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Sample records for strong liquid-crystalline polymeric

  1. Thermotropic liquid crystalline polyazomethine nanocomposites via in situ interlayer polymerization

    International Nuclear Information System (INIS)

    Min, Ungki; Chang, Jin-Hae

    2011-01-01

    Highlights: → Nanocomposites of polyazomethine with the organoclay C 12 -MMT were synthesized by using the in situ interlayer polymerization method. → The thermal properties of the polyazomethine hybrids increase with the addition of the organoclay up to a critical content and then decrease with further organoclay loading. → Liquid crystalline compositions with 0-9 wt% organoclay have threaded Schlieren nematic textures. - Abstract: Nanocomposites of polyazomethine (PAM) with the organoclay C 12 -MMT were synthesized by using the in situ interlayer polymerization method. The variations with organoclay content of the thermal properties, morphology, and liquid crystalline mesophases of the hybrids were determined for concentrations from 0 to 9 wt% C 12 -MMT. The thermal properties and the morphologies of the PAM nanocomposites were examined by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffractometry (XRD), transmission electron microscopy (TEM), and polarizing optical microscopy (POM). The XRD analysis and TEM micrographs show that the levels of nanosize dispersion can be controlled by varying the C 12 -MMT content. The clay particles are better dispersed in the matrix polymer at low clay contents than at high clay contents. With the exception of the glass transition temperature (T g ), the maximum enhancement in the thermal properties was found to arise at an organoclay content of 1 wt%. Further, the PAM hybrids were shown to exhibit a nematic liquid crystalline phase for organoclay contents in the range 0-9 wt%.

  2. Prediction and design of first super-strong liquid-crystalline polymers

    International Nuclear Information System (INIS)

    Dowell, F.

    1989-01-01

    This paper presents the details of the theoretical prediction and design (atom by atom, bond by bond) of the molecule chemical structures of the first candidate super-strong liquid-crystalline polymers (SS LCPs). These LCPs are the first LCPs designed to have good compressive strengths, as well as to have tensile strengths and tensile moduli significantly larger than those of existing strong LCPs (such as Kevlar). The key feature of this new class of LCPs is that the exceptional strength is three dimensional on a microscopic, molecular level (thus, on a macroscopic level), in contrast to present LCPs (such as Kevlar) with their one-dimensional exceptional strength. These SS LCPs also have some solubility and processing advantages over existing strong LCPs. These SS LCPs are specially-designed combined LCPs such that the side chains of a molecule interdigitate with the side chains of other molecules. This paper also presents other essential general and specific features required for SS LCPs. Considerations in the design of SS LCPs include the spacing distance between side chains along the backbone, the need for rigid sections in the backbone and side chains, the degree of polymerization, the length of the side chains, the regularity of spacing of the side chains along the backbone, the interdigitation of side chains in submolecular strips, the packing of the side chains on one or two sides of the backbone, the symmetry of the side chains, the points of attachment of the side chains to the backbone, the flexibility and size of the chemical group connecting each side chain to the backbone, the effect of semiflexible sections in the backbone and side chains, and the choice of types of dipolar and/or hydrogen bonding forces in the backbones and side chains for easy alignment

  3. Excimer fluorescence of liquid crystalline systems

    Science.gov (United States)

    Sakhno, Tamara V.; Khakhel, Oleg A.; Barashkov, Nikolay N.; Korotkova, Irina V.

    1996-04-01

    The method of synchronous scanning fluorescence spectroscopy shows a presence of dimers of pyrene in a polymeric matrix. The results suggest that excimer formation takes place with dimers in liquid crystalline systems.

  4. 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...... phase behavior and it was possible to convert one such compound partly into its vinylheptafulvene (VHF) isomer upon irradiation with light when in the liquid crystalline phase. This conversion resulted in an increase in the molecular alignment of the phase. In time, the meta-stable VHF returns...... to the DHA where the alignment is maintained. The systematic structural variation has revealed that a biaryl spacer between the DHA and the alkyl chain is needed for liquid crystallinity and that the one aromatic ring in the spacer cannot be substituted by a triazole. This work presents an important step...

  5. 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

  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. Liquid crystalline epoxy nanocomposite material for dental application.

    Science.gov (United States)

    Tai, Yun-Yuan; Hsu, Sheng-Hao; Chen, Rung-Shu; Su, Wei-Fang; Chen, Min-Huey

    2015-01-01

    Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment. Copyright © 2014. Published by Elsevier B.V.

  8. Liquid Crystalline Semiconductors Materials, properties and applications

    CERN Document Server

    Kelly, Stephen; O'Neill, Mary

    2013-01-01

    This is an exciting stage in the development of organic electronics. It is no longer an area of purely academic interest as increasingly real applications are being developed, some of which are beginning to come on-stream. Areas that have already been commercially developed or which are under intensive development include organic light emitting diodes (for flat panel displays and solid state lighting), organic photovoltaic cells, organic thin film transistors (for smart tags and flat panel displays) and sensors. Within the family of organic electronic materials, liquid crystals are relative newcomers. The first electronically conducting liquid crystals were reported in 1988 but already a substantial literature has developed. The advantage of liquid crystalline semiconductors is that they have the easy processability of amorphous and polymeric semiconductors but they usually have higher charge carrier mobilities. Their mobilities do not reach the levels seen in crystalline organics but they circumvent all of t...

  9. 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.

  10. Self-assembly of azobenzene based side-chain liquid crystalline ...

    Indian Academy of Sciences (India)

    The polymeric complexes acquitted as undivided liquid crystalline properties ... India) methanol and other solvents were purified by .... mixture was warmed to room temperature and stirred ... Polymer is soluble in DMF, CHCl3, CH2Cl2 and.

  11. Synthesis, Characterization and Photoinduction of Optical Anisotropy in Liquid Crystalline Diblock Azo-Copolymers

    DEFF Research Database (Denmark)

    Forcén, P; Oriol, L; Sánchez, C

    2007-01-01

    Diblock copolymers with polymethyl methacrylate and side chain liquid crystalline WC) azopolymethacrylate blocks were synthesized by atom transfer radical polymerization (ATRP). The azobeazene content in these copolymers ranges from 52 to 7 wt %. For an azo conteat dowri to 20% they exhibit a LC...... anisotropy induced in these films by illumination with linearly polarized 488 nm light was studied and the resuits compared with those of the azo homopolymer and of a random copolymer with a similar composition. The formation of azo aggregates inside the azo blocks is strongly reduced in going from...... the homopolymer to the copolymers. Photoinduced azo orientation perpendicular to the 488 nm light polarization was found in aH the polymers. The orientational order parameter is very similar in the homopolymer and in the block copolymers with an azo content down to 20 wt %, while it is much lower in the random...

  12. Synthesis, characterization and photoinduction of optical anisotropy in liquid crystalline diblock azo-copolymers

    NARCIS (Netherlands)

    Forcen, P.; Oriol, L.; Sanchez, S.; Alcala, R.; Hvilsted, S.; Jankova, K.; Loos, J.

    2007-01-01

    Diblock copolymers with polymethyl methacrylate and side chain liquid crystalline (LC) azopolymethacrylate blocks were synthesized by atom transfer radical polymerization (ATRP). The azobenzene content in these copolymers ranges from 52 to 7 wt %. For an azo content down to 20% they exhibit a LC

  13. New theories for smectic and nematic liquid crystalline polymers

    International Nuclear Information System (INIS)

    Dowell, F.

    1987-01-01

    A summary of results from new statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with LCPs is presented. Thermodynamic and molecular ordering properties (including odd-even effects) have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories have been used to design new LCPs and new solvents and to predict and explain properties

  14. Langmuir-Blodgett films prepared from pre-formed cholestanic liquid-crystalline polymers

    Energy Technology Data Exchange (ETDEWEB)

    Tundo, P.; Hodge, P.; Valli, L.; Davis, F. (Venice Univ. (Italy). Dip. di Scienze Ambientali Lecce Univ. (Italy). Dip. di Scienza dei Materiali Manchester Univ. (United Kingdom). Dep. of Chemistry)

    1992-01-01

    A series of alternating copolymers of maleic anhydride and a-olefins functionalized through different alkyl chains with cholestanic groups were synthetised and derivatives prepared by reactions of the anhydride residues with methanol, water, dimethylamine and morpholine, respectively. The same starting functionalized a-olefins were used to prepare other suitable compounds in order to correlate the features of the liquid-crystalline behaviour of the mesogenic cholestanic group with the stability of the forthcoming polymeric or not polymeric Langmuir-Blodgett (LB) films. For some copolymers surface pressure against area per molecule isotherms are reported. In some multilayer (LB) films, the spacings between the layers were determined by the detection of BRAGG peaks by X-ray diffraction. The (LB) films of these polymers are closed packed, owing to either the polymeric skeleton or liquid-crystalline interaction.

  15. Liquid crystalline order of carbon nanotubes

    Science.gov (United States)

    Georgiev, Georgi; Ahlawat, Aditya; Mulkern, Brian; Doyle, Robert; Mongeau, Jennifer; Ogilvie, Alex

    2007-03-01

    Topological defects formed during phase transitions in liquid crystals provide a direct proof of the standard Cosmological model and are direct links to the Early Universe. On the other hand in Nanotechnology, carbon nanotubes can be manipulated and oriented directly by changing the liquid crystalline state of the nanotubes, in combination with organic liquid crystals. Currently there are no nano-assemblers, which makes the liquid crystal state of the nanotubes, one of the few ways of controlling them. We show the design of a fast and efficient polarized light ellipsometric system (a new modification of previous optical systems) that can provide fast quantitative real time measurements in two dimensions of the formation of topological defects in liquid crystals during phase transitions in lab settings. Our aim is to provide fundamental information about the formation of optically anisotropic structures in liquid crystals and the orientation of carbon nanotubes in electric field.

  16. Active Mesogenic Droplets: Impact of Liquid Crystallinity and Collective Behavior

    Science.gov (United States)

    Bahr, Christian

    Droplets of common mesogenic compounds show a self-propelled motion when immersed in aqueous solutions containing ionic surfactants at concentrations well above the critical micelle concentration. After introducing some general properties of this type of artificial microswimmer, we focus on two topics: the influence of liquid crystallinity on the swimming behavior and the collective behavior of ensembles of a larger number of droplets. The mesogenic properties are not essential for the basic mechanism of self-propulsion, nevertheless they considerably influence the swimming behavior of the droplets. For instance, the shape of the trajectories strongly depends on whether the droplets are in the nematic or isotropic state. The droplet swimmers are also ideally suited for the study of collective behavior: Microfluidics enables the generation of large numbers of identical swimmers and we can tune their buoyancy. We report on the collective behavior in three-dimensional environments. Supported by the Deutsche Forschungsgemeinschaft (SPP 1726 ``Microswimmers'').

  17. 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.

  18. Effect of Liquid Crystalline Systems Containing Antimicrobial Compounds on Infectious Skin Bacteria.

    Science.gov (United States)

    Souza, Carla; Watanabe, Evandro; Aires, Carolina Patrícia; Lara, Marilisa Guimarães

    2017-08-01

    This study aimed (i) to prepare liquid crystalline systems (LCS) of glyceryl monooleate (GMO) and water containing antibacterial compounds and (ii) to evaluate their potential as drug delivery systems for topical treatment of bacterial infections. Therefore, LCS containing CPC (cetylpyridinium chloride) (LCS/CPC) and PHMB (poly(hexamethylene biguanide) hydrochloride) (LCS/PHMB) were prepared and the liquid crystalline phases were identified by polarizing light microscopy 24 h and 7 days after preparation. The in vitro drug release profile and in vitro antibacterial activity of the systems were assessed using the double layer agar diffusion method against Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, Escherichia coli, and Enterococcus faecalis. The interaction between GMO and the drugs was evaluated by a drug absorption study. Stable liquid crystalline systems containing CPC and PHMB were obtained. LCS/PHMB decreased the PHMB release rate and exerted strong antibacterial activity against all the investigated bacteria. In contrast, CPC interacted with GMO so strongly that it became attached to the system; the amount released was not sufficient to exert antibacterial activity. Therefore, the studied liquid crystalline systems were suitable to deliver PHMB, but not CPC. Accordingly, it was demonstrated that GMO interacts with each drug differently, which may interfere in the final efficiency of GMO/water LCS.

  19. Liquid Crystalline Thermosets from Ester, Ester-imide, and Ester-amide Oligomers

    Science.gov (United States)

    Dingemans, Theodorus J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

    2009-01-01

    Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystaloligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oli-gomers are stable forup to an hour in the melt phase. They are highly processable by a variety of melt process shape forming and blending techniques. Once processed and shaped, the end-capped liquid crystal oigomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures.

  20. Nonlinear optics of liquid crystalline materials

    International Nuclear Information System (INIS)

    Khoo, Iam Choon

    2009-01-01

    Liquid crystals occupy an important niche in nonlinear optics as a result of their unique physical and optical properties. Besides their broadband birefringence and transparency, abilities to self-assemble into various crystalline phases and to conform to various flexible forms and shapes, liquid crystals are compatible with almost all other optoelectronic materials and technology platforms. In both isotropic and ordered phases, liquid crystals possess extraordinarily large optical nonlinearities that stretch over multiple time scales. To date, almost all conceivable nonlinear optical phenomena have been observed in a very broad spectrum spanning the entire visible to infrared and beyond. In this review, we present a self-contained complete discussion of the optical nonlinearities of liquid crystals, and a thorough review of a wide range of nonlinear optical processes and phenomena enabled by these unique properties. Starting with a brief historical account of the development of nonlinear optical studies of the mesophases of liquid crystals, we then review various liquid crystalline materials and structures, and their nonlinear optical properties. Emphasis is placed on the nematic phase, which best exemplifies the dual nature of liquid crystals, although frequent references to other phases are also made. We also delve into recent work on novel structures such as photonic crystals, metamaterials and nanostructures and their special characteristics and emergent properties. The mechanisms and complex nonlocal dynamics of optical nonlinearities associated with laser induced director axis reorientation, thermal, density, and order parameter fluctuations, space charge field formation and photorefractivity are critically reviewed as a foundation for the discussions of various nonlinear optical processes detailed in this paper

  1. Liquid Crystalline Perylene diimides : Architecture and Charge Carrier Mobilities

    NARCIS (Netherlands)

    Struijk, C.W.; Sieval, A.B.; Dakhorst, J.E.J.; Dijk, van M.; Kimkes, P.; Koehorst, R.B.M.; Donker, H.

    2000-01-01

    The phase behavior of three N-alkyl-substituted perylene diimide derivatives is examined by differential scanning calorimetry and polarized optical microscopy. The occurrence of multiple phase transitions indicates several crystalline and several liquid crystalline phases. X-ray diffraction

  2. 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

  3. Bicontinuous cubic liquid crystalline nanoparticles for oral delivery of Doxorubicin

    DEFF Research Database (Denmark)

    Swarnakar, Nitin K; Thanki, Kaushik; Jain, Sanyog

    2014-01-01

    PURPOSE: The present study explores the potential of bicontinous cubic liquid crystalline nanoparticles (LCNPs) for improving therapeutic potential of doxorubicin. METHODS: Phytantriol based Dox-LCNPs were prepared using hydrotrope method, optimized for various formulation components, process...

  4. Liquid crystalline thermosetting polymers as protective coatings for aerospace

    OpenAIRE

    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 unique combination of mechanical properties and chemical resistance. Their use, however, has been limited mainly due to poor adhesion properties. Thermotropic liquid crystalline thermosets displayed ...

  5. Solution processed nanogap organic diodes based on liquid crystalline materials

    Science.gov (United States)

    Wang, Yi-Fei; Iino, Hiroaki; Hanna, Jun-ichi

    2017-09-01

    Co-planar nanogap organic diodes were fabricated with smectic liquid crystalline materials of the benzothienobenzothiophene (BTBT) derivative by a spin-coating technique. A high rectification ratio of the order of 106 at ±3 V was achieved when a liquid crystalline material of 2,7-didecyl benzothieno[3,2-b][1]benzothiophene (10-BTBT-10) was used in a device configuration of Al/10-BTBT-10/pentafluorobenzenethiol-treated Au on a glass substrate, which was 4 orders higher than that of the device based on non-liquid crystalline materials of 2,7-dibutyl benzothieno[3,2-b][1]benzothiophene (4-BTBT-4) and BTBT. Similar results were also observed when another liquid crystalline material of ω, ω'-dioctylterthiophene (8-TTP-8) and a non-liquid crystalline material of terthiophene (TTP) were used. These improved rectifications can be ascribed to the self-assembly properties and controllable molecular orientation of liquid crystalline materials, which made uniform perpendicular oriented polycrystalline films favorable for superior charge transport in nano-channels.

  6. Computer simulation of confined and flexoelectric liquid crystalline systems

    International Nuclear Information System (INIS)

    Barmes, F.

    2003-01-01

    In this Thesis, systems of confined and flexoelectric liquid crystal systems have been studied using molecular computer simulations. The aim of this work was to provide a molecular model of a bistable display cell in which switching is induced through the application of directional electric field pulses. In the first part of this Thesis, the study of confined systems of liquid crystalline particles has been addressed. Computation of the anchoring phase diagrams for three different surface interaction models showed that the hard needle wall and rod-surface potentials induce both planar and homeotropic alignment separated by a bistability region, this being stronger and wider for the rod-surface varant. The results obtained using the rod-sphere surface model, in contrast, showed that tilled surface arrangements can be induced by surface absorption mechanisms. Equivalent studies of hybrid anchored systems showed that a bend director structure can be obtained in a slab with monostable homeotropic anchoring at the top surface and bistable anchoring at the bottom, provided that the slab height is sufficiently large and the top homeotropic anchoring is not too strong. In the second part of the Thesis, the development of models for tapered (pear-shaped) mesogens has been addressed. The first model considered, the truncated Stone expansion model, proved to be unsuccessful in that it did not display liquid crystalline phases. This drawback was then overcome using the alternative parametric hard Gaussian overlap model which was found to display a much richer phase behaviour. With a molecular elongation k = 5, both nematic and interdigitated smectic A 2 phases were obtained. In the final part of this Thesis, the knowledge acquired from the two previous studies was united in an attempt to model a bistable display cell. Switching between the hybrid aligned nematic and vertical states of the cell was successfully performed using pear shaped particles with both dielectric and

  7. 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.

  8. White emission from liquid-crystalline copolymers containing oxadiazole moieties in the side chain

    Science.gov (United States)

    Kawamoto, Masuki; Tsukamoto, Takuji; Kinoshita, Motoi; Ikeda, Tomiki

    2006-09-01

    A liquid-crystalline polymer in the side chain was synthesized through copolymerization of a bipolar carrier-transporting monomer with a liquid-crystalline monomer containing oxadiazole moieties substituted with trifluoromethyl groups. A single-layer light-emitting diode of indium tin oxide (ITO)/copolymer/MgAg emitted white light with a maximum luminous efficiency of 0.1cd/A. The origin of the white emission in the copolymer is the electroplex between bipolar carrier-transporting moieties and strong electron-withdrawing moieties. Furthermore, a simple multilayer device with configuration of ITO/poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid)/copolymer/MgAg device showed white emission with CIE 1931 chromaticity coordinates (x,y): (0.30, 0.33).

  9. Liquid-Crystalline Ionic Liquids as Ordered Reaction Media for the Diels-Alder Reaction.

    Science.gov (United States)

    Bruce, Duncan W; Gao, Yanan; Canongia Lopes, José Nuno; Shimizu, Karina; Slattery, John M

    2016-11-02

    Liquid-crystalline ionic liquids (LCILs) are ordered materials that have untapped potential to be used as reaction media for synthetic chemistry. This paper investigates the potential for the ordered structures of LCILs to influence the stereochemical outcome of the Diels-Alder reaction between cyclopentadiene and methyl acrylate. The ratio of endo- to exo-product from this reaction was monitored for a range of ionic liquids (ILs) and LCILs. Comparison of the endo:exo ratios in these reactions as a function of cation, anion and liquid crystallinity of the reaction media, allowed for the effects of liquid crystallinity to be distinguished from anion effects or cation alkyl chain length effects. These data strongly suggest that the proportion of exo-product increases as the reaction media is changed from an isotropic IL to a LCIL. A detailed molecular dynamics (MD) study suggests that this effect is related to different hydrogen bonding interactions between the reaction media and the exo- and endo-transition states in solvents with layered, smectic ordering compared to those that are isotropic. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Induction of Liquid Crystallinity by Self-Assembled Molecular Boxes

    NARCIS (Netherlands)

    Piermattei, A.; Giesbers, M.; Marcelis, A.T.M.; Mendes, E.; Picken, S.J.; Crego-Calama, M.; Reinhoudt, D.N.

    2006-01-01

    In a hierarchical process, three molecules of a calix[4]arene (blue) and six of barbituric or cyanuric acid (green) assemble into double-rosette boxes, which assemble into columns, which in turn assemble into columnar liquid-crystalline phases (see picture). The resulting mesophases have a

  11. Rotational reorganization of doped cholesteric liquid crystalline films

    NARCIS (Netherlands)

    Eelkema, R.; M. Pollard, M.; Katsonis, N.; Vicario, J.; J. Broer, D.; Feringa, B.L.

    2006-01-01

    In this paper an unprecedented rotational reorganization of cholesteric liquid crystalline films is described. This rotational reorganization results from the conversion of a chiral molecular motor dopant to an isomer with a different helical twisting power, leading to a change in the cholesteric

  12. Thermotropic liquid crystalline polyesters derived from 2-chloro ...

    Indian Academy of Sciences (India)

    NAGESH MANURKAR

    2017-08-24

    Aug 24, 2017 ... extremely useful for various applications including fab- rication of numerous ... In another flask, sodium hydroxide (4.4 g, 0.11 mole) was dissolved in 50 ..... relationships of smectic liquid crystalline polyacrylates as revealed by ...

  13. Investigations on the liquid crystalline phases of cation-induced ...

    Indian Academy of Sciences (India)

    liquid crystalline phases of Li–DNA system could be useful in the production of ... undergo unidirectional ordering (the solution starts to become birefringent under ... was spread over the glass slides with a cover slip and sealed with a neutral ...

  14. Reactions and Interactions in Liquid Crystalline Media

    Science.gov (United States)

    1991-10-30

    nematic lyophases of potassium laurate, myristyl tri methylammonium bromide or sodium decylsulfate with 1-decanol and 23 water. A strong retardation of the...crystalline polyacrylate crosslinked elastomers were synthesized. 198c 0 0 96 0 0 0O-(CH12 ) 2 -0O(k 97 Crosslinking, up to 10% of structural units produced...in their isotropic state and they work as the transporting phase for the azo-crown ether molecules. The permeation of K+ from a potassium p

  15. Controlling the morphology of side chain liquid crystalline block copolymer thin films through variations in liquid crystalline content.

    Science.gov (United States)

    Verploegen, Eric; Zhang, Tejia; Jung, Yeon Sik; Ross, Caroline; Hammond, Paula T

    2008-10-01

    In this paper, we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase-segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the anchoring of the LC mesophase relative to the substrate and the intermaterial dividing surface. By manipulating the strength of these interactions, the arrangement and ordering of the ultrathin film block copolymer nanostructures can be controlled, yielding a range of morphologies that includes perpendicular and parallel cylinders, as well as both perpendicular and parallel lamellae. Additionally, we demonstrate the utilization of selective etching to create a nanoporous liquid crystalline polymer thin film. The unique control over the orientation and order of the self-assembled morphologies with respect to the substrate will allow for the custom design of thin films for specific nanopatterning applications without manipulation of the surface chemistry or the application of external fields.

  16. 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.

  17. Liquid crystalline fiber optic colorimeter for hydrostatic pressure measurement

    Science.gov (United States)

    Wolinski, Tomasz R.; Bajdecki, Waldemar K.; Domanski, Andrzej W.; Karpierz, Miroslaw A.; Konopka, Witold; Nasilowski, T.; Sierakowski, Marek W.; Swillo, Marcin; Dabrowski, Roman S.; Nowinowski-Kruszelnicki, Edward; Wasowski, Janusz

    2001-08-01

    This paper presents results of tests performed on a fiber optic system of liquid crystalline transducer for hydrostatic pressure monitoring based on properties of colorimetry. The system employs pressure-induced deformations occurring in liquid crystalline (LC) cells configured in a homogeneous Frederiks geometry. The sensor is compared of a round LC cell placed inside a specially designed pressure chamber. As a light source we used a typical diode operating at red wavelength and modulated using standard techniques. The pressure transducer was connected to a computer with a specially designed interface built on the bas of advanced ADAM modules. Results indicate that the system offers high response to pressure with reduced temperature sensitivity and, depending on the LC cell used, can be adjusted for monitoring of low hydrostatic pressures up to 6 MPa. These studies have demonstrated the feasibility of fiber optic liquid crystal colorimeter for hydrostatic pressure sensing specially dedicated to pipe- lines, mining instrumentation, and process-control technologies.

  18. Liquid crystalline epoxy nanocomposite material for dental application

    Directory of Open Access Journals (Sweden)

    Yun-Yuan Tai

    2015-01-01

    Conclusion: The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment.

  19. Side-chain liquid crystalline polyesters for optical information storage

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Holme, Christian; Hvilsted, Søren

    1996-01-01

    and holographic storage in one particular polyester are described in detail and polarized Fourier transform infrared spectroscopic data complementing the optical data are presented. Optical and atomic force microscope investigations point to a laser-induced aggregation as responsible for permanent optical storage.......Azobenzene side-chain liquid crystalline polyester structures suitable for permanent optical storage are described. The synthesis and characterization of the polyesters together with differential scanning calorimetry and X-ray investigations are discussed. Optical anisotropic investigations...

  20. Liquid crystalline tactoids: ordered structure, defective coalescence and evolution in confined geometries

    Science.gov (United States)

    Wang, Pei-Xi; MacLachlan, Mark J.

    2017-12-01

    Tactoids are liquid crystalline microdroplets that spontaneously nucleate from isotropic dispersions, and transform into macroscopic anisotropic phases. These intermediate structures have been found in a range of molecular, polymeric and colloidal liquid crystals. Typically only studied by polarized optical microscopy, these ordered but easily deformable microdroplets are now emerging as interesting components for structural investigations and developing new materials. In this review, we highlight the structure, property and transformation of tactoids in different compositions, but especially cellulose nanocrystals. We have selected references that illustrate the diversity and most exciting developments in tactoid research, while capturing the historical development of this field. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

  1. Thermoresponsive Membrane Based on Thermotropic Liquid Crystalline Cholesteryl - (L-lacticacidn System: Study of Its Drug Permeability

    Directory of Open Access Journals (Sweden)

    Massoumeh Bagheri

    2013-01-01

    Full Text Available The rapidly increasing interest in functional materials with reversibly switchable physico- chemical properties has led to significant work on the development of stimuli responsive membranes. Thermotropic liquid crystals with their exceptional properties have potentials for drug-delivery applications. Thermoresponsive liquid-crystal-embedded membranes were investigated for the purpose of developing the drug delivery systems with thermal stimuli response. Drug release occurs at temperatures above the phase transition temperature of thermotropic liquid crystals. Therefore, they can control drug release in response to small temperature changes. In this work, the biocompatible and thermotropic liquid crystalline polymer cholesteryl-(L-lactic acidn ,CLAn (n=30, was synthesized with accurate control of molecular weight via ring opening polymerization method. Polymerization of L-lactide was carried out in the presence of cholesterol as an initiator and catalytic amount of tin (II octoate (Sn(Oct2 at 150°C in 5 h. The number-average degree of polymerization of CLA 30 was obtained from 1H NMR spectroscopy. The phase transition behavior of liquid crystalline CLA30 was established by differential scanning calorimetry and polarizing optical microscopy. The resulting liquid crystalline CLA30 was subsequently utilized to prepare CLA30 -embedded cellulose nitrate membrane by adsorption method. The CLA30-embedded cellulose nitrate membrane was used by an in-vitro drug penetration studies. Acetaminophen was used as a model drug. The permeation study was carried out at different temperatures around glass transition temperature of polymer CLA30 (37, 45 and 40°C, respectively. The results show that the CLA30 -embedded cellulose nitrate membranes exhibit thermo-responsive sensitivity with controlled drug permeation.

  2. Liquid crystalline biopolymers: A new arena for liquid crystal research

    International Nuclear Information System (INIS)

    Rizvi, Tasneem Zahra

    2001-07-01

    This paper gives a brief introduction to liquid crystals on the basis of biopolymers and reviews literature on liquid crystalline behaviour of biopolymers both in vitro and in vivo in relation to their implications in the fields of biology, medicine and material science. Knowledge in the field of biological liquid crystals is crucial for understanding complex phenomena at supramolecular level which will give information about processes involved in biological organization and function. The understanding of the interaction of theses crystals with electric, magnetic, optical and thermal fields will uncover mechanisms of near quantum-energy detection capabilities of biosystems

  3. Structural studies of different types of ferroelectric liquid crystalline substances

    Czech Academy of Sciences Publication Activity Database

    Obadović, D.Ž.; Stojanović, M.; Bubnov, Alexej; Éber, N.; Cvetinov, M.; Vajda, A.

    2011-01-01

    Roč. 35, č. 1 (2011), s. 3-13 ISSN 1450-7404 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA ČR(CZ) GAP204/11/0723 Grant - others:RFASI(RU) 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystals * phase transition * structure of liquid crystalline phases * molecular parameters Subject RIV: BM - Solid Matter Physics ; Magnetism

  4. Intestinal mucus and juice glycoproteins have a liquid crystalline structure

    International Nuclear Information System (INIS)

    Denisova, E.A.; Lazarev, P.I.; Vazina, A.A.; Zheleznaya, L.A.

    1985-01-01

    X-ray diffraction patterns have been obtained from the following components of canine gastrointestinal tract: (1) native small intestine mucus layer; (2) the precipitate of the flocks formed in the duodenal juice with decreasing pH; (3) concentrated solutions of glycoproteins isolated from the duodenal juice. The X-ray patterns consist of a large number of sharp reflections of spacings between about 100 and 4 A. Some reflections are common for all components studied. All the patterns are interpreted as arising from the glycoprotein molecules ordered into a liquid crystalline structure. (author)

  5. Thermal degradation of polymer systems having liquid crystalline oligoester segment

    Directory of Open Access Journals (Sweden)

    Renato Matroniani

    Full Text Available Abstract Block copolymers and blends comprised by liquid crystalline oligoester and polystyrene were prepared and their thermal stability were characterized by thermogravimetric analysis (TGA. The samples have shown three main decomposition temperatures due to (1 lost of flexible chain and decomposition of mesogenic segment, (2 decomposition of polystyrene and (3 final decomposition of oligoester rigid segment. Both copolymers and polymer blends presented lower thermal stability compared to polystyrene and oligoester. The residual mass after heating at 600 °C in copolymers and polymer blends were lower than those found in the oligoesters. A degradative process of aromatic segments of oligoester induced by decomposition of polystyrene is suggested.

  6. Electric properties of a liquid crystalline methacrylic polymer

    International Nuclear Information System (INIS)

    Gonzalez Henriquez, C.M.; Soto Bustamante, E.A.; Haase, W.

    2009-01-01

    The formation of a liquid crystalline polymer called PM6R8 is reported. The polymers were obtained with different concentration of AIBN as initiator (0.25, 0.50, 1 and 2mg in 5ml solution) and time of reaction (24, 36 and 48 hours). The compounds were characterized by 1 H-NMR, differential thermal analysis (DTA), X-ray diffractometer and pyroelectric measurements. For the polymer a smectic C 2 phase occurs over broad temperature range, which is a possible explanation for the electric signal. The arrangement of the molecules within of the crystalline lattice is related with the kinetic of precipitation. (author)

  7. 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.

  8. Dry Powder Precursors of Cubic Liquid Crystalline Nanoparticles (cubosomes)

    International Nuclear Information System (INIS)

    Spicer, Patrick T.; Small, William B.; Small, William B.; Lynch, Matthew L.; Burns, Janet L.

    2002-01-01

    Cubosomes are dispersed nanostructured particles of cubic phase liquid crystal that have stimulated significant research interest because of their potential for application in controlled-release and drug delivery. Despite the interest, cubosomes can be difficult to fabricate and stabilize with current methods. Most of the current work is limited to liquid phase processes involving high shear dispersion of bulk cubic liquid crystalline material into sub-micron particles, limiting application flexibility. In this work, two types of dry powder cubosome precursors are produced by spray-drying: (1) starch-encapsulated monoolein is produced by spray-drying a dispersion of cubic liquid crystalline particles in an aqueous starch solution and (2) dextran-encapsulated monoolein is produced by spray-drying an emulsion formed by the ethanol-dextran-monoolein-water system. The encapsulants are used to decrease powder cohesion during drying and to act as a soluble colloidal stabilizer upon hydration of the powders. Both powders are shown to form (on average) 0.6 μm colloidally-stable cubosomes upon addition to water. However, the starch powders have a broader particle size distribution than the dextran powders because of the relative ease of spraying emulsions versus dispersions. The developed processes enable the production of nanostructured cubosomes by end-users rather than just specialized researchers and allow tailoring of the surface state of the cubosomes for broader application

  9. Volume phase transitions of cholesteric liquid crystalline gels.

    Science.gov (United States)

    Matsuyama, Akihiko

    2015-05-07

    We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.

  10. Volume phase transitions of cholesteric liquid crystalline gels

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Akihiko, E-mail: matuyama@bio.kyutech.ac.jp [Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502 (Japan)

    2015-05-07

    We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.

  11. Quantitative Analysis of Matrine in Liquid Crystalline Nanoparticles by HPLC

    Directory of Open Access Journals (Sweden)

    Xinsheng Peng

    2014-01-01

    Full Text Available A reversed-phase high-performance liquid chromatographic method has been developed to quantitatively determine matrine in liquid crystal nanoparticles. The chromatographic method is carried out using an isocratic system. The mobile phase was composed of methanol-PBS(pH6.8-triethylamine (50 : 50 : 0.1% with a flow rate of 1 mL/min with SPD-20A UV/vis detector and the detection wavelength was at 220 nm. The linearity of matrine is in the range of 1.6 to 200.0 μg/mL. The regression equation is y=10706x-2959 (R2=1.0. The average recovery is 101.7%; RSD=2.22%  (n=9. This method provides a simple and accurate strategy to determine matrine in liquid crystalline nanoparticle.

  12. Liquid crystallinity in flexible and rigid rod polymers

    International Nuclear Information System (INIS)

    Pickett, Galen T.; Schweizer, Kenneth S.

    2000-01-01

    We apply an anisotropic version of the polymer reference interaction site model (PRISM) integral equation description of flexible polymers to analyze athermal liquid crystallinity. The polymers are characterized by a statistical segment length, σ o , and by a physical hard-core thickness, d, that prevents the overlap of monomers on different chains. At small segment densities, ρ, the microscopic length scale d is irrelevant (as it must be in the universal semidilute regime), but becomes important in concentrated solutions and melts. Under the influence of the excluded volume interactions alone, the chains undergo a lyotropic, first-order isotropic-nematic transition at a concentration dependent upon the dimensionless ''aspect ratio,'' σ o /d. The transition becomes weaker as d→0, becoming second order, as has been previously shown. We extend the theory to describe the transition of rigid, thin rods, and discuss the evolution of the anisotropic liquid structure in the ordered phase. (c) 2000 American Institute of Physics

  13. The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

    Directory of Open Access Journals (Sweden)

    Joscha Vollmeyer

    2014-04-01

    Full Text Available A series of shape-persistent phenylene–ethynylene–naphthylene–butadiynylene macrocycles with different extraannular alkyl groups and intraannular bridges is synthesized by oxidative Glaser-coupling of the appropriate precursors. The intraannular bridges serve in this case as templates that reduce the oligomerization even when the reaction is not performed under pseudo high-dilution conditions. The extraannular as well as the intraannular substituents have a strong influence on the thermal behavior of the compounds. With branched alkyl chains at the periphery, the macrocycles exhibit liquid crystalline (lc phases when the interior is empty or when the length of the alkyl bridge is just right to cross the ring. With a longer alkyl or an oligoethylene oxide bridge no lc phase is observed, most probably because the mesogene is no longer planar.

  14. Autophobicity and layering behavior of thin liquid-crystalline polymer films.

    NARCIS (Netherlands)

    Wielen, van der M.W.J.; Cohen Stuart, M.A.; Fleer, G.J.

    1998-01-01

    The stability against breaking-up of thin spin-coated films of liquid-crystalline polymers depends on the film thickness and annealing temperature. This study concerns side-chain liquid-crystalline polymers, based on alternating copolymers of maleic anhydride and mesogenic alkenes. The mesogenic

  15. Phosphoric acids as amplifiers of molecular chirality in liquid crystalline media

    NARCIS (Netherlands)

    Eelkema, R; Feringa, BL

    2006-01-01

    A new system for the double amplification of the molecular chirality of simple chiral amines in achiral liquid crystalline media is described. It involves a conformationally flexible phosphoric acid based receptor that by binding to chiral amines induces chirality in the liquid crystalline matrix.

  16. 21 CFR 524.2620 - Liquid crystalline trypsin, Peru balsam, castor oil.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Liquid crystalline trypsin, Peru balsam, castor... NEW ANIMAL DRUGS § 524.2620 Liquid crystalline trypsin, Peru balsam, castor oil. (a)(1) Specifications... delivered to the wound site contains 0.12 milligram of crystalline trypsin, 87.0 milligrams of Peru balsam...

  17. Liquid crystalline solutions of cellulose in phosphoric acid for preparing cellulose yarns

    NARCIS (Netherlands)

    Boerstoel, H.

    2006-01-01

    The presen thesis describes a new process for manufacturing high tenacity and high modulus cellulose yarns. A new direct solvent for cellulose has been discovered, leading to liquid crystalline solutions. This new solvent, superphosphoric acid, rapidly dissolves cellulose. These liquid crystalline

  18. Drug Release and Skin Permeation from Lipid Liquid Crystalline Phases

    Science.gov (United States)

    Costa-Balogh, F. O.; Sparr, E.; Sousa, J. J. S.; Pais, A. A. C. C.

    We have studied drug release and skin permeation from several different liquid crystalline lipid formulations that may be used to control the respective release rates. We have studied the release and permeation through human skin of a water-soluble and amphiphilic drug, propranolol hydrochloride, from several formulations prepared with monoolein and phytantriol as permeation enhancers and controlled release excipients. Diolein and cineol were added to selected formulations. We observed that viscosity decreases with drug load, wich is compatible with the occurrence of phase changes. Diolein stabilizes the bicontinuous cubic phases leading to an increase in viscosity and sustained release of the drug. The slowest release was found for the cubic phases with higher viscosity. Studies on skin permeation showed that these latter formulations also presented lower permeability than the less viscous monoolein lamellar phases. Formulations containing cineol originated higher permeability with higher enhancement ratios. Thus, the various formulations are adapted to different circumstances and delivery routes. While a slow release is usually desired for drug sustained delivery, the transdermal route may require a faster release. Lamellar phases, which are less viscous, are more adapted to transdermal applications. Thus, systems involving lamellar phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol hydrochloride.

  19. Liquid crystalline composites toward organic photovoltaic application (Conference Presentation)

    Science.gov (United States)

    Shimizu, Yo; Sosa-Vargas, Lydia; Shin, Woong; Higuchi, Yumi; Itani, Hiromichi; Kawano, Koki; Dao, Quang Duy; Fujii, Akihiko; Ozaki, Masanori

    2017-02-01

    Liquid crystalline semiconductor is an interesting category of organic electronic materials and also has been extensively studied in terms of "Printed Electronics". For the wider diversity in research toward new applications, one can consider how to use a combination of miscibility and phase separation in liquid crystals. Here we report discotic liquid crystals in making a composite of which structural order is controlled in nano-scale toward photovoltaic applications. Discotic columnar LCs were studied on their resultant molecular order and carrier transport properties. Liquid crystals of phthalocyanine and its analogues which exhibit columnar mesomorphism with high carrier mobility (10-1 cm2/Vs) were examined with making binary phase diagrams and the correlation to carrier transport properties by TOF measurements was discussed. The shape-analogues in chemical structure shows a good miscibility even for the different lattice-type of columnar arrangement and the carrier mobility is mostly decrease except for a case of combination with a metal-free and the metal complex. For the mixtures with non-mesogenic C60 derivatives, one sees a phase-separated structure due to its immiscibility, though the columnar order is remained in a range of component ratio.Especially, in a range of the ratio, it was observed the phase separated C60 derivatives are fused into the matrix of columnar bundles, indicating C60 derivatives could be diffused in columnar arrays in molecular level.

  20. Functionalized Nanoporous Polymer Membranes with Well-Defined Pore Architectures via Lyotropic Liquid-Crystalline Monomers

    National Research Council Canada - National Science Library

    Gin, Douglas

    1997-01-01

    .... Two lyotropic liquid-crystalline monomer platforms have been synthesized. The interchannel separations in the polymerizable materials can be varied in the 30-40 A range by the choice of counterion on the ionic headgroup of the monomers...

  1. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 4 - Synthesis of side-chain liquid crystalline polycarbonates with mesogenic groups having tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    Side-chain liquid crystalline polycarbonates with alkoxyphenylbenzoate side groups, having a short spacer and tails ranging from 1 to 8 C-atoms, were synthesized. The polymers were prepared by an organo-zinc catalysed copolymerization of carbon dioxide and mesogenic 4-alkoxyphenyl

  2. Droplet snap-off in fluids with nematic liquid crystalline ordering

    International Nuclear Information System (INIS)

    Verhoeff, A A; Lekkerkerker, H N W

    2012-01-01

    We studied the snap-off of nematic liquid crystalline droplets originating from the Rayleigh-Taylor instability at the isotropic-nematic interface in suspensions of charged gibbsite in water and sterically stabilized gibbsite in bromotoluene. We found that droplet snap-off strongly depends on the director field structure inside the thinning neck, which is determined by the ratio of the splay elastic constant and the anchoring strength of the nematic phase to the droplet interface relative to the thickness of the thinning neck. If anchoring is weak, which is the case for aqueous gibbsite, this ratio is comparable to the thickness of the breaking thread. As a result, the thinning neck and pending drop have a uniform director field and droplet snap-off is determined by the viscous properties of the liquid crystal as well as by thermal fluctuations of the interface. On the other hand, in sterically stabilized gibbsite where anchoring is strong, this ratio is significantly smaller than the neck thickness. In this case, the neck has an escaped radial director field and the neck thinning is retarded close to snap-off due to a topological energy barrier involved in the separation of the droplet from the thread. (paper)

  3. 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.

  4. Competitive concurrence of surface wrinkling and dewetting of liquid crystalline polymer films on non-wettable substrates.

    Science.gov (United States)

    Song, Sung E; Choi, Gwan H; Yi, Gi-Ra; Yoo, Pil J

    2017-11-01

    Polymeric thin films coated on non-wettable substrates undergo film-instabilities, which are usually manifested as surface deformation in the form of dewetting or wrinkling. The former takes place in fluidic films, whereas the latter occurs in solid films. Therefore, there have rarely been reports of systems involving simultaneous deformations of dewetting and wrinkling. In this study, we propose polymeric thin films of liquid crystalline (LC) mesogens prepared on a non-wettable Si substrate and apply a treatment of plasma irradiation to form a thin polymerized layer at the surface. The resulting compressive stress generated in the surface region drives the formation of wrinkles, while at the same time, dipolar attraction between LC molecules induces competitive cohesive dewetting. Intriguing surface structures were obtained whereby dewetting-like hole arrays are nested inside the randomly propagated wrinkles. The structural features are readily controlled by the degree of surface cross-linking, hydrophilicity of the substrates, and the LC film thickness. In particular, dewetting of LC mesogens is observed to be restricted to occur at the trough regions of wrinkles, exhibiting the typical behavior of geometrically confined dewetting. Finally, wrinkling-dewetting mixed structures are separated from the substrate in the form of free standing films to demonstrate the potential applicability as membranes.

  5. Phase behaviour of macromolecular liquid crystalline materials. Computational studies at the molecular level

    International Nuclear Information System (INIS)

    Stimson, Lorna 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 single dendrimer molecule in the gas phase at the atomistic level, semi-atomistic molecular dynamics of a single molecule in liquid crystalline solvents and a coarse-grained molecular dynamics study of the dendrimer in the bulk. The coarse-grained model has been developed and parameterized using the results of the atomistic and semi-atomistic work. The single molecule studies showed that the liquid crystalline dendrimer was able to change its structure by conformational changes in the flexible chains that link the mesogenic groups to the core. Structural change was seen under the application of a mean field ordering potential in the gas phase, and in the presence of liquid crystalline solvents. No liquid crystalline phases were observed for the bulk phase studies of the coarse-grained model. However, when the length of the mesogenic units was increased there was some evidence for microphase separation in these systems. (author)

  6. 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

  7. Induction of liquid crystallinity of by self-assembled molecular boxes

    NARCIS (Netherlands)

    Piermattei, A.; Giesbers, Marcel; Marcelis, Antonius T.M.; Mendes, Eduardo; Picken, Stephen J.; Crego Calama, Mercedes; Reinhoudt, David

    2006-01-01

    Jewel-box: In a hierarchical process, three molecules of a calix[4]arene (blue) and six of barbituric or cyanuric acid (green) assemble into double-rosette boxes, which assemble into columns, which in turn assemble into columnar liquid-crystalline phases (see picture). The resulting mesophases have

  8. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    DEFF Research Database (Denmark)

    Sánchez, C; Alcalá, R; Hvilsted, Søren

    2001-01-01

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution...

  9. Novel biphotonic holographic storage in a side-chain liquid crystalline polyester

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Hvilsted, S.; Andruzzi, F.

    1993-01-01

    We report novel biphotonic holographic storage of text and gratings on unoriented films of a side-chain liquid crystalline polyester capable of high density storage and complete erasure. The holograms have a typical size of 1 mm. The recording utilizes unusual photochemistry involving azo dye...

  10. Light-induced circular birefringence in cyanoazobenzene side-chain liquid-crystalline polyester films

    DEFF Research Database (Denmark)

    Naydenova, I; Nikolova, L; Ramanujam, P.S.

    1999-01-01

    We report the inducement of large circular birefringence (optical activity) in films of a cyanoazobenzene side-chain liquid-crystalline polyester on illumination with circularly polarized light. The polyester has no chiral groups and is initially isotropic. The induced optical rotation is up to 5...

  11. Dicyanamide Salts that Adopt Smectic, Columnar, or Bicontinuous Cubic Liquid-Crystalline Mesophases.

    Science.gov (United States)

    Park, Geonhui; Goossens, Karel; Shin, Tae Joo; Bielawski, Christopher W

    2018-04-25

    Although dicyanamide (i.e., [N(CN) 2 ] - ) has been commonly used to obtain low-viscosity, halogen-free, room-temperature ionic liquids, liquid-crystalline salts containing such anions have remained virtually unexplored. Here we report a series of amphiphilic dicyanamide salts that, depending on their structures and compositions, adopt smectic, columnar, or bicontinuous cubic thermotropic liquid-crystalline mesophases, even at room temperature in some cases. Their thermal properties were explored by polarized light optical microscopy, differential scanning calorimetry, thermogravimetric analysis (including evolved gas analysis), and variable-temperature synchrotron X-ray diffraction. Comparison of the thermal phase characteristics of these new liquid-crystalline salts featuring "V-shaped" [N(CN) 2 ] - anions with those of structural analogues containing [SCN] - , [BF 4 ] - , [PF 6 ] - , or [CF 3 SO 3 ] - anions indicated that not only the size of the counterion but also its shape should be considered in the development of mesomorphic salts. Collectively, these discoveries may be expected to facilitate the design of thermotropic ionic liquid crystals that form inverted-type bicontinuous cubic and other sophisticated liquid-crystalline phases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

    Science.gov (United States)

    Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie

    2009-01-01

    Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

  13. The microwave heating mechanism of N-(4-methoxybenzyliden)-4-butylaniline in liquid crystalline and isotropic phases as determined using in situ microwave irradiation NMR spectroscopy.

    Science.gov (United States)

    Tasei, Yugo; Tanigawa, Fumikazu; Kawamura, Izuru; Fujito, Teruaki; Sato, Motoyasu; Naito, Akira

    2015-04-14

    Microwave heating effects are widely used in the acceleration of organic, polymerization and enzymatic reactions. These effects are primarily caused by the local heating induced by microwave irradiation. However, the detailed molecular mechanisms associated with microwave heating effects on the chemical reactions are not yet well understood. This study investigated the microwave heating effect of N-(4-methoxybenzylidene)-4-butylaniline (MBBA) in liquid crystalline and isotropic phases using in situ microwave irradiation nuclear magnetic resonance (NMR) spectroscopy, by obtaining (1)H NMR spectra of MBBA under microwave irradiation. When heated simply using the temperature control unit of the NMR instrument, the liquid crystalline MBBA was converted to the isotropic phase exactly at its phase transition temperature (Tc) of 41 °C. The application of microwave irradiation at 130 W for 90 s while maintaining the instrument temperature at 20 °C generated a small amount of isotropic phase within the bulk liquid crystal. The sample temperature of the liquid crystalline state obtained during microwave irradiation was estimated to be 35 °C by assessing the linewidths of the (1)H NMR spectrum. This partial transition to the isotropic phase can be attributed to a non-equilibrium local heating state induced by the microwave irradiation. The application of microwave at 195 W for 5 min to isotropic MBBA while maintaining an instrument temperature of 50 °C raised the sample temperature to 160 °C. In this study, the MBBA temperature during microwave irradiation was estimated by measuring the temperature dependent chemical shifts of individual protons in the sample, and the different protons were found to indicate significantly different temperatures in the molecule. These results suggest that microwave heating polarizes bonds in polar functional groups, and this effect may partly explain the attendant acceleration of organic reactions.

  14. Liquid crystalline states of surfactant solutions of isotropic micelles

    International Nuclear Information System (INIS)

    Bagdassarian, C.; Gelbart, W.M.; Ben-Shaul, A.

    1988-01-01

    We consider micellar solutions whose surfactant molecules prefer strongly to form small, globular aggregates in the absence of intermicellar interactions. At sufficiently high volume fraction of surfactant, the isotropic phase of essentially spherical micelles is shown to be unstable with respect to an orientationally ordered (nematic) state of rodlike aggregates. This behavior is relevant to the phase diagrams reported for important classes of aqueous amphiphilic solutions

  15. Investigating the dominant corrections to the strong-stretching theory for dry polymeric brushes.

    Science.gov (United States)

    Matsen, M W

    2004-07-22

    The accuracy of strong-stretching theory (SST) is examined against a detailed comparison to self-consistent field theory (SCFT) on dry polymeric brushes with thicknesses of up to approximately 17 times the natural chain extension. The comparison provides the strongest evidence to date that SST represents the exact thick-brush limit of SCFT. More importantly, it allows us to assess the effectiveness of proposed finite-stretching corrections to SST. Including the entropy of the free ends is shown to rectify the most severe inaccuracies in SST. The proximal layer proposed by Likhtman and Semenov provides another significant improvement, and we identify one further effect of similar importance for which there is not yet an accurate treatment. Furthermore, our study provides a valuable means of rejecting mistaken refinements to SST, and indeed one such example is revealed. A proper treatment of finite-stretching corrections is vital to a wide range of phenomena that depend on a small excess free energy, such as autophobic dewetting and the interaction between opposing brushes.

  16. 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.

  17. 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.

  18. Photo-responsive liquid crystalline epoxy networks with exchangeable disulfide bonds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuzhan [Washington State Univ., Pullman, WA (United States); Zhang, Yuehong [Washington State Univ., Pullman, WA (United States); Rios, Orlando [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Keum, Jong K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kessler, Michael R. [Washington State Univ., Pullman, WA (United States); North Dakota State Univ., Fargo, ND (United States)

    2017-07-27

    The increasing demand for intelligent materials has driven the development of polymers with a variety of functionalities. However, combining multiple functionalities within one polymer is still challenging because of the difficulties encountered in coordinating different functional building blocks during fabrication. In this work, we demonstrate the fabrication of a multifunctional liquid crystalline epoxy network (LCEN) using the combination of thermotropic liquid crystals, photo-responsive azobenzene molecules, and exchangeable disulfide bonds. In addition to shape memory behavior enabled by the reversible liquid crystalline phase transition and photo-induced bending behavior resulting from the photo-responsive azobenzene molecules, the introduction of dynamic disulfide bonds into the LCEN resulted in a structurally dynamic network, allowing the reshaping, repairing, and recycling of the material.

  19. Enzymatic biofuel cell based on electrodes modified with lipid liquid-crystalline cubic phases

    Science.gov (United States)

    Nazaruk, Ewa; Smoliński, Sławomir; Swatko-Ossor, Marta; Ginalska, Grażyna; Fiedurek, Jan; Rogalski, Jerzy; Bilewicz, Renata

    Two glassy carbon electrodes modified with enzymes embedded in lyotropic liquid-crystalline cubic phase were used for the biofuel cell construction. The monoolein liquid-crystalline film allowed to avoid separators in the biofuel cell. Glucose and oxygen as fuels, and glucose oxidase and laccase as anode and cathode biocatalysts, respectively were used. The biofuel cell parameters were examined in McIlvaine buffer, pH 7 solution containing 15 mM of glucose and saturated with dioxygen. A series of mediators were tested taking into account their formal potentials, stability in the cubic phase and efficiency of mediation. Most stable was the biofuel cell based on tetrathiafulvalene (TTF) and 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as anode and cathode mediators, respectively. The open-circuit voltage was equal to 450 ± 40 mV. The power densities and current densities were measured for all the systems studied.

  20. Development and evaluation of exemestane-loaded lyotropic liquid crystalline gel formulations

    OpenAIRE

    Musa, Muhammad Nuh; David, Sheba Rani; Zulkipli, Ihsan Nazurah; Mahadi, Abdul Hanif; Chakravarthi, Srikumar; Rajabalaya, Rajan

    2017-01-01

    Introduction: The use of liquid crystalline (LC) gel formulations for drug delivery has considerably improved the current delivery methods in terms of bioavailability and efficacy. The purpose of this study was to develop and evaluate LC gel formulations to deliver the anti-cancer drug exemestane through transdermal route. Methods: Two LC gel formulations were prepared by phase separation coacervation method using glyceryl monooleate (GMO), Tween 80 and Pluronic® F127 (F127). The formulations...

  1. Lattice Boltzmann simulations of liquid crystalline fluids: active gels and blue phases

    OpenAIRE

    Cates, M. E.; Henrich, O.; Marenduzzo, D.; Stratford, K.

    2010-01-01

    Lattice Boltzmann simulations have become a method of choice to solve the hydrodynamic equations of motion of a number of complex fluids. Here we review some recent applications of lattice Boltzmann to study the hydrodynamics of liquid crystalline materials. In particular, we focus on the study of (a) the exotic blue phases of cholesteric liquid crystals, and (b) active gels - a model system for actin plus myosin solutions or bacterial suspensions. In both cases lattice Boltzmann studies have...

  2. Side-chain liquid-crystalline polyesters for optical information storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Andruzzi, F.; Ramanujam, P.S.

    1992-01-01

    We report erasable holographic recording with a resolution of at least 2500 lines/mm on unoriented films of side-chain liquid-crystalline polyesters. Recording energies of approximately 1 J/cm2 have been used. We have obtained a diffraction efficiency of approximately 30% with polarization record...... recording of holograms. The holograms can be erased by heating them to approximately 80-degrees-C for approximately 2 min and are available for rerecording....

  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. Vehicles of inverted hexagonal liquid crystalline lipid phases self-assembled at room temperature

    Czech Academy of Sciences Publication Activity Database

    Angelov, Borislav; Angelova, A.; Garamus, V. M.; Lesieur, S.

    2013-01-01

    Roč. 15, 3/4 (2013), s. 211-215 ISSN 1454-4164 R&D Projects: GA ČR GAP208/10/1600 Institutional support: RVO:61389013 Keywords : liquid crystalline lipid nanoparticles * small angle X-ray scattering * cross-polarised light optical microscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.563, year: 2013 http://joam.inoe.ro/index.php?option=magazine&op=view&idu=3179&catid=76

  5. Liquid crystalline systems for transdermal delivery of celecoxib: in vitro drug release and skin permeation studies.

    Science.gov (United States)

    Estracanholli, Eder André; Praça, Fabíola Silva Garcia; Cintra, Ana Beatriz; Pierre, Maria Bernadete Riemma; Lara, Marilisa Guimarães

    2014-12-01

    Liquid crystalline systems of monoolein/water could be a promising approach for the delivery of celecoxib (CXB) to the skin because these systems can sustain drug release, improve drug penetration into the skin layers and minimize side effects. This study evaluated the potential of these systems for the delivery of CXB into the skin based on in vitro drug release and skin permeation studies. The amount of CXB that permeated into and/or was retained in the skin was assayed using an HPLC method. Polarizing light microscopy studies showed that liquid crystalline systems of monoolein/water were formed in the presence of CXB, without any changes in the mesophases. The liquid crystalline systems decreased drug release when compared to control solution. Drug release was independent of the initial water content of the systems and CXB was released from cubic phase systems, irrespective of the initial water content. The systems released the CXB following zero-order release kinetics. In vitro drug permeation studies showed that cubic phase systems allowed drug permeation and retention in the skin layers. Cubic phase systems of monoolein/water may be promising vehicles for the delivery of CXB in/through the skin because it improved CXB skin permeation compared with the control solution.

  6. From Cellulosic Based Liquid Crystalline Sheared Solutions to 1D and 2D Soft Materials

    Directory of Open Access Journals (Sweden)

    Maria Helena Godinho

    2014-06-01

    Full Text Available Liquid crystalline cellulosic-based solutions described by distinctive properties are at the origin of different kinds of multifunctional materials with unique characteristics. These solutions can form chiral nematic phases at rest, with tuneable photonic behavior, and exhibit a complex behavior associated with the onset of a network of director field defects under shear. Techniques, such as Nuclear Magnetic Resonance (NMR, Rheology coupled with NMR (Rheo-NMR, rheology, optical methods, Magnetic Resonance Imaging (MRI, Wide Angle X-rays Scattering (WAXS, were extensively used to enlighten the liquid crystalline characteristics of these cellulosic solutions. Cellulosic films produced by shear casting and fibers by electrospinning, from these liquid crystalline solutions, have regained wider attention due to recognition of their innovative properties associated to their biocompatibility. Electrospun membranes composed by helical and spiral shape fibers allow the achievement of large surface areas, leading to the improvement of the performance of this kind of systems. The moisture response, light modulated, wettability and the capability of orienting protein and cellulose crystals, opened a wide range of new applications to the shear casted films. Characterization by NMR, X-rays, tensile tests, AFM, and optical methods allowed detailed characterization of those soft cellulosic materials. In this work, special attention will be given to recent developments, including, among others, a moisture driven cellulosic motor and electro-optical devices.

  7. Nonionic diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Sagnella, Sharon M.; Conn, Charlotte E.; Krodkiewska, Irena; Drummond, Calum J. (CSIRO/MSE)

    2014-09-24

    The thermotropic and lyotropic liquid crystalline phase behaviour of a series of diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains (geranoyl, H-farnesoyl, and phytanoyl) has been investigated. When neat, both H-farnesoyl and phytanoyl diethanolamide form a smectic liquid crystalline structure at sub-zero temperatures. In addition, all three diethanolamides exhibit a glass transition temperature at around -73 C. Geranoyl diethanolamide forms a lamellar crystalline phase with a lattice parameter of 17.4 {angstrom} following long term storage accompanied by the loss of the glass transition. In the presence of water, H-farnesoyl and phytanoyl diethanolamide form lyotropic liquid crystalline phases, whilst geranoyl diethanolamide forms an L{sub 2} phase. H-farnesoyl diethanolamide forms a fluid lamellar phase (L{sub {alpha}}) at room temperature and up to {approx} 40 C. Phytanoyl diethanolamide displays a rich mesomorphism forming the inverse diamond (Q{sub II}{sup D}) and gyroid (Q{sub II}{sup G}) bicontinuous cubic phases in addition to an L{sub {alpha}} phase.

  8. Enhanced antitumor efficacy and counterfeited cardiotoxicity of combinatorial oral therapy using Doxorubicin- and Coenzyme Q10-liquid crystalline nanoparticles in comparison with intravenous Adriamycin

    DEFF Research Database (Denmark)

    Swarnakar, Nitin K; Thanki, Kaushik; Jain, Sanyog

    2014-01-01

    and strong synergism for combination at 1:10 dose ratio owing to higher cellular uptake, nuclear colocalization, higher apoptotic index and 8-OHdG levels. The prophylactic antitumor efficacy of the CoQ10-LCNPs was also established using tumor induction and progression studies. Finally, therapeutic antitumor......, with Dox-induced-cardiotoxicity was completely counterfeited in combination. In nutshell, LCNPs pose great potential in improving the therapeutic efficacy of drugs by oral route of administration. FROM THE CLINICAL EDITOR: This study describes the use of liquid crystalline nanoparticles containing coenzyme...

  9. New theories for smectic and nematic liquid-crystal polymers: Backbone LCPs [liquid crystalline polymers] and their mixtures and side-chain LCPs

    International Nuclear Information System (INIS)

    Dowell, F.

    1987-01-01

    A summary of predictions and explanations from statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with backbone LCPs are presented. Trends in the thermodynamic and molecular ordering properties have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. The theoretical results are found to be in good agreement with existing experimental data. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories can be used to design new LCPs and new solvents as well as to predict and explain properties. 27 refs., 4 tabs

  10. 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...

  11. Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

    Science.gov (United States)

    Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

    2012-11-01

    Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

  12. Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxybenzoic Acid

    Directory of Open Access Journals (Sweden)

    Maher A. Qaddoura

    2010-01-01

    Full Text Available The liquid crystalline dimer of 4-(4-pentenyloxybenzoic acid, a member of the n-alkoxybenzoic acid homologous series, was synthesized using potassium carbonate supported on alumina as catalyst. The acid dimer complex exhibited three mesophases; identified as nematic, smectic X1 and smectic X2. Phase transition temperatures and the corresponding enthalpies were recorded using differential scanning calorimetry upon both heating and cooling. The mesophases were identified by detailed texture observations by variable temperature polarized light microscopy. The nematic phase was distinguished by a fluid Schlieren texture and defect points (four and two brushes while the smectic phases were distinguished by rigid marble and mosaic textures, respectively.

  13. Interest of neutron scattering for the investigation of liquid-crystalline polymers

    International Nuclear Information System (INIS)

    Noirez, L.

    1994-01-01

    Small-angle Neutron scattering is the unique method which allows the determination of polymer conformation in the bulk state. This method has been applied to several kinds of liquid crystalline polymers. Results concerning side-chain liquid-crystal polymer, main-chain liquid-crystal polymer and combined liquid-crystal polymers, are reported. It is shown that the polymer conformation is largely dependent on the insertion site of the liquid crystal molecule and of the structure of the meso-phase. (author). 11 refs

  14. Mean-field theory of photoinduced molecular reorientation in azobenzene liquid crystalline side-chain polymers

    DEFF Research Database (Denmark)

    Pedersen, T.G.; Johansen, P.M.

    1997-01-01

    . The theory provides an explanation for the high long-term stability of the photoinduced anisotropy as well as a theoretical prediction of the temporal behavior of photoinduced birefringence. The theoretical results agree favorably with measurements in the entire range of writing intensities used......A novel mean-field theory of photoinduced reorientation and optical anisotropy in liquid crystalline side-chain polymers is presented and compared with experiments, The reorientation mechanism is based on photoinduced trans cis isomerization and a multidomain model of the material is introduced...

  15. Molecular structure of the discotic liquid crystalline phase of hexa-peri-hexabenzocoronene/oligothiophene hybrid and their charge transport properties

    International Nuclear Information System (INIS)

    Bag, Saientan; Maingi, Vishal; Maiti, Prabal K.; Yelk, Joe; Glaser, Matthew A.; Clark, Noel A.; Walba, David M.

    2015-01-01

    Using atomistic molecular dynamics simulation, we study the discotic columnar liquid crystalline (LC) phases formed by a new organic compound having hexa-peri-Hexabenzocoronene (HBC) core with six pendant oligothiophene units recently synthesized by Nan Hu et al. [Adv. Mater. 26, 2066 (2014)]. This HBC core based LC phase was shown to have electric field responsive behavior and has important applications in organic electronics. Our simulation results confirm the hexagonal arrangement of columnar LC phase with a lattice spacing consistent with that obtained from small angle X-ray diffraction data. We have also calculated various positional and orientational correlation functions to characterize the ordering of the molecules in the columnar arrangement. The molecules in a column are arranged with an average twist of 25° having an average inter-molecular separation of ∼5 Å. Interestingly, we find an overall tilt angle of 43° between the columnar axis and HBC core. We also simulate the charge transport through this columnar phase and report the numerical value of charge carrier mobility for this liquid crystal phase. The charge carrier mobility is strongly influenced by the twist angle and average spacing of the molecules in the column

  16. Liquid crystalline systems containing Vitamin E TPGS for the controlled transdermal nicotine delivery

    Directory of Open Access Journals (Sweden)

    Lívia Neves Borgheti-Cardoso

    Full Text Available ABSTRACT Transdermal nicotine patches have been used in smoking cessation therapy, suggested for the treatment of skin disorders with eosinophilic infiltration and have been found to improve attention performance in patients with Alzheimer's disease and age-associated memory impairment. However, skin irritation with extended patch use is still a problem. The aim of this work was to develop a simple to prepare liquid crystalline system containing vitamin E TPGS that would be able to control nicotine delivery and reduce irritation and sensitization problems. The liquid crystalline phases were macroscopically characterized by visual analysis and examined microscopically under a polarized light microscope. Topical and transdermal delivery of nicotine were investigated in vitro using porcine ear skin mounted on a Franz diffusion cell. Nicotine skin permeation from the developed cubic phase followed zero-order kinetics (r = 0.993 and was significantly enhanced after 12 h when compared to the control formulation (nicotine solution (p < 0.05 (138.86 ± 20.44 and 64.91 ± 4.06 μg/cm2, respectively. Cubic phase was also able to target viable skin layers in comparison to control solution (8.18 ± 1.89 and 2.63 ± 2.51 μg/cm2, respectively. Further studies to evaluate skin sensitization and irritation are now necessary.

  17. Highly tilted liquid crystalline materials possessing a direct phase transition from antiferroelectric to isotropic phase

    Energy Technology Data Exchange (ETDEWEB)

    Milewska, K.; Drzewiński, W. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Czerwiński, M., E-mail: mczerwinski@wat.edu.pl [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Dąbrowski, R. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Piecek, W. [Institute of Applied Physics, Military University of Technology, 00-908 Warsaw (Poland)

    2016-03-01

    Pure compounds and multicomponent mixtures with a broad temperature range of high tilted liquid crystalline antiferroelectric phase and a direct phase transition from antiferroelectric to isotropic phase, were obtained. X-ray diffraction analysis confirms these kinds of materials form a high tilted anticlinic phase, with a fixed layer spacing and very weak dependency upon temperature, after the transition from the isotropic phase. Due to this, not only pure orthoconic antiferroelectric liquid crystals but also those with a moderate tilt should generate a good dark state. Furthermore, due to the increased potential for forming anticlinic forces, such materials could minimize a commonly observed asymmetry of a rise and fall switching times at a surface stabilized geometry. - Highlights: • The new class of liquid crystalline materials with the direct SmC{sub A}*. • Iso phase transition were obtained. • Materials possess the layer spacing fixed and very weak dependent upon temperature. • Smectic layers without shrinkage are observed. • A good dark state can be generate in SSAFLC.

  18. Structural aspects of fish skin collagen which forms ordered arrays via liquid crystalline states.

    Science.gov (United States)

    Giraud-Guille, M M; Besseau, L; Chopin, C; Durand, P; Herbage, D

    2000-05-01

    The ability of acid-soluble type I collagen extracts from Soleidae flat fish to form ordered arrays in condensed phases has been compared with data for calf skin collagen. Liquid crystalline assemblies in vitro are optimized by preliminary treatment of the molecular population with ultrasounds. This treatment requires the stability of the fish collagen triple helicity to be controlled by X-ray diffraction and differential scanning calorimetry and the effect of sonication to be evaluated by viscosity measurements and gel electrophoresis. The collagen solution in concentrations of at least 40 mg ml(-1) showed in polarized light microscopy birefringent patterns typical of precholesteric phases indicating long-range order within the fluid collagen phase. Ultrastructural data, obtained after stabilization of the liquid crystalline collagen into a gelated matrix, showed that neutralized acid-soluble fish collagen forms cross-striated fibrils, typical of type I collagen, following sine wave-like undulations in precholesteric domains. These ordered geometries, approximating in vivo situations, give interesting mechanical properties to the material.

  19. Polarized Emission of Wholly Aromatic Bio-Based Copolyesters of a Liquid Crystalline Nature

    Directory of Open Access Journals (Sweden)

    Daisaku Kaneko

    2011-05-01

    Full Text Available A novel thermotropic liquid crystalline polymers poly{3-benzylidene amino-4-hydroxybenzoic acid (3,4-BAHBA-co-trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid} (Poly(3,4-BAHBA-co-4HCA, was synthesized by the thermal polycondensation of 4HCA and 3,4-BAHBA, which was synthesized by a reaction of 3-amino-4-hydroxybenzoic acid (3,4-AHBA with benzaldehyde. When the 4HCA compositions of Poly(3,4-BAHBA-co-4HCAs were above 55 mol%, the copolymers showed a nematic, liquid crystalline phase. Differential scanning calorimetry (DSC measurements of the copolymers showed a high glass transition temperature of more than 100 °C, sufficient for use in engineering plastics. Furthermore, the copolymers showed photoluminescence in an N-methylpyrrolidone (NMP solution under ultraviolet (UV light with a wavelength of 365 nm. Oriented film of Poly(3,4-BAHBA-co-4HCA with a 4HCA composition of 75 mol% emitted polarized light, which was confirmed by fluorescent spectroscopy equipped with parallel and crossed polarizers.

  20. Molecular reorientations in a substance with liquid-crystalline and plastic-crystalline phases

    International Nuclear Information System (INIS)

    Nguyen, Xuan Phuc.

    1986-05-01

    Results of dielectric relaxation (DR), quasielastic neutron scattering (QNS), far infrared absorption (FIR), proton magnetic resonance (PMR), differential scanning calorimetry (DSC) and preliminary X-ray diffraction measurements on the di-n-pentyloxyazoxybenzene (5.OAOB) are presented. The measurements carried out by all these methods showed that 5.OAOB exhibits a nontypical for liquid-crystalline materials phase diagram. It has two mesophases: a nematic (N) and an ''intermediate'' crystalline phase just below it. A complex interpretation of results obtained is given. All suggestions concerning the character of reorientational motions of the molecule as a whole as well as of its segments in mesomorphic phases are analyzed. From comparison of the DR and QNS studies one can conclude that in the N phase the molecule as a whole performs rotational diffusion around the long axis (τ DR ∼ 100 ps) and at the same time the two moieties perform faster independent reorientations around N - benzene rings bonds withτ QNS ∼ 5 ps. On the basis of various experimental data it is shown that the CrI phase is a plastic-crystalline phase for which the molecule and its segments perform fast stochastic unaxial reorientations. This is the first case where the existence of such a phase in liquid-crystalline materials has been experimentally confirmed. (author)

  1. Collagen films with stabilized liquid crystalline phases and concerns on osteoblast behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Minjian; Ding, Shan; Min, Xiang; Jiao, Yanpeng, E-mail: tjiaoyp@jnu.edu.cn; Li, Lihua; Li, Hong; Zhou, Changren, E-mail: tcrz9@jnu.edu.cn

    2016-01-01

    To duplicate collagen's in vivo liquid crystalline (LC) phase and investigate the relationship between the morphology of LC collagen and osteoblast behavior, a self-assembly method was introduced for preparing collagen films with a stabilized LC phase. The LC texture and topological structure of the films before and after stabilization were observed with polarizing optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The relationship between the collagen films and osteoblast behavior was studied with the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide method, proliferation index detection, alkaline phosphatase measurements, osteocalcin assay, inverted microscopy, SEM observation, AFM observation, and cytoskeleton fluorescence staining. The results showed that the LC collagen film had continuously twisting orientations in the cholesteric phase with a typical series of arced patterns. The collagen fibers assembled in a well-organized orientation in the LC film. Compared to the non-LC film, the LC collagen film can promote cell proliferation, and increase ALP and osteocalcin expression, revealing a contact guide effect on osteoblasts. - Highlights: • Collagen film with liquid crystalline (LC) phase was observed by POM, SEM and AFM. • The effect of LC collagen film on osteoblasts behaviors was studied in detail. • LC collagen film promoted osteoblast proliferation and osteogenesis activity.

  2. Synergy in lipofection by cationic lipid mixtures: superior activity at the gel-liquid crystalline phase transition.

    Science.gov (United States)

    Koynova, Rumiana; Wang, Li; MacDonald, Robert C

    2007-07-12

    Some mixtures of two cationic lipids including phospholipid compounds (O-ethylphosphatidylcholines) as well as common, commercially available cationic lipids, such as dimethylammonium bromides and trimethylammonium propanes, deliver therapeutic DNA considerably more efficiently than do the separate molecules. In an effort to rationalize this widespread "mixture synergism", we examined the phase behavior of the cationic lipid mixtures and constructed their binary phase diagrams. Among a group of more than 50 formulations, the compositions with maximum delivery activity resided unambiguously in the solid-liquid crystalline two-phase region at physiological temperature. Thus, the transfection efficacy of formulations exhibiting solid-liquid crystalline phase coexistence is more than 5 times higher than that of formulations in the gel (solid) phase and over twice that of liquid crystalline formulations; phase coexistence occurring at physiological temperature thus appears to contribute significantly to mixture synergism. This relationship between delivery activity and physical property can be rationalized on the basis of the known consequences of lipid-phase transitions, namely, the accumulation of defects and increased disorder at solid-liquid crystalline phase boundaries. Packing defects at the borders of coexisting solid and liquid crystalline domains, as well as large local density fluctuations, could be responsible for the enhanced fusogenicity of mixtures. This study leads to the important conclusion that manipulating the composition of the lipid carriers so that their phase transition takes place at physiological temperature can enhance their delivery efficacy.

  3. Extension of lattice cluster theory to strongly interacting, self-assembling polymeric systems.

    Science.gov (United States)

    Freed, Karl F

    2009-02-14

    A new extension of the lattice cluster theory is developed to describe the influence of monomer structure and local correlations on the free energy of strongly interacting and self-assembling polymer systems. This extension combines a systematic high dimension (1/d) and high temperature expansion (that is appropriate for weakly interacting systems) with a direct treatment of strong interactions. The general theory is illustrated for a binary polymer blend whose two components contain "sticky" donor and acceptor groups, respectively. The free energy is determined as an explicit function of the donor-acceptor contact probabilities that depend, in turn, on the local structure and both the strong and weak interactions.

  4. Viscoelastic Properties of Extracellular Polymeric Substances Can Strongly Affect Their Washing Efficiency from Reverse Osmosis Membranes.

    Science.gov (United States)

    Ferrando Chavez, Diana Lila; Nejidat, Ali; Herzberg, Moshe

    2016-09-06

    The role of the viscoelastic properties of biofouling layers in their removal from the membrane was studied. Model fouling layers of extracellular polymeric substances (EPS) originated from microbial biofilms of Pseudomonas aeruginosa PAO1 differentially expressing the Psl polysaccharide were used for controlled washing experiments of fouled RO membranes. In parallel, adsorption experiments and viscoelastic modeling of the EPS layers were conducted in a quartz crystal microbalance with dissipation (QCM-D). During the washing stage, as shear rate was elevated, significant differences in permeate flux recovery between the three different EPS layers were observed. According to the amount of organic carbon remained on the membrane after washing, the magnitude of Psl production provides elevated resistance of the EPS layer to shear stress. The highest flux recovery during the washing stage was observed for the EPS with no Psl. Psl was shown to elevate the layer's shear modulus and shear viscosity but had no effect on the EPS adhesion to the polyamide surface. We conclude that EPS retain on the membrane as a result of the layer viscoelastic properties. These results highlight an important relation between washing efficiency of fouling layers from membranes and their viscoelastic properties, in addition to their adhesion properties.

  5. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    International Nuclear Information System (INIS)

    Sanchez, C.; Alcala, R.; Hvilsted, S.; Ramanujam, P. S.

    2001-01-01

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution with the sample in darkness. These values are at least two orders of magnitude higher than those previously reported for biphotonic recording. The gratings can be erased with unpolarized blue light and partial recovery of the diffraction efficiency has been observed after the erasure process when the sample is kept in darkness. Red light illumination of the erased film increases the recovered efficiency value and the recovery rate. [copyright] 2001 American Institute of Physics

  6. Evaluation of Microemulsion and Lamellar Liquid Crystalline Systems for Transdermal Zidovudine Delivery.

    Science.gov (United States)

    Carvalho, André Luis Menezes; Silva, José Alexsandro da; Lira, Ana Amélia Moreira; Conceição, Tamara Matos Freire; Nunes, Rogéria de Souza; de Albuquerque Junior, Ricardo Luiz Cavalcanti; Sarmento, Victor Hugo Vitorino; Leal, Leila Bastos; de Santana, Davi Pereira

    2016-07-01

    This study proposed to investigate and to compare colloidal carrier systems containing Zidovudine (3'-azido-3'-deoxythymidine) (AZT) for transdermal administration and optimization of antiretroviral therapy. Microemulsion (ME) and lamellar phase (LP) liquid crystal were obtained and selected from pseudoternary diagrams previously developed. Small-angle X-ray scattering and rheology analysis confirmed the presence of typical ME and liquid crystalline structures with lamellar arrangement, respectively. Both colloidal carrier systems, ME, and LP remained stable, homogeneous, and isotropic after AZT addition. In vitro permeation study (using pig ear skin) showed that the amount of permeated drug was higher for ME compared to the control and LP, obtaining a permeation enhancing effect on the order of approximately 2-fold (p drug permeation without causing apparent skin irritation. On the order hand, LP functioned as a drug reservoir reducing AZT partitioning into the skin. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  7. Sandwich-cell-type bulk-heterojunction organic solar cells utilizing liquid crystalline phthalocyanine

    Science.gov (United States)

    Nakata, Yuya; Usui, Toshiki; Nishikawa, Yuki; Nekelson, Fabien; Shimizu, Yo; Fujii, Akihiko; Ozaki, Masanori

    2018-03-01

    Sandwich-cell-type bulk-heterojunction organic solar cells utilizing the liquid crystalline phthalocyanine, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2), have been fabricated and their photovoltaic properties have been studied. The short-circuit current (J SC) and power conversion efficiency (PCE) depended on the blend ratio of donor and acceptor molecules, and the maximum performance, such as J SC of 3.4 mA/cm2 and PCE of 0.67%, was demonstrated, when the blend ratio of the acceptor was 10 mol %. The photovoltaic properties were discussed by taking the relationship between the column axis direction of C6PcH2 and the carrier mobility in the active layer into consideration.

  8. Temperature-Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix.

    Science.gov (United States)

    Sol, Jeroen A H P; Dehm, Volker; Hecht, Reinhard; Würthner, Frank; Schenning, Albertus P H J; Debije, Michael G

    2018-01-22

    Temperature-responsive luminescent solar concentrators (LSCs) have been fabricated in which the Förster resonance energy transfer (FRET) between a donor-acceptor pair in a liquid crystalline solvent can be tuned. At room temperatures, the perylene bisimide (PBI) acceptor is aggregated and FRET is inactive; while after heating to a temperature above the isotropic phase of the liquid crystal solvent, the acceptor PBI completely dissolves and FRET is activated. This unusual temperature control over FRET was used to design a color-tunable LSC. The device has been shown to be highly stable towards consecutive heating and cooling cycles, making it an appealing device for harvesting otherwise unused solar energy. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  9. LIQUID CRYSTALLINE BEHAVIOR OF HYDROXYPROPYL CELLULOSE ESTERIFIED WITH 4-ALKOXYBENZOIC ACID.

    Directory of Open Access Journals (Sweden)

    Yehia Fahmy

    2010-07-01

    Full Text Available A series of 4- alkyoxybenzoyloxypropyl cellulose (ABPC-n samples was synthesized via the esterification of hydroxypropyl cellulose (HPC with 4-alkoxybenzoic acid bearing different numbers of carbon atoms. The molecular structure of the ABPC-n was confirmed by Fourier transform infrared (FT-IR spectroscopy and 1H NMR spectroscopy. The liquid crystalline (LC phases and transitions behaviors were investigated using differential scanning calorimetry (DSC, polarized light microscopy (PLM, and refractometry. It was found that the glass transition (Tg and clearing (Tc temperatures decrease with increase of the alkoxy chain length. It was observed that the derivatives with an odd number of carbon atoms are non-mesomorphic. This series of ABPC-n polymers exhibit characteristic features of cholesteric LC phases between their glass transition and isotropization temperatures.

  10. Novel side-chain liquid crystalline polyester architecture for reversible optical storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Andruzzi, Fulvio; Kulinna, Chrisian

    1995-01-01

    New side-chain liquid crystalline polyesters have been prepared by melt transesterification of diphenyl tetradecanedioate and a series of mesogenic 2-[omega-[4-[(4-cyanophenyl)azo]phenoxyl] alkyl]-1,3-propanediols, where the alkyl spacer is hexa-, octa-, and decamethylene in turn. The polyesters...... have molecular masses in the range 5000-89 000. Solution C-13 NMR spectroscopy has been employed to identify carbons of polyester repeat units and of both types of end groups. Polyester phases and phase transitions have been investigated in detail by polarizing optical microscopy and differential...... scanning calorimetry for the hexamethylene spacer architecture with different molecular masses. Using FTIR polarization spectroscopy, the segmental orientation in unoriented polyester films induced by argon ion laser irradiation has been followed and an irradiation-dependent order parameter...

  11. Azobenzene side-chain liquid crystalline polyesters with outstanding optical storage properties

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Pedersen, M; Holme, NCR

    1998-01-01

    A flexible azobenzene side-chain liquid crystalline (SCLC) polyester architecture employed for reversible optical storage is described. The modular design allows four structural parameters to be individually modified. These parameters: i- the methylene side-chain spacer length, ii- the substituent......,000 are routinely obtained by melt transesterification of the novel diols and selected diacid precursors (parameter iii). Prominent storage features include no prealignment of thin SCLC polyester films prior to the writing process, and sensitivity in a broad laser wavelength window (415-532 nm). Additionally...... sign of fatigue. The non-destructive read out is performed with red light (600-750 nm). Finally, erasing the information can be achieved by heating the polyester film to 80 degrees C or irradiating it briefly with UV-light. In the latter case at least 10,000 write, read and erase cycles are possible...

  12. Nanostructured liquid crystalline particles as an alternative delivery vehicle for plant agrochemicals.

    Science.gov (United States)

    Nadiminti, Pavani P; Dong, Yao D; Sayer, Chad; Hay, Phillip; Rookes, James E; Boyd, Ben J; Cahill, David M

    2013-03-13

    Agrochemical spray formulations applied to plants are often mixed with surfactants that facilitate delivery of the active ingredient. However, surfactants cause phytotoxicity and off-target effects in the environment. We propose the use of nanostructured liquid crystalline particles (NLCP) as an alternative to surfactant-based agrochemical delivery. For this, we have compared the application of commercial surfactants, di (2-ethylhexyl) sulfosuccinate and alkyl dimethyl betaine, with NLCP made from phytantriol, at concentrations of 0.1%, 1% and 5% on the adaxial surface of leaves of four plant species Ttriticum aestivum (wheat), Zea mays (maize), Lupinus angustifolius (lupin), and Arabidopsis thaliana. In comparison with the application of surfactants there was less phytotoxicity on leaves of each species following treatment with NLCP. Following treatment of leaves with NLCP analysis of cuticular wax micromorphology revealed less wax solubilization in the monocot species. The results clearly show that there are advantages in the use of NLCP rather than surfactants for agrochemical delivery.

  13. New theory for competing interactions and microstructures in partially-ordered (liquid-crystalline) phases

    International Nuclear Information System (INIS)

    Dowell, F.

    1987-01-01

    A summary of results from a unique statistical-physics theory to predict and explain competing interactions and resulting microstructures in some partially-ordered [in this case, liquid-crystalline (LC)] phases is presented. The static aspects of both partial orientational and partial positional ordering of the molecules into various microstructures in these phases (including the incommensurate smectic-Ad phase) can be understood in terms of various competing interactions (both entropic and energetic) involved in the packing together of the different molecular sub-units at given pressures and temperatures. These microstructures are predicted and explained (using no ad hoc or arbitrarily adjustable parameter) as a function of molecule chemical structure [including lengths and shapes (from bond lengths and angles), intramolecular rotations, site-site polarizabilities and pair potentials, dipole moments, etc]. Theoretical results are presented for the nematic, re-entrant nematic, smectic-Ad, and smectic-Al LC phases and the isotropic phase

  14. New liquid crystalline materials based on two generations of dendronised cyclophosphazenes.

    Science.gov (United States)

    Jiménez, Josefina; Laguna, Antonio; Gascón, Elena; Sanz, José Antonio; Serrano, José Luis; Barberá, Joaquín; Oriol, Luis

    2012-12-21

    A divergent approach was used for the synthesis of dendritic structures based on a cyclotriphosphazene core with 12 or 24 hydroxyl groups, by starting from [N(3)P(3)(OC(6)H(4)OH-4)(6)] and using an acetal-protected 2,2-di(hydroxymethyl)propionic anhydride as the acylating agent. Hydroxyl groups in these first- and second-generation dendrimers, G1-(OH)(12) or G2-(OH)(24), were then condensed in turn with mono- or polycatenar pro-mesogenic acids to study their ability to promote self-assembly into liquid crystalline structures. Reactions were monitored by using (31)P{(1)H} and (1)H NMR spectroscopy and the chemical structure of the resulting materials was confirmed by using different spectroscopic techniques and mass spectrometry (MALDI-TOF MS). The results were in accordance with monodisperse, fully functionalised cyclotriphosphazene dendrimers. Thermal and liquid crystalline properties were studied by using optical microscopy, differential scanning calorimetry and X-ray diffraction. The dendrimer with 12 4-pentylbiphenyl mesogenic units gives rise to columnar rectangular organisation, whereas the one with 24 pentylbiphenyl units does not exhibit mesomorphic behaviour. In the case of materials that contain polycatenar pro-mesogenic units with two aromatic rings (A4 vs. A5), the incorporation of a short flexible spacer connected to the periphery of the dendron (acid A5) was needed to achieve mesomorphic organisation. In this case, both dendrimer generations G1 A5 and G2 A5 exhibit a hexagonal columnar mesophase. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Cubic liquid crystalline nanoparticles containing a polysaccharide from Ulva fasciata with potent antihyperlipidaemic activity

    Directory of Open Access Journals (Sweden)

    Azza A. Matloub

    2018-02-01

    Full Text Available The present study involves the preparation of cubic liquid crystalline nanoparticles (cubsomes for liver targeting to assess the potential of a formulated bioactive polysaccharide isolated from the hot aqueous extract of Ulva fasciata as an alternative natural agent with anti-hyperlipidaemic activity. Cubosomal nanoparticles were prepared by disrupting the cubic gel phase of the polysaccharide and water in the presence of a surfactant. Different lipid matrices and stabilizers were tested. All the formulations were in the nanosize range and showed sufficient negative charge to inhibit the aggregation of the cubosomes. Drug entrapment efficiencies (EEs% were determined and in vitro release studies were performed. Transmission electron microscopy (TEM and differential scanning calorimetry were used to analyze the loaded cubosomal nanoparticles containing glyceryl monostearate (GMO 2.25 g, poloxamer 407 (0.25 g and 50 mg of the polysaccharide. A preclinical study comparing the cubic liquid crystalline nanoparticles containing polysaccharide to fluvastatin as a reference drug in hyperlipidaemic rats was conducted. The rats treated with the polysaccharide- loaded cubosomes showed significant decreases in total cholesterol (TC, triglycerides (TG and total lipid (TL compared to the untreated HL rats. In addition, oxidative stress and antioxidant biomarkers were measured in the HL rats. Compared to the untreated HL rats, the cubosome treated rats showed a significant reduction in malondialdehyde (MDA, whereas insignificant changes were detected in nitric oxide (NO, glutathione (GSH levels and total antioxidant capacity (TAC. Further, vascular and intercellular adhesion molecules (VCAM, ICAM, and myeloperoxidase were demonstrated. A histopathological examination was conducted to study the alterations in histopathological lesions and to document the biochemical results. In conclusion, this study demonstrates the superiority of using a natural lipid

  16. Influence of the nematic order on the rheology and conformation of stretched comb-like liquid crystalline polymers

    Science.gov (United States)

    Fourmaux-Demange, V.; Brûlet, A.; Boué, F.; Davidson, P.; Keller, P.; Cotton, J. P.

    2000-04-01

    We have studied the rheology and the conformation of stretched comb-like liquid-crystalline polymers. Both the influence of the comb-like structure and the specific effect of the nematic interaction on the dynamics are investigated. For this purpose, two isomers of a comb-like polymetacrylate polymer, of well-defined molecular weights, were synthesized: one displays a nematic phase over a wide range of temperature, the other one has only an isotropic phase. Even with high degrees of polymerization N, between 40 and 1000, the polymer chains studied were not entangled. The stress-strain curves during the stretching and relaxation processes show differences between the isotropic and nematic comb-like polymers. They suggest that, in the nematic phase, the chain dynamics is more cooperative than for a usual linear polymer. Small-angle neutron scattering has been used in order to determine the evolution of the chain conformation after stretching, as a function of the duration of relaxation t_r. The conformation can be described with two parameters only: λ_p, the global deformation of the polymer chain, and p, the number of statistical units of locally relaxed sub-chains. For the comb-like polymer, the chain deformation is pseudo-affine: λ_p is always smaller than λ (the deformation ratio of the whole sample). In the isotropic phase, λ_p has a constant value, while p increases as t_r. This latter behavior is not that expected for non-entangled chains, in which p varies as {t_r}^{1/2} (Rouse model). In the nematic phase, λ_p decreases as a stretched exponential function of t_r, while p remains constant. The dynamics of the comb-like polymers is discussed in terms of living clusters from which junctions are produced by interactions between side chains. The nematic interaction increases the lifetime of these junctions and, strikingly, the relaxation is the same at all scales of the whole polymer chain.

  17. The effect of glassfibre, graphite and MoS2 on the tribological performance of a liquid crystalline polymer

    NARCIS (Netherlands)

    Dufour, P.R.; de Gee, A.W.J.; Kingma, J.A.; Mens, J.W.M.

    1992-01-01

    A thermotropic liquid crystalline polymer (LCP) with a high melting point of approximately 400 °C, unfilled and filled with glassfibre, MoS2 or graphitic carbon was tested in dry sliding contact with steel. Three different test methods were applied, i.e. measurement of coefficient of friction and

  18. Novel lecithin-integrated liquid crystalline nanogels for enhanced cutaneous targeting of terconazole: development, in vitro and in vivo studies

    Science.gov (United States)

    Elnaggar, Yosra SR; Talaat, Sara M; Bahey-El-Din, Mohammed; Abdallah, Ossama Y

    2016-01-01

    Terconazole (Tr) is the first marketed, most active triazole for vaginal candidiasis. Owing to poor skin permeation and challenging physicochemical properties, Tr was not employed for the treatment of cutaneous candidiasis. This is the first study to investigate the relevance of novel lecithin-integrated liquid crystalline nano-organogels (LCGs) to improve physicochemical characteristics of Tr in order to enable its dermal application in skin candidiasis. Ternary phase diagram was constructed using lecithin/capryol 90/water to identify the region of liquid crystalline organogel. The selected organogel possessed promising physicochemical characteristics based on particle size, rheological behavior, pH, loading efficiency, and in vitro antifungal activity. Microstructure of the selected organogel was confirmed by polarized light microscopy and transmission electron microscopy. Ex vivo and in vivo skin permeation studies revealed a significant 4.7- and 2.7-fold increase in the permeability of Tr-loaded LCG when compared to conventional hydrogel. Moreover, acute irritation study indicated safety and compatibility of liquid crystalline organogel to the skin. The in vivo antifungal activity confirmed the superiority of LCG over the conventional hydrogel for the eradication of Candida infection. Overall, lecithin-based liquid crystalline organogel confirmed its potential as an interesting dermal nanocarrier for skin targeting purpose. PMID:27822033

  19. Novel lecithin-integrated liquid crystalline nanogels for enhanced cutaneous targeting of terconazole: development, in vitro and in vivo studies.

    Science.gov (United States)

    Elnaggar, Yosra Sr; Talaat, Sara M; Bahey-El-Din, Mohammed; Abdallah, Ossama Y

    Terconazole (Tr) is the first marketed, most active triazole for vaginal candidiasis. Owing to poor skin permeation and challenging physicochemical properties, Tr was not employed for the treatment of cutaneous candidiasis. This is the first study to investigate the relevance of novel lecithin-integrated liquid crystalline nano-organogels (LCGs) to improve physicochemical characteristics of Tr in order to enable its dermal application in skin candidiasis. Ternary phase diagram was constructed using lecithin/capryol 90/water to identify the region of liquid crystalline organogel. The selected organogel possessed promising physicochemical characteristics based on particle size, rheological behavior, pH, loading efficiency, and in vitro antifungal activity. Microstructure of the selected organogel was confirmed by polarized light microscopy and transmission electron microscopy. Ex vivo and in vivo skin permeation studies revealed a significant 4.7- and 2.7-fold increase in the permeability of Tr-loaded LCG when compared to conventional hydrogel. Moreover, acute irritation study indicated safety and compatibility of liquid crystalline organogel to the skin. The in vivo antifungal activity confirmed the superiority of LCG over the conventional hydrogel for the eradication of Candida infection. Overall, lecithin-based liquid crystalline organogel confirmed its potential as an interesting dermal nanocarrier for skin targeting purpose.

  20. 10,000 optical write, read, and erase cycles in an azobenzene sidechain liquid-crystalline polyester

    DEFF Research Database (Denmark)

    Holme, NCR; Ramanujam, P.S.; Hvilsted, Søren

    1996-01-01

    We show far what is believed to he the first time that it is possible tu generate 10,000 rapid write, read, and erase cycles optically in an azobenzene sidechain liquid-crystalline polyester. We do this by exposing the film alternately to visible light from an argon laser at 488 nm and ultraviolet...

  1. Synthesis and Supramolecular Chemistry of Novel Liquid Crystalline Crown Ether-Substituted Phthalocyanines : Toward Molecular Wires and Molecular Ionoelectronics

    NARCIS (Netherlands)

    Nostrum, Cornelus F. van; Picken, Stephen J.; Schouten, Arend-Jan; Nolte, Roeland J.M.

    1995-01-01

    The synthesis of the metal-free and the dihydroxysilicon derivatives of tetrakis[4’,5’-bis(decoxy)benzo-18-crown-6]phthalocyanine is described. The metal-free phthalocyanine is liquid crystalline and exhibits a crystalline phase to mesophase transition at 148 °C. The structures of the crystalline

  2. 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

  3. Novel lecithin-integrated liquid crystalline nanogels for enhanced cutaneous targeting of terconazole: development, in vitro and in vivo studies

    Directory of Open Access Journals (Sweden)

    Elnaggar YSR

    2016-10-01

    Full Text Available Yosra SR Elnaggar,1,2 Sara M Talaat,1 Mohammed Bahey-El-Din,3 Ossama Y Abdallah1 1Department of Pharmaceutics, Faculty of Pharmacy, Alexandria University, 2Department of Pharmaceutics, Faculty of Pharmacy and Drug Manufacturing, Pharos University in Alexandria, 3Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt Abstract: Terconazole (Tr is the first marketed, most active triazole for vaginal candidiasis. Owing to poor skin permeation and challenging physicochemical properties, Tr was not employed for the treatment of cutaneous candidiasis. This is the first study to investigate the relevance of novel lecithin-integrated liquid crystalline nano-organogels (LCGs to improve physicochemical characteristics of Tr in order to enable its dermal application in skin candidiasis. Ternary phase diagram was constructed using lecithin/capryol 90/water to identify the region of liquid crystalline organogel. The selected organogel possessed promising physicochemical characteristics based on particle size, rheological behavior, pH, loading efficiency, and in vitro antifungal activity. Microstructure of the selected organogel was confirmed by polarized light microscopy and transmission electron microscopy. Ex vivo and in vivo skin permeation studies revealed a significant 4.7- and 2.7-fold increase in the permeability of Tr-loaded LCG when compared to conventional hydrogel. Moreover, acute irritation study indicated safety and compatibility of liquid crystalline organogel to the skin. The in vivo antifungal activity confirmed the superiority of LCG over the conventional hydrogel for the eradication of Candida infection. Overall, lecithin-based liquid crystalline organogel confirmed its potential as an interesting dermal nanocarrier for skin targeting purpose. Keywords: terconazole, liquid crystalline, organogel, skin targeting, skin mycosis

  4. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study.

    Science.gov (United States)

    Workineh, Zerihun G; Vanakaras, Alexandros G

    2016-03-23

    In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2-3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.

  5. Lyotropic liquid crystalline phase behaviour in amphiphile-protic ionic liquid systems.

    Science.gov (United States)

    Chen, Zhengfei; Greaves, Tamar L; Fong, Celesta; Caruso, Rachel A; Drummond, Calum J

    2012-03-21

    Approximate partial phase diagrams for nine amphiphile-protic ionic liquid (PIL) systems have been determined by synchrotron source small angle X-ray scattering, differential scanning calorimetry and cross polarised optical microscopy. The binary phase diagrams of some common cationic (hexadecyltrimethyl ammonium chloride, CTAC, and hexadecylpyridinium bromide, HDPB) and nonionic (polyoxyethylene (10) oleyl ether, Brij 97, and Pluronic block copolymer, P123) amphiphiles with the PILs, ethylammonium nitrate (EAN), ethanolammonium nitrate (EOAN) and diethanolammonium formate (DEOAF), have been studied. The phase diagrams were constructed for concentrations from 10 wt% to 80 wt% amphiphile, in the temperature range 25 °C to >100 °C. Lyotropic liquid crystalline phases (hexagonal, cubic and lamellar) were formed at high surfactant concentrations (typically >50 wt%), whereas at thermal stability of the phases formed by these surfactants persisted to temperatures above 100 °C. The phase behaviour of amphiphile-PIL systems was interpreted by considering the PIL cohesive energy, liquid nanoscale order, polarity and ionicity. For comparison the phase behaviour of the four amphiphiles was also studied in water.

  6. Direct Visualisation of the Structural Transformation between the Lyotropic Liquid Crystalline Lamellar and Bicontinuous Cubic Mesophase.

    Science.gov (United States)

    Tran, Nhiem; Zhai, Jiali; Conn, Charlotte E; Mulet, Xavier; Waddington, Lynne J; Drummond, Calum J

    2018-05-29

    The transition between the lyotropic liquid crystalline lamellar and the bicontinuous cubic mesophase drives multiple fundamental cellular processes involving changes in cell membrane topology including endocytosis and membrane budding. While several theoretical models have been proposed to explain this dynamic transformation, experimental validation of these models has been challenging due to the short lived nature of the intermediates present during the phase transition. Herein, we report the direct observation of a lamellar to bicontinuous cubic phase transition in nanoscale dispersions using a combination of cryogenic transmission electron microscopy and static small angle X-ray scattering. The results represent the first experimental confirmation of a theoretical model which proposed that the bicontinuous cubic phase originates from the centre of a lamellar vesicle, then propagates outward via the formation of inter-lamellar attachments and stalks. The observation was possible due to the precise control of the lipid composition to place the dispersion systems at the phase boundary of a lamellar and a cubic phase, allowing for the creation of long-lived structural intermediates. By surveying the nanoparticles using cryogenic transmission electron microscopy, a complete phase transition sequence was established.

  7. Hydrogen Bond Induces Hierarchical Self-Assembly in Liquid-Crystalline Block Copolymers.

    Science.gov (United States)

    Huang, Shuai; Pang, Linlin; Chen, Yuxuan; Zhou, Liming; Fang, Shaoming; Yu, Haifeng

    2018-03-01

    Microphase-separated structures of block copolymers (BCs) with a size of sub-10 nm are usually obtained by hydrogen-bond-induced self-assembly of BCs through doping with small molecules as functional additives. Here, fabrication of hierarchically self-assembled sub-10 nm structures upon microphase separation of amphiphilic liquid-crystalline BCs (LCBCs) at the existence of hydrogen bonds but without any dopants is reported. The newly introduced urethane groups in the side chain of the hydrophobic block of LCBCs interact with the ether groups of the hydrophilic poly(ethylene oxide) (PEO) block, leading to imperfect crystallization of the PEO blocks. Both crystalline and amorphous domains coexist in the separated PEO phase, enabling a lamellar structure to appear inside the PEO nanocylinders. This provides an elegant method to fabricate controllable sub-10 nm microstructures in well-defined polymer systems without the introduction of any dopants. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Lipid-Based Liquid Crystalline Nanoparticles Facilitate Cytosolic Delivery of siRNA via Structural Transformation.

    Science.gov (United States)

    He, Shufang; Fan, Weiwei; Wu, Na; Zhu, Jingjing; Miao, Yunqiu; Miao, Xiaran; Li, Feifei; Zhang, Xinxin; Gan, Yong

    2018-04-11

    RNA interference (RNAi) technology has shown great promise for the treatment of cancer and other genetic disorders. Despite the efforts to increase the target tissue distribution, the safe and effective delivery of siRNA to the diseased cells with sufficient cytosolic transport is another critical factor for successful RNAi clinical application. Here, the constructed lipid-based liquid crystalline nanoparticles, called nano-Transformers, can transform thestructure in the intracellular acidic environment and perform high-efficient siRNA delivery for cancer treatment. The developed nano-Transformers have satisfactory siRNA loading efficiency and low cytotoxicity. Different from the traditional cationic nanocarriers, the endosomal membrane fusion induced by the conformational transition of lipids contributes to the easy dissociation of siRNA from nanocarriers and direct release of free siRNA into cytoplasm. We show that transfection with cyclin-dependent kinase 1 (CDK1)-siRNA-loaded nano-Transformers causes up to 95% reduction of relevant mRNA in vitro and greatly inhibits the tumor growth without causing any immunogenic response in vivo. This work highlights that the lipid-based nano-Transformers may become the next generation of siRNA delivery system with higher efficacy and improved safety profiles.

  9. Liquid crystalline phase as a probe for crystal engineering of lactose: carrier for pulmonary drug delivery.

    Science.gov (United States)

    Patil, Sharvil S; Mahadik, Kakasaheb R; Paradkar, Anant R

    2015-02-20

    The current work was undertaken to assess suitability of liquid crystalline phase for engineering of lactose crystals and their utility as a carrier in dry powder inhalation formulations. Saturated lactose solution was poured in molten glyceryl monooleate which subsequently transformed into gel. The gel microstructure was analyzed by PPL microscopy and SAXS. Lactose particles recovered from gels after 48 h were analyzed for polymorphism using techniques such as FTIR, XRD, DSC and TGA. Particle size, morphology and aerosolisation properties of prepared lactose were analyzed using Anderson cascade impactor. In situ seeding followed by growth of lactose crystals took place in gels with cubic microstructure as revealed by PPL microscopy and SAXS. Elongated (size ∼ 71 μm) lactose particles with smooth surface containing mixture of α and β-lactose was recovered from gel, however percentage of α-lactose was more as compared to β-lactose. The aerosolisation parameters such as RD, ED, %FPF and % recovery of lactose recovered from gel (LPL) were found to be comparable to Respitose® ML001. Thus LC phase (cubic) can be used for engineering of lactose crystals so as to obtain particles with smooth surface, high elongation ratio and further they can be used as carrier in DPI formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Mesophase and size manipulation of itraconazole liquid crystalline nanoparticles produced via quasi nanoemulsion precipitation.

    Science.gov (United States)

    Mugheirbi, Naila A; Tajber, Lidia

    2015-10-01

    The fabrication of drug nanoparticles (NPs) with process-mediated tunable properties and performances continues to grow rapidly during the last decades. This study investigates the synthesis and phase tuning of nanoparticulate itraconazole (ITR) mesophases using quasi nanoemulsion precipitation from acetone/water systems to seek out an alternative pathway to the nucleation-based NP formation. ITR liquid crystalline (LC) phases were formed and nematic-smectic mesomorphism was achieved via controlling solvent:antisolvent temperature difference (ΔTS:AS). The use of ΔTS:AS=49.5°C was associated with a nematic assembly, while intercalated smectic A layering was observed at ΔTS:AS=0°C, with both phases confined in the nanospheres at room temperature. The quasi emulsion system has not been investigated at the nanoscale to date and in contrary to the microscale, quasi nanoemulsion was observed over the solvent:antisolvent viscosity ratios of 1:7-1:1.4. Poly(acrylic acid) in the solvent phase exhibited a concentration dependent interaction when ITR formed NPs. This nanodroplet-based approach enabled the preparation of a stable ITR nanodispersion using Poloxamer 407 at 80°C, which was unachievable before using precipitation via nucleation. Findings of this work lay groundwork in terms of rationalised molecular assembly as a tool in designing pharmaceutical LC NPs with tailored properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Macromolecular crowding-assisted fabrication of liquid-crystalline imprinted polymers.

    Science.gov (United States)

    Zhang, Chen; Zhang, Jing; Huang, Yan-Ping; Liu, Zhao-Sheng

    2015-04-01

    A macromolecular crowding-assisted liquid-crystalline molecularly imprinted monolith (LC-MIM) was prepared successfully for the first time. The imprinted stationary phase was synthesized with polymethyl methacrylate (PMMA) or polystyrene (PS) as the crowding agent, 4-cyanophenyl dicyclohexyl propylene (CPCE) as the liquid-crystal monomer, and hydroquinidine as the pseudo-template for the chiral separation of cinchona alkaloids in HPLC. A low level of cross-linker (26%) has been found to be sufficient to achieve molecular recognition on the crowding-assisted LC-MIM due to the physical cross-linking of mesogenic groups in place of chemical cross-linking, and baseline separation of quinidine and quinine could be achieved with good resolution (R(s) = 2.96), selectivity factor (α = 2.16), and column efficiency (N = 2650 plates/m). In contrast, the LC-MIM prepared without crowding agents displayed the smallest diastereoselectivity (α = 1.90), while the crowding-assisted MIM with high level of cross-linker (80%) obtained the greatest selectivity factor (α = 7.65), but the lowest column efficiency (N = 177 plates/m).

  12. Distance-dependent metal enhanced fluorescence by flowerlike silver nanostructures fabricated in liquid crystalline phase

    Science.gov (United States)

    Zhang, Ying; Yang, Chengliang; Zhang, Guiyang; Peng, Zenghui; Yao, Lishuang; Wang, Qidong; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

    2017-10-01

    Flowerlike silver nanostructure substrates were fabricated in liquid crystalline phase and the distance dependent property of metal enhanced fluorescence for such substrate was studied for the first time. The distance between silver nanostructures and fluorophore was controlled by the well-established layer-by-layer (LbL) technique constructing alternate layers of poly (allylamine hydrochloride) (PAH) and poly (sodium 4-styrenesulfonate) (PSS). The Rhodamine 6G (R6G) molecules were electrostatically attached to the outmost negative charged PSS layer. The fluorescence enhancement factor of flowerlike nanostructure substrate increased firstly and then decreased with the distance increasing. The best enhanced fluorescence intensity of 71 fold was obtained at a distance of 5.2 nm from the surface of flowerlike silver nanostructure. The distance for best enhancement effect is an instructive parameter for the applications of such substrates and could be used in the practical MEF applications with the flowerlike nanostructure substrates fabricated in such way which is simple, controllable and cost-effective.

  13. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study

    Science.gov (United States)

    Workineh, Zerihun G.; Vanakaras, Alexandros G.

    2016-03-01

    In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2-3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.

  14. Lyotropic Liquid Crystalline Nanoparticles of Amphotericin B: Implication of Phytantriol and Glyceryl Monooleate on Bioavailability Enhancement.

    Science.gov (United States)

    Jain, Sanyog; Yadav, Pooja; Swami, Rajan; Swarnakar, Nitin Kumar; Kushwah, Varun; Katiyar, Sameer S

    2018-05-01

    Implication of different dietary specific lipids such as phytantriol (PT) and glyceryl monooleate (GMO) on enhancing the oral bioavailability of amphotericin B (AmB) was examined. Liquid crystalline nanoparticles (LCNPs) were prepared using hydrotrope method, followed by in vitro characterization, Caco-2 cell monolayer uptake, and in vivo pharmacokinetic and toxicity evaluation. Optimized AmB-LCNPs displayed small particle size (< 210 nm) with a narrow distribution (~ 0.2), sustained drug release and high gastrointestinal stability, and reduced hemolytic toxicity. PLCNPs presented slower release, i.e., ~ 80% as compared to ~ 90% release in case of GLCNPs after 120 h. Significantly higher uptake in Caco-2 monolayer substantiated the role of LCNPs in increasing the intestinal permeability followed by increased drug titer in plasma. Pharmacokinetic studies demonstrated potential of PT in enhancing the bioavailability (approximately sixfold) w.r.t. of its native counterpart with reduced nephrotoxicity as presented by reduced nephrotoxicity biomarkers and histology studies. These studies established usefulness of PLCNPs over GLCNPs and plain drug. It can be concluded that acid-resistant lipid, PT, can be utilized efficiently as an alternate lipid for the preparation of LCNPs to enhance bioavailability and to reduce nephrotoxicity of the drug as compared to other frequently used lipid, i.e., GMO.

  15. Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

    Energy Technology Data Exchange (ETDEWEB)

    Conn, Charlotte E.; Panchagnula, Venkateswarlu; Weerawardena, Asoka; Waddington, Lynne J.; Kennedy, Danielle F.; Drummond, Calum J. (CSIRO/MHT); (CSIRO/MSE)

    2010-08-23

    Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.

  16. Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

    International Nuclear Information System (INIS)

    Conn, Charlotte E.; Panchagnula, Venkateswarlu; Weerawardena, Asoka; Waddington, Lynne J.; Kennedy, Danielle F.; Drummond, Calum J.

    2010-01-01

    Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.

  17. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study

    International Nuclear Information System (INIS)

    Workineh, Zerihun G; Vanakaras, Alexandros G

    2016-01-01

    In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2–3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2–3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape. (paper)

  18. Supramolecular liquid crystalline π-conjugates: the role of aromatic π-stacking and van der Waals forces on the molecular self-assembly of oligophenylenevinylenes.

    Science.gov (United States)

    Goel, Mahima; Jayakannan, M

    2010-10-07

    Here, we report a unique design strategy to trace the role of aromatic π-stacking and van der Waals interactions on the molecular self-organization of π-conjugated building blocks in a single system. A new series of bulky oligophenylenevinylenes (OPVs) bearing a tricyclodecanemethylene (TCD) unit in the aromatic π-core with flexible long methylene chains (n = 0-12 and 16) in the longitudinal position were designed and synthesized. The OPVs were found to be liquid crystalline, and their enthalpies of phase transitions (also entropies) showed odd-even oscillation with respect to the number of carbon atoms in alkyl chains. OPVs with an even number of methylene units in the side chains showed higher enthalpies with respect to their highly packed solid structures compared to odd-numbered ones. Polarized light microscopic analysis confirmed the formation of cholesteric liquid crystalline (LC) phases of fan shaped textures with focal conics in OPVs with 5 ≤ n ≤ 9. OPVs with longer alkyl chains (OPV-10 to OPV-12) produced a birefringence pattern consisting of dark and bright ring-banded suprastructures. The melting temperature followed a sigmoidal trend, indicating the transformation of molecular self-organization in OPVs from solid to ring-banded suprastructures via cholesteric LC intermediates. At longer alkyl chain lengths, the van der Waals interactions among the alkyl chains became predominant and translated the mesogenic effect across the lamellae; as a consequence, the lamellae underwent twisted self-organization along the radial growth direction of the spherulites to produce bright and dark bands. Scanning electron microscope (SEM) analysis of cholesteric LC and ring-banded textures strongly supported the existence of twisted lamellae in the OPVs with ring-banded textures. Variable temperature X-ray diffraction analysis confirmed the reversibility of the molecular self-organization in the solid state and also showed the existence of the higher ordered

  19. Blending crystalline/liquid crystalline small molecule semiconductors: A strategy towards high performance organic thin film transistors

    Science.gov (United States)

    He, Chao; He, Yaowu; Li, Aiyuan; Zhang, Dongwei; Meng, Hong

    2016-10-01

    Solution processed small molecule polycrystalline thin films often suffer from the problems of inhomogeneity and discontinuity. Here, we describe a strategy to solve these problems through deposition of the active layer from a blended solution of crystalline (2-phenyl[1]benzothieno[3,2-b][1]benzothiophene, Ph-BTBT) and liquid crystalline (2-(4-dodecylphenyl) [1]benzothieno[3,2-b]benzothiophene, C12-Ph-BTBT) small molecule semiconductors with the hot spin-coating method. Organic thin film transistors with average hole mobility approaching 1 cm2/V s, much higher than that of single component devices, have been demonstrated, mainly due to the improved uniformity, continuity, crystallinity, and stronger intermolecular π-π stacking in blend thin films. Our results indicate that the crystalline/liquid crystalline semiconductor blend method is an effective way to enhance the performance of organic transistors.

  20. Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

    OpenAIRE

    Saed, Mohand O.; Torbati, Amir H.; Nair, Devatha P.; Yakacki, Christopher M.

    2016-01-01

    This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addi...

  1. Liquid-crystalline polyesters with end nitroxyl radical and their use in living free-radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Razina, A B.; Sedláková, Zdeňka; Bouchal, Karel; Tenkovtsev, A. V.; Ilavský, Michal

    2002-01-01

    Roč. 44, č. 9 (2002), s. 924-930 ISSN 0965-545X R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : liquid crystal * polyesters * nitroxyl radical Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.627, year: 2002

  2. Emergence of liquid crystalline order in the lowest Landau level of a quantum Hall system with internal anisotropy

    Science.gov (United States)

    Ciftja, Orion

    2018-05-01

    It has now become evident that interplay between internal anisotropy parameters (such as electron mass anisotropy and/or anisotropic coupling of electrons to the substrate) and electron-electron correlation effects can create a rich variety of possibilities especially in quantum Hall systems. The electron mass anisotropy or material substrate effects (for example, the piezoelectric effect in GaAs) can lead to an effective anisotropic interaction potential between electrons. For lack of knowledge of realistic ab-initio potentials that may describe such effects, we adopt a phenomenological approach and assume that an anisotropic Coulomb interaction potential mimics the internal anisotropy of the system. In this work we investigate the emergence of liquid crystalline order at filling factor ν = 1/6 of the lowest Landau level, a state very close to the point where a transition from the liquid to the Wigner solid happens. We consider small finite systems of electrons interacting with an anisotropic Coulomb interaction potential and study the energy stability of an anisotropic liquid crystalline state relative to its isotropic Fermi-liquid counterpart. Quantum Monte Carlo simulation results in disk geometry show stabilization of liquid crystalline order driven by an anisotropic Coulomb interaction potential at all values of the interaction anisotropy parameter studied.

  3. Numerical evidence of liquid crystalline mesophases of a lollipop shaped model in two dimensions

    Science.gov (United States)

    Pérez-Lemus, G. R.; Armas-Pérez, J. C.; Chapela, G. A.; Quintana-H., J.

    2017-12-01

    Small alterations in the molecular details may produce noticeable changes in the symmetry of the resulting phase behavior. It is possible to produce morphologies having different n-fold symmetries by manipulating molecular features such as chirality, polarity or anisotropy. In this paper, a two dimensional hard molecular model is introduced to study the formation of liquid crystalline phases in low dimensionality. The model is similar to that reported by Julio C. Armas-Pérez and Jacqueline Quintana-H., Phys. Rev. E 83, 051709 (2011). The main difference is the lack of chirality in the model proposed, although they share some characteristics like the geometrical polarity. Our model is called a lollipop model, because its shape is constructed by a rounded section attached to the end of a stick. Contrary to what happens in three dimensions where chiral nematogens produce interesting and complex phases such as blue phases, the lack of molecular chirality of our model generates a richer phase diagram compared to the chiral system. We show numerical and some geometrical evidences that the lack of laterality of the non chiral model seems to provide more routes of molecular self-assembly, producing triatic, a random cluster and possibly a tetratic phase behavior which were not presented in the previous work. We support our conclusions using results obtained from isobaric and isochoric Monte Carlo simulations. Properties as the n-fold order parameters such as the nematic, tetratic and triatic as well as their correlation functions were used to characterize the phases. We also provide the Fourier transform of equilibrium configurations to analyze the n-fold symmetry characteristic of each phase.

  4. Modelling charge transport of discotic liquid-crystalline triindoles: the role of peripheral substitution.

    Science.gov (United States)

    Volpi, Riccardo; Camilo, Ana Claudia Santos; Filho, Demetrio A da Silva; Navarrete, Juan T López; Gómez-Lor, Berta; Delgado, M Carmen Ruiz; Linares, Mathieu

    2017-09-13

    We have performed a multiscale approach to study the influence of peripheral substitution in the semiconducting properties of discotic liquid-crystalline triindoles. Charge carrier mobility as high as 1.4 cm 2 V -1 s -1 was experimentally reported for triindoles substituted with alkynyl chains on the periphery (Gómez-Lor et al. Angew. Chem., Int. Ed., 2011, 50, 7399-7402). In this work, our goal is to get a deeper understanding of both the molecular electronic structure and microscopic factors affecting the charge transport properties in triindoles as a function of the spacer group connecting the central cores with the external alkyl chains (i.e., alkyne or phenyl spacers groups). To this end, we first perform Quantum Mechanical (QM) calculations to assess how the peripheral substitution affects the electronic structure and the internal reorganization energy. Secondly, boxes of stacked molecules were built and relaxed through molecular dynamics to obtain realistic structures. Conformational analysis and calculations of transfer integrals for closed neighbours were performed. Our results show that the insertion of ethynyl spacers between the central aromatic core and the flexible peripheral chains results in lower reorganization energies and enhanced intermolecular order within the stacks with a preferred cofacial 60° staggered conformation, which would result in high charge-carrier mobilities in good agreement with the experimental data. This work allows a deeper understanding of charge carrier mobility in columnar phases, linking the structural order at the molecular level to the property of interest, i.e. the charge carrier mobility. We hope that this understanding will improve the design of systems at the supramolecular level aiming at obtaining a more defined conducting channel, higher mobility and smaller fluctuations within the column.

  5. Development and evaluation of exemestane-loaded lyotropic liquid crystalline gel formulations.

    Science.gov (United States)

    Musa, Muhammad Nuh; David, Sheba Rani; Zulkipli, Ihsan Nazurah; Mahadi, Abdul Hanif; Chakravarthi, Srikumar; Rajabalaya, Rajan

    2017-01-01

    Introduction: The use of liquid crystalline (LC) gel formulations for drug delivery has considerably improved the current delivery methods in terms of bioavailability and efficacy. The purpose of this study was to develop and evaluate LC gel formulations to deliver the anti-cancer drug exemestane through transdermal route. Methods: Two LC gel formulations were prepared by phase separation coacervation method using glyceryl monooleate (GMO), Tween 80 and Pluronic® F127 (F127). The formulations were characterized with regard to encapsulation efficiency (EE), vesicle size, Fourier transform infrared (FTIR) spectroscopy, surface morphology (using light and fluorescence microscopy), in vitro release, ex vivo permeation, in vitro effectiveness test on MDA-MB231 cancer cell lines and histopathological analysis. Results: Results exhibited that the EE was 85%-92%, vesicle size was 119.9-466.2 nm while morphology showed spherical vesicles after hydration. An FTIR result also revealed that there was no significant shift in peaks corresponding to Exemestane and excipients. LC formulations release the drug from cellulose acetate and Strat-MTM membrane from 15%-88.95%, whereas ex vivo permeation ranges from 37.09-63%. The in vitro effectiveness study indicated that even at low exemestane concentrations (12.5 and 25 μg/mL) the formulations were able to induce cancer cell death, regardless of the surfactant used. Histopathological analysis thinning of the epidermis as the formulations penetrate into the intercellular regions of squamous cells. Conclusion: The results conjectured that exemestane could be incorporated into LC gels for the transdermal delivery system and further preclinical studies such as pharmacokinetic and pharmacodynamic studies will be carried out with suitable animal models.

  6. Transient molecular orientation and rheology in flow aligning thermotropic liquid crystalline polymers

    International Nuclear Information System (INIS)

    Ugaz, Victor M.; Burghardt, Wesley R.; Zhou, Weijun; Kornfield, Julia A.

    2001-01-01

    Quantitative measurements of molecular orientation and rheology are reported for various transient shear flows of a nematic semiflexible copolyether. Unlike the case of lyotropic liquid crystalline polymers (LCPs), whose structure and rheology in shear are dominated by director tumbling, this material exhibits flow aligning behavior. The observed behavior is quite similar to that seen in a copolyester that we have recently studied [Ugaz and Burghardt (1998)], suggesting that flow aligning dynamics may predominate in main-chain thermotropes that incorporate significant chain flexibility. Since the flow aligning regime has received little attention in previous attempts to model the rheology of textured, polydomain LCPs, we attempt to determine whether available models are capable of predicting the orientation and stress response of this class of LCP. We first examine the predictions of the polydomain Ericksen model, an adaptation of Ericksen's transversely isotropic fluid model which accounts for the polydomain distribution of director orientation while neglecting distortional elasticity. This simple model captures a number of qualitative and quantitative features associated with the evolution of orientation and stress during shear flow inception, but cannot cope with reversing flows. To consider the possible role of distortional elasticity in the re-orientation dynamics upon reversal, we evaluate the mesoscopically averaged domain theory of Larson and Doi [Larson and Doi (1991)], which incorporates a phenomenological description of distortional elastic effects. To date, their approach to account for polydomain structure has only been applied to describe tumbling LCPs. We find that it captures the qualitative transient orientation response to flow reversals, but is less successful in describing the evolution of stresses. This is linked to the decoupling approximation adopted during the model's development. Finally, a modified polydomain Ericksen model is introduced

  7. Solvation Dynamics in Different Phases of the Lyotropic Liquid Crystalline System.

    Science.gov (United States)

    Roy, Bibhisan; Satpathi, Sagar; Gavvala, Krishna; Koninti, Raj Kumar; Hazra, Partha

    2015-09-03

    Reverse hexagonal (HII) liquid crystalline material based on glycerol monooleate (GMO) is considered as a potential carrier for drugs and other important biomolecules due to its thermotropic phase change and excellent morphology. In this work, the dynamics of encapsulated water, which plays important role in stabilization and formation of reverse hexagonal mesophase, has been investigated by time dependent Stokes shift method using Coumarin-343 as a solvation probe. The formation of the reverse hexagonal mesophase (HII) and transformation to the L2 phase have been monitored using small-angle X-ray scattering and polarized light microscopy experiments. REES studies suggest the existence of different polar regions in both HII and L2 systems. The solvation dynamics study inside the reverse hexagonal (HII) phase reveals the existence of two different types of water molecules exhibiting dynamics on a 120-900 ps time scale. The estimated diffusion coefficients of both types of water molecules obtained from the observed dynamics are in good agreement with the measured diffusion coefficient collected from the NMR study. The calculated activation energy is found to be 2.05 kcal/mol, which is associated with coupled rotational-translational water relaxation dynamics upon the transition from "bound" to "quasi-free" state. The observed ∼2 ns faster dynamics of the L2 phase compared to the HII phase may be associated with both the phase transformation as well as thermotropic effect on the relaxation process. Microviscosities calculated from time-resolved anisotropy studies infer that the interface is almost ∼22 times higher viscous than the central part of the cylinder. Overall, our results reveal the unique dynamical features of water inside the cylinder of reverse hexagonal and inverse micellar phases.

  8. Effect of doxorubicin on the order and dynamics of the acyl chains of anionic and zwitterionic phospholipids in liquid-crystalline mixed model membranes

    NARCIS (Netherlands)

    Wolf, de F.A.; Nicolaij, K.; Kruijff, de B.

    1992-01-01

    We investigated the effect of the antineoplastic drug doxorubicin on the order of the acyl chains in liquid-crystalline mixed bilayers consisting of dioleoylphosphatidylserine (DOPS) or -phosphatidic acid (DOPA), and dioleoylphosphatidylcholine (DOPC) or - hosphatidylethanolamine (DOPE). Previous

  9. The orientation-enhancing effect of diphenyl aluminium phosphate nanorods in a liquid-crystalline epoxy matrix ordered by magnetic field

    Czech Academy of Sciences Publication Activity Database

    Mossety-Leszczak, B.; Strachota, Beata; Strachota, Adam; Steinhart, Miloš; Šlouf, Miroslav

    2015-01-01

    Roč. 72, November (2015), s. 238-255 ISSN 0014-3057 Institutional support: RVO:61389013 Keywords : liquid-crystalline epoxy resins * magnetic field orientation * nanocomposites Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.485, year: 2015

  10. Solvent-free directed patterning of a highly ordered liquid crystalline organic semiconductor via template-assisted self-assembly for organic transistors.

    Science.gov (United States)

    Kim, Aryeon; Jang, Kwang-Suk; Kim, Jinsoo; Won, Jong Chan; Yi, Mi Hye; Kim, Hanim; Yoon, Dong Ki; Shin, Tae Joo; Lee, Myong-Hoon; Ka, Jae-Won; Kim, Yun Ho

    2013-11-20

    Highly ordered organic semiconductor micropatterns of the liquid-crystalline small molecule 2,7-didecylbenzothienobenzothiophene (C10 -BTBT) are fabricated using a simple method based on template-assisted self-assembly (TASA). The liquid crystallinity of C10 -BTBT allows solvent-free fabrication of high-performance printed organic field-effect transistors (OFETs). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. J-like liquid-crystalline and crystalline states of polyaniline revealed by thin, highly crystalline, and strongly oriented films

    Czech Academy of Sciences Publication Activity Database

    Gospodinova, Natalia; Tomšík, Elena; Omelchenko, Olga

    2014-01-01

    Roč. 118, č. 29 (2014), s. 8901-8904 ISSN 1520-6106 R&D Projects: GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : J-aggregates * organic semiconductors * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.302, year: 2014

  12. Magneto-responsive liquid crystalline elastomer nanocomposites as potential candidates for dynamic cell culture substrates

    International Nuclear Information System (INIS)

    Herrera-Posada, Stephany; Mora-Navarro, Camilo; Ortiz-Bermudez, Patricia; Torres-Lugo, Madeline; McElhinny, Kyle M.; Evans, Paul G.; Calcagno, Barbara O.; Acevedo, Aldo

    2016-01-01

    Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nanoparticles, and the evaluation of the effect of particle addition at low concentrations on the resultant structural, thermal, thermo-mechanical, and mechanical properties is presented. Phase transformations produced by heating in alternating magnetic fields were investigated in LCEs in contact with air, water, and a common liquid cell culture medium was also evaluated. The inclusion of nanoparticles into the elastomers displaced the nematic-to-isotropic phase transition, without affecting the nematic structure as evidenced by similar values of the order parameter, while reducing the maximum thermomechanical deformations. Remote and reversible deformations of the magnetic LCEs were achieved through the application of alternating magnetic fields, which induces the nematic–isotropic phase transition through nanoparticle heat generation. Formulation parameters can be modified to allow for remote actuation at values closer to the human physiological temperature range and within the range of deformations that can affect the cellular behavior of fibroblasts. Finally, a collagen surface treatment was performed to improve compatibility with NIH-3T3 fibroblast cultures, which enabled the attachment and proliferation of fibroblasts on substrates with and without magnetic particles under quiescent conditions. The LCEs developed in this work, which are able to deform and experience stress changes by remote contact-less magnetic stimulation, may allow for further studies on the effect of substrate morphology changes and dynamic mechanical properties during in vitro cell culture. - Highlights: • Magnetic LCE nanocomposites were

  13. Magneto-responsive liquid crystalline elastomer nanocomposites as potential candidates for dynamic cell culture substrates

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Posada, Stephany; Mora-Navarro, Camilo; Ortiz-Bermudez, Patricia; Torres-Lugo, Madeline [Department of Chemical Engineering, Call Box 9000, University of Puerto Rico, Mayagüez PR 00681 (Puerto Rico); McElhinny, Kyle M.; Evans, Paul G. [Department of Materials Science and Engineering, 1509 University Avenue, University of Wisconsin-Madison, WI 53706 (United States); Calcagno, Barbara O. [Department of General Engineering, Call Box 9000, University of Puerto Rico, Mayagüez PR 00681 (Puerto Rico); Acevedo, Aldo, E-mail: aldo.acevedo@upr.edu [Department of Chemical Engineering, Call Box 9000, University of Puerto Rico, Mayagüez PR 00681 (Puerto Rico)

    2016-08-01

    Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nanoparticles, and the evaluation of the effect of particle addition at low concentrations on the resultant structural, thermal, thermo-mechanical, and mechanical properties is presented. Phase transformations produced by heating in alternating magnetic fields were investigated in LCEs in contact with air, water, and a common liquid cell culture medium was also evaluated. The inclusion of nanoparticles into the elastomers displaced the nematic-to-isotropic phase transition, without affecting the nematic structure as evidenced by similar values of the order parameter, while reducing the maximum thermomechanical deformations. Remote and reversible deformations of the magnetic LCEs were achieved through the application of alternating magnetic fields, which induces the nematic–isotropic phase transition through nanoparticle heat generation. Formulation parameters can be modified to allow for remote actuation at values closer to the human physiological temperature range and within the range of deformations that can affect the cellular behavior of fibroblasts. Finally, a collagen surface treatment was performed to improve compatibility with NIH-3T3 fibroblast cultures, which enabled the attachment and proliferation of fibroblasts on substrates with and without magnetic particles under quiescent conditions. The LCEs developed in this work, which are able to deform and experience stress changes by remote contact-less magnetic stimulation, may allow for further studies on the effect of substrate morphology changes and dynamic mechanical properties during in vitro cell culture. - Highlights: • Magnetic LCE nanocomposites were

  14. Formulation and development of bicontinuous nanostructured liquid crystalline particles of efavirenz.

    Science.gov (United States)

    Avachat, Amelia M; Parpani, Shreekrishna S

    2015-02-01

    Efavirenz is a lipophilic non-nucleoside reverse transcriptase inhibitor used in the first-line pediatric therapeutic cocktail. Due to its high lipophilicity (logP = 5.4) and poor aqueous solubility (intrinsic water solubility = 8.3 μg/mL) efavirenz has low bioavailability. A 30 mg/mL solution in a medium-chain triglyceride vehicle is the only pediatric formulation available with an oral bioavailability 20% lower than the solid form. The current work was aimed at formulating and characterizing liquid crystal nanoparticles for oral delivery of efavirenz to improve oral bioavailability, provide sustained release, minimize side effects and drug resistance. Formulation of cubosomes was done by two methods; sonication and spray drying. Sonication gave highest entrapment efficiency and least particle size. Further, monoolein was substituted with phytantriol as monoolein gets degraded in the presence of lipase when administered orally with consequent loss of liquid crystalline structure. It was confirmed that there was no difference in particle size, entrapment efficiency and nature of product formed by using monoolein or phytantriol. The best formulation was found to be F9, having particle size 104.19 ± 0.21 nm and entrapment efficiency 91.40 ± 0.10%. In vitro release at the end of 12h was found to be 56.45% and zeta potential to be -23.14 mV which stabilized the cubic phase dispersions. It was further characterized for TEM, small angle X-ray scattering (SAXS), DSC and stability studies. SAXS revealed Pn3m space group, indicating a diamond cubic phase which was further confirmed by TEM. Pharmacokinetics of EFV was studied in male Wistar rats. EFV-loaded cubosome dispersions exhibited 1.93 and 1.62-fold increase in peak plasma concentration (Cmax) and 1.48 and 1.42-fold increase in AUC in comparison to that of a suspension prepared with the contents of EFV capsules suspended in 1.5% carboxymethylcellulose PBS solution (pH 5.0), and an EFV solution in medium

  15. Processing-microstructure relationships in thermotropic liquid crystalline polymers: Experimental and numerical modeling studies

    Science.gov (United States)

    Fang, Jun

    Thermotropic liquid crystalline polymers (TLCPs) are a class of promising engineering materials for high-demanding structural applications. Their excellent mechanical properties are highly correlated to the underlying molecular orientation states, which may be affected by complex flow fields during melt processing. Thus, understanding and eventually predicting how processing flows impact molecular orientation is a critical step towards rational design work in order to achieve favorable, balanced physical properties in finished products. This thesis aims to develop deeper understanding of orientation development in commercial TLCPs during processing by coordinating extensive experimental measurements with numerical computations. In situ measurements of orientation development of LCPs during processing are a focal point of this thesis. An x-ray capable injection molding apparatus is enhanced and utilized for time-resolved measurements of orientation development in multiple commercial TLCPs during injection molding. Ex situ wide angle x-ray scattering is also employed for more thorough characterization of molecular orientation distributions in molded plaques. Incompletely injection molded plaques ("short shots") are studied to gain further insights into the intermediate orientation states during mold filling. Finally, two surface orientation characterization techniques, near edge x-ray absorption fine structure (NEXAFS) and infrared attenuated total reflectance (FTIR-ATR) are combined to investigate the surface orientation distribution of injection molded plaques. Surface orientation states are found to be vastly different from their bulk counterparts due to different kinematics involved in mold filling. In general, complex distributions of orientation in molded plaques reflect the spatially varying competition between shear and extension during mold filling. To complement these experimental measurements, numerical calculations based on the Larson-Doi polydomain model

  16. Comparison of alignment tensors generated for native tRNAVal using magnetic fields and liquid crystalline media

    International Nuclear Information System (INIS)

    Latham, Michael P.; Hanson, Paul; Brown, Darin J.; Pardi, Arthur

    2008-01-01

    Residual dipolar couplings (RDCs) complement standard NOE distance and J-coupling torsion angle data to improve the local and global structure of biomolecules in solution. One powerful application of RDCs is for domain orientation studies, which are especially valuable for structural studies of nucleic acids, where the local structure of a double helix is readily modeled and the orientations of the helical domains can then be determined from RDC data. However, RDCs obtained from only one alignment media generally result in degenerate solutions for the orientation of multiple domains. In protein systems, different alignment media are typically used to eliminate this orientational degeneracy, where the combination of RDCs from two (or more) independent alignment tensors can be used to overcome this degeneracy. It is demonstrated here for native E. coli tRNA Val that many of the commonly used liquid crystalline alignment media result in very similar alignment tensors, which do not eliminate the 4-fold degeneracy for orienting the two helical domains in tRNA. The intrinsic magnetic susceptibility anisotropy (MSA) of the nucleobases in tRNA Val was also used to obtain RDCs for magnetic alignment at 800 and 900 MHz. While these RDCs yield a different alignment tensor, the specific orientation of this tensor combined with the high rhombicity for the tensors in the liquid crystalline media only eliminates two of the four degenerate orientations for tRNA Val . Simulations are used to show that, in optimal cases, the combination of RDCs obtained from liquid crystalline medium and MSA-induced alignment can be used to obtain a unique orientation for the two helical domains in tRNA Val

  17. THERMAL DEGRADATION OF THERMOTROPIC LIQUID CRYSTALLINE TERPOLYESTERS BASED ON VANILLIC ACID, p-HYDROXYBENZOIC ACID AND POLY(ETHYLENE TEREPHTHALATE)

    Institute of Scientific and Technical Information of China (English)

    LI Xingui; HUANG Meirong; GUAN Guihe; SUN Tong

    1993-01-01

    Nine thermotropic liquid crystalline terpolyesters based on vanillic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5~70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384~394 ℃ at a heating rate of 1 ℃/min and 176~205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.

  18. Smectic order and backbone anisotropy of a side-chain liquid crystalline polymer by Small-Angle Neutron Scattering

    Science.gov (United States)

    Noirez, L.; Pépy, G.; Keller, P.; Benguigui, L.

    1991-07-01

    We have simultaneously measured, for the first time, the extension of the polymer backbone of a side-chain liquid crystalline polymer and the intensity of the 001 Bragg reflection, which gives the smectic order parameter Psi as a function of temperature in the smectic phase. We have qualitatively demonstrated that the more the smectic phase is ordered, the more the polymer backbone is localized between the mesogenic layers. It is shown that the Landau theory allows us to relate the radius of gyration parallel to the magnetic field of the polymer backbone to the smectic order parameter. We also show that the Renz-Warner theory is suitable at low temperatures.

  19. Preparation and Characterization of Liquid Crystalline Polyurethane/Al2O3/Epoxy Resin Composites for Electronic Packaging

    Directory of Open Access Journals (Sweden)

    Shaorong Lu

    2012-01-01

    Full Text Available Liquid crystalline polyurethane (LCPU/Al2O3/epoxy resin composites were prepared by using LCPU as modifier. The mechanical properties, thermal stability, and electrical properties of the LCPU/Al2O3/epoxy resin composites were investigated systematically. The thermal oxidation analysis indicated that LCPU/Al2O3/epoxy resin composites can sustain higher thermal decomposition temperature. Meanwhile, coefficient of thermal expansion (CTE was also found to decrease with addition of LCPU and nano-Al2O3.

  20. Designing solution-processable air-stable liquid crystalline crosslinkable semiconductors

    DEFF Research Database (Denmark)

    McCulloch, I.; Bailey, C.; Genevicius, K.

    2006-01-01

    organic light emitting diode displays, low frequency radio frequency identification tag and other low performance electronics. Organic semiconductors that offer both electrical performance and stability with respect to storage and operation under ambient conditions are required. This work describes...... the development of reactive mesogen semiconductors, which form large crosslinked LC domains on polymerization within mesophases. These crosslinked domains offer mechanical stability and are inert to solvent exposure in further processing steps. Reactive mesogens containing conjugated aromatic cores, designed...

  1. 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.

  2. Small Angle Neutron Scattering Studies on Blends of Poly (Styrene-ran-Vinyl Phenol) with Liquid Crystalline Polyurethane

    Science.gov (United States)

    Mehta, Rujul

    2005-03-01

    Molecular composites, composed of uniformly dispersed rigid-rod liquid crystalline polymer (LCP) molecules in a flexible amorphous polymer matrix, have remained hitherto elusive due to a scarcity of miscible systems containing a LCP and an amorphous polymer. The production of such a blend, with an experimentally accessible miscibility window, has become possible by modifying the architecture of the flexible polymer, so as to induce favorable intermolecular hydrogen bonding. Specifically, liquid crystalline polyurethanes (LCPU) are found to be miscible with a copolymer of styrene and vinyl phenol; with optimum hydrogen bonding between the carbonyl groups of the urethane linkages and the hydroxyl groups present in the styrenic matrix. Availability of a truly miscible molecular composite presents a unique opportunity of studying the confirmation of polymer chains containing rigid-rods that are uniformly dispersed in a flexible coil matrix. A system consisting of the LCPU and the deuterated styrenic copolymer containing 20% vinyl phenol is examined by Small Angle Neutron Scattering at the National Center for Neutron Research at Gaithersburg and Technology, and the Institute of Solid State Research (IFF) at Jülich. Scattering curves for neat dPS-VPh did not fit the Debye-Bueche model; indicating complex structure. A two correlation length Debye-Bueche model was considered to accommodate for this nonlinear behavior. This model utilizes four fitting parameters, including two correlation lengths a1 and a2, corresponding to a Debye-Bueche model and Guinier model.

  3. Magnetic Field Alignment of PS-P4VP: a Non-Liquid Crystalline Coil-Coil Block Copolymer

    Science.gov (United States)

    Rokhlenko, Yekaterina; Zhang, Kai; Larson, Steven; Gopalan, Padma; O'Hern, Corey; Osuji, Chinedum

    2015-03-01

    Magnetic fields provide the ability to control alignment of self-assembled soft materials such as block copolymers. Most prior work in this area has relied on the presence of ordered assemblies of anisotropic liquid crystalline species to ensure sufficient magnetic anisotropy to drive alignment. Recent experiments with poly(styrene-b-4-vinylpyridine), a non-liquid crystalline BCP, however, show field-induced alignment of a lamellar microstructure during cooling across the order-disorder transition. Using in situ x-ray scattering, we examine the roles of field strength and cooling rate on the alignment response of this low MW coil-coil BCP. Alignment is first observed at field strengths as low as 1 Tesla and improves markedly with both increasing field strength and slower cooling. We present a geometric argument to illustrate the origin of a finite, non-trivial magnetic susceptibility anisotropy for highly stretched surface-tethered polymer chains and corroborate this using coarse-grained molecular dynamics simulations. We rationalize the magnetic field response of the system in terms of the mobility afforded by the absence of entanglements, the intrinsic anisotropy resulting from the stretched polymer chains and sterically constrained conjugated rings, and the large grain size in these low molecular weight materials.

  4. Induced liquid-crystalline ordering in solutions of stiff and flexible amphiphilic macromolecules: Effect of mixture composition

    International Nuclear Information System (INIS)

    Glagolev, Mikhail K.; Vasilevskaya, Valentina V.; Khokhlov, Alexei R.

    2016-01-01

    Impact of mixture composition on self-organization in concentrated solutions of stiff helical and flexible macromolecules was studied by means of molecular dynamics simulation. The macromolecules were composed of identical amphiphilic monomer units but a fraction f of macromolecules had stiff helical backbones and the remaining chains were flexible. In poor solvents the compacted flexible macromolecules coexist with bundles or filament clusters from few intertwined stiff helical macromolecules. The increase of relative content f of helical macromolecules leads to increase of the length of helical clusters, to alignment of clusters with each other, and then to liquid-crystalline-like ordering along a single direction. The formation of filament clusters causes segregation of helical and flexible macromolecules and the alignment of the filaments induces effective liquid-like ordering of flexible macromolecules. A visual analysis and calculation of order parameter relaying the anisotropy of diffraction allow concluding that transition from disordered to liquid-crystalline state proceeds sharply at relatively low content of stiff components.

  5. Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

    Directory of Open Access Journals (Sweden)

    B. Qi

    2014-07-01

    Full Text Available Graphene oxide (GO sheets were chemically grafted with thermotropic liquid crystalline epoxy (TLCP. Then we fabricated composites using TLCP-g-GO as reinforcing filler. The mechanical properties and thermal properties of composites were systematically investigated. It is found that the thermal and mechanical properties of the composites are enhanced effectively by the addition of fillers. For instance, the composites containing 1.0 wt% of TLCP-g-GO present impact strength of 51.43 kJ/m2, the tensile strength of composites increase from 55.43 to 80.85 MPa, the flexural modulus of the composites increase by more than 48%. Furthermore, the incorporation of fillers is effective to improve the glass transition temperature and thermal stability of the composites. Therefore, the presence of the TLCP-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.

  6. Entrapment of curcumin into monoolein-based liquid crystalline nanoparticle dispersion for enhancement of stability and anticancer activity

    Directory of Open Access Journals (Sweden)

    Baskaran R

    2014-06-01

    Full Text Available Rengarajan Baskaran,1 Thiagarajan Madheswaran,2 Pasupathi Sundaramoorthy,1 Hwan Mook Kim,1 Bong Kyu Yoo1 1College of Pharmacy, Gachon University, Incheon, South Korea; 2College of Pharmacy Yeungnam University, Gyeongsan, South Korea Abstract: Despite the promising anticancer potential of curcumin, its therapeutic application has been limited, owing to its poor solubility, bioavailability, and chemical fragility. Therefore, various formulation approaches have been attempted to address these problems. In this study, we entrapped curcumin into monoolein (MO-based liquid crystalline nanoparticles (LCNs and evaluated the physicochemical properties and anticancer activity of the LCN dispersion. The results revealed that particles in the curcumin-loaded LCN dispersion were discrete and monodispersed, and that the entrapment efficiency was almost 100%. The stability of curcumin in the dispersion was surprisingly enhanced (about 75% of the curcumin survived after 45 days of storage at 40°C, and the in vitro release of curcumin was sustained (10% or less over 15 days. Fluorescence-activated cell sorting (FACS analysis using a human colon cancer cell line (HCT116 exhibited 99.1% fluorescence gating for 5 µM curcumin-loaded LCN dispersion compared to 1.36% for the same concentration of the drug in dimethyl sulfoxide (DMSO, indicating markedly enhanced cellular uptake. Consistent with the enhanced cellular uptake of curcumin-loaded LCNs, anticancer activity and cell cycle studies demonstrated apoptosis induction when the cells were treated with the LCN dispersion; however, there was neither noticeable cell death nor significant changes in the cell cycle for the same concentration of the drug in DMSO. In conclusion, entrapping curcumin into MO-based LCNs may provide, in the future, a strategy for overcoming the hurdles associated with both the stability and cellular uptake issues of the drug in the treatment of various cancers. Keywords: liquid

  7. Self-assembled liquid crystalline nanoparticles as a novel ophthalmic delivery system for dexamethasone: Improving preocular retention and ocular bioavailability.

    Science.gov (United States)

    Gan, Li; Han, Shun; Shen, Jinqiu; Zhu, Jiabi; Zhu, Chunliu; Zhang, Xinxin; Gan, Yong

    2010-08-30

    The object of this study was to design novel self-assembled liquid crystalline nanoparticles (cubosomes) as an ophthalmic delivery system for dexamethasone (DEX) to improve its preocular retention and ocular bioavailability. DEX cubosome particles were produced by fragmenting a cubic crystalline phase of monoolein and water in the presence of stabilizer Poloxamer 407. Small angle X-ray diffraction (SAXR) profiles revealed its internal structure as Pn3m space group, indicating the diamond cubic phase. In vitro, the apparent permeability coefficient of DEX administered in cubosomes exhibited a 4.5-fold (F1) and 3.5-fold (F2) increase compared to that of Dex-Na phosphate eye drops. Preocular retention studies revealed that the retention of cubosomes was significantly longer than that of solution and carbopol gel, with AUC(0-->180min) of Rh B cubosomes being 2-3-fold higher than that of the other two formulations. In vivo pharmacokinetics in aqueous humor was evaluated by microdialysis, which indicated a 1.8-fold (F1) increase in AUC(0-->240min) of DEX administered in cubosomes relative to that of Dex-Na phosphate eye drops, with about an 8-fold increase compared to that of DEX suspension. Corneal cross-sections after incubation with DEX cubosomes demonstrated an unaffected corneal structure and tissue integrity, which indicated the good biocompatibility of DEX cubosomes. In conclusion, self-assembled liquid crystalline nanoparticles might represent a promising vehicle for effective ocular drug delivery. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

  8. Synthesis, liquid crystallinity, and chiroptical properties of sterol-containing polyacetylenes

    Science.gov (United States)

    Lam, Jacky Wing Yip; Lai, Lo Ming; Tang, Ben Zhong

    2006-08-01

    Poly(phenylacetylene)s and poly(1-alkyne)s containing chiral sterol pendant groups with molecular structures of -[HC=C-C 6H 4-CO II-R] n-, -[HC=C-C 6H 4-O(CH II) 10-CO II-R] n- and -[HC=C(CH II) mCO II-R] n-, (where R = cholesterol, stigmasterol, ergosterol and m = 2, 3, 8} are designed and synthesized. The monomers are prepared by esterifications of acetylenic acids with cholesterol, stigmasterol, and ergosterol and exhibit cholestericity at high temperatures. Polymerizations of the monomers are effected by WCl 6-Ph 4Sn, MoCl 5-Ph 4Sn, and organorhodium catalysts, giving high molecular weight (M w up to 8.0 × 10 5) polymers in high yields (up to 99%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, X-ray, UV, and CD analyses. All the polymers are thermally stable (greater than or equal to 300 °C). Polymers with long flexible alkyl chains form smectic and cholesteric phases at elevated temperatures. With an increase in the spacer length in poly(1-alkyne)s, the packing arrangements of the mesogenic pendants in the mesophases change from bilayer or mixed mono- and bilayer into homogeneous monolayer structures. Few poly(phenylacetylene)s show CD bands in the absorption region of the polyacetylene backbones, revealing that the main chains are helically rotating with a preferred screw sense.

  9. Atomic force and optical near-field microscopic investigations of polarization holographic gratings in a liquid crystalline azobenzene side-chain polyester

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Holme, N.C.R.; Hvilsted, S.

    1996-01-01

    Atomic force and scanning near-field optical microscopic investigations have been carried out on a polarization holographic grating recorded in an azobenzene side-chain Liquid crystalline polyester. It has been found that immediately following laser irradiation, a topographic surface grating...

  10. 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.

  11. PEGylation of Phytantriol-Based Lyotropic Liquid Crystalline Particles-The Effect of Lipid Composition, PEG Chain Length, and Temperature on the Internal Nanostructure

    DEFF Research Database (Denmark)

    Nilsson, Christa; Ostergaard, Jesper; Larsen, Susan Weng

    2014-01-01

    of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based...

  12. 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

  13. Polyamine structural effects on the induction and stabilization of liquid crystalline DNA: potential applications to DNA packaging, gene therapy and polyamine therapeutics.

    Science.gov (United States)

    Saminathan, M; Thomas, Thresia; Shirahata, Akira; Pillai, C K S; Thomas, T J

    2002-09-01

    DNA undergoes condensation, conformational transitions, aggregation and resolubilization in the presence of polyamines, positively charged organic molecules present in all cells. Under carefully controlled environmental conditions, DNA can also transform to a liquid crystalline state in vitro. We undertook the present work to examine the ability of spermidine, N4-methylspermidine, spermine, N1-acetylspermine and a group of tetramine, pentamine and hexamine analogs of spermine to induce and stabilize liquid crystalline DNA. Liquid crystalline textures were identified under a polarizing microscope. In the absence of polyamines, calf thymus DNA assumed a diffused, planar cholesteric phase with entrapped bubbles when incubated on a glass slide at 37 degrees C. In the presence of spermidine and spermine, the characteristic fingerprint textures of the cholesteric phase, adopting a hexagonal order, were obtained. The helical pitch was 2.5 micro m. The final structures were dendrimeric and crystalline when DNA was treated with spermine homologs and bis(ethyl) derivatives. A cholesteric structure was observed when DNA was treated with a hexamine at 37 degrees C. This structure changed to a hexagonal dendrimer with fluidity on prolonged incubation. These data show a structural specificity effect of polyamines on liquid crystalline phase transitions of DNA and suggest a possible physiological function of natural polyamines.

  14. Phospholipids chiral at phosphorus. Dramatic effects of phosphorus chirality on the deuterium NMR properties of the choline head group of phospholipids in the liquid crystalline phase

    International Nuclear Information System (INIS)

    Loffredo, W.M.; Jiang, Rutai; Tsai, Mingdaw

    1990-01-01

    To probe the motional and conformational propertis of the choline head group of 1,2-dipalmitoyl-sn-glycero-3-thiophosphocholine (DPPsC), the R p , S p , and R p + S p isomers of [α-D 2 ]DPPsC, [β-D 2 ]DPPsC, and [δ-D 9 ]DPPsC in the subgel, gel, and liquid crystalline phases were investigated with deuterium NMR, and the results were compared with those of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) labeled at the same positions. In the subgel phase (5 degree C) all isomers of [α-D 2 ]DPPsC and [β-D 2 ]DPPsC displayed amorphous line shapes characteristic of a restricted and disordered motional environment, whereas [δ-D 9 ]DPPsC showed narrower and symmetric line shapes indicating substantial motions. For all three labeled positions the apparent line width of the R p isomer is larger than those of S p and R p + S p isomers, and the amorphous line shape of the R p isomer also persists at 25 and 35 degree C. These results indicate that the motional and conformational properties of the C α -C β segment of DPPsC is very sensitive to the configuration at phosphorus. Structurally, this provides strong support for noncovalent interactions between the quaternary ammonium group of choline and the phosphate group of a neighboring molecule in the bilayers of phosphatidylcholine and suggests that such interactions are important to the motion of the choline chain

  15. Ericksen number and Deborah number cascade predictions of a model for liquid crystalline polymers for simple shear flow

    Science.gov (United States)

    Klein, D. Harley; Leal, L. Gary; García-Cervera, Carlos J.; Ceniceros, Hector D.

    2007-02-01

    We consider the behavior of the Doi-Marrucci-Greco (DMG) model for nematic liquid crystalline polymers in planar shear flow. We found the DMG model to exhibit dynamics in both qualitative and quantitative agreement with experimental observations reported by Larson and Mead [Liq. Cryst. 15, 151 (1993)] for the Ericksen number and Deborah number cascades. For increasing shear rates within the Ericksen number cascade, the DMG model displays three distinct regimes: stable simple shear, stable roll cells, and irregular structure accompanied by disclination formation. In accordance with experimental observations, the model predicts both ±1 and ±1/2 disclinations. Although ±1 defects form via the ridge-splitting mechanism first identified by Feng, Tao, and Leal [J. Fluid Mech. 449, 179 (2001)], a new mechanism is identified for the formation of ±1/2 defects. Within the Deborah number cascade, with increasing Deborah number, the DMG model exhibits a streamwise banded texture, in the absence of disclinations and roll cells, followed by a monodomain wherein the mean orientation lies within the shear plane throughout the domain.

  16. Electrostatic Effects in Phase Transitions of Biomembranes between Cubic Phases and Lamellar Liquid-Crystalline (Lα) phase

    Science.gov (United States)

    Masum, Shah Md.; Li, Shu Jie; Tamba, Yukihiro; Yamashita, Yuko; Yamazaki, Masahito

    2004-04-01

    Elucidation of the mechanisms of transitions between cubic phase and liquid-crystalline (Lα) phase, and between different IPMS cubic phases, are essential for understanding of dynamics of biomembranes and topological transformation of lipid membranes. Recently, we found that electrostatic interactions due to surface charges of lipid membranes induce transition between cubic phase and Lα phase, and between different IPMS cubic phases. As electrostatic interactions increase, the most stable phase of a monoolein (MO) membrane changes: Q224 ⇒ Q229 ⇒ Lα. We also found that a de novo designed peptide partitioning into electrically neutral lipid membrane changed the phase stability of the MO membranes. As peptide-1 concentration increased, the most stable phase of a MO membrane changes: Q224 ⇒ Q229 ⇒Lα. In both cases, the increase in the electrostatic repulsive interaction greatly reduced the absolute value of spontaneous curvature of the MO monolayer membrane. We also investigated factors such as poly (L-lysine) and osmotic stress to control structure and phase stability of DOPA/MO membranes. Based on these results, we discuss the mechanism of the effect of electrostatic interactions on the stability of cubic phase.

  17. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    International Nuclear Information System (INIS)

    Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G.

    2014-01-01

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  18. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    Science.gov (United States)

    Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G.

    2014-10-01

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4-5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  19. Selectively deuterated liquid crystalline cyanoazobenzene side-chain polyesters. 3. Investigations of laser induced segmental mobility by Fourier transform infrared spectroscopy

    DEFF Research Database (Denmark)

    Kulinna, Christian; Hvilsted, Søren; Hendann, Claudia

    1998-01-01

    The laser-induced anisotropy in thin films of an extensive number of cyanoazobenzene sidechain liquid crystalline polytetradecanedioates, -dodecanedioates, and -adipates selectively deuterated at different positions have been investigated with polarized FTIR spectroscopy. The analysis of the segm......The laser-induced anisotropy in thin films of an extensive number of cyanoazobenzene sidechain liquid crystalline polytetradecanedioates, -dodecanedioates, and -adipates selectively deuterated at different positions have been investigated with polarized FTIR spectroscopy. The analysis...... of the segmental orientation based on dichroic ratios of characteristic absorption bands shows that, in polyesters with long main-chain spacing (tetradecanedioates and dodecanedioates), not only the light sensitive azo chromophore but also the main-chain methylene segment and to a smaller extent the flexible...

  20. 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.

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

    International Nuclear Information System (INIS)

    Tylkowski, Bartosz; Castelao, Nuria; Giamberini, Marta; Garcia-Valls, Ricard; Reina, José Antonio; Gumí, Tània

    2012-01-01

    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® 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: ► We prepared oriented membranes based on a liquid crystalline columnar polyether. ► In this structure, the inner polyether chain could work as an ion channel. ► We obtained membranes by casting a chloroform solution in the presence of water. ► Membranes showed good proton permeability due to the presence of oriented channels.

  2. Entrapment of curcumin into monoolein-based liquid crystalline nanoparticle dispersion for enhancement of stability and anticancer activity

    Science.gov (United States)

    Baskaran, Rengarajan; Madheswaran, Thiagarajan; Sundaramoorthy, Pasupathi; Kim, Hwan Mook; Yoo, Bong Kyu

    2014-01-01

    Despite the promising anticancer potential of curcumin, its therapeutic application has been limited, owing to its poor solubility, bioavailability, and chemical fragility. Therefore, various formulation approaches have been attempted to address these problems. In this study, we entrapped curcumin into monoolein (MO)-based liquid crystalline nanoparticles (LCNs) and evaluated the physicochemical properties and anticancer activity of the LCN dispersion. The results revealed that particles in the curcumin-loaded LCN dispersion were discrete and monodispersed, and that the entrapment efficiency was almost 100%. The stability of curcumin in the dispersion was surprisingly enhanced (about 75% of the curcumin survived after 45 days of storage at 40°C), and the in vitro release of curcumin was sustained (10% or less over 15 days). Fluorescence-activated cell sorting (FACS) analysis using a human colon cancer cell line (HCT116) exhibited 99.1% fluorescence gating for 5 μM curcumin-loaded LCN dispersion compared to 1.36% for the same concentration of the drug in dimethyl sulfoxide (DMSO), indicating markedly enhanced cellular uptake. Consistent with the enhanced cellular uptake of curcumin-loaded LCNs, anticancer activity and cell cycle studies demonstrated apoptosis induction when the cells were treated with the LCN dispersion; however, there was neither noticeable cell death nor significant changes in the cell cycle for the same concentration of the drug in DMSO. In conclusion, entrapping curcumin into MO-based LCNs may provide, in the future, a strategy for overcoming the hurdles associated with both the stability and cellular uptake issues of the drug in the treatment of various cancers. PMID:25061290

  3. Glyceryl monooleyl ether-based liquid crystalline nanoparticles as a transdermal delivery system of flurbiprofen: characterization and in vitro transport.

    Science.gov (United States)

    Uchino, Tomonobu; Murata, Akiko; Miyazaki, Yasunori; Oka, Toshihiko; Kagawa, Yoshiyuki

    2015-01-01

    Liquid crystalline nanoparticles (LCNs) were prepared using glyceryl monooleyl ether (GME) by the modified film rehydration method. Hydrogenated lecithin (HL), 1,3-butylene glycol (1,3-BG), and Poloxamer 407 were used as additives. The prepared LCN formulations were evaluated based on particle size, small-angle X-ray diffraction (SAXS) analysis, (1)H- and (19)F-NMR spectra, and in vitro skin permeation across Yucatan micropig skin. The composition (weight percent) of the LCN formulations were GME-HL-1,3-BG (4 : 1 : 15), 4% GME-based LCN and GME-HL-1,3-BG (8 : 1 : 15), 8% GME-based LCN and their mean particle sizes were 130-175 nm. Flurbiprofen 5 and 10 mg was loaded into 4% GME-based LCN and 8% GME-based LCN systems, respectively. The results of SAXS and NMR suggested that both flurbiprofen-loaded formulations consist of particles with reverse type hexagonal phase (formation of hexosome) and flurbiprofen molecules were localized in the lipid domain through interaction of flurbiprofen with the lipid components. Flurbiprofen transport from the LCN systems across the Yucatan micropig skin was increased compared to flurbiprofen in citric buffer (pH=3.0). The 8% GME-based LCN systems was superior to the 4% GME-based LCN for flurbiprofen transport. Since the internal hexagonal phase in the 8% GME-based LCN systems had a higher degree of order compared to the 4% GME-based LCN in SAXS patterns, the 8% GME-based LCN system had a larger surface area, which might influence flurbiprofen permeation. These results indicated that the GME-based LCN system is effective in improving the skin permeation of flurbiprofen across the skin.

  4. Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction.

    Science.gov (United States)

    Saed, Mohand O; Torbati, Amir H; Nair, Devatha P; Yakacki, Christopher M

    2016-01-19

    This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

  5. Liquid Crystalline Symposium

    National Research Council Canada - National Science Library

    Mather, Patrick

    2003-01-01

    .... Talks spanned a very diverse set of LC-related topics, ranging from reports on the latest hot research areas, including flexoelectrooptics, V-shaped switching, chiral discotics, and banana phases...

  6. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation

    Science.gov (United States)

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-05-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the amount of glyceryl monoolein, and the ratio of poloxamer 407 to glyceryl monoolein were selected as the factors that were used to optimize the dependent variables, which included encapsulation efficiency and drug loading. A three-factor, five-level central composite design was constructed to optimize the formulation. TET-loaded LCNPs (TET-LCNPs) were characterized to determine their particle size, zeta potential, entrapment efficiency, drug loading capacity, particle morphology, inner crystalline structure, and in vitro drug release profile. Corneal permeation in excised rabbit corneas was evaluated. Pre-ocular retention was determined using a noninvasive fluorescence imaging system. Finally, pharmacokinetic study in the aqueous humor was performed by microdialysis technique. The optimal formulation had a mean particle size of 170.0 ± 13.34 nm, a homogeneous distribution with polydispersity index of 0.166 ± 0.02, a positive surface charge with a zeta potential of 29.3 ± 1.25 mV, a high entrapment efficiency of 95.46 ± 4.13 %, and a drug loading rate of 1.63 ± 0.07 %. Transmission electron microscopy showed spherical particles that had smooth surfaces. Small-angle X-ray scattering profiles revealed an inverted hexagonal phase. The in vitro release assays showed a sustained drug release profile. A corneal permeation study showed that the apparent permeability coefficient of the optimal formulation was 2.03-fold higher than that of the TET solution. Pre-ocular retention

  7. Development and characterization of p1025-loaded bioadhesive liquid-crystalline system for the prevention of Streptococcus mutans biofilms.

    Science.gov (United States)

    Calixto, Giovana Maria Fioramonti; Duque, Cristiane; Aida, Kelly Limi; Dos Santos, Vanessa Rodrigues; Massunari, Loiane; Chorilli, Marlus

    2018-01-01

    Formation of a dental biofilm by Streptococcus mutans can cause dental caries, and remains a costly health problem worldwide. Recently, there has been a growing interest in the use of peptidic drugs, such as peptide p1025, analogous to the fragments 1025-1044 of S. mutans cellular adhesin, responsible for the adhesion and formation of dental biofilm. However, peptides have physicochemical characteristics that may affect their biological action, limiting their clinical performance. Therefore, drug-delivery systems, such as a bioadhesive liquid-crystalline system (LCS), may be attractive strategies for peptide delivery. Potentiation of the action of LCS can be achieved with the use of bioadhesive polymers to prolong their residence on the teeth. In line with this, three formulations - polyoxypropylene-(5)-polyoxyethylene-(20)-cetyl alcohol, oleic acid, and Carbopol C974P in different combinations (F1C, F2C, and F3C) were developed to observe the influence of water in the LCS, with the aim of achieving in situ gelling in the oral environment. These formulations were assessed by polarized light microscopy, small-angle X-ray scattering, rheological analysis, and in vitro bioadhesion analysis. Then, p1025 and a control (chlorhexidine) were incorporated into the aqueous phase of the formulation (F + p1025 and F + chlorhexidine), to determine their antibiofilm effect and toxicity on epithelial cells. Polarized light microscopy and small-angle X-ray scattering showed that F1C and F2C were LCS, whereas F3C was a microemulsion. F1C and F2C showed pseudoplastic behavior and F3C Newtonian behavior. F1C showed the highest elastic and bioadhesive characteristics compared to other formulations. Antibiofilm effects were observed for F + p1025 when applied in the surface-bound salivary phase. The p1025-loaded nanostructured LCS presented limited cytotoxicity and effectively reduced S. mutans biofilm formation, and could be a promising p1025-delivery strategy to prevent the formation

  8. Development and characterization of p1025-loaded bioadhesive liquid-crystalline system for the prevention of Streptococcus mutans biofilms

    Directory of Open Access Journals (Sweden)

    Calixto GMF

    2017-12-01

    Full Text Available Giovana Maria Fioramonti Calixto,1 Cristiane Duque,2 Kelly Limi Aida,2 Vanessa Rodrigues dos Santos,2 Loiane Massunari,2 Marlus Chorilli1 1School of Pharmaceutical Sciences, São Paulo State University (UNESP, Araraquara, Brazil; 2School of Dentistry, São Paulo State University (UNESP, Araçatuba, Brazil Abstract: Formation of a dental biofilm by Streptococcus mutans can cause dental caries, and remains a costly health problem worldwide. Recently, there has been a growing interest in the use of peptidic drugs, such as peptide p1025, analogous to the fragments 1025–1044 of S. mutans cellular adhesin, responsible for the adhesion and formation of dental biofilm. However, peptides have physicochemical characteristics that may affect their biological action, limiting their clinical performance. Therefore, drug-delivery systems, such as a bioadhesive liquid-crystalline system (LCS, may be attractive strategies for peptide delivery. Potentiation of the action of LCS can be achieved with the use of bioadhesive polymers to prolong their residence on the teeth. In line with this, three formulations – polyoxypropylene-(5-polyoxyethylene-(20-cetyl alcohol, oleic acid, and Carbopol C974P in different combinations (F1C, F2C, and F3C were developed to observe the influence of water in the LCS, with the aim of achieving in situ gelling in the oral environment. These formulations were assessed by polarized light microscopy, small-angle X-ray scattering, rheological analysis, and in vitro bioadhesion analysis. Then, p1025 and a control (chlorhexidine were incorporated into the aqueous phase of the formulation (F + p1025 and F + chlorhexidine, to determine their antibiofilm effect and toxicity on epithelial cells. Polarized light microscopy and small-angle X-ray scattering showed that F1C and F2C were LCS, whereas F3C was a microemulsion. F1C and F2C showed pseudoplastic behavior and F3C Newtonian behavior. F1C showed the highest elastic and bioadhesive

  9. Effect of expanded graphite and PEI-co-Silicon Rubber on the thermo mechanical, morphological as well as rheological properties of in situ composites based on poly (ether imide) and liquid crystalline polymer

    Energy Technology Data Exchange (ETDEWEB)

    Hatui, Goutam, E-mail: hatui.goutam@gmail.com; Malas, Asish, E-mail: malasasish@gmail.com; Bhattacharya, Pallab; Dhibar, Saptarshi, E-mail: saptaaus2007@gmail.com; Kundu, Mrinal Kanti, E-mail: kanti.mrinal19@gmail.com; Kumar Das, Chapal, E-mail: chapal12@yahoo.co.in

    2015-01-15

    Highlights: • PEI/LCP/ PEI-co-Silicon Rubber/EG and PEI/LCP/MWCNT nano composites are prepared by melt blending method. • The dispersions of acid modified expanded graphite were improved in presence of PEI-co-Silicon Rubber. • Thermal stability was found to be highest for PLGC composite. • Storage modulus and Young’s modulus showed an upward trend with incorporation of only EG and EG in presence of PEI-co-Silicon Rubber. • Among the nano composites PLGC has highest viscosity. - Abstract: Nanocomposites of polyether imide (PEI) and liquid crystalline polymer (LCP) with either MWCNT, Expanded Graphite (EG) or in combination of both EG and PEI-co-Silicon Rubber were prepared by melt blending process. The compatibility between the polymeric phases (PEI and LCP) was observed to be increased by the addition of PEI-co-Silicon Rubber while the only MWCNT added system (PLC) resulted in smaller LCP droplets. A continuous morphology was produced in presence of both PEI-co-Silicon Rubber and EG both added system (PLGR). This was due to the compatibilizing effect of PEI-co-Silicon Rubber. FTIR analysis revealed interaction between PEI and LCP in presence of PEI-co-Silicon Rubber. Remarkable increment of storage modulus was observed with the addition of EG and PEI-co-Silicon Rubber. Transmission Electron Microscope (TEM) analysis showed better dispersion of multiple graphene layers of EG in presence of PEI-co-Silicon Rubber compatibilized system. Tensile and Young’s modulus both were highest for EG/ PEI-co-Silicon Rubber added system. This is due to flexible compatibilizing effect of PEI-co-Silicon Rubber which delayed the detachment of LCP domain from the PEI matrix and thus detains the fracture.

  10. Effect of expanded graphite and PEI-co-Silicon Rubber on the thermo mechanical, morphological as well as rheological properties of in situ composites based on poly (ether imide) and liquid crystalline polymer

    International Nuclear Information System (INIS)

    Hatui, Goutam; Malas, Asish; Bhattacharya, Pallab; Dhibar, Saptarshi; Kundu, Mrinal Kanti; Kumar Das, Chapal

    2015-01-01

    Highlights: • PEI/LCP/ PEI-co-Silicon Rubber/EG and PEI/LCP/MWCNT nano composites are prepared by melt blending method. • The dispersions of acid modified expanded graphite were improved in presence of PEI-co-Silicon Rubber. • Thermal stability was found to be highest for PLGC composite. • Storage modulus and Young’s modulus showed an upward trend with incorporation of only EG and EG in presence of PEI-co-Silicon Rubber. • Among the nano composites PLGC has highest viscosity. - Abstract: Nanocomposites of polyether imide (PEI) and liquid crystalline polymer (LCP) with either MWCNT, Expanded Graphite (EG) or in combination of both EG and PEI-co-Silicon Rubber were prepared by melt blending process. The compatibility between the polymeric phases (PEI and LCP) was observed to be increased by the addition of PEI-co-Silicon Rubber while the only MWCNT added system (PLC) resulted in smaller LCP droplets. A continuous morphology was produced in presence of both PEI-co-Silicon Rubber and EG both added system (PLGR). This was due to the compatibilizing effect of PEI-co-Silicon Rubber. FTIR analysis revealed interaction between PEI and LCP in presence of PEI-co-Silicon Rubber. Remarkable increment of storage modulus was observed with the addition of EG and PEI-co-Silicon Rubber. Transmission Electron Microscope (TEM) analysis showed better dispersion of multiple graphene layers of EG in presence of PEI-co-Silicon Rubber compatibilized system. Tensile and Young’s modulus both were highest for EG/ PEI-co-Silicon Rubber added system. This is due to flexible compatibilizing effect of PEI-co-Silicon Rubber which delayed the detachment of LCP domain from the PEI matrix and thus detains the fracture

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

    Science.gov (United States)

    Tetzner, Kornelius; Bose, Indranil R.; Bock, Karlheinz

    2014-01-01

    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. PMID:28788243

  12. 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.

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

    Science.gov (United States)

    Tetzner, Kornelius; Bose, Indranil R; Bock, Karlheinz

    2014-10-29

    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.

  14. Improving the thermal stability and electrical parameters of a liquid crystalline material 4-n-(nonyloxy) benzoic acid by using Li ion beam irradiation

    Science.gov (United States)

    Kumar, Satendra; Verma, Rohit; Dwivedi, Aanchal; Dhar, R.; Tripathi, Ambuj

    2018-05-01

    Li ion beam irradiation studies on a liquid crystalline material 4-n-(nonyloxy) benzoic acid (NOBA) have been carried out. The material has phase sequence of I-N-SmC-Cr. Thermodynamic studies demonstrate that an irradiation fluence of 1×1013 ions-cm-2 results in the increased thermal stability of the smectic C (SmC) phase of the material. Dielectric measurements illustrate that the transverse component of the dielectric permittivity and hence the dielectric anisotropy of the material in the nematic (N) and SmC phases are increased as compared to those of the pure material due to irradiation. UV-Visible spectrum of the irradiated material shows an additional peak along with the peak of the pure material. The observed change in the thermodynamic and electrical parameters is attributed to the conversion of some of the dimers of NOBA to monomers of NOBA due to irradiation.

  15. Semiflexible polymers confined in a slit pore with attractive walls: two-dimensional liquid crystalline order versus capillary nematization.

    Science.gov (United States)

    Milchev, Andrey; Egorov, Sergei A; Binder, Kurt

    2017-03-01

    Semiflexible polymers under good solvent conditions interacting with attractive planar surfaces are investigated by Molecular Dynamics (MD) simulations and classical Density Functional Theory (DFT). A bead-spring type potential complemented by a bending potential is used, allowing variation of chain stiffness from completely flexible coils to rod-like polymers whose persistence length by far exceeds their contour length. Solvent is only implicitly included, monomer-monomer interactions being purely repulsive, while two types of attractive wall-monomer interactions are considered: (i) a strongly attractive Mie-type potential, appropriate for a strictly structureless wall, and (ii) a corrugated wall formed by Lennard-Jones particles arranged on a square lattice. It is found that in dilute solutions the former case leads to the formation of a strongly adsorbed surface layer, and the profile of density and orientational order in the z-direction perpendicular to the wall is predicted by DFT in nice agreement with MD. While for very low bulk densities a Kosterlitz-Thouless type transition from the isotropic phase to a phase with power-law decay of nematic correlations is suggested to occur in the strongly adsorbed layer, for larger densities a smectic-C phase in the surface layer is detected. No "capillary nematization" effect at higher bulk densities is found in this system, unlike systems with repulsive walls. This finding is attributed to the reduction of the bulk density (in the center of the slit pore) due to polymer adsorption on the attractive wall, for a system studied in the canonical ensemble. Consequently in a system with two attractive walls nematic order in the slit pore can occur only at a higher density than for a bulk system.

  16. Effects of counterion valency on the damping of phonons propagating along the axial direction of liquid-crystalline DNA

    Science.gov (United States)

    Liu, Yun; Chen, Sow-Hsin; Berti, Debora; Baglioni, Piero; Alatas, Ahmet; Sinn, Harald; Alp, Ercan; Said, Ayman

    2005-12-01

    The phonon propagation and damping along the axial direction of films of aligned 40wt% calf-thymus DNA rods are studied by inelastic x-ray scattering (IXS). The IXS spectra are analyzed with the generalized three effective eigenmode theory, from which we extract the dynamic structure factor S (Q,E) as a function of transferred energy E =ℏω, and the magnitude of the transferred wave vector Q. S (Q,E) of a DNA sample typically consists of three peaks, one central Rayleigh scattering peak, and two symmetric Stokes and anti-Stokes Brillouin side peaks. By analyzing the Brillouin peaks, the phonon excitation energy and damping can be extracted at different Q values from about 4 to 30nm-1. A high-frequency sound speed is obtained from the initial slope of the linear portion of the dispersion relation below Q =4nm-1. The high-frequency sound speed obtained in this Q range is 3100m /s, which is about twice faster than the ultrasound speed of 1800m/s, measured by Brillouin light scattering at Q ˜0.01nm-1 at the similar hydration level. Our observations provide further evidence of the strong coupling between the internal dynamics of a DNA molecule and the dynamics of the solvent. The effect on damping and propagation of phonons along the axial direction of DNA rods due to divalent and trivalent counterions has been studied. It is found that the added multivalent counterions introduce stronger phonon damping. The phonons at the range between ˜12.5 and ˜22.5nm-1 are overdamped by the added counterions according to our model analyses. The intermediate scattering function is extracted and it shows a clear two-step relaxation with the fast relaxation time ranging from 0.1 to 4ps.

  17. Di-, tri-, tetranuclear clusters and polymeric cadmium compounds: Syntheses, structures and fluorescent properties with various linking fashions and high stability of orotates under the condition of strong bases

    International Nuclear Information System (INIS)

    Li Xing; Bing Yue; Zha Meiqin; Wang Dongjie; Han Lei; Cao Rong

    2011-01-01

    Assembly reactions of orotic acid (H 3 dtpc ) and CdCl 2 .2.5H 2 O or CdSO 4 .8H 2 O yielded four new cadmium compounds {[Cd(H 2 dtpc)(phen)(H 2 O) 2 ].(H 2 dtpc).4H 2 O} 2 (1: solution reaction, pH=4-5, in addition of phen), [Cd 3 (dtpc) 2 (phen) 5 ].13H 2 O (2: hydrothermal reaction, initial pH=14, final pH=7.5), [Cd(Hdtpc)(H 2 O) 3 ] 4 (3: solution reaction, initial pH=6.5, final pH=6.0), {[Cd(Hdtpc)(phen)(H 2 O)].H 2 O} n (4: hydrothermal reaction, initial pH=8; final pH=6.5), respectively. Compounds 1-4 have been characterized by IR, thermogravimetric analyses (TGA), photoluminescence analyses, single-crystal and powder X-ray diffraction (PXRD). Compound 1 is a binuclear, 2 is a trinuclear, 3 is a tetranuclear structure, and 4 possesses one-dimensional chain framework, respectively, in which the orotate ligands show seven different linking fashions in 1-4. The orotate ligands as trivalence anions are observed in the formation of orotate-compounds, in which the orotates show high stability under the extreme condition of strong basic solution, high temperature and pressure. - Graphical abstract: Assembly of orotic acid and Cd(II) salts result in four new compounds under different reaction conditions, the compounds possess strong photoluminescence emissions and high thermal stability. Highlights: → Four Cd-compounds were prepared from orotic acid under different crystallization systems. → The orotates as trivalence anions displayed high stability under extremely conditions. → The orotates displayed various connection modes in the compounds. → The strong photoluminescence emissions have been observed in the compounds.

  18. Synthesis and Characterization of Liquid Crystalline Copolymethacrylates, Copolyacrylates and Copolysiloxanes Containing 4-Methoxy-4’-Hydroxy-alpha-Methylstilbene and 4-Hydroxy-4’-Methoxy-alpha-Methylstilbene Constitutional Isomers as Side Groups.

    Science.gov (United States)

    1987-01-01

    10*C, concentrated sulfuric acid (31.0 g, 0.32 mole ) was added dropwise during 1.5 hr. The reaction mixture was stirred at this temperature for 2...characterization of the polymethacrylates . Indifferent of the thermal history and - ., .. _%,, n -x,, ; *> ;.. ’ . ,..... *p.****, * . - _. .. ... .~ • ’ -18...followed by a liquid crystalline mesophase, and the isotropization transition. Only the polymethacrylate containing eleven methylenic units in the

  19. Functional disubstituted polyacetylenes: Synthesis, liquid crystallinity, light emission, and fluorescent photopatterning of biphenyl-containing poly(1-phenyl-octyne)s with different functional bridges.

    Science.gov (United States)

    Lam, Jacky W Y; Qin, Anjun; Dong, Yuping; Lai, Lo Ming; Häussler, Matthias; Dong, Yongqiang; Tang, Ben Zhong

    2006-11-02

    Biphenyl (Biph)-containing 1-phenyl-1-octynes and their polymers are synthesized, and the effects of functional bridge groups on the mesomorphic and optical properties of the polymers are studied. The nonmesomorphic disubstituted acetylene monomers (C6H13)C[triple bond]C(C6H4)O(CH2)12O-Biph-OC7H15 (1), (C6H13)C[triple bond]C(C6H4)O(CH2)11OOC-Biph-OC7H15 (2), and (C6H13)C[triple bond]C(C6H4)CO2(CH2)12OOC-Biph-OC7H15 (3) are prepared by multistep reaction routes and converted into their corresponding polymers P1-P3 by a WCl6-Ph4Sn catalyst. The structures and properties of the polymers are characterized and evaluated by NMR, TGA, DSC, POM, XRD, UV, and PL analyses. The mesogenic pendants have endowed the polymers with high thermal stability (> or =400 degrees C). While P1 exhibits no liquid crystallinity, P2 and P3 form enantiotropic S(A) phase with a monolayer structure. Upon photoexcitation, the polymers emit blue and blue-green lights of 460 and 480 nm, respectively, in THF with quantum efficiencies larger than 30%. UV irradiation of a thin film of P2 through a mask oxidizes and quenches the light emission of the exposed regions, generating a two-dimensional luminescent photoimage.

  20. Liquid-crystalline dendrimer Cu(II) complexes and Cu(0) nanoclusters based on the Cu(II) complexes: An electron paramagnetic resonance investigation

    Science.gov (United States)

    Domracheva, N. E.; Mirea, A.; Schwoerer, M.; Torre-Lorente, L.; Lattermann, G.

    2007-07-01

    New nanostructured materials, namely, the liquid-crystalline copper(II) complexes that contain poly(propylene imine) dendrimer ligands of the first (ligand 1) and second (ligand 2) generations and which have a columnar mesophase and different copper contents (x = Cu/L), are investigated by EPR spectroscopy. The influence of water molecules and nitrate counterions on the magnetic properties of complex 2 (x = 7.3) is studied. It is demonstrated that water molecules can extract some of the copper ions from dendrimer complexes and form hexaaqua copper complexes with free ions. The dimer spectra of fully hydrated complex 2 (x = 7.3) are observed at temperatures T dendrimer copper(II) complex. The temperature-induced valence tautomerism attended by electron transport is revealed for the first time in blue dendrimer complexes 1 (x = 1.9) with a dimer structure. The activation energy for electron transport is estimated to be 0.35 meV. The coordination of the copper ion site (NO4) and the structural arrangement of green complexes 1 (x = 1.9) in the columnar mesophase are determined. Complexes of this type form linear chains in which nitrate counterions serve as bridges between copper centers. It is revealed that green complexes 1 (x = 1.9) dissolved in isotropic inert solvents can be oriented in the magnetic field (B 0 = 8000 G). The degree of orientation of these complexes is rather high (S z = 0.76) and close to that of systems with a complete ordering (S z = 1) in the magnetic field. Copper(0) nanoclusters prepared by reduction of complex 2 (x = 7.3) in two reducing agents (NaBH4, N2H4 · H2O) are examined. A model is proposed for a possible location of Cu(0) nanoclusters in a dendrimer matrix.

  1. Ferrofluids in liquid crystalline systems

    International Nuclear Information System (INIS)

    Figueiredo Neto, A.M.; Liebert, L.

    1989-08-01

    It is a well-known fact that intermediate or mesomorphic phase may exist between the crystalline and the isotropic liquid phases. The symmetry properties of these mesophases are intermediate between those of a crystal and a liquid. In this paper, some aspects of the use of ferrofluids in thermotropic and lyotropic systems are studied both the experimental difficulties as well as the fundamental phypical phenomena involved. (A.C.A.S.) [pt

  2. Preparations of spherical polymeric particles from Tanzanian ...

    African Journals Online (AJOL)

    Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of ...

  3. Polymerization and processing of organic polymers in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, E.P. [Los Alamos National Laboratory, NM (United States)

    1995-05-01

    The use of magnetic fields to affect the structure and properties of polymeric materials remains an area of great promise. Liquid crystalline polymers have been actively studied over the past 20 years for use in high performance structural applications. In particular, highly oriented fibers can exhibit remarkable increases in strength to weight performance compared to conventional materials. For example, the fibers marketed by DuPont under the tradename Kevlar are 20 times stronger than steel on an equivalent weight basis. However, larger bulk parts do not exhibit the same increases in strength due to a lack of orientation of the polymer molecules. Magnetic field processing of polymers remains an attractive solution to this problem.

  4. Elektroaktive polymerer

    DEFF Research Database (Denmark)

    West, K.

    Traditionelt tænker vi på polymerer (plastik) som elektrisk isolerende materialer - det som er udenpå ledningerne. I dag kender vi imidlertid også polymerer med intrinsisk elektrisk ledningsevne, og plast er på vej ind i anvendelser, der tidligereudelukkende var baseret på metaller og uorganiske...... halvledere. Hertil kommer, at en del af de ledende polymerer kan stimuleres til at skifte mellem en ledende og en halvledende tilstand, hvorved de ændret både form og farve. I foredraget gives der enrække eksempler på anvendelse af polymerer som elektriske komponenter - rækkende fra polymer elektronik over...

  5. Molecular Design for Preparation of Hexagonal-Ordered Porous Films Based on Side-chain Type Liquid-Crystalline Star Polymer.

    Science.gov (United States)

    Naka, Yumiko; Takayama, Hiromu; Koyama, Teruhisa; Le, Khoa V; Sasaki, Takeo

    2018-05-02

    Fabrication of regularly porous films by the breath-figure method has attracted much attention. The simple, low-cost technique uses the condensation of water droplets to produce these structures, but the phenomenon itself is complex, requiring control over many interacting parameters that change throughout the process. Developing a unified understanding for the molecular design of polymers to prepare ordered porous films is challenging, but required for further advancements. In this article, the effects of the chemical structure of polymers in the breath-figure technique were systematically explored using side-chain type liquid-crystalline (LC) star polymers. The formation of porous films was affected by the structure of the polymers. Although the entire film surface of poly(11-[4-(4-cyanobiphenyl)oxy]undecyl methacrylate) (P11CB) had a hexagonal ordered porous structure over a certain Mn value, regularly arranged holes did not easily form in poly(methyl methacrylate) (PMMA), even though the main chain of PMMA is similar to that of P11CB. Comparing P11CB and poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11B) (P11CB without cyano groups) showed that the local polar groups in hydrophobic polymers promoted the formation of ordered porous films. No holes formed in poly(4-cyanobiphenyl methacrylate) (P0CB) (P11CB without alkyl spacers) films due to its hydrophilicity. The introduction of alkyl chains in P0CB allowed the preparation of honeycomb-structured films by increasing the internal tension. However, alkyl chains in the side chain alone did not result in a porous structure, as in the case of poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11). Aromatic rings are also required to increase the Tg and improve film formability. In the present study, suitable molecular designs of polymers were found, specifically hydrophobic polymers with local polar groups, to form a regularly porous structure. Development of clear guidelines for the molecular

  6. Twin screw extruders as polymerization reactors for a free radical homo polymerization

    NARCIS (Netherlands)

    Ganzeveld, K.J.; Janssen, L.P.B.M.

    The bulk polymerization of n-butylmethacrylate was investigated in a counter-rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the

  7. Synthesis and Characterization of Ferroelectric Liquid Crystalline Organosiloxanes Containing 4-(4-undecanyloxy bi-phenyl-1-carboxyloxyphenyl (2S,3S-2-chloro-3-methylvalerate and 4-(4-undecanyloxybenzoyloxybiphenyl (2S,3S-2-chloro-3-methylvalerate

    Directory of Open Access Journals (Sweden)

    Chih-Hung Lin

    2013-10-01

    Full Text Available A series of new organosiloxane ferroelectric liquid crystalline (FLC materials have been synthesized, and their mesomorphic and physical properties have been characterized. Four new disiloxanes and trisiloxanes, containing biphenyl 4-hydroxybenzoate and phenyl 4-hydroxybiphenylcarboxylate as mesogenic units and eleven methylene unit as spacers and (2S,3S-2-chloro-3-methylvalerate unit as chiral end groups. The molecule, using three phenyl ring as a mesogenic unit, formulates much wider liquid crystalline phase temperature ranges than that of a two phenyl ring unit. The phenyl arrangement differences of mesogenic unit result in the greater differences of the liquid crystal phase formation. The siloxane molecule induction is helpful to the more regular smectic phase formation and smectic phase stabilization, such as chiral SC (SC* and SB phases. The siloxane molecule is helpful to reduce the phase transition temperature and broaden the liquid crystal temperature range of the SC* phase and, simultaneously, it will not induce chain crystallization phenomenon and dilute the Ps value. The synthesis and characterization of the new FLCs materials, which exhibit a room temperature SC* phase and higher spontaneous polarization are presented.

  8. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

    2015-01-01

    microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  9. Some problems of the statistical theory of polymeric lyotropic liquid crystals

    International Nuclear Information System (INIS)

    Grosberg, A.Yu.; Khokhlov, A.R.

    1980-06-01

    In this article we consider some topics of the statistical physics of liquid-crystalline phase in the solutions of stiff chain macromolecules. Among these topics are: the problem of the phase diagram for the liquid-crystalline transition in the solutions of completely stiff macromolecules (rigid rods); conditions of formation of the liquid-crystalline phase in the solutions of semiflexible macromolecules; possibility of the intramolecular liquid-crystalline ordering in semiflexible macromolecules; structure of intramolecular liquid crystals and dependence of the properties of the liquid-crystalline phase on the microstructure of the polymer chain. (author)

  10. Photoorientation of a liquid-crystalline polyester with azobenzene side groups: Effects of irradiation with linearly polarized red light after photochemical pretreatment

    DEFF Research Database (Denmark)

    Zebger, Ingo; Rutloh, Michael; Hoffmann, Uwe

    2003-01-01

    light. The polyester is characterized by smectic and nematic phases g24SX26SA34N46i and a strong tendency to form J-aggregates. The process requires a photochemical pretreatment by irradiation with UV light or an exposure to visible light of high power density to produce a certain concentration of the Z...

  11. Hierarchical self-assembly, coassembly, and self-organization of novel liquid crystalline lattices and superlattices from a twin-tapered dendritic benzamide and its four-cylinder-bundle supramolecular polymer.

    Science.gov (United States)

    Percec, Virgil; Bera, Tushar K; Glodde, Martin; Fu, Qiongying; Balagurusamy, Venkatachalapathy S K; Heiney, Paul A

    2003-02-17

    The synthesis and structural analysis of the twin-dendritic benzamide 10, based on the first-generation, self-assembling, tapered dendrons 3,4,5-tris(4'-dodecyloxybenzyloxy)benzoic acid and 3,4,5-tris(4'-dodecyloxybenzyloxy)-1-aminobenzene, and the polymethacrylate, 20, which contains 10 as side groups, are presented. Benzamide 10 self-assembles into a supramolecular cylindrical dendrimer that self-organizes into a columnar hexagonal (Phi(h)) liquid crystalline (LC) phase. Polymer 20 self-assembles into an imperfect four-cylinder-bundle supramolecular dendrimer, and creates a giant vesicular supercylinder that self-organizes into a columnar nematic (N(c)) LC phase which displays short-range hexagonal order. In mixtures of 20 and 10, 10 acts as a guest and 20 as a host to create a perfect four-cylinder-bundle host-guest supramolecular dendrimer that coorganizes with 10. A diversity of Phi(h), simple rectangular columnar (Phi(r-s)) and centered rectangular columnar (Phi(r-c)), superlattices are produced at different ratios between 20 and 10. This diversity of LC lattices and superlattices is facilitated by the architecture of the twin-dendritic building block, polymethacrylate, the host-guest supramolecular assembly, and by hydrogen bonding along the center of the supramolecular cylinders generated from 10 and 20.

  12. "Click" i polymerer 2

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2012-01-01

    "Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer......"Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer...

  13. Conducting Polymeric Materials

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2016-01-01

    The overall objective of this collection is to provide the most recent developments within the various areas of conducting polymeric materials. The conductivity of polymeric materials is caused by electrically charged particles, ions, protons and electrons. Materials in which electrons...

  14. Liquid crystalline networks for electroluminescent displays

    International Nuclear Information System (INIS)

    Contoret, A.E.A.

    2001-09-01

    This work presents the first low molar mass organic electroluminescent (EL) material to form a nematic glass and then emit plane-polarised light from the vitrified state on application of an electric field. Photocrosslinkable molecules are also discussed which form insoluble films on illumination with ultra-violet light. This approach combines the ease of deposition of small molecules with the robustness and stability of polymers, allowing simple fabrication of multi-layer EL devices and photo-patterning. A range of conjugated low molar-mass molecules are considered, containing the anthracene, perylene and fluorene cores, with the aims of producing a general recipe for efficient EL, based on ordered, stable nematics at room temperature. Many physical properties are compared and molecular mechanics modeling is used to represent molecular geometries. An acrylate and several diene photo-polymerisable derivatives of the fluorenes undergo photo-crosslinking. Infrared and photoluminescence spectroscopy is used to examine crosslinking in detail and to optimise exposure conditions. The diene shows no significant degradation for an optimal exposure, but requires a high fluence of 100 Jcm -2 to form an insoluble film. A doped photo-alignment layer is used for the first time to obtain polarised El with ratio 11:1 and 80 cdm -2 brightness from the crosslinked diene. The insoluble crosslinked network allows spin coating of an electron transporting over-layer, resulting in increased brightness. Complex impedance spectroscopy and time of flight measurements confirm good material properties with complete depletion of the crosslinkable diene molecule and non-dispersive conduction. Finally, a novel deposition technique, pulsed laser deposition (PLD), is presented, as an alternative to spin coating or vapour deposition. Minimal degradation is observed for optimised deposition conditions and a PLD film is successfully demonstrated in an EL device. (author)

  15. Synthesis and characterization of thermotropic liquid crystalline ...

    Indian Academy of Sciences (India)

    In the present work, due to the absence of branching in diamine-based mesogen, the structure has—rigidity inversely ... (Model: Spectrum GX and serial number: 69229). Number ..... logical applications, micro-rheological study on fully exfoli-.

  16. Molecular Engineering of Liquid Crystalline Polymers

    Science.gov (United States)

    1992-03-27

    Szasz , N. Sheppard and D. H. Rank, J. Chem. Phys., 1948, 16..704 119. P. B. Woller and E. W. Garbisch, Jr., J. Am. Chem. Soc., 1972, 94, 53 10 120. A. L...schematic representation of a sanidic (from Greek for boardlike) mesophase.202 Figure 15. a) Layer spacing d calculated according to Bragg’s law

  17. Stimuli-responsive liquid crystalline materials

    NARCIS (Netherlands)

    Debije, M.G.; Schenning, A.P.H.J.; Hashmi, Saleem

    2016-01-01

    Stimuli-responsive materials which respond to triggers from the environment by changing their properties are one of the focal points in materials science. For precise functional properties, well-defined hierarchically ordered supramolecular materials are crucial. The self-assembly of liquid crystals

  18. Electrically Reconfigurable Liquid Crystalline Mirrors (Postprint)

    Science.gov (United States)

    2018-04-24

    focus on dynamic reconfiguration of the reflection band gap of polymer-stabilized cholesteric liquid crystals (PSCLCs). Recent research has reported the...public release: distribution unlimited. © 2018 AMERICAN CHEMICAL SOCIETY (STINFO COPY) AIR FORCE RESEARCH LABORATORY MATERIALS AND MANUFACTURING...MONITORING AGENCY ACRONYM(S) Air Force Research Laboratory Materials and Manufacturing Directorate Wright-Patterson Air Force Base, OH

  19. Silicon dioxide obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    Oliveira, C.T.; Granado, S.R.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The Polymeric Precursor Method is able for obtaining several oxide material types with high surface area even obtained in particle form. Several MO 2 oxide types such as titanium, silicon and zirconium ones can be obtained by this methodology. In this work, the synthesis of silicon oxide was monitored by thermal analysis, XRD and surface area analysis in order to demonstrate the influence of the several synthesis and calcining parameters. Surface area values as higher as 370m2/g and increasing in the micropore volume nm were obtained when the material was synthesized by using ethylene glycol as polymerizing agent. XRD analysis showed that the material is amorphous when calcinated at 600°C in despite of the time of calcining, but the material morphology is strongly influenced by the polymeric resin composition. Using Glycerol as polymerizing agent, the pore size increase and the surface area goes down with the increasing in decomposition time, when compared to ethylene glycol. (author)

  20. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng

    2015-09-01

    In the recent rise of metal-free polymerization techniques, organic phosphazene superbases have shown their remarkable strength as promoter/catalyst for the anionic polymerization of various types of monomers. Generally, the complexation of phosphazene base with the counterion (proton or lithium cation) significantly improves the nucleophilicity of the initiator/chain end resulting in highly enhanced polymerization rates, as compared with conventional metalbased initiating systems. In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges and perspectives being pointed out.

  1. Applied bioactive polymeric materials

    CERN Document Server

    Carraher, Charles; Foster, Van

    1988-01-01

    The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

  2. PREFACE: IUMRS-ICA 2008 Symposium, Sessions 'X. Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science' and 'Y. Frontier of Polymeric Nano-Soft-Materials - Precision Polymer Synthesis, Self-assembling and Their Functionalization'

    Science.gov (United States)

    Takahara, Atsushi; Kawahara, Seiichi

    2009-09-01

    aimed to provide recent advances in polymer synthesis, self-assembling processes and morphologies, and functionalization of nano-soft-materials in order to initiate mutual and collaborative research interest that is essential to develop revolutionarily new nano-soft-materials in the decades ahead. Four Keynote lectures, 15 invited talks and 30 posters presented important new discoveries in polymeric nano-soft-materials, precision polymer synthesis, self-assembling and their functionalization. As for the precision polymer synthesis, the latest results were provided for studies on synthesis of polyrotaxane with movable graft chains, organic-inorganic hybridization of polymers, supra-molecular coordination assembly of conjugated polymers, precision polymerization of adamantane-containing monomers, production of high density polymer brush and synthesis of rod coil type polymer. The state-of-the-art results were introduced for the formation of nano-helical-structure of block copolymer containing asymmetric carbon atoms, self-assembling of block copolymers under the electric field, self-assembling of liquid crystalline elastomers, preparation of nano cylinder template films and mesoscopic simulation of phase transition of polymers and so forth. Moreover, recent advantages of three-dimensional electron microtomography and scanning force microscopy were proposed for analyses of nano-structures and properties of polymeric multi-component systems. Syntheses, properties and functions of slide-ring-gel, organic-inorganic hybrid hydrogels, hydrogel nano-particles, liquid-crystalline gels, the self-oscillating gels, and double network gels attracted participants' attention. Modifications of naturally occurring polymeric materials with supercritical carbon dioxide were introduced as a novel technology. Some of the attractive topics are presented in this issue. We are grateful to all the speakers and participants for valuable contributions and active discussions. Organizing committee

  3. <strong>Mini-project>

    DEFF Research Database (Denmark)

    Katajainen, Jyrki

    2008-01-01

    In this project the goal is to develop the safe * family of containers for the CPH STL. The containers to be developed should be safer and more reliable than any of the existing implementations. A special focus should be put on strong exception safety since none of the existing prototypes available...

  4. A novel process for ultrasound-induced radical polymerization in CO2-expanded fluids

    NARCIS (Netherlands)

    Kemmere, M.F.; Kuijpers, M.W.A.; Prickaerts, R.M.H.; Keurentjes, J.T.F.

    2005-01-01

    A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. In this work, ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA in order to reduce the

  5. Influence of CO2 on ultrasound-induced polymerizations in high-pressure fluids

    NARCIS (Netherlands)

    Kuijpers, M.W.A.; Jacobs, L.J.M.; Kemmere, M.F.; Keurentjes, J.T.F.

    2005-01-01

    A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. Ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA, as well as in bulk MMA. For this

  6. Strong interactions

    International Nuclear Information System (INIS)

    Froissart, Marcel

    1976-01-01

    Strong interactions are introduced by their more obvious aspect: nuclear forces. In hadron family, the nucleon octet, OMEGA - decuplet, and quark triply are successively considered. Pion wave having been put at the origin of nuclear forces, low energy phenomena are described, the force being explained as an exchange of structure corresponding to a Regge trajectory in a variable rotating state instead of the exchange of a well defined particle. At high energies the concepts of pomeron, parton and stratons are introduced, pionization and fragmentation are briefly differentiated [fr

  7. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers. Alt...

  8. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng; Hadjichristidis, Nikolaos; Schlaad, Helmut

    2015-01-01

    . In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges

  9. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  10. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  11. STUDIES ON VINYL POLYMERIZATION WITH INITIATION SYSTEM CONTAINING AMINE DERIVATIVES

    Institute of Scientific and Technical Information of China (English)

    QIU Kunyuan; ZHANG Jingyi; FENG Xinde(S. T. Voong)

    1983-01-01

    Two main types of amine-containing initiation systems were studied in this work. In the case of MMA polymerization initiated by BPO-amine (DMT, DHET, DMA) redox systems, it was found that the polymerization rate and colour stability of the polymer for different amine systems were in the following order: DMT≈DHET>DMA. Accordingly, BPO-DMT and BPO-DHET are effective initiators. In the case of MEMA polymerization by amine (DMT, DHET, DMA) alone, it was found that the polymerization rate and the percentage of conversion for these different amine systems were in the following order: DMT≥DHET>DMA. The polymerization rate and the percentage of conversion also increased with the increase of DMT concentration. From the kinetic investigation the rate equation of Rp=K [DMT]1/2 [MEMA]3/2 was obtained, and the overall activation energy of polymerization was calculated to be 34.3 KJ/mol (8.2 Kcal/mol). Moreover, the polymerization of MEMA in the presence of DMT was strongly inhibited by hydroquinone, indicating the polymerization being free radical in nature. From these results, the mechanism of MEMA polymerization initiated by amine was proposed.

  12. Radiation induced emulsion polymerization

    International Nuclear Information System (INIS)

    Stannett, V.T.; Stahel, E.P.

    1990-01-01

    High energy radiation is particularly favored for the initiation of emulsion polymerization. The yield of free radicals, for example, from the radiolysis of the aqueous phase, is high; G(radical) values of 5-7. In addition, the rather special kinetics associated with emulsion polymerization lead, in general, to very large kinetic chain lengths, even with 'non-ideal' monomers such as vinyl acetate. Together, high polymerization rates at low doses become possible. There are some important advantages of radiation polymerization compared with chemical initiators, such as potassium persulfate. Perhaps the most important among them is the temperature independence of the initiation step. This makes low temperature polymerization very accessible. With monomers such as vinyl acetate, where chain termination to monomer is predominant, low temperatures lead to often highly desirable higher molecular weights. With styrene, the classical ideally behaved monomer, there are the advantages such as, for example, the feasibility of using cationic monomers. These and some attendant disadvantages are discussed in detail, including pilot plant studies

  13. Plasma polymerization by Softplasma

    DEFF Research Database (Denmark)

    Jiang, J.; Wu, Zhenning; Benter, Maike

    2008-01-01

    , external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous......In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...

  14. Inflation of a Polymeric Menbrane

    DEFF Research Database (Denmark)

    Kristensen, Susanne B.; Larsen, Johannes R.; Hassager, Ole

    1998-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane.......We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane....

  15. Reversible and Irreversible Binding of Nanoparticles to Polymeric Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang H. Binder

    2009-01-01

    Full Text Available Reversible and irreversible binding of CdSe-nanoparticles and nanorods to polymeric surfaces via a strong, multiple hydrogen bond (= Hamilton-receptor/barbituric acid is described. Based on ROMP-copolymers, the supramolecular interaction on a thin polymer film is controlled by living polymerization methods, attaching the Hamilton-receptor in various architectures, and concentrations. Strong binding is observed with CdSe-nanoparticles and CdSe-nanorods, whose surfaces are equipped with matching barbituric acid-moieties. Addition of polar solvents, able to break the hydrogen bonds leads to the detachment of the nanoparticles from the polymeric film. Irreversible binding is observed if an azide/alkine-“click”-reaction is conducted after supramolecular recognition of the nanoparticles on the polymeric surface. Thus reversible or irreversible attachment of the nanosized objects can be achieved.

  16. Polymerized and functionalized triglycerides

    Science.gov (United States)

    Plant oils are useful sustainable raw materials for the development of new chemical products. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a new method for polymerizing epoxidized triglycerides with the use of fluorosulfonic acid. Depending on the ...

  17. Polymerization by radiation. Application

    International Nuclear Information System (INIS)

    Romero, M.; Fernandez Miranda, J.

    1997-01-01

    Achieved results of the research work done in the field of radiation polymerization are summarized. Developing new chromatographic matrices, the radiation grafting of Glycidyl methacrylate on the surface of Low Density Polyethylene beads was studied. The dependence of both, the grafted degree and width of the grafted layer, with the radiation dose applied, is presented

  18. RAFT polymerization mediated bioconjugation strategies

    OpenAIRE

    Bulmuş, Volga

    2011-01-01

    This review aims to highlight the use of RAFT polymerization in the synthesis of polymer bioconjugates. It covers two main bioconjugation strategies using the RAFT process: (i) post-polymerization bioconjugations using pre-synthesized reactive polymers, and (ii) bioconjugations via in situ polymerization using biomolecule-modified monomers or chain transfer agents. © 2011 The Royal Society of Chemistry.

  19. Radiation polymerization of tetrafluoroethylene

    International Nuclear Information System (INIS)

    Kadoi, H.; Lugao, A.B.; Oikawa, H.

    1984-01-01

    Tetrafluoroethylene (TFE) monomer was obtained by means of the pyrolysis of chlorodifluoromethane (R-22). The experiments were carried out in quartz tube with temperature between 700 0 and 800 0 C. The principal reaction of the pyrolysis is considered to be: 2CHClF2 ----> C 2 F 4 +2HCl. However, by-products such as HF, C 3 F 6 , C 2 HClF 4 , C 4 F 8 etc are also produced in the pyrolysis process. The conversions of R-22 varied from 30 to 50%, depending upon the temperature, pressure and flow rate of R-22 in the furnace. Finally the TFE monomer of purity higher than 99.98% was obtained by fractional distillation in low temperatures ranging from -10 0 to -30 0 C. The bulk polymerization of this monomer induced by γ-rays from 3000Ci cobalt-60 source was studied at various temperatures (room temperature, 0 0 , -23 0 and -78 0 C). The monomers were introduced into stainless steel vessels of 15 and 60 ml volume under vacuum. The control of polymerization reaction was rather hard at temperatures higher than -23 0 C due to the difficulty of removing the heat of reaction. However, the polymerization at -78 0 C was very easy to control. The white polymer particles were obtained in agglomerated state. The IR spectra of the polymers were consistent with those of commercial products. The melting points of samples were between 326 0 and 331 0 C. (Author) [pt

  20. Radiation chemistry of polymeric system

    International Nuclear Information System (INIS)

    Machi, Sueo; Ishigaki, Isao

    1978-01-01

    Among wide application of radiation in the field of polymer chemistry, practices of polymerization, graft polymerization, bridging, etc. are introduced hereinafter. As for the radiation sources of radiation polymerization, in addition to the 60 Co-γ ray with long permeation distance which has been usually applied, electron beam accelerators with high energy, large current and high reliability have come to be produced, and the liquid phase polymerization by electron beam has attracted attention industrially. Concerning polymerizing reactions, explanations were given to electron beam polymerization under high dose rate, the polymerization in supercooling state or under high pressure, and emulsifying polymerization. As for radiation bridging, radiation is applied for the bridging of hydrogel, acceleration of bridging and improvement of radiation resistance. It is also utilized for reforming membranes by graft polymerization, and synthesis of polymers for medical use. Application of fixed enzymes in the medical field has been investigated by fixing various enzymes by low temperature γ-ray polymerization with glassy monomers such as HEMA. (Kobatake, H.)

  1. Light-harvesting organic photoinitiators of polymerization.

    Science.gov (United States)

    Lalevée, Jacques; Tehfe, Mohamad-Ali; Dumur, Frédéric; Gigmes, Didier; Graff, Bernadette; Morlet-Savary, Fabrice; Fouassier, Jean-Pierre

    2013-02-12

    Two new photoinitiators with unprecedented light absorption properties are proposed on the basis of a suitable truxene skeleton where several UV photoinitiators PI units such as benzophenone and thioxanthone are introduced at the periphery and whose molecular orbitals MO can be coupled with those of the PI units: a red-shifted absorption and a strong increase of the molecular extinction coefficients (by a ≈ 20-1000 fold factor) are found. These compounds are highly efficient light-harvesting photoinitiators. The scope and practicality of these photoinitiators of polymerization can be dramatically expanded, that is, both radical and cationic polymerization processes are accessible upon very soft irradiation conditions (halogen lamp, LED…︁) thanks to the unique light absorption properties of the new proposed structures. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Packaging based on polymeric materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2005-01-01

    Full Text Available In the past two years the consumption of common in the developed countries world wide (high tonnage polymers for packaging has approached a value of 50 wt.%. In the same period more than 50% of the packaging units on the world market were made of polymeric materials despite the fact that polymeric materials present 17 wt.% of all packaging materials. The basic properties of polymeric materials and their environmental and economical advantages, providing them such a position among packaging materials, are presented in this article. Recycling methods, as well as the development trends of polymeric packaging materials are also presented.

  3. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  4. Synthesis of magnetic polymeric microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2010-05-13

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  5. Synthesis of magnetic polymeric microspheres

    International Nuclear Information System (INIS)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I

    2010-01-01

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  6. Mechanocatalytic polymerization and cross-linking in a polymeric matrix

    NARCIS (Netherlands)

    Jakobs, R.T.M.; Ma, Shuang; Sijbesma, R.P.

    2013-01-01

    A latent olefin metathesis catalyst, bearing two polymeric NHC ligands, was embedded in a semicrystalline polymer matrix containing cyclic olefins. The catalyst was activated by straining the solid material under compression, resulting in polymerization and cross-linking reactions of the monomers in

  7. Radiation-induced graft polymerization of amphiphilic monomers with different polymerization characteristics onto hydrophobic polysilane

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hidenori; Iwasaki, Isao; Kunai, Yuichiro [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Sato, Nobuhiro, E-mail: sato-n@rri.kyoto-u.ac.j [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Matsuyama, Tomochika [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2011-08-15

    The structures of poly(methyl-n-propylsilane) (PMPrS) amphiphilically modified through {gamma}-ray-induced graft polymerization were investigated with {sup 1}H NMR measurement. By the use of methyl methacrylate (MMA) or diethyl fumarate (DEF) as monomers for the graft polymerization, grafting yield rose with increasing total absorption dose and monomer concentrations, but decreased with increasing dose rate. This result means that grafting yield of modified PMPrS can be controlled by changing irradiation conditions. However, the number of PMMA or PDEF graft chains per PMPrS chain was estimated to be less than 1.0 by analysis of {sup 1}H NMR spectra, and this value was lower than that we had expected. To improve graft density, maleic anhydride (MAH), which is known as a non-homopolymerizable monomer in radical polymerization, was used as a monomer for grafting. As a result, high density grafting (one MAH unit for 4.2 silicon atoms) was attained. It demonstrates that the structure of {gamma}-ray-modified polysilane strongly depends on the polymerization characteristics of grafted monomers.

  8. Collaborative Research: Polymeric Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shenqiang [Temple Univ., Philadelphia, PA (United States). College of Engineering

    2017-04-20

    The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of molecular charge-transfer crystals has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer solids. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PI seeks to fundamental understanding of the control of organic crystals to demonstrate and explore room temperature multiferroicity. The experimental results have been verified through the theoretical modeling.

  9. Polymerization with freezing

    International Nuclear Information System (INIS)

    Ben-Naim, E; Krapivsky, P L

    2005-01-01

    Irreversible aggregation processes involving reactive and frozen clusters are investigated using the rate equation approach. In aggregation events, two clusters join irreversibly to form a larger cluster; additionally, reactive clusters may spontaneously freeze. Frozen clusters do not participate in merger events. Generally, freezing controls the nature of the aggregation process, as demonstrated by the final distribution of frozen clusters. The cluster mass distribution has a power-law tail, F k ∼k -γ , when the freezing process is sufficiently slow. Different exponents, γ = 1 and 3, are found for the constant and the product aggregation rates, respectively. For the latter case, the standard polymerization model, either no gels, or a single gel, or even multiple gels, may be produced

  10. Hyper-cross-linked, hybrid membranes via interfacial polymerization

    NARCIS (Netherlands)

    Raaijmakers, Michiel

    2015-01-01

    Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on

  11. Polymeric micelles for drug targeting.

    Science.gov (United States)

    Mahmud, Abdullah; Xiong, Xiao-Bing; Aliabadi, Hamidreza Montazeri; Lavasanifar, Afsaneh

    2007-11-01

    Polymeric micelles are nano-delivery systems formed through self-assembly of amphiphilic block copolymers in an aqueous environment. The nanoscopic dimension, stealth properties induced by the hydrophilic polymeric brush on the micellar surface, capacity for stabilized encapsulation of hydrophobic drugs offered by the hydrophobic and rigid micellar core, and finally a possibility for the chemical manipulation of the core/shell structure have made polymeric micelles one of the most promising carriers for drug targeting. To date, three generations of polymeric micellar delivery systems, i.e. polymeric micelles for passive, active and multifunctional drug targeting, have arisen from research efforts, with each subsequent generation displaying greater specificity for the diseased tissue and/or targeting efficiency. The present manuscript aims to review the research efforts made for the development of each generation and provide an assessment on the overall success of polymeric micellar delivery system in drug targeting. The emphasis is placed on the design and development of ligand modified, stimuli responsive and multifunctional polymeric micelles for drug targeting.

  12. Organometallic Polymeric Conductors

    Science.gov (United States)

    Youngs, Wiley J.

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for

  13. An Asymmetric Runaway Domain Swap Antithrombin Dimer as a Key Intermediate for Polymerization Revealed by Hydrogen/Deuterium-Exchange Mass Spectrometry

    DEFF Research Database (Denmark)

    Trelle, Morten Beck; Pedersen, Shona H; Østerlund, Eva Christina

    2017-01-01

    Antithrombin deficiency is associated with increased risk of venous thrombosis. In certain families, this condition is caused by pathogenic polymerization of mutated antithrombin in the blood. To facilitate future development of pharmaceuticals against antithrombin polymerization, an improved und...... strongly supports a β4A-β5A β-hairpin runaway domain swap mechanism for antithrombin polymerization. HDX-MS thus holds exceptional promise as an enabling analytical technique in the efforts toward future pharmacological intervention with protein polymerization and associated diseases....

  14. Bidimensional distortion in ferroelectric liquid crystals with strong ...

    Indian Academy of Sciences (India)

    characterized by bistability and optical memory in the surface-stabilized bookshelf [2,3] ... tic layers, which lies in a plane parallel to the cell walls (see figure 1). Up to now ... Theory. We consider a liquid crystalline material exhibiting ferroelectric phase organized in book- ... By applying an external electric field Eext along.

  15. Spin-crossover behavior of polymeric iron(III) complexes

    International Nuclear Information System (INIS)

    Maeda, Yonezo; Miyamoto, Makoto; Takashima, Yoshimasa; Oshio, Hiroaki

    1989-01-01

    Polymeric spin-crossover iron(III) complexes possessing poly(4-vinylpyridine), poly(N-vinylimidazole) or poly(octylmethacrylate-co-4-vinylpyridine) as ligand are prepared. In this experience enriched 57 Fe was used to get strong Moessbauer absorption. The enriched behavior of the complexes were examined by magnetic susceptibilities measurement, and Moessbauer and esr spectroscopies. Some of them show spin-state behavior over a wide range of temperature. Some of them show rapid spin-state interexchange compared to the Moessbauer time scale and others not. Spin-crossover behavior of polymeric complexes is characterized of wide spin-state transition temperature range

  16. De fysica van polymere materialen

    NARCIS (Netherlands)

    Struik, L.C.E.

    1987-01-01

    Rede, uitgesproken ter gelegenheid van de aanvaarding van het ambt van buitengewoon hoogleraar in de fysica van polymere materialen aan de Universitelt Twente op donderdag 22 januarì 1987 door Dr.lr. L.C.E. Struik.

  17. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng; Hadjichristidis, Nikolaos; Gnanou, Yves

    2014-01-01

    .e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  18. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Zhao, Junpeng; Zhang, Hefeng; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands

  19. Pulsed-laser polymerization in compartmentalized liquids. 1. Polymerization in vesicles

    NARCIS (Netherlands)

    Jung, M.; Casteren, van I.A.; Monteiro, M.J.; Herk, van A.M.; German, A.L.

    2000-01-01

    Polymerization in vesicles is a novel type of polymerization in heterogeneous media, leading to parachute-like vesicle-polymer hybrid morphologies. To explore the kinetics of vesicle polymerizations and to learn more about the actual locus of polymerization we applied the pulsed-laser polymerization

  20. Polyolefin nanocomposites in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine, E-mail: griselda.barrera@ufrgs.br [Universidade Federal do Rio Grande de Sul - UFRGS, Porto Alegre, RS (Brazil); Basso, Nara R.S. [Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Quijada, Raul [Universidad de Chile, Santiago (Chile)

    2011-07-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  1. Polyolefin nanocomposites in situ polymerization

    International Nuclear Information System (INIS)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine; Basso, Nara R.S.; Quijada, Raul

    2011-01-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  2. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  3. Dielectric loss property of strong acids doped polyaniline (PANi)

    Science.gov (United States)

    Amalia, Rianti; Hafizah, Mas Ayu Elita; Andreas, Manaf, Azwar

    2018-04-01

    In this study, strong acid doped polyaniline (PANi) has been successfully fabricated through the chemical oxidative polymerization process with various polymerization times. Nonconducting PANi resulting from the polymerization process at various polymerization times were then doped by a strong acid HClO4 to generate dielectric properties. Ammonium Persulfate (APS) as an initiator was used during Polymerization process to develop dark green precipitates which then called Emeraldine Base Polyaniline (PANi-EB). The PANi-EB was successively doped by strong acid HClO4 with dopant and PANi ratio 10:1 to enhance the electrical conductivity. The conductivity of doped PANi was evaluated by Four Point Probe. Results of evaluation showed that the conductivity values of HClO4 doped PANi were in the range 337-363 mS/cm. The dielectric properties of doped PANi were evaluated by Vector Network Analyzer (VNA) which suggested that an increase in the permittivity value in the conducting PANi. It is concluded that PANi could be a potential candidate for electromagnetic waves absorbing materials.

  4. Architecture of Amylose Supramolecules in Form of Inclusion Complexes by Phosphorylase-Catalyzed Enzymatic Polymerization

    Directory of Open Access Journals (Sweden)

    Jun-ichi Kadokawa

    2013-07-01

    Full Text Available This paper reviews the architecture of amylose supramolecules in form of inclusion complexes with synthetic polymers by phosphorylase-catalyzed enzymatic polymerization. Amylose is known to be synthesized by enzymatic polymerization using α-d-glucose 1-phosphate as a monomer, by phosphorylase catalysis. When the phosphorylase-catalyzed enzymatic polymerization was conducted in the presence of various hydrophobic polymers, such as polyethers, polyesters, poly(ester-ether, and polycarbonates as a guest polymer, such inclusion supramolecules were formed by the hydrophobic interaction in the progress of polymerization. Because the representation of propagation in the polymerization is similar to the way that a vine of a plant grows, twining around a rod, this polymerization method for the formation of amylose-polymer inclusion complexes was proposed to be named “vine-twining polymerization”. To yield an inclusion complex from a strongly hydrophobic polyester, the parallel enzymatic polymerization system was extensively developed. The author found that amylose selectively included one side of the guest polymer from a mixture of two resemblant guest polymers, as well as a specific range in molecular weights of the guest polymers poly(tetrahydrofuran (PTHF in the vine-twining polymerization. Selective inclusion behavior of amylose toward stereoisomers of chiral polyesters, poly(lactides, also appeared in the vine-twining polymerization.

  5. Preparation and Applications of Amylose Supramolecules by Means of Phosphorylase-Catalyzed Enzymatic Polymerization

    Directory of Open Access Journals (Sweden)

    Jun-ichi Kadokawa

    2012-01-01

    Full Text Available This paper reviews preparation and applications of amylose supramolecules by means of phosphorylase-catalyzed enzymatic polymerization. When the enzymatic polymerization of α-d-glucose 1-phosphate (G-1-P as a monomer was carried out in the presence of poly(tetrahydrofuran (PTHF of a hydrophobic polyether as a guest polymer, the supramolecule, i.e., an amylose-PTHF inclusion complex, was formed in the process of polymerization. Because the representation of propagation in the polymerization is similar to the way that vines of plants grow twining around rods, this polymerization method for the preparation of amylose-polymer inclusion complexes was proposed to be named “vine-twining polymerization”. Various hydrophobic polyethers, polyesters, poly(ester-ether, and polycarbonates were also employed as the guest polymer in the vine-twining polymerization to produce the corresponding inclusion complexes. To obtain the inclusion complex from a strongly hydrophobic guest polymer, the parallel enzymatic polymerization system was developed as an advanced extension of the vine-twining polymerization. In addition, it was found that amylose selectively includes one side of the guest polymer from a mixture of two resemblant guest polymers, as well as a specific range in molecular weights of the guest PTHF. Amylose also exhibited selective inclusion behavior toward stereoisomers of poly(lactides. Moreover, the preparation of hydrogels through the formation of inclusion complexes of amylose in vine-twining polymerization was achieved.

  6. Biodegradable Polyelectrolyte Obtained by Radiation Polymerization

    International Nuclear Information System (INIS)

    Craciun, G.; Martin, D.; Manaila, E.; Nemtanu, M.; Brasoveanu, M.; Ighigeanu, D.

    2009-01-01

    Poly electrolytes are water-soluble polymers carrying ionic charge along the polymer chain. Depending upon the charge, these polymers are anionic or cationic. The inherent solid - liquid separating efficiency makes these poly electrolytes a unique class of polymers which find extensive application in potable water, industrial raw and process water, municipal sewage treatment, mineral processing and metallurgy, oil drilling and recovery, etc. Also, due to their ability to produce advanced induced coagulation, a considerable amount of bacteria and viruses are precipitated together with the suspended solids. Especially the acrylamide polymers are very efficacious for water treatment but acrylamide is a toxic monomer and therefore their use are governed by international standards that provide the residual acrylamide monomer content (RAMC) in them be less than 0.05%. Under these circumstances our attention was focused on the following research steps that are presented in this paper: 1) Preparation of a special class of poly electrolytes, named Pn, with very low RAMC values, based on electron beam (EB), microwave (MW) and EB + MW induced co-polymerization of aqueous solutions containing appropriate mixtures of acrylamide (AMD) and acrylic acid (AA) monomers (AMD - AA co-polymers). The Pn were obtained by radiation technology with very small RAMC (under 0.01%) as well as in a wide range of molecular weights and charge densities. Very low AMD monomer content of Pn is due to the major advantages of radiation induced polymerization in aqueous solution containing monomers. Due to water presence in the EB irradiated system, irradiated water radicals facilitate the polymerization process and increase rate and level of monomers conversion in co-polymers. Also, once again, by the presence of water, which absorbs MW energy very strongly, the MW polymerization reaction rate is much enhanced resulting in a reaction time about 50-100 times lowers than by conventional heating. Also

  7. Factors affecting toxicity and efficacy of polymeric nanomedicines

    International Nuclear Information System (INIS)

    Igarashi, Eiki

    2008-01-01

    Nanomedicine is the application of nanotechnology to medicine. The purpose of this article is to review common characteristics of polymeric nanomedicines with respect to passive targeting. We consider several biodegradable polymeric nanomedicines that are between 1 and 100 nm in size, and discuss the impact of this technology on efficacy, pharmacokinetics, toxicity and targeting. The degree of toxicity of polymeric nanomedicines is strongly influenced by the biological conditions of the local environment, which influence the rate of degradation or release of polymeric nanomedicines. The dissemination of polymeric nanomedicines in vivo depends on the capillary network, which can provide differential access to normal and tumor cells. The accumulation of nanomedicines in the microlymphatics depends upon retention time in the blood and extracellular compartments, as well as the type of capillary endothelium surrounding specific tissues. Finally, the toxicity or efficacy of intact nanomedicines is also dependent upon tissue type, i.e., non-endocrine or endocrine tissue, spleen, or lymphatics, as well as tumor type

  8. Injectable biomimetic liquid crystalline scaffolds enhance muscle stem cell transplantation

    Science.gov (United States)

    Sleep, Eduard; McClendon, Mark T.; Preslar, Adam T.; Chen, Charlotte H.; Sangji, M. Hussain; Pérez, Charles M. Rubert; Haynes, Russell D.; Meade, Thomas J.; Blau, Helen M.; Stupp, Samuel I.

    2017-01-01

    Muscle stem cells are a potent cell population dedicated to efficacious skeletal muscle regeneration, but their therapeutic utility is currently limited by mode of delivery. We developed a cell delivery strategy based on a supramolecular liquid crystal formed by peptide amphiphiles (PAs) that encapsulates cells and growth factors within a muscle-like unidirectionally ordered environment of nanofibers. The stiffness of the PA scaffolds, dependent on amino acid sequence, was found to determine the macroscopic degree of cell alignment templated by the nanofibers in vitro. Furthermore, these PA scaffolds support myogenic progenitor cell survival and proliferation and they can be optimized to induce cell differentiation and maturation. We engineered an in vivo delivery system to assemble scaffolds by injection of a PA solution that enabled coalignment of scaffold nanofibers with endogenous myofibers. These scaffolds locally retained growth factors, displayed degradation rates matching the time course of muscle tissue regeneration, and markedly enhanced the engraftment of muscle stem cells in injured and noninjured muscles in mice. PMID:28874575

  9. Novel Colloidal and Dynamic Interfacial Phenomena in Liquid Crystalline Systems

    Science.gov (United States)

    2014-09-13

    Nicholas L. Abbott. Reduction in Wound Bioburden using a Silver-Loaded Dissolvable Microfilm Construct, Advanced Healthcare Materials, (06 2014): 916...d) International Conference on Nanoscience and Nanotechnology , Perth, Western Australia, February, 2012 (Plenary Lecture) Presentation #9 a...c) Abstract(s) (d) Exploratory Workshop on Defect-Assembled Soft Matter for Nanoscience and Nanotechnology , Rogaska Slatina, Slovenia

  10. Transport of Liquid Phase Organic Solutes in Liquid Crystalline Membranes

    OpenAIRE

    Han, Sangil

    2010-01-01

    Porous cellulose nitrate membranes were impregnated with 8CB and PCH5 LCs (liquid crystals) and separations of solutes dissolved in aqueous phases were performed while monitoring solute concentration via UV-VIS spectrometry. The diffusing organic solutes, which consist of one aromatic ring and various functional groups, were selected to exclude molecular size effects on the diffusion and sorption. We studied the effects on solute transport of solute intra-molecular hydrogen bonding and so...

  11. (Meth)acrylate liquid crystalline polymers for membrane applications

    Czech Academy of Sciences Publication Activity Database

    Rabie, F.; Sedláková, Zdeňka; Sheth, S.; Marand, E.; Martin, S. M.; Poláková, Lenka

    2015-01-01

    Roč. 132, č. 43 (2015), 42694_1-42694_8 ISSN 0021-8995 Institutional support: RVO:61389013 Keywords : copolymers * liquid crystals * membranes Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.866, year: 2015

  12. LIQUID CRYSTALLINE POLYMERS FROM VANILLIC ACID: SYNTHESIS, PROPERTIES, AND APPLICATIONS.

    NARCIS (Netherlands)

    Wilsens, Karel

    2017-01-01

    Thermotropic polyesters are an important class of materials for high erformance applications. Their low melt viscosities, low thermal expansion coefficients, high use temperatures, and ease in processing allow for the production of high strength and high modulus fibers, films, or compression-molded

  13. Frustrated smectic liquid crystalline phases in lactic acid derivatives

    Czech Academy of Sciences Publication Activity Database

    Glogarová, Milada; Novotná, Vladimíra

    2016-01-01

    Roč. 89, č. 7-8 (2016), s. 829-839 ISSN 0141-1594 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : field * liquid crystals * TGB phases Subject RIV: JJ - Other Materials Impact factor: 1.060, year: 2016

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

    DEFF Research Database (Denmark)

    Zebger, I; Rutloh, M; Hoffmann, U

    2002-01-01

    segments in the side- and main-chain. The very high values of the normalized linear dichroism up to 0.8 and the birefringence (above 0.3) are due to the interaction of photoorientation and thermotropic self-organization. The induction of anisotropy shows a pronounced dependence on the power density...

  15. Chirality under confinement - multidimensional constraints in liquid crystalline materials

    NARCIS (Netherlands)

    Sleczkowski, P.B.

    2014-01-01

    The first part of the thesis is devoted to studies of the self-assembled monolayers of discotic liquid crystals by the STM measurements at the liquid/solid interface. For the case of a model H5T molecule the self-assembled monolayers have evidenced both: point and organizational types of chirality,

  16. Iron Fibers Arrays Prepared by Electrodepositing in Reverse Liquid Crystalline

    Institute of Scientific and Technical Information of China (English)

    ZHAO Suling; LIN Dong; GUAN Jianguo; ZHANG Lianmeng

    2006-01-01

    Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using "FeSO4 solution-sodium caprylate-Decanol" 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft templates and the synthesized iron fibers were characterized by polarizing microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis etc. The experimental results show that the synthesized iron fibers with α crystal phase grew up in the form of fiber clusters of about 200 nm along the direction perpendicular to the cathode surface. Each cluster was composed of several tens of fibers. The fibers had almost the same length of more than 10 μm with a diameter of about 50 nm.

  17. Hydrodynamics of isotropic and liquid crystalline active polymer solutions.

    Science.gov (United States)

    Ahmadi, Aphrodite; Marchetti, M C; Liverpool, T B

    2006-12-01

    We describe the large-scale collective behavior of solutions of polar biofilaments and stationary and mobile crosslinkers. Both mobile and stationary crosslinkers induce filament alignment promoting either polar or nematic order. In addition, mobile crosslinkers, such as clusters of motor proteins, exchange forces and torques among the filaments and render the homogeneous states unstable via filament bundling. We start from a Smoluchowski equation for rigid filaments in solutions, where pairwise crosslink-mediated interactions among the filaments yield translational and rotational currents. The large-scale properties of the system are described in terms of continuum equations for filament and motor densities, polarization, and alignment tensor obtained by coarse-graining the Smoluchovski equation. The possible homogeneous and inhomogeneous states of the systems are obtained as stable solutions of the dynamical equations and are characterized in terms of experimentally accessible parameters. We make contact with work by other authors and show that our model allows for an estimate of the various parameters in the hydrodynamic equations in terms of physical properties of the crosslinkers.

  18. Investigations on the liquid crystalline phases of cation-induced

    Indian Academy of Sciences (India)

    ... most of the nonviral delivery vehicles are not effective for use in clinical system. ... Regional Research Laboratory, Thiruvananthapuram 695 019, India; Rajeev ... University of Medicine and Dentistry, Robert Wood Johnson Medical School, ...

  19. Dancing with light advances in photofunctional liquid-crystalline materials

    CERN Document Server

    Yu, Haifeng

    2015-01-01

    Recent progress in this field indicates that integrating photochromic molecules into LC materials enables one to photo-manipulate unique features such as photoinduced phase transition, photocontrolled alignment and phototriggered molecular cooperative motion, leading to their novel applications beyond displays. This book introduces readers to this field, from the primary- to the advanced level in photoresponsive LC materials. The subject is introduced step-by-step, including the basic knowledge of LCs, photoresponsive properties of LCs, and their detailed performances in the form of low-molecu

  20. Electro-optics of novel polymer-liquid crystalline composites

    International Nuclear Information System (INIS)

    Ibragimov, T.D.; Bayramov, G.M.; Imamaliyev, A.R.; Bayramov, G.M.

    2014-01-01

    The polymer network liquid crystals based on the liquid crystals H37 and 5CB with PMVP and PEG have been developed. Mesogene substance HOBA is served for stabilization of obtaining composites. Kinetics of network formation is investigated by methods of polarization microscopy and integrated small-angle scattering. It is shown that gel-like states of the composite H-37+PMVP+HOBA and 5CB+PEG+HOBA are formed at polymer concentration above 7 percent and 9 percent, correspondingly. The basic electro-optic parameters of the obtained composites are determined at room temperature. Experimental results are explained by phase separation of the system, diminution of a working area of electro-optical effects and influence of areas with high polymer concentration on areas with their low concentration

  1. Gold nanoparticles in plastic columnar discotic liquid crystalline material

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Mukesh, E-mail: mukeshphysics927@gmail.com [Center of Material Sciences, Institute of Interdisciplinary Studies, University of Allahabad, Allahabad 211002 (India); Kumar, Sandeep [Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India); Dhar, Ravindra, E-mail: dr.ravindra.dhar@gmail.com [Center of Material Sciences, Institute of Interdisciplinary Studies, University of Allahabad, Allahabad 211002 (India)

    2016-05-10

    Highlights: • Dispersion of Gold nanoparticles in a discotic liquid crystal has been studied. • σ{sub i} increases by seven orders of magnitude in the case of 1.2 wt% GNPs composites. • X-ray scattering results revel that a decrement in the core–core separation. • Study suggests that dispersion at low concentrations is uniform. • Band gap has decreased due to dispersion of GNPs in HAT4. - Abstract: We have studied the effect of gold nanoparticles (GNPs) on the thermodynamical, optical and dielectrical parameters of a discotic liquid crystal (DLC) namely hexabutyloxytriphenylene (HAT4). It has been observed that with the increase of GNPs concentration in DLC, composites shows two different regions. In the first regions i.e. low concentrations (<1 wt%), columnar hexagonal-isotropic (Col{sub hp}-I{sub L}) transition temperature and enthalpy (ΔH) decrease rapidly while in the second region i.e. higher concentrations (>1 wt%) Col{sub hp}-I{sub L} transition temperature and ΔH are approximately constant. It has been observed that, in the case of composites having 0.2 and 0.6 wt% of GNPs, conductivity has enhanced but it is poor as compared to the composite having 1.2 wt% of GNPs. For 1.2 wt% of GNPs, conductivity has increased by seven orders of magnitude as compared to the DLC. Optical study suggests that band gap of nanocomposites has decreased due to dispersion of GNPs.

  2. Synthesis and Characterization of Liquid Crystalline Epoxy Resins

    Science.gov (United States)

    2014-01-01

    greatly enhancing the matrix properties [1, 2]. In recent years, fiber reinforced polymer matrix composites (FRPs) have become one of the most important...Demand for Durable Polymer Matrix Composites: The National Academies Press, 2005. [9] Chung DDL. Carbon Fiber Composites: Butterworth- Heinemann , 1994...A-Polymer Chemistry 1993;31(9):2249-2260. [23] Jahromi S, Lub J, and Mol GN. Polymer 1994;35(3):622-629. [24] Hikmet RAM and Broer DJ. Polymer

  3. Thermotropic liquid crystalline polyesters derived from bis-(4 ...

    Indian Academy of Sciences (India)

    Administrator

    industry, construction industry, food containers as well as .... fluid. Excess thionyl chloride was removed by normal dis- tillation. The crude acid chloride was purified by double ... with mechanical stirrer, nitrogen inlet, and calcium chlo-.

  4. Lyotropic liquid crystalline nanoparticles of CoQ10

    DEFF Research Database (Denmark)

    Swarnakar, Nitin K; Thanki, Kaushik; Jain, Sanyog

    2014-01-01

    . The developed formulations were also found to be stable in simulated gastrointestinal fluids for the stipulated period of time. The in vitro drug release studies revealed a bimodal sustained release drug profile with Higuchi type release kinetics as the best fit release model for both the formulations. The best...

  5. Polymeric media for tritium fixation

    International Nuclear Information System (INIS)

    Franz, J.A.; Burger, L.L.

    1975-01-01

    The synthesis and leach testing of several polymeric media for tritium fixation are presented. Tritiated bakelite, poly(acrylonitrile) and polystyrene successfully fixed tritium. Tritium leach rates at the tracer level appear to be negligible. Advantages and disadvantages of the processes are discussed, and further bench-scale investigations underway are reported. Rough cost estimates are presented for the different media and are compared with alternate approaches such as deep-well injection and long-term tank storage. Polymeric media costs are high compared to deep-well storage and are of the same order of magnitude per liter of water as for isotopic enrichment. With this limitation, polymeric media can be economically feasible only for highly concentrated tritiated wastes. It is recommended that the bakelite and polystyrene processes be examined on a larger scale to permit more accurate cost analysis and process design. (auth)

  6. Olefin metathesis and metathesis polymerization

    CERN Document Server

    Ivin, K J

    1997-01-01

    This book is a follow-up to Ivins Olefin Metathesis, (Academic Press, 1983). Bringing the standard text in the field up to date, this Second Edition is a result of rapid growth in the field, sparked by the discovery of numerous well-defined metal carbene complexes that can act as very efficient initiators of all types of olefin metathesis reaction, including ring-closing metathesis of acyclic dienes, enynes, and dienynes; ring-opening metathesis polymerizationof cycloalkenes, acyclic diene metathesis polymerization; and polymerization of alkynes, as well as simple olefin metathesis. Olefin Metathesis and Metathesis Polymerization provides a broad, up-to-date account of the subject from its beginnings in 1957 to the latest applications in organic synthesis. The book follows the same format as the original, making it useful toteachers and to researchers, and will be of particular interest to those working in the fields of organic chemistry, polymer chemistry, organometallic chemistry, catalysis, materials scien...

  7. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  8. On-demand photoinitiated polymerization

    Science.gov (United States)

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  9. Pentafluorosulfanyl Substituents in Polymerization Catalysis.

    Science.gov (United States)

    Kenyon, Philip; Mecking, Stefan

    2017-10-04

    Highly electron-withdrawing pentafluorosulfanyl groups were probed as substituents in an organometallic catalyst. In Ni(II) salicylaldiminato complexes as an example case, these highly electron-withdrawing substituents allow for polymerization of ethylene to higher molecular weights with reduced branching due to significant reductions in β-hydrogen elimination. Combined with the excellent functional group tolerance of neutral Ni(II) complexes, this suppression of β-hydrogen elimination allows for the direct polymerization of ethylene in water to nanocrystal dispersions of disentangled, ultrahigh-molecular-weight linear polyethylene.

  10. Radiation Induced Polymerization of Pyrrole

    International Nuclear Information System (INIS)

    Sarada Idris; Ratnam, C.T.; Ahmad Ashrif Abu Bakar

    2016-01-01

    We demonstrate the polymerization of pyrrole by gamma irradiation. The pyrrole films were exposed to gamma ray from cobalt 60 source at doses ranging from 0 to 150 kGy. The films were subjected to structural and morphological analyses by using FTIR, SEM and AFM techniques. Similar studies were also made on pristine pyrrole film which serve as control. Results revealed that pyrrole has been successfully polymerized through irradiation induced reactions. The SEM images depicted the formation of cauliflower shape upon gamma irradiation. The structural changes of pyrrole also evidenced by FTIR spectra. Surface topography and roughness of pyrrole before and after gamma irradiation found to show significant differences. (author)

  11. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  12. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

  13. Numerical study of the thermal degradation of isotropic and anisotropic polymeric materials

    Energy Technology Data Exchange (ETDEWEB)

    Soler, E. [Departamento de Lenguajes y Ciencias de la Computacion, ETSI Informatica, Universidad de Malaga, 29071 Malaga (Spain); Ramos, J.I. [Room I-320-D, ETS Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n, 29013 Malaga (Spain)

    2005-08-01

    The thermal degradation of two-dimensional isotropic, orthotropic and anisotropic polymeric materials is studied numerically by means of a second-order accurate (in both space and time) linearly implicit finite difference formulation which results in linear algebraic equations at each time step. It is shown that, for both isotropic and orthotropic composites, the monomer mass diffusion tensor plays a role in initiating the polymerization kinetics, the formation of a polymerization kernel and the initial front propagation, whereas the later stages of the polymerization are nearly independent of the monomer mass diffusion tensor. In anisotropic polymeric composites, it has been found that the monomer mass diffusion tensor plays a paramount role in determining the initial stages of the polymerization and the subsequent propagation of the polymerization front, the direction and speed of propagation of which are found to be related to the principal directions of both the monomer mass and the heat diffusion tensors. It is also shown that the polymerization time and temperatures depend strongly on the anisotropy of the mass and heat diffusion tensors. (authors)

  14. Liquid Crystalline Dendrimers. 1. Synthesis of Five Generations of Carbosilane Liquid Crystalline Dendrimers with Terminal Cyanobiphenyl Groups

    National Research Council Canada - National Science Library

    Shibaev, V

    1998-01-01

    Using the controlled layer by layer experimental technique via reiterative sequence of chemical reactions carbosilane LC dendrimers with terminal cyanobiphenyl mesogenic groups of generations 1 - 5 were synthesized...

  15. Novel polymeric materials from triglycerides

    Science.gov (United States)

    Triglycerides are good platforms for new polymeric products that can substitute for petroleum-based materials. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a number of reactions in efforts to produce a wide range of value-added products. In this ...

  16. Novel solid state polymeric batteries

    Energy Technology Data Exchange (ETDEWEB)

    Patrick, A.; Glasse, M.; Latham, R.; Linford, R.

    1986-01-01

    AC conductivity measurements have been performed on a number of polymeric electrolytes containing Mg, Ca, Sr and Zn perchlorates and Mg and Ca thiocyanates. The electrolytes were characterized using DSC. Results are reported of preliminary tests of cells incorporating anodes of the above metals. 11 refs.

  17. Reactive surfactants in heterophase polymerization

    NARCIS (Netherlands)

    Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

    1999-01-01

    This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

  18. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

    Bennet, D.B.; Li, X.; Adams, N.W.; Kim, S.W.; Hoes, C.J.T.; Hoes, C.J.T.; Feijen, Jan

    1991-01-01

    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar

  19. Bioinspired thymine functionalized polymeric systems: from synthesis to nano applications

    OpenAIRE

    Kaur, Gagan Deep

    2017-01-01

    Nature is an abundant source of elegant examples of synthesis of materials, and as in many other areas of science, polymer chemists have been drawing on bioinspiration to create sophisticated functional materials. Thymine, one of the nucleic bases in DNA, is well known for its ability to form relatively strong hydrogen bonds as well as its propensity to undergo reversible photo-dimerization upon UV exposure. The focus of this thesis is to develop a bioinspired thymine functionalized polymeric...

  20. Glycine Polymerization on Oxide Minerals

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2017-06-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 + group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  1. Glycine Polymerization on Oxide Minerals.

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2017-06-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH 3 + group of adsorbed Gly to the nucleophilic NH 2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  2. In situ polymerization of vinyl monomers in polyester yarns

    International Nuclear Information System (INIS)

    Avny, Y.; Rebenfeld, L.; Weigmann, H.D.

    1978-01-01

    The effects of a pretreatment of polyester (PET) yarns with a strongly interacting solvent such as dimethylformamide (DMF) on vinyl monomer incorporation were investigated. When the DMF pretreatment is carried out at high temperatures (above 120 0 C), the swollen PET structure is stabilized by solvent-induced secondary crystallization. This substrate is highly suitable for the incorporation of vinyl monomers. In situ polymerization of vinyl monomers in DMF-treated PET was investigated using chemical and γ-irradiation polymerization techniques, both in the presence and in the absence of excess monomer outside the PET fibers. When polymerization was carried out in a system in which a constant supply of free radicals was available from the outside of the PET fibers, lower initiator concentrations and smaller γ-irradiation doses were necessary. These results are attributed to a low efficiency of the initiator inside the PET fiber due to mobility restrictions. Water uptake and moisture regain of PET yarns containing poly(hydroxyethyl methacrylate) and poly(acrylic acid) were also investigated. When most of the vinyl polymer was inside the PET fiber, water absorption was limited. The changes in mechanical properties of the PET yarns resulting from the DMF pretreatment were partially reversed by in situ polymerization of vinyl monomers

  3. Abortion: Strong's counterexamples fail

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2009-01-01

    This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally...

  4. Strong Langmuir turbulence

    International Nuclear Information System (INIS)

    Goldman, M.V.

    1984-01-01

    After a brief discussion of beam-excited Langmuir turbulence in the solar wind, we explain the criteria for wave-particle, three-wave and strong turbulence interactions. We then present the results of a numerical integration of the Zakharov equations, which describe the strong turbulence saturation of a weak (low-density) high energy, bump-on-tail beam instability. (author)

  5. Click polymerization for the synthesis of reduction-responsive polymeric prodrug

    Science.gov (United States)

    Zhang, Xiaojin; Wang, Hongquan; Dai, Yu

    2018-05-01

    Click polymerization is a powerful polymerization technique for the construction of new macromolecules with well-defined structures and multifaceted functionalities. Here, we synthesize reduction-responsive polymeric prodrug PEG- b-(PSS- g-MTX)- b-PEG containing disulfide bonds and pendant methotrexate (MTX) via two-step click polymerization followed by conjugating MTX to pendant hydroxyl. MTX content in polymeric prodrug is 13.5%. Polymeric prodrug is able to form polymeric micelles by self-assembly in aqueous solution. Polymeric micelles are spherical nanoparticles with tens of nanometers in size. Of note, polymeric micelles are reduction-responsive due to disulfide bonds in the backbone of PEG- b-(PSS- g-MTX)- b-PEG and could release pendant drugs in the presence of the reducing agents such as dl-dithiothreitol (DTT).

  6. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  7. Polymeric nanoparticles for optical sensing.

    Science.gov (United States)

    Canfarotta, Francesco; Whitcombe, Michael J; Piletsky, Sergey A

    2013-12-01

    Nanotechnology is a powerful tool for use in diagnostic applications. For these purposes a variety of functional nanoparticles containing fluorescent labels, gold and quantum dots at their cores have been produced, with the aim of enhanced sensitivity and multiplexing capabilities. This work will review progress in the application of polymeric nanoparticles in optical diagnostics, both for in vitro and in vivo detection, together with a discussion of their biodistribution and biocompatibility. © 2013.

  8. Polymeric Coatings for Combating Biocorrosion

    Science.gov (United States)

    Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

    2018-03-01

    Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

  9. Non-equilibrium supramolecular polymerization.

    Science.gov (United States)

    Sorrenti, Alessandro; Leira-Iglesias, Jorge; Markvoort, Albert J; de Greef, Tom F A; Hermans, Thomas M

    2017-09-18

    Supramolecular polymerization has been traditionally focused on the thermodynamic equilibrium state, where one-dimensional assemblies reside at the global minimum of the Gibbs free energy. The pathway and rate to reach the equilibrium state are irrelevant, and the resulting assemblies remain unchanged over time. In the past decade, the focus has shifted to kinetically trapped (non-dissipative non-equilibrium) structures that heavily depend on the method of preparation (i.e., pathway complexity), and where the assembly rates are of key importance. Kinetic models have greatly improved our understanding of competing pathways, and shown how to steer supramolecular polymerization in the desired direction (i.e., pathway selection). The most recent innovation in the field relies on energy or mass input that is dissipated to keep the system away from the thermodynamic equilibrium (or from other non-dissipative states). This tutorial review aims to provide the reader with a set of tools to identify different types of self-assembled states that have been explored so far. In particular, we aim to clarify the often unclear use of the term "non-equilibrium self-assembly" by subdividing systems into dissipative, and non-dissipative non-equilibrium states. Examples are given for each of the states, with a focus on non-dissipative non-equilibrium states found in one-dimensional supramolecular polymerization.

  10. Strong intrinsic motivation

    OpenAIRE

    Dessi, Roberta; Rustichini, Aldo

    2015-01-01

    A large literature in psychology, and more recently in economics, has argued that monetary rewards can reduce intrinsic motivation. We investigate whether the negative impact persists when intrinsic motivation is strong, and test this hypothesis experimentally focusing on the motivation to undertake interesting and challenging tasks, informative about individual ability. We find that this type of task can generate strong intrinsic motivation, that is impervious to the effect of monetary incen...

  11. Bitcoin Meets Strong Consistency

    OpenAIRE

    Decker, Christian; Seidel, Jochen; Wattenhofer, Roger

    2014-01-01

    The Bitcoin system only provides eventual consistency. For everyday life, the time to confirm a Bitcoin transaction is prohibitively slow. In this paper we propose a new system, built on the Bitcoin blockchain, which enables strong consistency. Our system, PeerCensus, acts as a certification authority, manages peer identities in a peer-to-peer network, and ultimately enhances Bitcoin and similar systems with strong consistency. Our extensive analysis shows that PeerCensus is in a secure state...

  12. Strong gravity and supersymmetry

    International Nuclear Information System (INIS)

    Chamseddine, Ali H.; Salam, A.; Strathdee, J.

    1977-11-01

    A supersymmetric theory is constructed for a strong f plus a weak g graviton, together with their accompanying massive gravitinos, by gaugin the gradel 0Sp(2,2,1)x 0Sp(2,2,1) structure. The mixing term between f and g fields, which makes the strong graviton massive, can be introduced through a spontaneous symmetry-breaking mechanism implemented in this note by constructing a non-linear realization of the symmetry group

  13. Uptake and metabolism of polymerized albumin by rat liver. Role of the scavenger receptor

    International Nuclear Information System (INIS)

    Wright, T.L.; Roll, F.J.; Jones, A.L.; Weisiger, R.A.

    1988-01-01

    Hepatitis B virus binds avidly to albumin polymers, which in turn may mediate viral attachment to liver cells. This hypothesis is critically dependent on prior results obtained using glutaraldehyde-polymerized human serum albumin as a model for naturally occurring albumin species. We used the perfused rat liver to characterize the uptake, cellular distribution, and metabolism of glutaraldehyde-polymerized human albumin. 125 I-glutaraldehyde-polymerized human albumin was efficiently removed from the perfusate by the liver (29% extraction). However, few autoradiographic grains were located over hepatic parenchymal cells (6%). Instead, most glutaraldehyde-polymerized human albumin appeared to be removed by endothelial (59%) or Kupffer (31%) cells. Hepatic uptake was strongly inhibited by formaldehyde-treated monomeric albumin, a known ligand of the endothelial scavenger receptor for chemically modified proteins. After uptake, most glutaraldehyde-polymerized human albumin was rapidly degraded and released into the perfusate (74% within 60 min). This process was blocked by chloroquine and leupeptin, suggesting that it involves lysosomal acid hydrolases. We conclude that glutaraldehyde-polymerized albumin is efficiently cleared and degraded by the endothelial scavenger pathway. Glutaraldehyde-polymerized albumin therefore appears to be a poor model for predicting the hepatic handling of naturally occurring albumin species bound to hepatitis B virions. Even if viral particles were to follow this pathway, few would enter parenchymal hepatocytes

  14. Effects of some polymeric additives on the cocrystallization of caffeine

    Science.gov (United States)

    Chung, Jihae; Kim, Il Won

    2011-11-01

    Effects of polymeric additives on the model cocrystallization were examined. The model cocrystal was made from caffeine and oxalic acid, and poly(ethylene glycol) (PEG), poly( L-lactide) (PLLA), poly(ɛ-caprolactone) (PCL), and poly(acrylic acid) (PAA) were the additives. The cocrystals were formed as millimeter-sized crystals without additives, and they became microcrystals with PLLA and PCL, and nanocrystals with PAA. XRD and IR revealed that the cocrystal structure was unchanged despite the strong effects of the additives on the crystal morphology, although some decrease in crystallinity was observed with PAA as confirmed by DSC. The DSC study also showed that the cocrystal melted and recrystallized to form α-caffeine upon heating. The present study verified that the polymeric additives can be utilized to modulate the size and morphology of the cocrystals without interfering the intermolecular interactions essential to the integrity of the cocrystal structures.

  15. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    International Nuclear Information System (INIS)

    Li, Peiyuan; Yang, Fang; Li, Xiangcheng; He, Chunling; Su, Wei; Chen, Jinhao; Huo, Lini; Chen, Rui; Lu, Chensheng; Liang, Lifang

    2013-01-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  16. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peiyuan, E-mail: lipearpear@163.com [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Yang, Fang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Li, Xiangcheng [School of Computer, Electronics and Information, Guangxi University, Nanning 530001 (China); He, Chunling [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Su, Wei, E-mail: suwmail@163.com [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Chen, Jinhao [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Huo, Lini; Chen, Rui; Lu, Chensheng [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Liang, Lifang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China)

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  17. Influences of Electrolytes on Soap-Free P(ST-MMA-AA) Emulsion Polymerization

    Institute of Scientific and Technical Information of China (English)

    Zeping LI; Ronglong LI; Yi DU; Chengyou KAN; Deshan LIU

    2005-01-01

    @@ 1Introduction Functional polymer microspheres are kinds of polymer particles with special structures, morphologies or functional groups[1] , and have been gained much attention because of their specific properties and their application since 1980s. Although some researches have investigated that the latex particle size and its distribution,as well as the stability of polymerization and the resultant latex were strongly influenced by introducing electrolyte into the emulsion polymerization system[2] , few of them focused on the systematic study of electrolytes on the soap-free emulsion polymerization, which is considered as a conventional approach to synthesize functional polymer microspheres with clean surfaces[2]. In this presentation, the influences of variety and dosage of electrolytes on soap-free emulsion polymerization of St, MMA and AA were studied, and a series of micron or submicron sized latex particles with narrow distribution were obtained.

  18. Characteristics of polyimide-based composite membranes fabricated by low-temperature plasma polymerization

    International Nuclear Information System (INIS)

    Dung Thi Tran; Mori, Shinsuke; Suzuki, Masaaki

    2008-01-01

    Composite membranes were prepared by the deposition of plasma-polymerized allylamine films onto a porous polyimide substrate. The relationship between the plasma conditions and the membrane characteristics was described in terms of monomer flow rate, plasma discharge power, plasma polymerization time, and so on. Scanning electron microscope (SEM) images indicate that the thickness of the plasma polymer layer increased and the membrane skin pore size decreased gradually with the increasing of plasma polymerization time. Fourier transform infrared (FTIR) spectra demonstrate the appearance of amine groups in the plasma deposited polymer and the contact angle measurements indicate that the hydrophilicity of the membrane surfaces increased significantly after plasma polymerization. The composite membranes can reject salt from sodium chloride feed solution, and membrane separation performance depends strongly on the plasma conditions applied during the preparation of the plasma deposited polymer films

  19. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  20. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu; Hsiao, Vincent; Zheng, Yue Bing; Huang, Tony Jun

    2012-01-01

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  1. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  2. Polymeric membrane materials for artificial organs.

    Science.gov (United States)

    Kawakami, Hiroyoshi

    2008-01-01

    Many polymeric materials have already been used in the field of artificial organs. However, the materials used in artificial organs are not necessarily created with the best material selectivity and materials design; therefore, the development of synthesized polymeric membrane materials for artificial organs based on well-defined designs is required. The approaches to the development of biocompatible polymeric materials fall into three categories: (1) control of physicochemical characteristics on material surfaces, (2) modification of material surfaces using biomolecules, and (3) construction of biomimetic membrane surfaces. This review will describe current issues regarding polymeric membrane materials for use in artificial organs.

  3. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  4. Strongly interacting Fermi gases

    Directory of Open Access Journals (Sweden)

    Bakr W.

    2013-08-01

    Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

  5. A strong comeback

    International Nuclear Information System (INIS)

    Marier, D.

    1992-01-01

    This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders

  6. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  7. Plasmons in strong superconductors

    International Nuclear Information System (INIS)

    Baldo, M.; Ducoin, C.

    2011-01-01

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  8. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  9. Polymeric implant of methylprednisolone for spinal injury ...

    African Journals Online (AJOL)

    Polymeric implant of methylprednisolone for spinal injury: preparation and characterization. Bo Yin, Jian-Jun Ji, Ming Yang. Abstract. Purpose: To improve the effectiveness and reduce the systemic side effects of methylprednisolone in traumatic spinal injuries, its polymeric implants were prepared using chitosan and sodium ...

  10. Strongly intensive quantities

    International Nuclear Information System (INIS)

    Gorenstein, M. I.; Gazdzicki, M.

    2011-01-01

    Analysis of fluctuations of hadron production properties in collisions of relativistic particles profits from use of measurable intensive quantities which are independent of system size variations. The first family of such quantities was proposed in 1992; another is introduced in this paper. Furthermore we present a proof of independence of volume fluctuations for quantities from both families within the framework of the grand canonical ensemble. These quantities are referred to as strongly intensive ones. Influence of conservation laws and resonance decays is also discussed.

  11. Strong-coupling approximations

    International Nuclear Information System (INIS)

    Abbott, R.B.

    1984-03-01

    Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures

  12. Nanoparticles from a controlled polymerization process

    International Nuclear Information System (INIS)

    Tirumala, V.R.; Caneba, G.T.; Dar, Y.; Wang, H.-H.; Mancini, D.C.

    2003-01-01

    Free-radical retrograde precipitation polymerization process in the past has shown excellent control characteristics over reaction rate, molecular weight, and in the entrapment of live radicals for the generation of block copolymers. The same principle has now been extended to study the reaction confinement to a nanoscale region. Nanosized polymer particles have been reported to form from block copolymers, conventional precipitation polymerization methods, or through emulsion polymerization approaches. In this work, we present a new method of generating nanosized polymer particles by polymerizing the monomer in an environment that precipitates the polymer above the lower critical solution temperature. The nanoparticles have been characterized by both tapping-mode atomic force microscopy observations and in situ synchrotron time-resolved small-angle X-ray scattering analysis. The results from both the techniques showed the formation of nanoparticles in the size range of 15-30 nm, directly from the polymerization process.

  13. Fluid Effects in Polymers and Polymeric Composites

    CERN Document Server

    Weitsman, Y Jack

    2012-01-01

    Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While...

  14. Strongly disordered superconductors

    International Nuclear Information System (INIS)

    Muttalib, K.A.

    1982-01-01

    We examine some universal effects of strong non-magnetic disorder on the electron-phonon and electron-electron interactions in a superconductor. In particular we explicitly take into account the effect of slow diffusion of electrons in a disordered medium by working in an exact impurity eigenstate representation. We find that the normal diffusion of electrons characterized by a constant diffusion coefficient does not lead to any significant correction to the electron-phonon or the effective electron-electron interactions in a superconductor. We then consider sufficiently strong disorder where Anderson localization of electrons becomes important and determine the effect of localization on the electron-electron interactions. We find that due to localization, the diffusion of electrons becomes anomalous in the sense that the diffusion coefficient becomes scale dependent. This results in an increase in the effective electron-electron interaction with increasing disorder. We propose that this provides a natural explanation for the unusual sensitivity of the transition temperature T/sub c/ of the high T/sub c/ superconductors (T/sub c/ > 10 0 K) to damage effects

  15. Strong Coupling Holography

    CERN Document Server

    Dvali, Gia

    2009-01-01

    We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...

  16. Research regarding biodegradable properties of food polymeric products under microorganism activity

    Science.gov (United States)

    Opran, Constantin; Lazar, Veronica; Fierascu, Radu Claudiu; Ditu, Lia Mara

    2018-02-01

    Aim of this research is the structural analysis by comparison of the biodegradable properties of two polymeric products made by non-biodegradable polymeric material (polypropylene TIPPLEN H949 A) and biodegradable polymeric material (ECOVIO IS 1335), under microorganism activity in order to give the best solution for the manufacture of food packaging biodegradable products. It presents the results of experimental determinations on comparative analysis of tensile strength for the two types of polymers. The sample weight variations after fungal biodegradation activity revealed that, after 3 months, there are no significant changes in polymeric substratum for non-biodegradable polymeric. The microscopically analysis showed that the fungal filaments did not strongly adhered on the non-biodegradable polymeric material, instead, both filamentous fungi strains adhered and covered the surface of the biodegradable sample with germinated filamentous conidia. The spectral analysis of polymer composition revealed that non-biodegradable polymer polypropylene spectra are identical for control and for samples that were exposed to fungal activity, suggesting that this type of sample was not degraded by the fungi strains. Instead, for biodegradable polymer sample, it was observed significant structural changes across multiple absorption bands, suggesting enzyme activity manifested mainly by Aspergillus niger strain. Structural analysis of interdisciplinary research results, lead, to achieving optimal injection molded technology emphasizing technological parameters, in order to obtain food packaging biodegradable products.

  17. Interfacial adhesion and superhydrophobicity modulated with polymeric nanopillars using integrated nanolithography

    International Nuclear Information System (INIS)

    Yang, Zong-Han; Kuo, Chiung-Wen; Chueh, Di-Yan; Tung, Yi-Chung; Chen, Peilin; Chien, Fan-Ching

    2012-01-01

    This paper reports the successful fabrication of flexible replicas with polymeric nanopillars using a process that combines nanosphere lithography, dry deep etching, soft-lithography, nanomolding and hydrophobic modification. The polymeric nanopillars with various sizes and three different periodicities have been implemented for systematic investigations on the interfacial properties on those surfaces. Such a flexible polymeric surface exhibited the maximum static contact angle of 166.8° at the nanopillars with a diameter of 60 nm, height of 710 nm and periodicity of 300 nm. The optimum aspect ratio should be less than 7 to avoid defects and collapses among those polymeric nanopillars during nanomolding. Metastable contact at the transition state indeed occurred on the parts of the intrinsic nanopillars, the experimental results of which also matched well to the classical theory of critical contact angle. Using hydrophobic modifications, metastable contacts among those polymeric nanopillars have further been eliminated. The polymeric nanopillars reported here were verified as having very strong adhesion as well as superhydrophobicity because such nanopillars made microdroplets hang firmly on the vertical surfaces of those designed replicas. (paper)

  18. Comparison of a polymeric pseudostationary phase in EKC with ODS stationary phase in RP-HPLC.

    Science.gov (United States)

    Ni, Xinjiong; Zhang, Min; Xing, Xiaoping; Cao, Yuhua; Cao, Guangqun

    2018-01-01

    Poly(stearyl methacrylate-co-methacrylic acid) (P(SMA-co-MAA)) was induced as pseudostationary phase (PSP) in electrokinetic chromatography (EKC). The n-octadecyl groups in SMA were the same as that in octadecylsilane (ODS) C18 column. Thus, the present work focused on the comparison of selectivity between polymeric PSP and ODS stationary phase (SP), and the effect of organic modifiers on the selectivity of polymeric PSP and ODS SP. 1-butanol could directly interacted with PSP as a Class I modifier, and improved both of the methylene selectivity and polar group selectivity. When the analysis times were similar, the polymeric PSP exhibited better methylene selectivity and polar group selectivity. Although the hydrophobic groups were similar, the substituted benzenes elution order was different between polymeric PSP and ODS SP. Linear solvation energy relationships (LSER) model analysis found that polymeric PSP and ODS SP exhibited two same key factors in selectivity: hydrophobic interaction and hydrogen bonding acidity. But polymeric PSP exhibited relatively strong n- and π-electrons interaction to the analytes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Modeling liquid crystal polymeric devices

    Science.gov (United States)

    Gimenez Pinto, Vianney Karina

    The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.

  20. Polymerization of lanthanide acrylonitrile complexes.

    Science.gov (United States)

    el-Mossalamy, El-Sayed H; Khalil, Ahmed A

    2002-01-01

    The molecular complexes of some lanthanides scandium (Sc3+), yttrium (Y3+), lanthanum (La3+), gadolinium (Gd3+), cerium (Ce3+) and ytterbium (Yb3) have been studies in dimethyl formamide (DMF) spectrophtometrically equilibrium constants (K), molar extintion coefficient (epsilon), energy of transition (E) and free energy (delta G*) were calculated. The polymerization of acrylonitrile has been studied and investigated in the presence of Sc3+, Y3+, La3+, Gd3+, Ce3+, and Yb3+ ions. The IR spectra of the formed AN-M (III) Br3 polymer complexes show the absence of the C identical to N band and the presence of two new bands corresponding to NH2 and OH groups. Magnetic moment values and the thermal stabilities of homopolymer and the polymer complexes were studied by means of thermogravimetric analysis and the activation energies for degradation were calculated.

  1. Polymeric materials from renewable resources

    Energy Technology Data Exchange (ETDEWEB)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; Silva, Cristina G. da; Castro, Daniele O.; Ramires, Elaine C.; Oliveira, Fernando de; Santos, Rachel P. O. [Macromolecular Materials and Lignocellulosic Fibers Group, Center for Research on Science and Technology of BioResources, Institute of Chemistry of São Carlos, University of São Paulo, CP 780, 13560-970 São Carlos, São Paulo (Brazil)

    2016-05-18

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called “biopolyethylene” (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  2. Polymeric materials from renewable resources

    Science.gov (United States)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  3. LIGO: The strong belief

    CERN Multimedia

    Antonella Del Rosso

    2016-01-01

    Twenty years of designing, building and testing a number of innovative technologies, with the strong belief that the endeavour would lead to a historic breakthrough. The Bulletin publishes an abstract of the Courier’s interview with Barry Barish, one of the founding fathers of LIGO.   The plots show the signals of gravitational waves detected by the twin LIGO observatories at Livingston, Louisiana, and Hanford, Washington. (Image: Caltech/MIT/LIGO Lab) On 11 February, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations published a historic paper in which they showed a gravitational signal emitted by the merger of two black holes. These results come after 20 years of hard work by a large collaboration of scientists operating the two LIGO observatories in the US. Barry Barish, Linde Professor of Physics, Emeritus at the California Institute of Technology and former Director of the Global Design Effort for the Internat...

  4. Strongly interacting Higgs bosons

    International Nuclear Information System (INIS)

    Appelquist, T.; Bernard, C.

    1980-01-01

    The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed

  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

    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 conduct...... a different coupling route in the polymerization, induced by the lower current density. Copyright (C) 1996 Elsevier Science Ltd....

  6. Strong-interaction nonuniversality

    International Nuclear Information System (INIS)

    Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.

    1989-01-01

    The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements

  7. John Strong (1941 - 2006)

    CERN Multimedia

    Wickens, F

    Our friend and colleague John Strong was cruelly taken from us by a brain tumour on Monday 31st July, a few days before his 65th birthday John started his career working with a group from Westfield College, under the leadership of Ted Bellamy. He obtained his PhD and spent the early part of his career on experiments at Rutherford Appleton Laboratory (RAL), but after the early 1970s his research was focussed on experiments in CERN. Over the years he made a number of notable contributions to experiments in CERN: The Omega spectrometer adopted a system John had originally developed for experiments at RAL using vidicon cameras to record the sparks in the spark chambers; He contributed to the success of NA1 and NA7, where he became heavily involved in the electronic trigger systems; He was responsible for the second level trigger system for the ALEPH detector and spent five years leading a team that designed and built the system, which ran for twelve years with only minor interventions. Following ALEPH he tur...

  8. Stirring Strongly Coupled Plasma

    CERN Document Server

    Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim

    2009-01-01

    We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...

  9. Method for forming polymerized microfluidic devices

    Science.gov (United States)

    Sommer, Gregory J.; Hatch, Anson V.; Wang, Ying-Chih; Singh, Anup K.; Renzi, Ronald F.; Claudnic, Mark R.

    2013-03-12

    Methods for making a microfluidic device according to embodiments of the present invention include defining.about.cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

  10. AZIDE-ALKYNE CLICK POLYMERIZATION: AN UPDATE

    Institute of Scientific and Technical Information of China (English)

    Hong-kun Li; Jing-zhi Sun; An-jun Qin; Ben Zhong Tang

    2012-01-01

    The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field.This review assembles an update of the advances of using azide-alkyne click polymerization to prepare functional polytriazoles (PTAs) with linear and hyperbranched structures.The Cu(Ⅰ)-mediated click polymerization furnishes 1,4-regioregular PTAs,whereas,the metal-free click polymerization of propiolates and azides produces PTAs with 1,4-regioisomer contents up to 90%.The PTAs display advanced functions,such as aggregation-induced emission,thermal stability,biocompatibility and optical nonlinearity.

  11. Unraveling the role of entropy in tuning unimolecular vs . bimolecular reaction rates: The case of olefin polymerization catalyzed by transition metals

    KAUST Repository

    Falivene, Laura; Barone, Vincenzo; Talarico, Giovanni

    2018-01-01

    by different ligand frameworks, metal, and growing polymeric chain for which experimental data are available have been selected in order to validate the main approaches to entropy calculation. Applying the “standard” protocol results in a strong disagreement

  12. Synthesis and polymerization of vinyl triazolium ionic liquids

    Science.gov (United States)

    Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof; Adzima, Brian

    2018-05-15

    Herein, we describe polymerized ionic liquids, demonstrate the synthesis of polymerized ionic liquids, and demonstrate the polymerization of triazolium monomers. One embodiment shows the polymeriazation of the triazolium monomers with bis(trifluoromethanesulfonyl)imide anions. In another embodiment we show the feasibility of copolymerizing with commodity monomers such as styrene using free radical polymerization techniques.

  13. Absence of first-order unbinding transitions of fluid and polymerized membranes

    Science.gov (United States)

    Grotehans, Stefan; Lipowsky, Reinhard

    1990-01-01

    Unbinding transitions of fluid and polymerized membranes are studied by renormalization-group (RG) methods. Two different RG schemes are used and found to give rather consistent results. The fixed-point structure of both RG's exhibits a complex behavior as a function of the decay exponent tau for the fluctuation-induced interaction of the membranes. For tau greater than tau(S2) interacting membranes can undergo first-order transitions even in the strong-fluctuation regime. These estimates for tau(S2) imply, however, that both fluid and polymerized membranes unbind in a continuous way in the absence of lateral tension.

  14. Better flocculants by radiation induced polymerization

    International Nuclear Information System (INIS)

    Laizier, J.; Gaussens, G.

    1978-01-01

    The use of radiation induced polymerization should theoritically allow to prepare better flocculants. The testings of several products prepared by such a process shows that better properties are indeed obtained: better efficiencies, lower amounts needed, better overall properties [fr

  15. Compression Behavior of High Performance Polymeric Fibers

    National Research Council Canada - National Science Library

    Kumar, Satish

    2003-01-01

    Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers...

  16. Thermal polymerization of Moringa oleifera oil

    International Nuclear Information System (INIS)

    Melo, Tania M.S.; Novack, Katia M.; Leandro, Cristiano

    2011-01-01

    It is increasingly clear both for society and the scientific community, that is necessary to find alternatives to reduce the use of polymeric materials because of their damage to the environment. One way to minimize the environmental problems related to the use of polymers is try to make them quickly degradable. In this study it was obtained a material with polymeric appearance derived from heating of the vegetable oil extracted from seeds of Moringa oleifera. The resulting product is an interesting alternative to obtain polymeric materials that may have biodegradable characteristics, coming from a renewable source and low cost. Moringa oil can be used since it has a high content of unsaturated fatty acids, and its main constituent oleic acid. All samples were characterized by FTIR, NMR and GPC. It was obtained a polymeric material, malleable, high viscosity, with some elasticity, low crystallinity and no unpleasant odor. (author)

  17. Deformation and flow of polymeric materials

    CERN Document Server

    Münstedt, Helmut

    2014-01-01

    This book describes the properties of single polymer molecules and polymeric materials and the methods how to characterize them. Molar masses, molar mass distributions and branching structure are discussed in detail. These properties are decisive for a deeper understanding of structure/properties relationships of polymeric materials. This book therefore describes and discusses them in detail. The mechanical behavior as a function of time and temperature is a key subject of the book. The authors present it on the basis of many original results they have obtained in their long research careers. They present the temperature dependence of mechanical properties of various polymeric materials in a wide temperature range: from cryogenic temperatures to the melt. Besides an extensive data collection on the transitions of various different polymeric materials, they also carefully present the physical explanations of the observed phenomena. Glass transition and melting temperatures are discussed, particularly, with the...

  18. Polymerization of sodium methacrylate induced by irradiation

    International Nuclear Information System (INIS)

    Galvan S, A.

    1998-01-01

    This work has two objectives, first: it is pretended to localize the lines of carbon links in its IR spectra, and second: following the polymerization of sodium methacrylate according to that it is irradiated with gamma rays. (Author)

  19. Reverse-osmosis membranes by plasma polymerization

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

  20. Bioadhesive polymeric platforms for transmucosal drug delivery ...

    African Journals Online (AJOL)

    Bioadhesive polymeric platforms for transmucosal drug delivery systems – a review. ... administration of certain classes of drugs, especially peptides and proteins. ... characteristics of desired bioadhesive polymers, this article then proceeds to ...

  1. Transformation kinetics of mixed polymeric substrates under ...

    African Journals Online (AJOL)

    bglucosidase and a-mannosidase were abundantly secreted in the growth medium. This research is the first report on mixed polymeric substrate biodegradation under sewer condition by A. niger, and could be considered as an open window on ...

  2. Polymerization of Polar Monomers from a Theoretical Perspective

    KAUST Repository

    Alghamdi, Miasser

    2016-10-11

    Density functional theory calculations have been used to investigate catalytic mechanism of polymer formation containing polar groups, from the synthesis of the monomer to the synthesis of the macromolecule. In the spirit of a sustainable and green chemistry, we initially focused attention on the coupling of CO2 as economically convenient and recyclable C1 source with C2H4 to form acrylate and/or butirro-lactone, two important polar monomers. In this process formation of a mettallolactone via oxidative coupling of CO2 and C2H4 is an important intermediate. Given this background, we explored in detail (chapter-3) several Ni based catalysts for CO2 coupling with C2H4 to form acrylate. In this thesis we report on the competitive reaction mechanisms (inner vs outer sphere) for the oxidative coupling of CO2 and ethylene for a set of 11 Ni-based complexes containing bisphosphine ligands. In another effort, considering incorporation of a C=C bond into a metal-oxygen-Functional-Group moiety is a challenging step in several polymerization reactions, we explored the details of this reaction (chapter4) using two different catalysts that are capable to perform this reaction in the synthesis of heterocycles. Specifically, the [Rh]-catalyzed intramolecular alkoxyacylation ([Rh] = [RhI(dppp)+] (dppp, 1,3-Bis-diphenylphosphino-propane), and the [Pd]/BPh3 intramolecular alkoxyfunctionalizations. Rest of the thesis we worked on understanding the details of the polymerization of polar monomers using organocatalysts based on N-heterocyclic carbenes (NHC) or N-heterocyclic olefins (NHO). In particular (chapter-5) we studied the polymerization of N-methyl N-carboxy- anhydrides, towards cyclic poly(N-substituted glycine)s, promoted by NHC catalysts. In good agreement with the experimental findings, we demonstrated that NHC promoted ring opening polymerization of N-Me N-Carboxyanhydrides may proceed via two different catalytic pathways. In a similar effort we studied polymerization of

  3. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  4. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  5. Polymeric Nanogels Obtained by Radiation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Ulanski, P.; Kadłubowski, A. K.; Olejnik,; Rokita, B.; Wach, R.; Rosiak, J. M. [Institute of Applied Radiation Chemistry, Technical University of Lodz, Lodz (Poland)

    2009-07-01

    Soft nanomaterials - polymeric nanogels and microgels - have made a fast and brilliant career, from an unwanted by-product of polymerization processes to an important and fashionable topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy and medicine. Together with their larger analogues - macroscopic gels, most known in the form of water-swellable hydrogels - they have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials.

  6. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions.

    Science.gov (United States)

    Coari, Kristin M; Martin, Rebecca C; Jain, Kopal; McGown, Linda B

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  7. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  8. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  9. Polymeric Nanogels Obtained by Radiation Technique

    International Nuclear Information System (INIS)

    Ulanski, P.; Kadłubowski, A.K.; Olejnik; Rokita, B.; Wach, R.; Rosiak, J.M.

    2009-01-01

    Soft nanomaterials - polymeric nanogels and microgels - have made a fast and brilliant career, from an unwanted by-product of polymerization processes to an important and fashionable topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy and medicine. Together with their larger analogues - macroscopic gels, most known in the form of water-swellable hydrogels - they have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials

  10. Stimuli-Responsive Polymeric Nanoparticles.

    Science.gov (United States)

    Liu, Xiaolin; Yang, Ying; Urban, Marek W

    2017-07-01

    There is increasing evidence that stimuli-responsive nanomaterials have become significantly critical components of modern materials design and technological developments. Recent advances in synthesis and fabrication of stimuli-responsive polymeric nanoparticles with built-in stimuli-responsive components (Part A) and surface modifications of functional nanoparticles that facilitate responsiveness (Part B) are outlined here. The synthesis and construction of stimuli-responsive spherical, core-shell, concentric, hollow, Janus, gibbous/inverse gibbous, and cocklebur morphologies are discussed in Part A, with the focus on shape, color, or size changes resulting from external stimuli. Although inorganic/metallic nanoparticles exhibit many useful properties, including thermal or electrical conductivity, catalytic activity, or magnetic properties, their assemblies and formation of higher order constructs are often enhanced by surface modifications. Section B focuses on selected surface reactions that lead to responsiveness achieved by decorating nanoparticles with stimuli-responsive polymers. Although grafting-to and grafting-from dominate these synthetic efforts, there are opportunities for developing novel synthetic approaches facilitating controllable recognition, signaling, or sequential responses. Many nanotechnologies utilize a combination of organic and inorganic phases to produce ceramic or metallic nanoparticles. One can envision the development of new properties by combining inorganic (metals, metal oxides) and organic (polymer) phases into one nanoparticle designated as "ceramers" (inorganics) and "metamers" (metallic). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Nonperturbative Renormalization Group Approach to Polymerized Membranes

    Science.gov (United States)

    Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

    2014-03-01

    Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

  12. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  13. Polymerization of N-isopropylacrylamide under magnetic levitation

    International Nuclear Information System (INIS)

    Fujiwara, Y; Katsumoto, Y; Ohishi, Y; Koyama, M; Ohno, K; Akita, M; Inoue, K; Tanimoto, Y

    2006-01-01

    A study of an effect of the magnetic levitation on polymerization of N-isopropylacrylamide at room temperature was carried out. The magnetic levitation environment, which is created by strong and upward magnetic force counterbalanced with the downward gravitational force, is multiple environment consisting of both the microgravity and the strong magnetic field which is lacking in a space vehicle orbiting around the earth. In this work, the effect was evaluated from the viewpoint of the number-average molecular weight (M n ) and the polydispersity (the index of the molecular weight distribution) of the synthesized polymer. A small extent (∼10 %) of the effect was observed on both the parameters. When the polymer was synthesized under the magnetic levitation environment, M n increased while the polydispersity decreased as compared with those of the polymer synthesized under the gravity

  14. Characterization behavior of some polymeric composite ion exchangers

    International Nuclear Information System (INIS)

    El-Zahhar, A.A; Ahdel-Aziz, H.M.; Siyam, T.

    2005-01-01

    Polymeric composite resins were prepared by template polymerization process in aqueous solution. Thermogravimetric analysis (TGA), differential thermal analysis (DTA) and The X-ray diffraction patterns (XRD) were performed to evaluate the physico chemical properties of the different polymeric composite resins. The TGA and DTA clarify high thermal stability of prepared polymeric composite resins. XRD of prepared polymeric composite shows that there is crystalline structure of some resins while other are amorphous one

  15. Self-Assembled Polymeric Micelles Based on Hyaluronic Acid-g-Poly(d,l-lactide-co-glycolide Copolymer for Tumor Targeting

    Directory of Open Access Journals (Sweden)

    Gyung Mo Son

    2014-09-01

    Full Text Available Graft copolymer composed hyaluronic acid (HA and poly(d,l-lactide-co-glycolide (PLGA (HAgLG was synthesized for antitumor targeting via CD44 receptor of tumor cells. The carboxylic end of PLGA was conjugated with hexamethylenediamine (HMDA to have amine end group in the end of chain (PLGA-amine. PLGA-amine was coupled with carboxylic acid of HA. Self-assembled polymeric micelles of HAgLG have spherical morphologies and their sizes were around 50–200 nm. Doxorubicin (DOX-incorporated polymeric micelles were prepared by dialysis procedure. DOX was released over 4 days and its release rate was accelerated by the tumoric enzyme hyaluronidase. To assess targetability of polymeric micelles, CD44-positive HepG2 cells were employed treated with fluorescein isothiocyanate (FITC-labeled polymeric micelles. HepG2 cells strongly expressed green fluorescence at the cell membrane and cytosol. However, internalization of polymeric micelles were significantly decreased when free HA was pretreated to block the CD44 receptor. Furthermore, the CD44-specific anticancer activity of HAgLG polymeric micelles was confirmed using CD44-negative CT26 cells and CD44-positive HepG2 cells. These results indicated that polymeric micelles of HaLG polymeric micelles have targetability against CD44 receptor of tumor cells. We suggest HAgLG polymeric micelles as a promising candidate for specific drug targeting.

  16. Self-Assembled Polymeric Micelles Based on Hyaluronic Acid-g-Poly(d,l-lactide-co-glycolide) Copolymer for Tumor Targeting

    Science.gov (United States)

    Son, Gyung Mo; Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Kang, Dae Hwan; Park, Su Bum; Jeong, Young-IL

    2014-01-01

    Graft copolymer composed hyaluronic acid (HA) and poly(d,l-lactide-co-glycolide) (PLGA) (HAgLG) was synthesized for antitumor targeting via CD44 receptor of tumor cells. The carboxylic end of PLGA was conjugated with hexamethylenediamine (HMDA) to have amine end group in the end of chain (PLGA-amine). PLGA-amine was coupled with carboxylic acid of HA. Self-assembled polymeric micelles of HAgLG have spherical morphologies and their sizes were around 50–200 nm. Doxorubicin (DOX)-incorporated polymeric micelles were prepared by dialysis procedure. DOX was released over 4 days and its release rate was accelerated by the tumoric enzyme hyaluronidase. To assess targetability of polymeric micelles, CD44-positive HepG2 cells were employed treated with fluorescein isothiocyanate (FITC)-labeled polymeric micelles. HepG2 cells strongly expressed green fluorescence at the cell membrane and cytosol. However, internalization of polymeric micelles were significantly decreased when free HA was pretreated to block the CD44 receptor. Furthermore, the CD44-specific anticancer activity of HAgLG polymeric micelles was confirmed using CD44-negative CT26 cells and CD44-positive HepG2 cells. These results indicated that polymeric micelles of HaLG polymeric micelles have targetability against CD44 receptor of tumor cells. We suggest HAgLG polymeric micelles as a promising candidate for specific drug targeting. PMID:25216338

  17. Acrylate intercalation and in situ polymerization in iron-, cobalt-, or manganese-substituted nickel hydroxides.

    Science.gov (United States)

    Vaysse, C; Guerlou-Demourgues, L; Duguet, E; Delmas, C

    2003-07-28

    A chimie douce route based on successive redox and exchange reactions has allowed us to prepare new hybrid organic-inorganic materials, composed of polyacrylate macromolecules intercalated into layered double hydroxides (LDHs), deriving from Ni(OH)(2). Monomer intercalation and in situ polymerization mechanisms have appeared to be strongly dependent upon the nature of the substituting cation in the slabs. In the case of iron-based LDHs, a phase containing acrylate monomeric intercalates has been isolated and identified by X-ray diffraction and infrared spectroscopy. Second, interslab free-radical polymerization of acrylate anions has been successfully initiated using potassium persulfate. In cobalt- or manganese-based LDHs, one-step polymerization has been observed, leading directly to a material containing polyacrylate intercalate.

  18. Radiation induced solid-state polymerization of long-chain acrylates containing fluorocarbon chain

    International Nuclear Information System (INIS)

    Shibasaki, Y.; Zhu, Zhi-Qin

    1995-01-01

    γ-Ray irradiation post-polymerizations of long-chain acrylates containing fluorocarbon chain, H(CF 2 ) 10 CH 2 OCOCH=CH 2 and H(CF 2 ) 8 CH 2 OCOCH=CH 2 , were investigated and also the structures and thermal properties of comb-like polymers obtained were studied. It was found that these monomers exhibited very high polymerizability at wide temperature ranges around the melting points. Because the fluorocarbon chains are less flexible and thicker than the hydrocarbon chains, it can be expected that the aggregation force among the monomer molecules is strong and the conformational freedom of functional group for polymerization is large. According to the DSC and the X-ray diffraction measurements of the comb-like polymers obtained, the fluorocarbon chains are aggregated in a mode of hexagonal packing in the lamellar crystals. This situation can be considered as an optimum condition for the γ-ray irradiation post-polymerization. (author)

  19. Positron Annihilation Spectroscopy as a Novel Interfacial Probe for Thin Polymeric Films and Nano-Composites

    Science.gov (United States)

    Awad, Somia; Chen, Hongmin; Maina, Grace; Lee, L. James; Gu, Xiaohong; Jean, Y. C.

    2010-03-01

    Positron annihilation spectroscopy (PAS) has been developed as a novel probe to characterize the sub-nanometer defect, free volume, profile from the surface, interfaces, and to the bulk in polymeric materials when a variable mono-energy slow positron beam is used. Free-volume hole sizes, fractions, and distributions are measurable as a function of depth at the high precision. PAS has been successfully used to study the interfacial properties of polymeric nanocomposites at different chemical bonding. In nano-scale thin polymeric films, such as in PS/SiO2, and PU/ZnO, significant variations of Tg as a function of depth and of wt% oxide are observed. Variations of Tg are dependent on strong or weak interactions between polymers and nano-scale oxides surfaces.

  20. Oxygen transport as a structure probe for heterogeneous polymeric systems

    Science.gov (United States)

    Hu, Yushan

    Although permeability of small molecules is often measured as an important performance property, deeper analysis of the transport characteristics provides insight into polymer structure, especially if used in combination with other characterization techniques. Transport of small gas molecules senses the permeable amorphous structure and probes the nature of free volume. This work focuses on oxygen transport, supplemented with other methods of physical analysis, as a probe for: (1) the nature of free volume and crystalline morphology in the crystallized glassy state, (2) the nature of free volume and hierarchical structure in liquid crystalline polymers, and (3) the role of dispersed polyamide phase geometry on oxygen barrier properties of poly(ethylene terephthalate) (PET)/polyamide blends. In the first part, the improvement in oxygen-barrier properties of glassy polyesters by crystallization was examined. Examples included poly(ethylene naphthalate) (PEN), and a copolymer based on PET in which 55 mol% terephthalate was replaced with 4,4'-bibenzoate. Explanation of the unexpectedly high solubility of crystallized PEN required a two-phase transport model consisting of an impermeable crystalline phase of constant density and a permeable amorphous phase of variable density. The resulting relationship between oxygen solubility and amorphous phase density was consistent with free volume concepts of gas sorption. In the second part, oxygen barrier properties of liquid crystalline (LC) polyesters based on poly(diethylene glycol 4,4'-bibenzoate) (PDEGBB) were studied. This study extended the 2-phase transport model for oxygen transport of non-LC crystalline polymers to a smectic LCP. It was possible to systematically vary the solid state structure of (PDEGBB) from LC glass to crystallized LC glass. The results were consistent with a liquid crystalline state intermediate between the permeable amorphous glass and the impermeable 3-dimensional crystal. In this interpretation

  1. Genotoxic evaluation of polymeric nanoparticles

    Directory of Open Access Journals (Sweden)

    Tamara Iglesias Alonso

    2015-06-01

    Full Text Available An important strategy for optimizing the therapeutic efficacy of many conventional drugs is the development of polymeric nanoparticles (NPs, as it may expand their activities, reduce their toxicity, increase their bioactivity and improve biodistribution. The main objective of this study was to evaluate the genotoxicity of 8 different poly (anhydride NPs designed for the oral administration of therapeutic compounds by using the comet assay in combination with the enzyme formamidopypiridine DNA-glycosylase (FPG. Furthermore, the mitogen capacity of the NPs was evaluated by the proliferation assay. All NPs were tested at four concentrations (0, 0.5, 1 and 2 mg/mL in Caco-2 cells after 3 hours of treatment while selected NPs were also tested after 24 h. The comet assay was performed immediately after the treatment and cell proliferation was assessed by counting the treated cells after their incubation at 37 °C for 48h. Cells treated with 1 µM of the photosensitizer Ro 19-8022 plus 5 min of light, as well as cells treated with 100 µM H2O2 were included as positive controls in all the experiments. All NPs studied did not result in any increase in the frequency of strand breaks or alkali-labile sites in Caco-2 cells but they induced a slight concentration-dependent increase in net FPG sensitive sites (oxidized and/or alkylated bases. Furthermore, treated cells did not show changes in levels of proliferation in comparison with the negative control.

  2. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

    Science.gov (United States)

    Kitadai, Norio

    2017-03-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg 2+ ) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu 2+ ) are therefore not beneficial places for peptide bond formation on the primitive

  3. Fault Diagnosis Method of Polymerization Kettle Equipment Based on Rough Sets and BP Neural Network

    Directory of Open Access Journals (Sweden)

    Shu-zhi Gao

    2013-01-01

    Full Text Available Polyvinyl chloride (PVC polymerizing production process is a typical complex controlled object, with complexity features, such as nonlinear, multivariable, strong coupling, and large time-delay. Aiming at the real-time fault diagnosis and optimized monitoring requirements of the large-scale key polymerization equipment of PVC production process, a real-time fault diagnosis strategy is proposed based on rough sets theory with the improved discernibility matrix and BP neural networks. The improved discernibility matrix is adopted to reduct the attributes of rough sets in order to decrease the input dimensionality of fault characteristics effectively. Levenberg-Marquardt BP neural network is trained to diagnose the polymerize faults according to the reducted decision table, which realizes the nonlinear mapping from fault symptom set to polymerize fault set. Simulation experiments are carried out combining with the industry history datum to show the effectiveness of the proposed rough set neural networks fault diagnosis method. The proposed strategy greatly increased the accuracy rate and efficiency of the polymerization fault diagnosis system.

  4. Highly efficient and selective pressure-assisted photon-induced polymerization of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Jiwen [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Song, Yang, E-mail: yang.song@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7 (Canada)

    2016-06-07

    The polymerization process of condensed styrene to produce polystyrene as an industrially important polymeric material was investigated using a novel approach by combining external compression with ultraviolet radiation. The reaction evolution was monitored as a function of time and the reaction products were characterized by in situ Fourier transform infrared spectroscopy. By optimizing the loading pressures, we observed highly efficient and selective production of polystyrene of different tacticities. Specifically, at relatively low loading pressures, infrared spectra suggest that styrene monomers transform to amorphous atactic polystyrene (APS) with minor crystalline isotactic polystyrene. In contrast, APS was found to be the sole product when polymerization occurs at relatively higher loading pressures. The time-dependent reaction profiles allow the examination of the polymerization kinetics by analyzing the rate constant and activation volume as a function of pressure. As a result, an optimized pressure condition, which allows a barrierless reaction to proceed, was identified and attributed to the very desirable reaction yield and kinetics. Finally, the photoinitiated reaction mechanism and the growth geometry of the polymer chains were investigated from the energy diagram of styrene and by the topology analysis of the crystal styrene. This study shows strong promise to produce functional polymeric materials in a highly efficient and controlled manner.

  5. Survey and research on precision polymerization polymeric materials; Seimitsu jugo kobunshi zairyo ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Survey and research on the precision control of primary structure of polymeric materials and the precision evaluation technology have been conducted to develop advanced polymeric materials. It is proposed that the three basic processes of polymer synthesis, i.e., addition, condensation, and biomimesis, in forming the precision polymerization skeleton are to be covered through a centralized joint research effort with participation of industry, academia, and the government institute and under the leadership of researchers from academic institutions as the team leaders. For the study of technology trends, international conferences held in UK, Germany, and Hawaii are introduced, and domestic meetings, i.e., Annual Polymer Congress and Polymer Conference, are summarized. In addition, Precision Polymerization Forum and International Workshop on Precision Polymerization were held. The basic studies include a quantum-chemical elucidation of the elementary process in polymerization reaction, time-resolved analysis of polymerization process and polymer properties, synthesis of polymers with controlled microstructures by coordination polymerization using metal complexes, synthesis of polymer with controlled microstructures by precision polycondensation, molecular recognition in catalyst-reaction site, and synthesis of imprinting polymers. 246 refs., 117 figs., 14 tabs.

  6. Polymerization in situ by means of radiation gamma for the production of conducting polymeric composites

    International Nuclear Information System (INIS)

    Poblete Pulgar, Victor; Pilleux Cepeda, Mauricio; Fuenzalida Escobar, Victor; Alvarez Vargas, Mariela

    2002-01-01

    The nanocomposites synthesis of copper-methyl metacritate is made using copper spheres from 80 to 120 diameter nm, suspended in a methyl metacrilato (MMA) matrix, for different concentrations (5% to 30% of copper-v/v). The polymerization is carried out by means of gamma radiation, with 16 kGy dose applied 'in situ'. A high homogenous samples were obtained. The morphology and formation of the composite was studied by means of scanning electronic microscopy (SEM). The observed electric resistance is analyzed in function of the distance among electric contacts, meeting a strong dependence of the resistance with the homogeneous distribution of the metal in the composite. The obtained specific resistivities, in function of the concentration of the conductive metal, they are in the order of 42 Ωm for 10% v/v, being this critical concentration, the percolation threshold of the system. The obtained results show a material that is able to conserve principally the mechanical properties of the polymer and the electric properties of the conductive metal (author)

  7. PREFACE: 9th National Symposium on Polymeric Materials (NSPM 2009)

    Science.gov (United States)

    Ali, Aidy; Salit, Sapuan

    2010-07-01

    NSPM 2009 is the formal proceedings of the 9th National Symposium on Polymeric Materials held in Residence Hotel Uniten Bangi on 14-16 December 2009. It is also organised with The Plastics and Rubber Institute Malaysia PRIM. The symposium proceedings consists of 94 papers covering a large number of issues on experimental and analytical studies of polymeric materials. The objectives of the symposium are to review the state-of-the art, present and latest findings and exchange ideas among engineers, researchers and practitioners involved in this field. We strongly hope the outcomes of this symposium will stimulate and enhanced the progress of experimental and analytical studies on polymeric materials as well as contribute to the fundamental understanding in related fields. After careful refereeing of all manuscripts, 15 papers were selected for publications in this issue. Another 20 papers were selected for publication in Pertanika Journal of Science and Technology (PJST). The content of the material and its rapid dissemination was considered to be more important than its form. We are grateful to all the authors for their papers and presentations in this symposium. They are also the ones who help make this symposium possible through their hard work in the preparation of the manuscripts. We would also like to offer our sincere thanks to all the invited speakers who came to share their knowledge with us. We would also like to acknowledge the untiring efforts of the reviewers, research assistants and students in meeting deadlines and for their patience and perseverance. We are indeed honoured to associate this event with Department of Mechanical and Manufacturing, and Faculty of Engineering, Universiti Putra Malaysia. Finally, we appreciate the sponsor support provided by Faculty of Engineering, The Plastics and Rubber Institute Malaysia (PRIM) and PETRONAS Malaysia. Thank you all. Editors: Aidy Ali and S M Sapuan

  8. Polymerization of N-(fluoro phenyl) maleimides

    International Nuclear Information System (INIS)

    Barrales-Rienda, J.M.; Ramos, J.G.; Chaves, M.S.

    1979-01-01

    Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by azobisisobutyronitrile in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N-(fluoro phenyl) maleimide]s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. 6 figures, 8 tables

  9. Electrospun polymeric nanofibers for transdermal drug delivery

    Directory of Open Access Journals (Sweden)

    Mahya Rahmani

    2017-04-01

    Full Text Available Conventional transdermal drug delivery systems (TDDS have been designed for drug delivery through the skin. These systems use the permeability property of stratum corneum, the outermost surface layer of the skin. Applying polymeric micro and nanofibers in drug delivery has recently attracted great attention and the electrospinning technique is the preferred method for polymeric micro-nanofibers fabrication with a great potential for drug delivery. More studies in the field of nanofibers containing drug are divided two categories: first, preparation and characterization of nanofibers containing drug and second, investigation of their therapeutic applications. Drugs used in electrospun nanofibers can be categorized into three main groups, including antibiotics and antimicrobial agents, anti-inflammatory agents and vitamins with therapeutic applications. In this paper, we review the application of electrospun polymeric scaffolds in TDDS and also introduce several pharmaceutical and therapeutic agents which have been used in polymer nanofibrous patches.

  10. Biomimetic polymeric membranes for water treatment

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto

    This project is about the interplay of the three major components of aquaporin based biomimetic polymeric membranes (ABPMs): Aquaporins (AQPs), amphiphilic block copolymers, serving as a vesicular matrix for the hydrophobic AQP exterior (proteopolymersomes) and a polymeric membrane as embedment....... The interplay of proteopolymersomes and polymeric mesh support (in this case polyethersulfone, PES) was examined via integration of proteopolymersomes in an active layer (AL) formed by interfacial polymerisation between a linker molecule in aqueous phase and another in organic phase on top of the PES....... The resulting thin-film composite (TFC) membrane was analyzed via cross-flow forward osmosis (FO), scanning electron microscopy (SEM), fourier-transformed infrared spectroscopy (FTIR), as well as in the non-supported form over FTIR and a specialized microfluidic visualization approach. Where no clear dierences...

  11. Cross-linking of polymeric materials

    International Nuclear Information System (INIS)

    Bloom, L.I.; Du Plessis, T.A.; Meij, G.O.

    1991-01-01

    The invention provides a method of producing a cured polymeric artifact from a polymeric thermoplastic starting material, the material of the artifact having reduced thermoplasticity relative to the starting material and exhibiting an enhanced degree of cross-linking relative to the starting material. The method includes subjecting a polymeric thermoplastic starting material, which is capable of being cross-linked by irradiation, to sufficient irradiation partially to cross-linked the starting material to produce a thermoplastic partially cross-linked intermediate material. The thermoplasticity of the intermediate material is then reduced by heating it to raise its melting point. The invention also provides a method of making a partially cross-linked feedstocks and a master batch for use in making such artifacts

  12. Laser microstructuring for fabricating superhydrophobic polymeric surfaces

    Science.gov (United States)

    Cardoso, M. R.; Tribuzi, V.; Balogh, D. T.; Misoguti, L.; Mendonça, C. R.

    2011-02-01

    In this paper we show the fabrication of hydrophobic polymeric surfaces through laser microstructuring. By using 70-ps pulses from a Q-switched and mode-locked Nd:YAG laser at 532 nm, we were able to produce grooves with different width and separation, resulting in square-shaped pillar patterns. We investigate the dependence of the morphology on the surface static contact angle for water, showing that it is in agreement with the Cassie-Baxter model. We demonstrate the fabrication of a superhydrophobic polymeric surface, presenting a water contact angle of 157°. The surface structuring method presented here seems to be an interesting option to control the wetting properties of polymeric surfaces.

  13. In situ polymerization process of polypyrrole ultrathin films

    International Nuclear Information System (INIS)

    Onoda, Mitsuyoshi; Tada, Kazuya; Shinkuma, Akira

    2006-01-01

    A novel thin film processing technique has been developed for the fabrication of ultrathin films of conducting polymers with molecular-level control over thickness and multilayer architecture. This new self-assembly process opens up vast possibilities in applications which require large area, ultrathin films of conducting polymers and more importantly in applications that can take advantage of the unique interactions achievable in the complex, supermolecular architectures of multilayer films. In in situ polymerized polypyrrole (PPy), the deposition process strongly depends on the nature of the substrate surface. That is, for a surface that is negatively charged, there is a linear correspondence between dipping time and the amount of PPy deposited on the substrate. However, in the case of a positively charged surface, there is an apparent rest period of approximately 10-20 min, during which no PPy is deposited. From optical absorption spectroscopy and photoelectron emission studies etc., it became clear that oligomers of pyrrole were adsorbed on the positively charged surface during the rest period, as a result the polymerization reaction of PPy could proceed

  14. molecular weight control of a batch suspension polymerization reactor

    International Nuclear Information System (INIS)

    Shahrokhi, M.; Fanaei, M. A.

    2002-01-01

    This paper concerns molecular weight control of a batch polymerization reactor where suspension polymerization of methyl methylacrylate (MMA) takes place. For this purpose, a cascade control structure with two control loops has been selected. The slave loop is used for temperature control using on-line temperature measurements, and the master loop controls the average molecular weights based on its estimated values. Two different control algorithms namely proportional-integral (PI) controller and globally linearizing controller (GLC) have been used for temperature control. An estimator, which has the structure of an extended Kalman filter(EKF), is used for estimating monomer conversion and average molecular weights of polymer using reactor temperature measurements. The performance of proposed control algorithm is evaluated through simulation and experimental studies. The results indicate that a constant average molecular weight cannot be achieved in case of strong gel effect. However, the polydispersity of product will be lower in comparison to isothermal operation. It is also shown that in case of mo dek mismatch, the performance of cascade control is superior compared to the case where only reactor temperature is controlled based on desired temperature trajectory obtained through cascade strategy

  15. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric materialis described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney......-Rivlin model show a monotone increasingpressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...... inflated. Membranesdescribed by these models develop a local thinning of the membrane which may lead to bursting in finite time....

  16. Polymeric materials obtained by electron beam irradiation

    International Nuclear Information System (INIS)

    Dragusin, M.; Moraru, R.; Martin, D.; Radoiu, M.; Marghitu, S.; Oproiu, C.

    1995-01-01

    Research activities in the field of electron beam irradiation of monomer aqueous solution to produce polymeric materials used for waste waters treatment, agriculture and medicine are presented. The technologies and special features of these polymeric materials are also described. The influence of the chemical composition of the solution to ba irradiated, absorbed dose level and absorbed dose rate level are discussed. Two kinds of polyelectrolytes, PA and PV types and three kinds of hydrogels, pAAm, pAAmNa and pNaAc types, the production of which was first developed with IETI-10000 Co-60 source and then adapted to the linacs built in Accelerator Laboratory, are described. (author)

  17. Mechanism and kinetics of addition polymerizations

    CERN Document Server

    Kucera, M

    1991-01-01

    This volume presents an up-to-date survey of knowledge concerning addition type polymerizations. It contains nine chapters, each of which covers a particular basic term. Whenever necessary, the phenomena are discussed from the viewpoint of both stationary and non-stationary state of radical, ionic (i.e. anionic and cationic) and coordination polymerization. Special attention has been paid to the propagation process. It provides not only a general overview but also information on important special cases (theoretical conditions of propagation, influence of external factors, controlled propagatio

  18. Polymeric matrix materials for infrared metamaterials

    Science.gov (United States)

    Dirk, Shawn M; Rasberry, Roger D; Rahimian, Kamyar

    2014-04-22

    A polymeric matrix material exhibits low loss at optical frequencies and facilitates the fabrication of all-dielectric metamaterials. The low-loss polymeric matrix material can be synthesized by providing an unsaturated polymer, comprising double or triple bonds; partially hydrogenating the unsaturated polymer; depositing a film of the partially hydrogenated polymer and a crosslinker on a substrate; and photopatterning the film by exposing the film to ultraviolet light through a patterning mask, thereby cross-linking at least some of the remaining unsaturated groups of the partially hydrogenated polymer in the exposed portions.

  19. Curing mechanism of flexible aqueous polymeric coatings.

    Science.gov (United States)

    Irfan, Muhammad; Ahmed, Abid Riaz; Kolter, Karl; Bodmeier, Roland; Dashevskiy, Andriy

    2017-06-01

    The objective of this study was to explain curing phenomena for pellets coated with a flexible polymeric coating based on poly(vinyl acetate) (Kollicoat® SR 30D) with regard to the effect of starter cores, thickness of drug layer, adhesion of coating to drug-layered-cores as well as coating properties. In addition, appropriate approaches to eliminate the curing effect were identified. Sugar or MCC cores were layered with the model drugs carbamazepine, theophylline, propranolol HCl, tramadol HCl and metoprolol HCl using HPMC (5 or 25% w/w, based on drug) as a binder. Drug-layered pellets were coated with Kollicoat® SR 30D in a fluidized bed coater using TEC (10% w/w) as plasticizer and talc (35-100% w/w) as anti-tacking agent. Drug release, pellet properties (morphology, water uptake-weight loss and osmolality) and adhesion of the coating to the drug layer were investigated as a function of curing at 60°C or 60°C/75% RH for 24h. The film formation of the aqueous dispersion of Kollicoat® SR 30D was complete, and therefore, a strong curing effect (decrease in drug release) at elevated temperature and humidity (60°C/75% RH) could not be explained by the well-known hydroplasticization and the further gradual coalescence of the colloidal polymer particles. According to the provided mechanistic explanation, the observed curing effect was associated with (1) high flexibility of coating, (2) adhesion between coating and drug layer, (3) water retaining properties of the drug layer, and (4) osmotically active cores. Unwanted curing effects could be minimized/eliminated by the addition of talc or/and pore-forming water soluble polymers in the coating, increasing binder amount or applying an intermediate coating, by increasing the thickness of drug layer or using non-osmotic cores. A new insight into curing phenomena mainly associated with the adhesion between drug layer and coating was provided. Appropriate approaches to avoid unwanted curing effect were identified

  20. Electric properties of polymeric nanocomposites filler with copper particles polymerized in situ by means of gamma radiation

    International Nuclear Information System (INIS)

    Poblete, V.H; Alvarez, M; Pilleux, M.E

    2002-01-01

    Different concentrations of copper metallic nanoparticles (80-120 diameter nm) were distributed in a methyl metacrilate (MMA) matrix. The polymerization of the mixture was carried out by means of gamma radiation using 16 kGy (2 kGy/hour) dose, applied in situ, obtaining an homogeneous and resistant mechanically samples. For comparison the same experience was carried out using 3,25-4,5 um of copper particles diameter. The morphology and the composite formation was studied by means of X-ray diffraction and scanning electronic microscopy for the different concentrations of the conductive metal into the polymeric matrix (5-30 vol. copper%). The electric resistance observed was analyzed in function of the distance between electric contacts. The strong lineal dependence show a homogeneous distribution of the metal in the composite. The specific resistivities obtained in function of the concentration of the conductive metal is in the range from the 12 to 42 Ωm for 10 vol.% concentrations. This results is in agreement with the threshold limit of the system. Also, the dependence of the resistivity with the particle size is showed (author)

  1. Immobilization of biocatalysts for enzymatic polymerizations : Possibilities, advantages, applications

    NARCIS (Netherlands)

    Miletic, Nemanja; Nastasovic, Aleksandra; Loos, Katja; Miletić, Nemanja; Nastasović, Aleksandra

    Biotechnology also holds tremendous opportunities for realizing functional polymeric materials. Biocatalytic pathways to polymeric materials are an emerging research area with not only enormous scientific and technological promise, but also a tremendous impact on environmental issues. Many of the

  2. Polymerization Initiated at the Sidewalls of Carbon Nanotubes

    Science.gov (United States)

    Tour, James M.; Hudson, Jared L.

    2011-01-01

    A process has been developed for growing polymer chains via anionic, cationic, or radical polymerization from the side walls of functionalized carbon nanotubes, which will facilitate greater dispersion in polymer matrices, and will greatly enhance reinforcement ability in polymeric material.

  3. Interfacial Polymerization of Polyaniline Nanofibers Grafted to Au Surfaces

    National Research Council Canada - National Science Library

    Sawall, D

    2004-01-01

    .... The in-situ polymerization technique of these PANI nanofibers in the presence of sulfonated polystyrene allowed for the growth of PANI 2-D nanostructures embedded in the polymerized sulfonated host...

  4. Influence of semisynthetic modification of the scaffold of a contact domain of HbS on polymerization: role of flexible surface topology in polymerization inhibition.

    Science.gov (United States)

    Sonati, Srinivasulu; Bhutoria, Savita; Prabhakaran, Muthuchidambaran; Acharya, Seetharama A

    2018-02-01

    A new variant of HbS, HbS-Einstein with a deletion of segment α 23-26 in the B-helix, has been assembled by semisynthetic approach. B-helix of the α chain of cis αβ-dimer of HbS plays dominant role in the quinary interactions of deoxy HbS dimer. This B-helix is the primary scaffold that provides the orientation for the side chains of contact residues of this intermolecular contact domain. The design of HbS-Einstein has been undertaken to map the influence of perturbation of molecular surface topology and the flexibility of surface residues in the polymerization. The internal deletion exerts a strong inhibitory influence on Val-6 (β)-dependent polymerization, comparable to single contact site mutations and not for complete neutralization of Val-6(β)-dependent polymerization. The scaffold modification in cis-dimer is inhibitory, and is without any effect when present on the trans dimer. The flexibility changes in the surface topology in the region of scaffold modification apparently counteracts the intrinsic polymerization potential of the molecule. The inhibition is close to that of Le Lamentin mutation [His-20 (α) → Gln] wherein a mutation engineered without much change in flexibility of the contact domain. Interestingly, the chimeric HbS with swine-human chimeric α chain with multiple non-conservative mutations completely inhibits the Val-6(β)-dependent polymerization. The deformabilities of surface topology of chimeric HbS are comparable to HbS in spite of the multiple contact site mutations in the α-chain. We conclude that the design of antisickling Hbs for gene therapy of sickle cell disease should involve multiple mutations of intermolecular contact sites.

  5. Quantum electrodynamics of strong fields

    International Nuclear Information System (INIS)

    Greiner, W.

    1983-01-01

    Quantum Electrodynamics of Strong Fields provides a broad survey of the theoretical and experimental work accomplished, presenting papers by a group of international researchers who have made significant contributions to this developing area. Exploring the quantum theory of strong fields, the volume focuses on the phase transition to a charged vacuum in strong electric fields. The contributors also discuss such related topics as QED at short distances, precision tests of QED, nonperturbative QCD and confinement, pion condensation, and strong gravitational fields In addition, the volume features a historical paper on the roots of quantum field theory in the history of quantum physics by noted researcher Friedrich Hund

  6. Instabilities in strongly coupled plasmas

    CERN Document Server

    Kalman, G J

    2003-01-01

    The conventional Vlasov treatment of beam-plasma instabilities is inappropriate when the plasma is strongly coupled. In the strongly coupled liquid state, the strong correlations between the dust grains fundamentally affect the conditions for instability. In the crystalline state, the inherent anisotropy couples the longitudinal and transverse polarizations, and results in unstable excitations in both polarizations. We summarize analyses of resonant and non-resonant, as well as resistive instabilities. We consider both ion-dust streaming and dust beam-plasma instabilities. Strong coupling, in general, leads to an enhancement of the growth rates. In the crystalline phase, a resonant transverse instability can be excited.

  7. Vibrating polymeric microsieves: Antifouling strategies for microfiltration

    NARCIS (Netherlands)

    Girones nogue, Miriam; Akbarsyah, Imam J.; Bolhuis-Versteeg, Lydia A.M.; Lammertink, Rob G.H.; Wessling, Matthias

    2006-01-01

    Constant flux performance in time is achieved with polyethersulfone (PES) polymeric microsieves when filtering protein solutions, skimmed milk and white beer in combination with backpulsing. Such microsieves are fabricated by phase separation micromolding (PSμM) and possess pores around 2 μm. The

  8. Inflation and Failure of Polymeric Membranes

    DEFF Research Database (Denmark)

    Hassager, Ole; Neergaard, Jesper

    2000-01-01

    We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere...... is found to stabilize the inflated polymer membrane....

  9. Gamma Radiation-Induced Template Polymerization Technique

    International Nuclear Information System (INIS)

    Siyam, T.

    2005-01-01

    Gamma radiation induced copolymerization of acrylamide sodiumacrylate (AM-AANa) in the presence and absence of the polymer additive was studied at low monomer concentration(1.4M/l). The results showed that the exponents of the dose rate for the polymerization rate was found to be 1.3 and 1.4 in the absence and in the presence of the polymer additive respectively. The molecular weight of the formed polymer increased by addition of the polymer to the system. In the presence of the polymer the comonomers polymerize on the added polymer. In the absence of the added polymer the comonomers polymerize according to the copolymerization process at the initial stage of the copolymerization. While at high conversion the residual comonomers polymerize on the formed macromolecular chains of the produced polymer. These studies showed that the copolymerization in the presence of added polymer is completely template copolymerization while in the absence of the polymer the copolymerization process is only template process with a high conversion

  10. Polymerization of epoxidized triglycerides with fluorosulfonic acid

    Science.gov (United States)

    The use of triglycerides as agri-based renewable raw materials for the development of new products is highly desirable in view of uncertain future petroleum prices. A new method of polymerizing epoxidized soybean oil has been devised with the use of fluorosulfonic acid. Depending on the reaction con...

  11. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...

  12. Polymeric additive performance in closed whitewater systems

    Science.gov (United States)

    T. H. Wegner

    1984-01-01

    “With more stringent requirements on discharge water quality and with escalating water treatment costs, water recycling within the paper mill is of growing importance. A serious problem resulting from more white-water recycling is reduced drainage and fiber or fines retention because of diminished polymeric additive performance. To provide better insight for overcoming...

  13. Latent tracks in polymeric etched track detectors

    International Nuclear Information System (INIS)

    Yamauchi, Tomoya

    2013-01-01

    Track registration properties in polymeric track detectors, including Poly(allyl diglycol carbonate), Bispenol A polycarbonate, Poly(ethylen terephtarate), and Polyimide, have been investigated by means of Fourie transform Infararede FT-IR spectrometry. Chemical criterion on the track formation threshold has been proposes, in stead of the conventional physical track registration models. (author)

  14. Bioactive Polymeric Materials for Tissue Repair

    Directory of Open Access Journals (Sweden)

    Diane R. Bienek

    2017-01-01

    Full Text Available Bioactive polymeric materials based on calcium phosphates have tremendous appeal for hard tissue repair because of their well-documented biocompatibility. Amorphous calcium phosphate (ACP-based ones additionally protect against unwanted demineralization and actively support regeneration of hard tissue minerals. Our group has been investigating the structure/composition/property relationships of ACP polymeric composites for the last two decades. Here, we present ACP’s dispersion in a polymer matrix and the fine-tuning of the resin affects the physicochemical, mechanical, and biological properties of ACP polymeric composites. These studies illustrate how the filler/resin interface and monomer/polymer molecular structure affect the material’s critical properties, such as ion release and mechanical strength. We also present evidence of the remineralization efficacy of ACP composites when exposed to accelerated acidic challenges representative of oral environment conditions. The utility of ACP has recently been extended to include airbrushing as a platform technology for fabrication of nanofiber scaffolds. These studies, focused on assessing the feasibility of incorporating ACP into various polymer fibers, also included the release kinetics of bioactive calcium and phosphate ions from nanofibers and evaluate the biorelevance of the polymeric ACP fiber networks. We also discuss the potential for future integration of the existing ACP scaffolds into therapeutic delivery systems used in the precision medicine field.

  15. Hyaluronan polymeric micelles for topical drug delivery

    Czech Academy of Sciences Publication Activity Database

    Šmejkalová, D.; Muthný, T.; Nešporová, K.; Hermannová, M.; Achbergerová, E.; Huerta-Angelesa, G.; Marek Svoboda, M.; Čepa, M.; Machalová, V.; Luptáková, Dominika; Velebný, V.

    2017-01-01

    Roč. 156, JAN 20 (2017), s. 86-96 ISSN 0144-8617 Institutional support: RVO:61388971 Keywords : Skin penetration * Polymeric micelle * Hyaluronan Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.811, year: 2016

  16. The Morphology of Emulsion Polymerized Latex Particles

    Science.gov (United States)

    Wignall, G. D.; Ramakrishnan, V. R.; Linne, M. A.; Klein, A.; Sperling, L. H.; Wai, M. P.; Gelman, R. A.; Fatica, M. G.; Hoerl, R. H.; Fisher, L. W.

    1987-11-01

    Under monomer starved feed conditions, emulsion polymerization of perdeuterated methyl methacrylate and styrene in the presence of preformed polymethylmethacrylate latexes resulted in particles with a core-shell morphology, as determined by small-angle neutron scattering (SANS) analysis for a hollow sphere. The locus of polymerization of the added deuterated monomer is therefore at the particle surface. In similar measurements a statistical copolymer of styrene and methyl methacrylate was used as seed particles for further polymerization of trideuteromethyl methacrylate. The resulting polymer latex was again shown to have a core-shell morphological structure as determined by SANS. SANS experiments were also undertaken on polystyrene latexes polymerized by equilibrium swelling methods, with deuterated polymer forming the first or second step. The experiments covered a molecular weight range of 6 x 10{sup 4} 10{sup 6} the molecular weights are consistent with the experimental errors, indicating that the deuterium labeled molecules are randomly distributed in the latex. These results led to the finding that the polymer chains were constrained in the latex particles by factors of 2 to 4 from the relaxed coil dimensions. For M molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights.

  17. Pressure-induced polymerization of phenoxyethyl acrylate

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, K; Wrzalik, R; Paluch, M; Ziolo, J [Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice (Poland); Roland, C M [Naval Research Laboratory, Chemistry Division, Code 6120, Washington, DC 20375-5342 (United States)

    2008-06-18

    Polymerization of phenoxyethyl acrylate was induced without catalyst or initiators by the application of hydrostatic pressure at elevated temperature. Broadband dielectric and infrared spectroscopy were employed to follow the course of the reaction, which reached a degree of conversion of 60%. The structure of the obtained polymer was determined from density functional theory calculations.

  18. Immobilization of Trichoderma reesei by radiation polymerization

    International Nuclear Information System (INIS)

    Zhou Ruimin; Ma Zueteh; Kaetus, Isao; Kumakura, Minoro

    1993-01-01

    Immobilization of Trichoderma reesei was carried out by radiation polymerization. It was found that the activity of fixed cells increased with increasing surface area of the carrier and was affected by the concentration of monomer tetraethylenglycol dimethacrylate and the shape of the substrate composition and structure of cotton textile fabrics. (author)

  19. Polymerization of different lignins by laccase

    NARCIS (Netherlands)

    Mattinen, M.L.; Suortti, T.; Gosselink, R.J.A.; Argyropoulos, D.S.; Evtuguin, D.; Suurnäkki, A.; Jong, de E.; Tamminen, T.

    2008-01-01

    In this study the oxidative polymerization of different lignins, i.e. Flax Soda lignin, Spruce EMAL, and Eucalyptus Dioxane lignin by Trametes hirsuta laccase was compared. Initially the structures of the different lignins were compared by Fourier transform infrared spectroscopy. The reactivity of

  20. Interaction of acetamiprid with extracellular polymeric substances ...

    African Journals Online (AJOL)

    Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was ...

  1. Radiation sterilization of polymeric implant materials

    International Nuclear Information System (INIS)

    Bruck, S.D.; Mueller, E.P.

    1988-01-01

    High-energy irradiation sterilization of medical devices and implants composed of polymeric biomaterials that are in contact with tissue and/or blood, may adversely affect their long-term mechanical and/or biological performance (tissue and/or blood compatibility). Since many polymeric implants may contain trace quantities of catalysts and/or other additives, the effect of high-energy radiation on these additives, and possible synergistic effects with the polymer chains under the influence of high-energy radiation, must be considered. It is essential to indicate whether polymeric implants are used in short-term (acute) or long-term (chronic) applications. Relatively small changes in their physicochemical, mechanical, and biological properties may be tolerable in the short term, whereas similar changes may lead to catastrophic failures in long-term applications. Therefore, polymeric implants which are to be sterilized by high-energy irradiation should be carefully evaluated for long-term property changes which may be induced by the radiation

  2. Ion induced polymerization in benzene frozen films

    Energy Technology Data Exchange (ETDEWEB)

    Calcagno, G [Catania Univ. (Italy). Ist. di Fisica; Strazzulla, G [Catania Univ. (Italy). Osservatorio Astrofisico; Fichera, M; Foti, G [Catania Univ. (Italy). Ist. di Radiologia

    1983-07-01

    The cross section of the polymerization process induced by energetic protons colliding with frozen benzene layers has been measured. The results have been described by a simple theory and they show that the process is a volume one occurring along the ion track and interesting all of the crossed layers.

  3. Vinyl acetate polymerization by ionizing radiation

    International Nuclear Information System (INIS)

    Mesquita, Andrea Cercan

    2002-01-01

    The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60 Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

  4. Microfluidic production of polymeric micro- and nanoparticles

    NARCIS (Netherlands)

    Serra, C.; Kahn, I.U.; Cortese, B.; Croon, de M.H.J.M.; Hessel, V.; Ono, T.; Anton, N.; Vandamme, Th.

    2013-01-01

    Polymeric micro- and nanoparticles have attracted a wide attention of researchers in various areas such as drug delivery, sensing, imaging, cosmetics, diagnostics, and biotechnology. However, processes with conventional equipment do not always allow a precise control of their morphology, size, size

  5. Characteristic emission in glutaraldehyde polymerized hemoglobin

    International Nuclear Information System (INIS)

    Ma Li; Wang Xiaojun

    2011-01-01

    Hemoglobin with different modifications has been investigated using spectroscopic techniques. A new emission at around 371 nm has been observed under excitation of 305 nm from glutaraldehyde polymerized human hemoglobin. Intensity and peak position of the emission are dependent on both oxidation state and ligand environment and the emission has been identified from the hemoglobin oligomer.

  6. Photoinduced polymerization from direct and sensitized excitation of maleimides

    International Nuclear Information System (INIS)

    Jonsson, S.; Lindgren, K.; Yang, D.; Viswanathan, K.; Nguyen, C.K.; Hoyle, C.

    2000-01-01

    Full text: The efficient photoinitiated polymerization by excited state acceptor monomers, such as maleimides (MI), has been shown in numerous acceptor/donor pair combinations. The strong hydrogen abstractability of excited triplet state MIs have also been evaluated for the initiation of acrylate polymerization and were found to be comparable in efficiency to 'the state of the art' α-cleavage type of photoinitiators. Furthermore, the importance of available abstractable hydrogens as well as the relative abstractabilities has been determined. The unique feature of MIs in general is its dual effect of simultaneously acting as a photoinitiator and as a polymerizable monomer. Once the initiation by photolysis of the acceptor / H-donors has generated a sufficient number of radicals, the unphotolyzed ground state acceptor will copolymerize with the selected monomers chosen. Although the influence of structural variations of the maleimide N-substituent, average functionality, temperature, light intensity, donor structure and acceptor / donor ratio have been carefully investigated, very little information regarding the initiating mechanism has been reported. In this paper, laser flash photolysis has been used in order to clarify and experimentally provide evidence for the mechanism of initiation. The acceptor transient intermediate generated by flash photolysis is readily quenched by typical triplet quenchers. Furthermore, selfquenching and reduction of transient lifetimes as a function of increasing concentrations of typical hydrogen donors have been determined. Stern-Volmer quenching rate constants for direct versus electron transfer induced hydrogen abstractions are calculated and compared to typical H-abstracting photoinitiators such as benzophenone (BP) and thioxanthone derivatives (ITX). From these comparisons it is clear that some triplet state MIs are more efficient in H-abstraction than the corresponding triplet states of BP and ITX. A strong and expected

  7. Carboxyl-Functionalized Polymeric Microspheres Prepared by One-Stage Photoinitiated RAFT Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Jianbo Tan

    2017-12-01

    Full Text Available Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT dispersion copolymerization of methyl methacrylate (MMA and methyl methacrylic (MAA for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag composite microspheres were prepared by in situ reduction of AgNO3 using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB with NaBH4 as a reductant.

  8. SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

    Institute of Scientific and Technical Information of China (English)

    Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

    2000-01-01

    Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

  9. TRANSITION METAL CATALYSIS IN CONTROLLED RADICAL POLYMERIZATION: ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    Science.gov (United States)

    Novel and diversified macromolecular structures, which include polymers with designed topologies (top), compostions (middle), and functionalities (bottom), can be prepared by atom transfer radical polymerization processes. These polymers can be synthesized from a large variety of...

  10. Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

    International Nuclear Information System (INIS)

    Galhardo, Eduardo; Lona, Liliane M.F.

    2009-01-01

    Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

  11. 21 CFR 870.3650 - Pacemaker polymeric mesh bag.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

  12. FtsZ Polymerization Assays : Simple Protocols and Considerations

    NARCIS (Netherlands)

    Król, Ewa; Scheffers, Dirk-Jan

    2013-01-01

    During bacterial cell division, the essential protein FtsZ assembles in the middle of the cell to form the so-called Z-ring. FtsZ polymerizes into long filaments in the presence of GTP in vitro, and polymerization is regulated by several accessory proteins. FtsZ polymerization has been extensively

  13. THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-P-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERIZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    QIU Kunyuan; ZHANG Zhanghua; FENG Xinde

    1992-01-01

    The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.

  14. A theory for fracture of polymeric gels

    Science.gov (United States)

    Mao, Yunwei; Anand, Lallit

    2018-06-01

    A polymeric gel is a cross-linked polymer network swollen with a solvent. If the concentration of the solvent or the deformation is increased to substantial levels, especially in the presence of flaws, then the gel may rupture. Although various theoretical aspects of coupling of fluid permeation with large deformation of polymeric gels are reasonably well-understood and modeled in the literature, the understanding and modeling of the effects of fluid diffusion on the damage and fracture of polymeric gels is still in its infancy. In this paper we formulate a thermodynamically-consistent theory for fracture of polymeric gels - a theory which accounts for the coupled effects of fluid diffusion, large deformations, damage, and also the gradient effects of damage. The particular constitutive equations for fracture of a gel proposed in our paper, contain two essential new ingredients: (i) Our constitutive equation for the change in free energy of a polymer network accounts for not only changes in the entropy, but also changes in the internal energy due the stretching of the Kuhn segments of the polymer chains in the network. (ii) The damage and failure of the polymer network is taken to occur by chain-scission, a process which is driven by the changes in the internal energy of the stretched polymer chains in the network, and not directly by changes in the configurational entropy of the polymer chains. The theory developed in this paper is numerically implemented in an open-source finite element code MOOSE, by writing our own application. Using this simulation capability we report on our study of the fracture of a polymeric gel, and some interesting phenomena which show the importance of the diffusion of the fluid on fracture response of the gel are highlighted.

  15. Short proofs of strong normalization

    OpenAIRE

    Wojdyga, Aleksander

    2008-01-01

    This paper presents simple, syntactic strong normalization proofs for the simply-typed lambda-calculus and the polymorphic lambda-calculus (system F) with the full set of logical connectives, and all the permutative reductions. The normalization proofs use translations of terms and types to systems, for which strong normalization property is known.

  16. NATO Advanced Study Institute on Ring-opening Metathesis Polymerization of Olefins and Polymerization of Alkynes

    CERN Document Server

    1998-01-01

    The first NATO Advanced Study Institute on Olefin Metathesis and Polymerization Catalysts was held on September 10-22, 1989 in Akcay, Turkey. Based on the fundamental research of RRSchrock, RGrubbs and K.B.Wagener in the field of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) and alkyne polymerization, these areas gained growing interest within the last years. Therefore the second NATO-ASI held on metathesis reactions was on Ring Opening Metathesis Po­ lymerization of Olefins and Polymerization of Alkynes on September 3-16, 1995 in Akcay, Turkey. The course joined inorganic, organic and polymer chemists to exchange their knowledge in this field. This volume contains the main and short lectures held in Akcay. To include ADMET reactions better into the title of this volume we changed it into: Metathesis Polymerization of Olefins and Alkyne Polymerization. This volume is addressed to research scientists, but also to those who start to work in the area of olefin metathesis and al...

  17. Strong-back safety latch

    International Nuclear Information System (INIS)

    DeSantis, G.N.

    1995-01-01

    The calculation decides the integrity of the safety latch that will hold the strong-back to the pump during lifting. The safety latch will be welded to the strong-back and will latch to a 1.5-in. dia cantilever rod welded to the pump baseplate. The static and dynamic analysis shows that the safety latch will hold the strong-back to the pump if the friction clamps fail and the pump become free from the strong-back. Thus, the safety latch will meet the requirements of the Lifting and Rigging Manual for under the hook lifting for static loading; it can withstand shock loads from the strong-back falling 0.25 inch

  18. Phosphazene-promoted metal-free ring-opening polymerization of ethylene oxide initiated by carboxylic acid

    KAUST Repository

    Zhao, Junpeng; Pahovnik, David; Gnanou, Yves; Hadjichristidis, Nikolaos

    2014-01-01

    The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation

  19. Copolymer Synthesis and Characterization by Post-Polymerization Modification

    Science.gov (United States)

    Galvin, Casey James

    developing technologies that use SGPAs in aqueous environments, and point to a need for potential alternative grafting chemistries. The behavior of SGPAs in vapor environments remains an underexplored phenomenon. By changing systematically the chemistry of SGPAs derived from a parent sample, the influence of side chain functional groups on the swelling of weak and strong polyelectrolyte brushes in the presence of water, methanol and ethanol vapors is explored. The extent of swelling and solvent uptake depends strongly on the chemistry in the polymer side chain and of the solvent. Despite bearing a permanent electrostatic charge in the side chain, the strong polyelectrolyte brushes exhibit no behavior typical of polyelectrolytes in water due to no dissociation of the counterion. Of particular interest is the behavior in humid environments of an SGPA bearing a zwitterionic group in its side chain, which results in exposure of electrostatic charges without counterions. Using substrates bearing the aforementioned sigma gradient of polymeric grafts, evidence of inter- and intramolecular complex formation is presented. Finally, a method of developing SGPAs by polymerizing bulk polymer chains through surface-grafted monomers (SGMs) is described. The SGMs are incorporated onto a solid substrate using the same PPM reaction employed in the degrafting and vapor swelling experiments, highlighting the versatility of PPM. The thickness of these SGPAs is correlated to the bulk polymer chains MW, suggesting this technique can be used in existing industrial bulk polymerization processes.

  20. Antibiotic polymeric nanoparticles for biofilm-associated infection therapy.

    Science.gov (United States)

    Cheow, Wean Sin; Hadinoto, Kunn

    2014-01-01

    Polymeric nanoparticles are highly attractive as drug delivery vehicles due to their high structural integrity, stability during storage, ease of preparation and functionalization, and controlled release capability. Similarly, lipid-polymer hybrid nanoparticles, which retain the benefits of polymeric nanoparticles plus the enhanced biocompatibility and prolonged circulation time owed to the lipids, have recently emerged as a superior alternative to polymeric nanoparticles. Drug nanoparticle complex prepared by electrostatic interaction of oppositely charged drug and polyelectrolytes represents another type of polymeric nanoparticle. This chapter details the preparation, characterization, and antibiofilm efficacy testing of antibiotic-loaded polymeric and hybrid nanoparticles and antibiotic nanoparticle complex.

  1. Studies on Rate Enhancement of Polymerization in NMRP

    Institute of Scientific and Technical Information of China (English)

    HUANG Jian-ying; XU Miao-qing; YAN Ming-fa; CHEN Yi-hong; CHU Jia-yan; ZHUANG Jia-ming; DAI Li-zong; ZOU You-si

    2005-01-01

    In NMRP, the polymerization of MMA, the polymerization of St and the copolymerization of MMA with St were distinctly accelerated by the addition of a small amount of MN. The polymerization proceeds in a living fashion as indicated by the increase in molecular weight with the increase of time and conversion and a relatively low polydispersity. It has been found that the addition of MN results in a nearly one hundred times higher rate of the polymerization of MMA, a nearly twenty times higher rate of the polymerization of St and a nearly fifteen times higher rate of the copolymerization of St and MMA.

  2. Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

    Science.gov (United States)

    Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

    1995-01-01

    Production of an electric voltage in response to mechanical excitation (piezoelectricity) or thermal excitation (pyroelectricity) requires a material to have a preferred dipole orientation in its structure. This preferred orientation or polarization occurs naturally in some crystals such as quartz and can be induced into some ceramic and polymeric materials by application of strong electric or mechanical fields. For some materials, a combination of mechanical and electrical orientation is necessary to completely polarize the material. The only commercially available piezoelectric polymer is poly(vinylidene fluoride) (PVF2). However, this polymer has material and process limitations which prohibit its use in numerous device applications where thermal stability is a requirement. By the present invention, thermally stable, piezoelectric and pyroelectric polymeric substrates were prepared from polymers having a softening temperature greater than 1000C. A metal electrode material is deposited onto the polymer substrate and several electrical leads are attached to it. The polymer substrate is heated in a low dielectric medium to enhance molecular mobility of the polymer chains. A voltage is then applied to the polymer substrate inducing polarization. The voltage is then maintained while the polymer substrate is cooled 'freezing in' the molecular orientation. The novelty of the invention resides in the process of preparing the piezoelectric and pyroelectric polymeric substrate. The nonobviousness of the invention is found in heating the polymeric substrate in a low dielectric medium while applying a voltage.

  3. Polymerization shrinkage stress of composite resins and resin cements – What do we need to know?

    Directory of Open Access Journals (Sweden)

    Carlos José SOARES

    2017-08-01

    Full Text Available Abstract Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

  4. Polymerization shrinkage stress of composite resins and resin cements - What do we need to know?

    Science.gov (United States)

    Soares, Carlos José; Faria-E-Silva, André Luis; Rodrigues, Monise de Paula; Vilela, Andomar Bruno Fernandes; Pfeifer, Carmem Silvia; Tantbirojn, Daranee; Versluis, Antheunis

    2017-08-28

    Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

  5. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  6. Hyperbranched polymers from polymerization in solid state

    International Nuclear Information System (INIS)

    Tomaz, Vivian A.; Silva, Rafael; Muniz, Edvani C.; Rubira, Adley F.

    2009-01-01

    The macroscopic properties of polymers are directly related to the chemical characteristics of the monomeric units and also with the geometric arrangement of polymer chains. Thus, polymers were synthesized from two well-known chelators EDTA and EDA. We evaluated the conditions for the polymerization of the precursors in the solid state. The polymerization was carried out varying the proportions of reagents, aiming the polymers with different degrees of chain branching and the materials were characterized by FTIR. The materials obtained from the best condition for synthesis were purified by size-exclusion chromatography of and were subjected to characterization by FTIR and NMR of 1 H and 13 C. The content of end groups in these samples was determined by back titration. (author)

  7. Studies on radiation-induced graft polymerization

    International Nuclear Information System (INIS)

    Omichi, Hideki

    1978-09-01

    Radiation-induced graft polymerization is used extensively to improve physical properties of polymers, but few processes are now commercialized. The reason for this is partly inadequate basic research on the reaction and partly the difficulty in developing the grafting process with large radiation source. Firstly, new techniques are proposed of studying kinetics of the graft polymerization in heterogeneous system. Based on the grafting yield, the molecular weight of graft chains, and the amount of radicals given by ESR and activation analysis, kinetic parameters are obtained and the reaction mechanism of grafting process is discussed. Secondly, the development of grafting process of poly (vinyl chloride)-butadiene is described. By study of the reaction, process design, construction and operation of the pilot plant, and economic analysis of the process, this process with 60 Co gamma ray sources is shown to be industrially promising. (author)

  8. Radiation-induced emulsion polymerization of tetrafluoroethylene

    International Nuclear Information System (INIS)

    Suwa, Takeshi

    1979-10-01

    The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene (TFE) has been studied at initial pressure 2 - 25 kg/cm 2 and temperature 30 0 - 110 0 C for dose rate 0.57 x 10 4 - 3.0 x 10 4 rad/hr. Polytetrafluoroethylene (PTFE), a hydrophobic polymer, forms as a stable latex in the absence of an emulsifier. Stability of the latex is governed by the dose rate/TFE pressure ratio; it increases with sufficient TFE monomer. PTFE particles produced in this polymerization system are stable due to the carboxyl end groups and adsorption of OH - and HF on the particles. PTFE latex of molecular weight higher than 2 x 10 7 is obtained by addition of a radical scavenger such as hydroquinone. The molecular weight of PTFE can be measured from the heat of crystallization conveniently with high reliability, which was found in the course of study on the melting and crystallization behavior. (author)

  9. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Hassager, Ole; Kristensen, Susanne Brogaard; Larsen, Johannes Ruben

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric material is described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney......-Rivlin model show a monotone increasing pressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...... inflated. Membranes described by these models develop a local thinning of the membrane which may lead to bursting in finite time. (C) 1999 Elsevier Science B.V. All rights reserved....

  10. Radiation polymerization of tetrafluoroethylene in freon-22

    International Nuclear Information System (INIS)

    Schnautz, N.G.; Thompson, J.C.

    1979-02-01

    The radiation-induced solution-polymerization of tetrafluoroethylene in Freon-22 has been investigated over a temperature range of - 62 degrees celcius to 0 degrees celcius. The rate of polymerization for the in-source process was found to be directly propertional to monomer concentration and an activation energy of only 7,66 kj/mole was calculated. The number-average molecular mass of the product PTFE ranged from 2X10 4 to 6X10 4 and was relatively independent of the usual reaction parameters. The rate of postpolymerization was also found to be directly proportional to monomer concentration. The postpolyerization process did not result in any enchancement of the initial PTFE molecular mass [af

  11. Self-folding micropatterned polymeric containers.

    Science.gov (United States)

    Azam, Anum; Laflin, Kate E; Jamal, Mustapha; Fernandes, Rohan; Gracias, David H

    2011-02-01

    We demonstrate self-folding of precisely patterned, optically transparent, all-polymeric containers and describe their utility in mammalian cell and microorganism encapsulation and culture. The polyhedral containers, with SU-8 faces and biodegradable polycaprolactone (PCL) hinges, spontaneously assembled on heating. Self-folding was driven by a minimization of surface area of the liquefying PCL hinges within lithographically patterned two-dimensional (2D) templates. The strategy allowed for the fabrication of containers with variable polyhedral shapes, sizes and precisely defined porosities in all three dimensions. We provide proof-of-concept for the use of these polymeric containers as encapsulants for beads, chemicals, mammalian cells and bacteria. We also compare accelerated hinge degradation rates in alkaline solutions of varying pH. These optically transparent containers resemble three-dimensional (3D) micro-Petri dishes and can be utilized to sustain, monitor and deliver living biological components.

  12. Polymeric membrane studied using slow positron beam

    International Nuclear Information System (INIS)

    Hung, W.-S.; Lo, C.-H.; Cheng, M.-L.; Chen Hongmin; Liu Guang; Chakka, Lakshmi; Nanda, D.; Tung, K.-L.; Huang, S.-H.; Lee, Kueir-Rarn; Lai, J.-Y.; Sun Yiming; Yu Changcheng; Zhang Renwu; Jean, Y.C.

    2008-01-01

    A radioisotope slow positron beam has been built at the Chung Yuan Christian University in Taiwan for the research and development in membrane science and technology. Doppler broadening energy spectra and positron annihilation lifetime have been measured as a function of positron energy up to 30 keV in a polyamide membrane prepared by the interfacial polymerization between triethylenetetraamine (TETA) and trimesoyl chloride (TMC) on modified porous polyacrylonitrile (PAN) asymmetric membrane. The multilayer structures and free-volume depth profile for this asymmetric membrane system are obtained. Positron annihilation spectroscopy coupled with a slow beam could provide new information about size selectivity of transporting molecules and guidance for molecular designs in polymeric membranes

  13. Radiation-induced polymerization of hydrogen cyanide

    International Nuclear Information System (INIS)

    Mozhaev, P.S.; Kichigina, G.A.; Kiryukhin, D.P.

    1995-01-01

    The chain reaction of HCN polymerization in a γ-radiation field does not occur at 77 K. When irradiated HCN is warmed up to ambient temperature, a polymer is formed. The heat of polymerization of HCN is 44.0±6.0 kJ/mol and the polymer yield reaches 2.5% for a dose of 725 kGy. Amorphous polymer products (with yields increasing up to 33.5%) and needle crystals (presumably HCN tetramer) are formed upon storage of irradiated HCN at room temperature. The polymer is stable below 700 K, has a conductivity of 3x10 -5 Ω -1 cm -f1 , and displays an EPR spectrum typical of polyconjugated systems. A radical mechanism of the formation of conjugated chain -C=N-C=N- is suggested. The tetramer is produced by a combination of aminocyanocarbene biradicals

  14. RAFT polymerization and some of its applications.

    Science.gov (United States)

    Moad, Graeme; Rizzardo, Ezio; Thang, San H

    2013-08-01

    Reversible addition-fragmentation chain transfer (RAFT) is one of the most robust and versatile methods for controlling radical polymerization. With appropriate selection of the RAFT agent for the monomers and reaction conditions, it is applicable to the majority of monomers subject to radical polymerization. The process can be used in the synthesis of well-defined homo-, gradient, diblock, triblock, and star polymers and more complex architectures, which include microgels and polymer brushes. In this Focus Review we describe how the development of RAFT and RAFT application has been facilitated by the adoption of continuous flow techniques using tubular reactors and through the use of high-throughput methodology. Applications described include the use of RAFT in the preparation of polymers for optoelectronics, block copolymer therapeutics, and star polymer rheology control agents. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Forming of Polymeric Tubular Micro-components

    DEFF Research Database (Denmark)

    Qin, Yi; Zhao, Jie; Anyasodor, Gerald

    2015-01-01

    platform for the production of functional polymeric tubular micro-components. The chapter gives background on the current market and process development trends, followed by description of materials, process configuration, tool design and machine development for each processing technology as well......This chapter is intended to provide an overview of three nontraditional shaping technologies for the forming of polymeric micro-tubes, which are hot embossing, blow molding, and cross rolling, as well as realization of a process chain and the integration of a modular machine-based manufacturing...... as strategy for integration of the technologies and equipment into a common platform. Finally, potential applications of the technologies and facilities developed are highlighted....

  16. Polyisoprene Nanoparticles Prepared by Polymerization in Microemulsion

    Directory of Open Access Journals (Sweden)

    Y. Apolinar

    2010-01-01

    Full Text Available Batch polymerization of isoprene was carried out at 25∘C in a normal microemulsion stabilized with sodium dodecyl sulfate and initiated with the redox couple tert-butyl hydroperoxide/tetraethylene-pentamine. Characterization by transmission electronic microscopy showed that polyisoprene nanoparticles with number-average diameter close to 20 nm were obtained. The low molecular weights obtained, as determined by gel permeation chromatography, were probably due to chain scission as inferred from the oxidative ambient at which polymerization was carried out. Microstructure calculated from infrared spectroscopy data indicates that the obtained polyisoprene contains around 80% total 1,4 units, which is in accordance with its glass transition temperature (-60.8∘C determined by differential scanning calorimetry.

  17. Pharmaceutical Applications of Polymeric Nano materials

    International Nuclear Information System (INIS)

    Wu, L.; Sun, L.

    2011-01-01

    With significant attention focused on nano science and nano technology in recent years, nano materials have been used in a wide variety of applications such as automotive, environmental, energy, catalysis, biomedical, drug delivery, and polymeric industries. Among those fields, the application of nano materials with pharmaceutical science is an emerging and rapidly growing field and has drawn increasing attention recently. Research and development in this field is mainly focused on several aspects such as the discoveries of novel functional nano materials, exploration on nanoparticles with controlled and targeted drug delivery characteristics, and investigation of bio functionalized and diagnostic nano materials. In this special issue, we have invited a few papers related to recent advances in pharmaceutical application of polymeric nano materials

  18. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5 - Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    The mesomorphic properties and thermal stability of side-chain LC polycarbonates with alkoxyphenyl benzoate side groups having a short spacer and alkoxy tails ranging from 1 to 8 carbon atoms were studied by DSC, X-ray diffraction and polarized light optical microscopy. All polymers have a smectic A

  19. Liquid Crystalline Polymers Containing Heterocycloalkane Mesogens. 2. Side-Chain Liquid Crystalline Polysiloxanes Containing 2,5-Disubstituted-1,3-Dioxane Mesogens.

    Science.gov (United States)

    1986-10-01

    groups. In the previous paper from this series (47) we presented the synthesis and characterization of several polyacrylates and polymethacrylates based...dilute sulfuric acid (14.5 ml of concentrated sulfuric acid in 250 ml of water). An almost colorless oil separated from the aqueous phase. The two...of 10% sulfuric acid and extracted with chloroform. The organic phase was washed with 2% aqueous sodium bicarbonate, water and dried over anhydrous

  20. EDOT polymerization at photolithographically patterned functionalized graphene

    Czech Academy of Sciences Publication Activity Database

    Kovaříček, Petr; Drogowska, Karolina; Melníková Komínková, Zuzana; Blechta, Václav; Bastl, Zdeněk; Gromadzki, Daniel; Fridrichová, Michaela; Kalbáč, Martin

    2017-01-01

    Roč. 113, MAR 2017 (2017), s. 33-39 ISSN 0008-6223 R&D Projects: GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551 Institutional support: RVO:61388955 Keywords : polymerization * electrochemical doping * graphene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 6.337, year: 2016

  1. Emulsion polymerization with high energy radiation

    International Nuclear Information System (INIS)

    Stannett, V.T.; Stahel, E.P.

    1992-01-01

    High energy radiation, particularly that of cobalt-60 or caesium-137 gamma-rays, provides in principle an ideal initiator for emulsion polymerization. The high free radical yields from the radiolysis of the aqueous phase combined with the high kinetic chain lengths associated with emulsion polymerization lead to a highly effective utilization of the radiation. There are other important advantages compared with the use of chemical initiators such as potassium persulfate. These are outlined in the chapter, together with some attendant disadvantages. Radiation-induced initiation is temperature independent, and low temperature polymerizations can be conducted with ease. Monomers that mainly terminate their growing chains by chain transfer to monomer give higher molecular weights at lower temperatures. Industrially, vinyl acetate is an important example of such a monomer, and it has been studied using radiation initiation. Both laboratory and pilot plant studies have been carried out and reported. The results are summarized in this chapter. Styrene is the classical example of a material that under a number of conditions closely obeys the so-called ideal Smith-Ewart kinetics. It has been found that under similar conditions but substituting radiation for potassium persulfate as the initiator, ideal kinetics were closely followed. Most of the conventional and some non-standard vinyl and diene monomers have been studied to some extent with radiation-initiated polymerizations in emulsion. To conserve space however, this chapter presents and discusses the results obtained only with styrene and vinyl acetate, both in laboratory and pilot plant investigations. Other monomers and special situations are referenced either directly or to the other available reviews. (orig.)

  2. Personal Cooling Fabric Based on Polymeric Thermoelectrics

    Science.gov (United States)

    2016-07-28

    There are also concerns about environmental impact given their toxic heavy metal content. Despite these limitations and the lack of improvement in...polymeric TE materials were studied, they offered the additional advantages (over metallic materials) of low density, no toxic heavy metals (bismuth, lead...First, fluorene was reacted with two equivalents of bromoethane under basic conditions to afford 9,9’-diethyl fluorine , which was bromomethylated

  3. High-voltage polymeric insulated cables

    Energy Technology Data Exchange (ETDEWEB)

    Ross, A

    1987-01-01

    Reviews developments in high-voltage (here defined as 25 kV, 66 kV and 132 kV) polymeric insulated cables in the UK over the period 1979-1986, with particular reference to the experience of the Eastern Electricity Board. Outlines the background to the adoption of XPLE-insulated solid cable, and the design, testing, terminations, jointing and costs of 25 kV, 66 kV and 132 kV cables.

  4. Adaptive polymeric system for Hebbian type learning

    OpenAIRE

    2011-01-01

    Abstract We present the experimental realization of an adaptive polymeric system displaying a ?learning behaviour?. The system consists on a statistically organized networks of memristive elements (memory-resitors) based on polyaniline. In a such network the path followed by the current increments its conductivity, a property which makes the system able to mimic Hebbian type learning and have application in hardware neural networks. After discussing the working principle of ...

  5. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  6. Comparison of potentials for polymeric liquids

    International Nuclear Information System (INIS)

    Jung, Hae Young

    2002-01-01

    Many theories for polymeric liquids are based on the concepts of cell, hole, free volume of lattice etc. In this theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used. In this work, Mie(p,6)potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equation of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values changing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid theory, Flory's Equation of State Theory and Cho-Sanchez Theory using perturbation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p,6) potential for polymeric liquids were compared with each other

  7. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  8. Mechanically Strong Lightweight Materials for Aerospace Applications (x-aerogels)

    Science.gov (United States)

    Leventis, Nicholas

    2005-01-01

    The X-Aerogel is a new NASA-developed strong lightweight material made by reacting the mesoporous surfaces of 3-D networks of inorganic nanoparticles with polymeric crosslinkers. Since the relative amount of the crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by templated casting of polymeric precursors on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralightweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the thermal conductivity of styrofoam. XAerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a wide variety of dimensionally stable, porous lightweight materials with interesting structural, magnetic and optical properties. X-Aerogels are evaluated for cryogenic rocket fuel storage tanks and for Advanced EVA suits, where they will play the dual role of the thermal insulator/structural material. Along the same lines, major impact is also expected by the use of X-Aerogels in structural components/thermal protection for small satellites, spacecrafts, planetary vehicles and habitats.

  9. KINETICS OF SUSPENDED EMULSION POLYMERIZATION OF METHYL METHACRYLATE

    Institute of Scientific and Technical Information of China (English)

    Yong-zhong Bao; Cheng-xi Wang; Zhi-ming Huang; Zhi-xue Weng

    2004-01-01

    The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (Rp0) and steady-state polymerization rate (Rp) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: Rp0 ∝ [I]0.73[S]0.32 and Rp ∝ [I]0.71[S]0.23. The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.

  10. Strong coupling phase in QED

    International Nuclear Information System (INIS)

    Aoki, Ken-ichi

    1988-01-01

    Existence of a strong coupling phase in QED has been suggested in solutions of the Schwinger-Dyson equation and in Monte Carlo simulation of lattice QED. In this article we recapitulate the previous arguments, and formulate the problem in the modern framework of the renormalization theory, Wilsonian renormalization. This scheme of renormalization gives the best understanding of the basic structure of a field theory especially when it has a multi-phase structure. We resolve some misleading arguments in the previous literature. Then we set up a strategy to attack the strong phase, if any. We describe a trial; a coupled Schwinger-Dyson equation. Possible picture of the strong coupling phase QED is presented. (author)

  11. Neutral Polymeric Micelles for RNA Delivery

    Science.gov (United States)

    Lundy, Brittany B.; Convertine, Anthony; Miteva, Martina; Stayton, Patrick S.

    2013-01-01

    RNA interference (RNAi) drugs have significant therapeutic potential but delivery systems with appropriate efficacy and toxicity profiles are still needed. Here, we describe a neutral, ampholytic polymeric delivery system based on conjugatable diblock polymer micelles. The diblock copolymer contains a hydrophilic poly[N-(2-hydroxypropyl) methacrylamide-co-N-(2-(pyridin-2- yldisulfanyl)ethyl)methacrylamide) (poly[HPMA-co-PDSMA]) segment to promote aqueous stability and facilitate thiol-disulfide exchange reactions, and a second ampholytic block composed of propyl acrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), and butyl methacrylate (BMA). The poly[(HPMA-co-PDSMA)-b-(PAA-co-DMAEMA-co-BMA)] was synthesized using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization with an overall molecular weight of 22,000 g/mol and a PDI of 1.88. Dynamic light scattering and fluorescence measurements indicated that the diblock copolymers self-assemble under aqueous conditions to form polymeric micelles with a hydrodynamic radius and critical micelle concentration of 25 nm and 25 μg/mL respectively. Red blood cell hemolysis experiments show that the neutral hydrophilic micelles have potent membrane destabilizing activity at endosomal pH values. Thiolated siRNA targeting glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was directly conjugated to the polymeric micelles via thiol exchange reactions with the pyridal disulfide groups present in the micelle corona. Maximum silencing activity in HeLa cells was observed at a 1:10 molar ratio of siRNA to polymer following a 48 h incubation period. Under these conditions 90 % mRNA knockdown and 65 % and protein knockdown of at 48 h was achieved with negligible toxicity. In contrast the polymeric micelles lacking a pH-responsive endosomalytic segment demonstrated negligible mRNA and protein knockdown under these conditions. The potent mRNA knockdown and excellent biocompatibility of the neutral siRNA conjugates

  12. LL-37 induces polymerization and bundling of actin and affects actin structure.

    Directory of Open Access Journals (Sweden)

    Asaf Sol

    Full Text Available Actin exists as a monomer (G-actin which can be polymerized to filaments F-actin that under the influence of actin-binding proteins and polycations bundle and contribute to the formation of the cytoskeleton. Bundled actin from lysed cells increases the viscosity of sputum in lungs of cystic fibrosis patients. The human host defense peptide LL-37 was previously shown to induce actin bundling and was thus hypothesized to contribute to the pathogenicity of this disease. In this work, interactions between actin and the cationic LL-37 were studied by optical, proteolytic and surface plasmon resonance methods and compared to those obtained with scrambled LL-37 and with the cationic protein lysozyme. We show that LL-37 binds strongly to CaATP-G-actin while scrambled LL-37 does not. While LL-37, at superstoichiometric LL-37/actin concentrations polymerizes MgATP-G-actin, at lower non-polymerizing concentrations LL-37 inhibits actin polymerization by MgCl(2 or NaCl. LL-37 bundles Mg-F-actin filaments both at low and physiological ionic strength when in equimolar or higher concentrations than those of actin. The LL-37 induced bundles are significantly less sensitive to increase in ionic strength than those induced by scrambled LL-37 and lysozyme. LL-37 in concentrations lower than those needed for actin polymerization or bundling, accelerates cleavage of both monomer and polymer actin by subtilisin. Our results indicate that the LL-37-actin interaction is partially electrostatic and partially hydrophobic and that a specific actin binding sequence in the peptide is responsible for the hydrophobic interaction. LL-37-induced bundles, which may contribute to the accumulation of sputum in cystic fibrosis, are dissociated very efficiently by DNase-1 and also by cofilin.

  13. Strong interactions at high energy

    International Nuclear Information System (INIS)

    Anselmino, M.

    1995-01-01

    Spin effects in strong interaction high energy processes are subtle phenomena which involve both short and long distance physics and test perturbative and non perturbative aspects of QCD. Moreover, depending on quantities like interferences between different amplitudes and relative phases, spin observables always test a theory at a fundamental quantum mechanical level; it is then no surprise that spin data are often difficult to accommodate within the existing models. A report is made on the main issues and contributions discussed in the parallel Session on the open-quote open-quote Strong interactions at high energy close-quote close-quote in this Conference. copyright 1995 American Institute of Physics

  14. Strong-field dissociation dynamics

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, Baorui.

    1993-01-01

    The strong-field dissociation behavior of diatomic molecules is examined under two distinctive physical scenarios. In the first scenario, the dissociation of the isolated hydrogen and deuterium molecular ions is discussed. The dynamics of above-threshold dissociation (ATD) are investigated over a wide range of green and infrared intensities and compared to a dressed-state model. The second situation arises when strong-field neutral dissociation is followed by ionization of the atomic fragments. The study results in a direct measure of the atomic fragment's ac-Stark shift by observing the intensity-dependent shifts in the electron or nuclear fragment kinetic energy. 8 figs., 14 refs

  15. A novel synthesis of polymeric CO via useful hard X-ray photochemistry

    Directory of Open Access Journals (Sweden)

    Michael Pravica

    2016-12-01

    Full Text Available We report on the synchrotron hard X-ray-induced decomposition of strontium oxalate (SrC2O4 pressurized to 7 GPa inside a diamond anvil cell (DAC. After some 4 h of irradiation in a white X-ray synchrotron beam, a dark reddish/brown region formed in the area of irradiation which was surrounded by a yellowish brown remainder in the rest of the sample. Upon depressurization of the sample to ambient conditions, the reacted/decomposed sample was recoverable as a dark brown/red and yellow waxy solid. Synchrotron infrared spectroscopy confirmed the strong presence of CO2 even under ambient conditions with the sample exposed to air and other strongly absorbing regions, suggesting that the sample may likely be polymerized CO (in part with dispersed CO2 and SrO trapped within the polymer. These results will have significant implications in the ability to readily produce and trap CO2 in situ via irradiation of a simple powder for useful hard X-ray photochemistry and in the ability to easily manufacture polymeric CO (via loading of powders in a DAC or high volume press without the need for the dangerous and complex loading of toxic CO. A novel means of X-ray-induced polymerization under extreme conditions has also been demonstrated.

  16. A "catalyst switch" Strategy for the sequential metal-free polymerization of epoxides and cyclic Esters/Carbonate

    KAUST Repository

    Zhao, Junpeng

    2014-06-24

    A "catalyst switch" strategy was used to synthesize well-defined polyether-polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts. © 2014 American Chemical Society.

  17. SIMULTANEOUS MEASUREMENT OF FREE RADICAL DECAY IN POLYMERIZATION OF MMA INITIATED BY AIBN USING ESR AND ITS KINETIC MODEL

    Institute of Scientific and Technical Information of China (English)

    Ping Xia; Qing-song Hu; Xiao-lan Qian; Xul-in Jiang; De-yue Yan

    2001-01-01

    The kinetics of free radical decay in the polymerization of MMA initiated by AIBN was studied by means of ESR spectroscopy. It was found that the curves of radical decay are strongly associated with the reaction temperature, the initiator concentration and the solvent. In the case of the radical polymerization carried out at high temperature or in solution, the radical concentration first reached a maximum, then declined monotonously with reaction time. It was also found that the greater the amount of initiator or the higher the temperature, the more rapidly the radicals decay. When the bulk polymerization was implemented at a relatively low temperature, the curves of radical decay became more complicated, i.e.,the radical concentration rapidly rose to a maximum, then dropped to a minimum, finally increased again with reaction time.Taking into account the diffusion effect, a semi-empirical equation is suggested to describe the kinetics of propagating radical decay.

  18. A "catalyst switch" Strategy for the sequential metal-free polymerization of epoxides and cyclic Esters/Carbonate

    KAUST Repository

    Zhao, Junpeng; Pahovnik, David; Gnanou, Yves; Hadjichristidis, Nikolaos

    2014-01-01

    A "catalyst switch" strategy was used to synthesize well-defined polyether-polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts. © 2014 American Chemical Society.

  19. Strong Decomposition of Random Variables

    DEFF Research Database (Denmark)

    Hoffmann-Jørgensen, Jørgen; Kagan, Abram M.; Pitt, Loren D.

    2007-01-01

    A random variable X is stongly decomposable if X=Y+Z where Y=Φ(X) and Z=X-Φ(X) are independent non-degenerated random variables (called the components). It is shown that at least one of the components is singular, and we derive a necessary and sufficient condition for strong decomposability...... of a discrete random variable....

  20. Strong coupling electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Barklow, T.L.; Burdman, G.; Chivukula, R.S.

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models

  1. Strong coupling electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Barklow, T.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Burdman, G. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Chivukula, R.S. [Boston Univ., MA (United States). Dept. of Physics

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.

  2. The colours of strong interaction

    International Nuclear Information System (INIS)

    1995-01-01

    The aim of this session is to draw a consistent framework about the different ways to consider strong interaction. A large part is dedicated to theoretical work and the latest experimental results obtained at the first electron collider HERA are discussed. (A.C.)

  3. Strong cosmic censorship and the strong curvature singularities

    International Nuclear Information System (INIS)

    Krolak, A.

    1987-01-01

    Conditions are given under which any asymptotically simple and empty space-time that has a partial Cauchy surface with an asymptotically simple past is globally hyperbolic. It is shown that this result suggests that the Cauchy horizons of the type occurring in Reissner--Nordstroem and Kerr space-times are unstable. This in turn gives support for the validity of the strong cosmic censorship hypothesis

  4. Facile and Reliable in Situ Polymerization of Poly(Ethyl Cyanoacrylate)-Based Polymer Electrolytes toward Flexible Lithium Batteries.

    Science.gov (United States)

    Cui, Yanyan; Chai, Jingchao; Du, Huiping; Duan, Yulong; Xie, Guangwen; Liu, Zhihong; Cui, Guanglei

    2017-03-15

    Polycyanoacrylate is a very promising matrix for polymer electrolyte, which possesses advantages of strong binding and high electrochemical stability owing to the functional nitrile groups. Herein, a facile and reliable in situ polymerization strategy of poly(ethyl cyanoacrylate) (PECA) based gel polymer electrolytes (GPE) via a high efficient anionic polymerization was introduced consisting of PECA and 4 M LiClO 4 in carbonate solvents. The in situ polymerized PECA gel polymer electrolyte achieved an excellent ionic conductivity (2.7 × 10 -3 S cm -1 ) at room temperature, and exhibited a considerable electrochemical stability window up to 4.8 V vs Li/Li + . The LiFePO 4 /PECA-GPE/Li and LiNi 1.5 Mn 0.5 O 4 /PECA-GPE/Li batteries using this in-situ-polymerized GPE delivered stable charge/discharge profiles, considerable rate capability, and excellent cycling performance. These results demonstrated this reliable in situ polymerization process is a very promising strategy to prepare high performance polymer electrolytes for flexible thin-film batteries, micropower lithium batteries, and deformable lithium batteries for special purpose.

  5. Melting and crystallization of in-situ polymerized cyclic butylene terephthalates with and without organoclay: a modulated DSC study

    Directory of Open Access Journals (Sweden)

    2007-02-01

    Full Text Available The polymerization of cyclic butylene terephthalate oligomers (CBT were studied in presence (in 5 wt.% and absence of an organoclay (Cloisite® 30B by modulated DSC (MDSC. The organoclay containing samples were produced by dry and melt blending, respectively. The first heating, causing the polymerization of the CBT catalyzed by an organotin compound, was followed by cooling prior to the second heating. The MDSC scans covered the temperature interval between 0 and 260°C. The aim of this protocol was to study the crystallization and melting behavior of the resulting polybutylene terephthalate (pCBT and its organoclay modified nanocomposites. It was found that the thermal behaviors of the polymerizing and polymerized CBT (pCBT were strongly affected by the sample preparation. The organoclay suppressed the crystallization of the pCBT produced during the first heating. However, results from the second heating suggest that more perfect crystallites were formed in the organoclay modified pCBT variants. The organoclay also affected the conversion and mean molecular mass of the resulting pCBT which were slightly lower than those of the plain pCBT polymerized under identical conditions.

  6. Synthesis of acrylated palm oil nanoparticles using microemulsion polymerization initiated by gamma ray

    International Nuclear Information System (INIS)

    Rida Tajau; Wan Md Zin Wan Yunus; Khairul Zaman Mohd Dahlan; Mohd Hilmi Mahmood; Kamaruddin Hashim; Sim, Flora; Sharila Muhd Faizal

    2010-01-01

    The use of microemulsion in the development of nanoparticle based on acrylated palm oil product is demonstrated. The microemulsion polymerization was initiated by gamma ray for synthesizing crosslinked nanoparticle. Polymerization of acrylated palm oil in three-component ionic microemulsions was prepared with sodium dodecyl sulphate (SDS) and water. The resulted nanoparticle, before and after initiated by gamma ray, were evaluated in terms of particle diameter, surface charge and molecular structure. Type and concentration of surfactants, monomer concentration, radiation dose and time of storage strongly affected the size, charge and size stability of the particles. For the development of new microscopic polymer acrylated palm oil can be synthesized into nano sized particle and it has potential to be developed in medical devices and controlled-drug-release-applications. (author)

  7. Inelastic electron tunneling through degenerate and nondegenerate ground state polymeric junctions

    International Nuclear Information System (INIS)

    Golsanamlou, Z.; Bagheri Tagani, M.; Rahimpour Soleimani, H.

    2015-01-01

    Highlights: • Current–voltage characteristics of two polymeric junctions are studied. • Current is reduced in phonon assistant tunneling regime. • Behavior of current is independent of temperature. • Elastic energy changes current drastically. - Abstract: The inelastic electron transport properties through two polymeric (trans-polyacetylene and polythiophene) molecular junctions are studied using Keldysh nonequilibrium Green function formalism. The Hamiltonian of the polymers is described via Su–Schrieffer–Heeger model and the metallic electrodes are modeled by the wide-band approximation. Results show that the step-like behavior of the current–voltage characteristics is deformed in presence of strong electron–phonon interaction. Also, the magnitude of current is slightly decreased in the phonon assistant electron transport regime. In addition, it is observed that the I–V curves are independent of temperature

  8. A new lithography of functional plasma polymerized thin films

    International Nuclear Information System (INIS)

    Kim, Sung-O

    2001-01-01

    The preparation of the resist for the vacuum lithography was carried out by plasma polymerization. The resist manufactured by plasma polymerization is a monomer produced by MMA (Methyl methacrylate). The functional groups of MMA appeared in the PPMMA (Plasma Polymerized Methyl methacrylate) as well, and this was confirmed through an analysis using FT-IR. The polymerization rate increased as a function of the plasma power and decreased as a function of the system pressure. The sensitivity and contrast of the plasma polymerized thin films were 15 μC/cm2 and 4.3 respectively. The size of the pattern manufactured by Vacuum Lithography using the plasma polymerized thin films was 100 nm

  9. Measurement and Analysis of in vitro Actin Polymerization

    Science.gov (United States)

    Doolittle, Lynda K.; Rosen, Michael K.; Padrick, Shae B.

    2014-01-01

    Summary The polymerization of actin underlies force generation in numerous cellular processes. While actin polymerization can occur spontaneously, cells maintain control over this important process by preventing actin filament nucleation and then allowing stimulated polymerization and elongation by several regulated factors. Actin polymerization, regulated nucleation and controlled elongation activities can be reconstituted in vitro, and used to probe the signaling cascades cells use to control when and where actin polymerization occurs. Introducing a pyrene fluorophore allows detection of filament formation by an increase in pyrene fluorescence. This method has been used for many years and continues to be broadly used, owing to its simplicity and flexibility. Here we describe how to perform and analyze these in vitro actin polymerization assays, with an emphasis on extracting useful descriptive parameters from kinetic data. PMID:23868594

  10. Strong, tough and stiff bioinspired ceramics from brittle constituents

    Science.gov (United States)

    Bouville, Florian; Maire, Eric; Meille, Sylvain; van de Moortèle, Bertrand; Stevenson, Adam J.; Deville, Sylvain

    2014-05-01

    High strength and high toughness are usually mutually exclusive in engineering materials. In ceramics, improving toughness usually relies on the introduction of a metallic or polymeric ductile phase, but this decreases the material’s strength and stiffness as well as its high-temperature stability. Although natural materials that are both strong and tough rely on a combination of mechanisms operating at different length scales, the relevant structures have been extremely difficult to replicate. Here, we report a bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (22 MPa m1/2), and high stiffness (290 GPa). Because only mineral constituents are needed, these ceramics retain their mechanical properties at high temperatures (600 °C). Our bioinspired, material-independent approach should find uses in the design and processing of materials for structural, transportation and energy-related applications.

  11. Polypropylene/graphite nanocomposites by in situ polymerization

    International Nuclear Information System (INIS)

    Milani, Marceo A.; Galland, Giselda B.; Quijada, Raul

    2011-01-01

    This work presents the synthesis of nanocomposites of polypropylene/graphite by in situ polymerization using metallocene catalyst and graphene nanosheets. Initially was analyzed which of the metallocene catalysts rac-Et(Ind) 2 ZrCl 2 or rac-Me 2 Si(Ind) 2 ZrCl 2 produces polypropylene with mechanical properties more relevant. Then it were performed the in situ polymerization reactions to obtain the nanocomposites. The polymeric materials were characterized by XRD, DSC, GPC and DMTA. (author)

  12. Investigations in the field of solid state polymerization Pt. 38

    International Nuclear Information System (INIS)

    Hardy, Gy.; Cser, F.; Nyitrai, K.; Fedorova, N.

    1980-01-01

    The stuctural and radiation chemical data of vinyl monomers with long chain paraffinic or cholesteric side groups are critically reviewed. Based on their structural and polymerization kinetical characteristics the monomers may be classified into three groups. Oblique layers are favourable for homogeneous topotactic polymerization. This is characterized by a low activation energy and a radiochemical efficiency very similar to that measured in liquid state polymerization. The tilted layers are not favourable for homogeneous topotactic polymerization. Allyl monomers yield polymers with higher molecular weights in the layer structure than in liquid states. (author)

  13. Nanoporous Polymeric Grating-Based Optical Biosensors (Preprint)

    National Research Council Canada - National Science Library

    Hsiao, Vincent K; Waldeisen, John R; Lloyd, Pamela F; Bunning, Timothy J; Huang, Tony J

    2007-01-01

    .... The fabrication process of the nanoporous polymeric grating involves holographic interference patterning and a functionalized pre-polymer syrup that facilitates the immobilization of biomolecules...

  14. Biocompatible Polymeric Materials Intended for Drug Delivery and Therapeutic Applications

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Javakhishvili, Irakli; Bednarek, Melania

    2007-01-01

    of polymer blocks by “click chemistry”. An all polymerization strategy would imply preparing polymers by living/controlled techniques in such a manner that one block after polymerization can be converted to a macroinitiator enabling the second block to polymerize. The coupling strategy invariably inserts...... a linking unit, 1,4-triazol, resulting from the catalyzed, irreversible 1,3-dipolar cycloaddition reaction between an alkyne and an azide. Thus, this strategy necessitates the proper end functionalization of the polymeric building blocks. Fortunately the 1,4-triazol unit is FDA approved already existing...

  15. Online observation of emulsion polymerization by fluorescence technique

    CERN Document Server

    Rudschuck, S; Fuhrmann, J

    1999-01-01

    An online observation of local polarity via fluorescence spectroscopy was used to study the formation and growth of polymer particles during an emulsifier-free heterogeneous polymerization. The reaction mixture consisted of styrene dispersed in water and the polymerization was initiated by a macro-initiator (hydrolyzed propene-maleic acid copolymer with t-butyl perester groups). Pyrenyl probes were attached to the backbone of the initiator to analyze the heterogeneous reaction. The experimental results allow a clear distinction of different time regions during the heterogeneous polymerization. Information about the heating period, the latex formation, the particle growth and the final stage of the polymerization process (gel point) were obtained. (11 refs).

  16. Strongly Correlated Systems Theoretical Methods

    CERN Document Server

    Avella, Adolfo

    2012-01-01

    The volume presents, for the very first time, an exhaustive collection of those modern theoretical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciates consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as po...

  17. Strongly correlated systems numerical methods

    CERN Document Server

    Mancini, Ferdinando

    2013-01-01

    This volume presents, for the very first time, an exhaustive collection of those modern numerical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and material science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciate consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possi...

  18. Strongly correlated systems experimental techniques

    CERN Document Server

    Mancini, Ferdinando

    2015-01-01

    The continuous evolution and development of experimental techniques is at the basis of any fundamental achievement in modern physics. Strongly correlated systems (SCS), more than any other, need to be investigated through the greatest variety of experimental techniques in order to unveil and crosscheck the numerous and puzzling anomalous behaviors characterizing them. The study of SCS fostered the improvement of many old experimental techniques, but also the advent of many new ones just invented in order to analyze the complex behaviors of these systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. The volume presents a representative collection of the modern experimental techniques specifically tailored for the analysis of strongly correlated systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognize...

  19. Flavour Democracy in Strong Unification

    CERN Document Server

    Abel, S A; Abel, Steven; King, Steven

    1998-01-01

    We show that the fermion mass spectrum may naturally be understood in terms of flavour democratic fixed points in supersymmetric theories which have a large domain of attraction in the presence of "strong unification". Our approach provides an alternative to the approximate Yukawa texture zeroes of the Froggatt-Nielsen mechanism. We discuss a particular model based on a broken gauged $SU(3)_L\\times SU(3)_R$ family symmetry which illustrates our approach.

  20. Resveratrol immobilization and release in polymeric hydrogels

    International Nuclear Information System (INIS)

    Momesso, Roberta Grazzielli Ramos Alves Passarelli

    2010-01-01

    Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)