; Sun, Qi; Wu, Xing; Cai, Ming

    2014-11-05

    The electron beam melting (EBM) Ti-6Al-4V material technology has been developed over a short time period. It was introduced through a research to develop Ti-6Al-4V implants for patients, but EBM printed locking compression plates have not been used for clinical implants. The main purpose of this study is to find whether the EBM Ti-6Al-4V plate suit for clinical implants. First, we scanned an AO-locking compression plate (LCP) and printed LCP samples using EBM. Next, we evaluated the EBM plate surface roughness through optical microscopy as well as the LCP and EBM plates' mechanical characteristics using the ASTM standard, which is commonly used to test the mechanical properties of bone plates subject to bending. Each sample was examined using a single-cycle four-point bending test and hardness testing to acquire data on bending stiffness, bending strength, bending structural stiffness, and hardness. The results show significant differences in bending stiffness, bending strength, bending structural stiffness, and hardness between the samples using EBM and the original LCP plates. The EBM-printed samples' surface roughness was 0.49 ± 0.02 μm. The mean hardness of the LCP sample was 266.67 HV10 ± 5.8, and the EBM-printed sample mean hardness was 341.1 HV10 ± 1.93. The EBM samples' bending stiffness was 87.67%, which is greater than using the LCP plates'; and the bending strength was 190.7% greater, the bending structural stiffness was 73.2% greater, and the hardness was 27.9% greater. The results show that the EBM plates' general mechanical strength was significantly greater than the LCP plates. An EBM plate is advantageous for clinical implants because it can be customized with great potential for improvement.

  9. Potential of a newly developed high-speed near-infrared (NIR) camera (Compovision) in polymer industrial analyses: monitoring crystallinity and crystal evolution of polylactic acid (PLA) and concentration of PLA in PLA/Poly-(R)-3-hydroxybutyrate (PHB) blends.

    Science.gov (United States)

    Ishikawa, Daitaro; Nishii, Takashi; Mizuno, Fumiaki; Sato, Harumi; Kazarian, Sergei G; Ozaki, Yukihiro

    2013-12-01

    This study was carried out to evaluate a new high-speed hyperspectral near-infrared (NIR) camera named Compovision. Quantitative analyses of the crystallinity and crystal evolution of biodegradable polymer, polylactic acid (PLA), and its concentration in PLA/poly-(R)-3-hydroxybutyrate (PHB) blends were investigated using near-infrared (NIR) imaging. This NIR camera can measure two-dimensional NIR spectral data in the 1000-2350 nm region obtaining images with wide field of view of 150 × 250 mm(2) (approximately 100  000 pixels) at high speeds (in less than 5 s). PLA with differing crystallinities between 0 and 50% blended samples with PHB in ratios of 80/20, 60/40, 40/60, 20/80, and pure films of 100% PLA and PHB were prepared. Compovision was used to collect respective NIR spectra in the 1000-2350 nm region and investigate the crystallinity of PLA and its concentration in the blends. The partial least squares (PLS) regression models for the crystallinity of PLA were developed using absorbance, second derivative, and standard normal variate (SNV) spectra from the most informative region of the spectra, between 1600 and 2000 nm. The predicted results of PLS models achieved using the absorbance and second derivative spectra were fairly good with a root mean square error (RMSE) of less than 6.1% and a determination of coefficient (R(2)) of more than 0.88 for PLS factor 1. The results obtained using the SNV spectra yielded the best prediction with the smallest RMSE of 2.93% and the highest R(2) of 0.976. Moreover, PLS models developed for estimating the concentration of PLA in the blend polymers using SNV spectra gave good predicted results where the RMSE was 4.94% and R(2) was 0.98. The SNV-based models provided the best-predicted results, since it can reduce the effects of the spectral changes induced by the inhomogeneity and the thickness of the samples. Wide area crystal evolution of PLA on a plate where a temperature slope of 70-105 °C had occurred was also

  10. MANAGEMENT OF DISTAL DIA PHYSI O METAPHYSEAL J UNCTION HUMERUS FRACTURES WITH SINGLE COLUMN POSTEROLATERAL LCP - OUR RESULTS

    Directory of Open Access Journals (Sweden)

    Lokesh Chowdary

    2015-03-01

    Full Text Available Fracture of the distal humerus are complex and challenging injuries to treat. In this study we used d istal humeral posterolateral LCP system, which is an anatomically shaped angular stable system. The purpose of this retrospective study was to evaluate clinical outcome after ORIF with posterolateral LCP plate. METHODS: 24 Consecutive patients with distal humerus fractures treated with posterolateral LCP between October 2010 to December 2014 . 20 patients had complete follow up of 20 months , patients evaluated both clinically & radiologically & VAS & DASH score were used. RESULTS: All patients except 4 r e gained full range of movements , 2 patients lost 5° of extension & 1 patient 10° of extension. No loss of flexion in any patient. One patient had failed fixation who had stated early manual labour.

  11. Determination of Crystallinity and Crystal Structure of Hylamer™ Polyethylene after in vivo Wear

    OpenAIRE

    Visentin, M; Stea, S.; De Clerico, M.; Reggiani, M.; Fagnano, C.; Squarzoni, S.; De Toni, A

    2006-01-01

    Abstract Hylamer? polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer? components used in joint prostheses, if sterilized ...

  12. Determination of Crystallinity and Crystal Structure of Hylamer™ Polyethylene after in vivo Wear

    OpenAIRE

    Visentin, M; Stea, S.; Clerico, M; Reggiani, M.; Fagnano, C.; Squarzoni, S.; Toni, A.

    2006-01-01

    Abstract Hylamer? polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer? components used in joint prostheses, if sterilized ...

  13. Micromachining of liquid crystal polymer film with frequency converted diode-pumped Nd:YVO4 laser

    Science.gov (United States)

    Li, Mingwei; Hix, Ken; Dosser, Larry R.; Hartke, Kevin; Blackshire, Jim

    2003-07-01

    Liquid crystal polymer (LCP) is a new and innovative material being used as an alternative to polyimide in the flexible circuit industry. LCP has many intrinsic benefits over polyimide including lower moisture absorption and improved dimensional stability. However, LCP is very resistant to chemical milling or etching. As a result, other methods for processing the material are being investigated including laser micromachining. In this paper, three frequency converted diode-pumped solid-state (DPSS) Nd:YVO4 lasers at 355 nm were used to micromachine a LCP film and a copper/LCP laminate. Of them, two are Q-switched lasers operating in the nanosecond regime and the other a mode-locked laser in the picosecond regime. The Q-switched lasers can be operated at pulse repetition rates of 1 to 300 kHz while the mode-locked system is operated at 80 MHz. The micromachining experiments consisted of cutting the 50 μm thick LCP film, cutting the 18 μm thick copper on the film, and drilling micro-vias through both the copper coating and the film substrate. The laser/material interactions and processing speeds were studied and compared. The results show that, compared to polyimide film of the same thickness, LCP film can be more efficiently processed by laser micromachining. In addition, each laser has a unique advantage in processing LCP based flexible circuit materials. The Q-switched lasers are more capable of processing the copper coating while the mode-locked laser can cut LCP film faster with the smallest kerf width.

  14. Users Manual for the Program LCP2 (Version 2.40)

    DEFF Research Database (Denmark)

    Gaunholt, Hans

    1996-01-01

    LCP2 (Linear Circuit Program) is developed as an analysis and optimization tool to be used in the design of passive, active and digital filters with arbitrary structures. By the aid of an optimization loop the program may be used to solve nonlinear design equations for active filter structures...... or to compensate designs for the application of nonideal circuit components such as transmission lines with losses and nonideal operational amplifiers. The information needed by the program is some target responses such as the poles and zeros or tabulated responses of e.g. the magnitude and the group-delay. Output...... is a set of corrected component values according to a minimum of some error-function. The error function may be chosen to be of the least square, the least "2p", the minimax and the L1-norm type. Sensitivity information is available from the program together with the worst-case sensitivity index...

  15. Microfluidic formation of pH responsive 5CB droplets decorated with PAA-b-LCP.

    Science.gov (United States)

    Khan, Waliullah; Choi, Jin Ho; Kim, Gyu Man; Park, Soo-Young

    2011-10-21

    We are reporting for the first time the pH responsiveness of liquid crystal (LC) microdroplets decorated with an amphiphilic block copolymer of PAA-b-LCP. We successfully demonstrated the adsorption of block copolymer on LC droplets by fluorescence microscopy and pH response to the radial-to-bipolar orientational change of the LC droplets by changing pH from 12 to 2 through the polarized optical microscope (POM). We believe that our results may pave the way for the generation of monodisperse droplets decorated by various amphiphilic block copolymers which respond to several kinds of the external stimuli. These developments may be important for potential applications of the LC droplets in sensing and encapsulation fields.

  16. The elastic properties of crystalline syndiotactic polypropylene

    Directory of Open Access Journals (Sweden)

    Paul Unwin

    1998-01-01

    Full Text Available The ability to predict the ultimate mechanical stiffness of a polymer is of considerable value because this provides a good indication of the effort which might justifiably be expended either in polymer synthesis or in polymer engineering to produce optimum polymer structures. Generally, the best mechanical properties are identified with those of the crystalline structure, so the problem is essentially one of measuring or predicting the crystal properties.

  17. Short-term supplementation of low-dose gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), or GLA plus ALA does not augment LCP omega 3 status of Dutch vegans to an appreciable extent

    NARCIS (Netherlands)

    Fokkema, M R; Brouwer, D A; Hasperhoven, M B; Martini, I A; Muskiet, F A

    2000-01-01

    Vegans do not consume meat and fish and have therefore low intakes of long chain polyunsaturated fatty acids (LCP). They may consequently have little negative feedback inhibition from dietary LCP on conversion of alpha -linolenic acid (ALA) to the LCP omega 3 eicosapentaenoic (EPA) and docosahexaeno

  18. Short-term supplementation of low-dose gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), or GLA plus ALA does not augment LCP omega 3 status of Dutch vegans to an appreciable extent

    NARCIS (Netherlands)

    Fokkema, M R; Brouwer, D A; Hasperhoven, M B; Martini, I A; Muskiet, F A

    2000-01-01

    Vegans do not consume meat and fish and have therefore low intakes of long chain polyunsaturated fatty acids (LCP). They may consequently have little negative feedback inhibition from dietary LCP on conversion of alpha -linolenic acid (ALA) to the LCP omega 3 eicosapentaenoic (EPA) and

  19. Oligo(ethylene glycol)-incorporated hybrid linear alkyl side chains for n-channel polymer semiconductors and their effect on the thin-film crystalline structure.

    Science.gov (United States)

    Kim, Ran; Kang, Boseok; Sin, Dong Hun; Choi, Hyun Ho; Kwon, Soon-Ki; Kim, Yun-Hi; Cho, Kilwon

    2015-01-28

    Oligo(ethylene glycol)-incorporated hybrid linear alkyl side chains, serving as solubilizing groups, are designed and introduced into naphthalene-diimide-based n-channel copolymers. The synthesized polymers exhibit unipolar n-type operation with an electron mobility of up to 1.64 cm(2) V(-1) s(-1), which demonstrates the usefulness of the hybrid side chains in polymer electronics applications.

  20. Organic Field-Effect Transistors Based on a Liquid-Crystalline Polymeric Semiconductor using SU-8 Gate Dielectrics onFlexible Substrates

    Directory of Open Access Journals (Sweden)

    Kornelius Tetzner

    2014-10-01

    Full Text Available In this work, the insulating properties of poly(4-vinylphenol (PVP and SU-8 (MicroChem, Westborough, MA, USA dielectrics are analyzed and compared with each other. We further investigate the performance behavior of organic field-effect transistors based on a semiconducting liquid-crystal polymer (LCP using both dielectric materials and evaluate the results regarding the processability. Due to the lower process temperature needed for the SU-8 deposition, the realization of organic transistors on flexible substrates is demonstrated showing comparable charge carrier mobilities to devices using PVP on glass. In addition, a µ-dispensing procedure of the LCP on SU-8 is presented, improving the switching behavior of the organic transistors, and the promising stability data of the SU-8/LCP stack are verified after storing the structures for 60 days in ambient air showing negligible irreversible degradation of the organic semiconductor.

  1. Evaluation of the surface chemistry and drug-polymer interaction of semi-crystalline micro-particles for the development of controlled release formulations.

    Science.gov (United States)

    Mithu, Sadeque H; Haque, Syed N; Chowdhry, Babur Z; Nokhodchi, Ali; Maniruzzaman, Mohammed

    2017-07-01

    This research work explores the surface chemistry and drug-polymer interaction in the manufactured controlled release micro-particles. Isoniazid (INH) was used as a model anti-tubercular drug while Eudragit® S100 (S100), Eudragit® L100-55 based co-processed Acryl EZE (EZE) and Ethylcellulose ECN10 (ECN10) were used as polymeric carriers. INH containing micro-particles were prepared using a mini spray dryer B-290 (Buchi, Switzerland). The drug polymer ratios were optimized at 1:1 and 1:3 to evaluate the effect of polymers on the release of the drug from the micro-particles. Solid state characterization via SEM and particle size analysis of the manufactured micro-particles showed densely aggregated spherical particles with a mean diameter particles. The physico-chemical characterization carried out by using DSC and XRPD showed an increase in the amorphicity of the drug during the spray drying process while the chemical elemental analysis via XPS revealed a strong intermolecular interaction between the amine group of the drug and the carboxyl group of the polymers. As expected, the in vitro dissolution study showed a slow release pattern for the highly water soluble drug INH in acidic media (pH1.2) for the first 2h followed by a burst release upon changing the pH to 6.8. It was concluded that emerging spray drying processing can be used as a valuable tool to encapsulate drug for controlled release dosage forms by means of facilitating a possible drug/polymer interaction as outlined by novel XPS analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Bietti's Crystalline Dystrophy

    Science.gov (United States)

    ... Dystrophy > Facts About Bietti's Crystalline Dystrophy Facts About Bietti's Crystalline Dystrophy This information was developed by the ... is the best person to answer specific questions. Bietti’s Crystalline Dystrophy Defined What is Bietti’s Crystalline Dystrophy? ...

  3. Influences of guide-tube and bluff-body on advanced atmospheric pressure plasma source for single-crystalline polymer nanoparticle synthesis at low temperature

    Science.gov (United States)

    Kim, Dong Ha; Park, Choon-Sang; Kim, Won Hyun; Shin, Bhum Jae; Hong, Jung Goo; Park, Tae Seon; Seo, Jeong Hyun; Tae, Heung-Sik

    2017-02-01

    The use of a guide-tube and bluff-body with an advanced atmospheric pressure plasma source is investigated for the low-temperature synthesis of single-crystalline high-density plasma polymerized pyrrole (pPPy) nano-materials on glass and flexible substrates. Three process parameters, including the position of the bluff-body, Ar gas flow rate, and remoteness of the substrate from the intense and broadened plasma, are varied and examined in detail. Plus, for an in-depth understanding of the flow structure development with the guide-tube and bluff-body, various numerical simulations are also conducted using the same geometric conditions as the experiments. As a result, depending on both the position of the bluff-body and the Ar gas flow rate, an intense and broadened plasma as a glow-like discharge was produced in a large area. The production of the glow-like discharge played a significant role in increasing the plasma energy required for full cracking of the monomers in the nucleation region. Furthermore, a remote growth condition was another critical process parameter for minimizing the etching and thermal damage during the plasma polymerization, resulting in single- and poly-crystalline pPPy nanoparticles at a low temperature with the proposed atmospheric pressure plasma jet device.

  4. Neutron scattering as a probe of liquid crystal polymer-reinforced composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, R.P.; Douglas, E.P.; Benicewicz, B.C.; Langlois, D.A.

    1995-12-31

    This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This research project sought to obtain nanoscale and molecular level information on the mechanism of reinforcement in liquid crystal polymer (LCP)-reinforced composites, to realize molecular-reinforced LCP composites, and to test the validity of the concept of molecular reinforcement. Small-angle neutron scattering was used to study the structures in the ternary phase diagram of LCP with liquid crystal thermosets and solvent on length scales ranging from 1-100 nm. The goal of the scattering measurements is to understand the phase morphology and degree of segregation of the reinforcing and matrix components. This information helps elucidate the physics of self assembly in these systems. This work provides an experimental basis for a microengineering approach to composites of vastly improved properties.

  5. LCP crystallization and X-ray diffraction analysis of VcmN, a MATE transporter from Vibrio cholerae

    Energy Technology Data Exchange (ETDEWEB)

    Kusakizako, Tsukasa [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Tanaka, Yoshiki [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192 (Japan); Hipolito, Christopher J. [Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575 (Japan); Kuroda, Teruo [Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Ishitani, Ryuichiro [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Suga, Hiroaki [Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nureki, Osamu, E-mail: nureki@bs.s.u-tokyo.ac.jp [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2016-06-22

    A V. cholerae MATE transporter was crystallized using the lipidic cubic phase (LCP) method. X-ray diffraction data sets were collected from single crystals obtained in a sandwich plate and a sitting-drop plate to resolutions of 2.5 and 2.2 Å, respectively. Multidrug and toxic compound extrusion (MATE) transporters, one of the multidrug exporter families, efflux xenobiotics towards the extracellular side of the membrane. Since MATE transporters expressed in bacterial pathogens contribute to multidrug resistance, they are important therapeutic targets. Here, a MATE-transporter homologue from Vibrio cholerae, VcmN, was overexpressed in Escherichia coli, purified and crystallized in lipidic cubic phase (LCP). X-ray diffraction data were collected to 2.5 Å resolution from a single crystal obtained in a sandwich plate. The crystal belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 52.3, b = 93.7, c = 100.2 Å. As a result of further LCP crystallization trials, crystals of larger size were obtained using sitting-drop plates. X-ray diffraction data were collected to 2.2 Å resolution from a single crystal obtained in a sitting-drop plate. The crystal belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 61.9, b = 91.8, c = 100.9 Å. The present work provides valuable insights into the atomic resolution structure determination of membrane transporters.

  6. Sterilization of propylene/ethylene random copolymers: Annealing effects on crystalline structure and transparency as influenced by polymer structure and nucleation

    Directory of Open Access Journals (Sweden)

    2011-09-01

    Full Text Available An extensive investigation of three different series of isotactic ethylene/propylene (EP random copolymers was performed to understand the factors influencing the change in optical properties in the steam sterilization of extrusion cast films from such materials. Different analytical methods (differential scanning calorimetry (DSC, X-ray diffraction and electron microscopy were employed to elucidate structural changes determining film optics, and in addition to the polymer structure parameters also nucleation and processing effects were studied. The findings clearly show that a combination of homogeneously randomized comonomer distribution and nucleation can partly inhibit lamellar thickening in sterilization, thus preserving high transparency even after a heat treatment. In detail, attention has to be paid to the combined effects of primary and secondary post-crystallization, which both are affected by the chain regularity.

  7. Bio-based liquid crystalline polyesters

    Science.gov (United States)

    Wilsens, Carolus; Rastogi, Sanjay; Dutch Collaboration

    2013-03-01

    The reported thin-film polymerization has been used as a screening method in order to find bio-based liquid crystalline polyesters with convenient melting temperatures for melt-processing purposes. An in depth study of the structural, morphological and chemical changes occurring during the ongoing polycondensation reactions of these polymers have been performed. Structural and conformational changes during polymerization for different compositions have been followed by time resolved X-ray and Infrared spectroscopy. In this study, bio-based monomers such as vanillic acid and 2,5-furandicarboxylic acid are successfully incorporated in liquid crystalline polyesters and it is shown that bio-based liquid crystalline polymers with high aromatic content and convenient processing temperatures can be synthesized. Special thanks to the Dutch Polymer Institute for financial support

  8. Crystalline Confinement

    CERN Document Server

    Banerjee, D; Jiang, F -J; Wiese, U -J

    2013-01-01

    We show that exotic phases arise in generalized lattice gauge theories known as quantum link models in which classical gauge fields are replaced by quantum operators. While these quantum models with discrete variables have a finite-dimensional Hilbert space per link, the continuous gauge symmetry is still exact. An efficient cluster algorithm is used to study these exotic phases. The $(2+1)$-d system is confining at zero temperature with a spontaneously broken translation symmetry. A crystalline phase exhibits confinement via multi-stranded strings between charge-anti-charge pairs. A phase transition between two distinct confined phases is weakly first order and has an emergent spontaneously broken approximate $SO(2)$ global symmetry. The low-energy physics is described by a $(2+1)$-d $\\mathbb{R}P(1)$ effective field theory, perturbed by a dangerously irrelevant $SO(2)$ breaking operator, which prevents the interpretation of the emergent pseudo-Goldstone boson as a dual photon. This model is an ideal candidat...

  9. Liquid crystalline thermosetting polyimides. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, A.E.; Huang, S.J. [Connecticut Univ., Storrs, CT (United States). Inst. of Materials Science

    1993-07-01

    Phase separation of rodlike reinforcing polymers and flexible coil matrix polymers is a common problem in formulating molecular composites. One way to reduce phase separation might be to employ liquid crystalline thermosets as the matrix material. In this work, functionally terminated polyimide oligomers which exhibit lyotropic liquid crystalline behavior were successfully prepared. Materials based on 2,2{prime}-bis(trifluoromethyl)-4,4{prime}-diaminobiphenyl and 3,3{prime},4,4{prime}-biphenylenetetra-carboxylic dianhydride have been synthesized and characterized.

  10. 纳米微晶纤维/聚乙烯醇复合薄膜的制备及性能%Preparation and Property of Composite Films of Nano-Crystalline Cellulose/Polymer-Poly Vinyl Alcohol

    Institute of Scientific and Technical Information of China (English)

    田景阳; 朱琦; 张璠; 黄崇杏; 杨崎峰

    2012-01-01

    Films of Nano-Crystalline Cellulose/Polymer-Polyv inyl Alcohol(NCC/PVA) with different NCC content were obtained through the sol/gel process ,and NCC with 20 - 50nm particle size was obtained from bagasse. The influnce of NCC content on composite films was fucosed 'on. The results show that these composite films have improved thermal stability with the adding of NCC. The composite films' tensile strength increased 115% and water absorption reduced 12.0% and elongation ruduced 68% when the content of NCC was 0.5%.%采用蔗渣为原料制备出粒径大小为20~50nm的纳米微晶纤维素(NCC),并用溶胶/凝胶方法制备出不同NCC含量的纳米微晶纤维素/聚乙烯醇(NCC/PVA)复合薄膜,重点研究了NCC加入量对复合薄膜综合性能的影响。结果表明,NCC的加入能使薄膜的热稳定性有所提高,当NCC的添加量在0.5%时,聚乙烯醇薄膜的拉伸强度提高了115%,吸水性降低了12.0%,断裂伸长率减少了68%。

  11. 35Cl NQR study of lattice dynamic and magnetic property of a crystalline coordination polymer {CuCA(phz)(H 2O) 2} n

    Science.gov (United States)

    Gotoh, Kazuma; Terao, Takeshi; Asaji, Tetsuo

    2007-01-01

    Copper(II) compounds {CuCA(phz)(H 2O) 2} n (H 2CA = chloranilic acid, phz = phenazine) having a layer structure of -CuCA(H 2O) 2- polymer chains and phenazine were studied by 35Cl nuclear quadrupole resonance (NQR). The single NQR line observed at 35.635 MHz at 261.5 K increased to 35.918 MHz at 4.2 K. The degree of reduction of electric field gradient due to lattice vibrations was similar to that of chloranilic acid crystal. Temperature dependence of spin-lattice relaxation time, T1, of the 35Cl NQR signal below 20 K, between 20 and 210 K, and above 210 K, was explained by (1) a decrease of effective electron-spin density caused by antiferromagnetic interaction, (2) a magnetic interaction between Cl nuclear-spin and electron-spins on paramagnetic Cu(II) ions, and (3) an increasing contribution from reorientation of ligand molecules, respectively. The electron spin-exchange parameter ∣ J∣ between the neighboring Cu(II) electrons was estimated to be 0.33 cm -1 from the T1 value of the range 20-210 K. Comparing this value with that of J = -1.84 cm -1 estimated from the magnetic susceptibility, it is suggested that the magnetic dipolar coupling with the electron spins on Cu(II) ions must be the principal mechanism for the 35Cl NQR spin-lattice relaxation of {CuCA(phz)(H 2O) 2} n but a delocalization of electron spin over the chloranilate ligand has to be taken into account.

  12. Polymer blends

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Naik, Sanjeev

    2017-08-22

    The present invention provides, among other things, extruded blends of aliphatic polycarbonates and polyolefins. In one aspect, provided blends comprise aliphatic polycarbonates such as poly(propylene carbonate) and a lesser amount of a crystalline or semicrystalline polymer. In certain embodiments, provided blends are characterized in that they exhibit unexpected improvements in their elongation properties. In another aspect, the invention provides methods of making such materials and applications of the materials in applications such as the manufacture of consumer packaging materials.

  13. Structural Analysis of Aromatic Liquid Crystalline Polyesters

    Directory of Open Access Journals (Sweden)

    Arpad Somogyi

    2011-01-01

    Full Text Available Laboratory preparations of liquid crystalline prepolymers, distillates accompanying prepolymers, final polymers, and sublimates accompanying final polymers were examined. NaOD/D2O depolymerization of prepolymers and polymers back to monomers with integration of the 1H NMR spectra showed up to 6% excess of carboxyls over phenol groups, caused partly by loss of the low-boiling comonomer hydroquinone through distillation during prepolymerization and leaving anhydride units in the polymer chain. ESI− MS and MS/MS of hexafluoroisopropanol extracts of the prepolymer detected small molecules including some containing anhydride groups; ESI+ MS showed the presence of small cyclic oligomers. 1H NMR (including TOCSY spectra provided more quantitative analyses of these oligomers. The final polymerization increases the length of the polymer chains and sublimes out the small oligomers. Anhydride linkages remaining in the polymer must make LCP’s more susceptible to degradation by nucleophilic reagents such as water, alkalis, and amines.

  14. Impaired maternal glucose homeostasis during pregnancy is associated with low status of long-chain polyunsaturated fatty acids (LCP) and essential fatty acids (EFA) in the fetus

    NARCIS (Netherlands)

    Dijck-Brouwer, DAJ; Hadders-Algra, M; Bouwstra, H; Decsi, T; Boehm, G; Martini, IA; Boersma, ER; Muskiet, FAJ

    2005-01-01

    Low status of long-chain polyunsaturated fatty acids (LCP) and essential fatty acids (EFA) in the fetus is associated with less favorable neonatal neurological condition. A 'relative', rather than 'absolute' EFA deficiency might explain this finding. A relative EFA deficiency may derive from impaire

  15. Impaired maternal glucose homeostasis during pregnancy is associated with low status of long-chain polyunsaturated fatty acids (LCP) and essential fatty acids (EFA) in the fetus

    NARCIS (Netherlands)

    Dijck-Brouwer, DAJ; Hadders-Algra, M; Bouwstra, H; Decsi, T; Boehm, G; Martini, IA; Boersma, ER; Muskiet, FAJ

    Low status of long-chain polyunsaturated fatty acids (LCP) and essential fatty acids (EFA) in the fetus is associated with less favorable neonatal neurological condition. A 'relative', rather than 'absolute' EFA deficiency might explain this finding. A relative EFA deficiency may derive from

  16. Physiological traits of Penicillium glabrum strain LCP 08.5568, a filamentous fungus isolated from bottled aromatized mineral water.

    Science.gov (United States)

    Nevarez, L; Vasseur, V; Le Madec, A; Le Bras, M A; Coroller, L; Leguérinel, I; Barbier, G

    2009-04-15

    Penicillium glabrum is a ubiquitous fungus distributed world wide. This fungus is a frequent contaminant in the food manufacturing industry. Environmental factors such as temperature, water activity and pH have a great influence on fungal development. In this study, a strain of P. glabrum referenced to as LCP 08.5568, has been isolated from a bottle of aromatized mineral water. The effects of temperature, a(w) and pH on radial growth rate were assessed on Czapeck Yeast Agar (CYA) medium. Models derived from the cardinal model with inflection [Rosso et al., 1993 An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. J. Theor. Bio. 162, 447-463.] were used to fit the experimental data and determine for each factor, the cardinal parameters (minimum, optimum and maximum). Precise characterisation of the growth conditions for such a fungal contaminant, has an evident interest to understand and to prevent spoilage of food products.

  17. Electric field dependence of crystallinity in poly(vinylidene fluoride)

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, R.G.; Anderson, R.A.; Lagasse, R.R.

    1982-05-03

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  18. Electric Field Dependence of Crystallinity in Poly(Vinylidene Fluoride)

    Science.gov (United States)

    Kepler, R. G.; Anderson, R. A.; Lagasse, R. R.

    1982-05-01

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  19. Crystalline and Crystalline International Disposal Activities

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-21

    This report presents the results of work conducted between September 2014 and July 2015 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program.

  20. Effect of Crystallinity on Electrical Conduction in Polypropylene

    Science.gov (United States)

    Ikezaki, Kazuo; Kaneko, Takanobu; Sakakibara, Toshio

    1981-03-01

    The electrical conduction of 20 μm thick polypropylene films with different crystallinities has been studied at 72°C below 400 kV/cm. The field dependence of the current shows that the conduction mechanism in this polymer is ion hopping. The estimated ionic jump distance strongly depends on the polymer crystallinity, and it decreases from 100 Å to 45 Å as the crystallinity increases from 50.5% to 78%. Preheating of samples seriously affects the electrical conduction in polypropylene, so differences in conductivity, activation energy and jump distance obtained by different authors can be explained partly by differences in the thermal history of the samples used.

  1. Molecular Engineering of Liquid Crystalline Polymers

    Science.gov (United States)

    1992-03-27

    N=C - N- C H 3C/ R H 3C/ \\R H3C / ’\\R + (11) (12) (13) Pauling 112 predicted a rotational energy barrier of 21 kcal/mol which corresponds to about...1991, 15, 153 and D. Philp and J. F. Stoddart, Synlett., 1991, 445; for other representative contributions in this field see: P. L. Anelli, N. Spencer

  2. Mesophase Formation in Discotic Liquid Crystalline Polymers

    NARCIS (Netherlands)

    Kouwer, P.H.J.

    2002-01-01

    Liquid crystals comprise a class of materials in which characteristic properties of crystals and liquids are combined. The materials show partly ordered fluid phases, between the common solid and the liquid phases. The combination of order and a high mobility is applied in the well-known liquid

  3. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  4. Photochromism of 36-Armed Liquid Crystalline Dendrimer

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigated by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of D6 in chloroform (CHCl3) and tetrahydrofuran (THF) solutions are in accordance with the first order kinetics. The photochromism rate constants of D6 are 10-1 s-1, it is 107 times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties.

  5. Monolithic aerogels with nanoporous crystalline phases

    Science.gov (United States)

    Daniel, Christophe; Guerra, Gaetano

    2015-05-01

    High porosity monolithic aerogels with nanoporous crystalline phases can be obtained from syndiotactic polystyrene and poly(2,6-dimethyl-1,4-phenylene)oxide thermoreversible gels by removing the solvent with supercritical CO2. The presence of crystalline nanopores in the aerogels based on these polymers allows a high uptake associated with a high selectivity of volatile organic compounds from vapor phase or aqueous solutions even at very low activities. The sorption and the fast kinetics make these materials particularly suitable as sorption medium to remove traces of pollutants from water and moist air.

  6. Anchoring-Induced Texture & Shear Banding of Nematic Polymers in Shear Cells

    Science.gov (United States)

    2007-10-01

    varying orientation tensor ellipsoid at several locations between the plates. The Doi- Hess kinetic theory is developed to study the dynamics of LCP...profile is evident in one of the snapshots, a phenomenon seen by Sebastian Heidenreich in related studies and in full kinetic flow-nematic simulations of...kinetic phase diagram for nematic polymers, Rheol. Acta., 43 (2004), 17–37. [20] M.G. Forest, Q. Wang and R. Zhou, The flow-phase diagram of Doi- Hess

  7. In-vitro comparison of LC-DCP- and LCP-constructs in the femur of newborn calves – a pilot study

    Directory of Open Access Journals (Sweden)

    Hoerdemann Mona

    2012-08-01

    Full Text Available Abstract Background To compare the biomechanical in-vitro characteristics of limited-contact dynamic compression plate (LC-DCP and locking compression plate (LCP constructs in an osteotomy gap model of femoral fracture in neonatal calves. Pairs of intact femurs from 10 calves that had died for reasons unrelated to the study were tested. A 7-hole LC-DCP with six 4.5 mm cortical screws was used in one femur and a 7-hole LCP with four 5.0 mm locking and two 4.5 mm cortical screws was used in the corresponding femur. The constructs were tested to failure by cyclic compression at a speed of 2 mm/s within six increasing force levels. Results The bone-thread interface was stripped in 21 of 80 cortical screws (26.3% before a pre-set insertion torque of 3 Nm was achieved. Only 3 corresponding intact pairs of constructs could be statistically compared for relative structural stiffness, actuator excursion and width of the osteotomy gap. Relative structural stiffness was significantly greater, actuator excursion and width of the osteotomy gap were significantly smaller in the LCP constructs. While failure occurred by loosening of the screws in the LC-DCP constructs, locking constructs failed by cutting large holes in the soft distal metaphyseal bone. Conclusions An insertion torque sufficient to provide adequate stability in femurs of newborn calves could not be achieved reliably with 4.5 mm cortical screws. Another limiting factor for both constructs was the weak cancellous bone of the distal fracture fragment. LCP constructs were significantly more resistant to compression than LC-DCP constructs.

  8. Comparing the In Vitro Stiffness of Straight-DCP, Wave-DCP, and LCP Bone Plates for Femoral Osteosynthesis.

    Science.gov (United States)

    Mariolani, José Ricardo Lenzi; Belangero, William Dias

    2013-01-01

    The objective of this study was to compare the Locking Compression Plate (LCP) with the more cost-effective straight-dynamic compression plate (DCP) and wave-DCPs by testing in vitro the effects of plate stiffness on different types of diaphyseal femur fractures (A, B, and C, according to AO classification). The bending structural stiffness of each plate was obtained from four-point bending tests according to ASTM F382-99(2008). The plate systems were tested by applying compression/bending in different osteosynthesis simulation models using wooden rods to simulate the fractured bone fragments. Kruskal-Wallis test showed no significant difference in the bending structural stiffness between the three plate models. Rank-transformed two-way ANOVA showed significant influence of plate type, fracture type, and interaction plate versus fracture on the stiffness of the montages. The straight-DCP produced the most stable model for types B and C fractures, which makes its use advantageous for complex nonosteoporotic fractures that require minimizing focal mobility, whereas no difference was found for type A fracture. Our results indicated that DCPs, in straight or wave form, can provide adequate biomechanical properties for fixing diaphyseal femoral fractures in cases where more modern osteosynthesis systems are cost restrictive.

  9. Polymer Blends Containing Liquid Crystalline Component Cholesteryl Palmitate-containing Blends%含液晶成分的掺杂共聚物和胆甾醇基棕榈酸盐(或酯)掺合物

    Institute of Scientific and Technical Information of China (English)

    Maria-Cristina; Popescu; Cornelia; Vasile; Daniela; Filip; Doina; Macocinschi; Gh.; Singurel

    2005-01-01

    @@ Physical blends containing macromolecular compounds and low molecular weight liquid crystals (LCs) have important applications. LCs are used as reinforcements for amorphous polymers or in display devices.

  10. Crystalline and Crystalline International Disposal Activities

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-06

    This report presents the results of work conducted between September 2015 and July 2016 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program. Los Alamos focused on two main activities during this period: Discrete fracture network (DFN) modeling to describe flow and radionuclide transport in complex fracture networks that are typical of crystalline rock environments, and a comprehensive interpretation of three different colloid-facilitated radionuclide transport experiments conducted in a fractured granodiorite at the Grimsel Test Site in Switzerland between 2002 and 2013. Chapter 1 presents the results of the DFN work and is divided into three main sections: (1) we show results of our recent study on the correlation between fracture size and fracture transmissivity (2) we present an analysis and visualization prototype using the concept of a flow topology graph for characterization of discrete fracture networks, and (3) we describe the Crystalline International work in support of the Swedish Task Force. Chapter 2 presents interpretation of the colloidfacilitated radionuclide transport experiments in the crystalline rock at the Grimsel Test Site.

  11. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  12. Controlled synthesis of single-crystalline graphene

    Directory of Open Access Journals (Sweden)

    Wang Xueshen

    2014-02-01

    Full Text Available This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH4 as the precursor. The influence of growth time and the pressure ratio of CH4/H2 on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO2/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

  13. DAE-LCP MIXED METHOD FOR MULTIBODY SYSTEM DYNAMICS WITH FRICTIONAL CONTACTS%多体系统摩擦接触问题的DAE-LCP方法

    Institute of Scientific and Technical Information of China (English)

    富立; 岳凤桐

    2011-01-01

    当多体系统的约束全部是摩擦接触时,其动力学问题可归结为一个常微分方程(ordinary differential equation,ODE)与线性互补问题(linear complementarity problem,LCP)的混合动力学问题.如果除了摩擦接触之外还增加了光滑的双边约束,则需要将ODE-LCP混合动力学模型推广为微分代数方程(differential algebra equation,DAE)与LCP的混合动力学模型.该文采用DAE与LCP混合动力学方法求解不考虑碰撞但同时含有持续摩擦接触及光滑等式约束的多体系统动力学问题.在建立系统动力学模型时,首先将含摩擦的约束从系统中移去得到基本动力学系统.由于基本系统中带有等式约束,所以基本系统的动力学方程为一组DAE.结合基本系统的DAE与约束的互补条件便可以得到DAE-LCP混合动力学模型.数值计算采用基于DAE与LCP的步进(time-stepping)算法,将系统动力学方程及其约束离散化并转化为一个混合LCP进行求解.该算法无需进行滞-滑状态检测,避免了事件检测导致的繁复计算.利用所提方法对典型机构的非光滑非线性特征进行了数值分析,验证了该文方法的正确有效性.%Presently, dynamics of nonsmooth multibody systems is a hot research topic. The usual approach in treating such systems is to derive basic system from the original system by removing the nonsmooth constraints firstly. The Lagrange equations of the second kind of basic system combine with the complementarity condition of the nonsmooth constraints to set up at each discrete moment in time a Linear Complementarity Problem (LCP).This article focuses on the problem of dynamic modeling and numerical simulating of multibody systems with friction contacts. By neglecting the clearance and the effect of impact between rigid bodies and constraints,the state variables in the differential equations are continuous. Due to the set-value mapping characteristic of dry friction forces, the

  14. Alternating Side-Chain Liquid-Crystalline Copolymers with Polar Moieties in the Backbone

    NARCIS (Netherlands)

    Nieuwhof, R.P.

    1999-01-01

    Side-chain liquid-crystalline polymers (SCLCPs) obtained via the alternating copolymeri-zation of maleic anhydride (MA) and mesogenic 1-alkenes are an interesting class of polymers that may show good adhesion towards metal surfaces and form ordered layered structures. If these polymers contain metho

  15. Crystalline boron nitride aerogels

    Science.gov (United States)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  16. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  17. Ligand-Controlled CO2 Activation Mediated by Cationic Titanium Hydride Complexes, [LTiH](+) (L=Cp2 , O).

    Science.gov (United States)

    Tang, Shi-Ya; Rijs, Nicole J; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2015-06-01

    CO2 activation mediated by [LTiH](+) (L=Cp2 , O) is observed in the gas phase at room temperature using electrospray-ionization mass spectrometry, and reaction details are derived from traveling wave ion-mobility mass spectrometry. Wheresas oxygen-atom transfer prevails in the reaction of the oxide complex [OTiH](+) with CO2 , generating [OTi(OH)](+) under the elimination of CO, insertion of CO2 into the metal-hydrogen bond of the cyclopentadienyl complex, [Cp2 TiH](+) , gives rise to the formate complex [Cp2 Ti(O2 CH)](+) . DFT-based methods were employed to understand how the ligand controls the observed variation in reactivity toward CO2 . Insertion of CO2 into the Ti-H bond constitutes the initial step for the reaction of both [Cp2 TiH](+) and [OTiH](+) , thus generating formate complexes as intermediates. In contrast to [Cp2 Ti(O2 CH)](+) which is kinetically stable, facile decarbonylation of [OTi(O2 CH)](+) results in the hydroxo complex [OTi(OH)](+) . The longer lifetime of [Cp2 Ti(O2 CH)](+) allows for secondary reactions with background water, as a result of which, [Cp2 Ti(OH)](+) is formed. Further, computational studies reveal a good linear correlation between the hydride affinity of [LTi](2+) and the barrier for CO2 insertion into various [LTiH](+) complexes. Understanding the intrinsic ligand effects may provide insight into the selective activation of CO2 .

  18. Buckling Instability in Liquid Crystalline Physical Gels

    Science.gov (United States)

    Verduzco, Rafael; Meng, Guangnan; Kornfield, Julia A.; Meyer, Robert B.

    2006-04-01

    In a nematic gel we observe a low-energy buckling deformation arising from soft and semisoft elastic modes. We prepare the self-assembled gel by dissolving a coil side-group liquid-crystalline polymer coil copolymer in a nematic liquid crystal. The gel has long network strands and a precisely tailored structure, making it ideal for studying nematic rubber elasticity. Under polarized optical microscopy we observe a striped texture that forms when gels uniformly aligned at 35 °C are cooled to room temperature. We model the instability using the molecular theory of nematic rubber elasticity, and the theory correctly captures the change in pitch length with sample thickness and polymer concentration. This buckling instability is a clear example of a low-energy deformation that arises in materials where polymer network strains are coupled to the director orientation.

  19. Liquid crystallinity driven highly aligned large graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Eun; Oh, Jung Jae; Yun, Taeyeong [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Sang Ouk, E-mail: sangouk.kim@kaist.ac.kr [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

    2015-04-15

    Graphene is an emerging graphitic carbon materials, consisting of sp{sup 2} hybridized two dimensinal honeycomb structure. It has been widely studied to incorporate graphene with polymer to utilize unique property of graphene and reinforce electrical, mechanical and thermal property of polymer. In composite materials, orientation control of graphene significantly influences the property of composite. Until now, a few method has been developed for orientation control of graphene within polymer matrix. Here, we demonstrate facile fabrication of high aligned large graphene oxide (LGO) composites in polydimethylsiloxane (PDMS) matrix exploiting liquid crystallinity. Liquid crystalline aqueous dispersion of LGO is parallel oriented within flat confinement geometry. Freeze-drying of the aligned LGO dispersion and subsequent infiltration with PDMS produce highly aligned LGO/PDMS composites. Owing to the large shape anisotropy of LGO, liquid crystalline alignment occurred at low concentration of 2 mg/ml in aqueous dispersion, which leads to the 0.2 wt% LGO loaded composites. - Graphical abstract: Liquid crystalline LGO aqueous dispersions are spontaneous parallel aligned between geometric confinement for highly aligned LGO/polymer composite fabrication. - Highlights: • A simple fabrication method for highly aligned LGO/PDMS composites is proposed. • LGO aqueous dispersion shows nematic liquid crystalline phase at 0.8 mg/ml. • In nematic phase, LGO flakes are highly aligned by geometric confinement. • Infiltration of PDMS into freeze-dried LGO allows highly aligned LGO/PDMS composites.

  20. The Performance Analysis of the Supramolecular Liquid-Crystalline Polymers Based on Weak Intermolecular Force%弱分子间力超分子液晶性能的分析

    Institute of Scientific and Technical Information of China (English)

    康永

    2012-01-01

    Supramolecular liquid crystalline is a various supramolecular liquid crystalline composite system, and it is constructed by the weaker intermolecular interaction of the hydrogen bonding, ion interac- tion, charge transfer interaction, hydrophobic interaction and Vander Waal's force and so on. It possesses dynamic functionality of the transmissibility of the quality or charge, the information stored func- tions, molecular sensing, environmentally friendly character and low energy consumption processability. The factors affecting the performance of supramolecular liquid crystalline are analyzed and researched, and the classification of the supramolecular liquid crystalline is introduced.%超分子液晶是利用氢键、离子相互作用、电荷转移相互作用、疏水相互作用及范德华力等弱分子间相互作用构筑的多种超分子液晶复合体系。超分子液晶复合体系具有质量或电荷传输性、传递性、信息储存功能、分子传感等动态功能性、环境友好性及低能耗加工性等特点。对超分子液晶的性能影响因素进行了深入分析与研究,并对超分子液晶分类进行了介绍。

  1. Structure-property relations in polymers: Spectroscopy and performance

    Energy Technology Data Exchange (ETDEWEB)

    Urban, M.W.; Craver, C.D. [eds.

    1993-12-31

    The `Structure-Property Relations in Polymers` volume was developed from a symposium sponsored by the Division of Polymeric Materials: Science and Engineering at the 201st National Meeting of the American Chemical Society in April, 1991. Topics discussed are related to: Fundamental Concepts in Spectroscopy Polymers; Crystalline Polymers and Copolymers; Surfaces and Interfaces of Polymers; Spectroscopic Approaches to Polymers in Solutions and Polymer Networks; Spectroscopy and Thermally Induced process in Polymers; and Polymer Analysis and Surface Modification. The volume details new spectroscopic methods of analysis including Fourier Transform Infrared, Raman, Vibrational Spectroscopy, and Fluorescence Methods. Several papers cover the effects of radiation on polymers.

  2. Nanoimprinted polymer solar cell.

    Science.gov (United States)

    Yang, Yi; Mielczarek, Kamil; Aryal, Mukti; Zakhidov, Anvar; Hu, Walter

    2012-04-24

    Among the various organic photovoltaic devices, the conjugated polymer/fullerene approach has drawn the most research interest. The performance of these types of solar cells is greatly determined by the nanoscale morphology of the two components (donor/acceptor) and the molecular orientation/crystallinity in the photoactive layer. A vertically bicontinuous and interdigitized heterojunction between donor and acceptor has been regarded as one of the ideal structures to enable both efficient charge separation and transport. Synergistic control of polymer orientation in the nanostructured heterojunction is also critical to improve the performance of polymer solar cells. Nanoimprint lithography has emerged as a new approach to simultaneously control both the heterojunction morphology and polymer chains in organic photovoltaics. Currently, in the area of nanoimprinted polymer solar cells, much progress has been achieved in the fabrication of nanostructured morphology, control of molecular orientation/crystallinity, deposition of acceptor materials, patterned electrodes, understanding of structure-property correlations, and device performance. This review article summarizes the recent studies on nanoimprinted polymer solar cells and discusses the outstanding challenges and opportunities for future work.

  3. The human crystallin gene families

    Directory of Open Access Journals (Sweden)

    Wistow Graeme

    2012-12-01

    Full Text Available Abstract Crystallins are the abundant, long-lived proteins of the eye lens. The major human crystallins belong to two different superfamilies: the small heat-shock proteins (α-crystallins and the βγ-crystallins. During evolution, other proteins have sometimes been recruited as crystallins to modify the properties of the lens. In the developing human lens, the enzyme betaine-homocysteine methyltransferase serves such a role. Evolutionary modification has also resulted in loss of expression of some human crystallin genes or of specific splice forms. Crystallin organization is essential for lens transparency and mutations; even minor changes to surface residues can cause cataract and loss of vision.

  4. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2010-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattices, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. This book is divided into three parts. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. In the third part, the multi-electron system is discussed theoretically, as a quantum-mechanical example, for the superconducting state in metallic crystals. Throughout the book, the role played by the lattice is emphasized and examined in-depth. Thermodynamics of Crystalline States is an introductory treatise and textbook on meso...

  5. The influence of polymerization rate on conductivity and crystallinity of electropolymerized polypyrrole

    DEFF Research Database (Denmark)

    Dyreklev, P.; Granström, M.; Inganäs, O.

    1996-01-01

    conductivity and increased crystallinity. The conductivity is also less temperature activated compared to that of the polymer grown at higher rate. X-ray diffractograms are compared to simulated diffraction data and the results are discussed in terms of increased order in the material. This may result from......We report studies on electronic conductivity and crystallinity in electropolymerized polypyrrole. Different growth rates during electropolymerization strongly influence and determine structural and electronic properties. Polymer films grown using low current density show higher electronic...

  6. Photoorientation of a liquid crystalline polyester with azobenzene side groups

    DEFF Research Database (Denmark)

    Zebger, I; Rutloh, M; Hoffmann, U

    2002-01-01

    . This model polymer is characterized by liquid crystallinity (g 24 S-X 26 S-A 34 n 47 i) and a strong aggregation tendency. The photoorientation is cooperative, i.e., the orientation of the photochromic side group induces the alignment of the ester unit (which is a part of the main-chain) and both methylene...

  7. Shear effects on crystalline structures of poly(L-lactide)

    DEFF Research Database (Denmark)

    Xiao, Peitao; Li, Hongfei; Huang, Shaoyong;

    2013-01-01

    The shearing effects of sheared polymer melts on their finally formed crystalline structures of poly(L-lactide) (PLLA) were investigated by means of small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD). The results of WAXD prove that shear has no effects on the crystal...

  8. Coilable Crystalline Fiber (CCF) Lasers and their Scalability

    Science.gov (United States)

    2014-03-01

    cladding is a low-index polymer coating ) the large cladding NA and relatively large cladding diameter (versus core) greatly facilitate pump power...particularly if double- clad , would improve all these properties, greatly facilitating power scaling. Yet, progress in fabricating all-crystalline...using current bonding techniques, with geometry similar to conventional double- clad fibers. We measured refractive indices to determine the

  9. 基于弱分子间力超分子液晶性能影响因素分析%THE PERFORMANCE INFLUENCE FACTORS RESEARCH OF THE SUPRAMOLECULAR LIQUID-CRYSTALLINE POLYMERS BASED ON WEAKER INTERMOLECULAR FORCE

    Institute of Scientific and Technical Information of China (English)

    赵驰峰

    2012-01-01

    Supramolecular liquid crystalline was a various supramolecular liquid crystallines composite system, and it was constructed by the weaker intermolecular interaction of the hydrogen bondind, ion interaction, charge transfer interaction, hydrophobic interaction and vander waals force and so on. It was possesed dynamic reversibility, and depend on changing the structure to response the stimulation of the external environment(pressure, temperature, magnetic field, electric field, pH, light perception as well as chemical reaction, etc.) by means of association and disassociation of the hydrogen bond and the charge transfer. Furthermore, it was possesed dynamic functionality of the transmissibility of the quality or charge, the information stored functions, molecular sensing, environmental friendly character and low energy consumption processability, so it was the main tendency of the material scientific systems in the future. It was analysesed and researched the performance influence factors of supramolecular liquid crystalline composite system, and introduced the classification of the supramolecular liquid crystalline in this paper.%超分子液晶是利用氢键、离子相互作用、电荷转移相互作用、疏水相互作用及范德华力等弱分子间相互作用构筑的多种超分子液晶复合体系.这种弱分子间力具有动态可逆性,对外部环境(压力、温度、磁场、电场、pH值、光感、化学反应等)具有通过氢键的缔合与解缔合以及电荷转移来改变其结构的独特的响应刺激的功能特性.另外,利用弱分子间力构筑的超分子液晶复合体系具有质量或电荷传输性、传递性、信息储存功能、分子传感等动态功能性、环境友好性及低能耗加工性等特点,故该领域将是未来材料科学体系发展的主方向.本文对超分子液晶的性能影响因素进行了深入分析与研究,并对超分子液晶分类进行了介绍.

  10. Polymer semiconductor crystals

    Directory of Open Access Journals (Sweden)

    Jung Ah Lim

    2010-05-01

    Full Text Available One of the long-standing challenges in the field of polymer semiconductors is to figure out how long interpenetrating and entangled polymer chains self-assemble into single crystals from the solution phase or melt. The ability to produce these crystalline solids has fascinated scientists from a broad range of backgrounds including physicists, chemists, and engineers. Scientists are still on the hunt for determining the mechanism of crystallization in these information-rich materials. Understanding the theory and concept of crystallization of polymer semiconductors will undoubtedly transform this area from an art to an area that will host a bandwagon of scientists and engineers. In this article we describe the basic concept of crystallization and highlight some of the advances in polymer crystallization from crystals to nanocrystalline fibers.

  11. Some Remarks on the Degree of Crystallinity Measured on DSC

    Institute of Scientific and Technical Information of China (English)

    邱高; 唐志廉; 黄南薰

    2001-01-01

    A modified mathematical model based on the melting and recrystallization of an initial distribution of melting temperatures predicts the melting behavior of polymer in differential scanning calorimetry ( DSC ), taking into account of changes in heat of fusion with melting temperature of crystal and average heat capacity of sample. It has been used to analytically prove that the crystallinity measured on a DSC diagram could not be equal to the weight percentage of crystalline state in the initial specimen. The deviation of the measured crystallinity, as observed relevant to the melting and recrystallization processes, is caused by the changes of the heat of fusion with the melting temperature of crystals, as well as the difference of heat capacities of liquld and solid state polymer. Furthermore, upper and lower limits of the deviation have been discussed.

  12. Calcium carbonate interaction analysis in polypropylene compounds and their impact on the formation of beta crystalline phase of this polymer; Analise da interacao de diferentes tipos de carbonato de calcio em compositos de polipropileno e suas consequencias na formacao da fase cristalina beta do PP

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The insertion of calcium carbonate (CaCO{sub 3}) in polypropylene compound is a thoroughly known technique widely studied in the academic area and in the industry. Its wide application is due, mainly, to increase mechanical properties with low manufacturing cost. These improvements in this polymer make it more versatile and competitive compared to other expensive polymers. In this study, the incorporation of four types of CaCO3 from the same manufacturer were compared and the focus was on the size of this mineral filler. Furthermore, it was analyzed the interaction of graphitized polypropylene with maleic anhydride (PP-g-MA) in the same samples. All these samples were analyzed by WAXS and SEM. The physical properties of tensile strength and impact were also analyzed. It was observed from this study that the smallest CaCO3 produced with PP-g-MA resulted in better physical properties with the formation of a crystalline phase beta, as originally studied by other authors using other raw materials. (author)

  13. The impact of P(NDI2OD-T2 crystalline domains on the open-circuit voltage of bilayer all-polymer solar cells with an inverted configuration

    Directory of Open Access Journals (Sweden)

    Yu Jin Kim

    2015-12-01

    Full Text Available We fabricated P(NDI2OD-T2/PTB7 bilayer all-polymer solar cells with an inverted configuration, where the annealing temperature was systematically varied. The current density–voltage behavior was investigated and the structural properties of the P(NDI2OD-T2 layers were characterized. Absorption spectroscopy, surface morphology, and crystallite analysis showed that increasing phase segregation of P(NDI2OD-T2 films occurred as the annealing temperature increased. We found that, as the P(NDI2OD-T2 stacking improved, with larger domains, the open-circuit voltage decreased and the saturation dark current density increased. This work provides a guide for the processing of P(NDI2OD-T2 layers to maximize the power conversion efficiency of all-polymer solar cells.

  14. Liquid crystalline dihydroazulene photoswitches

    DEFF Research Database (Denmark)

    Petersen, Anne Ugleholdt; Jevric, Martyn; Mandle, Richard J.

    2015-01-01

    A large selection of photochromic dihydroazulene (DHA) molecules incorporating various substituents at position 2 of the DHA core was prepared and investigated for their ability to form liquid crystalline phases. Incorporation of an octyloxy-substituted biphenyl substituent resulted in nematic...

  15. Neural signal recording using microelectrode arrays fabricated on liquid crystal polymer material

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choong Jae; Oh, Seung Jae; Song, Jong Keun; Kim, Sung June

    2004-01-05

    Microelectrode arrays have been developed for simultaneous multi-channel recordings from nervous systems, typically using silicon substrates. However, it has been known that it is difficult to meet the biocompatibility and durability requirements using silicon and other dielectric materials (SiO{sub 2}, Si{sub 3}N{sub 4}), due to environmental moisture and ions. Additional disadvantage of silicon being the rigid material makes it hard to apply these materials in chronic recording situations. Liquid Crystal Polymer (LCP) was recently introduced as a candidate material for electronic packaging purposes. The material acts as efficient barrier against ions and moisture, a desirable feature for a substrate material of microelectrode arrays. In this paper, we report on the neural recording performed using the LCP-based microelectrode arrays. The cell adhesion on the new material was compared very favorably with that using silicon, SiO{sub 2}, or polyimide material. The microelectrode arrays were patterned with Ti (500 Angst)/Au (3500 Angst) on the LCP film and were employed in both stimulation and recording from rat sciatic nerve. The electrical characteristic of the recorded signal was as good as those using other substrate materials, proving this material as an excellent candidate for next generation microelectrode arrays.

  16. Thermophysical Properties of Irradiated Polymers

    Science.gov (United States)

    Briskman, Boris A.

    1983-05-01

    The effect of ionising radiation on the specific heat, thermal conductivity, thermal diffusivity, and density of partially crystalline (polyethylene, polypropylene, polytetrafluoro-ethylene) and of amorphous polymers (polystyrene, poly(methyl methacrylate)) is discussed. Analytical models of the mechanism of heat conduction, and the development of anisotropic thermal conductivity in amorphous polymers, are examined. The influence of ionising radiation on the thermophysical properties of composite materials is analysed. 79 references.

  17. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  18. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  19. Interface Induced Growth and Transformation of Polymer-Conjugated Proto-Crystalline Phases in Aluminosilicate Hybrids: A Multiple-Quantum (23)Na-(23)Na MAS NMR Correlation Spectroscopy Study.

    Science.gov (United States)

    Brus, Jiri; Kobera, Libor; Urbanova, Martina; Doušová, Barbora; Lhotka, Miloslav; Koloušek, David; Kotek, Jiří; Čuba, Pavel; Czernek, Jiri; Dědeček, Jiří

    2016-03-22

    Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix. This secondary epoxide phase not only enhances the mechanical integrity of the resulting hybrids but also introduces additional binding sites accessible for compensating negative charge on the aluminosilicate framework. This way, the polymer network initiates growth and subsequent transformation of protocrystalline short-range ordered zeolite domains that are located at the organic-inorganic interface. By applying an experimental approach based on 2D (23)Na-(23)Na double-quantum (DQ) MAS NMR spectroscopy, we discovered multiple sodium binding sites in these protocrystalline domains, in which immobilized Na(+) ions form pairs or small clusters. It is further demonstrated that these sites, the local geometry of which allows for the pairing of sodium ions, are preferentially occupied by Pb(2+) ions during the ion exchange. The proposed synthesis protocol thus allows for the preparation of a novel type of geopolymer hybrids with polymer-conjugated zeolite phases suitable for capturing and storage of metal cations. The demonstrated (23)Na-(23)Na DQ MAS NMR combined with DFT calculations represents a suitable approach for understanding the role of Na(+) ions in aluminositicate solids and related inorganic-organic hybrids, particularly their specific arrangement and clustering at interfacial areas.

  20. Novel Polymer Architectures for Optical Storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Forcén, Patrica; Oriol, Luis

    2007-01-01

    Azobenzene containing polymers have been shown to have a large potential for high capacity olographic information storage. However, it has been difficult to fabricate thick films of the polymers with good op~ical quality so far. Liquid crystalline block copolymers prepared by Atom Transfer Radica...

  1. In Situ and Ex Situ Syntheses of Magnetic Liquid Crystalline Materials: A Comparison

    Directory of Open Access Journals (Sweden)

    Monique Mauzac

    2012-02-01

    Full Text Available Magnetic hybrid liquid crystalline composites have been obtained either by thermal decomposition of a cobalt precursor in a solution containing a liquid crystal polymer or by dispersing preformed cobalt nanorods in a liquid crystal polymer matrix. The final materials are all mesomorphous and ferromagnetic. Their magnetic characteristics are compared as a function of the synthesis method.

  2. SYNTHESIS OF LIQUID CRYSTALLINE POLYACRYLATES WITH THIOESTER AS BRIDGE-BOND

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weibang; ZHANG Guodong; XU Jiarui; ZENG Hanmin

    1996-01-01

    A new series of acrylates with the same mesogens containing thioester as bridge-bond were synthesized, and the acrylates were characterized by H1 NMR, IR and MS. The polymers were obtained by radical polymerization using AIBN as initiator. The monomers and polymers exhibit thermotropic-enantiotropic liquid crystalline behavior.

  3. Crystalline systems. [Book chapter

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, L.D.

    The use of two double resonance methods, electron-nuclear double resonance (ENDOR) and electron-electron double resonance (ELDOR) in the study of free radicals in solids is reviewed. Included are descriptions of how crystalline-phase ENDOR is used to determine small hyperfine splittings, quadrupoly couplings, and reaction mechanisms or radical formation and how crystalline phase ELDOR is used to determine large hyperfine splittings, to identify radicals with large quadrupole moments and to study spin exchange processes. The complementary role played by the ENDOR and ELDOR spectroscopy in the separation of overlapping EPR spectra, in the study of proton-deuterium exchange, in the study of methyl groups undergoing tunneling rotation, and in the determination of the rates of intermolecular motion are dealt with. 13 figures, 1 table. (DP)

  4. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2013-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium with the surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattice, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. New to this edition is the examination of magnetic crystals, where magnetic symmetry is essential for magnetic phase transitions. The multi-electron system is also discussed  theoretically, as a quantum-mechanical example, for superconductivity in metallic crystals. Throughout the book, the role played by the lattice is emphasized and studied in-depth. Thermod...

  5. Anisotropy and Crystalline Structure in Polyaniline Films

    Science.gov (United States)

    Minto, C. D. G.; Vaughan, A. S.

    1996-03-01

    Films of polyaniline -- camphor sulphonic acid cast from m-cresol exhibit transport properties characteristic of a material stradelling the metal/insulator transition. This improvement in properties over traditional methods of polyaniline production has been suggested as being caused by the macromolecule adopting an expanded coil configuration in this solvent. Such films have been shown to be semi--crystalline and are presumed to be completely isotropic. We present here new results which demonstrate that such films are in fact appreciably aligned. X-ray scattering is utilised to expose the presence of molecular anisotropy within such films, the polymers forming a stacked structure with the molecules preferentially oriented parallel to the plane of the film. Similar measurements confirm that the molecules are randomly oriented within this plane. Such alignment considerably improves the transport properties. Anisotropy and the crystalline structure within these films, those cast from chloroform and those using the isolated enantiomeric counter ion are quantified and discussed. The results demonstrate that improved transport properties have arisen as a result of both polymer--solvent interactions and as a result of improved chain alignment.

  6. Influence of low-density polyethylene on the thermal characteristics and crystallinity of high melting point macro- and micro-crystalline waxes

    Energy Technology Data Exchange (ETDEWEB)

    Zaky, Magdy T., E-mail: magdytadrous@hotmail.com [Petroleum Refining Division, Egyptian Petroleum Research Institute (EPRI), 1-Ahmed El-Zomor Street, Hai Al-Zehour, Nasr City, P.O. Box 11727, Cairo (Egypt); Mohamed, Nermen H. [Petroleum Refining Division, Egyptian Petroleum Research Institute (EPRI), 1-Ahmed El-Zomor Street, Hai Al-Zehour, Nasr City, P.O. Box 11727, Cairo (Egypt)

    2010-02-20

    The influence of low-density polyethylene on the thermal characteristics and the crystallinity of high melting point macro- and micro-crystalline waxes were investigated. The samples were prepared through melt blending using mechanical stirrer. The thermal characteristics of the blended samples were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crystallinity of the samples was obtained using X-ray diffraction analyzer (XRD). The observations are discussed in terms of possible changes when the polymer is mixed with two types of waxes. The wax-polymer miscibility differed with the type of the wax and the amount of polymer mixed into the wax. Also, the crystallinity and congealing point of the waxes differed with the amount of polymer mixed into the wax. Moreover, the resulting data indicate that, blending of polymer with high melting point micro-crystalline wax elevates its melting point to reach the limits of high melting point ceresin waxes which can be used in different industrial applications.

  7. STUDY ON THE BLENDS OF NYLON 66 AND LIQUID CRYSTALLINE POLYESTERS

    Institute of Scientific and Technical Information of China (English)

    Zhang Shufan; Ren Jinghong

    1991-01-01

    Blends of polyamide (Nylon 66 ) with two different kinds of liquid crystalline polyesters were studied in all the composition range. Homogeneous samples were obtained by coprecipitation from 2wt%. solution of blends. The thermal properties, crystallinity and morphology of these blends were studied by using DSC, polarizing microscopy, and scanning electron microscopy. The phase transition and morphology of the blends are markedlyinfluenced by the composition of liquid crystalline polyesters. The mechanical behaviour of PHB/HNA-Nylon 66 blend was improved .although polyamide (Nylon 66)with the liquid crystalline polyesters were incompatible, but a rather strong interaction between the polymers did exist.

  8. Crystallinity dependent thermal degradation in organic solar cell

    Science.gov (United States)

    Lee, Hyunho; Sohn, Jiho; Tyagi, Priyanka; Lee, Changhee

    2017-01-01

    An operating solar cell undergoes solar heating; thus, the degradation study of organic photo-voltaic (OPV) with a thermal stress is required for their practical applications. We present a thermal degradation study on OPVs fabricated with photo-active polymers having different crystalline phase. Light intensity dependent analysis for different thermal stress duration is performed. In crystalline, the degradation majorly occurs due to drop in open-circuit voltage while in amorphous one it is due to drop in short-circuit current. Physical mechanism in both systems is explained and supported by the X-ray diffraction, morphological and optical characterization.

  9. Doped Chiral Polymer Metamaterials

    Science.gov (United States)

    Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Gordon, Keith L. (Inventor); Sauti, Godfrey (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert G. (Inventor)

    2017-01-01

    Some implementations provide a composite material that includes a first material and a second material. In some implementations, the composite material is a metamaterial. The first material includes a chiral polymer (e.g., crystalline chiral helical polymer, poly-.gamma.-benzyl-L-glutamate (PBLG), poly-L-lactic acid (PLA), polypeptide, and/or polyacetylene). The second material is within the chiral polymer. The first material and the second material are configured to provide an effective index of refraction value for the composite material of 1 or less. In some implementations, the effective index of refraction value for the composite material is negative. In some implementations, the effective index of refraction value for the composite material of 1 or less is at least in a wavelength of one of at least a visible spectrum, an infrared spectrum, a microwave spectrum, and/or an ultraviolet spectrum.

  10. Semiconducting polymers: the Third Generation.

    Science.gov (United States)

    Heeger, Alan J

    2010-07-01

    There has been remarkable progress in the science and technology of semiconducting polymers during the past decade. The field has evolved from the early work on polyacetylene (the First Generation material) to a proper focus on soluble and processible polymers and co-polymers. The soluble poly(alkylthiophenes) and the soluble PPVs are perhaps the most important examples of the Second Generation of semiconducting polymers. Third Generation semiconducting polymers have more complex molecular structures with more atoms in the repeat unit. Important examples include the highly ordered and crystalline PDTTT and the ever-growing class of donor-acceptor co-polymers that has emerged in the past few years. Examples of the latter include the bithiophene-acceptor co-polymers pioneered by Konarka and the polycarbazole-acceptor co-polymers pioneered by Leclerc and colleagues. In this tutorial review, I will summarize progress in the basic physics, the materials science, the device science and the device performance with emphasis on the following recent studies of Third Generation semiconducting polymers: stable semiconducting polymers; self-assembly of bulk heterojunction (BHJ) materials by spontaneous phase separation; bulk heterojunction solar cells with internal quantum efficiency approaching 100%; high detectivity photodetectors fabricated from BHJ materials.

  11. Crystalline mesoporous metal oxide

    Institute of Scientific and Technical Information of China (English)

    Wenbo Yue; Wuzong Zhou

    2008-01-01

    Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.

  12. Correlation measurements of light transmittance in polymer dispersed liquid crystals

    Science.gov (United States)

    Maksimyak, P. P.; Nehrych, A. L.

    2015-11-01

    The methods of correlation optics are for the first time applied to study structure of liquid crystal (LC) - polymer (P) composites at various concentrations of LC and P. Their phase correlation function (PCF) was obtained considering LC-P composite as a random phase screen. The amplitude of PCF contains information about number of LC domains and structure of LC director inside of them, while a half-width of this function is connected with a size of these domains. We studied unpowered and powered composite layers with a thickness of 5 μm. As liquid crystal and polymer were used nematic LC E7 from Merck and photopolymer composition NOA65 from Norland. Concentration of polymer φP was varied in a range 10-55 vol. %. In good agreement with previous studies by SEM technique we detected monotone decrease of LC domains with concentration of polymer. With application of electric field, amplitude of PCF behaves differently for the samples with different polymer content. For the samples with φP>35 vol. % (samples having morphology of polymer dispersed LC), this dependence is monotonic. In turn, if φPLC morphology), the amplitude of PCF non-monotonically depends on the applied voltage going through a maximum. The latter fact is explained by transformation of orientational defects of LC phase with the applied voltage.

  13. Preparation and characterization of the crystalline inclusion complexes between cyclodextrins and poly(1,3-dioxolane)

    Institute of Scientific and Technical Information of China (English)

    李景烨; 颜德岳; 陈群

    2002-01-01

    The preparation and characterization of the crystalline inclusion complexes between a polymeric guest, poly(1,3-dioxolane) (PDXL), and small-molecular hosts, cyclodextrins (CDs) are reported. It is observed that the polymer guest can form crystalline inclusion complexes with three kinds of cyclodextrins, which may be attributed to the high oxygen atom density in PDXL chain. The crystalline inclusion complexes were characterized with FTIR , TGA, X-ray diffraction, SEM, 1H NMR and 13C CP/MAS NMR spectroscopes. It was found that the crystalline inclusion complexes have higher temperature stability than the pure CDs. The X-ray powder diffraction patterns of the crystalline inclusion complexes proved that they have columnar structures. 13C CP/MAS NMR spectra of the crystalline inclusion complexes indicate that CDs adopt a more symmetrical conformation in the complexes, while pure CDs assume a less symmetrical conformation in the crystal without a guest inside their cavities. The morphology of the crystal was

  14. Polymer fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Hadermann, A. F.

    1985-04-09

    Soluble polymers are fractionated according to molecular weight by cryogenically comminuting the polymer and introducing the polymer particles, while still in the active state induced by cryogenic grinding, into a liquid having a solvent power selected to produce a coacervate fraction containing high molecular weight polymer species and a dilute polymer solution containing lower molecular weight polymer species. The coacervate may be physically separated from the solution and finds use in the production of antimisting jet fuels and the like.

  15. Biodegradable Polymers

    OpenAIRE

    Isabelle Vroman; Lan Tighzert

    2013-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  16. Morphology of Low Density Foams from Crystalline Gels.

    Science.gov (United States)

    Beaucage, G.; Schaefer, D. W.; Lagasse, R. R.; Aubert, J. A.; Ehrlich, P.; Stein, R. S.; Whaley, P.; Kulkarni, S.

    1996-03-01

    Low-density polymer foams are often derived via supercritical extraction of crystalline gels. The nano-structural basis of these foams and gels, in a wide variety of systems, is distorted lamellae. We present an uncorrelated lamellar model which describes the small-angle scattering over 5 orders of size in these systems. Our approach is based on the unified approach to small-angle scattering and scattering data from 4 instruments. This approach is equally applicable to olefin foams from gelation in supercritical propane (Whaley, Kulkarni, Stein, Ehrlich), polyacrylonitrile foams and gels from DMF/ethylene glycol followed by supercritical extraction in CO2 (Lagasse) and isotactic PS foams and gels from decalin and extracted in supercritical CO2 (Aubert). Distortion of conventional crystalline morphologies can be rationalized in terms of the extent of entanglement of the polymer chains during crystallization and the deformability of lamellar platelets during supercritical drying. Correlations between melt and dilute solution morphologies are given.

  17. Thermotropic liquid crystalline polyesters derived from 2-chloro hydroquinone

    Indian Academy of Sciences (India)

    NAGESH MANURKAR; SAYAJI MORE; KHUDBUDIN MULANI; NITIN GANJAVE; NAYAKU CHAVAN

    2017-09-01

    Synthesis of thermotropic liquid crystalline polyesters derived from bis[4-hydroxy benzoyloxy]- 2-chloro-1,4-benzene (BHBOCB) and aliphatic dicarboxylic acid chlorides by interfacial polycondensation methodology is presented. Synthesised polyesters consist of bis[4-hydroxy benzoyloxy]-2-chloro-1,4-benzeneas a mesogen and aliphatic diacid chloride as flexible spacer. The length of oligomethylene units in the polymer was varied from the trimethylene to the dodecamethylene groups. Synthesized polyesters were characterizedby differential scanning calorimetry and optical microscopy. The transition temperatures and thermodynamic properties were studied for all these polymers. These polyesters exhibited thermotropic liquid crystalline behavior and showed nematic texture except decamethylene spacer. Decamethylene spacer based polyester showed marble texture of smectic C. Mesophase stability of these polyesters was higher than 123◦C (except first heating cycle of PE-1).

  18. Synthesis and characterization of thermotropic liquid crystalline polyimides

    Indian Academy of Sciences (India)

    Sachin Mane; C R Rajan; Surendra Ponrathnam; Nayaku Chavan

    2015-10-01

    Non-symmetrical and linear dyad-based mesogens were synthesised containing imine or ester bridging group. In the present work, due to the absence of branching in diamine-based mesogen, the structure has—rigidity inversely imine/ester bridging groups between two benzene rings imparts—flexible property to the mesogen and consequently rigid–flexible property has been balanced. The synthesised mesogens were characterized by different techniques including nuclear magnetic resonance and Fourier transform infrared spectroscopy. Liquid crystalline polymers (LCPs) were synthesised using pyromellitic dianhydride and 4-[(4-aminobenzylidene)amino]aniline or 4-aminophenyl-4-aminobenzoate. Subsequently, thermotropic liquid crystalline polymers (TLCPs) have also been evaluated to obtain optical microscopy textures at different temperatures which demonstrated interesting and notable changes. It is worth noting that marble-like textures were observed upto 200 ° C.

  19. Crystallinity of Electrospun and Centrifugal Spun Polycaprolactone Fibers: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Eva Kuzelova Kostakova

    2017-01-01

    Full Text Available Crystalline properties of semicrystalline polymers are very important parameters that can influence the application area. The internal structure, like the mentioned crystalline properties, of polymers can be influenced by the production technology itself and by changing technology parameters. The present work is devoted to testing of electrospun and centrifugal spun fibrous and nanofibrous materials and compare them to foils and granules made from the same raw polymer. The test setup reveals the structural differences caused by the production technology. Effects of average molecular weight are also exhibited. The applied biodegradable and biocompatible polymer is polycaprolactone (PCL as it is a widespread material for medical purposes. The crystallinity of PCL has significant effect on rate of degradation that is an important parameter for a biodegradable material and determines the applicability. The results of differential scanning calorimetry (DSC showed that, at the degree of crystallinity, there is a minor difference between the electrospun and centrifugal spun fibrous materials. However, the significant influence of polymer molecular weight was exhibited. The morphology of the fibrous materials, represented by fiber diameter, also did not demonstrate any connection to final measured crystallinity degree of the tested materials.

  20. Polymer chain organization in tensile-stretched poly(ethylene oxide)-based polymer electrolytes

    Science.gov (United States)

    Burba, Christopher M.; Woods, Lauren; Millar, Sarah Y.; Pallie, Jonathan

    2011-01-01

    Polymer chain orientation in tensile-stretched poly(ethylene oxide)-lithium trifluoromethanesulfonate polymer electrolytes are investigated with polarized infrared spectroscopy as a function of the degree of strain and salt composition (ether oxygen atom to lithium ion ratios of 20:1, 15:1, and 10:1). The 1359 and 1352 cm-1 bands are used to probe the crystalline PEO and P(EO)3LiCF3SO3 domains, respectively, allowing a direct comparison of chain orientation for the two phases. Two-dimensional correlation FT-IR spectroscopy indicates that the two crystalline domains align at the same rate as the polymer electrolytes are stretched. Quantitative measurements of polymer chain orientation obtained through dichroic infrared spectroscopy show that chain orientation predominantly occurs between strain values of 150% and 250%, regardless of salt composition investigated. There are few changes in chain orientation for either phase when the films are further elongated to a strain of 300%; however, the PEO domains are slightly more oriented at the high strain values. The spectroscopic data are consistent with stretching-induced melt-recrystallization of the unoriented crystalline domains in the solution-cast polymer films. Stretching the films pulls polymer chains from the crystalline domains, which subsequently recrystallize with the polymer helices parallel to the stretch direction. If lithium ion conduction in crystalline polymer electrolytes is viewed as consisting of two major components (facile intra-chain lithium ion conduction and slow helix-to-helix inter-grain hopping), then alignment of the polymer helices will affect the ion conduction pathways for these materials by reducing the number of inter-grain hops required to migrate through the polymer electrolyte. PMID:22184475

  1. Polymer chain organization in tensile-stretched poly(ethylene oxide)-based polymer electrolytes.

    Science.gov (United States)

    Burba, Christopher M; Woods, Lauren; Millar, Sarah Y; Pallie, Jonathan

    2011-12-15

    Polymer chain orientation in tensile-stretched poly(ethylene oxide)-lithium trifluoromethanesulfonate polymer electrolytes are investigated with polarized infrared spectroscopy as a function of the degree of strain and salt composition (ether oxygen atom to lithium ion ratios of 20:1, 15:1, and 10:1). The 1359 and 1352 cm(-1) bands are used to probe the crystalline PEO and P(EO)(3)LiCF(3)SO(3) domains, respectively, allowing a direct comparison of chain orientation for the two phases. Two-dimensional correlation FT-IR spectroscopy indicates that the two crystalline domains align at the same rate as the polymer electrolytes are stretched. Quantitative measurements of polymer chain orientation obtained through dichroic infrared spectroscopy show that chain orientation predominantly occurs between strain values of 150% and 250%, regardless of salt composition investigated. There are few changes in chain orientation for either phase when the films are further elongated to a strain of 300%; however, the PEO domains are slightly more oriented at the high strain values. The spectroscopic data are consistent with stretching-induced melt-recrystallization of the unoriented crystalline domains in the solution-cast polymer films. Stretching the films pulls polymer chains from the crystalline domains, which subsequently recrystallize with the polymer helices parallel to the stretch direction. If lithium ion conduction in crystalline polymer electrolytes is viewed as consisting of two major components (facile intra-chain lithium ion conduction and slow helix-to-helix inter-grain hopping), then alignment of the polymer helices will affect the ion conduction pathways for these materials by reducing the number of inter-grain hops required to migrate through the polymer electrolyte.

  2. Interference forming of transmission by polymer dispersed liquid crystals

    Science.gov (United States)

    Maksimyak, P. P.; Nehrych, A. L.

    2013-12-01

    The methods of correlation optics are for the first time applied to study structure of liquid crystal (LC) - polymer (P) composites at various concentrations of LC and P. Their phase correlation function (PCF) was obtained considering LC-P composite as a random phase screen. The amplitude of PCF contains information about number of LC domains and structure of LC director inside of them, while a half-width of this function is connected with a size of these domains. We studied unpowered and powered composite layers with a thickness of 5 μm. As liquid crystal and polymer were used nematic LC E7 from Merck and photopolymer composition NOA65 from Norland. Concentration of polymer ϕP was varied in a range 10-55 vol. %. In good agreement with previous studies by SEM technique we detected monotone decrease of LC domains with concentration of polymer. With application of electric field, amplitude of PCF behaves differently for the samples with different polymer content. For the samples with ϕPLC), this dependence is monotonic. In turn, if ϕPLC morphology), the amplitude of PCF non-monotonically depends on the applied voltage going through a maximum. The latter fact is explained by transformation of orientational defects of LC phase with the applied voltage.

  3. Synthesis and properties of liquid crystalline polyurethanes

    Institute of Scientific and Technical Information of China (English)

    Xin Haobo; Zhang Yunfeng; Xing Zheng

    2006-01-01

    1,4-Bis(p-hydroxybenzoate)phenylene was prepared using 1,4-bis(trimethylsiloxy)benzene and p-hydroxybenzoyl chloride as starting materials.A series of novel 1,4-bis(p-hydroxyalkoxybenzoate)phenylene were synthesized by reaction of 1,4-bis(p-hydroxybenzoate)phenylene with 3-bromopropanol and 4-bromobutanol,respectively,The liquid crystal polyurethanes were prepared by 1,4-bis(p-hydroxyalkoxybenzoate)phenylene with MDI (p-methylene diphenylenediisocyanate) and 2,4-TDI(2,4-toluenediisocyanate),respectively.The thermotropic properties,the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by DSC,IR and POM.It showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 144℃ and 260℃.The transition temperature (Tm and Ti) decreased with an increase in the length of the methylene spacer.

  4. Gamma-irradiation effects to posttranslational modification and chaperon function of bovine {alpha}-crystalline

    Energy Technology Data Exchange (ETDEWEB)

    Hiroki, K; Matsumoto, S.; Awakura, M. [Kyoto Univ., Graduate School of Science, Kyoto (Japan); Fujii, N. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst

    2001-01-01

    The formation of D-asparate (D-Asp) in {alpha}A-crystallin of the aged human eye and the cataract crystalline lens has been reported. Crystalline lens keeps the transparency by forming {alpha}-crystallin which consists of a high order association of {alpha}A-and {alpha}B-crystallin. Bovine {alpha}-crystallin for investigating a chaperone function which protects the crystalline lens from getting to opaque or disordered agglutination with heat or light, is irradiated by gamma-ray (Co-60) at 0, 1, 2, 3, and 4 kGy, respectively. The irradiated bovine {alpha}-crystallin are analyzed with electrophoresis, gel permeation chromatograph, and UV absorption spectrometer for checking on the agglutination and the isomerization of macromolecules. Oxidation of methionine residues (Met-1) and isomerization of asparagine residues (Asp-151) in the {alpha}A-crystallin are ascertained in molecular levels with reversed phase liquid chromatography. The Met-1 oxidation and the Asp-151 isomerization depend on gamma-irradiation doses. It is thought that OH radical and H radical in water generated by the irradiation lead to the oxidation and the isomerization. Stereoinversion in the {alpha}-crystallin following to such a chemical change are considered to lead to the agglutination of polymer and the reduction of chaperon function. (M. Suetake)

  5. Métodos no destructivos de estimación del área foliar por tallo en la variedad LCP 85-384 de caña de azúcar Non-destructive methods for estimating leaf area per stalk in LCP 85-384 sugarcane variety

    Directory of Open Access Journals (Sweden)

    Esteban Brito

    2007-12-01

    Full Text Available En este trabajo se ajustan métodos no destructivos para estimar el área foliar por tallo (AFT de caña de azúcar en la variedad LCP 85-384. Se midió durante el ciclo del cañaveral, en 1031 tallos, la altura de tallo al anillo de la hoja +1 (ALT+1 y se contó el número de hojas verdes liguladas por tallo (NHVt, determinando también la superficie foliar individual (AFi de todas las hojas verdes. El área foliar observada por tallo (AFTO resultó de la sumatoria del AFi de las hojas liguladas por tallo. Se evaluaron tres alternativas de estimación del AFT: en el Método 1, x= ALT+1 * NHVt; en el Método 2, x= AFi(hoja+3 * NHVt y en el Método 3, x= AFi(hoja+3* NHVt * ALT+1. Las ecuaciones de regresión se seleccionaron considerando el coeficiente de determinación (R², su significación estadística y la observación gráfica de los valores observados y calculados. Para el Método 1 se eligió la ecuación potencial AFT= 6,791 x 0,811 (R²:0,951; para el Método 2, el modelo lineal AFT= 0,930 x (R²: 0,955 y para el Método 3, la ecuación AFT= 2,267 x0,522 (R²: 0,958. Conociendo el número de hojas verdes liguladas por tallo y su altura al anillo de la hoja +1, y/o midiendo el área individual de la hoja+3, se puede estimar, durante todo el ciclo del cultivo, el área foliar por tallo de la variedad LCP 85-384, de manera no destructiva, rápida y precisa.Non-destructive methods for estimating leaf area per stalk (AFT in LCP 85-384 sugarcane variety were adjusted. During crop cycle, 1031 stalks were studied in terms of height with respect of leaf +1 dewlap (ALT+1 and number of green ligulated leaves (NHVt, and individual foliar surface (AFi of all green leaves per stalk was determined. The observed leaf area per stalk (AFTO turned out to be the sum of AFi values of all green ligulated leaves per stalk. Three alternatives for estimating AFT were evaluated: in Method 1, x= ALT+1 * NHVt; in Method 2, x= AFi(leaf +3 * NHVt and in Method 3, x

  6. Crystalline Bioceramic Materials

    Directory of Open Access Journals (Sweden)

    de Aza, P. N.

    2005-06-01

    Full Text Available A strong interest in the use of ceramics for biomedical engineering applications developed in the late 1960´s. Used initially as alternatives to metallic materials in order to increase the biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics; bioactive or surface reactive bioceramics and bioresorbable ceramics. This review will only refer to bioceramics “sensus stricto”, it is to say, those ceramic materials constituted for nonmetallic inorganic compounds, crystallines and consolidated by thermal treatments of powders to high temperatures. Leaving bioglasses, glass-ceramics and biocements apart, since, although all of them are obtained by thermal treatments to high temperatures, the first are amorphous, the second are obtained by desvitrification of a glass and in them vitreous phase normally prevails on the crystalline phases and the third are consolidated by means of a hydraulic or chemical reaction to room temperature. A review of the composition, physiochemical properties and biological behaviour of the principal types of crystalline bioceramics is given, based on the literature data and on the own experience of the authors.

    A finales de los años sesenta se despertó un gran interés por el uso de los materiales cerámicos para aplicaciones biomédicas. Inicialmente utilizados como una alternativa a los materiales metálicos, con el propósito de incrementar la biocompatibilidad de los implantes, las biocerámicas se han convertido en una clase diversa de biomateriales, incluyendo actualmente tres tipos: cerámicas cuasi inertes; cerámicas bioactivas o reactivas superficialmente y cerámicas reabsorbibles o biodegradables. En la presente revisión se hace referencia a las biocerámicas en sentido estricto, es decir, a aquellos materiales constitutitos por compuestos inorgánicos no metálicos, cristalinos y consolidados

  7. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  8. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  9. Enhancing the piezoelectric properties of flexible hybrid AlN materials using semi-crystalline parylene

    Science.gov (United States)

    Jackson, Nathan; Mathewson, Alan

    2017-04-01

    Flexible piezoelectric materials are desired for numerous applications including biomedical, wearable, and flexible electronics. However, most flexible piezoelectric materials are not compatible with CMOS fabrication technology, which is desired for most MEMS applications. This paper reports on the development of a hybrid flexible piezoelectric material consisting of aluminium nitride (AlN) and a semi-crystalline polymer substrate. Various types of semi-crystalline parylene and polyimide materials were investigated as the polymer substrate. The crystallinity and surfaces of the polymer substrates were modified by micro-roughening and annealing in order to determine the effects on the AlN quality. The AlN crystallinity and piezoelectric properties decreased when the polymer surfaces were treated with O2 plasma. However, increasing the crystallinity of the parylene substrate prior to deposition of AlN caused enhanced c-axis (002) AlN crystallinity and piezoelectric response of the AlN. Piezoelectric properties of 200 °C annealed parylene-N substrate resulted in an AlN d 33 value of 4.87 pm V-1 compared to 2.17 pm V-1 for AlN on polyimide and 4.0 pm V-1 for unannealed AlN/parylene-N. The electrical response measurements to an applied force demonstrated that the parylene/AlN hybrid material had higher V pp (0.918 V) than commercial flexible piezoelectric material (PVDF) (V pp 0.36 V). The results in this paper demonstrate that the piezoelectric properties of a flexible AlN hybrid material can be enhanced by increasing the crystallinity of the polymer substrate, and the enhanced properties can function better than previous flexible piezoelectrics.

  10. Homogeneous crystal nucleation in polymers.

    Science.gov (United States)

    Schick, Christoph; Androsch, R; Schmelzer, Juern W P

    2017-07-14

    The pathway of crystal nucleation significantly influences the structure and properties of semi-crystalline polymers. Crystal nucleation is normally heterogeneous at low supercooling, and homogeneous at high supercooling, of the polymer melt. Homogeneous nucleation in bulk polymers has been, so far, hardly accessible experimentally, and was even doubted to occur at all. This topical review summarizes experimental findings on homogeneous crystal nucleation in polymers. Recently developed fast scanning calorimetry, with cooling and heating rates up to 106 K s-1, allows for detailed investigations of nucleation near and even below the glass transition temperature, including analysis of nuclei stability. As for other materials, the maximum homogeneous nucleation rate for polymers is located close to the glass transition temperature. In the experiments discussed here, it is shown that polymer nucleation is homogeneous at such temperatures. Homogeneous nucleation in polymers is discussed in the framework of classical nucleation theory. The majority of our observations are consistent with the theory. The discrepancies may guide further research, particularly experiments to progress theoretical development. Progress in the understanding of homogeneous nucleation is much needed, since most of the modelling approaches dealing with polymer crystallization exclusively consider homogeneous nucleation. This is also the basis for advancing theoretical approaches to the much more complex phenomena governing heterogeneous nucleation. © 2017 IOP Publishing Ltd.

  11. STRUCTURE OF CRYSTALLINE DOMAINS IN SEMICRYSTALLINE BLOCK COPOLYMER THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Guo-dong Liang; Jun-ting Xu; Zhi-qiang Fan

    2006-01-01

    Thin film morphology of a symmetric semicrystalline oxyethylene/oxybutylene diblock copolymer (E76B38) on silicon was investigated by tapping mode atomic force microscopy (AFM). It is found that the nascent thin film is composed of multiple polymer layers having mixed thicknesses of L ≈ L0 and L ≈ L0/2 (L0 is the long period of the block copolymer in bulk) besides the first layer near the substrate. This shows that the crystalline domain in the block copolymer consists of double poly(oxyethylene) layers. Annealing leads to disappearance of the polymer layers with thickness L ≈ L0/2, indicating that such polymer layers are metastable.

  12. Genetics Home Reference: Bietti crystalline dystrophy

    Science.gov (United States)

    ... Understand Genetics Home Health Conditions Bietti crystalline dystrophy Bietti crystalline dystrophy Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description Bietti crystalline dystrophy is a disorder in which numerous ...

  13. How do polymers degrade?

    Science.gov (United States)

    Lyu, Suping

    2011-03-01

    Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

  14. Terahertz Spectroscopy of Crystalline and Non-Crystalline Solids

    DEFF Research Database (Denmark)

    Parrott, Edward P. J.; Fischer, Bernd M.; Gladden, Lynn F.

    2013-01-01

    Terahertz spectroscopy of crystalline and non-crystalline solids is probably one of the most active research fields within the terahertz community. Many potential applications, amongst which spectral recognition is probably one of the most prominent, have significantly stimulated the development...... selected examples, the potential the technique holds for various different applications. A particular focus will be given to data analysis and, in particular, how we may account for effects resulting from non-ideal sample preparation....

  15. CLASSIFICATION OF BIODEGRADABLE POLYMERS

    Directory of Open Access Journals (Sweden)

    I. I. Karpunin

    2015-01-01

    Full Text Available The executed investigations have made it possible to ascertain that a morphological structure of starch granules mainly determine technological peculiarities of starch isolation from raw material, its modification and its later use. Morphological structure of starch granules primarily depends on type of plant starch-containing raw material which has been used for its isolation. Class of raw material exerts a strong impact on the shape and size of the granules. Linear “light” amylose chains and “heavy” amylopectin branch chains form a starch granule ultrastructure. X-ray research has proved that starch granules are characterized by presence of interlacing amorphous and crystalline regions. In this case polymer orientation using stretching of the obtained end product influences on its physical and mechanical  indices which are increasing due to polymer orientation. For the purpose of packaging orientation of polymer films can solve such important problems as significant improvement of operational properties, creation of  thermosetting film materials, improvement of qualitative indices of the recycled film.Results of the conducted research have proved the fact that it is necessary to make changes in technology in order to increase biological degradability of the recycled packaging made from polymers and improve physical and mechanical indices. In this regard film production technology presupposes usage of such substances as stark and others which are characterized by rather large presence of branch chains of molecules and interlacing amorphous and crystalline regions. Such approach makes it possible to obtain after-use package which is strong and quickly degradable by micro-organisms.

  16. A quantitative correlation between the mobility and crystallinity of photo-cross-linkable P3HT

    KAUST Repository

    Woo, Claire

    2012-04-10

    The performance of polymer field effect transistors (FETs) can vary by orders of magnitude by applying different processing conditions. Although it is generally believed that a higher degree of crystallinity results in a higher mobility, the correlation is not straightforward. In addition, the effect of cross-linking on polymer thin film microstructural order is relatively unknown. This study investigates the effect of thermal annealing and UV-initiated photo-cross-linking on the FET performance and microstructural order of a photo-cross-linkable P3HT derivative. Our results demonstrate that while cross-linking did not disrupt the overall crystallinity of the polymer thin film, the photo-cross-linking process likely induced doping in the semiconductor layer, leading to the absence of saturation behavior in the FET. Annealing after cross-linking slightly improved the FET performance but only minimally affected the microstructural order of the polymer film since the 3D morphology had been "locked in" during the first cross-linking step. Importantly, annealing and cross-linking simultaneously was a successful method to preserve polymer crystallinity while also achieving effective cross-linking. Using newly developed quantitative X-ray analysis techniques, our study established a quantitative correlation between FET charge mobility and thin film crystallinity. © 2012 American Chemical Society.

  17. Effects of Polybenzoxazine on Shape Memory Properties of Polyurethanes with Amorphous and Crystalline Soft Segments

    Directory of Open Access Journals (Sweden)

    Senlong Gu

    2014-04-01

    Full Text Available This paper evaluates the role of minor component polybenzoxazine (PB on shape-memory properties of polyurethanes (PU with glassy and crystalline soft segments. The polymer compounds were prepared in two steps. In the first step, benzoxazine, polyurethane pre-polymer, and chain extender butanediol (BD were mixed into a solution followed by chain-extension of the pre-polymer with BD. In the second step, benzoxazine was polymerized at 180 °C for 3 h to obtain shape memory polymer compounds. The atomic force microscopy images revealed that the PB-phase formed uniform dispersions in PU. The presence of PB-phase induced shape-memory behavior in non-shape memory PU with amorphous soft segment and significantly improved the values of shape fixity, recovery ratio, and recovery stress in shape memory polyurethane with crystalline soft segment.

  18. Amorphization of Crystalline Water Ice

    CERN Document Server

    Zheng, Weijun; Kaiser, Ralf I

    2008-01-01

    We conducted a systematic experimental study to investigate the amorphization of crystalline ice by irradiation in the 10-50 K temperature range with 5 keV electrons at a dose of ~140 eV per molecule. We found that crystalline water ice can be converted partially to amorphous ice by electron irradiation. Our experiments showed that some of the 1.65-micrometer band survived the irradiation, to a degree that depends on the temperature, demonstrating that there is a balance between thermal recrystallization and irradiation-induced amorphization, with thermal recrystallizaton dominant at higher temperatures. At 50 K, recrystallization due to thermal effects is strong, and most of the crystalline ice survived. Temperatures of most known objects in the solar system, including Jovian satellites, Saturnian satellites, and Kuiper belt objects, are equal to or above 50 K, this might explain why water ice detected on those objects is mostly crystalline.

  19. Liquid-crystalline lanthanide complexes

    OpenAIRE

    Binnemans, Koen

    1999-01-01

    The paper describes the recent developments in the field of liquid-crystalline lanthanide complexes. The role of trivalent lanthanide ions as the central metal ion in metallomesogens is considered. An outlook for the future is given.

  20. Diffusion in porous crystalline materials

    NARCIS (Netherlands)

    Krishna, R.

    2012-01-01

    The design and development of many separation and catalytic process technologies require a proper quantitative description of diffusion of mixtures of guest molecules within porous crystalline materials. This tutorial review presents a unified, phenomenological description of diffusion inside meso-

  1. Cyclic polymers from alkynes

    Science.gov (United States)

    Roland, Christopher D.; Li, Hong; Abboud, Khalil A.; Wagener, Kenneth B.; Veige, Adam S.

    2016-08-01

    Cyclic polymers have dramatically different physical properties compared with those of their equivalent linear counterparts. However, the exploration of cyclic polymers is limited because of the inherent challenges associated with their synthesis. Conjugated linear polyacetylenes are important materials for electrical conductivity, paramagnetic susceptibility, optical nonlinearity, photoconductivity, gas permeability, liquid crystallinity and chain helicity. However, their cyclic analogues are unknown, and therefore the ability to examine how a cyclic topology influences their properties is currently not possible. We have solved this challenge and now report a tungsten catalyst supported by a tetraanionic pincer ligand that can rapidly polymerize alkynes to form conjugated macrocycles in high yield. The catalyst works by tethering the ends of the polymer to the metal centre to overcome the inherent entropic penalty of cyclization. Gel-permeation chromatography, dynamic and static light scattering, viscometry and chemical tests are all consistent with theoretical predictions and provide unambiguous confirmation of a cyclic topology. Access to a wide variety of new cyclic polymers is now possible by simply choosing the appropriate alkyne monomer.

  2. A CLINICAL STUDY OF PROXIMAL FEMUR LOCKING COMPRESSION PLATE (LCP - PF IN THE MANAGEMENT OF COMMUNITED INTERTROCHANTERIC AND SUBTROCHANTERIC FRACTURES OF THE FEMUR

    Directory of Open Access Journals (Sweden)

    Hari Babu

    2015-10-01

    Full Text Available Fractures of proximal femur and hip are relatively common injuries in elderly individuals . The incidence of peritrochanteric and intertrochanteric fracture is also increasing among young population, who sustain high energy trauma Rigid Internal fixation and early mobilization has been the standard method of treatment. A combination of orthopaedic surgery and early postoperative physiotherapy and ambulation is the best approach. The overall goal in the treatment of hip fractures is to return the patient to pre - morbid level of function. AIMS & OBJECTIVE : To analyse the anatomical and f unctional outcome of the treatment with LCP - Proximal femur. METHODOLOGY : The present study consists of 12 adult patients of peritrochanteric factures of femur satisfying the inclusion criteria , treated with Proximal Femoral Locking Compression Plate at S. V. R. R . Govt . General Hospital, Tirupati during the period of nov 2013 to Oct 2015. INCLUSION CRITERIA : Age >18years , comminuted trochanteric and sub trochanteric fractures , Signed written informed consent . EXCLUSION CRITERIA: Inter trochanteric fractures involving piriformis fossa , Compound fractures . Pathological fractures . Any displacement of a femoral neck fracture . A ssociated malignancy. RESULTS : Average age incidence in the present study was 62.7 years. , Predominantly males (75% were affected. , Most cases occurred after a fall 10 (50% cases which was statistically significant , Right side involvement was more common. , Average post - operative stay was 13.5 days. , Out of the 12 cases, evaluated using Salvati - Wilson scoring : 3 cases (25% had good, 8 cases (66.67% fair, 1 case (8.33% had poor score , Average weight bearing time was14.5 weeks , Average union rate was 19.45 weeks.

  3. The effect of a cholesterol liquid crystalline structure on osteoblast cell behavior.

    Science.gov (United States)

    Xu, Jian-Ping; Ji, Jian; Shen, Jia-Cong

    2009-04-01

    To investigate the effect of a liquid crystalline structure on cell behavior, polymethylsiloxane-graft-(10-cholesteryloxydecanol) was specially designed to get a thermotropic liquid crystalline polymer. Results of Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy and gel permeation chromatography (GPC) indicated that cholesterol was successfully covalently grafted onto polymethylhydrosiloxane via decamethylene 'flexible spacer'. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) investigations revealed that the copolymer with 44.9% mesogenic unit showed obvious thermotropic liquid crystalline transition at about 124.9 degrees C. Polymer films were prepared by spin coating on clean glass plates from 5 mg ml(-1) toluene solutions of the copolymers. The POM investigation indicated that while the unannealed films (SC15, SC45) showed no liquid crystalline structure, the films which were annealed in vacuo at 140 degrees C for 9 h and then quenched to room temperature (SC15C, SC45C) formed discrete island-like liquid crystalline and continuous liquid crystalline structures, respectively. Osteoblast cells (MC3T3) were chosen to test the cell behavior of annealed and unannealed films. In comparison to unannealed films, the annealed films with a cholesterol liquid crystalline structure could promote osteoblast cell attachment and growth significantly.

  4. Spontaneous crystallinity loss of drugs in the disordered regions of poly(ethylene oxide) in the presence of water.

    Science.gov (United States)

    Marsac, Patrick J; Romary, Daniel P; Shamblin, Sheri L; Baird, Jared A; Taylor, Lynne S

    2008-08-01

    The physical stability of active pharmaceutical ingredients (APIs) formulated in the crystalline state may be compromised in the presence of excipients. In the present study, it is shown that at high relative humidity, several model crystalline drugs compacted into a matrix of poly(ethylene oxide) (PEO) may dissolve into the disordered regions of the polymer. The purpose of this project is to identify both the physicochemical properties of the API and the polymer which may lead to such a transformation and the mechanism of transformation. Crystalline drugs and PEO were physically mixed, compressed into tablets, and stored in a dessicator at 94% RH. The physical state of the drug and the polymer were determined using Raman spectroscopy and X-ray powder diffraction. The solubility of each drug in PEG 400 was measured by ultraviolet spectroscopy, the thermal properties of each compound were measured using differential scanning calorimetry, and the amount of water sorbed into these systems from the vapor phase was determined by gravimetric analysis. A spontaneous loss of crystallinity was observed for many of the model drugs when stored at high relative humidity and in the presence of PEO. In the absence of PEO, no changes in the crystalline material were observed. However, the structure of PEO was dramatically altered when exposed to high relative humidity. Specifically, it was found that PEO undergoes a very slow deliquescence increasing the disordered fraction of the polymer which facilitates the "dissolution" of the crystalline drug into these disordered regions. The degree of transformation, estimated from Raman spectroscopy, was found to qualitatively correlate with the aqueous solubility of the compounds. It can be concluded that for the systems studied here, the phase stability of the polymer was compromised at high relative humidity and the polymer underwent deliquescence. The equilibrium phase of several of the crystalline drugs studied here was then altered

  5. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    1995-01-01

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer w

  6. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    1995-01-01

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer w

  7. Ex-ante environmental and economic evaluation of polymer photovoltaics

    NARCIS (Netherlands)

    Roes, A.L.|info:eu-repo/dai/nl/303022388; Alsema, E.A.|info:eu-repo/dai/nl/073416258; Blok, K.|info:eu-repo/dai/nl/07170275X; Patel, M.K.|info:eu-repo/dai/nl/18988097X

    2009-01-01

    The use of polymer materials for photovoltaic applications is expected to have several advantages over current crystalline silicon technology. In this paper, we perform an environmental and economic assessment of polymer-based thin film modules with a glass substrate and modules with a flexible

  8. Ex-ante environmental and economic evaluation of polymer photovoltaics

    NARCIS (Netherlands)

    Roes, A.L.; Alsema, E.A.; Blok, K.; Patel, M.K.

    2009-01-01

    The use of polymer materials for photovoltaic applications is expected to have several advantages over current crystalline silicon technology. In this paper, we perform an environmental and economic assessment of polymer-based thin film modules with a glass substrate and modules with a flexible subs

  9. Ex-ante environmental and economic evaluation of polymer photovoltaics

    NARCIS (Netherlands)

    Roes, A.L.|info:eu-repo/dai/nl/303022388; Alsema, E.A.|info:eu-repo/dai/nl/073416258; Blok, K.|info:eu-repo/dai/nl/07170275X; Patel, M.K.|info:eu-repo/dai/nl/18988097X

    2009-01-01

    The use of polymer materials for photovoltaic applications is expected to have several advantages over current crystalline silicon technology. In this paper, we perform an environmental and economic assessment of polymer-based thin film modules with a glass substrate and modules with a flexible subs

  10. Pendant triazole ring assisted mesogen containing side chain liquid crystalline polymethacrylates: Synthesis and characterization

    Indian Academy of Sciences (India)

    T Palani; C Saravanan; P Kannan

    2011-01-01

    Two series of click chemistry assisted alkoxymethyl-1H-[1,2,3]-triazol-1-yl containing sidechain liquid-crystalline polymethacrylates were synthesized by free radical polymerization technique. Mesogen was linked to backbone through various spacer units. Monomers and polymers were characterized by FT-IR, 1H and 13C-NMR spectral techniques. Thermal stability of polymers was confirmed by thermogravimetric analysis. Mesomorphic property and phase transition temperature of polymers were analysed by differential scanning calorimetry and polarized optical microscopy. Phase transition temperature and mesomorphic property of polymers with respect to insertion of polar alkoxy group on terminal triazole ring and spacer length between backbone and mesogen were investigated. Polymers exhibited grainy like textures under polarized optical microscopy. Spacer length between mesogen and backbone alters phase transition temperature of the polymers.

  11. Polymer Brushes

    NARCIS (Netherlands)

    Vos, de W.M.; Kleijn, J.M.; Keizer, de A.; Cosgrove, T.; Cohen Stuart, M.A.

    2010-01-01

    A polymer brush can be defined as a dense array of polymers end-attached to an interface that stretch out into the surrounding medium. Polymer brushes have been investigated for the past 30 years and have shown to be an extremely useful tool to control interfacial properties. This review is intended

  12. Stability of Equilibria of Nematic Liquid Crystalline Polymers

    Science.gov (United States)

    2011-01-01

    into bullet-proof vests and airbags . The theoretical studies of liquid crystals traced back more than 60 years ago. In 1949 Onsager [29] developed a...distribution: The free energy of the orientational distribution ρ(m) is G([ρ]) = ∫ S [ log ρ(m) + 1 2 U(m, [ρ]) ] ρ(m)dm. (16) Recall that for any ρ(m), by...equation (12), it satisfies f(r(b)) = 1/b. Substituting this into (29) yields H11 = 1− b 3 2 ( 〈m43〉 − 〈m 2 3〉 2 )∣∣∣∣ eq = −b r(b)f ′(r(b)). Recall

  13. The effect of modified ijuk fibers to crystallinity of polypropylene composite

    Science.gov (United States)

    Prabowo, I.; Nur Pratama, J.; Chalid, M.

    2017-07-01

    Nowadays, plastics becomes concern associated with its degradation and environmental issues. It has led studies to develop an environmental-friendly material. To minimize the impact of those problems, recently the usage of natural fibers as a filler are introduced because of biodegradability and availability. The promising natural fiber is “ijuk” fiber from Arenga pinnata plant as a filler and polypropylene (PP) polymer as a matrix. Unfortunately, the natural fibers and polymers have the different properties on which polymers are polar while natural fibers are non-polar so that reducing the compatibility and resulting the poor crystallinity. To enhance the compatibility and crystallinity, ijuk fibers were prepared by multistage treatments including alkalinization with 5 and 10% sodium hydroxide (NaOH), oxidation with 3 and 6% sodium hypochlorite (NaClO) and hydrolysis with 20% sulphuric acid (H2SO4) in sequences. The purposes of multistage treatments are to remove the components such as lignin, wax, hemicellulose, to cause an oxidative fragmentation of remaining lignin and to annihilate the amorphous parts respectively. Fourier-Transform Infrared (FTIR) confirms the compatibility meanwhile Differential Scanning Calorimetry (DSC) reveals the crystallinity and Scanning Electron Microscope (SEM) displays surface morphology of polypropylene. The experiments were revealing that the effects of “ijuk” fibers by the multistage treatments of 5 and 10% NaOH resulting the crystallinity of polypropylene around 31.2 and 27.64% respectively compared to the crystallinity before adding the “ijuk” fibers for 16.8%. It indicates that the entire treatments increasing the compatibility and crystallinity of polypropylene. In addition, the use of 5% NaOH offers the better crystallinity than non-treated polypropylene. The experiments conclude that by adding alkalinized “ijuk” fibers of multistage treatments can increase the compatibility and crystallinity of polypropylene.

  14. Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly ( ethylene terephthalate ) (PET) and polyethylene ( PE ) as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable ealcium phosphate solution supplemented with laminin ( LCP solution ). The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin- apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite composite coating.

  15. Workshop on hydrology of crystalline basement rocks

    Energy Technology Data Exchange (ETDEWEB)

    Davis, S.N. (comp.)

    1981-08-01

    This workshop covered the following subjects: measurements in relatively shallow boreholes; measurement and interpretation of data from deep boreholes; hydrologic properties of crystalline rocks as interpreted by geophysics and field geology; rock mechanics related to hydrology of crystalline rocks; the possible contributions of modeling to the understanding of the hydrology of crystalline rocks; and geochemical interpretations of the hydrology of crystalline rocks. (MHR)

  16. Elaboration of submicron structures on PEEK polymer by femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Hammouti, S., E-mail: sabrina.hammouti@ec-lyon.fr [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Beaugiraud, B.; Salvia, M. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Mauclair, C. [LaHC, Université Jean Monnet, 18 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Pascale-Hamri, A. [MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Benayoun, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Valette, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France)

    2015-02-01

    Highlights: • We compare PEEK polymer under two crystalline forms: semi-crystalline and amorphous. • We assess topographical modifications of surface morphologies after femtosecond laser irradiation. • At low laser energy regime, there is an influence of the crystallinity rate on topographical features of surface morphologies. • At high laser energy regime, the contribution of the crystallinity tends to disappear. - Abstract: In this work, laser parameters initiating the emergence of periodic structures, so-called ripples on poly (ether ether ketone) (PEEK) surfaces, are investigated. PEEK was used in its semi-crystalline and amorphous forms. Polymer surfaces were treated locally by performing a matrix of laser impacts to highlight the influence of the crystallinity in ultrashort laser interaction. Different surface morphologies or ripples were analyzed by atomic force microscopy and optical interferometry. A map of the presence of these different morphologies according to the laser fluence and the number of pulses was established. Analysis by optical interferometry was carried out and led to the calculations of ablation efficiency. Some significant differences were demonstrated between amorphous and semi-crystalline surfaces. This work revealed topographical information on the local behavior of the irradiated material. Finally, the crystallinity rate of polymer surface seems to be a determinant factor for the periodic nanostructured appearance.

  17. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  18. Development of a high-throughput solution for crystallinity measurement using THz-Raman spectroscopy

    Science.gov (United States)

    Roy, Anjan; Fosse, Jean-Charles; Fernandes, Filipe; Ringwald, Alexandre; Ho, Lawrence

    2017-02-01

    Rapid identification and the quantitative analysis of crystalline content and the degree of crystallinity is important in pharmaceuticals and polymer manufacturing. Crystallinity affects the bioavailability of pharmaceutical molecules and there is a strong correlation between the performance of polymers and their degree of crystallinity. Low frequency/THz-Raman spectroscopy has enabled determination of crystalline content in materials as a complementary method to X-ray powder diffraction. By incorporating motion stages and microplates, we have extended the applicability of THz-Raman technology to high-throughput screening applications. We describe here a complete THz-Raman microplate reader, with integrated laser, optics, spectrograph and software that are necessary for detecting low-frequency Raman signals. In powder materials scattering is also affected by particle size and the presence of cavities, which lead to a lack of precision and repeatability in Raman intensity measurements. We address this problem by spatial averaging using specific stage motion patterns. This design facilitates rapid and precise measurement of low-frequency vibrational modes, differentiation of polymorphs and other structural characteristics for applications in pharmaceuticals, nano- and bio-materials and for the characterization of industrial polymers where XRPD is commonly used.

  19. Crystalline 'Genes' in Metallic Liquids

    CERN Document Server

    Sun, Yang; Ye, Zhuo; Fang, Xiaowei; Ding, Zejun; Wang, Cai-Zhuang; Mendelev, Mikhail I; Ott, Ryan T; Kramer, M J; Ho, Kai-Ming

    2014-01-01

    The underlying structural order that transcends the liquid, glass and crystalline states is identified using an efficient genetic algorithm (GA). GA identifies the most common energetically favorable packing motif in crystalline structures close to the alloy's Al-10 at.% Sm composition. These motifs are in turn compared to the observed packing motifs in the actual liquid structures using a cluster-alignment method which reveals the average topology. Conventional descriptions of the short-range order, such as Voronoi tessellation, are too rigid in their analysis of the configurational poly-types when describing the chemical and topological ordering during transition from undercooled metallic liquids to crystalline phases or glass. Our approach here brings new insight into describing mesoscopic order-disorder transitions in condensed matter physics.

  20. Design of Cylinder Conformal Antenna Arrays Based on LCP Flexible Material%基于LCP柔性材料的柱面共形阵列天线设计

    Institute of Scientific and Technical Information of China (English)

    赵满

    2013-01-01

    采用新型液晶高分子聚合物(LCP)作为基板材料,通过模拟仿真设计了一款工作频率在35GHz的四单元微带共形贴片天线.该共形贴片阵列的增益可以达到13.2dB,3dB波瓣宽度为42.2°,副瓣电平达到-20.6dB.

  1. LCP correlations with improved resolution

    Science.gov (United States)

    Heilborn, Lauren; McIntosh, Alan; Jedele, Andrea; Youngs, Mike; Zarrella, Andrew; Yennello, Sherry

    2016-09-01

    Nuclear Equation of State (EoS) is important to a fundamental understanding of nuclear matter. The density dependence of the asymmetry energy, the least constrained term in the EoS, is critical to describing exotic systems such as neutron-rich heavy-ion collisions and neutron stars. Correlation functions of particles emitted in heavy ion reactions (such a p-p correlations) have been predicted to be sensitive to the asymmetry energy. In order to measure correlation functions with high resolution, the Forward Array Using Silicon Technology (FAUST) at the Cyclotron Institute at Texas A&M University has been recently re-commissioned with position-sensitive silicons as the delta-E detectors. A new method of position calibration for FAUST has been developed to take advantage of the 200um position resolution within each detector. Data has been collected from reactions of 40Ar +70Zn, 40Ar +58Fe and 40Ca +58Ni at 40 MeV/nucleon. The three systems allow correlation functions to be compared for systems with varying (N-Z)/A while holding constant either the total charge or the total mass. Light charged particles have been measured, and preliminary investigation of correlations from this campaign will be shown. Transport simulations will also be compared and presented.

  2. Positronium diffusion in crystalline polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Serna, J. (Dept. de Fisica de Materiales, Univ. Complutense, Madrid (Spain))

    1990-12-16

    The analysis in four components of the positron lifetime spectra of nine different and structurally well characterised lamellar polyethylene samples has allowed to associate the two longest-lived components to positronium annihilation in the crystalline and amorphous phases. Further assumption on positronium tunneling through the interface between both phases, and a simple geometrical model, led to a value for the positronium diffusion coefficient in the crystalline phase of the order of 10{sup -4} cm{sup 2}/s. Interfaces have thicknesses around 1.5 nm and are shallow traps for positronium. (orig.).

  3. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  4. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  5. Polarized photoluminescence from nematic and chiral- nematic liquid crystalline films

    Science.gov (United States)

    Conger, Brooke Morgan

    Polarization control is key to optoelectronics in terms of the processing and display of optical information. In principle, photonic or electronic excitation of anisotropic films should result in polarized light emission. Because of spontaneous molecular self-assembly, liquid crystals are ideal for the exploration of polarized luminescence. Although most studies on polarized luminescence have been based on liquid crystalline fluid films, solid films are preferred in view of morphological stability. Therefore, the theme of my thesis is the study of polarized luminescence from various fluorescent liquid crystal systems. From the fundamental perspective, a theory modeling the process of polarized photoluminescence was validated using fluorophore doped fluid liquid crystal films. To provide the morphological stability crucial to practical application, polarized fluorescence using vitrifiable and polymeric liquid crystals functionalized with fluorescent moieties was investigated. In addition, liquid crystalline π- conjugated polymers were synthesized and characterized as a new class of optical polymers. The effect of the emission source on achievable polarization from pyrene and carbazole systems was also elucidated. The main observations are as follows: (1) The observed degrees of polarization for all fluorescent liquid crystal systems were found to agree with the theories governing polarized fluorescence. (2) Low molar mass vitrifiable and polymeric liquid crystalline cyanoterphenyl and cyanotolane derivatives were found to yield moderate polarized fluorescence. Monomer emission was established as the decay pathway for the precursors and cyclohexane and polymethacrylate derivatives. (3) Ordered solid films from thiophene and p-phenylene π-conjugated polymers were found to induce significant degrees of polarized fluorescence. (4) Emission from glass-forming pyrenyl derivatives exhibited excimer emission in dilute solution and neat film, whereas in solid hosts it was

  6. Syntheses and studies of acetylenic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Yiwei, Ding

    1994-03-03

    Based on new diiodo aryl compounds a series of novel soluble polymers, poly(2,5-dialkoxy-1,4-phenyleneethynylene)s (PPE polymers) were synthesized using palladium-catalysis. The molecular weights (MW) range from 8,000 to 40,000. Properties such as absorption, fluorescence, and conductivity were studied. A PPE polymer with butoxy side chain exhibits a weak electrical conductivity ({sigma} = 10{sup {minus}3} S/cm) after doping with AsF{sub 5}. Absorption spectra in THF solution at room temperature (RT) show a maximum at 440 nm. However, absorption spectra of PPE polymers in the film state at (RT) show a maximum at 480 nm. PPE polymer-based light emitting diode (LED) devices have been prepared; greenish light from these LED devices can be observed. Poly(ethynylene-p-arylene-ethynylene-silylene)s were synthesized through the same palladium-catalyzed polymerization; MWs are between 6,000 and 82,000. Absorption and fluorescence were studied. Some of these polymers exhibit thermotropic liquid crystalline properties. In addition, nonlinear optical properties were briefly examined. Poly(silylene-ethynylene) homopolymers as well as alternating copolymers were synthesized through a novel palladium-catalyzed polymerization; MWs range from 56 {times} 10{sup 3} to 5.3 {times} 10{sup 3}. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  7. Syntheses and studies of acetylenic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Yiwei, Ding [Iowa State Univ., Ames, IA (United States)

    1994-03-03

    Based on new diiodo aryl compounds a series of novel soluble polymers, poly(2,5-dialkoxy-1,4-phenyleneethynylene)s (PPE polymers) were synthesized using palladium-catalysis. The molecular weights (MW) range from 8,000 to 40,000. Properties such as absorption, fluorescence, and conductivity were studied. A PPE polymer with butoxy side chain exhibits a weak electrical conductivity (σ = 10-3 S/cm) after doping with AsF5. Absorption spectra in THF solution at room temperature (RT) show a maximum at 440 nm. However, absorption spectra of PPE polymers in the film state at (RT) show a maximum at 480 nm. PPE polymer-based light emitting diode (LED) devices have been prepared; greenish light from these LED devices can be observed. Poly(ethynylene-p-arylene-ethynylene-silylene)s were synthesized through the same palladium-catalyzed polymerization; MWs are between 6,000 and 82,000. Absorption and fluorescence were studied. Some of these polymers exhibit thermotropic liquid crystalline properties. In addition, nonlinear optical properties were briefly examined. Poly(silylene-ethynylene) homopolymers as well as alternating copolymers were synthesized through a novel palladium-catalyzed polymerization; MWs range from 56 x 103 to 5.3 x 103. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  8. STAR POLYMERS

    OpenAIRE

    Ch. von Ferber; Yu.Holovatch

    2002-01-01

    It is our great pleasure to present a collection of papers devoted to theoretical, numerical, and experimental studies in the field of star polymers. Since its introduction in the early 80-ies, this field has attracted increasing interest and has become an important part of contemporary polymer physics. While research papers in this field appear regularly in different physical and chemical journals, the present collection is an attempt to join together the studies of star polymers showing the...

  9. Static and Dynamic Properties of Semi-Crystalline Polyethylene

    Directory of Open Access Journals (Sweden)

    Ming-ming Xu

    2016-03-01

    Full Text Available Properties of extruded polymers are strongly affected by molecular structure. For two different semi-crystalline polymers, low-density polyethylene (LDPE and ultra-high molecular weight polyethylene (UHMWPE, this investigation measures the elastic modulus, plastic flow stress and strain-rate dependence of yield stress. Also, it examines the effect of molecular structure on post-necking tensile fracture. The static and dynamic material tests reveal that extruded UHMWPE has a somewhat larger yield stress and much larger strain to failure than LDPE. For both types of polyethylene, the strain at tensile failure decreases with increasing strain-rate. For strain-rates 0.001–3400 s−1, the yield stress variation is accurately represented by the Cowper–Symonds equation. These results indicate that, at high strain rates, UHMWPE is more energy absorbent than LDPE as a result of its long chain molecular structure with few branches.

  10. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  11. Structure and Refinement of Ordered Aromatic Heterocyclic Polymers by Diffraction Methods: Application of Results to Electro-Optic Phenomena.

    Science.gov (United States)

    1988-02-01

    polymers, fiber structure, polybenzothiazoles, 07 04 rigid rod polymers, likad-atom least-squares P-BT 11 1 04 ladder polymer, polybenzoxazoles I...of polymers. The attainment, In these polymers, of mechanical and thermal oxidative properties comparable or superior to those obtained with fiber ...applicability of the LALS refinement method to high performance fibers has been reported. We have Investigated oriented fibers of semi-crystalline poly(aryl

  12. SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTAL POLYMERS WITH T-SHAPED TWO-DIMENSIONAL MESOGENIC UNITS (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    LI Zifa; ZHENG Shijun; ZHANG Shuyuan; CAO Shaokui; LI Lei; LIU Guangsheng; ZHOU Qifeng

    1997-01-01

    A series of liquid crystalline polymers with T-shaped two-dimensional mesogenic units were synthesized via low temperature solution polycondensation of 2-(4'-alkoxy-phenyl) hydroquinone with various diacyl dichlorides. The polymers were found to be nematic and shown thermotropic liquid crystalline behaviors through observations using DSC, polarized microscopy and X-ray diffraction. The melting temperature Tm and the isotropization temperature Ti of the polymers change regularly with varying of the monomer structures.

  13. Generic Crystalline Disposal Reference Case

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott Leroy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harp, Dylan Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Perry, Frank Vinton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wang, Yifeng [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-20

    A generic reference case for disposal of spent nuclear fuel and high-level radioactive waste in crystalline rock is outlined. The generic cases are intended to support development of disposal system modeling capability by establishing relevant baseline conditions and parameters. Establishment of a generic reference case requires that the emplacement concept, waste inventory, waste form, waste package, backfill/buffer properties, EBS failure scenarios, host rock properties, and biosphere be specified. The focus in this report is on those elements that are unique to crystalline disposal, especially the geosphere representation. Three emplacement concepts are suggested for further analyses: a waste packages containing 4 PWR assemblies emplaced in boreholes in the floors of tunnels (KBS-3 concept), a 12-assembly waste package emplaced in tunnels, and a 32-assembly dual purpose canister emplaced in tunnels. In addition, three failure scenarios were suggested for future use: a nominal scenario involving corrosion of the waste package in the tunnel emplacement concepts, a manufacturing defect scenario applicable to the KBS-3 concept, and a disruptive glaciation scenario applicable to both emplacement concepts. The computational approaches required to analyze EBS failure and transport processes in a crystalline rock repository are similar to those of argillite/shale, with the most significant difference being that the EBS in a crystalline rock repository will likely experience highly heterogeneous flow rates, which should be represented in the model. The computational approaches required to analyze radionuclide transport in the natural system are very different because of the highly channelized nature of fracture flow. Computational workflows tailored to crystalline rock based on discrete transport pathways extracted from discrete fracture network models are recommended.

  14. polyMOFs: A Class of Interconvertible Polymer-Metal-Organic-Framework Hybrid Materials.

    Science.gov (United States)

    Zhang, Zhenjie; Nguyen, Ha Thi Hoang; Miller, Stephen A; Cohen, Seth M

    2015-05-18

    Preparation of porous materials from one-dimensional polymers is challenging because the packing of polymer chains results in a dense, non-porous arrangement. Herein, we demonstrate the remarkable adaptation of an amorphous, linear, non-porous, flexible organic polymer into a three-dimensional, highly porous, crystalline solid, as the organic component of a metal-organic framework (MOF). A polymer with aromatic dicarboxylic acids in the backbone functioned as a polymer ligand upon annealing with Zn(II), generating a polymer-metal-organic framework (polyMOF). These materials break the dogma that MOFs must be prepared from small, rigid ligands. Similarly, polyMOFs contradict conventional polymer chemistry by demonstrating that linear and amorphous polymers can be readily coaxed into a highly crystalline, porous, three-dimensional structure by coordination chemistry.

  15. 大型体育场馆工程项目LCP融资模式研究%Study on the LCP Financial Model in Large-scale Sports Venue Construction Projects

    Institute of Scientific and Technical Information of China (English)

    耿宝权

    2011-01-01

    Large-scale sports venue onstruction projects are usually marked by huge investment requirements, lack of diversified financing channel and heavy reliance on a certain few investment sources, and the disengagement of construnction with operation. The paper designs a life-circle partnership (LCP) financing model to deal with these insufficiencies, which is based on the operator-participated project financing model, aiming at the integration of the decision-making and operation phases of the projects. It is argued that the LCP model not only brings the operating party into the different stages of the life circle of the projects, but can also provide matching risk distribution, profiting sharing, and trust mechanism to guarantee the realization of both public and commercial interests.%大型体育场馆项目往往存在投资额巨大,融资模式单一,且建设和运营相脱节的现象.为了保证项目在全寿命期内的成功,设计了大型体育场馆工程项目的LCP融资模式.LCP模式不但将经营方引人项目的全生命周期,而且还设计了与该模型相匹配的风险分担、利益共享和信任机制,以保证公共利益和商业利益的实现.

  16. Crystalline nanocellulose/lauric arginate complexes.

    Science.gov (United States)

    Chi, Kai; Catchmark, Jeffrey M

    2017-11-01

    As a novel sustainable nanomaterial, crystalline nanocellulose (CNC) possesses many unique characteristics for emerging applications in coatings, emulsions, paints, pharmaceutical formulations, and other aqueous composite systems where interactions with oppositely charged surfactants are commonly employed. Herein, the binding interactions between sulfated CNC and a novel biologically-derived cationic surfactant lauric arginate (LAE) were comprehensively examined. Ionic strength and solution pH are two crucial factors in determining the adsorption of LAE to the CNC surface. Three different driving forces were identified for CNC-LAE binding interactions. Additionally, it was found that the adsorption of LAE to the CNC surface could notably impact the surface potential, aggregation state, hydrophobicity and thermal stability of the CNC. This work provides insights on the binding interactions between oppositely charged CNC and surfactants, and highlights the significance of optimizing the concentration of surfactant required to ionically decorate CNC for its enhanced dispersion and compatibilization in non-polar polymer matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination.

    Science.gov (United States)

    Liu, Baoxia; Huang, Yankai; Zhu, Xu; Hao, Yuanqiang; Ding, Yujie; Wei, Wei; Wang, Qi; Qu, Peng; Xu, Maotian

    2016-03-17

    Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg(2+) detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb(3+) from the quenching effect of O-H vibration in water molecules. The subsequent addition of Hg(2+) into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg(2+). As a kind of Hg(2+) nanosensor, the probe exhibited excellent selectivity for Hg(2+) and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg(2+) in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging.

  18. Polymers & People

    Science.gov (United States)

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  19. Self-healing polymers

    Science.gov (United States)

    Klein, Daniel J. (Inventor)

    2011-01-01

    A three dimensional structure fabricated from a self-healing polymeric material, comprising poly(ester amides) obtained from ethylene glycol, azelaic acid and 1,1-aminoundecanoic acid, wherein polymeric material has a melt index above 2.5 g/10 min. as determined by ASTM D1238 at 190.degree. C. and 2.16kg, impact resistance and ductility sufficient to resist cracking and brittle fracture upon impact by a 9 mm bullet fired at a temperature of about 29.degree. C. at subsonic speed in a range from about 800 feet/sec to about 1000 feet/sec. It has been determined that the important factors necessary for self-healing behavior of polymers include sufficient impact strength, control of the degree of crystallinity, low melting point and the ability to instantly melt at impacted area.

  20. Photocontrollable liquid-crystalline actuators

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Haifeng [Top Runner Incubation Center for Academia-Industry Fusion and Department of Materials and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan); Ikeda, Tomiki [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-11, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2011-05-17

    Coupling photochromic molecules with liquid crystalline (LC) materials enables one to reversibly photocontrol unique LC features such as phase transition, photoalignment, and molecular cooperative motion. LC elastomers show photomechanical and photomobile properties, directly converting light energy into mechanical energy. In well-defined LC block copolymers, regular patternings of nanostructures in macroscopic scales are fabricated by photo-manipulation of LC actuators. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Liquid Crystalline Esters of Dibenzophenazines

    Directory of Open Access Journals (Sweden)

    Kevin John Anthony Bozek

    2015-01-01

    Full Text Available A series of esters of 2,3,6,7-tetrakis(hexyloxydibenzo[a,c]phenazine-11-carboxylic acid was prepared in order to probe the effects of the ester groups on the liquid crystalline behavior. These compounds exhibit columnar hexagonal phases over broad temperature ranges. Variations in chain length, branching, terminal groups, and the presence of cyclic groups were found to modify transition temperatures without substantially destabilizing the mesophase range.

  2. EXAFS studies of crystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, G.S.; Georgopoulos, P.

    1982-01-01

    The application of extended x-ray absorption fine structure (EXAFS) technique to the study of crystalline materials is discussed, and previously published work on the subject is reviewed with 46 references being cited. The theory of EXAFS, methods of data analysis, and the experimental techniques, including those based on synchrotron and laboratory facilities are all discussed. Absorption and fluorescence methods of detecting EXAFS also receive attention. (BLM)

  3. Inelastic deformation in crystalline rocks

    Science.gov (United States)

    Rahmani, H.; Borja, R. I.

    2011-12-01

    The elasto-plastic behavior of crystalline rocks, such as evaporites, igneous rocks, or metamorphic rocks, is highly dependent on the behavior of their individual crystals. Previous studies indicate that crystal plasticity can be one of the dominant micro mechanisms in the plastic deformation of crystal aggregates. Deformation bands and pore collapse are examples of plastic deformation in crystalline rocks. In these cases twinning within the grains illustrate plastic deformation of crystal lattice. Crystal plasticity is governed by the plastic deformation along potential slip systems of crystals. Linear dependency of the crystal slip systems causes singularity in the system of equations solving for the plastic slip of each slip system. As a result, taking the micro-structure properties into account, while studying the overall behavior of crystalline materials, is quite challenging. To model the plastic deformation of single crystals we use the so called `ultimate algorithm' by Borja and Wren (1993) implemented in a 3D finite element framework to solve boundary value problems. The major advantage of this model is that it avoids the singularity problem by solving for the plastic slip explicitly in sub steps over which the stress strain relationship is linear. Comparing the results of the examples to available models such as Von Mises we show the significance of considering the micro-structure of crystals in modeling the overall elasto-plastic deformation of crystal aggregates.

  4. Biocompatibility of crystalline opal nanoparticles

    Directory of Open Access Journals (Sweden)

    Hernández-Ortiz Marlen

    2012-10-01

    Full Text Available Abstract Background Silica nanoparticles are being developed as a host of biomedical and biotechnological applications. For this reason, there are more studies about biocompatibility of silica with amorphous and crystalline structure. Except hydrated silica (opal, despite is presents directly and indirectly in humans. Two sizes of crystalline opal nanoparticles were investigated in this work under criteria of toxicology. Methods In particular, cytotoxic and genotoxic effects caused by opal nanoparticles (80 and 120 nm were evaluated in cultured mouse cells via a set of bioassays, methylthiazolyldiphenyl-tetrazolium-bromide (MTT and 5-bromo-2′-deoxyuridine (BrdU. Results 3T3-NIH cells were incubated for 24 and 72 h in contact with nanocrystalline opal particles, not presented significant statistically difference in the results of cytotoxicity. Genotoxicity tests of crystalline opal nanoparticles were performed by the BrdU assay on the same cultured cells for 24 h incubation. The reduction of BrdU-incorporated cells indicates that nanocrystalline opal exposure did not caused unrepairable damage DNA. Conclusions There is no relationship between that particles size and MTT reduction, as well as BrdU incorporation, such that the opal particles did not induce cytotoxic effect and genotoxicity in cultured mouse cells.

  5. PREPARATION AND CHARACTERIZATION OF SHISH-KEBAB TYPE LIQUID CRYSTALLINE POLY(p-PHENYLENEVINYLENE)

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Kazuo Akagi; Qun Xu; Shao-kui Cao; Qi-feng Zhou

    2006-01-01

    Novel shish-kebab type liquid crystalline poly(p-phenylenevinylene) derivatives were synthesized by Stille coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,2-bis(tributylstannyl)ethylene (monomer 2). The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.

  6. Synthesis and characterization of liquid-crystalline supramolecular architecture by a combination of molecular recognition and polymerization reaction

    Science.gov (United States)

    Ahn, Cheol-Hee

    In nature, self-assembly with well defined shapes obtained from combinations of polymeric building blocks with complex architecture are abundant since they are responsible for the production of structural materials and for the generation of some of the most efficient mechanisms. One of the many roles liquid crystallinity plays in natural systems is in their self-assembly and organization. The assembly of these complex natural systems is largely under thermodynamic control which is manipulated by their liquid crystallinity. The goal of this thesis is to use Nature as a model for the development of new synthetic concepts and strategies in the field of polymer science. The two models selected are rod-like and icosahedral viruses. The strategy involved in this thesis requires the design of libraries of monodendritic building blocks with well defined flat tapered and conical shapes which self-assemble into cylindrical and respectively spherical shapes. By analogy with viruses these supermolecules will generated hexagonal columnar and spherical cubic thermotropic phases. These liquid crystalline phases allow the determination of their shape by X-ray diffraction and Scanning Force Microscopy. Libraries of flat tapered and conical monodendritic building blocks will be functionalized with polymerizable groups and polymerized to generate the first examples of polymers of cylindrical and spherical shapes with diameter and length, and diameter controlled at the nanoscale level. The organization of these dendritic monomers in a liquid crystalline assembly is also used to aggregate their polymerizable groups in a reactor of artificially enhanced concentration and restricted geometry during the polymerization process and therefore, generate a new approach to the control of polymerization. The resulting liquid crystallinity provides access to the thermodynamically controlled assembly and characterization of these newly developed polymers. With few exceptions, there is no precedent

  7. SYNTHESIS AND MESOMORPHIC PROPERTIES OF FISHBONE-LIKE LIQUID CRYSTALLINE POLYSILSESQUIOXANES Ⅰ. FISHBONE-LIKE, β-DIKETONE-BASED LIQUID CRYSTALLINE POLYSILSESQUIOXANES AND THEIR COPPER COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rongben; XIE Zushou; WAN Youzhi; JIN Sunzhi; HOU Jianan

    1993-01-01

    Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes (FBDKLCP'S),homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with Mw of 104 is thermotroic liquid crystalline polymer and its clearing temperatures Ti's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200 ℃ . Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in Td,l's and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.

  8. Characterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phases

    KAUST Repository

    Sweetnam, Sean

    2014-10-08

    Theoretical and experimental studies suggest that energetic offsets between the charge transport energy levels in different morphological phases of polymer:fullerene bulk heterojunctions may improve charge separation and reduce recombination in polymer solar cells (PSCs). In this work, we use cyclic voltammetry, UV-vis absorption, and ultraviolet photoelectron spectroscopy to characterize hole energy levels in the polymer phases of polymer:fullerene bulk heterojunctions. We observe an energetic offset of up to 150 meV between amorphous and crystalline polymer due to bandgap widening associated primarily with changes in polymer conjugation length. We also observe an energetic offset of up to 350 meV associated with polymer:fullerene intermolecular interactions. The first effect has been widely observed, but the second effect is not always considered despite being larger in magnitude for some systems. These energy level shifts may play a major role in PSC performance and must be thoroughly characterized for a complete understanding of PSC function.

  9. Statistical conjugated polymers comprising optoelectronically distinct units.

    Science.gov (United States)

    Hollinger, Jon; Sun, Jing; Gao, Dong; Karl, Dominik; Seferos, Dwight S

    2013-03-12

    Poly(3-heptylselenophene)-stat-poly(3-hexylthiophene) is synthesized and characterized in terms of its crystallinity and performance in an organic photovoltaic (OPV) cell. Despite the random distribution of units along the polymer main chain, the material is semi-crystalline, as demonstrated by differential scanning calorimetry and wide-angle X-ray diffraction. Thin-film absorption suggests an increased compatibility than seen with 3-hexylselenophene monomer. Optoelectronic properties are an average of the two homopolymers, and OPV performance is enhanced by a broadened absorption profile and a favorable morphology.

  10. The effect of the stretching of PLA extruded films on their crystallinity and gas barrier properties

    Science.gov (United States)

    Guinault, A.; Menary, G. H.; Courgneau, C.; Griffith, D.; Ducruet, V.; Miri, V.; Sollogoub, C.

    2011-05-01

    Driven by environmental concerns, new polymers based on renewable resources are arriving on the market to replace conventional polymers, obtained from petroleum, for different applications like food packaging. One of the most prominent polymers among these materials is poly(lactic acid) (PLA), a biodegradable, thermoplastic, aliphatic polyester derived from renewable resources, such as corn starch (in the USA) or sugarcanes (in the rest of the world). However this polymer presents different disadvantages and especially low gas barrier properties [1]. Thermal crystallization can be used to increase its gas barrier properties but long times are necessary [2] and are not compatible with an industrial process. Another way to increase the gas barrier properties consists in stretching the film in order to increase its crystallinity and so its diffusion coefficient. We have prepared stretched PLA films with different stretch ratio and we have studied the effect of the stretching parameters on the gas barrier properties of PLA films. Finally we compared this process with the isothermal crystallization process by taking into account the crystallinity degree and the crystalline morphology.

  11. Effects of hydrolysis degree and molecular weight in PVAL crystallinity; Influencia do grau de hidrolise e da massa molar na cristalinidade do VAL

    Energy Technology Data Exchange (ETDEWEB)

    Mansur, Alexandra A.P.; Oliveira, Fagner; Mansur, Herman S. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica e Materiais]. E-mail: hmansur@demet.ufmg.br

    2005-07-01

    Poly(vinyl alcohol) (PVAL) is a relatively simple polymer of great interest in many applications. Poly(vinyl alcohol) commercial grades vary in polymerization degree (GP) and hydrolysis degree (GH) which affect several PVAL properties including crystallinity. The aim of this work was to evaluate the influence of GH and GP on PVAL crystallinity using WAXS (Wide Angle X Ray Scattering) analysis. Based on the results, the degree of hydrolysis has presented an important influence on PVAL crystallinity. On the other hand, the amount of crystalline phase did not seem to be significantly affected by PVAL polymerization degree. (author)

  12. SYNTHESIS AND CHARACTERIZATION OF AROMATIC LIQUID CRYSTALLINE COPOLYESTERS WITH REGULAR SEQUENCE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    LIN Qinghuang; WANG Huifen; LIU Deshan; ZHOU Qixiang

    1990-01-01

    Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Schotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage,thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters . The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers.

  13. Photochemical stability of nonlinear optical chromophores in polymeric and crystalline materials.

    Science.gov (United States)

    Rezzonico, Daniele; Kwon, Seong-Ji; Figi, Harry; Kwon, O-Pil; Jazbinsek, Mojca; Günter, Peter

    2008-03-28

    We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light excitations, the polymeric compound degrades through an indirect process, while the DAT2 crystal follows a slow direct process. We show that chromophores in a crystalline environment exhibit three orders of magnitude better photostability as compared to guest-host polymer composites.

  14. Organometallic Polymers.

    Science.gov (United States)

    Carraher, Charles E., Jr.

    1981-01-01

    Reactions utilized to incorporate a metal-containing moiety into a polymer chain (addition, condensation, and coordination) are considered, emphasizing that these reactions also apply to smaller molecules. (JN)

  15. Polymers All Around You!

    Science.gov (United States)

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers…

  16. Charge-transport model for conducting polymers

    Science.gov (United States)

    Dongmin Kang, Stephen; Jeffrey Snyder, G.

    2016-11-01

    The growing technological importance of conducting polymers makes the fundamental understanding of their charge transport extremely important for materials and process design. Various hopping and mobility edge transport mechanisms have been proposed, but their experimental verification is limited to poor conductors. Now that advanced organic and polymer semiconductors have shown high conductivity approaching that of metals, the transport mechanism should be discernible by modelling the transport like a semiconductor with a transport edge and a transport parameter s. Here we analyse the electrical conductivity and Seebeck coefficient together and determine that most polymers (except possibly PEDOT:tosylate) have s = 3 and thermally activated conductivity, whereas s = 1 and itinerant conductivity is typically found in crystalline semiconductors and metals. The different transport in polymers may result from the percolation of charge carriers from conducting ordered regions through poorly conducting disordered regions, consistent with what has been expected from structural studies.

  17. Bulk nano-crystalline alloys

    OpenAIRE

    T.-S. Chin; Lin, C. Y.; Lee, M.C.; R.T. Huang; S. M. Huang

    2009-01-01

    Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and confirmed successful on another Fe-based BMG Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed cr...

  18. Effect of polymer type and drug dose on the in vitro and in vivo behavior of amorphous solid dispersions

    DEFF Research Database (Denmark)

    Knopp, Matthias Manne; Chourak, Nabil; Khan, Fauzan

    2016-01-01

    , the amorphous solid dispersions with the hydrophilic polymers PVP and HPMC led to higher areas under both, the in vitro dissolution and the plasma concentration-time curves (AUC) compared to crystalline and amorphous CCX for all doses. In contrast, the amorphous solid dispersion with the hydrophobic polymer PVA...... showed a lower AUC both in vitro and in vivo than crystalline CCX. For crystalline CCX and CCX:PVA, the in vitro AUC was limited by the low solubility of the drug and the slow release of the drug from the hydrophobic polymer, respectively. For the supersaturating formulations, amorphous CCX, CCX...

  19. Clinical Efficacy Analysis of Application LCP and MIPPO Technology for Distal Tibial Fracture%LCP微创治疗胫骨中下段骨折的临床疗效分析

    Institute of Scientific and Technical Information of China (English)

    陈军; 石卫星; 王冶; 付伦

    2014-01-01

    Objective To research combination LCP and MIPPO surgical treatment for distal tibial fracture.Methods From April 2009 to March 2011,34 cases of distal tibial fractures were treated with locking compression plate(LCP)combined with MIPPO, including 21 males and 13 females;aged 23 to 62 years, with an average of 43.8 years. Record incision length, amount of bleeding, operative time, hospital stay, fracture healing time, postoperative functional indicators Etc. Results Al fracture reached bone healing . 31 patients were followed up for 12 to 36 months, 3 were lost. Al fractures were healed in 13~21 weeks after surgery, an average of 14 weeks. There are no complications such as vascular injury、nonunion and fixation loosening, fracture. Conclusion Use of locking compression plate (LCP)combined with MIPPO technique in the treatment of distal Tibial fracture can reduce can reduce the range of periosteal stripping, improve the success rate of surgery and is conducive to the recovery of limb function.%目的:探讨运用经皮(minimal y invasive percutaneus plate osteosynthesis, MIPPO)技术结合锁定加压钢板(LCP)内固定术治疗胫骨中下段骨折的方法和临床意义。方法2009年4月~2011年3月收治胫骨中下段骨折患者34例,其中男21例,女13例;年龄23~62岁,平均43.8岁。采用经皮微创钢板固定治疗。记录的切口长度、出血量、手术时间、住院时间、骨折愈合时间、术后功能等指标进行比较。结果患者均一期愈合。31例随访12~36个月,3例失访。骨折全部愈合,愈合时间为术后13~21w,平均14w。无神经血管损伤、骨折不愈合和内固定松动、断裂等并发症。结论微创经皮技术结合LCP内固定是较好治疗胫骨中下段骨折的方法,能减少对骨膜剥离,提高手术成功率,有利于患者下肢功能的恢复。

  20. Molecular Processing of Polymers with Cyclodextrins

    Science.gov (United States)

    Tonelli, Alan E.

    We summarize our recent studies employing the cyclic starch derivatives called cyclodextrins (CDs) to both nanostructure and functionalize polymers. Two important structural characteristics of CDs are taken advantage of to achieve these goals. First the ability of CDs to form noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical with diameters of ˜ 0.5 - 1.0 nm. α-, β-, and γ-CD contain six, seven, and eight α-1,4-linked glucose units, respectively. Warm water washing of polymer-CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serves to remove the host CDs and results in the coalescence of the guest polymers into solid samples. When guest polymers are coalesced from the CD-ICs by removing their host CDs, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. Molecularly mixed, intimate blends of two or more polymers that are normally immiscible can be obtained from their common CD-ICs, and the phase segregation of incompatible blocks can be controlled (suppressed or increased) in CD-IC coalesced block copolymers. In addition, additives may be more effectively delivered to polymers in the form of their crystalline CD-ICs or soluble CD-rotaxanes. Secondly, the many hydroxyl groups attached to the exterior rims of CDs, in addition to conferring water solubility, provide an opportunity to covalently bond them to polymers either during their syntheses or via postpolymerization reactions. Polymers containing CDs in their backbones or attached to their side chains are observed to more readily accept and retain additives, such as dyes and fragrances. Processing with CDs can serve to both nanostructure and functionalize polymers, leading to greater understanding of their behaviors

  1. Genetics of Bietti Crystalline Dystrophy.

    Science.gov (United States)

    Ng, Danny S C; Lai, Timothy Y Y; Ng, Tsz Kin; Pang, Chi Pui

    2016-01-01

    Bietti crystalline dystrophy (BCD) is an inherited retinal degenerative disease characterized by crystalline deposits in the retina, followed by progressive atrophy of the retinal pigment epithelium (RPE), choriocapillaris, and photoreceptors. CYP4V2 has been identified as the causative gene for BCD. The CYP4V2 gene belongs to the cytochrome P450 superfamily and encodes for fatty acid ω-hydroxylase of both saturated and unsaturated fatty acids. The CYP4V2 protein is localized most abundantly within the endoplasmic reticulum in the RPE and is postulated to play a role in the physiological lipid recycling system between the RPE and photoreceptors to maintain visual function. Electroretinographic assessments have revealed progressive dysfunction of rod and cone photoreceptors in patients with BCD. Several genotypes have been associated with more severe phenotypes based on clinical and electrophysiological findings. With the advent of multimodal imaging with spectral domain optical coherence tomography, fundus autofluorescence, and adaptive optics scanning laser ophthalmoscopy, more precise delineation of BCD severity and progression is now possible, allowing for the potential future development of targets for gene therapy.

  2. Preparation and characterization of the crystalline inclusion complexes between cyclodextrins and poly(1,3-dioxolane)

    Institute of Scientific and Technical Information of China (English)

    李景烨; 颜德岳; 陈群

    2002-01-01

    The preparation and characterization of the crystalline inclusion complexes between a polymeric guest, poly(1,3-dioxolane)(PDXL), and small-molecular hosts, cyclodextrins(CDs) are reported. It is observed that the polymer guest can form crystalline inclusion complexes with three kinds of cyclodextrins, which May be attributed to the high oxygen atom density in PDXL chain. The crystalline inclusion complexes were characterized with FTIR , TGA, X-ray diffraction, SEM, 1H NMR and 13C CP/MAS NMR spectroscopes. It was found that the crystalline inclusion complexes have higher temperature stability than the pure CDs. The X-ray powder diffraction patterns of the crystalline inclusion complexes proved that they have columnar structures. 13C CP/MAS NMR spectra of the crystalline inclusion complexes indicate that CDs adopt a more symmetrical confor-mation in the complexes, while pure CDs assume a less symmetrical conformation in the crystal without a guest inside their cavities. The morphology of the crystal was observed by means of SEM.

  3. Efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (termotratada y micropropagada de las variedades CP 65-357 y LCP 85-384 Effect of planting date on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated

    Directory of Open Access Journals (Sweden)

    Patricia A. Digonzelli

    2005-12-01

    Full Text Available Se evalúa el efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (micropropagada y termotratada de las variedades CP 65-357 y LCP 85-384, en condiciones de disponibilidad hídrica adecuada. La caña semilla micropropagada y termotratada (50ºC, 2 hs se plantó, con una densidad de 15 yemas/m, en tres épocas contrastantes: otoño, invierno y primavera. El material empleado estaba libre de escaldadura de la hoja (Xanthomonas albilineans y achaparramiento (Leifsonia xyli subsp. xyli. La época de plantación afectó todas las variables de la dinámica de la emergencia en las dos variedades y en ambos orígenes de la semilla. El origen afectó significativamente el inicio y la duración de la emergencia (t e y t50, pero no tuvo efecto en el porcentaje final ni en la tasa media de emergencia. La emergencia (% fue mayor en la plantación de octubre, que en las de mayo y agosto (59%, 35% y 45%, respectivamente. El te y el t50 fueron mayores en mayo que en agosto y octubre. La semilla micropropagada presentó, en general, valores de t e y t50 menores que la termotratada. La época de plantación fue el principal factor que afectó la dinámica de la emergencia de caña semilla de alta calidad de CP 65-357 y LCP 85-384. La variedad y el origen de la semilla afectaron significativamente, aunque en menor magnitud que la época de plantación, el inicio y la duración de la fase de emergencia.Planting date influence on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated, without humidity constraints, was evaluated. Material used was free from leaf scald disease (Xanthomonas albilineans and ratoon stunting disease (Leifsonia xyli subsp. xyli. Seed cane, micropropagated and hot-water treated (50ºC, 2 hours, was planted with a 15 buds/m density in three contrasting dates: autumn, winter and spring. The material was irrigated during the trial. Planting

  4. Approaches for Making High Performance Polymer Materials from Commodity Polymers

    Institute of Scientific and Technical Information of China (English)

    Xu Xi

    2004-01-01

    A brief surrey of ongoing research work done for improving and enhancing the properties of commodity polymers by the author and author's colleagues is given in this paper. A series of high performance polymers and polymer nanomaterials were successfully prepared through irradiation and stress-induced reactions of polymers and hydrogen bonding. The methods proposed are viable, easy in operation, clean and efficient.1. The effect of irradiation source (UV light, electron beam, γ -ray and microwave), irradiation dose, irradiation time and atmosphere etc. on molecular structure of polyolefine during irradiation was studied. The basic rules of dominating oxidation, degradation and cross-linking reactions were mastered. Under the controlled conditions, cross-linking reactions are prevented, some oxygen containing groups are introduced on the molecular chain of polyolefine to facilitate the interface compatibility of their blends. A series of high performance polymer materials: u-HDPE/PA6,u-HDPE/CaCO3, u-iPP/STC, γ-HDPE/STC, γ-LLDPE/ATH, e-HDPE, e-LLDPE and m-HDPEfilled system were prepared (u- ultraviolet light irradiated, γ- γ-ray irradiated, e- electron beam irradiated, m- microwave irradiated)2. The effect of ultrasonic irradiation, jet and pan-milling on structure and changes in properties of polymers were studied. Imposition of critical stress on polymer chain can cause the scission of bonds to form macroradicals. The macroradicals formed in this way may recombine or react with monomer or other radicals to form linear, branched or cross-linked polymers or copolymers. About 20 kinds of block/graft copolymers have been synthesized from polymer-polymer or polymer-monomer through ultrasonic irradiation.Through jet-milling, the molecular weight of PVC is decreased somewhat, the intensity of its crystalline absorption bonds becomes indistinct. The processability, the yield strength, strength at break and elongation at break of PVC get increased quite a lot after

  5. Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Baoxia [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Huang, Yankai [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhu, Xu; Hao, Yuanqiang [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Ding, Yujie [College of Biochemical Engineering, Anhui Polytechnic University, Wuhu 241000 (China); Wei, Wei; Wang, Qi [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Qu, Peng, E-mail: qupeng0212@163.com [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xu, Maotian, E-mail: xumaotian@sqnc.edu.cn [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2016-03-17

    Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg{sup 2+} detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb{sup 3+} from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg{sup 2+} into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg{sup 2+}. As a kind of Hg{sup 2+} nanosensor, the probe exhibited excellent selectivity for Hg{sup 2+} and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg{sup 2+} in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging. - Highlights: • Lanthanide coordination polymer of Tb-CIP/AMP was synthesized via a simple self-assembly process. • AMP was employed as a bifunctional molecule for both fluorescence sensitization and target recognition. • Hypersensitive detection of Hg{sup 2+} was achieved based on time-resolved spectroscopy.

  6. Experimental analysis on the coupled effect between thermo-optical properties and microstructure of semi-crystalline thermoplastics

    Science.gov (United States)

    Boztepe, Sinan; Thiam, Abdoulahad; de Almeida, Olivier; Le Maoult, Yannick; Schmidt, Fabrice

    2016-10-01

    Radiation heat transfer is the most common method used in thermoforming processes of thermoplastic polymers due to their poor thermal conductivity. Considering the fact that the thermo-optical characteristics of polymers play a major role in the efficiency of radiative heat transfer in bulk polymers, microstructure of semi-crystalline thermoplastics is one of the key factors to understand this heat transfer phenomenon in depth. In this study, a relation between the microcrystalline structure of polyolefin (PO) and its effect on the thermo-optical properties was experimentally analyzed. Information on the microcrystalline structure of the samples was obtained by determining the degree of crystallinity (Xc) thanks to Differential Scanning Calorimetry (DSC). Using Fourier Transform Infrared (FT-IR) spectroscopy and integrating sphere, optical characteristics of the PO samples were analyzed considering two spectrums that are in near-infrared (NIR) and middle-infrared (MIR) spectral regions respectively. The analyses showed that the degree of crystallinity has a great effect on the thermo-optical characteristics of the PO - particularly considering transmission - in NIR range. Such a coupled effect can be functionalized and adopted to develop an advanced radiative heat transfer model that may be used for addressing various problems on infrared (IR) heating of heterogeneous materials, particularly semi-crystalline thermoplastics. In the last part of the paper, a theoretical approach for consideration of the heterogeneity of semi-crystalline thermoplastics in a radiative heat transfer model was highlighted.

  7. Efectos de la calidad de la caña semilla en los componentes del rendimiento cultural de las variedades CP65-357 y LCP85-384 (Saccharum spp. según diferentes edades de corte (Parte I Effects of seedcane quality on yielding components of varieties CP65-357 and LCP85-384 (Saccharum spp. in different crops (Part I

    Directory of Open Access Journals (Sweden)

    María I. Cuenya

    2007-06-01

    Full Text Available Las principales variedades de caña de azúcar cultivadas en Tucumán mostraron, hasta hace pocos años, una elevada infección con achaparramiento de la caña soca, enfermedad sistémica causada por Leifsonia xyli subsp. xyli, ampliamente reconocida por su efecto detrimental sobre el rendimiento cultural. Esta situación fue consecuencia de que los productores cañeros utilizaban caña semilla proveniente de lotes comerciales en lugar de caña semilla de semilleros saneados. El objetivo del presente trabajo fue evaluar el efecto de la calidad de la semilla en los componentes del rendimiento cultural en LCP85-384 y CP65-357, dos variedades ampliamente difundidas en Tucumán. Para cada variedad se evaluaron dos alternativas con respecto a la calidad de la semilla: Semilla de Alta Calidad (SAC proveniente de micropropagación in vitro y Semilla Comercial (SC proveniente de un cañaveral comercial. Se implantó un ensayo de acuerdo a un diseño en bloques completos al azar con seis repeticiones. En caña planta, soca 1 y soca 2 se evaluaron: número de tallos/parcela, peso, altura y diámetro del tallo y rendimiento de caña/ha. Se efectuaron análisis de la varianza y pruebas de comparación de medias (DLS de Fisher. En ambas variedades los componentes del rendimiento cultural más afectados por la calidad de la semilla utilizada fueron el peso y la altura de tallos a través de edades de corte. Para CP65-357 y LCP85-384 los tratamientos con SAC produjeron, en promedio, tallos más altos y más pesados en comparación con los tratamientos obtenidos a partir de SC. El diámetro de tallos no se afectó por la calidad de la semilla. Se detectaron importantes disminuciones en el rendimiento cultural (t caña/ha por la utilización de SC (10-25% en CP65-357 y 19-25% en LCP85-384 a través de las edades de corte. Estos resultados sustentan la utilización generalizada de semilleros saneados, sistema puesto en marcha por la EEAOC a partir del año 2000

  8. Development of novel graphene and carbon nanotubes based multifunctional polymer matrix composites

    Science.gov (United States)

    Leung, S. N.; Khan, M. O.; Naguib, H. E.

    2014-05-01

    This paper investigates strategies to alter the nano-and-microstructures of carbon-based filler-reinforced polymer matrix composites (PMCs). The matrix materials being studied in this work include polyphenylene sulfide (PPS) and liquid crystal polymer (LCP). A set of experiments were performed to investigate various strategies (i) to fabricate a morphological structure within the polymer matrix; (ii) to develop a thermally and electrically conductive network of nano-scaled fillers; and (iii) to produce a thermally conductive but electrically insulative network of hybrid fillers of nano-and-micro scales. The PMCs' structure-to-property relationships, including electrical and thermal properties, were revealed. In particular, the composites' effective thermal conductivities could be increased by as much as 10-folded over the neat polymers. By structuring the embedded electrically conductive pathways in the PMCs, their electrical conductivities could be tailored to levels that ranged from those of electrical insulators to those of semi-conductors. These multifunctional carbon-based filler-reinforced PMCs are envisioned to be potential solutions of various engineering problems. For example, light-weight thermally conductive PMCs with tailored electrical conductivities can serve as a new family of materials for electronic packaging or heat management applications.

  9. SYNTHESIS OF NOVEL LIQUID CRYSTALLINE POLY(METH)ACRYLATES CONTAINING SILOXANE SPACER AND TERPHENYLENE MESOGENIC UNIT

    Institute of Scientific and Technical Information of China (English)

    Zhi-qian Zang; Yu-fei Luo; Dong Zhang; Xin-hua Wan; Qi-feng Zhou

    2000-01-01

    Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized using 1-(3-hydroxyl-propyl)-3-[(4"cyano-p-terphenyloxycarbonyl)alkyl]-1, 1,3,3-tetramethyldisiloxane as the key intermediate. The polymers used a disiloxane moiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC,DSC and polarizing optical microscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase.However, if the mesogenic unit is replaced by cyano-p-biphenyl, the liquid crystalline character will be lost. The results also showed that the decoupling is incomplete even if a complex and very flexible decoupling spacer is deliberately incorporated to obtain the highest possible decoupling effect.

  10. Crystallinity evaluation of polyhydroxybutyrate and polycaprolactone blends; Avaliacao da cristalinidade de blendas de polihidroxibutirato e policaprolactona

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcante, Maxwell P.; Rodrigues, Elton Jorge R.; Tavares, Maria Ines B., E-mail: maxdpc@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Instituto de Macromoleculas

    2015-07-01

    Polyhydroxybutyrate, PHB, is a polymer obtained through bacterial or synthetic pathways. It has been used in the biomedical field as a matrix for drug delivery, medical implants and as scaffold material for tissue engineering. PHB has high structural organization, which makes it highly crystalline and brittle, making biodegradation difficult, reducing its employability. In order to enhance the mechanical and biological properties of PHB, blends with other polymers, biocompatible or not, are researched and produced. In this regard, blends of PHB and polycaprolactone, PCL, another biopolymer widely used in the biomedical industry, were obtained via solution casting and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and low field nuclear magnetic resonance (LF-NMR). Results have shown a dependence between PHB's crystallinity index and PCL quantity employed to obtain the blends.(author)

  11. Free-surface molecular command systems for photoalignment of liquid crystalline materials.

    Science.gov (United States)

    Fukuhara, Kei; Nagano, Shusaku; Hara, Mitsuo; Seki, Takahiro

    2014-01-01

    The orientation of liquid crystal molecules is very sensitive towards contacting surfaces, and this phenomenon is critical during the fabrication of liquid crystal display panels, as well as optical and memory devices. To date, research has focused on designing and modifying solid surfaces. Here we report an approach to control the orientation of liquid crystals from the free (air) surface side: a skin layer at the free surface was prepared using a non-photoresponsive liquid crystalline polymer film by surface segregation or inkjet printing an azobenzene-containing liquid crystalline block copolymer. Both planar-planar and homoeotropic-planar mode patterns were readily generated. This strategy is applicable to various substrate systems, including inorganic substrates and flexible polymer films. These versatile processes require no modification of the substrate surface and are therefore expected to provide new opportunities for the fabrication of optical and mechanical devices based on liquid crystal alignment.

  12. Semiconducting polymer single crystals and devices (Conference Presentation)

    Science.gov (United States)

    Dong, Huanli

    2016-11-01

    Highly ordered organic semiconductors in solid state with optimal molecular packing are critical to their electrical performance. Single crystals with long-range molecular orders and nearly perfect molecular packing are the best candidates, which already have been verified to exhibit the highest performance whether based on inorganic or small organic materials. However, in comparison, preparing high quality polymer crystals remains a big challenge in polymer science because of the easy entanglements of the long and flexible polymer chains during self-assembly process, which also significantly limits the development of their crystalline polymeric electronic devices. Here we have carried out systematical investigations to prepare high quality semiconducting polymers and high performance semiconducting polymer crystal optoelectronic devices have been successfully fabricated. The semiconducting polymeric devices demonstrate significantly enhanced charge carreir transport compared to their thin films, and the highest carreir mobiltiy could be approcahing 30 cm2 V-1s-1, one of the highest mobiltiy values for polymer semiconductors.

  13. Antimocrobial Polymer

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, William F. (Utica, OH); Huang, Zhi-Heng (Walnut Creek, CA); Wright, Stacy C. (Columbus, GA)

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  14. Polymer inflation

    CERN Document Server

    Hassan, Syed Moeez; Seahra, Sanjeev S

    2014-01-01

    We consider the semi-classical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a gaussian coherent state. For quadratic potentials, the semi-classical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by a epoch of slow-roll inflation. We compute polymer corrections to the slow roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  15. Topochemical control in desolvation of coordination polymers

    OpenAIRE

    Matteo Lusi

    2015-01-01

    Reactions in the solid state are at the core of crystal engineering as they can result in new crystalline phases that are not always accessible by traditional solution methods. The work of Brammer and co-workers [Wright et al. (2015), IUCrJ, 2, 188–197] represents a clear example of this potential as applied to the synthesis of a silver–phenazine coordination polymer.

  16. Birefringence Measurements on Crystalline Silicon

    CERN Document Server

    Krüger, Christoph; Khalaidovski, Alexander; Steinlechner, Jessica; Nawrodt, Ronny; Schnabel, Roman; Lück, Harald

    2015-01-01

    Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein Telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarisation-dependent resonance frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of $\\Delta\\, n \\approx 10^{-7}$ at a laser wavelength of 1550nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

  17. Polymer electronics

    CERN Document Server

    Geoghegan, Mark

    2013-01-01

    Polymer electronics is the science behind many important new developments in technology, such as the flexible electronic display (e-ink) and many new developments in transistor technology. Solar cells, light-emitting diodes, and transistors are all areas where plastic electronics is likely to, or is already having, a serious impact on our daily lives. With polymer transistors and light-emitting diodes now being commercialised, there is a clear need for a pedagogic text thatdiscusses the subject in a clear and concise fashion suitable for senior undergraduate and graduate students. The content

  18. Oxygen plasma etching-induced crystalline lattice transformation of colloidal photonic crystals.

    Science.gov (United States)

    Ding, Tao; Wang, Fei; Song, Kai; Yang, Guoqiang; Tung, Chen-Ho

    2010-12-15

    This communication describes the transformation of a colloidal crystalline lattice that was realized via oxygen plasma etching of colloidal crystals made of SiO2@PMMA core-shell microspheres. The plasma etching of the colloidal crystals proceeded nonuniformly from the top to the bottom of the colloidal crystals. The PMMA shell was etched away by the oxygen plasma in a layer-by-layer manner, and the silica core was drawn into the pit formed by the neighboring spheres in the layer below. Consequently, the crystalline lattice was transformed while the order was maintained. Scanning electron microscopy images and reflection spectra further confirmed the change in the crystalline structures. Colloidal crystals with sc and bcc lattices can be fabricated if the ratio of the polymer shell thickness to the silica core diameter is equal to certain values. More importantly, this approach may be applicable to the fabrication of various assembly structures with different inorganic particles.

  19. Structural phase study in un-patterned and patterned PVDF semi-crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Pramod, K., E-mail: rameshg.phy@pondiuni.edu.in; Gangineni, Ramesh Babu, E-mail: rameshg.phy@pondiuni.edu.in [Department of Physics, Pondicherry University, R. V. Nagar, Kalapet, Puducherry - 605014 (India)

    2014-04-24

    This work explores the structural phase studies of organic polymer- polyvinylidene fluoride (PVDF) thin films in semi-crystallized phase and nano-patterned PVDF thin films. The nanopatterns are transferred with the CD layer as a master using soft lithography technique. The semi-crystalline PVDF films were prepared by a still and hot (SH) method, using a homemade spin coater that has the proficiency of substrate heating by a halogen lamp. Using this set up, smooth PVDF thin films in semi-crystalline α-phase were prepared using 2-Butanone as solvent. XRD, AFM and confocal Raman microscope have been utilized to study the structural phase, crystallinity and quality of the films.

  20. Enhancement in Mechanical and Shape Memory Properties for Liquid Crystalline Polyurethane Strengthened by Graphene Oxide

    OpenAIRE

    Yueting Li; Huiqin Lian; Yanou Hu; Wei Chang; Xiuguo Cui; Yang Liu

    2016-01-01

    Conventional shape memory polymers suffer the drawbacks of low thermal stability, low strength, and low shape recovery speed. In this study, main-chain liquid crystalline polyurethane (LCPU) that contains polar groups was synthesized. Graphene oxide (GO)/LCPU composite was fabricated using the solution casting method. The tensile strength of GO/LCPU was 1.78 times that of neat LCPU. In addition, shape recovery speed was extensively improved. The average recovery rate of sample with 20 wt % GO...

  1. Preparation and characterization of new poly-pyrrole having side chain liquid crystalline moieties

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, S. Hossein, E-mail: hosseini_sh44@yahoo.com [Department of Chemistry, Faculty of Science and Engineering, Imam Hossein University, Babaee Express Way, Tehran (Iran, Islamic Republic of); Mohammadi, M. [Department of Chemistry, Faculty of Science and Engineering, Imam Hossein University, Babaee Express Way, Tehran (Iran, Islamic Republic of)

    2009-06-01

    We have synthesized a novel liquid-crystalline (LC)-conducting polymer by introducing LC group into pyrrole monomer and polymerizing it with FeCl{sub 3}. The N-substituted pyrrole with LC group (Py-RedII) was prepared by direct reaction of potassium pyrrole salt with 2-[N-ethyl-N-[4-[(4-nitrophenyl)azo]-phenyl]amino]ethyl-3-chloropropionate (RedII). The polymerization of this monomer was successful, giving a conjugated polymer system with liquid crystalline moieties in moderate yield. The polymer obtained was soluble in organic solvents and had a thermotropic liquid crystallinity with mosaic texture characterized by polarizing optical microscopy. Phase transitions, thermal analysis and rheological studies were also evaluated by means of differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM), respectively. Spectral properties of poly (2-[N-ethyl-N-[4-[(nitrophenyl)azo]phenyl]amino]ethyl-N-pyrrolyl propionate) (PPy-RedII) were characterized by UV, IR, {sup 1}H NMR, and {sup 13}C NMR spectroscopies. The photoluminescence spectrum of the film showed that maximum photoluminescence peak emission is located at 437 nm, corresponding to the photon energy of 2.5 eV. Electrical conductivity of PPy-RedII was studied by the four-probe method and produced a conductivity of 7.5 x 10{sup -4} S cm{sup -1}.

  2. Picosecond laser ablation of poly-L-lactide: Effect of crystallinity on the material response

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Rocio; Quintana, Iban; Etxarri, Jon [Manufacturing Processes Department, Fundacion TEKNIKER, Av. Otaola 20, 20600, Eibar, Guipuzcoa (Spain); Lejardi, Ainhoa; Sarasua, Jose-Ramon [Department of Mining and Metallurgy Engineering and Materials Science, School of Engineering, University of the Basque Country (EHU-UPV), Alameda de Urquijo s/n, 48013 Bilbao (Spain)

    2011-11-01

    The picosecond laser ablation of poly-L-lactide (PLLA) as a function of laser fluence and degree of crystallinity was examined. The ablation parameters and the surface modifications were analyzed under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible. When processing the amorphous PLLA, both energy threshold and topography varied considerably depending on laser wavelength. Laser irradiation showed a reduction in the energy ablation threshold as the degree of crystallinity increased, probably related to photomechanical effects involved in laser ablation with ultra-short pulses and the lower stress accommodation behavior of semicrystalline polymers. In particular, cooperative chain motions are impeded by the higher degree of crystallinity, showing fragile mechanical behavior and lower energy dissipation. The experimental results on ablation rate versus laser energy showed that UV laser ablation on semicrystalline PLLA was more efficient than the visible ablation, i.e., it exhibits higher etch rates over a wide range of pulse energy conditions. These results were interpreted in terms of photo-thermal and photo-chemical response of polymers as a function of material micro-structure and incident laser wavelength. High quality micro-grooves were produced in amorphous PLLA, reveling the potential of ultra-fast laser processing technique in the field of micro-structuring biocompatible and biodegradable polymers for biomedical applications.

  3. Antimicrobial polymers.

    Science.gov (United States)

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed.

  4. Polymer physics

    CERN Document Server

    Gedde, Ulf W

    1999-01-01

    This book is the result of my teaching efforts during the last ten years at the Royal Institute of Technology. The purpose is to present the subject of polymer physics for undergraduate and graduate students, to focus the fundamental aspects of the subject and to show the link between experiments and theory. The intention is not to present a compilation of the currently available literature on the subject. Very few reference citations have thus been made. Each chapter has essentially the same structure: starling with an introduction, continuing with the actual subject, summarizing the chapter in 30D-500 words, and finally presenting problems and a list of relevant references for the reader. The solutions to the problems presented in Chapters 1-12 are given in Chapter 13. The theme of the book is essentially polymer science, with the exclusion of that part dealing directly with chemical reactions. The fundamentals in polymer science, including some basic polymer chemistry, are presented as an introduction in t...

  5. Radiation induced crystallinity damage in poly(L-lactic acid)

    CERN Document Server

    Kantoglu, O

    2002-01-01

    The radiation-induced crystallinity damage in poly(L-lactic acid) (PLLA) in the presence of air and in vacuum, is studied. From the heat of fusion enthalpy values of gamma irradiated samples, some changes on the thermal properties were determined. To identify these changes, first the glass transition temperature (T sub g) of L-lactic acid polymers irradiated to various doses in air and vacuum have been investigated and it is found that it is independent of irradiation atmosphere and dose. The fraction of damaged units of PLLA per unit of absorbed energy has been measured. For this purpose, SAXS and differential scanning calorimetry methods were used, and the radiation yield of number of damaged units (G(-u)) is found to be 0.74 and 0.58 for PLLA samples irradiated in vacuum and air, respectively.

  6. STUDIES ON CRITICAL CONCENTRATION OF LIQUID CRYSTALLINE ETHYLCELLULOSE

    Institute of Scientific and Technical Information of China (English)

    DONG Yanming; ZHANG Shiying

    1996-01-01

    Critical concentrations of lyotropic liquid crystalline ethylcellulose in more than ten cal concentration Ccrit of forming liquid crystal phase decreased with increasing solubility parameter δ of solvent until approaching the δ of polymer. Although the alcohols used as solvents had the same variation rule, the critical concentration values of their solutions were much higher, due to their excessive large hydrogen bond component of δ. The experiments of using mixed solvents which showed good linear relation between Ccrit and δ also proved this rule. A technique of Transmission Optical Analysis was first used to estimate the concentration dependence of critical phase transition temperature Tcrit of EC, and a T-C phase diagram could be drawn.

  7. SYNTHESIS OF A NOVEL "MESOGEN-JACKETED LIQUID CRYSTAL POLYMER" BASED ON VINYLTEREPHTHALIC ACID

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Poly{2, 5-bis[(p-methoxyphenyl)oxycarbonyl]styrene} was successfully synthesized. This new polymer has a structure characteristic of mesogen-jacketed liquid cyrstalline polymers (MJLCPs) and does form a liquid crystal phase above its glass transition. It thus became the starting member of a new series of MJLCPs. The synthesis of the polymer as well as the liquid crystalline properties of the polymer and its monomer was discussed. A brief comparison of the new monomer and polymer with some previously reported counterparts was also included.

  8. Bietti crystalline dystrophy and choroidal neovascularisation.

    Science.gov (United States)

    Gupta, B; Parvizi, S; Mohamed, M D

    2011-02-01

    Bietti crystalline dystrophy is a rare autosomal recessive condition characterised by the presence of crystals in the retina and is followed by retinal and choroidal degeneration. We present a novel finding of juxtafoveal choroidal neovascularisation in Bietti crystalline dystrophy and demonstrate a spectral domain optical coherence tomography image of this disorder.

  9. Structure and Morphology Control in Thin Films of Conjugated Polymers for an Improved Charge Transport

    OpenAIRE

    Haiyang Wang; Yaozhuo Xu; Xinhong Yu; Rubo Xing; Jiangang Liu; Yanchun Han

    2013-01-01

    The morphological and structural features of the conjugated polymer films play an important role in the charge transport and the final performance of organic optoelectronics devices [such as organic thin-film transistor (OTFT) and organic photovoltaic cell (OPV), etc.] in terms of crystallinity, packing of polymer chains and connection between crystal domains. This review will discuss how the conjugated polymer solidify into, for instance, thin-film structures, and how to control the molecula...

  10. Structure and Morphology Control in Thin Films of Conjugated Polymers for an Improved Charge Transport

    OpenAIRE

    Haiyang Wang; Yaozhuo Xu; Xinhong Yu; Rubo Xing; Jiangang Liu; Yanchun Han

    2013-01-01

    The morphological and structural features of the conjugated polymer films play an important role in the charge transport and the final performance of organic optoelectronics devices [such as organic thin-film transistor (OTFT) and organic photovoltaic cell (OPV), etc.] in terms of crystallinity, packing of polymer chains and connection between crystal domains. This review will discuss how the conjugated polymer solidify into, for instance, thin-film structures, and how to control the molecula...

  11. Solid Polymer Electrolytes Based on Cross-linkable Oligo (oxyethylene)-Branched Oligo (organophosphazenes)

    Institute of Scientific and Technical Information of China (English)

    Shuhua Zhou; Shibi Fang

    2005-01-01

    @@ 1Introduction Solid polymer electrolytes have attracted considerable interest because of their potential application in secondary high energy density lithium batteries. The poly(ethylene oxide)(PEO) has been widely studied as the classical polymer matrix for solid polymer electrolytes. However, the poor room temperature conductivity due to its crystalline is the principal problem to be overcomed. This has prompted many researchers to attempt to modify the properties of PEO.

  12. Heavy ion irradiation of crystalline water ice

    CERN Document Server

    Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C

    2015-01-01

    Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...

  13. Impact of crystalline quality on neuronal affinity of pristine graphene.

    Science.gov (United States)

    Veliev, Farida; Briançon-Marjollet, Anne; Bouchiat, Vincent; Delacour, Cécile

    2016-04-01

    Due to its outstanding mechanical and electrical properties as well as chemical inertness, graphene has attracted a growing interest in the field of bioelectric interfacing. Herein, we investigate the suitability of pristine, i.e. without a cell adhesive coating, chemical vapor deposition (CVD) grown monolayer graphene to act as a platform for neuronal growth. We study the development of primary hippocampal neurons grown on bare graphene (transferred on glass coverslip) for up to 5 days and show that pristine graphene significantly improves the neurons adhesion and outgrowth at the early stage of culture (1-2 days in vitro). At the later development stage, neurons grown on coating free graphene (untreated with poly-L-lysine) show remarkably well developed neuritic architecture similar to those cultured on conventional poly-L-lysine coated glass coverslips. This exceptional possibility to bypass the adhesive coating allows a direct electrical contact of graphene to the cells and reveals its great potential for chronic medical implants and tissue engineering. Moreover, regarding the controversial results obtained on the neuronal affinity of pristine graphene and its ability to support neuronal growth without the need of polymer or protein coating, we found that the crystallinity of CVD grown graphene plays an important role in neuronal attachment, outgrowth and axonal specification. In particular, we show that the decreasing crystalline quality of graphene tunes the neuronal affinity from highly adhesive to fully repellent.

  14. STRUCTURE EVOLUTION OF POLYMER CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

    Institute of Scientific and Technical Information of China (English)

    Hong Zheng; Wei Yu; Hong-bin Zhang; Chi-xing Zhou

    2006-01-01

    Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions. The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.

  15. New anterolateral LCP for internal fixation of pilon fractures%新型胫骨远端前外侧锁定加压钢板用于Pilon骨折内固定

    Institute of Scientific and Technical Information of China (English)

    史德海; 卢华定; 李东会; 蔡道章

    2010-01-01

    Objective To introduce experience of using the new AO anterolateral distal tibia locking com-pression plate (LCP) for treatment of Pilon fractures. Methods Between February and August of 2009,8 closed Pi-lon fractures were treated by open reduction and internal fixation. The distal fibula was fixed with a one-third tubular plate or an recontruction plate via a straight incision posterior to the fibular crest. The distal tibia was approched by a straight incision over the ankle joint, and the fracture was stabilized using an anterolateral distal tibia LCP. Regular follow up was made to observe and evaluate the preliminary clinical outcomes. Results Seven of the 8 patients were availabe for follow up for 3 ~ 6 months (average 4.5 months). All incisions obtained primary healing, though one ex-perienced mild superficial inflammation,and none developed deep infections. Based on the Burwell and Charnley radi-ographic criteria,anatomical reduction was obtained in 5 cases,good in 1 ,and fair in 1. Among the 5 cases exceeding 5 months postsurgery,4 were evaluated as excellent and 1 us good according to Tometta' s clinically based criteria for Pilon fractures. Conclusion With good surgical timing,internal fixation with anterolateral LCP for Pilon fractures is reliable and warrants less complications.%目的 介绍新型AO胫骨远端前外侧锁定加压钢板(IEP)治疗胫骨远端骨折(Pilon骨折)的初步经验.方法 手术治疗8例闭合性Pilon骨折,腓骨作外踝后方纵切口,复位后用1/3管形或重建钢板固定;胫骨远端骨折采用踝关节前方中点纵向直切口,复位后采用胫骨远端前外侧LCP内固定,术后进行定期临床随访.观察初步疗效.结果 术后7例患者获得随访3~6个月(平均4.5个月).虽有1例切口出现短暂的表浅轻微炎症,最终所有切口均一期愈合,无深部感染发生.按照Burwell-Charnley骨折复位放射学评价标准,解剖复位5例,1例复位好,1例可;采用Tometta治

  16. Diketopyrrolopyrrole Polymers for Organic Solar Cells.

    Science.gov (United States)

    Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

    2016-01-19

    Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with

  17. Diffusion in porous crystalline materials.

    Science.gov (United States)

    Krishna, Rajamani

    2012-04-21

    The design and development of many separation and catalytic process technologies require a proper quantitative description of diffusion of mixtures of guest molecules within porous crystalline materials. This tutorial review presents a unified, phenomenological description of diffusion inside meso- and micro-porous structures. In meso-porous materials, with pore sizes 2 nm < d(p) < 50 nm, there is a central core region where the influence of interactions of the molecules with the pore wall is either small or negligible; meso-pore diffusion is governed by a combination of molecule-molecule and molecule-pore wall interactions. Within micro-pores, with d(p) < 2 nm, the guest molecules are always under the influence of the force field exerted with the wall and we have to reckon with the motion of adsorbed molecules, and there is no "bulk" fluid region. The characteristics and physical significance of the self-, Maxwell-Stefan, and Fick diffusivities are explained with the aid of data obtained either from experiments or molecular dynamics simulations, for a wide variety of structures with different pore sizes and topology. The influence of adsorption thermodynamics, molecular clustering, and segregation on both magnitudes and concentration dependences of the diffusivities is highlighted. In mixture diffusion, correlations in molecular hops have the effect of slowing-down the more mobile species. The need for proper modeling of correlation effects using the Maxwell-Stefan formulation is stressed with the aid of examples of membrane separations and catalytic reactors.

  18. Donor polymer design enables efficient non-fullerene organic solar cells.

    Science.gov (United States)

    Li, Zhengke; Jiang, Kui; Yang, Guofang; Lai, Joshua Yuk Lin; Ma, Tingxuan; Zhao, Jingbo; Ma, Wei; Yan, He

    2016-10-26

    To achieve efficient organic solar cells, the design of suitable donor-acceptor couples is crucially important. State-of-the-art donor polymers used in fullerene cells may not perform well when they are combined with non-fullerene acceptors, thus new donor polymers need to be developed. Here we report non-fullerene organic solar cells with efficiencies up to 10.9%, enabled by a novel donor polymer that exhibits strong temperature-dependent aggregation but with intentionally reduced polymer crystallinity due to the introduction of a less symmetric monomer unit. Our comparative study shows that an analogue polymer with a C2 symmetric monomer unit yields highly crystalline polymer films but less efficient non-fullerene cells. Based on a monomer with a mirror symmetry, our best donor polymer exhibits reduced crystallinity, yet such a polymer matches better with small molecular acceptors. This study provides important insights to the design of donor polymers for non-fullerene organic solar cells.

  19. Donor polymer design enables efficient non-fullerene organic solar cells

    Science.gov (United States)

    Li, Zhengke; Jiang, Kui; Yang, Guofang; Lai, Joshua Yuk Lin; Ma, Tingxuan; Zhao, Jingbo; Ma, Wei; Yan, He

    2016-10-01

    To achieve efficient organic solar cells, the design of suitable donor-acceptor couples is crucially important. State-of-the-art donor polymers used in fullerene cells may not perform well when they are combined with non-fullerene acceptors, thus new donor polymers need to be developed. Here we report non-fullerene organic solar cells with efficiencies up to 10.9%, enabled by a novel donor polymer that exhibits strong temperature-dependent aggregation but with intentionally reduced polymer crystallinity due to the introduction of a less symmetric monomer unit. Our comparative study shows that an analogue polymer with a C2 symmetric monomer unit yields highly crystalline polymer films but less efficient non-fullerene cells. Based on a monomer with a mirror symmetry, our best donor polymer exhibits reduced crystallinity, yet such a polymer matches better with small molecular acceptors. This study provides important insights to the design of donor polymers for non-fullerene organic solar cells.

  20. Femoral Locking Compression Plate (LCP)for the Subtrochanteric Fractures in Children%股骨锁定加压钢板(LCP)在儿童股骨转子下骨折中的应用

    Institute of Scientific and Technical Information of China (English)

    蔡文全; 覃佳强; 南国新; 王忠良; 宿玉玺; 张德文

    2014-01-01

    Objetive To study the clinical effect of the femoral locking compression plate (LCP)in children femoral subtrochanteric fracture. Methods 22 cases of femoral subtrochanteric fracture in children diagnosed in our hospital from February 201 0 to December 201 2 were analyzed retrospectively,including 1 6 ca-ses of male,6 cases of female,with an average age of 8.5.Results All of the 22 cases received follow-ups ranging from 6 to 48 months (27 months in average);osseous healing was found in all these 22 cases of frac-ture,without broken nails,nail,loose steel plate,broken board or coax vara,articular dyskinesia,etc. Con-clusion Application of femoral locking compression plate (LCP)for children femoral subtrochanteric fractures can effectively improve the deficiencies of the traditional conservative treatments including traction,k-wire,ti-tanium elastic nail fixation and other therapies,and can achieve a better effect through early functional exercise to reduce joint rigidity.%目的:探讨股骨锁定加压钢板(LCP)对儿童股骨转子下骨折的临床疗效。方法回顾性分析本院2010年2月至2012年12月收治的22例股骨转子下骨折患儿临床资料,其中男16例,女6例,平均年龄8.5岁。结果22例均获得随访,随访时间6~48个月,平均27个月,22例均骨性愈合,无断钉、脱钉、钢板松动、断板及髋内翻、关节活动障碍等并发症发生。结论股骨锁定加压钢板(LCP)对于儿童股骨转子下骨折可以有效改善传统保守牵引、克式针、弹性髓内钉固定及其他治疗方法的不足,可早期进行功能锻炼,减少关节僵直,效果良好。

  1. Cellulose Acetate Sulfate as a Lyotropic Liquid Crystalline Polyelectrolyte: Synthesis, Properties, and Application

    Directory of Open Access Journals (Sweden)

    D. D. Grinshpan

    2010-01-01

    Full Text Available The optimal conditions of cellulose acetate sulfate (CAS homogeneous synthesis with the yield of 94–98 wt.% have been determined. CAS was confirmed to have an even distribution of functional groups along the polymer chain. The polymer was characterized by an exceptionally high water solubility (up to 70 wt.%. The isothermal diagrams of its solubility in water-alcohol media have been obtained. CAS aqueous solutions stability, electrolytic, thermal, and viscous properties have been defined. The main hydrodynamic characteristics such as intrinsic viscosity, Huggins constant, and crossover concentration have been evaluated. The parameters of polymer chain thermodynamic rigidity have been calculated. The formation of liquid crystalline structures in concentrated CAS solutions has been confirmed. CAS was recommended to be used as a binder for the medicinal forms of activated carbon and carbon sorbent for water treatment, hydrophilic ointment foundation.

  2. Fullerene-based one-dimensional crystalline nanopolymer formed through topochemical transformation of the parent nanowire

    DEFF Research Database (Denmark)

    Geng, Junfeng; Solov'yov, Ilia; Reid, David G.;

    2010-01-01

    Large-scale practical applications of fullerene (C_60) in nanodevices could be significantly facilitated if the commercially available micrometer-scale raw C_60 powder were further processed into a one-dimensional nanowire-related polymer displaying covalent bonding as molecular interlinks...... and resembling traditional important conjugated polymers. However, there has been little study thus far in this area despite the abundant literature on fullerene. Here we report the preparation and characterization of such a C_60-based polymer nanowire, (-C_60.TMB-)_n, where TMB=1,2,4-trimethylbenzene, which...... displays a well-defined crystalline nanostructure, exceptionally large length-to-width ratio and excellent thermal stability. The material is prepared by first growing the corresponding nanowire through a solution phase of C_60 followed by a topochemical polymerization reaction in the solid state. Gas...

  3. Transfer Printed Crystalline Nanomembrane for Versatile Electronic Applications

    Science.gov (United States)

    Seo, Jung-Hun

    Flexible electronics have traditionally been addressed low-frequency applications, since the materials for the traditional flexible electronics, such as polymer and non-crystalline inorganic semiconductors, have poor electronic properties. Fast flexible electronics that operate at radio frequencies (RF), particularly at microwave frequencies, could lead to a number of novel RF applications where rigid chip-based solid-state electronics cannot easily fulfill. Single-crystal semiconductor nanomembranes (NM) that can be released from a number of wafer sources are mechanically very flexible yet exhibit outstanding electronic properties that are equivalent to their bulky counterparts. These thin flexible single-crystal materials can furthermore be placed, via transfer printing techniques, to nearly any substrate, including flexible polymers, thus creating the opportunity to realize RF flexible electronics. In this thesis, various RF transistors made of semiconductor NMs on plastic substrates will be discussed. In addition, as a photonic application, the demonstration of large-area Si NM surface normal ultra-compact photonic crystal reflectors fabricated using the laser interference lithography technique (LIL) will be discussed. Particularly, the mechanism of LIL and NM transfer without using an adhesive layer will be introduced and their optical performance will be addressed. Lastly, the realization of selective substitutional boron doping, using heavily doped Si NM as a doping source, will be discussed. A detailed mechanism using computational modeling and experimental analyses will be provided. The fabrication of high voltage diamond p-i diodes and their performance will be discussed.

  4. History of crystalline organic conductor

    Science.gov (United States)

    Murata, Keizo

    2017-05-01

    A brief view of crystalline organic conductor is presented. Since the discovery of TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) in the mid 1970’s, pressure has been an indispensable tool to develop the physics of this field. From the aspect of charge transfer salt, TTF-TCNQ and its family was specified with partial charge transfer, two chain one-dimensional (1D) system, charge density wave (CDW) and commensurability. On the other hand, in (TMTSF)2X family (TMTSF: tetramethyltetraselenafulvalene, X: electron acceptor such as PF6, ClO4), complete charge transfer, one chain system, spin density wave (SDW), field-induced SDW, quantum Hall effect, superconductivity were discussed. Further, together with pressure itself, cooling rate was noticed to be important for low temperature properties. Recently, coming back to TTF-TCNQ family, i.e., HMTSF-TCNQ, whether or not field-induced CDW, instead of field-induced SDW, and quantum Hall effect is present was discussed (HMTSF: hexamethylene-tetraselenafulvalene). Whether or not the Fermiology in (TMTTF)2X under pressure is similar to that of (TMTSF)2X is discussed as well. In (BEDT-TTF)2X, new aspect of macroscopic polarization of α-(BEDT-TTF)2I3 related to charge order is described. At the end, in contrast to the charge transfer salts, non-charge transfer salt, that is, single component conductor is presented as a new possible example of Dirac cone, which was deeply studied by many researchers in α-(BEDT-TTF)2I3, together with the theoretical calculation of its magnetic susceptibility (BEDT-TTF: bisethylenedithia-tetrathiafulvalene).

  5. Isoindigo-based polymer photovoltaics: modifying polymer molecular structures to control the nanostructural packing motif.

    Science.gov (United States)

    Kim, Yu Jin; Lee, Yun-Ji; Kim, Yun-Hi; Park, Chan Eon

    2016-07-21

    Donor molecular structures, and their packing aspects in donor:acceptor active blends, play a crucial role in the photovoltaic performance of polymer solar cells. We systematically investigated a series of isoindigo-based donor polymers within the framework of a three-dimensional (3D) crystalline motif by modifying their chemical structures, thereby affecting device performances. Although our isoindigo-based polymer series contained polymers that differed only by their alkyl side chains and/or donating units, they showed quite different nanoscale morphological properties, which resulted in significantly different device efficiencies. Notably, blends of our isoindigo-based donor polymer systems with an acceptor compound, whereby the blends had more intermixed network morphologies and stronger face-on orientations of the polymer crystallites, provided better-performing photovoltaic devices. This behavior was analyzed using atomic force microscopy (AFM) and two-dimensional grazing incidence wide angle X-ray diffraction (2D-GIWAXD). To the best of our knowledge, no correlation has been reported previously between 3D nano-structural donor crystallites and device performances, particularly for isoindigo-based polymer systems.

  6. Light-induced disorder in liquid-crystalline elastomers for actuation

    Science.gov (United States)

    Sánchez-Ferrer, Antoni

    2011-10-01

    Liquid-Crystalline Elastomers (LCEs) are materials which combine the entropic properties of a crosslinked polymer melt with the enthalpic properties of a liquid-crystalline state of order. LCEs show unique characteristics: visco-elasticity and order at the same time in one system. The elastic and the viscous properties come from the crosslinking and friction of the polymer chains, respectively, while the orientation comes from the mesophase which keeps the polymer backbone aligned. LCEs behave as normal polymer networks or rubbers when no energy-storing mesophase is present. This state of disorder can be induced by means of temperature or light. Thermally, the change in shape of LCEs can easily reach 300% when all the enthalpy stored by the mesophase is released and the crosslinked polymer chains are free to move and adopt a random coil conformation. The light-induced local disorder can be achieved when shape-changing molecules are incorporated in the LCE matrix. These compounds are able to absorb light, rearrange themselves in a new shape and subsequently disturbing the mesophase. This results in the molecules that are keeping the order no longer being able to sustain the retractive force of the polymer backbone, and the material contracts, exerting an actuating force. But how does a light sensitive side-chain LCE elastomer behave? And a main-chain LCE? What about nematics or smectics? Is a different kind of actuation, besides the common retractive force, possible? To answer these questions, new chemistry needs to be developed, together with new physics to understand the systems, and new applications need to be created.

  7. Non-Stoichiometric Polymer-Cyclodextrin Inclusion Compounds: Constraints Placed on Un-Included Chain Portions Tethered at Both Ends and Their Relation to Polymer Brushes

    Directory of Open Access Journals (Sweden)

    Alan E. Tonelli

    2014-08-01

    Full Text Available When non-covalently bonded crystalline inclusion compounds (ICs are formed by threading the host cyclic starches, cyclodextrins (CDs, onto guest polymer chains, and excess polymer is employed, non-stoichiometric (n-s-polymer-CD-ICs, with partially uncovered and “dangling” chains result. The crystalline host CD lattice is stable to ~300 °C, and the uncovered, yet constrained, portions of the guest chains emanating from the CD-IC crystal surfaces behave very distinctly from their neat bulk samples. In CD-IC crystals formed with α- and γ-CD hosts, each containing, respectively, six and eight 1,4-α-linked glucose units, the channels constraining the threaded portions of the guest polymer chains are ~0.5 and 1.0 nm in diameter and are separated by ~1.4 and 1.7 nm. This results in dense brushes with ~0.6 and 0.4 chains/nm2 (or 0.8 if two guest chains are included in each γ-CD channel of the un-included portions of guest polymers emanating from the host CD-IC crystal surfaces. In addition, at least some of the guest chains leaving from a crystalline CD-IC surface re-enter another CD-IC crystal creating a network structure that leads to shape-memory behavior for (n-s-polymer-CD-ICs. To some extent, (n-s-polymer-CD-ICs can be considered as dense polymer brushes with chains that are tethered on both ends. Not surprisingly, the behavior of the un-included portions of the guest polymer chains in (n-s-polymer-CD-ICs are quite different from those of their neat bulk samples, with higher glass-transition and melt crystallization temperatures and crystallinities. Here we additionally compare their behaviors to samples coalesced from their stoichiometric ICs, and more importantly to dense polymer brushes formed by polymer chains chemically bonded to surfaces at only one end. Judging on the basis of their glass-transition, crystallization and melting temperatures, and crystallinities, we generally find the un-included portions of chains in (n-s-polymer

  8. Gas-phase synthesis of magnetic metal/polymer nanocomposites.

    Science.gov (United States)

    Starsich, Fabian H L; Hirt, Ann M; Stark, Wendelin J; Grass, Robert N

    2014-12-19

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

  9. Gas-phase synthesis of magnetic metal/polymer nanocomposites

    Science.gov (United States)

    Starsich, Fabian H. L.; Hirt, Ann M.; Stark, Wendelin J.; Grass, Robert N.

    2014-12-01

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

  10. Synthesis of polymer nanostructures with conductance switching properties

    Energy Technology Data Exchange (ETDEWEB)

    Su, Kai; Nuraje, Nurxat; Zhang, Lingzhi; Matsui, Hiroshi; Yang, Nan Loh

    2015-03-03

    The present invention is directed to crystalline organic polymer nanoparticles comprising a conductive organic polymer; wherein the crystalline organic polymer nanoparticles have a size of from 10 nm to 200 nm and exhibits two current-voltage states: (1) a high resistance current-voltage state, and (2) a low resistance current-voltage state, wherein when a first positive threshold voltage (V.sub.th1) or higher positive voltage, or a second negative threshold voltage (V.sub.th2) or higher negative voltage is applied to the nanoparticle, the nanoparticle exhibits the low-resistance current-voltage state, and when a voltage less positive than the first positive threshold voltage or a voltage less negative than the second negative threshold voltage is applied to the nanoparticle, the nanoparticle exhibits the high-resistance current-voltage state. The present invention is also directed methods of manufacturing the nanoparticles using novel interfacial oxidative polymerization techniques.

  11. What makes polymer crystallization depend on time

    Science.gov (United States)

    Piccarolo, Stefano

    2015-12-01

    Here we report a series of objections to the mechanism of polymer crystallization by secondary nucleation plausible for very mild cooling conditions, i.e. when solidification time is long enough or when the molecular weight, M, is not too large, conditions not preventing segregation at the growth front to take place. With a manichean approach, if otherwise time is controlling, e.g. in polymer processing, or M is large, segregation is precluded and accumulation of topological defects takes place in the amorphous phase preventing sequential growth of crystalline domains. A non crystalline phase forms very much departed from equilibrium, constrained by the crystalline domains and frozen to an extent dependent on the morphology developed. Consequences are discussed, themselves a proof that segregation simplifies topology when crystallization conditions are mild. A situation responsible for the often reported memory effects as well as for mechanical and rheological properties. Results collected from our own experimental evidence by the originally developed Continuous Cooling Transformation are discussed within this framework and related to the broad, albeit often overlooked, literature on subjects intimately connected to crystallization and therefore spanning different fields of polymer science. We focus our attention on two recent results opening the way to this new perspective on polymer crystallization: the onset of the nodular morphology in iPP also in the presence of the stable a-monoclinic phase and the extended crystallization behaviour of polyester blends once local mobility is enhanced. Observing that demixing at the growth front controls crystallization under processing conditions we speculate that the high cooling rate solidification experiment is but a peculiar transient rheological measurement. Implications of this view are far reaching as the crucial role of the melt before solidification is evident.

  12. Polymer/Solvent and Polymer/Polymer Interaction Studies

    Science.gov (United States)

    1980-09-01

    DCM and ATS are completely miscible. The sorption data described 1 2Jones, E. G., Pedrick , D. L., and Benadum, P. A., Polymer Characteri- zation Using...Encyclopedia of Polymer Science and Technology, Vol. 11, Wiley-Interscience, N.Y. (1969), p. 447. 12. Jones, E.G., Pedrick , D.L., and Benadum, P.A., Polymer

  13. Light-Driven Liquid Crystalline Materials: From Photo-Induced Phase Transitions and Property Modulations to Applications.

    Science.gov (United States)

    Bisoyi, Hari Krishna; Li, Quan

    2016-12-28

    Light-driven phenomena both in living systems and nonliving materials have enabled truly fascinating and incredible dynamic architectures with terrific forms and functions. Recently, liquid crystalline materials endowed with photoresponsive capability have emerged as enticing systems. In this Review, we focus on the developments of light-driven liquid crystalline materials containing photochromic components over the past decade. Design and synthesis of photochromic liquid crystals (LCs), photoinduced phase transitions in LC, and photoalignment and photoorientation of LCs have been covered. Photomodulation of pitch, polarization, lattice constant and handedness inversion of chiral LCs is discussed. Light-driven phenomena and properties of liquid crystalline polymers, elastomers, and networks have also been analyzed. The applications of photoinduced phase transitions, photoalignment, photomodulation of chiral LCs, and photomobile polymers have been highlighted wherever appropriate. The combination of photochromism, liquid crystallinity, and fabrication techniques has enabled some fascinating functional materials which can be driven by ultraviolet, visible, and infrared light irradiation. Nanoscale particles have been incorporated to widen and diversify the scope of the light-driven liquid crystalline materials. The developed materials possess huge potential for applications in optics, photonics, adaptive materials, nanotechnology, etc. The challenges and opportunities in this area are discussed at the end of the Review.

  14. Optical waveguides in hard crystalline materials

    NARCIS (Netherlands)

    Pollnau, M.

    2005-01-01

    The recent results of our research group and collaborators in the field of fabrication, characterization, and applications of optical waveguides in hard crystalline materials, specifically in sapphire and Ti:sapphire, are reviewed.

  15. In vivo human crystalline lens topography

    OpenAIRE

    Ortiz, Sergio; Pérez Merino, Pablo; Gambra, Enrique; Castro, Alberto; Marcos, Susana

    2012-01-01

    Custom high-resolution high-speed anterior segment spectral domain optical coherence tomography (OCT) was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo. The system was provided with custom algorithms for denoising and segmentation of the images, as well as for fan (scanning) and optical (refraction) distortion correction, to provide fully quantitative images of the anterior and posterior crystalline lens surfaces. The method was tested on an artificial eye ...

  16. Revealing crystalline domains in a mollusc shell single-crystalline prism

    Science.gov (United States)

    Mastropietro, F.; Godard, P.; Burghammer, M.; Chevallard, C.; Daillant, J.; Duboisset, J.; Allain, M.; Guenoun, P.; Nouet, J.; Chamard, V.

    2017-09-01

    Biomineralization integrates complex processes leading to an extraordinary diversity of calcareous biomineral crystalline architectures, in intriguing contrast with the consistent presence of a sub-micrometric granular structure. Hence, gaining access to the crystalline architecture at the mesoscale, that is, over a few granules, is key to building realistic biomineralization scenarios. Here we provide the nanoscale spatial arrangement of the crystalline structure within the `single-crystalline' prisms of the prismatic layer of a Pinctada margaritifera shell, exploiting three-dimensional X-ray Bragg ptychography microscopy. We reveal the details of the mesocrystalline organization, evidencing a crystalline coherence extending over a few granules. We additionally prove the existence of larger iso-oriented crystalline domains, slightly misoriented with respect to each other, around one unique rotation axis, and whose shapes are correlated with iso-strain domains. The highlighted mesocrystalline properties support recent biomineralization models involving partial fusion of oriented nanoparticle assembly and/or liquid droplet precursors.

  17. Crystalline Silicon Dielectrics for Superconducting Qubit Circuits

    Science.gov (United States)

    Hover, David; Peng, Weina; Sendelbach, Steven; Eriksson, Mark; McDermott, Robert

    2009-03-01

    Superconducting qubit energy relaxation times are limited by microwave loss induced by a continuum of two-level state (TLS) defects in the dielectric materials of the circuit. State-of-the-art phase qubit circuits employ a micron-scale Josephson junction shunted by an external capacitor. In this case, the qubit T1 time is directly proportional to the quality factor (Q) of the capacitor dielectric. The amorphous capacitor dielectrics that have been used to date display intrinsic Q of order 10^3 to 10^4. Shunt capacitors with a Q of 10^6 are required to extend qubit T1 times well into the microsecond range. Crystalline dielectric materials are an attractive candidate for qubit capacitor dielectrics, due to the extremely low density of TLS defects. However, the robust integration of crystalline dielectrics with superconducting qubit circuits remains a challenge. Here we describe a novel approach to the realization of high-Q crystalline capacitor dielectrics for superconducting qubit circuits. The capacitor dielectric is a crystalline silicon nanomembrane. We discuss characterization of crystalline silicon capacitors with low-power microwave transport measurements at millikelvin temperatures. In addition, we report progress on integrating the crystalline capacitor process with Josephson qubit fabrication.

  18. DETERMINATION OF THE CRYSTALLINITY IN DIFFERENT TYPE POLY (OXYETHYLENE -STYRENE )BLOCK COPOLYMERS BY X- RAY DIFFRACTION METHOD

    Institute of Scientific and Technical Information of China (English)

    YAO Ning

    1989-01-01

    By means of the intensity theory of X- ray scattering and the two - phase concept of high polymer, the basic formula of the crystallinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene - styrene) block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene - styrene) block copolymers increases with the increase of the EO content and decreases in the order: PEO - PS - PEO > PEO - PS > PS - PEO - PS.

  19. Efectos de la calidad sanitaria de la caña semilla en los componentes del rendimiento cultural de las variedades CP 65-357 y LCP 85-384 (Saccharum spp., según diferentes edades de corte (Parte 2 Effects of seedcane quality on yielding components of CP 65-357 and LCP 85-384 (Saccharum spp. varieties at different crop ages (Part 2

    Directory of Open Access Journals (Sweden)

    María B. García

    2011-12-01

    Full Text Available Tradicionalmente, la mayoría de los productores de caña de azúcar de Tucumán utilizó en sus plantaciones, caña semilla proveniente de lotes comerciales con elevada infección de RSD (del inglés "ratoon stunting disease". Esta enfermedad sistémica, causada por Leifsonia xyli subsp. xyli, es ampliamente reconocida por su efecto detrimental sobre el rendimiento cultural. Desde hace pocos años, la disponibilidad de caña semilla saneada hizo viable la incorporación de cambios fundamentales en las prácticas culturales, que posibilitan aumentar la productividad de los cañaverales tucumanos. El objetivo del presente trabajo fue cuantificar el efecto de la calidad sanitaria de la caña semilla sobre el rendimiento cultural y sus componentes en dos variedades comerciales, LCP 85-384 y CP 65-357, a través de seis edades de corte. Este trabajo complementa la información obtenida para las tres primeras edades de corte, ya publicada. Se evaluaron dos calidades de caña semilla: semilla de alta calidad (SAC, saneada por cultivo de meristemas y multiplicada por propagación in vitro, y semilla comercial (SC infectada con RSD. Los tratamientos se implantaron en un diseño en bloques completos al azar con seis repeticiones. En cada edad se evaluaron: número de tallos/ parcela y peso, altura y diámetro de los tallos. Mediante el análisis de la varianza y pruebas de comparación de medias (DMS de Fisher, se determinó que la calidad sanitaria de la semilla afecta los componentes del rendimiento cultural. Se verificaron diferencias a favor de la semilla SAC para peso y altura de los tallos y, en menor medida, para número de tallos. El diámetro de los tallos no resultó afectado por la calidad de la semilla. Para cada edad, se registraron importantes disminuciones en la producción de caña/ha en los tratamientos provenientes de SC respecto a los originados de SAC. Considerando la producción acumulada en las seis cosechas (planta a soca 5, los

  20. Crosslinking of Trimethylene Carbonate and D,L-Lactide (Co-) Polymers by Gamma Irradiation in the Presence of Pentaerythritol Triacrylate

    NARCIS (Netherlands)

    Bat, Erhan; van Kooten, Theo G.; Feijen, Jan; Grijpma, Dirk W.

    2011-01-01

    High-molecular-weight (co) polymers of trimethylene carbonate and D, L-lactide are efficiently crosslinked using PETA during gamma irradiation. Form-stable networks with gel contents of 86 +/- 5 to 96 +/- 1 are obtained from non-crystalline (co) polymers. Glass transition temperatures and elastic mo

  1. Stability and cytotoxicity of crystallin amyloid nanofibrils

    Science.gov (United States)

    Kaur, Manmeet; Healy, Jackie; Vasudevamurthy, Madhusudan; Lassé, Moritz; Puskar, Ljiljana; Tobin, Mark J.; Valery, Celine; Gerrard, Juliet A.; Sasso, Luigi

    2014-10-01

    Previous work has identified crystallin proteins extracted from fish eye lenses as a cheap and readily available source for the self-assembly of amyloid nanofibrils. However, before exploring potential applications, the biophysical aspects and safety of this bionanomaterial need to be assessed so as to ensure that it can be effectively and safely used. In this study, crude crystallin amyloid fibrils are shown to be stable across a wide pH range, in a number of industrially relevant solvents, at both low and high temperatures, and in the presence of proteases. Crystallin nanofibrils were compared to well characterised insulin and whey protein fibrils using Thioflavin T assays and TEM imaging. Cell cytotoxicity assays suggest no adverse impact of both mature and fragmented crystallin fibrils on cell viability of Hec-1a endometrial cells. An IR microspectroscopy study supports long-term structural integrity of crystallin nanofibrils.Previous work has identified crystallin proteins extracted from fish eye lenses as a cheap and readily available source for the self-assembly of amyloid nanofibrils. However, before exploring potential applications, the biophysical aspects and safety of this bionanomaterial need to be assessed so as to ensure that it can be effectively and safely used. In this study, crude crystallin amyloid fibrils are shown to be stable across a wide pH range, in a number of industrially relevant solvents, at both low and high temperatures, and in the presence of proteases. Crystallin nanofibrils were compared to well characterised insulin and whey protein fibrils using Thioflavin T assays and TEM imaging. Cell cytotoxicity assays suggest no adverse impact of both mature and fragmented crystallin fibrils on cell viability of Hec-1a endometrial cells. An IR microspectroscopy study supports long-term structural integrity of crystallin nanofibrils. Electronic supplementary information (ESI) available: ThT fluorescence graphs of buffers and solvents used for

  2. Evaluating the effects of crystallinity in new biocompatible polyester nanocarriers on drug release behavior.

    Science.gov (United States)

    Karavelidis, Vassilios; Karavas, Evangelos; Giliopoulos, Dimitrios; Papadimitriou, Sofia; Bikiaris, Dimitrios

    2011-01-01

    Four new polyesters based on 1,3-propanediol and different aliphatic dicarboxylic acids were used to prepare ropinirole HCl-loaded nanoparticles. The novelty of this study lies in the use of polyesters with similar melting points but different degrees of crystallinity, varying from 29.8% to 67.5%, as drug nanocarriers. Based on their toxicity to human umbilical vein endothelial cells, these aliphatic polyesters were found to have cytotoxicity similar to that of polylactic acid and so may be considered as prominent drug nanocarriers. Drug encapsulation in polyesters was performed via an emulsification/solvent evaporation method. The mean particle size of drug-loaded nanoparticles was 164-228 nm, and the drug loading content was 16%-23%. Wide angle X-ray diffraction patterns showed that ropinirole HCl existed in an amorphous state within the nanoparticle polymer matrices. Drug release diagrams revealed a burst effect for ropinirole HCl in the first 6 hours, probably due to release of drug located on the nanoparticle surface, followed by slower release. The degree of crystallinity of the host polymer matrix seemed to be an important parameter, because higher drug release rates were observed in polyesters with a low degree of crystallinity.

  3. Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

    KAUST Repository

    Dimitrov, Stoichko

    2016-01-13

    The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law.

  4. Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Stoichko D. Dimitrov

    2016-01-01

    Full Text Available The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law.

  5. Side chain engineering of poly-thiophene and its impact on crystalline silicon based hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zellmeier, M.; Rappich, J.; Nickel, N. H. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Silicon Photovoltaics, Kekuléstr. 5, 12489 Berlin (Germany); Klaus, M.; Genzel, Ch. [Department of Microstructure and Residual Stress Analysis, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Janietz, S. [Department of Polymer Electronics, Fraunhofer Institute for Applied Polymer Research, Geiselbergstr. 69, 14476 Potsdam (Germany); Frisch, J.; Koch, N. [Humboldt Universität zu Berlin, Brook-Taylor-Straße 6, 12489 Berlin (Germany)

    2015-11-16

    The influence of ether groups in the side chain of spin coated regioregular polythiophene derivatives on the polymer layer formation and the hybrid solar cell properties was investigated using electrical, optical, and X-ray diffraction experiments. The polymer layers are of high crystallinity but the polymer with 3 ether groups in the side chain (P3TOT) did not show any vibrational fine structure in the UV-Vis spectrum. The presence of ether groups in the side chains leads to better adhesion resulting in thinner and more homogeneous polymer layers. This, in turn, enhances the electronic properties of the planar c-Si/poly-thiophene hybrid solar cell. We find that the power conversion efficiency increases with the number of ether groups in the side chains, and a maximum power conversion efficiency of η = 9.6% is achieved even in simple planar structures.

  6. Composite Polymer Electrolytes: Nanoparticles Affect Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2016-11-01

    Full Text Available Composite polymer electrolytes (CPEs can significantly improve the performance in electrochemical devices such as lithium-ion batteries. This review summarizes property/performance relationships in the case where nanoparticles are introduced to polymer electrolytes. It is the aim of this review to provide a knowledge network that elucidates the role of nano-additives in the CPEs. Central to the discussion is the impact on the CPE performance of properties such as crystalline/amorphous structure, dielectric behavior, and interactions within the CPE. The amorphous domains of semi-crystalline polymer facilitate the ion transport, while an enhanced mobility of polymer chains contributes to high ionic conductivity. Dielectric properties reflect the relaxation behavior of polymer chains as an important factor in ion conduction. Further, the dielectric constant (ε determines the capability of the polymer to dissolve salt. The atom/ion/nanoparticle interactions within CPEs suggest ways to enhance the CPE conductivity by generating more free lithium ions. Certain properties can be improved simultaneously by nanoparticle addition in order to optimize the overall performance of the electrolyte. The effects of nano-additives on thermal and mechanical properties of CPEs are also presented in order to evaluate the electrolyte competence for lithium-ion battery applications.

  7. Structure and Morphology Control in Thin Films of Conjugated Polymers for an Improved Charge Transport

    Directory of Open Access Journals (Sweden)

    Haiyang Wang

    2013-11-01

    Full Text Available The morphological and structural features of the conjugated polymer films play an important role in the charge transport and the final performance of organic optoelectronics devices [such as organic thin-film transistor (OTFT and organic photovoltaic cell (OPV, etc.] in terms of crystallinity, packing of polymer chains and connection between crystal domains. This review will discuss how the conjugated polymer solidify into, for instance, thin-film structures, and how to control the molecular arrangement of such functional polymer architectures by controlling the polymer chain rigidity, polymer solution aggregation, suitable processing procedures, etc. These basic elements in intrinsic properties and processing strategy described here would be helpful to understand the correlation between morphology and charge transport properties and guide the preparation of efficient functional conjugated polymer films correspondingly.

  8. Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

    Science.gov (United States)

    Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

    2016-03-14

    Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

  9. SYNTHESIS OF A GROUP OF MESOGEN-JACKETED LIQUID CRYSTAL POLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHU Xinlong; YANG Qingchuan; ZHOU Qifeng

    1992-01-01

    A group of the mesogen jacketed liquid crystal polymers based on the monomers 2,5-bis (4-substituted benzoyl)oxystyrenes are synthesized. The substituents include alkoxy, alkyl, and cyano groups. The synthesis and the primary characterization of the liquid crystal phase of the monomers and the polymers are described. While some of the monomers give smectic textures the polymers are found to be nematic above their melting or glass transition temperatures. Interestingly the unsubstituted monomer and its polymer poly 2,5-di( benzoyloxy ) styrene are also liquid crystalline. The single crystal structure of one of the monomers is also discussed.

  10. STRUCTURAL AND MECHANICAL CHARACTERIZATION OF DEFORMED POLYMER USING CONFOCAL RAMAN MICROSCOPY AND DSC

    Directory of Open Access Journals (Sweden)

    Birgit Neitzel

    2016-02-01

    Full Text Available Polymers have various interesting properties, which depend largely on their inner structure. One way to influence the macroscopic behaviour is the deformation of the polymer chains, which effects the change in microstructure. For analyzing the microstructure of non-deformed and deformed polymer materials, Raman spectroscopy as well as differential scanning calorimetry (DSC were used. In the present study we compare the results for crystallinity measurements of deformed polymers using both methods in order to characterize the differences in micro-structure due to deformation. The study is ongoing, and we present the results of the first tests.

  11. SYNTHESIS AND CHARACTERIZATION OF COMB-LIKE POLYMERS BEARING HETEROCYCLIC AZO GROUP AND MESOGENIC GROUP

    Institute of Scientific and Technical Information of China (English)

    Hui-qi Zhang; Wen-qiang Huang; Chen-xi Li; Bing-lin He

    1999-01-01

    The synthesis and characterization of a series of novel comb-like polymethacrylates bearing heterocyclic azo group and mesogenic group are described. The thermal properties of the polymers such as thermal stability and phase transition behavior were investigated by thermogravimetric analysis, differential thermal analysis and polarizing optical microscopy techniques. The experimental results show that all the synthesized polymers do not exhibit liquid crystallinity except the homopolymer of the mesogenic monomer MAPB2 and the glass transition temperatures of the polymers increase with increasing content of azo moiety in polymers linearly.

  12. An investigation about the solid state thermal degradation of acetylsalicylic acid: polymer formation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Edna M. de A; Melo, Dulce M. de A; Moura, Maria de F.V. de; Farias, Robson F. de

    2004-05-06

    An investigation about the thermal degradation of acetylsalicylic acid (ASA) is performed. It is verified that the thermal degradation of ASA produces not only salicylic acid (SA) and acetic acid (AA) as products but also an ASA polymer, which is transparent and solid. And also verified that the temperature in which the polymer is obtained influences its physical consistence (solid or semi-solid). Furthermore, the ASA polymer is very stable from a thermic point of view, as verified by TG and DSC analysis. X-ray diffraction patterns obtained for the ASA polymer show that it exhibits a low crystallinity.

  13. Impact of solvents and supercritical CO{sub 2} drying on the morphology and structure of polymer-based biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Causa, Andrea; Acierno, Domenico; Filippone, Giovanni [Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università di Napoli Federico II, Piazzale V. Tecchio, 80, 80125 Napoli (Italy); Salerno, Aurelio; Domingo, Concepción [Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra (Spain)

    2014-05-15

    In the present work, two-dimensional systems based on biodegradable polymers such as poly(ε-caprolactone) (PCL), poly(ethylene oxide) (PEO) and polylactic acid (PLA) are fabricated by means of a sustainable approach which consists in inducing phase separation in solutions of such polymers and “green” solvents, namely ethyl lactate (EL) and ethyl acetate (EA). The extraction of the solvent is promoted by a controlled drying process, which is performed in either air or supercritical CO{sub 2}. The latter can indeed act as both an antisolvent, which favors the deposition of the polymer by forming a mixture with EL and EA, and a plasticizing agent, whose solvation and transport properties may considerably affect the microstructure and crystallinity of the polymer films. The morphological, topographical and crystalline properties of the films are tailored through a judicial selection of the materials and the processing conditions and assessed by means of thermal analyses, polarized optical microscopy, scanning electron microscopy and confocal interferometric microscopy. The results show that the morphological and crystalline properties of the films are strongly dependent on the choice of both the polymer/solvent system and the operating conditions during the drying step. In particular, the morphological, topographical and thermal properties of films prepared starting from highly crystalline polymers, namely PCL and PEO, are greatly affected by the crystallization of the material. Conversely, the less crystalline PLA forms almost completely amorphous films.

  14. Impact of solvents and supercritical CO2 drying on the morphology and structure of polymer-based biofilms

    Science.gov (United States)

    Causa, Andrea; Salerno, Aurelio; Domingo, Concepción; Acierno, Domenico; Filippone, Giovanni

    2014-05-01

    In the present work, two-dimensional systems based on biodegradable polymers such as poly(ɛ-caprolactone) (PCL), poly(ethylene oxide) (PEO) and polylactic acid (PLA) are fabricated by means of a sustainable approach which consists in inducing phase separation in solutions of such polymers and "green" solvents, namely ethyl lactate (EL) and ethyl acetate (EA). The extraction of the solvent is promoted by a controlled drying process, which is performed in either air or supercritical CO2. The latter can indeed act as both an antisolvent, which favors the deposition of the polymer by forming a mixture with EL and EA, and a plasticizing agent, whose solvation and transport properties may considerably affect the microstructure and crystallinity of the polymer films. The morphological, topographical and crystalline properties of the films are tailored through a judicial selection of the materials and the processing conditions and assessed by means of thermal analyses, polarized optical microscopy, scanning electron microscopy and confocal interferometric microscopy. The results show that the morphological and crystalline properties of the films are strongly dependent on the choice of both the polymer/solvent system and the operating conditions during the drying step. In particular, the morphological, topographical and thermal properties of films prepared starting from highly crystalline polymers, namely PCL and PEO, are greatly affected by the crystallization of the material. Conversely, the less crystalline PLA forms almost completely amorphous films.

  15. Improved Josephson Qubits incorporating Crystalline Silicon Dielectrics

    Science.gov (United States)

    Gao, Yuanfeng; Maurer, Leon; Hover, David; Patel, Umeshkumar; McDermott, Robert

    2010-03-01

    Josephson junction phase quibts are a leading candidate for scalable quantum computing in the solid state. Their energy relaxation times are currently limited by microwave loss induced by a high density of two-level state (TLS) defects in the amorphous dielectric films of the circuit. It is expected that the integration of crystalline, defect-free dielectrics into the circuits will yield substantial improvements in qubit energy relaxation times. However, the epitaxial growth of a crystalline dielectric on a metal underlayer is a daunting challenge. Here we describe a novel approach in which the crystalline silicon nanomembrane of a Silicon-on-Insulator (SOI) wafer is used to form the junction shunt capacitor. The SOI wafer is thermocompression bonded to the device wafer. The handle and buried oxide layers of the SOI are then etched away, leaving the crystalline silicon layer for subsequent processing. We discuss device fabrication issues and present microwave transport data on lumped-element superconducting resonators incorporating the crystalline silicon.

  16. Ab initio prediction of the electronic and optical excitations in polythiophene: Isolated chains versus bulk polymer

    Science.gov (United States)

    van der Horst, J.-W.; Bobbert, P. A.; de Jong, P. H. L.; Michels, M. A. J.; Brocks, G.; Kelly, P. J.

    2000-06-01

    We calculate the electronic and optical excitations of polythiophene using the GW (G stands for one-electron Green function, W for the screened Coulomb interaction) approximation for the electronic self-energy, and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. Two different situations are studied: excitations on isolated chains and excitations on chains in crystalline polythiophene. The dielectric tensor for the crystalline situation is obtained by modeling the polymer chains as polarizable line objects, with a long-wavelength polarizability tensor obtained from the ab initio polarizability function of the isolated chain. With this model dielectric tensor we construct a screened interaction for the crystalline case, including both intra- and interchain screening. In the crystalline situation both the quasiparticle band gap and the exciton binding energies are drastically reduced in comparison with the isolated chain. However, the optical gap is hardly affected. We expect this result to be relevant for conjugated polymers in general.

  17. ZnO Coatings with Controlled Pore Size, Crystallinity and Electrical Conductivity

    Directory of Open Access Journals (Sweden)

    Roman SCHMACK

    2016-05-01

    Full Text Available Zinc oxide is a wide bandgap semiconductor with unique optical, electrical and catalytic properties. Many of its practical applications rely on the materials pore structure, crystallinity and electrical conductivity. We report a synthesis method for ZnO films with ordered mesopore structure and tuneable crystallinity and electrical conductivity. The synthesis relies on dip-coating of solutions containing micelles of an amphiphilic block copolymer and complexes of Zn2+ ions with aliphatic ligands. A subsequent calcination at 400°C removes the template and induces crystallization of the pore walls. The pore structure is controlled by the template polymer, whereas the aliphatic ligands control the crystallinity of the pore walls. Complexes with a higher thermal stability result in ZnO films with a higher content of residual carbon, smaller ZnO crystals and therefore lower electrical conductivity. The paper discusses the ability of different types of ligands to assist in the synthesis of mesoporous ZnO and relates the structure and thermal stability of the precursor complexes to the crystallinity and electrical conductivity of the zinc oxide.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8634

  18. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Energy Technology Data Exchange (ETDEWEB)

    Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India); Methattel Raman, Shijeesh [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India)

    2016-04-18

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  19. ZnO Coatings with Controlled Pore Size, Crystallinity and Electrical Conductivity

    Directory of Open Access Journals (Sweden)

    Roman SCHMACK

    2016-05-01

    Full Text Available Zinc oxide is a wide bandgap semiconductor with unique optical, electrical and catalytic properties. Many of its practical applications rely on the materials pore structure, crystallinity and electrical conductivity. We report a synthesis method for ZnO films with ordered mesopore structure and tuneable crystallinity and electrical conductivity. The synthesis relies on dip-coating of solutions containing micelles of an amphiphilic block copolymer and complexes of Zn2+ ions with aliphatic ligands. A subsequent calcination at 400°C removes the template and induces crystallization of the pore walls. The pore structure is controlled by the template polymer, whereas the aliphatic ligands control the crystallinity of the pore walls. Complexes with a higher thermal stability result in ZnO films with a higher content of residual carbon, smaller ZnO crystals and therefore lower electrical conductivity. The paper discusses the ability of different types of ligands to assist in the synthesis of mesoporous ZnO and relates the structure and thermal stability of the precursor complexes to the crystallinity and electrical conductivity of the zinc oxide.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8634

  20. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Science.gov (United States)

    Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

    2016-04-01

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  1. Partial Discharge Degradation of Several Biodegradable Polymers

    Science.gov (United States)

    Fuse, Norikazu; Fujita, Shinjiro; Hirai, Naoshi; Tanaka, Toshikatsu; Kozako, Masahiro; Kohtoh, Masanori; Okabe, Shigemitsu; Ohki, Yoshimichi

    Partial discharge (PD) resistance was examined by applying a constant voltage for four kinds of biodegradable polymers, i.e. poly-L-lactic acid (PLLA), polyethylene terephthalate succinate (PETS), poly ε-caprolactone butylene succinate (PCL-BS), and polybutylene succinate (PBS), and the results were compared with those of low density polyethylene (LDPE) and crosslinked low density polyethylene (XLPE). The PD resistance is determined by the erosion depth and the surface roughness caused by PDs, and is ranked as LDPE ≅ XLPE > PLLA ≅ PETS > PBS > PCL-BS. This means that the sample with a lower permittivity has better PD resistance. Furthermore, observations of the sample surface by a polarization microscope and a laser confocal one reveal that crystalline regions with spherulites are more resistant to PDs than amorphous regions. Therefore, good PD resistance can be achieved by the sample with a high crystallinity and a low permittivity.

  2. Comparative Community Proteomics Demonstrates the Unexpected Importance of Actinobacterial Glycoside Hydrolase Family 12 Protein for Crystalline Cellulose Hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Hiras, Jennifer; Wu, Yu-Wei; Deng, Kai; Nicora, Carrie D.; Aldrich, Joshua T.; Frey, Dario; Kolinko, Sebastian; Robinson, Errol W.; Jacobs, Jon M.; Adams, Paul D.; Northen, Trent R.; Simmons, Blake A.; Singer, Steven W.

    2016-08-23

    ABSTRACT

    Glycoside hydrolases (GHs) are key enzymes in the depolymerization of plant-derived cellulose, a process central to the global carbon cycle and the conversion of plant biomass to fuels and chemicals. A limited number of GH families hydrolyze crystalline cellulose, often by a processive mechanism along the cellulose chain. During cultivation of thermophilic cellulolytic microbial communities, substantial differences were observed in the crystalline cellulose saccharification activities of supernatants recovered from divergent lineages. Comparative community proteomics identified a set of cellulases from a population closely related to actinobacteriumThermobispora bisporathat were highly abundant in the most active consortium. Among the cellulases fromT. bispora, the abundance of a GH family 12 (GH12) protein correlated most closely with the changes in crystalline cellulose hydrolysis activity. This result was surprising since GH12 proteins have been predominantly characterized as enzymes active on soluble polysaccharide substrates. Heterologous expression and biochemical characterization of the suite ofT. bisporahydrolytic cellulases confirmed that the GH12 protein possessed the highest activity on multiple crystalline cellulose substrates and demonstrated that it hydrolyzes cellulose chains by a predominantly random mechanism. This work suggests that the role of GH12 proteins in crystalline cellulose hydrolysis by cellulolytic microbes should be reconsidered.

    IMPORTANCECellulose is the most abundant organic polymer on earth, and its enzymatic hydrolysis is a key reaction in the global carbon cycle and the conversion of plant biomass to biofuels. The glycoside hydrolases that depolymerize crystalline cellulose have been primarily characterized from isolates. In this study, we demonstrate that adapting microbial consortia from compost to grow on crystalline cellulose

  3. Comparative Community Proteomics Demonstrates the Unexpected Importance of Actinobacterial Glycoside Hydrolase Family 12 Protein for Crystalline Cellulose Hydrolysis.

    Science.gov (United States)

    Hiras, Jennifer; Wu, Yu-Wei; Deng, Kai; Nicora, Carrie D; Aldrich, Joshua T; Frey, Dario; Kolinko, Sebastian; Robinson, Errol W; Jacobs, Jon M; Adams, Paul D; Northen, Trent R; Simmons, Blake A; Singer, Steven W

    2016-08-23

    Glycoside hydrolases (GHs) are key enzymes in the depolymerization of plant-derived cellulose, a process central to the global carbon cycle and the conversion of plant biomass to fuels and chemicals. A limited number of GH families hydrolyze crystalline cellulose, often by a processive mechanism along the cellulose chain. During cultivation of thermophilic cellulolytic microbial communities, substantial differences were observed in the crystalline cellulose saccharification activities of supernatants recovered from divergent lineages. Comparative community proteomics identified a set of cellulases from a population closely related to actinobacterium Thermobispora bispora that were highly abundant in the most active consortium. Among the cellulases from T. bispora, the abundance of a GH family 12 (GH12) protein correlated most closely with the changes in crystalline cellulose hydrolysis activity. This result was surprising since GH12 proteins have been predominantly characterized as enzymes active on soluble polysaccharide substrates. Heterologous expression and biochemical characterization of the suite of T. bispora hydrolytic cellulases confirmed that the GH12 protein possessed the highest activity on multiple crystalline cellulose substrates and demonstrated that it hydrolyzes cellulose chains by a predominantly random mechanism. This work suggests that the role of GH12 proteins in crystalline cellulose hydrolysis by cellulolytic microbes should be reconsidered. Cellulose is the most abundant organic polymer on earth, and its enzymatic hydrolysis is a key reaction in the global carbon cycle and the conversion of plant biomass to biofuels. The glycoside hydrolases that depolymerize crystalline cellulose have been primarily characterized from isolates. In this study, we demonstrate that adapting microbial consortia from compost to grow on crystalline cellulose generated communities whose soluble enzymes exhibit differential abilities to hydrolyze crystalline

  4. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  5. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  6. Structural changes in bunched crystalline ion beams

    CERN Document Server

    Bussmann, M; Schätz, T; Habs, D

    2003-01-01

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions.

  7. Cooling and heating of crystalline ion beams

    CERN Document Server

    Schramm, U; Bussmann, M; Habs, D

    2003-01-01

    The crystallization of ion beams has recently been established in the rf quadrupole storage ring PALLAS (PAul Laser CooLing Acceleration System) for laser-cooled sup 2 sup 4 Mg sup + ion beams at an energy of about 1 eV. Yet, unexpectedly sharp constraints had to be met concerning the confinement strength and the longitudinal laser cooling rate. In this paper, related and up to now unseen heating mechanisms are pinpointed for crystalline beams. The weak but inevitable diffusive transverse heating associated with the laser cooling process itself is investigated, possibly allowing the future measurement of the latent heat of the ion crystal. As a function of the beam velocity, the influence of bending shear on the attainability of larger crystalline structures is presented. Finally, rf heating of crystalline beams of different structure is studied for discontinuous cooling.

  8. Liquid Crystalline Materials for Biological Applications.

    Science.gov (United States)

    Lowe, Aaron M; Abbott, Nicholas L

    2012-03-13

    Liquid crystals have a long history of use as materials that respond to external stimuli (e.g., electrical and optical fields). More recently, a series of investigations have reported the design of liquid crystalline materials that undergo ordering transitions in response to a range of biological interactions, including interactions involving proteins, nucleic acids, viruses, bacteria and mammalian cells. A central challenge underlying the design of liquid crystalline materials for such applications is the tailoring of the interface of the materials so as to couple targeted biological interactions to ordering transitions. This review describes recent progress toward design of interfaces of liquid crystalline materials that are suitable for biological applications. Approaches addressed in this review include the use of lipid assemblies, polymeric membranes containing oligopeptides, cationic surfactant-DNA complexes, peptide-amphiphiles, interfacial protein assemblies and multi-layer polymeric films.

  9. Crystalline Structures and Properties of Uniaxial Oriented Poly(ethylene chlorotrifluoroethylene Fiber

    Directory of Open Access Journals (Sweden)

    PAN Jian

    2016-07-01

    Full Text Available Uniaxial oriented poly (ethylene chlorotrifluoroethylene (ECTFE fibers were prepared by the melt spinning method using ECTFE resin as the fiber-forming polymer. The crystal structures,thermal and mechanical properties and creep resistance of the prepared fibers were analyzed by X-ray diffraction (XRD,differential scanning calorimetry (DSC,mechanical and creep performance testing,etc. Results show that, the uniaxial oriented ECTFE fibers have favourable crystallization property. Their crystalline structures belong to hexagonal system,the degree of crystalline orientation is about 90%. The uniaxial oriented ECTFE fibers have excellent mechanical properties,thermostability,creep resistance and chemical corrosion resistance (such as acid,alkali,strong oxidizing reagents,organic reagents,etc.

  10. Shape-memory effect of nanocomposites based on liquid-crystalline elastomers

    Science.gov (United States)

    Marotta, A.; Lama, G. C.; Gentile, G.; Cerruti, P.; Carfagna, C.; Ambrogi, V.

    2016-05-01

    In this work, nanocomposites based on liquid crystalline (LC) elastomers were prepared and characterized in their shape memory properties. For the synthesis of materials, p-bis(2,3-epoxypropoxy)-α-methylstilbene (DOMS) was used as mesogenic epoxy monomer, sebacic acid (SA) as curing agent and multi-walled carbon nanotubes (MWCNT) and graphene oxide (GO) as fillers. First, an effective compatibilization methodology was set up to improve the interfacial adhesion between the matrix and the carbonaceous nanofillers, thus obtaining homogeneous distribution and dispersion of the nanofillers within the polymer phase. Then, the obtained nanocomposite films were characterized in their morphological and thermal properties. In particular, the effect of the addition of the nanofillers on liquid crystalline behavior, as well as on shape-memory properties of the realized materials was investigated. It was found that both fillers were able to enhance the thermomechanical response of the LC elastomers, making them good candidates as shape memory materials.

  11. Phase behaviour of macromolecular liquid crystalline materials. Computational studies at the molecular level

    CERN Document Server

    Stimson, L M

    2003-01-01

    Molecular simulations provide an increasingly useful insight into the static and dynamic characteristics of materials. In this thesis molecular simulations of macro-molecular liquid crystalline materials are reported. The first liquid crystalline material that has been investigated is a side chain liquid crystal polymer (SCLCP). In this study semi-atomistic molecular dynamics simulations have been conducted at a range of temperatures and an aligning potential has been applied to mimic the effect of a magnetic field. In cooling the SCLCP from an isotropic melt, microphase separation was observed yielding a domain structure. The application of a magnetic field to this structure aligns the domains producing a stable smectic mesophase. This is the first study in which mesophases have been observed using an off-lattice model of a SCLCP. The second material that has been investigated is a dendrimer with terminal mesogenic functionalization. Here, a multi-scale approach has been taken with Monte Carlo studies of a s...

  12. 胫骨远端前外侧锁定钢板延期治疗复杂Pilon骨折%LCP Anterolateral Distal Tibia Plate for Treatment of Complex Pilon Fractures at a Delayed-stage

    Institute of Scientific and Technical Information of China (English)

    李宇; 黄涛; 葛俊波; 洪焕玉; 张海光

    2013-01-01

    目的:探讨延期切开复位结合胫骨远端前外侧“L”形锁定钢板治疗复杂Pilon骨折.方法:30例Pilon骨折患者,按AO分类方式,所有患者均为C型:C1型7例,C2型15例,C3型8例.6例为开放性骨折,24例为闭合性骨折,延迟手术时间为7~14d(平均10.5d),待肿胀消退后行切开复位结合胫骨远端前外侧“L”形锁定钢板内固定治疗.结果:30例均获术后随访,随访时间14~28个月(平均18.5个月).骨折临床愈合时间为12~23个月(平均14.3个月).术后有2例伤口感染;3例皮肤坏死;5例出现骨折延迟愈合,其中2例再次行植骨手术;1例过早负重,导致骨折端畸形愈合.临床疗效根据AOFAS评分系统进行评定:优18例,良9,可3例,优良率为90%.结论:严重Pilon骨折根据不同的骨折类型、软组织损伤程度选择不同的手术方式和手术时机非常重要.延期切开复位结合胫骨远端前外侧“L”形锁定钢板是临床治疗复杂Pilon骨折的理想方法.%Objective:To detect the curative effect of delayed open reduction and "L"-shaped LCP anterolateral distal tibia plate for treating of complex Pilon fractures.Methods:A total of 30 cases of Pilon fractures were treated by open reduction and "L"-shaped LCP anterolateral distal tibia plate after improvement of soft tissue conditions.All the cases were type C fracture according to AO classification,7 cases of which were type C1,15 cases were type C2,and 8 cases were type C3.There were 6 cases of open Pilon fractures and 24 cases of closed fractures.Operations were performed on average 10.5days after the injuries (range 7 to 14 days).Results:All the patients were followed-up for 14 months to 28 months (18.5months averagely).The average healing times was 12 to 23 months (14.3 months averagely).There were 2 cases of wound infection,3 cases of cutaneous necrosis,and 5 cases of delayed bone healing,including two cases of bone grafting surgery again.There was also one case of

  13. Influence of Hydroxypropyl Methylcellulose on Metronidazole Crystallinity in Spray-Congealed Polyethylene Glycol Microparticles and Its Impact with Various Additives on Metronidazole Release.

    Science.gov (United States)

    Oh, Ching Mien; Heng, Paul Wan Sia; Chan, Lai Wah

    2015-12-01

    The purpose of this study was to investigate the effect of a hydrophilic polymer, hydroxypropyl methylcellulose (HPMC), on the crystallinity and drug release of metronidazole (MNZ) in spray-congealed polyethylene glycol (PEG) microparticles and to further modify the drug release using other additives in the formulation. HPMC has been used in many pharmaceutical formulations and processes but to date, it has not been employed as an additive in spray congealing. Crystallinity of a drug is especially important to the development of pharmaceutical products as active pharmaceutical ingredients (APIs) are mostly crystalline in nature. A combination of X-ray diffractometry, differential scanning calorimetry, Raman spectroscopy and Fourier transform-infrared spectroscopy (FT-IR) spectroscopy was employed to investigate the degree of crystallinity and possible solid-state structure of MNZ in the microparticles. The microparticles with HPMC were generally spherical. Spray congealing decreased MNZ crystallinity, and the presence of HPMC reduced the drug crystallinity further. The reduction in MNZ crystallinity was dependent on the concentration of HPMC. Smaller HPMC particles also resulted in a greater percentage reduction in MNZ crystallinity. Appreciable modification to MNZ release could be obtained with HPMC. However, this was largely attributed to the role of HPMC in forming a diffusion barrier. Further modification of drug release from spray-congealed PEG-HPMC microparticles was achieved with the addition of 5% w/w dicalcium phosphate but not with magnesium stearate, methyl cellulose, polyvinylpyrrolidone, silicon dioxide and sodium oleate/citric acid. Dicalcium phosphate facilitated formation of the diffusion barrier.

  14. Effect of time and temperature exposition in the crystallinity degree of sulfonated poly-(styrene acrylic acid) (PSAA-S)

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, G.W.; Becker, E.B.; Silva, L.; Naspolini, A.M.; Consenso, E.C.; Paula, M.M.S.; Fiori, M.A., E-mail: glau_bn@hotmail.co [University of Extreme South of Santa Catarina Criciuma, SC (Brazil). Dept. of Materials Engineering; Silveira, F.Z. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Chemical Engineering

    2010-07-01

    Polymers with special properties have been increasingly applied in the development of technological devices. For example, polymeric materials with special electric properties, such as sulfonated poly-(styrene-acrylic acid) - PSAA-S, are of great interest for showing different conductivities depending on the environment where they are applied. The special properties of PSAA are obtained only after sulfonation step in acidic media. The present work aimed to evaluate the effect of time and temperature exposition in the crystallinity degree of PSAA-S, through a statistical experimental factorial planning. The samples of PSAA-S were submitted to FT-IR and DRX tests. The results showed that the temperature and the time of exposition are significant factors in the crystallinity degree of PSAA-S, considering that the crystal lattices created during the polymerization are damaged by the action of time and temperature at which the polymer is exposed. (author)

  15. Morphological Evolution During Tensile Deformation in Semi-Crystalline Precise Functional Copolymers via Fitting of In Situ Xray Scattering

    Science.gov (United States)

    Trigg, Edward B.; Middleton, L. Robert; Aitken, Brian S.; Azoulay, Jason; Murtagh, Dustin; Wagener, Kenneth B.; Cordaro, Joseph; Winey, Karen I.

    Morphological evolution during tensile deformation of semi-crystalline polymers is often described qualitatively. The layered crystal structures of precise copolymers, in which functional groups are bonded at precise intervals along the polymer backbone, allow for quantitative fitting of oriented X-ray scattering peaks to provide additional information. The crystallites in precise poly(ethylene-co-acrylic acid) align with the acid group layers' normal vector parallel to the tensile direction, while those in precise poly(ethylene-co-imidazolium bromide) align with the layers' normal vector perpendicular to the tensile direction. We present fits of in situ X-ray scattering during tensile deformation of semi-crystalline precise copolymers, to quantify the size, shape, and degree of orientation of the crystallites during the deformation process. Mathematical descriptions of the X-ray scattering in these two cases is explored, and a physical explanation for the difference in alignment direction is proposed.

  16. Electronic processes in non-crystalline materials

    CERN Document Server

    Mott, Nevill Francis

    2012-01-01

    Since the first edition of this highly successful book the field saw many great developments both in experimental and theoretical studies of electrical properties of non-crystalline solids. It became necessary to rewrite nearly the whole book, while the aims of the second edition remained the same: to set out the theoretical concepts, to test them by comparison with experiment for a wide variety of phenomena, and to apply them to non-crystalline materials. Sir Nevill Mott shared the1977 Nobel Prize for Physics, awarded for his research work in this field. The reissue of this book as part of th

  17. Used fuel disposition in crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hadgu, Teklu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kalinina, Elena Arkadievna [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cruse, T. [Argonne National Lab. (ANL), Argonne, IL (United States); Ebert, W. [Argonne National Lab. (ANL), Argonne, IL (United States); Buck, E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Eittman, R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tinnacher, R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Tournassat, Christophe. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davis, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Viswanathan, H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, F. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Joseph, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-01

    The U.S. Department of Energy Office of Nuclear Energy, Office of Fuel Cycle Technology established the Used Fuel Disposition Campaign (UFDC) in fiscal year 2010 (FY10) to conduct the research and development (R&D) activities related to storage, transportation and disposal of used nuclear fuel and high level nuclear waste. The objective of the Crystalline Disposal R&D Work Package is to advance our understanding of long-term disposal of used fuel in crystalline rocks and to develop necessary experimental and computational capabilities to evaluate various disposal concepts in such media.

  18. Exact Topological Twistons in Crystalline Polyethylene

    CERN Document Server

    Ventura, E; Bazeia, D

    2000-01-01

    We investigate the presence of topological twistons in crystalline polyethylene. We describe crystalline polyethylene with a model that couples the torsional and longitudinal degrees of freedom of the polymeric chain by means of a system of two real scalar fields. This model supports topological twistons, which are described by exact and stable topological solutions that appear when the interaction between torsional and longitudinal fields is polynomial, containing up to the sixth power in the fields. We calculate the energy of the topological twiston, and the result is in very good agreement with the value obtained via molecular simulation.

  19. Observation of atomic collisions in crystalline solids

    CERN Document Server

    Nelson, R S; Gevers, R

    2013-01-01

    The Observation of Atomic Collisions in Crystalline Solids presents a critical account of the more important experiments which have provided the basis for a better understanding of atomic collision phenomena in crystalline solids. Collisions have been divided into two artificial regimes; primary collisions which deal with the interaction of the incident particles with the solid, and secondary collisions which deal with those events which occur as a result of lattice atoms recoiling from primary encounters. Although the book is intended principally for the experimentalist some simple theoretica

  20. Biodegradable and bioabsorbable polymers. Seitai bunkaiter dot kyushu sei kobunshi

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y. (Kyoto Inst. of Technology, Kyoto (Japan). Faculty of Textile Science)

    1991-08-20

    The relationship between biodegradability with the layout and structure of high polymers which are degraded and disintegrated by the contact with organism is investigated. Description is made also on a new polyurethane which is decomposed by the action of E. Coli. Vinyl polymers formed by carbon-carbon bonding is hard to be made biodegradable with a few exceptions. If the chemical structures are similar, the rates of the decomposition are in the order of crystalline high polymer < glass state high polymer < rubber state high polymer. Bioabsorbable polymers disappear in a short time even implanted in body, and are used ideally as temporary mending materials during the period of body{prime}s self recovery and as the carriers for slow release drugs. Development of biodegradable polymers which can be decomposed by microbes in soil and sea water are expected to be most likely. Non-absorbable degradable polymers which are decomposed, with the decomposed products remaining in body for a long time, can function well in dischargeable portions. 38 refs., 3 tabs.

  1. Advanced Polymer Electrolytes for High-energy-density Power Sources

    Institute of Scientific and Technical Information of China (English)

    D. Golodnitsky; E. Livshits; R. Kovarsky; E. Peled

    2005-01-01

    @@ 1Introduction The preparation of highly controlled thin films of lithium ion conducting organic materials is becoming a challenging but rewarding goal in view of obtaining high-performance technological devices like solid-state polymer batteries and capacitors. The classical polymer electrolyte consists of organic macromolecules (usually polyether polymer) that are doped with inorganic (typically lithium) salts. Poly(ethylene oxide) (PEO) is the most commonly employed polymer in PEs because of the peculiar array in the (-CH2-CH2-O-)n chain providing the ability to solvate low-lattice-energy lithium salts. For three decades the major research attention was focused on amorphous polymer electrolytes in the belief that ionic conductivity occurs in a manner somewhat analogous to gas diffusion through polymer membranes. Segmental motion of the polymer chains continuously creates free volume, into which the ions migrate, and this process allows ions to progress across the electrolyte. Such a view was established by a number of experiments, and denied the possibility of ionic conductivity in crystalline polymer phases. This concept has been recently overturned by our group, demonstrating that conductivity comes about as a result of permanent conducting pathways for the movement of ions.

  2. Molecular composites and polymer blends containing ionic polymers

    Science.gov (United States)

    Tsou, Li-Chun

    1997-11-01

    Polymer blends are generally immiscible due to the unfavorable thermodynamics of mixing. By the introduction of ion-dipole interaction, mechanical properties of the PPTA anion/polar polymers (such as PVP, PEO and PPrO) molecular composites have been investigated in relation to their miscibility and microstructural morphology. Optical clarity observed in the glassy PPTA anion/PVP system suggest the presence of miscibility, since the refractive indices between the two components are quite different, nsb{PVP} = 1.509 and nsb{PPTA} = 1.644. In general, the difference greater than 0.01 is sufficient to make blends opaque. DSC measurements, showing a composition dependent Tsb{g} and a melting temperature depression, also indicate the miscibility achieved at the molecular level, about 50-100 A. By using the Hoffman-Weeks plot, a negative Flory-Huggins interaction parameter, chi = -1.10, is obtained for the PPTA anion/PEO molecular composites. An irregular spherulitic pattern and a reduced crystal size suggest that PPTA anion is intimately mixed with the amorphous PEO, both inter- and intra-spherulitically. Molecular composites exhibit not only an enhanced tensile strength and modulus, but also a greater fracture toughness, Ksb{IC}, e.g., an 80% increase at a 2 wt% PPTA anion addition. An enhanced tensile strength associated with a reduced crystallinity suggests that PPTA anion is the major contributor to the superior tensile properties instead of the crystalline phase. Upon addition of PPTA anion to PPrO, a slower relaxation rate and a better thermal stability are observed. Significant enhancement is found when the monovalent K salt is replaced with a divalent Ca salt. The molecular reinforcement achieved via ion-dipole interactions is more effective than the rigid filler effect obtained in the non-ionic PPTA/PPrO blend: e.g., a modulus enhancement of 814% vs. 286%, as compared with the value for PPrO. Two phase systems with microphase separation are developed since many

  3. Nanoparticle Ordering in Semicrystalline Polymers

    Science.gov (United States)

    Gimenez-Pinto, Vianney; Zhao, Dan; Kumar, Sanat

    One way to engineer the macroscopic properties of a crystalline polymer matrix is to place nanoparticles into them, but in an organized manner. We have recently found that NP organization can be controlled by varying the crystal growth rate. We develop a coarse-grained model to study this situation - in particular, we focus on the out-of-equilibrium dynamics of nanoparticles being pushed/engulfed by a solidification front depending on crystallization velocity vs. Particle engulfment occurs when vs is higher than a critical velocity vc. When vs is smaller than vc, particles are pushed by the crystallization front and organize in a 2-D plane. Even though most models for particle engulfment consider dynamic force equilibrium at vc, we show the system is not in equilibrium in this regime. Thus, we consider conditions for engulfment based on particle velocity with respect to crystal growth rate. Our results agree with experimental observations on anisotropic organization of nanoparticles in semicrystalline polymers driven by crystallization speed.

  4. Liquid Crystalline Graphene Oxide/PEDOT:PSS Self-Assembled 3D Architecture for Binder-Free Supercapacitor Electrodes

    OpenAIRE

    Islam, Md. Monirul; Chidembo, Alfred T.; Aboutalebi, Seyed Hamed; Cardillo, Dean; Liu, Hua Kun; Konstantinov, Konstantin; Dou, Shi Xue

    2014-01-01

    Binder-free self-assembled 3D architecture electrodes have been fabricated by a novel convenient method. Liquid crystalline graphene oxide was used as precursor to interact with poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in dispersion in order to form a conductive polymer entrapped, self-assembled layer-by-layer structure. This advanced network containing PEDOT:PSS enabled us to ascribe the superior electrochemical properties of particular graphene sheets. This layer...

  5. Liquid crystalline graphene oxide/PEDOT:PSS self-assembled 3D architecture for binder-free supercapacitor electrodes

    OpenAIRE

    Monirul eIslam; Alfred eChidembo; Hamed eAboutalebi; Dean eCardillo; Hua Kun Liu; Konstantin eKonstantinov; Shi Xue Dou

    2014-01-01

    Binder-free self-assembled 3D architecture electrodes have been fabricated by a novel convienient method. Liquid crystalline graphene oxide (LC GO) was used as precursor to interact with poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in dispersion in order to form a conductive polymer entrapped, self-assembled layer-by-layer structure. This advanced network containing PEDOT:PSS enabled us to ascribe the superior electrochemical properties of particular graphene sheets. T...

  6. Novel Elastomeric Membranes Developed for Polymer Electrolytes in Lithium Batteries

    Science.gov (United States)

    Tigelaar, Dean M.; Meador, Maryann B.; Kinder, James D.; Bennett, William R.

    2005-01-01

    Lithium-based polymer batteries for aerospace applications need to be highly conductive from -70 to 70 C. State-of-the-art polymer electrolytes are based on polyethylene oxide (PEO) because of the ability of its ether linkages to solvate lithium ions. Unfortunately, PEO has a tendency to form crystalline regions below 60 C, dramatically lowering conductivity below this temperature. PEO has acceptable ionic conductivities (10(exp -4) to 10(exp -3) S/cm) above 60 C, but it is not mechanically strong. The room-temperature conductivity of PEO can be increased by adding solvent or plasticizers, but this comes at the expense of thermal and mechanical stability. One of NASA Glenn Research Center s objectives in the Polymer Rechargeable System program (PERS) is to develop novel polymer electrolytes that are highly conductive at and below room temperature without added solvents or plasticizers.

  7. Polymer nanocomposites: polymer and particle dynamics

    KAUST Repository

    Kim, Daniel

    2012-01-01

    Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has been hypothesized that these unusual properties result from fast diffusion of the nanostructures in the host polymer, which facilitates polymer chain relaxation by constraint release and other processes. In this study, the effects of addition of sterically stabilized inorganic nanoparticles to entangled cis-1,4-polyisoprene and polydimethylsiloxane on the overall rheology of nanocomposites are discussed. In addition, insights about the relaxation of the host polymer chains and transport properties of nanoparticles in entangled polymer nanocomposites are presented. The nanoparticles are found to act as effective plasticizers for their entangled linear hosts, and below a critical, chemistry and molecular-weight dependent particle volume fraction, lead to reduced viscosity, glass transition temperature, number of entanglements, and polymer relaxation time. We also find that the particle motions in the polymer host are hyperdiffusive and at the nanoparticle length scale, the polymer host acts like a simple, ideal fluid and the composites\\' viscosity rises with increasing particle concentration. © 2012 The Royal Society of Chemistry.

  8. A flexible liquid crystal polymer MEMS pressure sensor array for fish-like underwater sensing

    Science.gov (United States)

    Kottapalli, A. G. P.; Asadnia, M.; Miao, J. M.; Barbastathis, G.; Triantafyllou, M. S.

    2012-11-01

    In order to perform underwater surveillance, autonomous underwater vehicles (AUVs) require flexible, light-weight, reliable and robust sensing systems that are capable of flow sensing and detecting underwater objects. Underwater animals like fish perform a similar task using an efficient and ubiquitous sensory system called a lateral-line constituting of an array of pressure-gradient sensors. We demonstrate here the development of arrays of polymer microelectromechanical systems (MEMS) pressure sensors which are flexible and can be readily mounted on curved surfaces of AUV bodies. An array of ten sensors with a footprint of 60 (L) mm × 25 (W) mm × 0.4 (H) mm is fabricated using liquid crystal polymer (LCP) as the sensing membrane material. The flow sensing and object detection capabilities of the array are illustrated with proof-of-concept experiments conducted in a water tunnel. The sensors demonstrate a pressure sensitivity of 14.3 μV Pa-1. A high resolution of 25 mm s-1 is achieved in water flow sensing. The sensors can passively sense underwater objects by transducing the pressure variations generated underwater by the movement of objects. The experimental results demonstrate the array’s ability to detect the velocity of underwater objects towed past by with high accuracy, and an average error of only 2.5%.

  9. Diketopyrrolopyrrole Polymers with Thienyl and Thiazolyl Linkers for Application in Field-Effect Transistors and Polymer Solar Cells.

    Science.gov (United States)

    Yu, Yaping; Wu, Yang; Zhang, Andong; Li, Cheng; Tang, Zheng; Ma, Wei; Wu, Yonggang; Li, Weiwei

    2016-11-09

    Conjugated polymers consisting of diketopyrrolopyrrole (DPP) units have been successfully applied in field-effect transistors (FETs) and polymer solar cells (PSCs), while most of the DPP polymers were designed as symmetric structures containing identical aromatic linkers. In this manuscript, we design a new asymmetric DPP polymer with varied aromatic linkers in the backbone for application in FETs and PSCs. The designation provides the chance to finely adjust the energy levels of conjugated polymers so as to influence the device performance. The asymmetric polymer exhibits highly crystalline properties, high hole mobilities of 3.05 cm(2) V(-1) s(-1) in FETs, and a high efficiency of 5.9% in PSCs with spectra response from 300 to 850 nm. Morphology investigation demonstrates that the asymmetric polymer has a large crystal domain in blended thin films, indicating that the solar cell performance can be further enhanced by optimizing the microphase separation. The study reveals that the asymmetric design via adjusting the aromatic linkers in DPP polymers is a useful route toward flexible electronic devices.

  10. Protective colloids and polylactic acid co-affecting the polymorphic crystal forms and crystallinity of indomethacin encapsulated in microspheres.

    Science.gov (United States)

    Lin, S Y; Chen, K S; Teng, H H

    1999-01-01

    The co-effect of protective colloids and polylactic acid (PLA) on the polymorphic crystal forms and crystallinity of indomethacin (IMC) in IMC-loaded PLA microspheres was investigated with differential scanning calorimetry, infrared spectroscopy and x-ray diffractometry, to evaluate the polymorphic crystal forms and crystallinity of IMC encapsulated in PLA microspheres. The surfactant, sodium dodecyl sulphate (SDS), was also used as a dispersing agent. The results indicate that the polymorphism and crystallinity of IMC encapsulated in IMC-loaded PLA microspheres was dependent on the type of protective colloid and PLA used. The amorphous state and alpha-form of IMC were found in the IMC-loaded PLA microspheres prepared using polysaccharide (pectin or beta-cyclodextrin) as a protective colloid or SDS as a dispersing agent. However, the amorphous and methylene chloride solvate of IMC seemed to exist in the IMC-loaded PLA microspheres prepared with the proteins (gelatin or albumin), synthetic cellulose derivative (methyl cellulose or hydroxylpropyl methylcellulose) or the synthetic nonionic polymer (polyvinyl alcohol, polyvinyl pyrrolidone or biosoluble polymer) as a protective colloid. PLA was found to express a certain crystallinity in microspheres and not be affected by the protective colloids, but it played a more important role in influencing the crystallization of IMC during microencapsulation than the protective colloids. No interaction occurred in the physical mixture of IMC and PLA, nor in the IMC-loaded PLA microspheres.

  11. Organic single crystals or crystalline micro/nanostructures: Preparation and field-effect transistor applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Organic single crystals hold great promise for the development of organic semiconductor materials,because they could reveal the intrinsic electronic properties of these materials,providing high-performance electronic devices and probing the structureproperty relationships.This article reviews the preparation methods for organic single crystals or crystalline micro/nanostructures,including vapor phase growth methods and solution-processed methods,and summarizes a few methods employed in the fabrication of field-effect transistors along with dozens of examples concerning both small molecules and polymers with high field-effect performance.

  12. Synthesis and Characterization of Storage Energy Materials Prepared from Nano-crystalline Cellulose/Polyethylene Glycol

    Institute of Scientific and Technical Information of China (English)

    Xiao Ping YUAN; En Yong DING

    2006-01-01

    This paper gives a brief report of the synthesis of a new kind of solid-solid phase change materials (SSPCMs), nano-crystalline cellulose/polyethylene glycol (NCC/PEG). These PCMs have very high ability for energy storage, and their enthalpies reach 103.8 J/g. They are composed of two parts, PEG as functional branches for energy storage, and NCC as skeleton. The flexible polymer PEG was grafted onto the surface of rigid powder of NCC by covalent bonds. The results of DSC, FT-IR were briefly introduced, and some comments were also given.

  13. Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

    OpenAIRE

    Abdullah Uzum; Masashi Kuriyama; Hiroyuki Kanda; Yutaka Kimura; Kenji Tanimoto; Hidehito Fukui; Taichiro Izumi; Tomitaro Harada; Seigo Ito

    2017-01-01

    Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm) was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fa...

  14. Synthesis and Characterization of Liquid Crystalline Poly((N-acylethyleneimine)s.

    Science.gov (United States)

    1986-10-01

    8217%-,% , . . . % .% . . " ’% ’ # ./ / ." ’ z ’%’z . ’’ .’ ’ ’ 4. Ethyl-5-(4-phenylphenoxy)Valerate (BiPh-4-COO~t) 4- Phenylphenol (8g, 0.04 mol) and 1.656g (0.04...vacuum. The sodium salt of 4- phenylphenol was put Into 120 al of dried dimethylformamide and 8.5 .l (0.054 mol) of ethyl-5-bromovalerate and l.4g (10...that poly(BiPh-4-Oxz) is crystalline. This is not an unexpected result. The insertion of 4- phenylphenol as side group in polymers before, did give

  15. Crystalline fibres of a covalent organic framework through bottom-up microfluidic synthesis.

    Science.gov (United States)

    Rodríguez-San-Miguel, David; Abrishamkar, Afshin; Navarro, Jorge A R; Rodriguez-Trujillo, Romen; Amabilino, David B; Mas-Ballesté, Ruben; Zamora, Félix; Puigmartí-Luis, Josep

    2016-07-28

    A microfluidic chip has been used to prepare fibres of a porous polymer with high structural order, setting a precedent for the generation of a wide variety of materials using this reagent mixing approach that provides unique materials not accessible easily through bulk processes. The reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in acetic acid under continuous microfluidic flow conditions leads to the formation of a highly crystalline and porous covalent organic framework (hereafter denoted as MF-COF-1), consisting of fibrillar micro-structures, which have mechanical stability that allows for direct drawing of objects on a surface.

  16. Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group

    Directory of Open Access Journals (Sweden)

    Kohsuke Kawabata

    2009-01-01

    Full Text Available Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers.

  17. Crystalline structures, thermal properties and crystallizing mechanism of polyamide 6 nanotubes in confined space

    Science.gov (United States)

    Li, Xiaoru; Peng, Zhi; Yang, Chao; Han, Ping; Song, Guojun; Cong, Longliang

    2016-09-01

    The polyamide 6 (PA6) nanotubes were prepared by infiltrating the anodic aluminum oxide templates with polymer solution. Crystalline regions in the nanotube walls were detected by high-resolution transmission electron microscopy (HRTEM). X-ray diffraction (XRD), Fast Fourier Transform (FFT) and differential scanning calorimetry (DSC) techniques were employed to investigate crystallization, crystal faces and thermodynamics. It was found that the crystals were transformed from α-form in bulk to γ-form in nanotubes. It was made a detailed analysis in this article. Moreover, schematic diagram for the crystallizing mechanism of PA6 nanotubes was given to explain PA6 molecules how to crystallize in the nano-pores.

  18. Alignment engineering in liquid crystalline elastomers: Free-form microstructures with multiple functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Hao; Cerretti, Giacomo; Wiersma, Diederik S., E-mail: camilla.parmeggiani@lens.unifi.it, E-mail: wiersma@lens.unifi.it [European Laboratory for Non Linear Spectroscopy (LENS), University of Florence, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Wasylczyk, Piotr [European Laboratory for Non Linear Spectroscopy (LENS), University of Florence, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Faculty of Physics, Institute of Experimental Physics, University of Warsaw, ul. Hoza 69, Warszawa 00-681 (Poland); Martella, Daniele [European Laboratory for Non Linear Spectroscopy (LENS), University of Florence, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Dipartimento di Chimica “Ugo Schiff,” University of Florence, via della Lastruccia 3-13, 50019 Sesto Fiorentino (Italy); Parmeggiani, Camilla, E-mail: camilla.parmeggiani@lens.unifi.it, E-mail: wiersma@lens.unifi.it [European Laboratory for Non Linear Spectroscopy (LENS), University of Florence, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); CNR-INO, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy)

    2015-03-16

    We report a method to fabricate polymer microstructures with local control over the molecular orientation. Alignment control is achieved on molecular level in a structure of arbitrary form that can be from 1 to 100 μm in size, by fixing the local boundary conditions with micro-grating patterns. The method makes use of two-photon polymerization (Direct Laser Writing) and is demonstrated specifically in liquid-crystalline elastomers. This concept allows for the realization of free-form polymeric structures with multiple functionalities which are not possible to realize with existing techniques and which can be locally controlled by light in the micrometer scale.

  19. Twinning of Polymer Crystals Suppressed by Entropy

    Directory of Open Access Journals (Sweden)

    Nikos Ch. Karayiannis

    2014-09-01

    Full Text Available We propose an entropic argument as partial explanation of the observed scarcity of twinned structures in crystalline samples of synthetic organic polymeric materials. Polymeric molecules possess a much larger number of conformational degrees of freedom than low molecular weight substances. The preferred conformations of polymer chains in the bulk of a single crystal are often incompatible with the conformations imposed by the symmetry of a growth twin, both at the composition surfaces and in the twin axis. We calculate the differences in conformational entropy between chains in single crystals and chains in twinned crystals, and find that the reduction in chain conformational entropy in the twin is sufficient to make the single crystal the stable thermodynamic phase. The formation of cyclic twins in molecular dynamics simulations of chains of hard spheres must thus be attributed to kinetic factors. In more realistic polymers this entropic contribution to the free energy can be canceled or dominated by nonbonded and torsional energetics.

  20. Donor-hydrogen complexes in crystalline silicon

    NARCIS (Netherlands)

    Liang, Z.N.; Niesen, L; Haas, C; Denteneer, P.J.H.

    1996-01-01

    Experimental results are presented on the study of Sb-H complexes in crystalline silicon, employing Sb-119 --> Sn-119 source Mossbauer spectroscopy and a low-energy H implantation technique. In addition to a visible component, we observe a large decrease of the Mossbauer intensity associated with

  1. Smeared gap equations in crystalline color superconductivity

    CERN Document Server

    Ruggieri, M

    2006-01-01

    In the framework of HDET, we discuss an averaging procedure of the NJL quark-quark interaction lagrangian, treated in the mean field approximation, for the two flavor LOFF phase of QCD. This procedure gives results which are valid in domains where Ginzburg-Landau results may be questionable. We compute and compare the free energy for different LOFF crystalline structures.

  2. Crystalline amino acids and nitrogen emission

    NARCIS (Netherlands)

    Verstegen, M.W.A.; Jongbloed, A.W.

    2003-01-01

    Reductions in dietary protein level and supplementation with certain crystalline amino acids is a well-established method of formulating diets to achieve a more ideal amino acid pattern and to reduce nitrogen excretion. Up to 35% reduction in nitrogen excretion may be achieved by supplementing pig

  3. Quasi-crystalline geometry for architectural structures

    DEFF Research Database (Denmark)

    Wester, Ture; Weinzieri, Barbara

    The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells with fivefold symmetry in 3D space...

  4. Crystalline damage development during martensitic transformations

    NARCIS (Netherlands)

    Suiker, A.S.J.; Turteltaub, S.R.

    2006-01-01

    A recently developed thermo-mechanical model [1] is presented that can be used to simulate the interactions between martensitic phase transformations and crystalline damage growth at the austenitic grain level. Subgrain information is included in the model via the crystallographic theory of martensi

  5. Donor-hydrogen complexes in crystalline silicon

    NARCIS (Netherlands)

    Liang, Z.N.; Niesen, L; Haas, C; Denteneer, P.J.H.

    1996-01-01

    Experimental results are presented on the study of Sb-H complexes in crystalline silicon, employing Sb-119 --> Sn-119 source Mossbauer spectroscopy and a low-energy H implantation technique. In addition to a visible component, we observe a large decrease of the Mossbauer intensity associated with th

  6. Topological crystalline insulator SnTe nanoribbons

    Science.gov (United States)

    Dahal, Bishnu R.; Dulal, Rajendra P.; Pegg, Ian L.; Philip, John

    2017-03-01

    Topological crystalline insulators are systems in which a band inversion that is protected by crystalline mirror symmetry gives rise to nontrivial topological surface states. SnTe is a topological crystalline insulator. It exhibits p-type conductivity due to Sn vacancies and Te antisites, which leads to high carrier density in the bulk. Thus growth of high quality SnTe is a prerequisite for understanding the topological crystalline insulating behavior. We have grown SnTe nanoribbons using a solution method. The width of the SnTe ribbons varies from 500 nm to 2 μm. They exhibit rock salt crystal structure with a lattice parameter of 6.32 Å. The solution method that we have adapted uses low temperature, so the Sn vacancies can be controlled. The solution grown SnTe nanoribbons exhibit strong semiconducting behavior with an activation energy of 240 meV. This activation energy matches with the calculated band gap for SnTe with a lattice parameter of 6.32 Å, which is higher than that reported for bulk SnTe. The higher activation energy makes the thermal excitation of bulk charges very difficult on the surface. As a result, the topological surfaces will be free from the disturbance caused by the thermal excitations

  7. Crystalline amino acids and nitrogen emission

    NARCIS (Netherlands)

    Verstegen, M.W.A.; Jongbloed, A.W.

    2003-01-01

    Reductions in dietary protein level and supplementation with certain crystalline amino acids is a well-established method of formulating diets to achieve a more ideal amino acid pattern and to reduce nitrogen excretion. Up to 35% reduction in nitrogen excretion may be achieved by supplementing pig d

  8. Evidence for variable crystallinity in bivalve shells

    Science.gov (United States)

    Jacob, D. E.; Wehrmeister, U.

    2012-04-01

    Bivalve shells are used as important palaeoclimate proxy archives and monitor regional climate variations. The shells mostly exist of two crystalline polymorphic phases of calcium carbonate calcite (rombohedric) and aragonite (orthorhombic). Calcite is the most stable polymorph at standard conditions, whereas vaterite (hexagonal) is the least stable and only rarely found in these structures. Shells are characterized by organized structures and several micro architectures of mollusc shell structures have been identified: Nacre shows different types: columnar and bricked forms and consists of composite inorganic- organic at the nano-scale. They are well known to display a "brick and mortar" structure. By AFM and FIB/TEM methods it could be shown, that its nanostructure consists of the structures in the range of 50 - 100 nm [1, 2]. These structures are vesicles, consisting of CaCO3 and are individually coated by a membrane. Most probably, the mantle epithelian cells of the bivalve extrude CaCO3 vesicles. By Raman spectroscopic investigations the crystalline CaCO3 polymorphs calcite, aragonite and vaterite, as well as ACC were determined. For some species (Diplodon chilensis patagonicus, Hyriopsis cumingii) pure ACC (i.e. not intermingled with a crystalline phase) could be identified. The presence of an amorphous phase is generally deduced from the lack of definite lattice modes, whereas a broad Raman band in this region is to observe. In most of the cultured pearls (Pinctada maxima and genus Hyriopsis) the ν1-Raman band of ACC clearly displays an asymmetric shape and splits into two different bands according to a nanocrystalline and an amorphous fraction. The FWHMs of most of the crystalline fractions are too high for well crystallized materials and support the assumption of nanocrystalline calcium carbonate polymorph clusters in ACC. They are primarily composed of amorphous calcium carbonate (ACC) which is later transformed into a crystalline modification [3

  9. Growing perovskite into polymers for easy-processable optoelectronic devices

    Science.gov (United States)

    Masi, Sofia; Colella, Silvia; Listorti, Andrea; Roiati, Vittoria; Liscio, Andrea; Palermo, Vincenzo; Rizzo, Aurora; Gigli, Giuseppe

    2015-01-01

    Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processability of polymers, providing a tool to control film quality and material crystallinity. We verify that the employed semiconducting polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), controls the self-assembly of CH3NH3PbI3 (MAPbI3) crystalline domains and favors the deposition of a very smooth and homogenous layer in one straightforward step. This idea offers a new paradigm for the implementation of polymer/perovskite nanocomposites towards versatile optoelectronic devices combined with the feasibility of mass production. As a proof-of-concept we propose the application of such nanocomposite in polymer solar cell architecture, demonstrating a power conversion efficiency up to 3%, to date the highest reported for MEH-PPV. On-purpose designed polymers are expected to suit the nanocomposite properties for the integration in diverse optoelectronic devices via facile processing condition.

  10. MOLECULAR IMPRINTED POLYMERS--Novel Polymer Adsorbents

    Institute of Scientific and Technical Information of China (English)

    LI Haitao; XU Mancai; SHI Zuoqing; HE Binglin

    2001-01-01

    Molecular imprinted polymers (MIPs) are novel functional polymer materials and known as specific adsorbents for the template molecules. These novel functional polymers have promised potential applications in racemic resolution, sensor, chromatography, adsorptive separation and other fields. This review exhibits the approach for preparing MIPs, the features of MIPs obtained by different routes and the characteristics of adsorptive separations with MIPs. The molecular recognition mechanism and the idea of the present possibilities and limitations of molecular imprinting polymerization are discussed as well.

  11. Polymer electrolytes composed of lithium tetrakis(pentafluorobenzenethiolato) borate and poly(fluoroalkylcarbon)s

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Takahiro; Konno, Akinori; Fujinami, Tatsuo [Department of Materials Science and Chemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8561 (Japan)

    2005-08-26

    Lithium ion conducting polymer electrolytes were prepared by mixing insoluble lithium tetrakis(pentafluorobenzenethiolato) borate (LiTPSB) with poly(vinylidene fluoride) (PVDF) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Their films were prepared by hot pressing and are investigated for ionic conductivity and thermal properties. LiTPSB is insoluble in PVDF. Ionic conductivity was largely dependent on the salt content for LiTPSB-PVDF composite polymer electrolytes, and exhibited higher ionic conductivity than homogeneous LiTFSI-PVDF based polymer electrolytes. Melting point and crystallinity of PVDF were independent on LiTPSB content, resulting in no difference for melting point and crystallinity between pure PVDF and LiTPSB-PVDF. Ionic conductivity was effectively improved by incorporation of 18-crown-6 or kryptofix222 for LiTPSB-PVDF based polymer electrolytes. (author)

  12. Band gap engineering in polymers through chemical doping and applied mechanical strain

    Science.gov (United States)

    Lanzillo, Nicholas A.; Breneman, Curt M.

    2016-08-01

    We report simulations based on density functional theory and many-body perturbation theory exploring the band gaps of common crystalline polymers including polyethylene, polypropylene and polystyrene. Our reported band gaps of 8.6 eV for single-chain polyethylene and 9.1 eV for bulk crystalline polyethylene are in excellent agreement with experiment. The effects of chemical doping along the polymer backbone and side-groups are explored, and the use mechanical strain as a means to modify the band gaps of these polymers over a range of several eV while leaving the dielectric constant unchanged is discussed. This work highlights some of the opportunities available to engineer the electronic properties of polymers with wide-reaching implications for polymeric dielectric materials used for capacitive energy storage.

  13. Influence of processing and intrinsic polymer parameters on photochemical stability of polythiophene thin films

    DEFF Research Database (Denmark)

    Vesterager Madsen, Morten; Tromholt, Thomas; Böttiger, Arvid P.L.

    2012-01-01

    Intrinsic polymer parameters such as regio-regularity, molecular weight, and crystallinity play an important role when studying polymer stability. 18 different batches of poly-3-hexyl-thiophene (P3HT) were degraded in a solar simulator (AM1.5G, 1000 W/m2) and the degradation kinetics were monitored......-to-tail connected thiophene units. Annealing was found to relax the P3HT films and increase conjugation length and, in turn, increase stability observed as a delayed spectral blueshift caused by photochemical degradation. Crystallinity was found to play a minor role in terms of stability. Oxygen diffusion and light...... shielding effects were shown to have a negligible effect on the photochemical degradation rate. The results obtained in this work advance the understanding of polymer stability and will help improve the design of materials used for polymer solar cells resulting in longer lifetimes, which will push...

  14. Stability and Degradation of Organic and Polymer Solar Cells

    DEFF Research Database (Denmark)

    Organic photovoltaics (OPV) are a new generation of solar cells with the potential to offer very short energy pay back times, mechanical flexibility and significantly lower production costs compared to traditional crystalline photovoltaic systems. A weakness of OPV is their comparative instability...... during operation and this is a critical area of research towards the successful development and commercialization of these 3rd generation solar cells. Covering both small molecule and polymer solar cells, Stability and Degradation of Organic and Polymer Solar Cells summarizes the state of the art...

  15. Orienting semi-conducting π-conjugated polymers.

    Science.gov (United States)

    Brinkmann, Martin; Hartmann, Lucia; Biniek, Laure; Tremel, Kim; Kayunkid, Navaphun

    2014-01-01

    The present review focuses on the recent progress made in thin film orientation of semi-conducting polymers with particular emphasis on methods using epitaxy and shear forces. The main results reported in this review deal with regioregular poly(3-alkylthiophene)s and poly(dialkylfluorenes). Correlations existing between processing conditions, macromolecular parameters and the resulting structures formed in thin films are underlined. It is shown that epitaxial orientation of semi-conducting polymers can generate a large palette of semi-crystalline and nanostructured morphologies by a subtle choice of the orienting substrates and growth conditions.

  16. Polymer Functionalized Nanoparticles in Polymer Nanocomposites

    Science.gov (United States)

    Jayaraman, Arthi

    2013-03-01

    Significant interest has grown around the ability to control spatial arrangement of nanoparticles in a polymer nanocomposite to engineer materials with target properties. Past work has shown that one could achieve controlled assembly of nanoparticles in the polymer matrix by functionalizing nanoparticle surfaces with homopolymers. This talk will focus on our recent work using Polymer Reference Interaction Site Model (PRISM) theory and Monte Carlo simulations and GPU-based molecular dynamics simulations to specifically understand how heterogeneity in the polymer functionalization in the form of a) copolymers with varying monomer chemistry and monomer sequence, and b) polydispersity in homopolymer grafts can tune effective interactions between functionalized nanoparticles, and the assembly of functionalized nanoparticles.

  17. Conducting polymer materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2003-01-01

    Full Text Available Conducting polymers represent a very interesting group of polymer materials Investigation of the synthesis, structure and properties of these materials has been the subject of considerable research efforts in the last twenty years. A short presentating of newer results obtained by investigating of the synthesis, structure and properties of two basic groups of conducting polymers: a conducting polymers the conductivity of which is the result of their molecular structure, and b conducting polymer composites (EPC, is given in this paper. The applications and future development of this group of polymer materials is also discussed.

  18. Effects of Confinement on Microstructure and Charge Transport in High Performance Semicrystalline Polymer Semiconductors

    KAUST Repository

    Himmelberger, Scott

    2012-11-23

    The film thickness of one of the most crystalline and highest performing polymer semiconductors, poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene) (PBTTT), is varied in order to determine the effects of interfaces and confinement on the microstructure and performance in organic field effect transistors (OFETs). Crystalline texture and overall film crystallinity are found to depend strongly on film thickness and thermal processing. The angular distribution of crystallites narrows upon both a decrease in film thickness and thermal annealing. These changes in the film microstructure are paired with thin-film transistor characterization and shown to be directly correlated with variations in charge carrier mobility. Charge transport is shown to be governed by film crystallinity in films below 20 nm and by crystalline orientation for thicker films. An optimal thickness is found for PBTTT at which the mobility is maximized in unannealed films and where mobility reaches a plateau at its highest value for annealed films. The effects of confinement on the morphology and charge transport properties of poly(2,5-bis(3-tetradecylthiophen-2-yl) thieno[3,2-b]thiophene) (PBTTT) are studied using quantitative X-ray diffraction and field-effect transistor measurements. Polymer crystallinity is found to limit charge transport in the thinnest films while crystalline texture and intergrain connectivity modulate carrier mobility in thicker films. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Polyurethanes from the crystalline prepolymers resistant to abrasive wear

    Directory of Open Access Journals (Sweden)

    Domańska Agata

    2014-12-01

    Full Text Available The research aimed at the selection of polyurethanes synthesized from poly(tetramethylene ether glycol (PTMEG, as well as from two different isocyanates 4,4′-methylenebis(cyclohexylisocyanate (HMDI and 4.4′-methylenebis(phenyl isocyanate (MDI in order to obtain polyurethane with increased resistance to abrasive wear and degradation for bio-medical application. Polyurethanes were fabricated from crystalline prepolymers extended by water. The paper presents preliminary results on polyurethane surface wettability, friction coefficient for different couples of the co-working materials such as polyurethane-polyurethane, polyurethane-titanium alloy, polyurethane-alumina, in comparison to commonly used polyethylene-titanium alloy. Shear strength of polyurethane-alumina joint, as well as viscosity of prepolymers were also measured. The values of friction coefficient were compared to literature data on commercially available polyurethane with the trade name Pellethane. Polyurethanes obtained are characterized by low abrasive wear and low friction coefficient in couple with the titanium alloy, what makes them attractive as possible components of ceramic-polymer endoprosthesis joints.

  20. Characterization and use of crystalline bacterial cell surface layers

    Science.gov (United States)

    Sleytr, Uwe B.; Sára, Margit; Pum, Dietmar; Schuster, Bernhard

    2001-10-01

    Crystalline bacterial cell surface layers (S-layers) are one of the most common outermost cell envelope components of prokaryotic organisms (archaea and bacteria). S-layers are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. S-layers as the most abundant of prokaryotic cellular proteins are appealing model systems for studying the structure, synthesis, genetics, assembly and function of proteinaceous supramolecular structures. The wealth of information existing on the general principle of S-layers have revealed a broad application potential. The most relevant features exploited in applied S-layer research are: (i) pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes; (ii) functional groups on the surface and in the pores are aligned in well-defined positions and orientations and accessible for chemical modifications and binding functional molecules in very precise fashion; (iii) isolated S-layer subunits from a variety of organisms are capable of recrystallizing as closed monolayers onto solid supports (e.g., metals, polymers, silicon wafers) at the air-water interface, on lipid films or onto the surface of liposomes; (iv) functional domains can be incorporated in S-layer proteins by genetic engineering. Thus, S-layer technologies particularly provide new approaches for biotechnology, biomimetics, molecular nanotechnology, nanopatterning of surfaces and formation of ordered arrays of metal clusters or nanoparticles as required for nanoelectronics.

  1. Highly Crystalline Nanoparticle Suspensions for Low-Temperature Processing of TiO2 Thin Films.

    Science.gov (United States)

    Watté, Jonathan; Lommens, Petra; Pollefeyt, Glenn; Meire, Mieke; De Buysser, Klaartje; Van Driessche, Isabel

    2016-05-25

    In this work, we present preparation and stabilization methods for highly crystalline TiO2 nanoparticle suspensions for the successful deposition of transparent, photocatalytically active TiO2 thin films toward the degradation of organic pollutants by a low temperature deposition method. A proof-of-concept is provided wherein stable, aqueous TiO2 suspensions are deposited on glass substrates. Even if the processing temperature is lowered to 150-200 °C, the subsequent heat treatment provides transparent and photocatalytically active titania thin layers. Because all precursor solutions are water-based, this method provides an energy-efficient, sustainable, and environmentally friendly synthesis route. The high load in crystalline titania particles obtained after microwave heating opens up the possibility to produce thin coatings by low temperature processing, as a conventional crystallization procedure is in this case superfluous. The impact of the precursor chemistry in Ti(4+)-peroxo solutions, containing imino-diacetic acid as a complexing ligand and different bases to promote complexation was studied as a function of pH, reaction time and temperature. The nanocrystal formation was followed in terms of colloidal stability, crystallinity and particle size. Combined data from Raman and infrared spectroscopy, confirmed that stable titanium precursors could be obtained at pH levels ranging from 2 to 11. A maximum amount of 50.7% crystallinity was achieved, which is one of the highest reported amounts of anatase nanoparticles that are suspendable in stable aqueous titania suspensions. Decoloring of methylene blue solutions by precipitated nanosized powders from the TiO2 suspensions proves their photocatalytic properties toward degradation of organic materials, a key requisite for further processing. This synthesis method proves that the deposition of highly crystalline anatase suspensions is a valid route for the production of photocatalytically active, transparent

  2. Electrospun PVdF-PVC nanofibrous polymer electrolytes for polymer lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhong Zheng [Key Laboratory of Environmentally Friendly Chemistry and Applications of Minister of Education, College of Chemistry, Xiangtan University, Xiangtan 411105 (China); Cao Qi, E-mail: wjcaoqi@163.com [Key Laboratory of Environmentally Friendly Chemistry and Applications of Minister of Education, College of Chemistry, Xiangtan University, Xiangtan 411105 (China); Jing Bo; Wang Xianyou; Li Xiaoyun; Deng Huayang [Key Laboratory of Environmentally Friendly Chemistry and Applications of Minister of Education, College of Chemistry, Xiangtan University, Xiangtan 411105 (China)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer The nanofibrous polymer electrolytes based on PVdF-PVC (8:2, w/w) prepared by electrospinning have an ionic conductivity of 2.25 Multiplication-Sign 10{sup -3} S cm{sup -1} at 25 Degree-Sign C. Black-Right-Pointing-Pointer The nanofibrous polymer electrolytes presented a good electrochemical stability up to 5.1 V (vs. Li/Li{sup +}). Black-Right-Pointing-Pointer The nanofibrous polymer electrolytes showed a very good charge/discharge and cycling performance. - Abstract: Nanofibrous membranes based on Poly (vinyl difluoride) (PVdF)-Poly (vinyl chloride) (PVC) (8:2, w/w) were prepared by electrospinning and then they were soaked in a liquid electrolyte to form polymer electrolytes (PEs). The morphology, thermal stability, function groups and crystallinity of the electrospun membranes were characterized by scanning electron microscope (SEM), thermal analysis (TG), Fourier transform infrared spectra (FT-IR) and differential scanning calorimetry (DSC), respectively. It was found that both electrolyte uptake and ionic conductivity of the composite PEs increased with the addition of PVC. The composite PVdF-PVC PEs had a high ionic conductivity up to 2.25 Multiplication-Sign 10{sup -3} S cm{sup -1} at 25 Degree-Sign C. These results showed that nanofibrous PEs based on PVdF-PVC were of great potential application in polymer lithium-ion batteries.

  3. Characterization of Piezoelectric Ceramic-Polymer Composites for Ultrasonic Sensor Applications

    Science.gov (United States)

    Jung, Kyung Keun; Park, Sang Hyoun; Yoo, Kwang Soo; Ko, Hyun Phill; Yoon, Seok Jin

    The piezoelectric ceramic-polymer composites were prepared by Pb(Zr0.52Ti0.48)O3 (PZT)-based ceramics with high piezoelectricity and electromechanical coupling factor and the polyvinylidene fluoride (PVdF) polymer with high acoustic impedance. The composites with 0-3 connectivity type were fabricated by hot pressing and tape casting methods. Their crystallinity, microstructure, dielectric, and piezoelectric properties were systematically evaluated.

  4. Morphology and conductivity of in-situ PEO-LiClO4-TiO2 composite polymer electrolyte

    Institute of Scientific and Technical Information of China (English)

    PAN Chun-yue; FENG Qing; WANG Li-jun; ZHANG Qian; CHAO Meng

    2007-01-01

    PEO-LiClO4-TiO2 composite polymer electrolyte films were prepared. TiO2 was formed directly in matrix by hydrolysis and condensation reaction of tetrabutyl titanate. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry, scanning electron microscopy, atom force microscopy and alternating current impedance spectroscopy, respectively. The glass transition temperature and the crystallinity of composite polymer electrolytes are decreased compared with those of PEO-LiClO4 polymer electrolyte film. The results show that TiO2 particles are uniformly dispersed in PEO-LiClO4-5%TiO2 composite polymer electrolyte film. The maximal conductivity of 5.5×10-5 S/cm at 20 ℃ of PEO-LiClO4-TiO2 film is obtained at 5% mass fraction of TiO2.

  5. Thermal conductivity and multiferroics of electroactive polymers and polymer composites

    Science.gov (United States)

    Jin, Jiezhu

    /m˙K, greatly affected by the phonon-phonon scattering and phonon boundary scattering. When the films are thicker than 130 nm, heat capacity also plays an important role in thermal conduction in polyaniline. The same technique is extended to measure the electrical and thermal conductivity of 55 nm thick polyaniline thin films doped with different levels of camphorsulfonic acid. Results indicate that the effect of the doping level (camphorsulfonic acid/polyaniline ratio) is more pronounced on electrical conductivity than on thermal conductivity, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% doping level, polyaniline thin film exhibits the maximum electrical and thermal conductivity due to the formation of mostly delocalized polaron structures. It is suggested that polarons are the charge carriers responsible for the electrical conduction, while phonons play a dominant role in the heat conduction in doped polyaniline thin films. Multiferroic materials combine unusual elastic, magnetic and electric properties, and have promising applications in many areas, such as sensors, transducers and read/write memory devices. For strain-mediated multiferroic ME composites, their ME effect are generated as a product property of the piezoelectric phase and magnetostrictive phase. In this dissertation, new multiferroic composites are developed and presented. One of them is based on chain-end cross-linked ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE). With a low dc bias magnetic field, the ME coefficient of this composite is 17.7 V/cm Oe at non-resonance and 383 V/cm Oe at resonance, well above the reported ME voltage coefficient of polymer based ME composite in current literature. ME composite based on poly(vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP) are also developed in this dissertation. Crystalline beta phase structure in P(VDF-HFP) is produced by uniaxially stretching of pre-melted and quenched films

  6. Molecular weaving via surface-templated epitaxy of crystalline coordination networks.

    Science.gov (United States)

    Wang, Zhengbang; Błaszczyk, Alfred; Fuhr, Olaf; Heissler, Stefan; Wöll, Christof; Mayor, Marcel

    2017-02-01

    One of the dream reactions in polymer chemistry is the bottom-up, self-assembled synthesis of polymer fabrics, with interwoven, one-dimensional fibres of monomolecular thickness forming planar pieces of textiles. We have made a major step towards realizing this goal by assembling sophisticated, quadritopic linkers into surface-mounted metal-organic frameworks. By sandwiching these quadritopic linkers between sacrificial metal-organic framework thin films, we obtained multi-heteroepitaxial, crystalline systems. In a next step, Glaser-Hay coupling of triple bonds in the quadritopic linkers yields linear, interwoven polymer chains. X-ray diffraction studies revealed that this topochemical reaction leaves the MOF backbone completely intact. After removing the metal ions, the textile sheets can be transferred onto different supports and imaged using scanning electron microscopy and atomic-force microscopy. The individual polymer strands forming the two-dimensional textiles have lengths on the order of 200 nm, as evidenced by atomic-force microscopy images recorded from the disassembled textiles.

  7. The equilibrium theory of inhomogeneous polymers (international series of monographs on physics)

    CERN Document Server

    Fredrickson, Glenn

    2013-01-01

    The Equilibrium Theory of Inhomogeneous Polymers provides an introduction to the field-theoretic methods and computer simulation techniques that are used in the design of structured polymeric fluids. By such methods, the principles that dictate equilibrium self-assembly in systems ranging from block and graft copolymers, to polyelectrolytes, liquid crystalline polymers, and polymer nanocomposites can be established. Building on an introductory discussion of single-polymer statistical mechanics, the book provides a detailed treatment of analytical and numerical techniques for addressing the conformational properties of polymers subjected to spatially-varying potential fields. This problem is shown to be central to the field-theoretic description of interacting polymeric fluids, and models for a number of important polymer systems are elaborated. Chapter 5 serves to unify and expound the topic of self-consistent field theory, which is a collection of analytical and numerical techniques for obtaining solutions o...

  8. Renforcement des polymères semi-cristallins

    OpenAIRE

    Corte, Laurent

    2006-01-01

    The impact resistance of semi-crystalline polymers is greatly improved by dispersing (sub)micronic particles that cavitate and induce the extensive plastic deformation of the matrix rather than its brittle failure. We were concerned with several aspects of this phenomenon through the study of toughened polyamide systems. We show that nanostructured particles of block copolymers yield remarkable toughening without the loss in rigidity that is obtained with rubber particles. Furthermore, the st...

  9. Some LCP Decompositions of Multistage Interconnection Networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Some useful layered cross product decompositons are derived both for general bit permutation networks and for(2n-1)-stage multistage interconnection networks. Several issues in related works are clarified and the rearrangeability of some interesting networks are considered. In particular, the rearrangeability of one class of networks is formulated as a new type of combinatorial design problmes.

  10. Polymer Fluid Dynamics.

    Science.gov (United States)

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  11. Polymer composites containing nanotubes

    Science.gov (United States)

    Bley, Richard A. (Inventor)

    2008-01-01

    The present invention relates to polymer composite materials containing carbon nanotubes, particularly to those containing singled-walled nanotubes. The invention provides a polymer composite comprising one or more base polymers, one or more functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers and carbon nanotubes. The invention also relates to functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers, particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having side chain functionalization, and more particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having olefin side chains and alkyl epoxy side chains. The invention further relates to methods of making polymer composites comprising carbon nanotubes.

  12. Introduction to Polymer Chemistry.

    Science.gov (United States)

    Harris, Frank W.

    1981-01-01

    Reviews the physical and chemical properties of polymers and the two major methods of polymer synthesis: addition (chain, chain-growth, or chain-reaction), and condensation (step-growth or step-reaction) polymerization. (JN)

  13. Shaped Ni nanoparticles with an unconventional hcp crystalline structure.

    Science.gov (United States)

    Kim, Chanyeon; Kim, Cheonghee; Lee, Kangtaek; Lee, Hyunjoo

    2014-06-18

    Hourglass-shaped Ni nanoparticles were synthesized with a hexagonal close packed (hcp) structure. The unconventional crystalline structure could be stabilized by intensive utilization of hexadecylamine. The dense organic layer on the surface protected the meta-stable crystalline structure.

  14. Investigation on poly (vinylidene fluoride) based gel polymer electrolytes

    Indian Academy of Sciences (India)

    S Rajendran; P Sivakumar; Ravi Shanker Babu

    2006-12-01

    An investigation is carried out on gel polymer electrolytes consisting of poly (vinylidene fluoride) (PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate (LiCF3SO3) as salts and mixture of ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. Polymer thin films were prepared by solvent casting technique and the obtained films were subjected to different characterizations, to confirm their structure, complexation and thermal changes. X-ray diffraction revealed that the salts and plasticizers disrupted the crystalline nature of PVdF based polymer electrolytes and converted them into an amorphous phase. TG/DTA studies showed the thermal stability of the polymer electrolytes. The role of interaction between polymer hosts on conductivity is discussed using the results of a.c. impedance studies. Room temperature (28°C) conductivity of 2.786 × 10-3 Scm-1 was observed in PVdF (24)–EC/PC (68)–LiCF3SO3 (2)/LiClO4 (6) polymer system.

  15. Controlled Growth of Metal-Organic Frameworks on Polymer Brushes.

    Science.gov (United States)

    Hou, Liman; Zhou, Mingdong; Dong, Xiaozhe; Wang, Lei; Xie, Zhigang; Dong, Dewen; Zhang, Ning

    2017-08-17

    Polymer brushes are for the first time used to induce the synthesis of metal-organic frameworks (MOFs). The semi-fixed polymer chains provide a confined environment, which allows a mild growth of MOFs in between polymer chains to give surface-attached spherical MOF nanoparticles, in contrast to the larger MOF cubes/plates formed simultaneously in solution. Polymer brushes bearing carboxylate acid functionalities are indispensable for the formation of surface bound MOFs, while no MOF nanoparticles are observed on neutral polymer brushes. Characterization of the resultant MOF/polymer brushes hybrid film indicates the formation of crystalline MOF structure. The dimension of surface-attached MOFs can be fine-tuned from 20 nm to 1.4 μm simply by varying the structural parameter of polymer brushes and the nucleation duration. The method is not only applicable to the synthesis of MOF-5 and MIL-125, but shows great potential for the preparation of other surface-attached MOFs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF POLYMERS WITH PHYSICAL CROSSLINKS

    Institute of Scientific and Technical Information of China (English)

    Mao Xu; Feng-kui Li

    1999-01-01

    The shape memory effect of polymers was investigated for the purpose of improving the processing conditions of their preparation and broadening the list of polymers for shape memory applications. Emphasis was put on the possibility of using polymers with physical crosslinks as shape memory materials and their structure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymers were used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoverable strain and high final recovery rate. The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks. As only physical crosslinks are introduced, all conventional processing techniques for thermal plastics can be used, and the materials become easily reusable. The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect. The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.

  17. Dendritic polyurea polymers.

    Science.gov (United States)

    Tuerp, David; Bruchmann, Bernd

    2015-01-01

    Dendritic polymers, subsuming dendrimers as well as hyperbranched or highly branched polymers are well established in the field of polymer chemistry. This review article focuses on urea based dendritic polymers and summarizes their synthetic routes through both isocyanate and isocyanate-free processes. Furthermore, this article highlights applications where dendritic polyureas show their specific chemical and physical potential. For these purposes scientific publications as well as patent literature are investigated to generate a comprehensive overview on this topic.

  18. Antimicrobial Modifications of Polymers

    OpenAIRE

    Sedlarik, Vladimir

    2013-01-01

    This chapter is focused on antimicrobial modifications of polymer materials intended for medical devices production. Firstly, a brief introduction into the field of medical application of polymers is presented. Considering the fact that polymer medical devices are often connected with occurrence of nosocomial infections, the next part refers to this phenomenon and its causes. One of the possibilities of reducing of the infection occurrence is aimed at polymer modification. It is a key topic o...

  19. A nanoporous two-dimensional polymer by single-crystal-to-single-crystal photopolymerization.

    Science.gov (United States)

    Kissel, Patrick; Murray, Daniel J; Wulftange, William J; Catalano, Vincent J; King, Benjamin T

    2014-09-01

    In contrast to the wide number and variety of available synthetic routes to conventional linear polymers, the synthesis of two-dimensional polymers and unambiguous proof of their structure remains a challenge. Two-dimensional polymers-single-layered polymers that form a tiling network in exactly two dimensions-have potential for use in nanoporous membranes and other applications. Here, we report the preparation of a fluorinated hydrocarbon two-dimensional polymer that can be exfoliated into single sheets, and its characterization by high-resolution single-crystal X-ray diffraction analysis. The procedure involves three steps: preorganization in a lamellar crystal of a rigid monomer bearing three photoreactive arms, photopolymerization of the crystalline monomers by [4 + 4] cycloaddition, and isolation of individual two-dimensional polymer sheets. This polymer is a molecularly thin (~1 nm) material that combines precisely defined monodisperse pores of ~9 Å with a high pore density of 3.3 × 10(13) pores cm(-2). Atomic-resolution single-crystal X-ray structures of the monomer, an intermediate dimer and the final crystalline two-dimensional polymer were obtained and prove the single-crystal-to-single-crystal nature and molecular precision of the two-dimensional photopolymerization.

  20. Thermal diffusivity and mechanical properties of polymer matrix composites

    Science.gov (United States)

    Weidenfeller, Bernd; Anhalt, Mathias; Kirchberg, Stefan

    2012-11-01

    Polypropylene-iron-silicon (FeSi) composites with spherical particles and filler content from 0 vol. % to 70 vol. % are prepared by kneading and injection molding. Modulus, crystallinity, and thermal diffusivity of samples are characterized with dynamic mechanical analyzer, differential scanning calorimeter, and laser flash method. Modulus as well as thermal diffusivity of the composites increase with filler fraction while crystallinity is not significantly affected. Measurement values of thermal diffusivity are close to the lower bound of the theoretical Hashin-Shtrikman model. A model interconnectivity shows a poor conductive network of particles. From measurement values of thermal diffusivity, the mean free path length of phonons in the amorphous and crystalline structure of the polymer and in the FeSi particles is estimated to be 0.155 nm, 0.450 nm, and 0.120 nm, respectively. Additionally, the free mean path length of the temperature conduction connected with the electrons in the FeSi particles together with the mean free path in the particle-polymer interface was estimated. The free mean path is approximately 5.5 nm and decreases to 2.5 nm with increasing filler fraction, which is a result of the increasing area of polymer-particle interfaces. A linear dependence of thermal diffusivity with the square root of the modulus independent on the measurement temperature in the range from 300 K to 415 K was found.