Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents

Science.gov (United States)

Pappas, S. P.; Hsiao, Y. C.; Hill, L. W.

1973-01-01

Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided.

Novel silicone-based polymer containing active methylene designed for the removal of indoor formaldehyde

Energy Technology Data Exchange (ETDEWEB)

Niu, Song, E-mail: niusong84@163.com; Yan, Hongxia, E-mail: hongxiayan@nwpu.edu.cn

2015-04-28

Highlights: • A novel silicone-based polymer with active methylene was explored. • Surface tension of liquid paints could be lowered using the polymer. • The polymer was easy to migrate toward the air-coating interface. • Free HCHO could effectively be removed using the polymer. • A lights on HCHO reduction without complicated preparation procedure was shielded. - Abstract: Indoor air pollution is caused inevitably due to complicated home decoration, in which formaldehyde is one of the most typical pollutants. It will be a convenient, economical and effective strategy to remove indoor formaldehyde if imparting a feature of formaldehyde removal to decorative coatings. We have successfully explored a novel silicone-based polymer containing active methylene used as a formaldehyde absorbent in coatings via a straightforward transesterification process using inexpensive and easily available chemicals. The polymer has been characterized by {sup 13}C NMR, FTIR, GC and GPC. Formaldehyde removal capacity of the coating films containing different contents of the polymer has been investigated. The results indicated that coatings incorporating 4 wt% of the polymer could make the coating films exhibit significant improvement on formaldehyde removal including purificatory performance (>85%) and durability of purificatory effect (>60%), compared to those consisting of absorbents without any silicon, and improve yellowing resistance performance, while other properties, such as gloss, adhesion, pencil hardness, flexibility and impact resistance, were kept almost unaffected. The chemical absorption process of the silicone-based polymer filled in interior decorative coatings is demonstrated as a promising technology to purify indoor formaldehyde and thus can reduce the harm to individuals.

Synchrotron radiation total reflection x-ray fluorescence analysis; of polymer coated silicon wafers

International Nuclear Information System (INIS)

Brehm, L.; Kregsamer, P.; Pianetta, P.

2000-01-01

It is well known that total reflection x-ray fluorescence (TXRF) provides an efficient method for analyzing trace metal contamination on silicon wafer surfaces. New polymeric materials used as interlayer dielectrics in microprocessors are applied to the surface of silicon wafers by a spin-coating process. Analysis of these polymer coated wafers present a new challenge for TXRF analysis. Polymer solutions are typically analyzed for bulk metal contamination prior to application on the wafer using inductively coupled plasma mass spectrometry (ICP-MS). Questions have arisen about how to relate results of surface contamination analysis (TXRF) of a polymer coated wafer to bulk trace analysis (ICP-MS) of the polymer solutions. Experiments were done to explore this issue using synchrotron radiation (SR) TXRF. Polymer solutions were spiked with several different concentrations of metals. These solutions were applied to silicon wafers using the normal spin-coating process. The polymer coated wafers were then measured using the SR-TXRF instrument set-up at the Stanford Synchrotron Radiation Laboratory (SSRL). Several methods of quantitation were evaluated. The best results were obtained by developing calibration curves (intensity versus ppb) using the spiked polymer coated wafers as standards. Conversion of SR-TXRF surface analysis results (atoms/cm 2 ) to a volume related concentration was also investigated. (author)

Property control of graphene aerogels by in situ growth of silicone polymer

Science.gov (United States)

Zhou, Shuai; Zhou, Xiang; Hao, Gazi; Jiang, Wei; Wang, Tianhe

2018-05-01

Modulation of the density (from 3.5 to 64 mg cm-3), hydrophobicity and oil-uptake capability of graphene aerogels in extensive ranges were achieved by reacting (3-Mercaptopropyl)trimethoxysilane (MPS) with graphene oxide solutions under heating. The reaction allowed a characteristic silicone substructure to be formed on graphene and joint the graphene layers firmly together. With the increase of MPS concentrations (≤ca. 0.2 vol%), the nano silicone polymer grown on graphene functioned as a "linker" and "spacer", leading to a substantial decrease of the aerogel density. Because of the formation of silicone polymer and the characteristic nano-micro substructures on the backbones of graphene aerogels, the graphene aerogels exhibited a high hydrophobicity with the water contact angle consistently exceeding 142 degrees. Functionalized graphene aerogels with a density of 3.5 mg cm-3 were conveniently fabricated that displayed an extraordinary oil absorption capacity, 182 times for lubricating oil and 143 times for n-hexane of its own weight. Furthermore, the aerogels maintained their ultra-high absorption capability even after 20 absorption-distillation cycles, due to structural integrity held by the strong interfacial adhesion between graphene sheets and polymer chains of aerogels. This study offers a promising graphene aerogels and also provides a strategy for fabricating extra low dense functional materials.

Functionalization of silicon nanowires by conductive and non-conductive polymers

Science.gov (United States)

Belhousse, S.; Tighilt, F.-Z.; Sam, S.; Lasmi, K.; Hamdani, K.; Tahanout, L.; Megherbi, F.; Gabouze, N.

2017-11-01

The work reports on the development of hybrid devices based on silicon nanowires (SiNW) with polymers and the difference obtained when using conductive and non-conductive polymers. SiNW have attracted much attention due to their importance in understanding the fundamental properties at low dimensionality as well as their potential application in nanoscale devices as in field effect transistors, chemical or biological sensors, battery electrodes and photovoltaics. SiNW arrays were formed using metal assisted chemical etching method. This process is simple, fast and allows obtaining a wide range of silicon nanostructures. Hydrogen-passivated SiNW surfaces show relatively poor stability. Surface modification with organic species confers the desired stability and enhances the surface properties. For this reason, this work proposes a covalent grafting of organic material onto SiNW surface. We have chosen a non-conductive polymer polyvinylpyrrolidone (PVP) and conductive polymers polythiophene (PTh) and polypyrrole (PPy), in order to evaluate the electric effect of the polymers on the obtained materials. The hybrid structures were elaborated by the polymerization of the corresponding conjugated monomers by electrochemical route; this electropolymerization offers several advantages such as simplicity and rapidity. SiNW functionalization by conductive polymers has shown to have a huge effect on the electrical mobility. Hybrid surface morphologies were characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR-ATR) and contact angle measurements.

Direct Production of Silicones From Sand

Energy Technology Data Exchange (ETDEWEB)

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30

Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

Synthesis and study of novel silicon-based unsaturated polymers

Energy Technology Data Exchange (ETDEWEB)

Lin, Jibing [Iowa State Univ., Ames, IA (United States)

1995-06-19

Novel unsaturated polymers have been synthesized and studied as precursors to silicon carbide and third order nonlinear optical materials. X ray structures were obtained. Kinetic and mechanistic studies of the unique thermal isomerization of dimethylenedisilacyclobutane to a carbene were conducted.

Soft contact lens biomaterials from bioinspired phospholipid polymers.

Science.gov (United States)

Goda, Tatsuro; Ishihara, Kazuhiko

2006-03-01

Soft contact lens (SCL) biomaterials originated from the discovery of a poly(2-hydroxyethyl methacrylate) (poly[HEMA])-based hydrogel in 1960. Incorporation of hydrophilic polymers into poly(HEMA) hydrogels was performed in the 1970-1980s, which brought an increase in the equilibrium water content, leading to an enhancement of the oxygen permeability. Nowadays, the poly(HEMA)-based hydrogels have been applied in disposable SCL. At the same time, high oxygen-permeable silicone hydrogels were produced, which made it possible to continually wear SCL. Recently, numerous trials for improving the water wettability of silicone hydrogels have been performed. However, little attention has been paid to improving their anti-biofouling properties and biocompatibility. Since biomimetic phospholipid polymers possess excellent anti-biofouling properties and biocompatibility they have the potential to play a valuable role in the surface modification of the silicone hydrogel. The representative phospholipid polymers containing a 2-methacryloyloxyethyl phosphorylcholine (MPC) unit suppressed nonspecific protein adsorption, increased cell compatibility and contributed to blood compatible biomaterials. The MPC polymer coating on the silicone hydrogel improved its water wettability and biocompatibility, while maintaining high oxygen permeability compared with the original silicone hydrogel. Furthermore, the newly prepared phospholipid-type intermolecular crosslinker made it possible to synthesize a 100% phospholipid polymer hydrogel that can enhance the anti-biofouling properties and biocompatibility. In this review, the authors discuss how polymer hydrogels should be designed in order to obtain a biocompatible SCL and future perspectives.

Broadband and scalable optical coupling for silicon photonics using polymer waveguides

Science.gov (United States)

La Porta, Antonio; Weiss, Jonas; Dangel, Roger; Jubin, Daniel; Meier, Norbert; Horst, Folkert; Offrein, Bert Jan

2018-04-01

We present optical coupling schemes for silicon integrated photonics circuits that account for the challenges in large-scale data processing systems such as those used for emerging big data workloads. Our waveguide based approach allows to optimally exploit the on-chip optical feature size, and chip- and package real-estate. It further scales well to high numbers of channels and is compatible with state-of-the-art flip-chip die packaging. We demonstrate silicon waveguide to polymer waveguide coupling losses below 1.5 dB for both the O- and C-bands with a polarisation dependent loss of <1 dB. Over 100 optical silicon waveguide to polymer waveguide interfaces were assembled within a single alignment step, resulting in a physical I/O channel density of up to 13 waveguides per millimetre along the chip-edge, with an average coupling loss of below 3.4 dB measured at 1310 nm.

Synthesis and characterization of UV-absorbing fluorine-silicone acrylic resin polymer

Science.gov (United States)

Lei, Huibin; He, Deliang; Guo, Yanni; Tang, Yining; Huang, Houqiang

2018-06-01

A series of UV-absorbing fluorine-silicone acrylic resin polymers containing different amount of UV-absorbent were successfully prepared by solution polymerization, with 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate (BHEM), vinyltrimethoxysilane (VTMS) and hexafluorobutyl methacrylate (HFMA) as modifying monomers. The acrylic polymers and the coatings thereof were characterized by Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) absorption spectrum, thermogravimetric analysis (TGA), water contact angle (CA) and Xenon lamp artificial accelerated aging tests. Results indicated that the resin exhibited high UV absorption performance as well as good thermal stability. The hydrophobicity of the coatings was of great improvement because of the bonded fluorine and silicone. Meanwhile, the weather-resistance was promoted through preferably colligating the protective effects of BHEM, organic fluorine and silicone. Also, a fitting formula about the weatherability with the BMHE content was tentatively proposed.

Non-Vacuum Processed Polymer Composite Antireflection Coating Films for Silicon Solar Cells

Directory of Open Access Journals (Sweden)

Abdullah Uzum

2016-08-01

Full Text Available A non-vacuum processing method for preparing polymer-based ZrO2/TiO2 multilayer structure antireflection coating (ARC films for crystalline silicon solar cells by spin coating is introduced. Initially, ZrO2, TiO2 and surface deactivated-TiO2 (SD-TiO2 based films were examined separately and the effect of photocatalytic properties of TiO2 film on the reflectivity on silicon surface was investigated. Degradation of the reflectance performance with increasing reflectivity of up to 2% in the ultraviolet region was confirmed. No significant change of the reflectance was observed when utilizing SD-TiO2 and ZrO2 films. Average reflectance (between 300 nm–1100 nm of the silicon surface coated with optimized polymer-based ZrO2 single or ZrO2/SD-TiO2 multilayer composite films was decreased down to 6.5% and 5.5%, respectively. Improvement of photocurrent density (Jsc and conversion efficiency (η of fabricated silicon solar cells owing to the ZrO2/SD-TiO2 multilayer ARC could be confirmed. The photovoltaic properties of Jsc, the open-circuit photo voltage (VOC, the fill factor (FF, and the η were 31.42 mA cm−2, 575 mV, 71.5% and 12.91%. Efficiency of the solar cells was improved by the ZrO2-polymer/SD-TiO2 polymer ARC composite layer by a factor of 0.8% with an increase of Jsc (2.07 mA cm−2 compared to those of fabricated without the ARC.

Structural symmetry breaking of silicon containing polymers and their relation with electrical conductivity and Raman active vibrations

Science.gov (United States)

Cabrera, Alejandro; González, Carmen; Tagle, Luis; Terraza, Claudio; Volkmann, Ulrich; Barriga, Andrés; Ramos, Esteban; Pavez, Maximiliano

2011-03-01

The incorporation of silicon into the polymeric main chain or side groups can provide an enhancement in chemical, physical and mechanical properties. We report an efficient method for the synthesis of polymers containing silicon in the main chain, from the polycondensation reactions of four optically active carboxylic diacid. The solubility of the polymers, the molecular weight, the glass transition and the thermal stability were studied by standard techniques. Raman spectroscopy was used to probe the conformation of stretching modes as function of the temperature. The conductivity measurements indicated that the alignment of the molecules is a crucial parameter for electrical performance. When the polymers were exposed to iodine, charge transfer increased their mobility and decreased their optical band gaps. These novel properties highlight the possibility to generate alternative active opto-electronics polymers.

Synthesis and characterisation of star polymer/silicon carbide nanocomposites

International Nuclear Information System (INIS)

Majewski, Peter; Choudhury, Namita Roy; Spori, Doris; Wohlfahrt, Ellen; Wohlschloegel, Markus

2006-01-01

A new type of composite material's preparation and property are reported in this paper. The composite was formed by solution blending a styrene ethylene butylenes (SEBS) star polymer with silicon carbide at various compositions. The composites were characterised using spectroscopic, microscopic and thermal techniques. Photo-acoustic Fourier transform infrared spectroscopy (PA-FT-IR) and transmission electron microscopy (TEM) results show that the SiC resides uniformly in the organic network. Thermogravimetric analysis (TGA) of the hybrid shows that the thermal stability of the composite is higher than that of the star polymer. The maximum decomposition temperature increases by 73 deg. C. Dynamic mechanical analysis (DMA) of the hybrid shows that the storage modulus of the star polymer increases after the composite formation, indicating the existence of thermodynamically stable SiC nanoparticles mostly in the micro-phase separated multiarm structure of the polymer

Method and apparatus for evaluating structural weakness in polymer matrix composites

Science.gov (United States)

Wachter, Eric A.; Fisher, Walter G.

1996-01-01

A method and apparatus for evaluating structural weaknesses in polymer matrix composites is described. An object to be studied is illuminated with laser radiation and fluorescence emanating therefrom is collected and filtered. The fluorescence is then imaged and the image is studied to determine fluorescence intensity over the surface of the object being studied and the wavelength of maximum fluorescent intensity. Such images provide a map of the structural integrity of the part being studied and weaknesses, particularly weaknesses created by exposure of the object to heat, are readily visible in the image.

Diorganosilacetylene-alt-diorganosilvinylene polymers and a process densifying porous silicon-carbide bodies

Science.gov (United States)

Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

1994-05-17

The present invention provides linear organosilicon polymers including acetylene and vinylene moieties, and a process for their preparation. These diorganosilacetylene-alt-diorganosilvinylene linear polymers can be represented by the formula: --[--(R.sup.1)(R.sup.2)Si--C.tbd.C--(R.sup.3)(R.sup.4)Si--CH=CH--].sub.n-- , wherein n.gtoreq.2; and each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, aryl, and aralkyl radicals. The polymers are soluble in organic solvents, air stable, and can be pulled into fibers or cast into films. They can be thermally converted into silicon carbide ceramic materials.

On electronic structure of polymer-derived amorphous silicon carbide ceramics

Science.gov (United States)

Wang, Kewei; Li, Xuqin; Ma, Baisheng; Wang, Yiguang; Zhang, Ligong; An, Linan

2014-06-01

The electronic structure of polymer-derived amorphous silicon carbide ceramics was studied by combining measurements of temperature-dependent conductivity and optical absorption. By comparing the experimental results to theoretical models, electronic structure was constructed for a carbon-rich amorphous silicon carbide, which revealed several unique features, such as deep defect energy level, wide band-tail band, and overlap between the band-tail band and defect level. These unique features were discussed in terms of the microstructure of the material and used to explain the electric behavior.

Growing Embossed Nanostructures of Polymer Brushes on Wet-Etched Silicon Templated via Block Copolymers

Science.gov (United States)

Lu, Xiaobin; Yan, Qin; Ma, Yinzhou; Guo, Xin; Xiao, Shou-Jun

2016-02-01

Block copolymer nanolithography has attracted enormous interest in chip technologies, such as integrated silicon chips and biochips, due to its large-scale and mass production of uniform patterns. We further modified this technology to grow embossed nanodots, nanorods, and nanofingerprints of polymer brushes on silicon from their corresponding wet-etched nanostructures covered with pendent SiHx (X = 1-3) species. Atomic force microscopy (AFM) was used to image the topomorphologies, and multiple transmission-reflection infrared spectroscopy (MTR-IR) was used to monitor the surface molecular films in each step for the sequential stepwise reactions. In addition, two layers of polymethacrylic acid (PMAA) brush nanodots were observed, which were attributed to the circumferential convergence growth and the diffusion-limited growth of the polymer brushes. The pH response of PMAA nanodots in the same region was investigated by AFM from pH 3.0 to 9.0.

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

International Nuclear Information System (INIS)

Liu, Pingsheng; Chen, Qiang; Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong; Shen, Jian

2013-01-01

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

Energy Technology Data Exchange (ETDEWEB)

Liu, Pingsheng [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen, Qiang, E-mail: chem100@nju.edu.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); High Technology Research Institute of Nanjing University, Changzhou 213164 (China); Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Shen, Jian, E-mail: shenj1957@yahoo.com.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

2013-10-15

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical.

Kinetic Assembly of Near-IR Active Gold Nanoclusters using Weakly Adsorbing Polymers to Control Size

Science.gov (United States)

Tam, Jasmine M.; Murthy, Avinash K.; Ingram, Davis R.; Nguyen, Robin; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

Clusters of metal nanoparticles with an overall size less than 100 nm and high metal loadings for strong optical functionality, are of interest in various fields including microelectronics, sensors, optoelectronics and biomedical imaging and therapeutics. Herein we assemble ~5 nm gold particles into clusters with controlled size, as small as 30 nm and up to 100 nm, which contain only small amounts of polymeric stabilizers. The assembly is kinetically controlled with weakly adsorbing polymers, PLA(2K)-b-PEG(10K)-b-PLA(2K) or PEG (MW = 3350), by manipulating electrostatic, van der Waals (VDW), steric, and depletion forces. The cluster size and optical properties are tuned as a function of particle volume fractions and polymer/gold ratios to modulate the interparticle interactions. The close spacing between the constituent gold nanoparticles and high gold loadings (80–85% w/w gold) produce a strong absorbance cross section of ~9×10−15 m2 in the NIR at 700 nm. This morphology results from VDW and depletion attractive interactions that exclude the weakly adsorbed polymeric stabilizer from the cluster interior. The generality of this kinetic assembly platform is demonstrated for gold nanoparticles with a range of surface charges from highly negative to neutral, with the two different polymers. PMID:20361735

End-functional silicone coupling agent modified PEO/P(VDF-HFP)/SiO2 nanocomposite polymer electrolyte DSSC

International Nuclear Information System (INIS)

Zhang Jing; Yang Ying; Wu Sujuan; Xu Sheng; Zhou Conghua; Hu Hao; Chen Bolei; Xiong Xiaodong; Sebo, Bobby; Han Hongwei; Zhao Xingzhong

2008-01-01

The end-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS for short) was used to modify the PEO/P(VDF-HFP)/SiO 2 nanocomposite polymer electrolyte (CPE) and the different amounts of DTMS modification effects were studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains (-C 12 H 25 ) chemically engineered on the SiO 2 nanoparticles, and formed a Si-O-Si cross-linked network in the new nanocomposite polymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionic conductivity and the connection with the photoanode and counter electrode. However, much higher content of the DTMS modification changed the conformation of the polymer network and reduced the ionic movement. Compared with the performance (3.84%) of the original DSSC, the DSSC with functional silicone coupling agent modified CPE (DTMS:SiO 2 = 2:1, mol ratio) exhibited improved J sc (7.94 mA cm -2 ), V oc (0.624 V) and optimal efficiency (5.2%) (measured at AM1.5, light intensity of 58.4 mW cm -2 ). The V oc of the silicone coupling agent modified polymer electrolyte DSSC is obviously improved, which is mainly due to that the hydrophobic alkyl chain end groups formed an insulating layer that retarded the electron recombination at the TiO 2 nanoporous photoanode/polymer electrolyte interface. The DTMS:SiO 2 = 2:1 modified CPE type DSSC exhibited a performance of 6.42% at a light intensity of 32.1 mW cm -2 and 4.94% at 99.2 mW cm -2

A low cost and hybrid technology for integrating silicon sensors or actuators in polymer microfluidic systems

International Nuclear Information System (INIS)

Charlot, Samuel; Gué, Anne-Marie; Tasselli, Josiane; Marty, Antoine; Abgrall, Patrick; Estève, Daniel

2008-01-01

This paper describes a new technology permitting a hybrid integration of silicon chips in polymer (PDMS and SU8) microfluidic structures. This two-step technology starts with transferring the silicon device onto a rigid substrate (typically PCB) and planarizing it, and then it proceeds with stacking of the polymer-made fluidic network onto the device. The technology is low cost, based on screen printing and lamination, can be applied to treat large surface areas, and is compatible with standard photolithography and vacuum based approaches. We show, as an example, the integration of a thermal sensor inside channels made of PDMS or SU8. The developed structures had no fluid leaks at the Si/polymer interfaces and the electrical circuit was perfectly tightproof. (note)

Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

International Nuclear Information System (INIS)

Ben Dkhil, S.; Bourguiga, R.; Davenas, J.; Cornu, D.

2012-01-01

Highlights: ► Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. ► We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. ► The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. ► We have investigated the effects of SiNWs concentration on the photovoltaic characteristics leading to the optimization of a critical SiNWs concentration. - Abstract: Hybrid thin films combining the high optical absorption of a semiconducting polymer film and the electronic properties of silicon fillers have been investigated in the perspective of the development of low cost solar cells. Bulk heterojunction photovoltaic materials based on blends of a semiconductor polymer poly(N-vinylcarbazole) (PVK) as electron donor and silicon nanowires (SiNWs) as electron acceptor have been studied. Composite PVK/SiNWs films were cast from a common solvent mixture. UV–visible spectrometry and photoluminescence of the composites have been studied as a function of the SiNWs concentration. Photoluminescence spectroscopy (PL) shows the existence of a critical SiNWs concentration of about 10 wt % for PL quenching corresponding to the most efficient charge pair separation. The photovoltaic (PV) effect has been studied under illumination. The optimum open-circuit voltage V oc and short-circuit current density J sc are obtained for 10 wt % SiNWs whereas a degradation of these parameters is observed at higher SiNWs concentrations. These results are correlated to the formation of aggregates in the composite leading to recombination of the photogenerated charge pairs competing with the dissociation mechanism.

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Rijn, van C.J.M.; Zuilhof, H.

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, Ai T.; Baggerman, Jacob; Paulusse, Jos Marie Johannes; van Rijn, Cees J.M.; Zuilhof, Han

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable Si−C

Orientation of One-Dimensional Silicon Polymer Films Studied by X-Ray Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

Md. Abdul Mannan

2012-01-01

Full Text Available Molecular orientations for thin films of one-dimensional silicon polymers grown by vacuum evaporation have been assigned by near-edge X-ray absorption fine structure (NEXAFS using linearly polarized synchrotron radiation. The polymer investigated was polydimethylsilane (PDMS which is the simplest stable silicon polymer, and one of the candidate materials for one-dimensional molecular wire. For PDMS films deposited on highly oriented pyrolytic graphite (HOPG, four resonance peaks have been identified in the Si K-edge NEXAFS spectra. Among these peaks, the intensities of the two peaks lower-energy at 1842.0 eV and 1843.2 eV were found to be strongly polarization dependent. The peaks are assigned to the resonance excitations from the Si 1s to σ∗ pyz and σ∗ px orbitals localized at the Si–C and Si–Si bonds, respectively. Quantitative evaluation of the polarization dependence of the NEXAFS spectra revealed that the molecules are self-assembled on HOPG surface, and the backbones of the PDMS are oriented nearly parallel to the surface. The observed orientation is opposite to the previously observed results for PDMS on the other surfaces such as oxide (indium tin oxide and metal (polycrystalline copper. The flat-lying feature of PDMS observed only on HOPG surface is attributed to the interaction between CH bonds in PDMS and π orbitals in HOPG surface.

Finite element modelling and experimental characterization of an electro-thermally actuated silicon-polymer micro gripper

International Nuclear Information System (INIS)

Krecinic, F; Duc, T Chu; Sarro, P M; Lau, G K

2008-01-01

This paper presents simulation and experimental characterization of an electro-thermally actuated micro gripper. This micro actuator can conceptually be seen as a bi-morph structure of SU-8 and silicon, actuated by thermal expansion of the polymer. The polymer micro gripper with an embedded comb-like silicon skeleton is designed to reduce unwanted out-of-plane bending of the actuator, while offering a large gripper stroke. The temperature and displacement field of the micro gripper structure is determined using a two-dimensional finite element analysis. This analysis is compared to experimental data from steady-state and transient measurements of the integrated heater resistance, which depends on the average temperature of the actuator. The stability of the polymer actuator is evaluated by recording the transient behaviour of the actual jaw displacements. The maximum single jaw displacement of this micro gripper design is 34 µm at a driving voltage of 4 V and an average actuator temperature of 170 °C. The transient thermal response is modelled by a first-order system with a characteristic time constant of 11.1 ms. The simulated force capability of the device is 0.57 mN per µm jaw displacement

Solubility of gases and solvents in silicon polymers: molecular simulation and equation of state modeling

DEFF Research Database (Denmark)

Economou, Ioannis; Makrodimitri, Zoi A.; Kontogeorgis, Georgios

2007-01-01

of gas and solvent solubilities using the test particle insertion method of Widom. Polymer chains are modelled using recently developed realistic atomistic force fields. Calculations are performed at various temperatures and ambient pressure. A crossover in the temperature dependence of solubility......) and also the phase equilibria of these mixtures over a wide composition range. In all cases, the agreement between model predictions/correlations and literature experimental data, when available, is excellent.......The solubility of n-alkanes, perfluoroalkanes, noble gases and light gases in four elastomer polymers containing silicon is examined based on molecular simulation and macroscopic equation of state modelling. Polymer melt samples generated from molecular dynamics ( MD) are used for the calculation...

Hybrid nanocomposites based on conducting polymer and silicon nanowires for photovoltaic application

International Nuclear Information System (INIS)

Chehata, Nadia; Ltaief, Adnen; Ilahi, Bouraoui; Salem, Bassem; Bouazizi, Abdelaziz; Maaref, Hassen; Baron, Thierry

2014-01-01

Hybrid nanocomposites based on a nanoscale combination of organic and inorganic semiconductors are a promising way to enhance the performance of solar cells through a higher aspect ratio of the interface and the good processability of polymers. Nanocomposites are based on a heterojunction network between poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) as an organic electron donor and silicon nanowires (SiNWs) as an inorganic electron acceptor. Nanowires (NWs) seem to be a promising material for this purpose, as they provide a large surface area for contact with the polymer and a designated conducting pathway whilst their volume is low. In this paper, silicon nanowires are introduced by mixing them into the polymer matrix. Hybrid nanocomposites films were deposited onto ITO substrate by spin coating method. Optical properties and photocurrent response were investigated. Charge transfer between the polymer and SiNWs has been demonstrated through photoluminescence measurements. The photocurrent density of ITO/MEH-PPV:SiNWs/Al structures have been obtained by J–V characteristics. The J sc value is about 0.39 µA/cm 2 . - Highlights: • SiNWs synthesis by Vapor–Liquid–Solid (VLS) mechanism. • SiNWs contribution to absorption spectra enhancement of MEH-PPV:SiNWs nanocomposites. • Decrease of PL intensity of MEH-PPV by addition of SiNWs. • Charge transfer process was taken place. • ITO/MEH-PPV:SiNWs/Al structure shows a photovoltaic effect, with a FF of 0.32

Polymer-Derived Silicon Oxycarbide Ceramics as Promising Next-Generation Sustainable Thermoelectrics.

Science.gov (United States)

Kousaalya, Adhimoolam Bakthavachalam; Zeng, Xiaoyu; Karakaya, Mehmet; Tritt, Terry; Pilla, Srikanth; Rao, Apparao M

2018-01-24

We demonstrate the potential of polymer-derived ceramics (PDC) as next-generation sustainable thermoelectrics. Thermoelectric behavior of polymer-derived silicon oxycarbide (SiOC) ceramics (containing hexagonal boron nitride (h-BN) as filler) was studied as a function of measurement temperature. SiOC, sintered at 1300 °C exhibited invariant low thermal conductivity (∼1.5 W/(m·K)) over 30-600 °C, coupled with a small increase in both Seebeck coefficient and electrical conductivity, with increase in measurement temperature (30-150 °C). SiOC ceramics containing 1 wt % h-BN showed the highest Seebeck coefficient (-33 μV/K) for any PDC thus far.

High yield silicon carbide from alkylated or arylated pre-ceramic polymer

International Nuclear Information System (INIS)

Baney, R.H.; Gaul, J.H.

1982-01-01

Alkylated or arylated methylpolysilanes which exhibit ease of handling and are used to obtain silicon carbide ceramic materials in high yields contain 0 to 60 mole percent (CH 3 ) 2 Si double bond units and 40 to 100 mole percent CH 3 Si triple bond units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl. They may be prepared by reaction of a Grignard reagent RMgX, where X is halogen and R is Csub(1-4)-alkyl or phenyl, with a starting material which is a solid at 25 0 C, and is identical to the product except that the remaining bonds on the silicon atoms are attached to another silicon atom, or a chlorine or a bromine atom. Ceramics result from heating the polysilane products to 1200 0 C, optionally with fillers. (author)

Soft hydrogels interpenetrating silicone – a polymer network for drug releasing medical devices

DEFF Research Database (Denmark)

Steffensen, Søren Langer; Merete H., Vestergaard,; Møller, Eva Horn

2016-01-01

such a sophisticated material by forming an interpenetrating polymer network (IPN) material through modification of silicone elastomers with a poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogel. IPN materials with a PHEMA content in the range of 13%–38% (w/w) were synthesized by using carbon dioxide...

Modification of inkjet printer for polymer sensitive layer preparation on silicon-based gas sensors

Directory of Open Access Journals (Sweden)

Tianjian Li

2015-04-01

Full Text Available Inkjet printing is a versatile, low cost deposition technology with the capabilities for the localized deposition of high precision, patterned deposition in a programmable way, and the parallel deposition of a variety of materials. This paper demonstrates a new method of modifying the consumer inkjet printer to prepare polymer-sensitive layers on silicon wafer for gas sensor applications. A special printing tray for the modified inkjet printer to support a 4-inch silicon wafer is designed. The positioning accuracy of the deposition system is tested, based on the newly modified printer. The experimental data show that the positioning errors in the horizontal direction are negligibly small, while the positioning errors in the vertical direction rise with the increase of the printing distance of the wafer. The method for making suitable ink to be deposited to form the polymer-sensitive layer is also discussed. In the testing, a solution of 0.1 wt% polyvinyl alcohol (PVA was used as ink to prepare a sensitive layer with certain dimensions at a specific location on the surface of the silicon wafer, and the results prove the feasibility of the methods presented in this article.

Hydrogen diffusion between plasma-deposited silicon nitride-polyimide polymer interfaces

International Nuclear Information System (INIS)

Nguyen, S.V.; Kerbaugh, M.

1988-01-01

This paper reports a nuclear reaction analysis (NRA) for hydrogen technique used to analyze the hydrogen concentration near plasma enhanced chemical vapor deposition (PECVD) silicon nitride-polyimide interfaces at various nitride-deposition and polyimide-polymer-curing temperatures. The CF 4 + O 2 (8% O 2 ) plasma-etch-rate variation of PECVD silicon nitride films deposited on polyimide appeared to correlate well with the variation of hydrogen-depth profiles in the nitride films. The NRA data indicate that hydrogen-depth-profile fluctuation in the nitride films is due to hydrogen diffusion between the nitride-polyimide interfaces during deposition. Annealing treatment of polyimide films in a hydrogen atmosphere prior to the nitride film deposition tends to enhance the hydrogen-depth-profile uniformity in the nitride films, and thus substantially reduces or eliminates variation in the nitride plasma-etch rate

Novel synthesis of covalently linked silicon quantum dot–polystyrene hybrid materials: Silicon quantum dot–polystyrene polymers of tunable refractive index

Energy Technology Data Exchange (ETDEWEB)

Choi, Jin-Kyu; Dung, Mai Xuan; Jeong, Hyun-Dam, E-mail: hdjeong@chonnam.ac.kr

2014-11-14

We present a new material design concept, silicon quantum dot (Si QD) polymers, for which surface-functionalized Si QDs can be regarded as a large monomer in the polymers. As a prototypical example, vinyl-functionalized Si QDs, i.e., divinylbenzene-capped Si QDs (DVB-Si QDs) synthesized by adopting divinylbenzene (DVB) capping molecule to the hydride-terminated Si QD (H-Si QD) via Pt-catalyzed hydrosilylation was introduced and polymerized with a styrene monomer to yield Si QD–polystyrene (Si QD–PS) polymers. To demonstrate controllability of the content of Si QDs in the polymers as in conventional polymers, three Si QD content varied Si QD–PS polymers were systematically prepared, named as Si QD–PS-A, Si QD–PS-B, and Si QD–PS-C. It has been demonstrated that the content of the Si QDs in the Si QD–PS polymers was well controlled by the amount of the DVB-Si QD used, as found to be 3.8 wt% (Si QD–PS-A), 10.0 wt% (Si QD–PS-B), 20.0 wt% (Si QD–PS-A), and 37.4 wt% (DVB-Si QD), which was deduced from TGA results. Thin films of the Si QD–PS polymers and the freestanding DVB-Si QDs were successfully fabricated by a spin-coating method and it was found that the refractive index of the thin films dried at 40 °C was linearly increased as the content of the Si QD in the polymers was increased from 1.586 (0 wt%), to 1.590 (3.8 wt%), to 1.592 (10.0 wt%), to 1.592 (20.0 wt%), and to 1.614 (37.4 wt%). - Highlights: • A new material design concept, Si QD polymer, is presented. • Freestanding vinyl-functionalized Si QD was synthesized as a monomer for polymer. • Si QD–PS polymers were synthesized by polymerization of styrene with vinyl-Si QD. • Concentration of Si QD in the polymer was well controlled by amount of Si QD used. • Refractive index of polymer thin films linearly increased with concentration of Si QD.

Novel synthesis of covalently linked silicon quantum dot–polystyrene hybrid materials: Silicon quantum dot–polystyrene polymers of tunable refractive index

International Nuclear Information System (INIS)

Choi, Jin-Kyu; Dung, Mai Xuan; Jeong, Hyun-Dam

2014-01-01

We present a new material design concept, silicon quantum dot (Si QD) polymers, for which surface-functionalized Si QDs can be regarded as a large monomer in the polymers. As a prototypical example, vinyl-functionalized Si QDs, i.e., divinylbenzene-capped Si QDs (DVB-Si QDs) synthesized by adopting divinylbenzene (DVB) capping molecule to the hydride-terminated Si QD (H-Si QD) via Pt-catalyzed hydrosilylation was introduced and polymerized with a styrene monomer to yield Si QD–polystyrene (Si QD–PS) polymers. To demonstrate controllability of the content of Si QDs in the polymers as in conventional polymers, three Si QD content varied Si QD–PS polymers were systematically prepared, named as Si QD–PS-A, Si QD–PS-B, and Si QD–PS-C. It has been demonstrated that the content of the Si QDs in the Si QD–PS polymers was well controlled by the amount of the DVB-Si QD used, as found to be 3.8 wt% (Si QD–PS-A), 10.0 wt% (Si QD–PS-B), 20.0 wt% (Si QD–PS-A), and 37.4 wt% (DVB-Si QD), which was deduced from TGA results. Thin films of the Si QD–PS polymers and the freestanding DVB-Si QDs were successfully fabricated by a spin-coating method and it was found that the refractive index of the thin films dried at 40 °C was linearly increased as the content of the Si QD in the polymers was increased from 1.586 (0 wt%), to 1.590 (3.8 wt%), to 1.592 (10.0 wt%), to 1.592 (20.0 wt%), and to 1.614 (37.4 wt%). - Highlights: • A new material design concept, Si QD polymer, is presented. • Freestanding vinyl-functionalized Si QD was synthesized as a monomer for polymer. • Si QD–PS polymers were synthesized by polymerization of styrene with vinyl-Si QD. • Concentration of Si QD in the polymer was well controlled by amount of Si QD used. • Refractive index of polymer thin films linearly increased with concentration of Si QD

Nanoshaving and Nanografting of Water Soluble Polymers on Glass and Silicon Dioxide Surfaces with Applications to DNA Localization

Science.gov (United States)

Davis, Brian; Conley, Hiram; Ochoa, Rosie; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

2008-10-01

Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Here we present a scanning probe lithography technique that allows for patterning of aqueous polymers on glass or silicon dioxide surfaces. The surfaces were functionalized by covalently bonding a silane monolayer with a known surface charge to either a glass slide or a silicon wafer. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer, passivating the functionalized surface. An Atomic Force Microscope (AFM) probe was used to remove a portion of the polymer layer, exposing the functional silane layer underneath. Employing this method we made chemically active submicron regions. These regions were backfilled with a fluorescent polymer and Lambda-DNA. Chemical differentiation was verified through tapping mode AFM and optical fluorescent microscopy. Lines with a pitch as small as 20nm were observed with AFM height and phase mode data.

Release of low molecular weight silicones and platinum from silicone breast implants.

Science.gov (United States)

Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

1997-12-01

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was

Radiation stable, hybrid, chemical vapor infiltration/preceramic polymer joining of silicon carbide components

Energy Technology Data Exchange (ETDEWEB)

Khalifa, Hesham E., E-mail: hesham.khalifa@ga.com [General Atomics, 3550 General Atomics Ct., San Diego 92121, CA (United States); Koyanagi, Takaaki [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge 37831, TN (United States); Jacobsen, George M.; Deck, Christian P.; Back, Christina A. [General Atomics, 3550 General Atomics Ct., San Diego 92121, CA (United States)

2017-04-15

This paper reports on a nuclear-grade joining material for bonding of silicon carbide-based components. The joint material is fabricated via a hybrid preceramic polymer, chemical vapor infiltration process. The joint is comprised entirely of β-SiC and results in excellent mechanical and permeability performance. The joint strength, composition, and microstructure have been characterized before and after irradiation to 4.5 dpa at 730 °C in the High Flux Isotope Reactor. The hybrid preceramic polymer-chemical vapor infiltrated joint exhibited complete retention of shear strength and no evidence of microstructural evolution or damage was detected following irradiation.

The effect of Low Earth Orbit exposure on some experimental fluorine and silicon-containing polymers

Science.gov (United States)

Connell, John W.; Young, Philip R.; Kalil, Carol G.; Chang, Alice C.; Siochi, Emilie J.

1994-01-01

Several experimental fluorine and silicon-containing polymers in film form were exposed to low Earth orbit (LEO) on a Space Shuttle flight experiment (STS-46, Evaluation of Oxygen Interaction with Materials, EOIM-3). The environmental parameters of primary concern were atomic oxygen (AO) and ultraviolet (UV) radiation. The materials were exposed to 2.3 plus or minus 0.1 x 10(exp 20) oxygen atoms/sq cm and 30.6 UV sun hours during the flight. In some cases, the samples were exposed at ambient, 120 C and 200 C. The effects of exposure on these materials were assessed utilizing a variety of characterization techniques including optical, scanning electron (SEM) and scanning tunneling (STM) microscopy, UV-visible (UV-VIS) transmission, diffuse reflectance infrared (DR-FTIR), x-ray photoelectron (XPS) spectroscopy, and in a few cases, gel permeation chromatography (GPC). In addition, weight losses of the films, presumably due to AO erosion, were measured. The fluorine-containing polymers exhibited significant AO erosion and exposed films were diffuse or 'frosted' in appearance and consequently displayed dramatic reductions in optical transmission. The silicon-containing films exhibited minimum AO erosion and the optical transmission of exposed films was essentially unchanged. The silicon near the exposed surface in the films was converted to silicate/silicon oxide upon AO exposure which subsequently provided protection for the underlying material. The silicon-containing epoxies are potentially useful as AO resistant coatings and matrix resins as they are readily processed into carbon fiber reinforced composites and cured via electron radiation.

Electrochemical study of lithium insertion into carbon-rich polymer-derived silicon carbonitride ceramics

International Nuclear Information System (INIS)

Kaspar, Jan; Mera, Gabriela; Nowak, Andrzej P.; Graczyk-Zajac, Magdalena; Riedel, Ralf

2010-01-01

This paper presents the lithium insertion into carbon-rich polymer-derived silicon carbonitride (SiCN) ceramic synthesized by the thermal treatment of poly(diphenylsilylcarbodiimide) at three temperatures, namely 1100, 1300, and 1700 o C under 0.1 MPa Ar atmosphere. At lower synthesis temperatures, the material is X-ray amorphous, while at 1700 o C, the SiCN ceramic partially crystallizes. Anode materials prepared from these carbon-rich SiCN ceramics without any fillers and conducting additives were characterized using cyclic voltammetry and chronopotentiometric charging/discharging. We found that the studied silicon carbonitride ceramics demonstrate a promising electrochemical behavior during lithium insertion/extraction in terms of capacity and cycling stability. The sample synthesized at 1300 o C exhibits a reversible capacity of 392 mAh g -1 . Our study confirms that carbon-rich SiCN phases are electrochemically active materials in terms of Li inter- and deintercalation.

"Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

Science.gov (United States)

McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

2016-02-01

Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.

Carbon elimination from silicon kerf: Thermogravimetric analysis and mechanistic considerations.

Science.gov (United States)

Vazquez-Pufleau, Miguel; Chadha, Tandeep S; Yablonsky, Gregory; Biswas, Pratim

2017-01-18

40% of ultrapure silicon is lost as kerf during slicing to produce wafers. Kerf is currently not being recycled due to engineering challenges and costs associated with removing its abundant impurities. Carbon left behind from the lubricant remains as one of the most difficult contaminants to remove in kerf without significant silicon oxidation. The present work enables to better understand the mechanism of carbon elimination in kerf which can aid the design of better processes for kef recycling and low cost photovoltaics. In this paper, we studied the kinetics of carbon elimination from silicon kerf in two atmospheres: air and N 2, under a regime of no-diffusion-limitation. We report the apparent activation energy in both atmospheres using three methods: Kissinger, and two isoconversional approaches. In both atmospheres, a bimodal apparent activation energy is observed, suggesting a two stage process. A reaction mechanism is proposed in which (a) C-C and C-O bond cleavage reactions occur in parallel with polymer formation; (b) at higher temperatures, this polymer fully degrades in air but leaves a tarry residue in N 2 that accounts for about 12% of the initial total carbon.

Improving the cycling stability of silicon nanowire anodes with conducting polymer coatings

KAUST Repository

Yao, Yan; Liu, Nian; McDowell, Matthew T.; Pasta, Mauro; Cui, Yi

2012-01-01

For silicon nanowires (Si NWs) to be used as a successful high capacity lithium-ion battery anode material, improvements in cycling stability are required. Here we show that a conductive polymer surface coating on the Si NWs improves cycling stability; coating with PEDOT causes the capacity retention after 100 charge-discharge cycles to increase from 30% to 80% over bare NWs. The improvement in cycling stability is attributed to the conductive coating maintaining the mechanical integrity of the cycled Si material, along with preserving electrical connections between NWs that would otherwise have become electrically isolated during volume changes. © 2012 The Royal Society of Chemistry.

Mesoporous silicon oxide films and their uses as templates in obtaining nanostructured conductive polymers

Science.gov (United States)

Salgado, R.; Arteaga, G. C.; Arias, J. M.

2018-04-01

Obtaining conductive polymers (CPs) for the manufacture of OLEDs, solar cells, electrochromic devices, sensors, etc., has been possible through the use of electrochemical techniques that allow obtaining films of controlled thickness with positive results in different applications. Current trends point towards the manufacture of nanomaterials, and therefore it is necessary to develop methods that allow obtaining CPs with nanostructured morphology. This is possible by using a porous template to allow the growth of the polymeric materials. However, prior and subsequent treatments are required to separate the material from the template so that it can be evaluated in the applications mentioned above. This is why mesoporous silicon oxide films (template) are essential for the synthesis of nanostructured polymers since both the template and the polymer are obtained on the electrode surface, and therefore it is not necessary to separate the material from the template. Thus, the material can be evaluated directly in the applications mentioned above. The dimensions of the resulting nanostructures will depend on the power, time and technique used for electropolymerization as well as the monomer and the surfactant of the mesoporous film.

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene polymer waveguide

International Nuclear Information System (INIS)

Chiu, J.-J.; Perng, Tsong P

2008-01-01

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene (BCB) waveguide were investigated. The silicon nanoparticles, of a size varying from 6 to 25 nm, were prepared by vapor condensation. The transmission modes and losses were examined by the prism coupler and cut-back methods. A He-Ne laser beam with a wavelength of 6328 A was used to measure the effective index and thickness of the waveguide. Laser light could be efficiently coupled into the BCB waveguide when the embedded Si nanoparticles were smaller than 6 nm. The film thickness and effective index of the Si-embedded BCB waveguide were measured to be 1.825 μm and 1.565, respectively. The optical transmission losses of the pure BCB and Si-embedded ridge waveguides measured by the cut-back method were 0.85 and 1.63 dB cm -1 , respectively. Although the optical loss was increased by the embedded Si, the disturbance of the output contour was quite small. This result demonstrates that the nanoparticle-embedded polymer waveguide may be used for optoelectronic integrated circuits

Structure and properties of nanocrystalline soft magnetic composite materials with silicon polymer matrix

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Nowosielski, R.; Konieczny, J.; PrzybyI, A.; WysIocki, J.

2005-01-01

The paper concerns investigation of nanocrystalline composites technology preparation. The composites in the form of rings with rectangular transverse section, and with polymer matrix and nanocrystalline metallic powders fulfillment were made, for obtaining good ferromagnetic properties. The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses strips in an as-quenched state. Generally for investigation, Co matrix alloys with the silicon polymer were used. Magnetic properties in the form of hysteresis loop by rings method were measured. Generally composite cores showed lower soft ferromagnetic properties than winded cores of nanocrystalline strips, but composite cores showed interesting mechanical properties. Furthermore, the structure of strips and powders on properties of composites were investigated

Monolithic amorphous silicon modules on continuous polymer substrate

Energy Technology Data Exchange (ETDEWEB)

Grimmer, D.P. (Iowa Thin Film Technologies, Inc., Ames, IA (United States))

1992-03-01

This report examines manufacturing monolithic amorphous silicon modules on a continuous polymer substrate. Module production costs can be reduced by increasing module performance, expanding production, and improving and modifying production processes. Material costs can be reduced by developing processes that use a 1-mil polyimide substrate and multilayers of low-cost material for the front encapsulant. Research to speed up a-Si and ZnO deposition rates is needed to improve throughputs. To keep throughput rates compatible with depositions, multibeam fiber optic delivery systems for laser scribing can be used. However, mechanical scribing systems promise even higher throughputs. Tandem cells and production experience can increase device efficiency and stability. Two alternative manufacturing processes are described: (1) wet etching and sheet handling and (2) wet etching and roll-to-roll fabrication.

Influence of Weak Base Addition to Hole-Collecting Buffer Layers in Polymer:Fullerene Solar Cells

Directory of Open Access Journals (Sweden)

Jooyeok Seo

2017-02-01

Full Text Available We report the effect of weak base addition to acidic polymer hole-collecting layers in normal-type polymer:fullerene solar cells. Varying amounts of the weak base aniline (AN were added to solutions of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS. The acidity of the aniline-added PEDOT:PSS solutions gradually decreased from pH = 1.74 (AN = 0 mol% to pH = 4.24 (AN = 1.8 mol %. The electrical conductivity of the PEDOT:PSS-AN films did not change much with the pH value, while the ratio of conductivity between out-of-plane and in-plane directions was dependent on the pH of solutions. The highest power conversion efficiency (PCE was obtained at pH = 2.52, even though all devices with the PEDOT:PSS-AN layers exhibited better PCE than those with the pristine PEDOT:PSS layers. Atomic force microscopy investigation revealed that the size of PEDOT:PSS domains became smaller as the pH increased. The stability test for 100 h illumination under one sun condition disclosed that the PCE decay was relatively slower for the devices with the PEDOT:PSS-AN layers than for those with pristine PEDOT:PSS layers.

High cation transport polymer electrolyte

Science.gov (United States)

Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL; Klingler, Robert J [Westmont, IL

2007-06-05

A solid state ion conducting electrolyte and a battery incorporating same. The electrolyte includes a polymer matrix with an alkali metal salt dissolved therein, the salt having an anion with a long or branched chain having not less than 5 carbon or silicon atoms therein. The polymer is preferably a polyether and the salt anion is preferably an alkyl or silyl moiety of from 5 to about 150 carbon/silicon atoms.

Experimental Study of Enhancing Oil Recovery with Weak Base Alkaline/Surfactant/Polymer

Directory of Open Access Journals (Sweden)

Dandan Yin

2017-01-01

Full Text Available Na2CO3 was used together with surfactant and polymer to form the Alkaline/Surfactant/Polymer (ASP flooding system. Interfacial tension (IFT and emulsification of Dagang oil and chemical solutions were studied in the paper. The experiment results show that the ASP system can form super-low interfacial tension with crude oil and emulsified phase. The stability of the emulsion is enhanced by the Na2CO3, surfactant, and the soap generated at oil/water contact. Six core flooding experiments are conducted in order to investigate the influence of Na2CO3 concentration on oil recovery. The results show the maximum oil recovery can be obtained with 0.3 wt% surfactant, 0.6 wt% Na2CO3, and 2000 mg/L polymer. In a heterogeneous reservoir, the ASP flooding could not enhance the oil recovery by reducing IFT until it reaches the critical viscosity, which indicates expanding the sweep volume is the premise for reducing IFT to enhance oil recovery. Reducing or removing the alkali from ASP system to achieve high viscosity will reduce oil recovery because of the declination of oil displacement efficiency. Weak base ASP alkali can ensure that the whole system with sufficient viscosity can start the medium and low permeability layers and enhance oil recovery even if the IFT only reaches 10−2 mN/m.

Formation of nanosize poly(p-phenylene vinylene) in porous silicon substrate

International Nuclear Information System (INIS)

Le Rendu, P.; Nguyen, T.P.; Cheah, K.; Joubert, P.

2003-01-01

We report the results of optical investigations in porous silicon (PS)/poly(p-phenylene vinylene) (PPV) systems obtained by filling the pores of silicon wafers with polymer. By scanning electron microscopy (SEM), IR, and Raman spectroscopy, we observed that the porous silicon layer was thoroughly filled by the polymer with no significant change in the structure of the materials. This suggests that there is no interaction between the components. On the other hand, the photoluminescence (PL) spectra of the devices investigated at different temperatures (from 11 to 290 K) showed that both materials are active at low temperatures. Porous silicon has a band located at 398 nm while PPV has two bands at 528 and 570 nm. As the temperature increases, the PL intensity of porous silicon decreases and that PPV is blue shifted. A new band emerging at 473 nm may indicate an energy transfer from the porous silicon to PPV, involving short segments of the polymer. The band of PPV located at 515 nm becomes more dominant and indicates that the nanosize polymer films are formed in the pores of the silicon layer, in agreement with the results obtained by SEM, IR, and Raman analyses

Thiolated polymers: evaluation of their potential as dermoadhesive excipients.

Science.gov (United States)

Grießinger, Julia Anita; Bonengel, Sonja; Partenhauser, Alexandra; Ijaz, Muhammad; Bernkop-Schnürch, Andreas

2017-02-01

The objective of this study was to evaluate and compare four different thiolated polymers regarding their dermoadhesive potential. Therefore, three hydrophilic polymers (poly(acrylic acid), Carbopol 971 and carboxymethylcellulose) and a lipophilic polymer (silicone oil) were chosen to generate thiolated polymers followed by characterization. The total work of adhesion (TWA) and the maximum detachment force (MDF) of formulations containing modified and unmodified polymers were investigated on skin obtained from pig ears using a tensile sandwich technique. The synthesis of thiolated polymers provided 564 µmol, 1079 µmol, 482 µmol and 217 µmol thiol groups per gram poly(acrylic acid), Carbopol 971, carboxymethylcellulose and silicone oil, respectively. Hydrogels containing poly(acrylic acid)-cysteine, Carbopol 971-cysteine, and carboxymethylcellulose-cysteamine exhibited a 6-fold, 25-fold and 9-fold prolonged adhesion on porcine skin than the hydrogel formulations prepared from the corresponding unmodified polymers, respectively. Furthermore, thiolation of silicone oil with thioglycolic acid led to a 5-fold improvement in adhesion compared to the unmodified silicone oil. A comparison between the four thiolated polymer formulations showed a clear correlation between the amount of coupled thiol groups and the TWA. According to these results thiomers might also be useful excipients to provide a prolonged dermal resistance time of various formulations.

Silicon nanowire hybrid photovoltaics

KAUST Repository

Garnett, Erik C.

2010-06-01

Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

Silicon nanowire hybrid photovoltaics

KAUST Repository

Garnett, Erik C.; Peters, Craig; Brongersma, Mark; Cui, Yi; McGehee, Mike

2010-01-01

Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces

Science.gov (United States)

Ochoa, Rosie; Davis, Brian; Conley, Hiram; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

2008-10-01

Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM.

Blue electroluminescence nanodevice prototype based on vertical ZnO nanowire/polymer film on silicon substrate

International Nuclear Information System (INIS)

He Ying; Wang Junan; Chen Xiaoban; Zhang Wenfei; Zeng Xuyu; Gu Qiuwen

2010-01-01

We present a polymer-complexing soft template technique to construct the ZnO-nanowire/polymer light emitting device prototype that exhibits blue electrically driven emission with a relatively low-threshold voltage at room temperature in ambient atmosphere, and the ZnO-nanowire-based LED's emission wavelength is easily tuned by controlling the applied-excitation voltage. The nearly vertically aligned ZnO-nanowires with polymer film were used as emissive layers in the devices. The method uses polymer as binder in the LED device and dispersion medium in the luminescence layer, which stabilizes the quasi-arrays of ZnO nanowires embedding in a thin polymer film on silicon substrate and passivates the surface of ZnO nanocrystals, to prevent the quenching of luminescence. Additionally, the measurements of electrical properties showed that ZnO-nanowire/polymer film could significantly improve the conductivity of the film, which could be attributed to an increase in both Hall mobility and carrier concentration. The results indicated that the novel technique is a low-cost process for ZnO-based UV or blue light emission and reduces the requirement for achieving robust p-doping of ZnO film. It suggests that such ZnO-nanowire/polymer-based LEDs will be suitable for the electro-optical application.

Bio-mineralisation on the composites of silicon-based polymer and nanodiamond particles by a species of Serratia Bacteria

International Nuclear Information System (INIS)

Sammon, R.; Mitev, D.; Pramatarova, L.; Hikov, T.; Radeva, E.; Presker, R.

2014-01-01

Serratia sp. NCIMB 40259 is a non-pathogenic Gram-negative bacterium that is able to produce hydroxyapatite by a mechanism involving enzymic cleavage of organic phosphates. Serratia bacteria can attach and form a biofilm on glass, plastics, ceramics and metals and the method can be used to form three dimensional porous scaffolds and for coating 3D structures with hydroxyapatite. The production of calcium phosphate is driven by an acid phosphatase enzyme located in the bacterial cell wall, on fimbriae and within the bacterial extracellular polymeric matrix. Calcium phosphate ceramic may be obtained by two methods: In the first, crystals of calcium phosphate are formed extracellularly within the pre-formed bacterial biofilm grown on the substrata. In the second method, planktonic bacteria catalyse the formation of CaP in suspension and on solid substrata placed in the same container. Composite thin layer of silicon-based polymer and detonated nanodiamond (DND) particles was used as substrate for the process of biomineralization by a species of Serratia. The plasma polymerization (PP) method was chosen to obtain composites of silicon-based polymer, in which DND particles were incorporated. Over the past decades carbon-based nanostructures have been the focus of intense research due to their unique chemical and physical properties. Recently it was shown that the incorporation of the DND particles in a polymer matrix (an organosilicon polymer) changes their physico-chemical properties. The composite films are homogeneous, chemically resistant, thermally and mechanically stable, thus allowing a large amount of biological components to be loaded onto their surface and to be used in tissue engineering, regenerative medicine, implants, stents, biosensors and other medical and biological devices. The aim of this study was to investigate the process of biomineralisation by Serratia bacteria on various composites of silicon-based polymer and detonated nanodiamond particles

Interpenetrated polymer networks based on commercial silicone elastomers and ionic networks with high dielectric permittivity and self-healing properties

DEFF Research Database (Denmark)

Ogliani, Elisa; Yu, Liyun; Skov, Anne Ladegaard

the applicability. One method used to avoid this limitation is to increase the dielectric permittivity of the material in order to improve the actuation response at a given field. Recently, interpenetrating polymer networks (IPNs) based on covalently cross-linked commercial silicone elastomers and ionic networks...... from amino- and carboxylic acid- functional silicones have been designed[2] (Figure 1). This novel system provides both the mechanical stability and the high breakdown strength given by the silicone part of the IPNs and the high permittivity and the softening effect of the ionic network. Thus......,1 Hz), and the commercial elastomers RT625 and LR3043/30 provide thebest viscoelastic properties to the systems, since they maintain low viscous losses upon addition of ionic network. The values ofthe breakdown strength in all cases remain higher than that of the reference pure PDMS network (ranging...

Structure-Property Relationships in Polymer Derived Amorphous/Nano-Crystalline Silicon Carbide for Nuclear Applications

International Nuclear Information System (INIS)

Zunjarrao, Suraj C.; Singh, Abhishek K.; Singh, Raman P.

2006-01-01

Silicon carbide (SiC) is a promising candidate for several applications in nuclear reactors owing to its high thermal conductivity, high melting temperature, good chemical stability, and resistance to swelling under heavy ion bombardment. However, fabricating SiC by traditional powder processing route generally requires very high temperatures for pressureless sintering. Polymer derived ceramic materials offer unique advantages such as ability to fabricate net shaped components, incorporate reinforcements and relatively low processing temperatures. Furthermore, for SiC based ceramics fabricated using polymer infiltration process (PIP), the microstructure can be tailored by controlling the processing parameters, to get an amorphous, nanocrystalline or crystalline SiC. In this work, fabrication of polymer derived amorphous and nano-grained SiC is presented and its application as an in-core material is explored. Monolithic SiC samples are fabricated by controlled pyrolysis of allyl-hydrido-poly-carbo-silane (AHPCS) under inert atmosphere. Chemical changes, phase transformations and microstructural changes occurring during the pyrolysis process are studied as a function of the processing temperature. Polymer cross-linking and polymer to ceramic conversion is studied using infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are performed to monitor the mass loss and phase change as a function of temperature. X-ray diffraction studies are done to study the intermediate phases and microstructural changes. Variation in density is carefully monitored as a function of processing temperature. Owing to shrinkage and gas evolution during pyrolysis, precursor derived ceramics are inherently porous and composite fabrication typically involves repeated cycles of polymer re-infiltration and pyrolysis. However, there is a limit to the densification that can be achieved by this method and porosity in the final materials presents

Anisotropic Thermal Behavior of Silicone Polymer, DC 745

Energy Technology Data Exchange (ETDEWEB)

Adams, Jillian Cathleen [Univ. of Oregon, Eugene, OR (United States). Dept. of Chemistry; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Torres, Joseph Angelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Volz, Heather Michelle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gallegos, Jennifer Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Yang, Dali [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-09-02

In material applications, it is important to understand how polymeric materials behave in the various environments they may encounter. One factor governing polymer behavior is processing history. Differences in fabrication will result in parts with varied or even unintended properties. In this work, the thermal expansion behavior of silicone DC 745 is studied. Thermomechanical analysis (TMA) is used to determine changes in sample dimension resulting from changes in temperature. This technique can measure thermal events such as the linear coefficient of thermal expansion (CTE), melting, glass transitions, cure shrinkage, and internal relaxations. Using a thermomechanical analyzer (Q400 TMA), it is determined that DC 745 expands anisotropically when heated. This means that the material has a different CTE depending upon which direction is being measured. In this study, TMA experiments were designed in order to confirm anisotropic thermal behavior in multiple DC 745 samples of various ages and lots. TMA parameters such as temperature ramp rate, preload force, and temperature range were optimized in order to ensure the most accurate and useful data. A better understanding of the thermal expansion of DC 745 will allow for more accurate modeling of systems using this material.

Porous silicon-cyclodextrin based polymer composites for drug delivery applications.

Science.gov (United States)

Hernandez-Montelongo, J; Naveas, N; Degoutin, S; Tabary, N; Chai, F; Spampinato, V; Ceccone, G; Rossi, F; Torres-Costa, V; Manso-Silvan, M; Martel, B

2014-09-22

One of the main applications of porous silicon (PSi) in biomedicine is drug release, either as a single material or as a part of a composite. PSi composites are attractive candidates for drug delivery systems because they can display new chemical and physical characteristics, which are not exhibited by the individual constituents alone. Since cyclodextrin-based polymers have been proven efficient materials for drug delivery, in this work β-cyclodextrin-citric acid in-situ polymerization was used to functionalize two kinds of PSi (nanoporous and macroporous). The synthesized composites were characterized by microscopy techniques (SEM and AFM), physicochemical methods (ATR-FTIR, XPS, water contact angle, TGA and TBO titration) and a preliminary biological assay was performed. Both systems were tested as drug delivery platforms with two different model drugs, namely, ciprofloxacin (an antibiotic) and prednisolone (an anti-inflammatory), in two different media: pure water and PBS solution. Results show that both kinds of PSi/β-cyclodextrin-citric acid polymer composites, nano- and macro-, provide enhanced release control for drug delivery applications than non-functionalized PSi samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

Science.gov (United States)

Pintado-Herrera, Marina G; Lara-Martín, Pablo A; González-Mazo, Eduardo; Allan, Ian J

2016-09-01

There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC. © 2016 SETAC.

High aspect ratio micro tool manufacturing for polymer replication using mu EDM of silicon, selective etching and electroforming

DEFF Research Database (Denmark)

Tosello, Guido; Bissacco, Giuliano; Tang, Peter Torben

2008-01-01

Mass fabrication of polymer micro components with high aspect ratio micro-structures requires high performance micro tools allowing the use of low cost replication processes such as micro injection moulding. In this regard an innovative process chain, based on a combination of micro electrical di...... discharge machining (mu EDM) of a silicon substrate, electroforming and selective etching was used for the manufacturing of a micro tool. The micro tool was employed for polymer replication by means of the injection moulding process....

Functionalization of alkyne-terminated thermally hydrocarbonized porous silicon nanoparticles with targeting peptides and antifouling polymers: effect on the human plasma protein adsorption.

Science.gov (United States)

Wang, Chang-Fang; Mäkilä, Ermei M; Bonduelle, Colin; Rytkönen, Jussi; Raula, Janne; Almeida, Sérgio; Närvänen, Ale; Salonen, Jarno J; Lecommandoux, Sebastien; Hirvonen, Jouni T; Santos, Hélder A

2015-01-28

Porous silicon (PSi) nanomaterials combine a high drug loading capacity and tunable surface chemistry with various surface modifications to meet the requirements for biomedical applications. In this work, alkyne-terminated thermally hydrocarbonized porous silicon (THCPSi) nanoparticles were fabricated and postmodified using five bioactive molecules (targeting peptides and antifouling polymers) via a single-step click chemistry to modulate the bioactivity of the THCPSi nanoparticles, such as enhancing the cellular uptake and reducing the plasma protein association. The size of the nanoparticles after modification was increased from 176 to 180-220 nm. Dextran 40 kDa modified THCPSi nanoparticles showed the highest stability in aqueous buffer. Both peptide- and polymer-functionalized THCPSi nanoparticles showed an extensive cellular uptake which was dependent on the functionalized moieties presented on the surface of the nanoparticles. The plasma protein adsorption study showed that the surface modification with different peptides or polymers induced different protein association profiles. Dextran 40 kDa functionalized THCPSi nanoparticles presented the least protein association. Overall, these results demonstrate that the "click" conjugation of the biomolecules onto the alkyne-terminated THCPSi nanoparticles is a versatile and simple approach to modulate the surface chemistry, which has high potential for biomedical applications.

Performance of a polymer coated silicon microarray for simultaneous detection of food allergen-specific IgE and IgG4.

Science.gov (United States)

Sievers, S; Cretich, M; Gagni, P; Ahrens, B; Grishina, G; Sampson, H A; Niggemann, B; Chiari, M; Beyer, K

2017-08-01

Microarray-based component-resolved diagnostics (CRD) has become an accepted tool to detect allergen-specific IgE sensitization towards hundreds of allergens in parallel from one drop of serum. Nevertheless, specificity and sensitivity as well as a simultaneous detection of allergen-specific IgG 4 , as a potential parameter for tolerance development, remain to be optimized. We applied the recently introduced silicon chip coated with a functional polymer named copoly(DMA-NAS-MAPS) to the simultaneous detection of food allergen-specific IgE and IgG 4 , and compared it with ImmunoCAP and ImmunoCAP ISAC. Inter- and intraslide variation, linearity of signal and working range, sensitivity and application of internal calibrations for IgE and IgG 4 were assessed. Native and recombinant allergenic proteins from hen's egg and cow's milk were spotted on silicon chips coated with copoly(DMA-NAS-MAPS) along with known concentrations for human IgE and IgG 4 . A serum pool and 105 patient samples were assessed quantitatively and semi-quantitatively with the ImmunoCAP and ImmunoCAP ISAC and correlated with IgE- and IgG 4 -specific fluorescence on silicon microarrays. Allergen-specific IgE and IgG 4 were detected in parallel using two fluorescent dyes with no crosstalk. Results from the ImmunoCAP correlated better with microarray fluorescence than with ImmunoCAP ISAC except for the allergen ovomucoid. The working range of the silicon microarray for total hen's egg-specific IgE was comparable to the range of 0.1 to >100 kU A /L of the ImmunoCAP system, whereas for total cow's milk, the silicon microarray was less sensitive. Detectable allergen-specific IgG 4 could be determined only for low concentrations, but still correlated positively with ImmunoCAP results. We confirmed the ability of the polymer coated silicon microarray to be comparably sensitive to the ImmunoCAP ISAC for various food allergens. This suggests that the copoly(DMA-NAS-MAPS) microarray is a low-cost, self

Minimizing scattering from antireflective surfaces replicated from low-aspect-ratio black silicon

DEFF Research Database (Denmark)

Christiansen, Alexander Bruun; Clausen, Jeppe; Mortensen, N. Asger

2012-01-01

The scattering properties of randomly structured antireflective black silicon polymer replica have been investigated. Using a two-step casting process, the structures can be replicated in Ormocomp on areas of up to 3 in. in diameter. Fourier analysis of scanning electron microscopy images...

Regenerable, innovative porous silicon-based polymer-derived ceramics for removal of methylene blue and rhodamine B from textile and environmental waters.

Science.gov (United States)

Bruzzoniti, Maria Concetta; Appendini, Marta; Onida, Barbara; Castiglioni, Michele; Del Bubba, Massimo; Vanzetti, Lia; Jana, Prasanta; Sorarù, Gian Domenico; Rivoira, Luca

2018-04-01

The presence of residual color in treated textile wastewater above the regulation limits is still a critical issue in many textile districts. Innovative, polymer-derived ceramics of the Si-C-O system were here synthesized in order to obtain porous nanocomposite materials where a free carbon phase is dispersed into a silicon carbide/silicon oxycarbide network. The sorbents were comprehensively characterized for the removal of two model water-soluble dyes (i.e., the cation methylene blue and the zwitterion rhodamine B). Adsorption is very rapid and controlled by intra-particle and/or film diffusion, depending on dye concentration. Among the nanocomposites studied, the SiOC aerogel (total capacity about 45 mg/g, is easily regenerated under mild treatment (250 °C, 2 h). Adsorption of dyes is not affected by the matrix composition: removals of 150 mg/L methylene blue from river water and simulated textile wastewater with high content of metal ions (2-50 mg/L) and chemical oxygen demand (800 mg/L) were higher than 92% and quantitative for a dye concentration of 1 mg/L.

Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

International Nuclear Information System (INIS)

Bloomfield, P.

1992-01-01

The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end

Asphaltenes-based polymer nano-composites

Science.gov (United States)

Bowen, III, Daniel E

2013-12-17

Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

Fabrication of a multifunctional nano-in-micro drug delivery platform by microfluidic templated encapsulation of porous silicon in polymer matrix.

Science.gov (United States)

Zhang, Hongbo; Liu, Dongfei; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Herranz-Blanco, Bárbara; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-07-09

A multifunctional nano-in-micro drug delivery platform is developed by conjugating the porous silicon nanoparticles with mucoadhesive polymers and subsequent encapsulation into a pH-responsive polymer using microfluidics. The multistage platform shows monodisperse size distribution and pH-responsive payload release, and the released nanoparticles are mucoadhesive. Moreover, this platform is capable of simultaneously loading and releasing multidrugs with distinct properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Aspect Ratio Sub-15 nm Silicon Trenches From Block Copolymer Templates

Science.gov (United States)

Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Olynick, Deirdre; Russell, Thomas; University of Massachusetts Amherst Collaboration; Oxford Instrument Collaboration; Lawrence Berkeley National Lab Collaboration

2013-03-01

High-aspect-ratio sub-15 nm silicon trenches are fabricated directly from plasma etching of a block copolymer (BCP) mask. Polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) 40k-b-18k was spin coated and solvent annealed to form cylindrical structures parallel to the silicon substrate. The BCP thin film was reconstructed by immersion in ethanol and then subjected to an oxygen and argon reactive ion etching to fabricate the polymer mask. A low temperature ion coupled plasma with sulfur hexafluoride and oxygen was used to pattern transfer block copolymer structure to silicon with high selectivity (8:1) and fidelity. The silicon pattern was characterized by scanning electron microscopy and grazing incidence x-ray scattering. We also demonstrated fabrication of silicon nano-holes using polystyrene-b-polyethylene oxide (PS-b-PEO) using same methodology described above for PS-b-P2VP. Finally, we show such silicon nano-strucutre serves as excellent nano-imprint master template to pattern various functional materials like poly 3-hexylthiophene (P3HT).

Rectangular-cladding silicon slot waveguide with improved nonlinear performance

Science.gov (United States)

Huang, Zengzhi; Huang, Qingzhong; Wang, Yi; Xia, Jinsong

2018-04-01

Silicon slot waveguides have great potential in hybrid silicon integration to realize nonlinear optical applications. We propose a rectangular-cladding hybrid silicon slot waveguide. Simulation result shows that, with a rectangular-cladding, the slot waveguide can be formed by narrower silicon strips, so the two-photon absorption (TPA) loss in silicon is decreased. When the cladding material is a nonlinear polymer, the calculated TPA figure of merit (FOMTPA) is 4.4, close to the value of bulk nonlinear polymer of 5.0. This value confirms the good nonlinear performance of rectangular-cladding silicon slot waveguides.

Smart Polymers with Special Wettability.

Science.gov (United States)

Chang, Baisong; Zhang, Bei; Sun, Taolei

2017-01-01

Surface wettability plays a key role in addressing issues ranging from basic life activities to our daily life, and thus being able to control it is an attractive goal. Learning from nature, both of its structure and function, brings us much inspiration in designing smart polymers to tackle this major challenge. Life functions particularly depend on biomolecular recognition-induced interfacial properties from the aqueous phase onto either "soft" cell and tissue or "hard" inorganic bone and tooth surfaces. The driving force is noncovalent weak interactions rather than strong covalent combinations. An overview is provided of the weak interactions that perform vital actions in mediating biological processes, which serve as a basis for elaborating multi-component polymers with special wettabilities. The role of smart polymers from molecular recognitions to macroscopic properties are highlighted. The rationale is that highly selective weak interactions are capable of creating a dynamic synergetic communication in the building components of polymers. Biomolecules could selectively induce conformational transitions of polymer chains, and then drive a switching of physicochemical properties, e.g., roughness, stiffness and compositions, which are an integrated embodiment of macroscopic surface wettabilities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compounds from silicones alter enzyme activity in curing barnacle glue and model enzymes.

Science.gov (United States)

Rittschof, Daniel; Orihuela, Beatriz; Harder, Tilmann; Stafslien, Shane; Chisholm, Bret; Dickinson, Gary H

2011-02-17

Attachment strength of fouling organisms on silicone coatings is low. We hypothesized that low attachment strength on silicones is, in part, due to the interaction of surface available components with natural glues. Components could alter curing of glues through bulk changes or specifically through altered enzyme activity. GC-MS analysis of silicone coatings showed surface-available siloxanes when the coatings were gently rubbed with a cotton swab for 15 seconds or given a 30 second rinse with methanol. Mixtures of compounds were found on 2 commercial and 8 model silicone coatings. The hypothesis that silicone components alter glue curing enzymes was tested with curing barnacle glue and with commercial enzymes. In our model, barnacle glue curing involves trypsin-like serine protease(s), which activate enzymes and structural proteins, and a transglutaminase which cross-links glue proteins. Transglutaminase activity was significantly altered upon exposure of curing glue from individual barnacles to silicone eluates. Activity of purified trypsin and, to a greater extent, transglutaminase was significantly altered by relevant concentrations of silicone polymer constituents. Surface-associated silicone compounds can disrupt glue curing and alter enzyme properties. Altered curing of natural glues has potential in fouling management.

Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

Science.gov (United States)

Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

2017-10-25

Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

Coupling of microphase separation and dewetting in weakly segregated diblock co-polymer ultrathin films.

Science.gov (United States)

Yan, Derong; Huang, Haiying; He, Tianbai; Zhang, Fajun

2011-10-04

We have studied the coupling behavior of microphase separation and autophobic dewetting in weakly segregated poly(ε-caprolactone)-block-poly(L-lactide) (PCL-b-PLLA) diblock co-polymer ultrathin films on carbon-coated mica substrates. At temperatures higher than the melting point of the PLLA block, the co-polymer forms a lamellar structure in bulk with a long period of L ∼ 20 nm, as determined using small-angle X-ray scattering. The relaxation procedure of ultrathin films with an initial film thickness of h = 10 nm during annealing has been followed by atomic force microscopy (AFM). In the experimental temperature range (100-140 °C), the co-polymer dewets to an ultrathin film of itself at about 5 nm because of the strong attraction of both blocks with the substrate. Moreover, the dewetting velocity increases with decreasing annealing temperatures. This novel dewetting kinetics can be explained by a competition effect of the composition fluctuation driven by the microphase separation with the dominated dewetting process during the early stage of the annealing process. While dewetting dominates the relaxation procedure and leads to the rupture of the ultrathin films, the composition fluctuation induced by the microphase separation attempts to stabilize them because of the matching of h to the long period (h ∼ 1/2L). The temperature dependence of these two processes leads to this novel relaxation kinetics of co-polymer thin films. © 2011 American Chemical Society

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

Science.gov (United States)

Chen, Zhuojie; She, Didi; Chen, Qinghua; Li, Yanmei; Wu, Wengang

2018-02-01

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

Performance Enhancement of Silicon Alloy-Based Anodes Using Thermally Treated Poly(amide imide) as a Polymer Binder for High Performance Lithium-Ion Batteries.

Science.gov (United States)

Yang, Hwi Soo; Kim, Sang-Hyung; Kannan, Aravindaraj G; Kim, Seon Kyung; Park, Cheolho; Kim, Dong-Won

2016-04-05

The development of silicon-based anodes with high capacity and good cycling stability for next-generation lithium-ion batteries is a very challenging task due to the large volume changes in the electrodes during repeated cycling, which results in capacity fading. In this work, we synthesized silicon alloy as an active anode material, which was composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. Poly(amide imide)s, (PAI)s, with different thermal treatments were used as polymer binders in the silicon alloy-based electrodes. A systematic study demonstrated that the thermal treatment of the silicon alloy electrodes at high temperature made the electrodes mechanically strong and remarkably enhanced the cycling stability compared to electrodes without thermal treatment. The silicon alloy electrode thermally treated at 400 °C initially delivered a discharge capacity of 1084 mAh g(-1) with good capacity retention and high Coulombic efficiency. This superior cycling performance was attributed to the strong adhesion of the PAI binder resulting from enhanced secondary interactions, which maintained good electrical contacts between the active materials, electronic conductors, and current collector during cycling. These findings are supported by results from X-ray photoelectron spectroscopy, scanning electron microscopy, and a surface and interfacial cutting analysis system.

Solid polymer electrolyte from phosphorylated chitosan

Energy Technology Data Exchange (ETDEWEB)

Fauzi, Iqbal, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Groups, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24

Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component’s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it’s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10{sup −6} S/cm up to 6.01 × 10{sup −4} S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10{sup −3} S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.

Preservative loss from silicone tubing during filling processes.

Science.gov (United States)

Saller, Verena; Matilainen, Julia; Rothkopf, Christian; Serafin, Daniel; Bechtold-Peters, Karoline; Mahler, Hanns-Christian; Friess, Wolfgang

2017-03-01

Significant loss of preservative was observed during filling of drug products during filling line stops. This study evaluated the losses of three commonly used preservatives in protein drugs, i.e. benzyl alcohol, phenol, and m-cresol. Concentration losses during static incubation were quantified and interpreted with regard to the potential driving forces for the underlying sorption, diffusion, and desorption steps. Partitioning from the solution into the silicone polymer was identified as the most decisive parameter for the extent of preservative loss. Additionally, the influence of tubing inner diameter, starting concentration as well as silicone tubing type was evaluated. Theoretical calculations assuming equilibrium between solution and tubing inner surface and one-directional diffusion following Fick's first law were used to approximate experimental data. Since significant losses were found already after few minutes, adequate measures must be taken to avoid deviations during filling of preservative-containing protein solutions that may impact product quality or antimicrobial efficacy. As a possible alternative to the highly permeable silicone tubing, a specific make of fluoropolymer tubing was identified being suitable for peristaltic pumps and not showing any preservative losses. Copyright © 2016 Elsevier B.V. All rights reserved.

Shock wave emission from laser-induced cavitation bubbles in polymer solutions.

Science.gov (United States)

Brujan, Emil-Alexandru

2008-09-01

The role of extensional viscosity on the acoustic emission from laser-induced cavitation bubbles in polymer solutions and near a rigid boundary is investigated by acoustic measurements. The polymer solutions consist of a 0.5% polyacrylamide (PAM) aqueous solution with a strong elastic component and a 0.5% carboxymethylcellulose (CMC) aqueous solution with a weak elastic component. A reduction of the maximum amplitude of the shock wave pressure and a prolongation of the oscillation period of the bubble were found in the elastic PAM solution. It might be caused by an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive. In both polymer solutions, however, the shock pressure decays proportionally to r(-1) with increasing distance r from the emission centre.

All-solid-state ion-selective silicone rubber membrane electrodes with a new conducting polymer

International Nuclear Information System (INIS)

Park, Eun Rang; Chung, Yeon Joon; Hwang, Sun Woo

2012-01-01

New conducting polymers containing heterocyclic rings with carbazole, ethylene dioxythiophene (EDOT) and benzobisthiazole were synthesized and the characterized by using organic spectroscopic methods. Potentiometric ion-selective membrane electrodes (ISMEs) have been extensively used for ion analysis in clinical, environmental, and industrial fields owing to their wide response range (4 to 7 orders of magnitude), no effect of sample turbidity, fast response time, and ease of miniaturization. Considerable attention has been given to alternative use of room-temperature vulcanizing (RTV)-type silicone rubber (SR) owing to its strong adhesion and high thermal durability. Unfortunately, the high membrane resistance of SR-based ion-selective membranes (ISMs) (2 to 3 higher orders of magnitude compared to those of poly(vinyl chloride)(PVC)-based ones) has significantly restricted their application. Herein, we demonstrate a new method to reduce the membrane resistance via addition of a new conducting polymer into the SR-based ISMs.

A novel and facile strategy for highly flame retardant polymer foam composite materials: Transforming silicone resin coating into silica self-extinguishing layer.

Science.gov (United States)

Wu, Qian; Zhang, Qian; Zhao, Li; Li, Shi-Neng; Wu, Lian-Bin; Jiang, Jian-Xiong; Tang, Long-Cheng

2017-08-15

In this study, a novel strategy was developed to fabricate highly flame retardant polymer foam composite materials coated by synthesized silicone resin (SiR) polymer via a facile dip-coating processing. Applying the SiR polymer coating, the mechanical property and thermal stability of SiR-coated polymer foam (PSiR) composites are greatly enhanced without significantly altering their structure and morphology. The minimum oxygen concentration to support the combustion of foam materials is greatly increased, i.e. from LOI 14.6% for pure foam to LOI 26-29% for the PSiR composites studied. Especially, adjusting pendant group to SiOSi group ratio (R/Si ratio) of SiRs produces highly flame retardant PSiR composites with low smoke toxicity. Cone calorimetry results demonstrate that 44-68% reduction in the peak heat release rate for the PSiR composites containing different R/Si ratios over pure foam is achieved by the presence of appropriate SiR coating. Digital and SEM images of post-burn chars indicate that the SiR polymer coating can be transformed into silica self-extinguishing porous layer as effective inorganic barrier effect, thus preserving the polymer foam structure from fire. Our results show that the SiR dip-coating technique is a promising strategy for producing flame retardant polymer foam composite materials with improved mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultralow Friction with Hydrophilic Polymer Brushes in Water as Segregated from Silicone Matrix

DEFF Research Database (Denmark)

Røn, Troels; Javakhishvili, Irakli; Hvilsted, Søren

2015-01-01

Lubrication is essential to minimize damage to underlying material and ensure low energy dissipation in biological and man-made mechanical sys- tems. Surface grafting of hydrophilic polymer brushes is a powerful means to render materials that are slippery in aqueous environments. However, presently......, as the hydrophilic polymer brushes are generated from an internal source of the material, excellent grafting stability and restoring capabilities are revealed even under harsh tribostress. The film can easily be applied to elastomers, metals, and ceramic substrates by spin- or drip-coating. Obtained sliding fric......- tion coefficients ( μ ) are 0.001–0.05 for soft contacts depending on substrate, load, counter surface, pH, and salinity. Between the two types of hydrophilic polymer chains, PAA shows far superior lubricity compared to PEG, which is rationalized by the larger reduction of total free energy...

Visual Sensor for Sterilization of Polymer Fixtures Using Embedded Mesoporous Silicon Photonic Crystals.

Science.gov (United States)

Kumeria, Tushar; Wang, Joanna; Chan, Nicole; Harris, Todd J; Sailor, Michael J

2018-01-26

A porous photonic crystal is integrated with a plastic medical fixture (IV connector hub) to provide a visual colorimetric sensor to indicate the presence or absence of alcohol used to sterilize the fixture. The photonic crystal is prepared in porous silicon (pSi) by electrochemical anodization of single crystal silicon, and the porosity and the stop band of the material is engineered such that the integrated device visibly changes color (green to red or blue to green) when infiltrated with alcohol. Two types of self-reporting devices are prepared and their performance compared: the first type involves heat-assisted fusion of a freestanding pSi photonic crystal to the connector end of a preformed polycarbonate hub, forming a composite where the unfilled portion of the pSi film acts as the sensor; the second involves generation of an all-polymer replica of the pSi photonic crystal by complete thermal infiltration of the pSi film and subsequent chemical dissolution of the pSi portion. Both types of sensors visibly change color when wetted with alcohol, and the color reverts to the original upon evaporation of the liquid. The sensor performance is verified using E. coli-infected samples.

Continuum Model for Decontamination of Chemical Warfare Agent from a Rubbery Polymer using the Maxwell-Stefan Formulation

Science.gov (United States)

Varady, Mark; Bringuier, Stefan; Pearl, Thomas; Stevenson, Shawn; Mantooth, Brent

Decontamination of polymers exposed to chemical warfare agents (CWA) often proceeds by application of a liquid solution. Absorption of some decontaminant components proceed concurrently with extraction of the CWA, resulting in multicomponent diffusion in the polymer. In this work, the Maxwell-Stefan equations were used with the Flory-Huggins model of species activity to mathematically describe the transport of two species within a polymer. This model was used to predict the extraction of the nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX) from a silicone elastomer into both water and methanol. Comparisons with experimental results show good agreement with minimal fitting of model parameters from pure component uptake data. Reaction of the extracted VX with sodium hydroxide in the liquid-phase was also modeled and used to predict the overall rate of destruction of VX. Although the reaction proceeds more slowly in the methanol-based solution compared to the aqueous solution, the extraction rate is faster due to increasing VX mobility as methanol absorbs into the silicone, resulting in an overall faster rate of VX destruction.

Surface modification of aluminum nitride by polysilazane and its polymer-derived amorphous silicon oxycarbide ceramic for the enhancement of thermal conductivity in silicone rubber composite

Science.gov (United States)

Chiu, Hsien Tang; Sukachonmakul, Tanapon; Kuo, Ming Tai; Wang, Yu Hsiang; Wattanakul, Karnthidaporn

2014-02-01

Polysilazane (PSZ) and its polymer-derived amorphous silicon oxycarbide (SiOC) ceramic were coated on aluminum nitride (AlN) by using a dip-coating method to allow moisture-crosslinking of PSZ on AlN, followed by heat treatment at 700 °C in air to convert PSZ into SiOC on AlN. The results from FTIR, XPS and SEM indicated that the surface of AlN was successfully coated by PSZ and SiOC film. It was found that the introduction of PSZ and SiOC film help improve in the interfacial adhesion between the modified AlN (PSZ/AlN and SiOC/AlN) and silicone rubber lead to the increase in the thermal conductivity of the composites since the thermal boundary resistance at the filler-matrix interface was decreased. However, the introduction of SiOC as an intermediate layer between AlN and silicone rubber could help increase the thermal energy transport at the filler-matrix interface rather than using PSZ. This result was due to the decrease in the surface roughness and thickness of SiOC film after heat treatment at 700 °C in air. Thus, in the present work, a SiOC ceramic coating could provide a new surface modification for the improvement of the interfacial adhesion between the thermally conductive filler and the matrix in which can enhance the thermal conductivity of the composites.

Water-soluble PEGylated silicon nanoparticles and their assembly into swellable nanoparticle aggregates

International Nuclear Information System (INIS)

Xu, Zejing; Li, Yejia; Zhang, Boyu; Purkait, Tapas; Alb, Alina; Mitchell, Brian S.; Grayson, Scott M.; Fink, Mark J.

2015-01-01

Water-soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water-stable chloroalkyl or alkynyl-terminated nanoparticles, respectively. Nanoparticles with the ω-chloroalkyl substituents were easily converted to ω-azidoalkyl groups through the reaction of the Si nanoparticles with sodium azide in DMF. The azido-terminated nanoparticles were then grafted with mono-alkynyl-PEG polymers using a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core–shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked Si nanoparticle clusters were synthesized via the CuAAC “click” reaction of functional Si NPs with α,ω-functional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle aggregates undergo a solvent-dependent change in volume (ethanol > dichloromethane > toluene) similar in behavior to hydrogel nanocomposites

Linear electro-optical behavior of hybrid nanocomposites based on silicon carbide nanocrystals and polymer matrices

Science.gov (United States)

Bouclé, J.; Kassiba, A.; Makowska-Janusik, M.; Herlin-Boime, N.; Reynaud, C.; Desert, A.; Emery, J.; Bulou, A.; Sanetra, J.; Pud, A. A.; Kodjikian, S.

2006-11-01

An electro-optical activity has been recently reported for hybrid nanocomposite thin films where inorganic silicon carbide nanocrystals (ncSiC) are incorporated into polymer matrices. The role of the interface SiC polymer is suggested as the origin of the observed second order nonlinear optical susceptibility in the hybrid materials based on poly-(methylmethacrylate) (PMMA) or poly-( N -vinylcarbazole) matrices. In this work, we report an analysis of the electro-optical response of this hybrid system as a function of the ncSiC content and surface state in order to precise the interface effect in the observed phenomenon. Two specific ncSiC samples with similar morphology and different surface states are incorporated in the PMMA matrix. The effective Pockels parameters of the corresponding hybrid nanocomposites have been estimated up to 7.59±0.74pm/V ( 1wt.% of ncSiC in the matrix). The interfacial region ncSiC polymer is found to play the main role in the observed effect. Particularly, the electronic defects on the ncSiC nanocrystal surface modify the interfacial electrical interactions between the two components. The results are interpreted and discussed on the basis of the strong influence of these active centers in the interfacial region at the nanoscale, which are found to monitor the local hyperpolarizabilities and the macroscopic nonlinear optical susceptibilities. This approach allows us to complete the description and understanding of the electro-optical response in the hybrid SiC /polymer systems.

Characterization of self-assembled monolayers (SAMs) on silicon substrate comparative with polymer substrate for Escherichia coli O157:H7 detection

International Nuclear Information System (INIS)

Moldovan, Carmen; Mihailescu, Carmen; Stan, Dana; Ruta, Lavinia; Iosub, Rodica; Gavrila, Raluca; Purica, Munizer; Vasilica, Schiopu

2009-01-01

This article presents the characterization of two substrates, silicon and polymer coated with gold, that are functionalized by mixed self-assembled monolayers (SAMs) in order to efficiently immobilize the anti-Escherichia coli O157:H7 polyclonal purified antibody. A biosurface functionalized by SAMs (self-assembled monolayers) technique has been developed. Immobilization of goat anti-E. coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayers (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold. The F(ab') 2 fragments of the antibodies have been used for eliminating nonspecific bindings between the Fc portions of antibodies and the Fc receptor on cells. The properties of the monolayers and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FTIR-ATR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and cyclic voltammetry (CV). In our study the gold-coated silicon substrates approach yielded the best results. These experimental results revealed the necessity to investigate each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions as well and also provide a solid basis for further studies aiming at elaborating sensitive and specific immunosensor or a microarray for the detection of E. coli O157:H7.

Characterization of self-assembled monolayers (SAMs) on silicon substrate comparative with polymer substrate for Escherichia coli O157:H7 detection

Energy Technology Data Exchange (ETDEWEB)

Moldovan, Carmen, E-mail: carmen.moldovan@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Mihailescu, Carmen, E-mail: carmen_mihail28@yahoo.com [University of Bucharest, 90-92 Sos Panduri, Bucharest (Romania); Stan, Dana, E-mail: dana_stan2005@yahoo.com [DDS Diagnostic, 1 Segovia Street, Bucharest (Romania); Ruta, Lavinia, E-mail: laviniacoco@yahoo.com [University of Bucharest, 90-92 Sos Panduri, Bucharest (Romania); Iosub, Rodica, E-mail: rodica.iosub@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Gavrila, Raluca, E-mail: raluca.gavrila@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Purica, Munizer, E-mail: munizer.purica@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Vasilica, Schiopu, E-mail: vasilica.schiopu@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania)

2009-08-30

This article presents the characterization of two substrates, silicon and polymer coated with gold, that are functionalized by mixed self-assembled monolayers (SAMs) in order to efficiently immobilize the anti-Escherichia coli O157:H7 polyclonal purified antibody. A biosurface functionalized by SAMs (self-assembled monolayers) technique has been developed. Immobilization of goat anti-E. coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayers (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold. The F(ab'){sub 2} fragments of the antibodies have been used for eliminating nonspecific bindings between the Fc portions of antibodies and the Fc receptor on cells. The properties of the monolayers and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FTIR-ATR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and cyclic voltammetry (CV). In our study the gold-coated silicon substrates approach yielded the best results. These experimental results revealed the necessity to investigate each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions as well and also provide a solid basis for further studies aiming at elaborating sensitive and specific immunosensor or a microarray for the detection of E. coli O157:H7.

3D morphology of photoactive layers of polymer solar cells

NARCIS (Netherlands)

Bavel, van S.S.

2009-01-01

Nanostructured polymer solar cells (PSCs) have emerged as a promising low-cost alternative to conventional silicon-based photovoltaic devices. Since PSCs can be fabricated by processing polymers, eventually together with other organic materials, from solution and depositing them onto different types

Initial Drug Dissolution from Amorphous Solid Dispersions Controlled by Polymer Dissolution and Drug-Polymer Interaction.

Science.gov (United States)

Chen, Yuejie; Wang, Shujing; Wang, Shan; Liu, Chengyu; Su, Ching; Hageman, Michael; Hussain, Munir; Haskell, Roy; Stefanski, Kevin; Qian, Feng

2016-10-01

To identify the key formulation factors controlling the initial drug and polymer dissolution rates from an amorphous solid dispersion (ASD). Ketoconazole (KTZ) ASDs using PVP, PVP-VA, HMPC, or HPMC-AS as polymeric matrix were prepared. For each drug-polymer system, two types of formulations with the same composition were prepared: 1. Spray dried dispersion (SDD) that is homogenous at molecular level, 2. Physical blend of SDD (80% drug loading) and pure polymer (SDD-PB) that is homogenous only at powder level. Flory-Huggins interaction parameters (χ) between KTZ and the four polymers were obtained by Flory-Huggins model fitting. Solution (13)C NMR and FT-IR were conducted to investigate the specific drug-polymer interaction in the solution and solid state, respectively. Intrinsic dissolution of both the drug and the polymer from ASDs were studied using a Higuchi style intrinsic dissolution apparatus. PXRD and confocal Raman microscopy were used to confirm the absence of drug crystallinity on the tablet surface before and after dissolution study. In solid state, KTZ is completely miscible with PVP, PVP-VA, or HPMC-AS, demonstrated by the negative χ values of -0.36, -0.46, -1.68, respectively; while is poorly miscible with HPMC shown by a positive χ value of 0.23. According to solution (13)C NMR and FT-IR studies, KTZ interacts with HPMC-AS strongly through H-bonding and dipole induced interaction; with PVPs and PVP-VA moderately through dipole-induced interactions; and with HPMC weakly without detectable attractive interaction. Furthermore, the "apparent" strength of drug-polymer interaction, measured by the extent of peak shift on NMR or FT-IR spectra, increases with the increasing number of interacting drug-polymer pairs. For ASDs with the presence of considerable drug-polymer interactions, such as KTZ/PVPs, KTZ/PVP-VA, or KTZ /HPMC-AS systems, drug released at the same rate as the polymer when intimate drug-polymer mixing was ensured (i.e., the SDD systems

Thermal resistor on the base of silicon and some polymer semiconductors

International Nuclear Information System (INIS)

Marupov, R.; Kasimov, Sh.T.; Achilov, T.Kh.; Karimov, Kh.S.; Akhmedov, Kh.M.

1995-01-01

The purpose of present work is investigation electrical properties ofthermal resistors which was made from second cast poly-crystal silicon,poly-carbazole, and compositions of poly-crystal silicon and poly-carbazole

Semiconductor Grade, Solar Silicon Purification Project. [photovoltaic solar energy conversion

Science.gov (United States)

Ingle, W. M.; Rosler, R. S.; Thompson, S. W.; Chaney, R. E.

1979-01-01

A low cost by-product, SiF4, is reacted with mg silicon to form SiF2 gas which is polymerized. The (SiF2)x polymer is heated forming volatile SixFy homologues which disproportionate on a silicon particle bed forming silicon and SiF4. The silicon analysis procedure relied heavily on mass spectroscopic and emission spectroscopic analysis. These analyses demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). However, electrical analysis via crystal growth reveal that the product contains compensated phosphorus and boron.

Conductive polymer and Si nanoparticles composite secondary particles and structured current collectors for high loading lithium ion negative electrode application

Science.gov (United States)

Liu, Gao

2017-07-11

Embodiments of the present invention disclose a composition of matter comprising a silicon (Si) nanoparticle coated with a conductive polymer. Another embodiment discloses a method for preparing a composition of matter comprising a plurality of silicon (Si) nanoparticles coated with a conductive polymer comprising providing Si nanoparticles, providing a conductive polymer, preparing a Si nanoparticle, conductive polymer, and solvent slurry, spraying the slurry into a liquid medium that is a non-solvent of the conductive polymer, and precipitating the silicon (Si) nanoparticles coated with the conductive polymer. Another embodiment discloses an anode comprising a current collector, and a composition of matter comprising a silicon (Si) nanoparticle coated with a conductive polymer.

Fiscal 1993 R and D project for industrial science and technology. Report on results of R and D on silicon-based high polymer material; 1993 nendo keisokei kobunshi zairyo no kenkyu kaihtsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-01

R and D was conducted on the silicon-based high polymer that are hoped for superior electronic/optical functions and heat/flame-resistant dynamical properties, for the purpose of establishing fundamental technologies such as molecular design, synthesis, material forming and evaluation method, with the fiscal 1993 results summarized. In the synthesis of electrically conductive silicon-based polymeric materials, a concept of indirect doping was presented, revealing that workability and electrically conductive properties were enhanced by additives. In the synthesis of new silicon-based polymeric materials capable of circuit plotting, studies were made on Si-Si bond forming reaction of alkoxydisilanes as well as on the correlation between polysilane skeleton structure and its property. In the synthesis of new silicon-based polymeric materials having for example a light-emitting function, evaluation was made on synthesis and light emitting property concerning the compound that controlled the silicon skeleton structure. In addition, R and D was conducted on the precision synthesis technology of compounds, on which manifestation of photoelectric conversion function was expected. Further, research was done on unsaturated and high coordination organosilicic compound, functionality of silicon-based high polymer, and synthesis/polymerization of silicon monomer. (NEDO)

Study of drug release and tablet characteristics of silicone adhesive matrix tablets.

Science.gov (United States)

Tolia, Gaurav; Li, S Kevin

2012-11-01

Matrix tablets of a model drug acetaminophen (APAP) were prepared using a highly compressible low glass transition temperature (T(g)) polymer silicone pressure sensitive adhesive (PSA) at various binary mixtures of silicone PSA/APAP ratios. Matrix tablets of a rigid high T(g) matrix forming polymer ethyl cellulose (EC) were the reference for comparison. Drug release study was carried out using USP Apparatus 1 (basket), and the relationship between the release kinetic parameters of APAP and polymer/APAP ratio was determined to estimate the excipient percolation threshold. The critical points attributed to both silicone PSA and EC tablet percolation thresholds were found to be between 2.5% and 5% w/w. For silicone PSA tablets, satisfactory mechanical properties were obtained above the polymer percolation threshold; no cracking or chipping of the tablet was observed above this threshold. Rigid EC APAP tablets showed low tensile strength and high friability. These results suggest that silicone PSA could eliminate issues related to drug compressibility in the formulation of directly compressed oral controlled release tablets of poorly compressible drug powder such as APAP. No routinely used excipients such as binders, granulating agents, glidants, or lubricants were required for making an acceptable tablet matrix of APAP using silicone PSA. Copyright © 2012 Elsevier B.V. All rights reserved.

About possible mechanisms of current transfer in the bio-polymer - semiconductor heterostructure

International Nuclear Information System (INIS)

Pavlov, A.A.; Dosmailov, M.A.; Karibaeva, M.K.; Kenshinbaev, N.K.; Kokanbaev, M.; Uristembekov, B.B.; Tynyshtykbaev, K.B.

2003-01-01

Earlier by the bio-polymer films deposition on silicon the bio-polymer - semiconductor heterostructures were created. The influence of silicon surface atoms on self-organization processes in these bio-molecules were studied. Particularly the silicon - bio-cholesterol aqueous solution and the silicon - bio-chlorophyll aqueous solution spectral photo-sensitivity were considered. In this case the of photo-response broadening in the spectral photo-sensitivity short-wave part of these systems have been observed. The similar broadening is explained by both the passivation of surface recombination centers by OH-groups and the anti-reflecting properties of aqueous solutions. Besides it is possible the additional charge carriers generation caused by quasi-inter-zone transfers in the bio-polymers depending on electron-conformation properties of macromolecules. In the paper the possible mechanisms of current transfer in the bio-polymer - semiconductor heterostructure are discussed

Athermal Photonic Devices and Circuits on a Silicon Platform

Science.gov (United States)

Raghunathan, Vivek

In recent years, silicon based optical interconnects has been pursued as an effective solution that can offer cost, energy, distance and bandwidth density improvements over copper. Monolithic integration of optics and electronics has been enabled by silicon photonic devices that can be fabricated using CMOS technology. However, high levels of device integration result in significant local and global temperature fluctuations that prove problematic for silicon based photonic devices. In particular, high temperature dependence of Si refractive index (thermo-optic (TO) coefficient) shifts the filter response of resonant devices that limit wavelength resolution in various applications. Active thermal compensation using heaters and thermo-electric coolers are the legacy solution for low density integration. However, the required electrical power, device foot print and number of input/output (I/O) lines limit the integration density. We present a passive approach to an athermal design that involves compensation of positive TO effects from a silicon core by negative TO effects of the polymer cladding. In addition, the design rule involves engineering the waveguide core geometry depending on the resonance wavelength under consideration to ensure desired amount of light in the polymer. We develop exact design requirements for a TO peak stability of 0 pm/K and present prototype performance of 0.5 pm/K. We explore the material design space through initiated chemical vapor deposition (iCVD) of 2 polymer cladding choices. We study the effect of cross-linking on the optical properties of a polymer and establish the superior performance of the co-polymer cladding compared to the homo-polymer. Integration of polymer clad devices in an electronic-photonic architecture requires the possibility of multi-layer stacking capability. We use a low temperature, high density plasma chemical vapor deposition of SiO2/SiN x to hermetically seal the athermal. Further, we employ visible light for

Polyacrylic acid polymer brushes as substrates for the incorporation of anthraquinone derivatives. Unprecedented application of decorated polymer brushes on organocatalysis

Science.gov (United States)

Ruiz-Muelle, Ana Belén; Contreras-Cáceres, Rafael; Oña-Burgos, Pascual; Rodríguez-Dieguez, Antonio; López-Romero, Juan Manuel; Fernández, Ignacio

2018-01-01

The synthesis of amino-terminated anthraquinone derivatives and their incorporation onto polymer brushes for the fabrication of silicon-based nanometric functional coatings are described for the first time. The general process involves the covalent grafting of anthraquinone 1 onto two different polymer-brushes by amidation reactions. They are composed by amino- and carboxy-terminated poly(acrylic acid) chains (PAA-NH2- and PAA-COOH, respectively) tethered by one end to an underlying silicon oxide (SiO2) substrate in a polymer brush configuration. A third substrate is fabricated by UV induced hydrosilylation reaction using undecenoic acid as adsorbate on hydrogen-terminated Si(111) surfaces. One- and two-dimensional nuclear magnetic resonance (NMR), FT-IR, MS and X-ray diffraction (XRD) were used to characterize anthraquinone 1. Ellipsometric and X-ray photoelectron spectroscopy (XPS) measurements demonstrated the presence of the polymer brushes on the silicon wafers, and atomic force microscopy (AFM) was used to study its surface morphology. The covalent linkage between anthraquinone and polymer brushes was proven by XPS and confocal fluorescence microscopy. The resulting surfaces were assayed in the heterogenous organocatalytic transformation of (1H)-indole into 3-benzyl indole with moderate yields but with high recyclability.

High-Throughput Fabrication of Nanocone Substrates through Polymer Injection Moulding For SERS Analysis in Microfluidic Systems

DEFF Research Database (Denmark)

Viehrig, Marlitt; Matteucci, Marco; Thilsted, Anil H.

analysis. Metal-capped silicon nanopillars, fabricated through a maskless ion etch, are state-of-the-art for on-chip SERS substrates. A dense cluster of high aspect ratio polymer nanocones was achieved by using high-throughput polymer injection moulding over a large area replicating a silicon nanopillar...... structure. Gold-capped polymer nanocones display similar SERS sensitivity as silicon nanopillars, while being easily integrable into a microfluidic chips....

Fluorescense Anisotropy Studies of Molecularly Imprinted Polymer Sensors

Energy Technology Data Exchange (ETDEWEB)

Chen, Yin-Chu; Wang, Zheming; Yan, Mingdi; Prahl, Scott A.

2005-08-03

Molecularly imprinted polymers (MIPs) are used as recognition elements in biochemical sensors. In a fluorescence-based MIP sensor system, it is difficult to distinguish the analyte fluorescence from the background fluorescence of the polymer itself. We studied steady-state fluorescence anisotropy of anthracene imprinted in a polymer (polyurethane) matrix. Vertically polarized excitation light was incident on MIP films coated on silicon wafers; vertically and horizontally polarized emission was measured. We compared the fluorescence anisotropy of MIPs with imprinted molecules, MIPs with the imprinted molecules extracted, MIPs with rebound molecules, and nonimprinted control polymers (without binding cavities). It is shown that differences in fluorescence anisotropy between the polymers and imprinted fluorescent molecules may provide a means to discriminate the fluorescence of analyte from that of the background polymer.

Microfluidic assembly of monodisperse multistage pH-responsive polymer/porous silicon composites for precisely controlled multi-drug delivery.

Science.gov (United States)

Liu, Dongfei; Zhang, Hongbo; Herranz-Blanco, Bárbara; Mäkilä, Ermei; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-05-28

We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Excimer laser decomposition of silicone

International Nuclear Information System (INIS)

Laude, L.D.; Cochrane, C.; Dicara, Cl.; Dupas-Bruzek, C.; Kolev, K.

2003-01-01

Excimer laser irradiation of silicone foils is shown in this work to induce decomposition, ablation and activation of such materials. Thin (100 μm) laminated silicone foils are irradiated at 248 nm as a function of impacting laser fluence and number of pulsed irradiations at 1 s intervals. Above a threshold fluence of 0.7 J/cm 2 , material starts decomposing. At higher fluences, this decomposition develops and gives rise to (i) swelling of the irradiated surface and then (ii) emission of matter (ablation) at a rate that is not proportioned to the number of pulses. Taking into consideration the polymer structure and the foil lamination process, these results help defining the phenomenology of silicone ablation. The polymer decomposition results in two parts: one which is organic and volatile, and another part which is inorganic and remains, forming an ever thickening screen to light penetration as the number of light pulses increases. A mathematical model is developed that accounts successfully for this physical screening effect

Neutron absorbing room temperature vulcanizable silicone rubber compositions

International Nuclear Information System (INIS)

Zoch, H.L.

1979-01-01

A neutron absorbing composition is described and consists of a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide. 20 claims

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

Directory of Open Access Journals (Sweden)

Gabriela Mera

2015-04-01

Full Text Available The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs. Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers.

Science.gov (United States)

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-04-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

Science.gov (United States)

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail. PMID:28347023

Removal of inclusions from silicon

Science.gov (United States)

Ciftja, Arjan; Engh, Thorvald Abel; Tangstad, Merete; Kvithyld, Anne; Øvrelid, Eivind Johannes

2009-11-01

The removal of inclusions from molten silicon is necessary to satisfy the purity requirements for solar grade silicon. This paper summarizes two methods that are investigated: (i) settling of the inclusions followed by subsequent directional solidification and (infiltration by ceramic foam filters. Settling of inclusions followed by directional solidification is of industrial importance for production of low-cost solar grade silicon. Filtration is reported as the most efficient method for removal of inclusions from the top-cut silicon scrap.

Novel fabrication of silicon carbide based ceramics for nuclear applications

Science.gov (United States)

Singh, Abhishek Kumar

Advances in nuclear reactor technology and the use of gas-cooled fast reactors require the development of new materials that can operate at the higher temperatures expected in these systems. These materials include refractory alloys based on Nb, Zr, Ta, Mo, W, and Re; ceramics and composites such as SiC--SiCf; carbon--carbon composites; and advanced coatings. Besides the ability to handle higher expected temperatures, effective heat transfer between reactor components is necessary for improved efficiency. Improving thermal conductivity of the fuel can lower the center-line temperature and, thereby, enhance power production capabilities and reduce the risk of premature fuel pellet failure. Crystalline silicon carbide has superior characteristics as a structural material from the viewpoint of its thermal and mechanical properties, thermal shock resistance, chemical stability, and low radioactivation. Therefore, there have been many efforts to develop SiC based composites in various forms for use in advanced energy systems. In recent years, with the development of high yield preceramic precursors, the polymer infiltration and pyrolysis (PIP) method has aroused interest for the fabrication of ceramic based materials, for various applications ranging from disc brakes to nuclear reactor fuels. The pyrolysis of preceramic polymers allow new types of ceramic materials to be processed at relatively low temperatures. The raw materials are element-organic polymers whose composition and architecture can be tailored and varied. The primary focus of this study is to use a pyrolysis based process to fabricate a host of novel silicon carbide-metal carbide or oxide composites, and to synthesize new materials based on mixed-metal silicocarbides that cannot be processed using conventional techniques. Allylhydridopolycarbosilane (AHPCS), which is an organometal polymer, was used as the precursor for silicon carbide. Inert gas pyrolysis of AHPCS produces near-stoichiometric amorphous

Molecular and supramolecular orientation in conducting polymers

International Nuclear Information System (INIS)

Aldissi, M.

1987-01-01

Intrinsic anisotropy in electrical and optical properties of conducting polymers constitutes a unique aspect that derives π-electron delocalization along the polymer backbone and from the weak inter-chain interaction. To acquire such an intrinsic property, conducting polymers have to be oriented macroscopically and microscopically (at the chain level). A review of the various techniques, including stretch-alignment of the polymer and of precursor polymers, polymerization in ordered media, i.e., in a liquid crystal solvent, and synthesis of liquid crystalline conducting polymers will be given. 29 refs

Nanocomposited coatings produced by laser-assisted process to prevent silicone hydogels from protein fouling and bacterial contamination

International Nuclear Information System (INIS)

Huang, Guobang; Chen, Yi; Zhang, Jin

2016-01-01

Graphical abstract: Nanocomposited-coating was deposited on silicone hydrogel by using the matrix-assisted pulsed laser evaporation (MAPLE) process. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel, and can inhibit the bacterial growth efficiently. - Highlights: • We developed a nanocomposited coating to prevent silicone hydrogel from biofouling. • Matrix-assisted pulsed laser evaporation can deposit inorganic–organic nanomaterials. • The designed nanocomposited coating reduces protein absorption by over 50%. • The designed nanocomposited coating shows significant antimicrobial efficiency. - Abstract: Zinc oxide (ZnO) nanoparticles incorporating with polyethylene glycol (PEG) were deposited together on the surface of silicone hydrogel through matrix-assisted pulsed laser evaporation (MAPLE). In this process, frozen nanocomposites (ZnO–PEG) in isopropanol were irradiated under a pulsed Nd:YAG laser at 532 nm for 1 h. Our results indicate that the MAPLE process is able to maintain the chemical backbone of polymer and prevent the nanocomposite coating from contamination. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel. The cytotoxicity study shows that the ZnO–PEG nanocomposites deposited on silicone hydrogels do not impose the toxic effect on mouse NIH/3T3 cells. In addition, MAPLE-deposited ZnO–PEG nanocomposites can inhibit the bacterial growth significantly.

Characterization of the silicon/hydrofluoric acid interface: electrochemical processes under weak potential disturbance

International Nuclear Information System (INIS)

Bertagna, Valerie

1996-01-01

Within the frame of the increase of the density of integrated circuits, of simplification of cleaning processes and of improvement of control of surface reactions (for a better control of the elimination of defects and contamination risks), this research thesis first gives a large overview of previous works in the fields of silicon electrochemistry in hydrofluoric environment, of silicon chemical condition after treatment by a diluted hydrofluoric acid, of metallic contamination of silicon during cleaning with a diluted hydrofluoric acid, and of theoretical models of interpretation. Then, the author reports the development of a new electrochemical cell, and the detailed study of mono-crystalline silicon in a diluted hydrofluoric environment (electrochemical investigation, modelling of charge transfer at the interface, studies by atomic force microscopy, contamination of silicon by copper)

Polymer waveguides for electro-optical integration in data centers and high-performance computers.

Science.gov (United States)

Dangel, Roger; Hofrichter, Jens; Horst, Folkert; Jubin, Daniel; La Porta, Antonio; Meier, Norbert; Soganci, Ibrahim Murat; Weiss, Jonas; Offrein, Bert Jan

2015-02-23

To satisfy the intra- and inter-system bandwidth requirements of future data centers and high-performance computers, low-cost low-power high-throughput optical interconnects will become a key enabling technology. To tightly integrate optics with the computing hardware, particularly in the context of CMOS-compatible silicon photonics, optical printed circuit boards using polymer waveguides are considered as a formidable platform. IBM Research has already demonstrated the essential silicon photonics and interconnection building blocks. A remaining challenge is electro-optical packaging, i.e., the connection of the silicon photonics chips with the system. In this paper, we present a new single-mode polymer waveguide technology and a scalable method for building the optical interface between silicon photonics chips and single-mode polymer waveguides.

Field assisted photoemission by silicon photocathodes

International Nuclear Information System (INIS)

Aboubacar, A.; Dupont, M.; El Manouni, A.; Querrou, M.; Says, L.P.

1991-01-01

Silicon photocathodes with arrays of tips have been prepared using microlithographic techniques. Current emission due to field effect has been measured in the case of heavy and weakly doped boron Silicon. An Argon continuous laser has been used to produce photocurrent. An instantaneous current (600 μA) with a moderate laser power (83 mW), has been produced on weakly doped photocathodes. This current corresponds to an average quantum yield (purely photoelectric) of about 1.7%, and a local current density in the range of a few 10 6 A m -2

Hybrid Silicon Nanocone–Polymer Solar Cells

KAUST Repository

Jeong, Sangmoo

2012-06-13

Recently, hybrid Si/organic solar cells have been studied for low-cost Si photovoltaic devices because the Schottky junction between the Si and organic material can be formed by solution processes at a low temperature. In this study, we demonstrate a hybrid solar cell composed of Si nanocones and conductive polymer. The optimal nanocone structure with an aspect ratio (height/diameter of a nanocone) less than two allowed for conformal polymer surface coverage via spin-coating while also providing both excellent antireflection and light trapping properties. The uniform heterojunction over the nanocones with enhanced light absorption resulted in a power conversion efficiency above 11%. Based on our simulation study, the optimal nanocone structures for a 10 μm thick Si solar cell can achieve a short-circuit current density, up to 39.1 mA/cm 2, which is very close to the theoretical limit. With very thin material and inexpensive processing, hybrid Si nanocone/polymer solar cells are promising as an economically viable alternative energy solution. © 2012 American Chemical Society.

Hybrid Silicon Nanocone–Polymer Solar Cells

KAUST Repository

Jeong, Sangmoo; Garnett, Erik C.; Wang, Shuang; Yu, Zongfu; Fan, Shanhui; Brongersma, Mark L.; McGehee, Michael D.; Cui, Yi

2012-01-01

Recently, hybrid Si/organic solar cells have been studied for low-cost Si photovoltaic devices because the Schottky junction between the Si and organic material can be formed by solution processes at a low temperature. In this study, we demonstrate a hybrid solar cell composed of Si nanocones and conductive polymer. The optimal nanocone structure with an aspect ratio (height/diameter of a nanocone) less than two allowed for conformal polymer surface coverage via spin-coating while also providing both excellent antireflection and light trapping properties. The uniform heterojunction over the nanocones with enhanced light absorption resulted in a power conversion efficiency above 11%. Based on our simulation study, the optimal nanocone structures for a 10 μm thick Si solar cell can achieve a short-circuit current density, up to 39.1 mA/cm 2, which is very close to the theoretical limit. With very thin material and inexpensive processing, hybrid Si nanocone/polymer solar cells are promising as an economically viable alternative energy solution. © 2012 American Chemical Society.

Radiation effects of ion beams on polymers

International Nuclear Information System (INIS)

Tagawa, Seiichi

1993-01-01

Recent progress in the radiation effects of ion beams on polymers are reviewed briefly. Our recent work on the radiation effects of ion beams on polystyrene thin films on silicon wafers and time resolved emission studies on polymers are described. (orig.)

Polymer dynamics from synthetic polymers to proteins

Indian Academy of Sciences (India)

Keywords. Polymer dynamics; reptation; domain dynamics biomolecules. Abstract. Starting from the standard model of polymer motion - the Rouse model - we briefly present some key experimental results on the mesoscopic dynamics of polymer systems. We touch the role of topological confinement as expressed in the ...

Nanofluidics : Silicon for the perfect membrane

NARCIS (Netherlands)

van den Berg, Albert; Wessling, Matthias

2007-01-01

Newly developed ultrathin silicon membranes can filter and separate molecules much more effectively than conventional polymer membranes. Many applications, of economic and medical significance, stand to benefit.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

Science.gov (United States)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Polymer Masks for nanostructuring of graphene

DEFF Research Database (Denmark)

Shvets, Violetta

This PhD project is a part of Center for Nanostructured Graphene (CNG) activities. The aim of the project is to develop a new lithography method for creation of highly ordered nanostructures with as small as possible feature and period sizes. The method should be applicable for graphene nanostruc...... demonstrated the opening of what could be interpreted as a band gap....... polymer masks is developed. Mask fabrication is realized by microtoming of 30-60 nm thin sections from pre-aligned polymer monoliths with different morphologies. The resulting polymer masks are then transferred to both silicon and graphene substrates. Hexagonally packed hole patterns with 10 nm hole...

Facile Synthesis of Porous Silicon Nanofibers by Magnesium Reduction for Application in Lithium Ion Batteries.

Science.gov (United States)

Cho, Daehwan; Kim, Moonkyoung; Hwang, Jeonghyun; Park, Jay Hoon; Joo, Yong Lak; Jeong, Youngjin

2015-12-01

We report a facile fabrication of porous silicon nanofibers by a simple three-stage procedure. Polymer/silicon precursor composite nanofibers are first fabricated by electrospinning, a water-based spinning dope, which undergoes subsequent heat treatment and then reduction using magnesium to be converted into porous silicon nanofibers. The porous silicon nanofibers are coated with a graphene by using a plasma-enhanced chemical vapor deposition for use as an anode material of lithium ion batteries. The porous silicon nanofibers can be mass-produced by a simple and solvent-free method, which uses an environmental-friendly polymer solution. The graphene-coated silicon nanofibers show an improved cycling performance of a capacity retention than the pure silicon nanofibers due to the suppression of the volume change and the increase of electric conductivity by the graphene.

Cementation of nuclear graphite using geo-polymers

International Nuclear Information System (INIS)

Girke, N.A.; Steinmetz, H.J.; Bukaemsky, A.; Bosbach, D.; Hermann, E.; Griebel, I.

2012-01-01

Geo-polymers are solid aluminosilicate materials usually formed by alkali hydroxide or alkali silicate activation of solid precursors such as coal fly ash, calcined clay and/or metallurgical slag. Today the primary application of geo-polymer technology is in the development of alternatives to Portland-based cements. Variations in the ratio of aluminium to silicon, and alkali to silicon or addition of structure support, produce geo-polymers with different physical and mechanical properties. These materials have an amorphous three-dimensional structure that gives geo-polymers certain properties, such as fire and acid resistance, low leach rate, which make them an ideal substitute for ordinary Portland cement (OPC) in a wide range of applications especially in conditioning and storage of radioactive waste. Therefore investigations have been initiated about how and to which amount graphite as a hydrophobic material can be mixed with cement or concrete to form stable waste products and which concretes fulfill the specifications at best. As result geo-polymers have been identified as a promising matrix for graphite containing nuclear wastes. With geo-polymers both favorable properties in the cementation process and a high long time structural stability of the products can be achieved. (authors)

Scattering characteristics from porous silicon

Directory of Open Access Journals (Sweden)

R. Sabet-Dariani

2000-12-01

Full Text Available   Porous silicon (PS layers come into existance as a result of electrochemical anodization on silicon. Although a great deal of research has been done on the formation and optical properties of this material, the exact mechanism involved is not well-understood yet.   In this article, first, the optical properties of silicon and porous silicon are described. Then, previous research and the proposed models about reflection from PS and the origin of its photoluminescence are reveiwed. The reflecting and scattering, absorption and transmission of light from this material, are then investigated. These experiments include,different methods of PS sample preparation their photoluminescence, reflecting and scattering of light determining different characteristics with respect to Si bulk.

Investigations of surface characterization of silicone rubber due to ...

Indian Academy of Sciences (India)

Unknown

†Department of Polymer Technology, Crescent Engineering College, Chennai 600 048, India. Abstract. In the present work, tracking ... Silicone rubber; surface degradation; tracking; WAXD; TG–DTA. 1. Introduction. Power transmission at ... mena in polymer insulators under d.c. voltages. Hence the tracking phenomena ...

High strength films from oriented, hydrogen-bonded "graphamid" 2D polymer molecular ensembles.

Science.gov (United States)

Sandoz-Rosado, Emil; Beaudet, Todd D; Andzelm, Jan W; Wetzel, Eric D

2018-02-27

The linear polymer poly(p-phenylene terephthalamide), better known by its tradename Kevlar, is an icon of modern materials science due to its remarkable strength, stiffness, and environmental resistance. Here, we propose a new two-dimensional (2D) polymer, "graphamid", that closely resembles Kevlar in chemical structure, but is mechanically advantaged by virtue of its 2D structure. Using atomistic calculations, we show that graphamid comprises covalently-bonded sheets bridged by a high population of strong intermolecular hydrogen bonds. Molecular and micromechanical calculations predict that these strong intermolecular interactions allow stiff, high strength (6-8 GPa), and tough films from ensembles of finite graphamid molecules. In contrast, traditional 2D materials like graphene have weak intermolecular interactions, leading to ensembles of low strength (0.1-0.5 GPa) and brittle fracture behavior. These results suggest that hydrogen-bonded 2D polymers like graphamid would be transformative in enabling scalable, lightweight, high performance polymer films of unprecedented mechanical performance.

Radiation application for synthesis of advanced materials and the related research on polymers

International Nuclear Information System (INIS)

Seguchi, T.

1996-01-01

The irradiation effects of polymers was studied in the wide temperature range from very low temperature to high temperature under vacuum or oxygen free atmosphere.The chemical reactions for polymers showed a rather large difference depending on irradiation temperature in quality and/or quantity. The dependence is though to be the difference in molecular motion of polymers during irradiation. The clear difference on irradiation temperature was observed for polytetrafluoroethylene(PTFE) and polystyrene(PS). For other polymers, the irradiation temperature effects are observed, which may be expanding to develop new products. The newly developed technology in radiation application is the curing of polymer fiber as ceramic fiber precursor. The silicon carbide(SiC) fiber is synthesized from silicon containing polymer of polycarbosilane(PCS) fiber by the pyrolysis at high temperature of 1200 deg or more. As the melting temperature of PCS is about 230 deg, the fiber must be cured to not melt down during the pyrolysis. The purpose of this work was the radiation crosslinking of PCS fiber without oxygen contamination. The basic research was carried out using gamma-rays irradiation under vacuum, where the fundamental data were obtained such as the yield of active sites and the reactivity with oxygen and the decomposed gases. The SiC fiber obtained from the radiation cured PCS fiber has a high tensile strength of 3GPa and high heat-resistance up to 1700 deg. The heat resistance of SiC fiber obtained from ordinary processing is about 1200 deg. This technology was transferred to a company and the product is supplied to the market. The silicon nitride(Si 3 N 4 ) fibre was also synthesized from radiation cured PCS fiber by the pyrolysis in ammonia gas atmosphere

Silicon-containing polyoxadiazoles-synthesis and perspectives.

Science.gov (United States)

Bruma, Maria; Köpnick, Thomas

2005-11-30

A review is presented on those polymers which contain diphenylsilylene units and 1,3,4-oxadiazole rings either in the main chain or in the pendent groups. The synthesis of silicon-containing monomers as well as of the polyoxadiazoles based on them is described. The properties of these polymers, such as solubility, film forming ability, thermal stability, electrochemical behavior and photoluminescence properties, and their potential applications are discussed.

Development of ceramic composites from mixture of alumina and ceramic precursor polymer poly (silsesquioxane))

International Nuclear Information System (INIS)

Machado, Glauson Aparecido Ferreira

2009-01-01

Processing of ceramics materials, by polymer precursors pyrolysis, has been intensively researched over the past decades, due to advantages that this path provides, such as: lower temperature process compared to conventional techniques; structure control at molecular level; synthesis possibility of a wide range of ceramic compounds; obtaining parts with dimensions of the final product etc. The active filler controlled polymer pyrolysis (AFCOP) process, enables the synthesis of ceramic composites, by reaction between added filler (oxides, metals, intermetallic etc.) and solid and gaseous products, from polymer decomposition. In this study, based on this process, samples of alumina, with addition of 10 and 20 mass% of poly silsesquioxane polymer precursor, were manufactured. These samples were pyrolyzed at 900 degree C and thermal treated at temperatures of 1100, 1300 and 1500 degree C. The samples were characterized for bulk density, porosity and hardness, after each stage of thermal treatment. Structural transformations were analyzed by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. Samples treated until 1300 degree C resulted in composites of alumina and silicon oxycarbide, while those treated at 1500 degree C, formed composites of mullite and alumina. The samples with 20% of polymer added started to density around 800 degree C and high retraction rate was observed at 1400 degree C. (author)

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Skov, Anne Ladegaard

2016-01-01

possesses high dielectric permittivity and consists of an interpenetrating polymer network of silicone elastomer and ionic silicone species that are cross-linked through proton exchange between amines and acids. The ionically cross-linked silicone provides self-healing properties after electrical breakdown...... or cuts made directly to the material due to the reassembly of the ionic bonds that are broken during damage. The dielectric elastomers presented in this paper pave the way to increased lifetimes and the ability of dielectric elastomers to survive millions of cycles in high-voltage conditions....

Three-dimensional patterning in polymer optical waveguides using focused ion beam milling

Science.gov (United States)

Kruse, Kevin; Burrell, Derek; Middlebrook, Christopher

2016-07-01

Waveguide (WG) photonic-bridge taper modules are designed for symmetric planar coupling between silicon WGs and single-mode fibers (SMFs) to minimize photonic chip and packaging footprint requirements with improving broadband functionality. Micromachined fabrication and evaluation of polymer WG tapers utilizing high-resolution focused ion beam (FIB) milling is performed and presented. Polymer etch rates utilizing the FIB and optimal methods for milling polymer tapers are identified for three-dimensional patterning. Polymer WG tapers with low sidewall roughness are manufactured utilizing FIB milling and optically tested for fabrication loss. FIB platforms utilize a focused beam of ions (Ga+) to etch submicron patterns into substrates. Fabricating low-loss polymer WG taper prototypes with the FIB before moving on to mass-production techniques provides theoretical understanding of the polymer taper and its feasibility for connectorization devices between silicon WGs and SMFs.

Origin of electrophosphorescence from a doped polymer light emitting diode

International Nuclear Information System (INIS)

Lane, P. A.; Palilis, L. C.; O'Brien, D. F.; Giebeler, C.; Cadby, A. J.; Lidzey, D. G.; Campbell, A. J.; Blau, W.; Bradley, D. D. C.

2001-01-01

The origin of electrophosphorescence from a doped polymer light emitting diode (LED) has been investigated. A luminescent polymer host, poly(9,9-dioctylfluorene) (PFO), was doped with a red phosphorescent dye, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (PtOEP). The maximum external quantum efficiency of 3.5% was obtained at a concentration of 4% PtOEP by weight. Energy transfer mechanisms between PFO and PtOEP were studied by absorption, photoluminescence, and photoinduced absorption spectroscopy. Even though electroluminescence spectra were dominated by PtOEP at a concentration of only 0.2 wt% PtOEP, Forster transfer of singlet excitons was weak and there was no evidence for Dexter transfer of triplet excitons. We conclude that the dominant emission mechanism in doped LED's is charge trapping followed by recombination on PtOEP molecules

Effects of Shear Fracture on In-depth Profile Modification of Weak Gels

Institute of Scientific and Technical Information of China (English)

Li Xianjie; Song Xinwang; Yue Xiang'an; Hou Jirui; Fang Lichun; Zhang Huazhen

2007-01-01

Two sand packs were filled with fine glass beads and quartz sand respectively. The characteristics of crosslinked polymer flowing through the sand packs as well as the influence of shear fracture of porous media on the in-depth profile modification of the weak gel generated from the crosslinked polymer were investigated. The results indicated that under the dynamic condition crosslinking reaction happened in both sand packs,and the weak gels in these two cases became small gel particles after water flooding. The differences were:the dynamic gelation time in the quartz sand pack was longer than that in the glass bead pack. Residual resistance factor (FRR) caused by the weak gel in the quartz sand pack was smaller than that in the glass bead pack. The weak gel became gel particles after being scoured by subsequent flood water. A weak gel with uniform apparent viscosity and sealing characteristics was generated in every part of the glass bead pack,which could not only move deeply into the sand pack but also seal the high capacity channels again when it reached the deep part. The weak gel performed in-depth profile modification in the glass bead pack,while in the quartz sand pack,the weak gel was concentrated with 100 cm from the entrance of the sand pack. When propelled by the subsequent flood water,the weak gel could move towards the deep part of the sand pack but then became tiny gel particles and could not effectively seal the high capacity channels there. The in-depth profile modification of the weak gel was very weak in the quartz sand pack. It was the shear fracture of porous media that mainly affected the properties and weakened the in-depth profile modification of the weak gel.

Weak polyelectrolyte complexation driven by associative charging

Science.gov (United States)

Rathee, Vikramjit S.; Zervoudakis, Aristotle J.; Sidky, Hythem; Sikora, Benjamin J.; Whitmer, Jonathan K.

2018-03-01

Weak polyelectrolytes are relevant for a wide range of fields; in particular, they have been investigated as "smart" materials for chemical separations and drug delivery. The charges on weak polyelectrolytes are dynamic, causing polymer chains to adopt different equilibrium conformations even with relatively small changes to the surrounding environment. Currently, there exists no comprehensive picture of this behavior, particularly where polymer-polymer interactions have the potential to affect charging properties significantly. In this study, we elucidate the novel interplay between weak polyelectrolyte charging and complexation behavior through coupled molecular dynamics and Monte Carlo simulations. Specifically, we investigate a model of two equal-length and oppositely charging polymer chains in an implicit salt solution represented through Debye-Hückel interactions. The charging tendency of each chain, along with the salt concentration, is varied to determine the existence and extent of cooperativity in charging and complexation. Strong cooperation in the charging of these chains is observed at large Debye lengths, corresponding to low salt concentrations, while at lower Debye lengths (higher salt concentrations), the chains behave in apparent isolation. When the electrostatic coupling is long-ranged, we find that a highly charged chain strongly promotes the charging of its partner chain, even if the environment is unfavorable for an isolated version of that partner chain. Evidence of this phenomenon is supported by a drop in the potential energy of the system, which does not occur at the lower Debye lengths where both potential energies and charge fractions converge for all partner chain charging tendencies. The discovery of this cooperation will be helpful in developing "smart" drug delivery mechanisms by allowing for better predictions for the dissociation point of delivery complexes.

Cryogenic Etching of High Aspect Ratio 400 nm Pitch Silicon Gratings.

Science.gov (United States)

Miao, Houxun; Chen, Lei; Mirzaeimoghri, Mona; Kasica, Richard; Wen, Han

2016-10-01

The cryogenic process and Bosch process are two widely used processes for reactive ion etching of high aspect ratio silicon structures. This paper focuses on the cryogenic deep etching of 400 nm pitch silicon gratings with various etching mask materials including polymer, Cr, SiO 2 and Cr-on-polymer. The undercut is found to be the key factor limiting the achievable aspect ratio for the direct hard masks of Cr and SiO 2 , while the etch selectivity responds to the limitation of the polymer mask. The Cr-on-polymer mask provides the same high selectivity as Cr and reduces the excessive undercut introduced by direct hard masks. By optimizing the etching parameters, we etched a 400 nm pitch grating to ≈ 10.6 μ m depth, corresponding to an aspect ratio of ≈ 53.

Strong quantum-confined stark effect in germanium quantum-well structures on silicon

International Nuclear Information System (INIS)

Kuo, Y.; Lee, Y. K.; Gei, Y.; Ren, S; Roth, J. E.; Miller, D. A.; Harris, J. S.

2006-01-01

Silicon is the dominant semiconductor for electronics, but there is now a growing need to integrate such component with optoelectronics for telecommunications and computer interconnections. Silicon-based optical modulators have recently been successfully demonstrated but because the light modulation mechanisms in silicon are relatively weak, long (for example, several millimeters) devices or sophisticated high-quality-factor resonators have been necessary. Thin quantum-well structures made from III-V semiconductors such as GaAs, InP and their alloys exhibit the much stronger Quantum-Confined Stark Effect (QCSE) mechanism, which allows modulator structures with only micrometers of optical path length. Such III-V materials are unfortunately difficult to integrate with silicon electronic devices. Germanium is routinely integrated with silicon in electronics, but previous silicon-germanium structures have also not shown strong modulation effects. Here we report the discovery of the QCSE, at room temperature, in thin germanium quantum-well structures grown on silicon. The QCSE here has strengths comparable to that in III-V materials. Its clarity and strength are particularly surprising because germanium is an indirect gap semiconductor, such semiconductors often display much weak optical effects than direct gap materials (such as the III-V materials typically used for optoelectronics). This discovery is very promising for small, high-speed, low-power optical output devices fully compatible with silicon electronics manufacture. (author)

Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren

2015-01-01

permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs...... are obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity...

Complex-shaped ceramic composites obtained by machining compact polymer-filler mixtures

Directory of Open Access Journals (Sweden)

Rosa Maria da Rocha

2005-06-01

Full Text Available Research in the preparation of ceramics from polymeric precursors is giving rise to increased interest in ceramic technology because it allows the use of several promising polymer forming techniques. In this work ceramic composite pieces were obtained by pyrolysis of a compacted mixture of a polysiloxane resin and alumina/silicon powder. The mixture consists of 60 vol% of the polymer phase and 40 vol% of the filler in a 1:1 ratio for alumina/silicon, which was hot pressed to crosslink the polymer, thus forming a compact body. This green body was trimmed into different geometries and pyrolised in nitrogen atmosphere at temperatures up to 1600 °C. X-ray diffraction analysis indicated the formation of phases such as mullite and Si2ON2 during pyrolysis, that result from reactions between fillers, polymer decomposition products and nitrogen atmosphere. The porosity was found to be less than 20% and the mass loss around 10%. The complex geometry was maintained after pyrolysis and shrinkage was approximately 8%, proving pyrolisis to be a suitable process to form near-net-shaped bulk ceramic components.

Advances and challenges in the field of plasma polymer nanoparticles

Directory of Open Access Journals (Sweden)

Andrei Choukourov

2017-09-01

Full Text Available This contribution reviews plasma polymer nanoparticles produced by gas aggregation cluster sources either via plasma polymerization of volatile monomers or via radio frequency (RF magnetron sputtering of conventional polymers. The formation of hydrocarbon, fluorocarbon, silicon- and nitrogen-containing plasma polymer nanoparticles as well as core@shell nanoparticles based on plasma polymers is discussed with a focus on the development of novel nanostructured surfaces.

Probing the surface properties of a polymer glass with macroscopic friction

International Nuclear Information System (INIS)

Bureau, Lionel

2007-01-01

We show how macroscopic friction can be used as a sensitive probe of chain dynamics at the surface of a glassy polymer. We present experiments in which a smooth poly(methylmethacrylate) (PMMA) solid slides on flat surfaces presenting different densities of pinning sites available for polymer/substrate bond formation. These experiments indicate that: (i) at high pinning level, frictional dissipation occurs through the sudden flips of molecular-sized bistable regions localized in a nm-thick layer of confined chains, which responds to shear as an elasto-plastic solid, and (ii) in situations of weak pinning, dissipation appears to be governed by a process akin to that proposed for rubber friction. This suggests that some 'glass-to-rubber' transition occurs at the polymer surface when its interaction with the substrate goes from strong to weak. The temperature-dependence of friction provides further support for the presence of a nm-thick layer at the polymer surface, which exhibits a rubberlike response in situation of weak interaction with the countersurface. This behavior results from the interplay between viscous flow in this surface layer, and shear induced depinning of adsorbed surface chains. Moreover, a quantitative analysis of the results indicates that the pinning dynamics of polymer chains is controlled by localized β rotational motions at the interface

Efficient tunable luminescence of SiGe alloy sheet polymers

International Nuclear Information System (INIS)

Vogg, G.; Meyer, A. J.-P.; Miesner, C.; Brandt, M. S.; Stutzmann, M.

2001-01-01

Crystalline SiGe alloy sheet polymers were topotactically prepared from epitaxially grown calcium germanosilicide Ca(Si 1-x Ge x ) 2 precursor films in the whole composition range. These polygermanosilynes are found to be a well-defined mixture of the known siloxene and polygermyne sheet polymers with the OH groups exclusively bonded to silicon. The optical properties determined by photoluminescence and optical reflection measurements identify the mixed SiGe sheet polymers as direct semiconductors with efficient luminescence tunable in the energy range between 2.4 and 1.3 eV. [copyright] 2001 American Institute of Physics

Fiscal 1997 project on the R and D of industrial scientific technology under consignment from NEDO. Report on the results of the R and D of silicon-based polymeric materials (development of liquid methane fueled aircraft engine); 1997 nendo sangyo kagaku gijutsu kenkyu kaihatsu jigyo / Shin energy Sangyo gijutsu Sogo Kaihatsu Kiko itaku. Keisokei kobunshi zairyo no kenkyu kaihatsu (methane nenryo kokukiyo engine kaihatsu) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

This R and D aims at establishing the basic technology on the molecular design, synthesis, use as materials, and evaluation of silicon-based polymers, of which excellent electronic/optical functions, high heat-resistance/combustion-resistance/dynamic characteristic are expected. The paper introduced the results of the fiscal 1997 R and D of them. The themes are as follows: technology of synthesis of silicon-based polymeric materials with sea-island microstructures, interstitial type structure forming technology, composite materials with organometallic complexes and silicon-based polymers, silicon-based polymer structural materials with ring structures, optimization of the Wurtz`s synthesis method of silicon-based polymers, unsaturated and hypercoordinate organosilicic compounds, function of silicon-based polymers, synthesis and polymerization of new silicon-based monomers, development of a new synthesis method of polysilane and the function, development of new application of silicon-based polymers in imaging devices for recording/memory/display of information, molecular design of {pi}-conjugate and {sigma}-conjugate compounds including silicon, and conformation and electronic state of silicon-based polymeric materials. 186 refs., 141 figs., 68 tabs.

Multifunctional microstructured polymer films for boosting solar power generation of silicon-based photovoltaic modules.

Science.gov (United States)

Leem, Jung Woo; Choi, Minkyu; Yu, Jae Su

2015-02-04

We propose two-dimensional periodic conical micrograting structured (MGS) polymer films as a multifunctional layer (i.e., light harvesting and self-cleaning) at the surface of outer polyethylene terephthalate (PET) cover-substrates for boosting the solar power generation in silicon (Si)-based photovoltaic (PV) modules. The surface of ultraviolet-curable NOA63 MGS polymer films fabricated by the soft imprint lithography exhibits a hydrophobic property with water contact angle of ∼121° at no inclination and dynamic advancing/receding water contact angles of ∼132°/111° at the inclination angle of 40°, respectively, which can remove dust particles or contaminants on the surface of PV modules in real outdoor environments (i.e., self-cleaning). The NOA63 MGS film coated on the bare PET leads to the reduction of reflection as well as the enhancement of both the total and diffuse transmissions at wavelengths of 300-1100 nm, indicating lower solar weighted reflectance (RSW) of ∼8.2%, higher solar weighted transmittance (TSW) of ∼93.1%, and considerably improved average haze ratio (HAvg) of ∼88.3% as compared to the bare PET (i.e., RSW ≈ 13.5%, TSW ≈ 86.9%, and HAvg ≈ 9.1%), respectively. Additionally, it shows a relatively good durability at temperatures of ≤160 °C. The resulting Si PV module with the NOA63 MGS/PET has an enhanced power conversion efficiency (PCE) of 13.26% (cf., PCE = 12.55% for the reference PV module with the bare PET) due to the mainly improved short circuit current from 49.35 to 52.01 mA, exhibiting the PCE increment percentage of ∼5.7%. For light incident angle-dependent PV module current-voltage characteristics, superior solar energy conversion properties are also obtained in a broad angle range of 10-80°.

XANES at the silicon k-edge in the kaolin-meta kaolin-geopolymer system

International Nuclear Information System (INIS)

Lima, F.T.; Silva, F.J.; Thaumaturgo, C.

2005-01-01

The geo polymer synthesis process optimization pretends to control the re logical and mechanical properties. The Al/Si ratio is the main variable that governs the geo polymerization process. This control occurs by changing temperature, pressure and chemical composition of the geo polymer. Thermal analysis (DTA/DSC), microscopic (SEM/TEM) and spectroscopic (FTIR, XRD, SAXS, EXAFS and XANES) techniques have been used to characterize these inorganic systems. In this work, XANES spectra of the k-edge silicon (Si) of the kaolin-meta kaolin-geo polymer are presented. The XANES spectra provides the oxidation state and structural information about the present studied atom: Silicon (Si). (author)

Chemical and structural properties of polymorphous silicon thin films grown from dichlorosilane

Energy Technology Data Exchange (ETDEWEB)

Álvarez-Macías, C.; Monroy, B.M.; Huerta, L.; Canseco-Martínez, M.A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico); Picquart, M. [Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, A.P. 55-534, 09340 México, D.F. (Mexico); Santoyo-Salazar, J. [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, C.P. 07000 México, D.F. (Mexico); Sánchez, M.F. García [Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. I.P.N. 2580, Gustavo A. Madero, 07340 México .D.F. (Mexico); Santana, G., E-mail: gsantana@iim.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico)

2013-11-15

We have examined the effects of hydrogen dilution (R{sub H}) and deposition pressure on the morphological, structural and chemical properties of polymorphous silicon thin films (pm-Si:H), using dichlorosilane as silicon precursor in the plasma enhanced chemical vapor deposition (PECVD) process. The use of silicon chlorinated precursors enhances the crystallization process in as grown pm-Si:H samples, obtaining crystalline fractions from Raman spectra in the range of 65–95%. Atomic Force Microscopy results show the morphological differences obtained when the chlorine chemistry dominates the growth process and when the plasma–surface interactions become more prominent. Augmenting R{sub H} causes a considerable reduction in both roughness and topography, demonstrating an enhancement of ion bombardment and attack of the growing surface. X-ray Photoelectron Spectroscopy results show that, after ambient exposure, there is low concentration of oxygen inside the films grown at low R{sub H}, present in the form of Si-O, which can be considered as structural defects. Instead, oxidation increases with deposition pressure and dilution, along with film porosity, generating a secondary SiO{sub x} phase. For higher pressure and dilution, the amount of chlorine incorporated to the film decreases congruently with HCl chlorine extraction processes involving atomic hydrogen interactions with the surface. In all cases, weak silicon hydride (Si-H) bonds were not detected by infrared spectroscopy, while bonding configurations associated to the silicon nanocrystal surface were clearly observed. Since these films are generally used in photovoltaic devices, analyzing their chemical and structural properties such as oxygen incorporation to the films, along with chlorine and hydrogen, is fundamental in order to understand and optimize their electrical and optical properties.

Nanocomposites Based on Polyethylene and Nanocrystalline Silicon Films

Directory of Open Access Journals (Sweden)

Olkhov Anatoliy Aleksandrovich

2014-12-01

Full Text Available High-strength polyethylene films containing 0.5-1.0 wt. % of nanocrystalline silicon (nc-Si were synthesized. Samples of nc-Si with an average core diameter of 7-10 nm were produced by plasmochemical method and by laser-induced decomposition of monosilane. Spectral studies revealed almost complete (up to ~95 % absorption of UV radiation in 200- 400 nm spectral region by 85 micron thick film if the nc-Si content approaches to 1.0 wt. %. The density function of particle size in the starting powders and polymer films containing immobilized silicon nanocrystallites were obtained using the modeling a complete profile of X-ray diffraction patterns, assuming spherical grains and the lognormal distribution. The results of X-ray analysis shown that the crystallite size distribution function remains almost unchanged and the crystallinity of the original polymer increases to about 10 % with the implantation of the initial nc-Si samples in the polymer matrix.

Photopolymerizable silicone monomers, oligomers, and resins

International Nuclear Information System (INIS)

Jacobine, A.F.; Nakos, S.T.

1992-01-01

The purpose of this chapter is to acquaint the general photopolymer researcher with the historical development of the chemistry and technology of photopolymerizable silicone monomers, fluids, and resins. The current status of research in these areas is assessed. The focus of this chapter is not only on the polymer chemistry and application of this technology, but also on important aspects of the synthetic chemistry involved in the preparation of UV-curable silicone monomers, oligomers, and resins. 236 refs., 6 tabs

Novel processing of bioglass ceramics from silicone resins containing micro- and nano-sized oxide particle fillers.

Science.gov (United States)

Fiocco, L; Bernardo, E; Colombo, P; Cacciotti, I; Bianco, A; Bellucci, D; Sola, A; Cannillo, V

2014-08-01

Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained samples possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests. © 2013 Wiley Periodicals, Inc.

Electrochemical properties of ion implanted silicon

International Nuclear Information System (INIS)

Pham minh Tan.

1979-11-01

The electrochemical behaviour of ion implanted silicon in contact with hydrofluoric acid solution was investigated. It was shown that the implanted layer on silicon changes profoundly its electrochemical properties (photopotential, interface impedance, rest potential, corrosion, current-potential behaviour, anodic dissolution of silicon, redox reaction). These changes depend strongly on the implantation parameters such as ion dose, ion energy, thermal treatment and ion mass and are weakly dependent on the chemical nature of the implantation ion. The experimental results were evaluated and interpreted in terms of the semiconductor electrochemical concepts taking into account the interaction of energetic ions with the solid surface. The observed effects are thus attributed to the implantation induced damage of silicon lattice and can be used for profiling of the implanted layer and the electrochemical treatment of the silicon surface. (author)

Optical and rheological studies on weak gel-sol transition in aqueous solutions of poly(N-isopropylacrylamide-block-polystyrene

Directory of Open Access Journals (Sweden)

S. Sanjeevi Prasath

2017-07-01

Full Text Available The optical and rheological properties of aqueous solutions of block copolymer composed of low molecular weight poly(N-isopropylacrylamide-b-polystyrene are studied as a function of temperature. From light scattering measurements the block copolymer solution is found to form micelles at very low concentrations and the critical micellar concentration is identified as 0.005 wt%. Apart from the concentration dependence, a unique temperature dependent micelle formation is noted at 34 °C. Further, temperature dependent refractive index measurements shows that the refractive index increases with temperature (beyond the lower critical solution temperature, 31.6 °C of the polymer, and is attributed to the stable rearrangement of the proximal hydrophobic isopropyl-polystyrene chains in the collapsed polymer so as to overcome the steric hindrance effects offered by the hydrophobic chains. In the polymer concentrations investigated for rheological studies, the solution flows, yet manifested solid like behavior with G' > G" with the modulus being frequency dependent and the magnitude of G' two-fold higher than G" implying a weak gel state. Weak gel states are in general noted at high temperatures in most of the polymer systems, contrary to this, in our studies weak gel state is observed at lower temperature. Further, a transition from weak gel to sol state is observed at slightly elevated temperatures. The reason for the existence of weak gel state below the lower critical solution temperature is due to the micellar entanglements of poly(N-isopropylacrylamide-b-polystyrene with one another and whereas above the lower critical solution temperature disentanglement of the micelles makes the system behave like a viscoelastic liquid.

Preparation And Characterization Of Silicon Carbide Foam By Using In-Situ Generated Polyurethane Foam

Directory of Open Access Journals (Sweden)

Shalini Saxena

2015-08-01

Full Text Available Abstract The open cell silicon carbide SiC foam was prepared using highly crosslinked hybrid organic- inorganic polymer resin matrix. As inorganic polymer polycarbosilane was taken and organic resin was taken as a mixture of epoxy resin and diisocyanates. The resultant highly crosslinked hybrid resin matrix on heating and subsequently on pyrolysis yielded open cell silicon carbide foam. The hybrid resin matrix was characterized by Fourier transform Infrared Spectroscopy FT-IR and thermal properties i.e. Thermogravimetric analysis TGA amp Differential Scanning Calorimetry DSC were also studied. The morphological studies of silicon carbide ceramic foam were carried out using X-ray Spectroscopy XRD amp Scanning Electron Microscopy SEM.

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.

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

Fabrication of disposable topographic silicon oxide from sawtoothed patterns: control of arrays of gold nanoparticles.

Science.gov (United States)

Cho, Heesook; Yoo, Hana; Park, Soojin

2010-05-18

Disposable topographic silicon oxide patterns were fabricated from polymeric replicas of sawtoothed glass surfaces, spin-coating of poly(dimethylsiloxane) (PDMS) thin films, and thermal annealing at certain temperature and followed by oxygen plasma treatment of the thin PDMS layer. A simple imprinting process was used to fabricate the replicated PDMS and PS patterns from sawtoothed glass surfaces. Next, thin layers of PDMS films having different thicknesses were spin-coated onto the sawtoothed PS surfaces and annealed at 60 degrees C to be drawn the PDMS into the valley of the sawtoothed PS surfaces, followed by oxygen plasma treatment to fabricate topographic silicon oxide patterns. By control of the thickness of PDMS layers, silicon oxide patterns having various line widths were fabricated. The silicon oxide topographic patterns were used to direct the self-assembly of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films via solvent annealing process. A highly ordered PS-b-P2VP micellar structure was used to let gold precursor complex with P2VP chains, and followed by oxygen plasma treatment. When the PS-b-P2VP thin films containing gold salts were exposed to oxygen plasma environments, gold salts were reduced to pure gold nanoparticles without changing high degree of lateral order, while polymers were completely degraded. As the width of trough and crest in topographic patterns increases, the number of gold arrays and size of gold nanoparticles are tuned. In the final step, the silicon oxide topographic patterns were selectively removed by wet etching process without changing the arrays of gold nanoparticles.

Report for fiscal 1998 on results of research and development of silicon-based polymeric material. Material research for the liquid methane fueled aircraft engine; 1998 nendo keisokei kobunshi zairyo no kenkyu kaihatsu seika hokokusho. Methane nenryo kokukiyo engine kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

Research was conducted for the purpose of establishing basic technology concerning molecular design, synthesis, material formation, and evaluation of silicon-based polymers which are expected to provide superior electronic/optical functions, high heat/combustion resistance and dynamic properties. The research subjects were such as following: research and development of silicon-based polymeric materials with sea-island microstructures; research and development of silicon-based polymeric materials with sea-island microstructures; research and development on IPN formation with silicon-based polymers; research and development of hybrid silicon polymers with organometallic compounds; research and development of silicon containing polymer materials with ring structures; general committee for investigation and research; the optimized low-temperature Wurtz synthesis and modification of polysilanes; study of unsaturated and hypercoordinate organosilicon compounds; basic studies on the synthesis and properties of silicon-based high polymers; studies of new monomer-synthesis and their polymerization reaction; studies on new method of preparation and functionalization of polysilanes; novel applications of silicon-based polymers in imaging devices for information display, memory, and recordings; and molecular design of silicon-containing {pi}-conjugated and {sigma}-conjugated compounds. (NEDO)

Ballistic nanoindentation of polymers

Science.gov (United States)

Gotsmann, B.; Rothuizen, H.; Duerig, U.

2008-09-01

Indentation of a sharp (20 nm) cantilevered silicon tip into a polymer (SU8) surface is analyzed experimentally and through finite-element simulations. A rate effect on the microsecond scale that eases indentation is found, in contrast to the commonly observed hardening at high strain rates. The observed rate effect is discussed in terms of adiabatic heating and inertial force overshoot. The estimated magnitude of adiabatic heating is marginal, but the force overshoot itself is large enough to explain the data. The data imply that topographic patterning of a polymer at megahertz rates is feasible.

Self-organized dendritic patterns in the polymer Langmuir-Blodgett film

Energy Technology Data Exchange (ETDEWEB)

Matsui, Jun, E-mail: jun_m@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan); Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi 332-0012 (Japan); Suzuki, Toshio; Mikayama, Takeshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan); Aoki, Atsushi [Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Shouwa-ku, Nagoya 466-8555 (Japan); Miyashita, Tokuji [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan)

2011-01-03

We report the formation of a self-organized dendritic pattern of nanometer thickness in polymer Langmuir-Blodgett (LB) films. Poly(N-dodecylacrylamide) (pDDA)/chloroform solution was spread on a water surface to form a stable polymer monolayer. A pDDA monolayer was deposited onto a hydrophilic silicon substrate by upward deposition from a water subphase, and a second layer was then deposited by downward deposition. The substrate with the two layers was withdrawn from a clean water surface at a high speed to form the dendritic pattern, which was imaged by atomic force microscopy. The height of the pattern, 3.5 nm, corresponds to the height of a bilayer pDDA LB film, suggesting that the pattern forms when the deposited outermost layer overturns by meniscus oscillation. A similar dendritic structure of narrower width and lower height was fabricated on a hydrophobic silicon substrate.

Electronically conductive polymer binder for lithium-ion battery electrode

Energy Technology Data Exchange (ETDEWEB)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

2017-08-01

A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Electronically conductive polymer binder for lithium-ion battery electrode

Science.gov (United States)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

2015-07-07

A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Green silicone elastomer obtained from a counterintuitively stable mixture of glycerol and PDMS

DEFF Research Database (Denmark)

Mazurek, P.; Hvilsted, S.; Skov, A. L.

2016-01-01

A green and cheap silicone-based elastomer has been developed. Through the simple mixing-in of biodiesel-originating glycerol into commercially available polydimethylsiloxane (PDMS) pre-polymer, a glycerol-in-PDMS emulsion was produced. This counterintuitively stable mixture became a basis...... for obtaining elastomeric composites with uniformly distributed glycerol droplets. Various compositions, containing from 0 to 140 parts of glycerol per 100 parts of PDMS by weight, were prepared and investigated in terms of ATR-FTIR, broadband dielectric spectroscopy, mechanical properties as well as optical......, even in the presence of very high loadings. The conducted experiments highlight the great potential of this new type of elastomer and reveal some possible applications....

Chemical and Sensory Evaluation of Silicone and Polylactic Acid-Based Remedial Treatments for Elevated Methoxypyrazine Levels in Wine

Directory of Open Access Journals (Sweden)

Andreea Botezatu

2016-09-01

Full Text Available Alkylmethoxypyrazines (MPs are a class of compounds that can elicit undesirable aroma and flavor characteristics in wine, and resist remediation using traditional wine making approaches. MPs are grape-derived constituents as well as contaminants from Coccinellidae beetles present during wine processing; the latter eliciting an off-flavor referred to as ‘ladybug taint’. In this study we investigated the capacity of two plastic polymers—one silicone-based, the other polylactic acid-based—applied with varying surface areas to reduce concentrations of isopropylmethoxypyrazine (IPMP, sec-butylmethoxypyrazine (SBMP and isobutylmethoxypyrazine (IBMP in a Merlot wine using multi-dimensional gas chromatography coupled with mass spectrometry and headspace solid phase microextraction (SPME-MDGCMS. The impact of treatments on the sensory characteristics of the wine (descriptive analysis and volatile aroma compounds (VOCs (SPME-MDGCMS was also investigated. Results showed substantial reductions for all of the target odorants: up to 38%, 44% and 39% for IPMP, SBMP and IBMP, respectively, for the silicone polymer, and up to 75%, 78% and 77% for IPMP, SBMP and IBMP, respectively, for the polylactic acid polymer. These polymers had no or minimal effect on VOCs at applications of 200 cm2/L for silicone or for all polylactic acid treatments. Sensory impacts were less clear, but generally showed minimal effect from the treatments. Taken overall, the data confirm the utility of both polylactic acid and silicone polymers in reducing elevated levels of grape-derived MPs, as well as potentially improving wine contaminated by ladybug taint.

Preservation of atomically clean silicon surfaces in air by contact bonding

DEFF Research Database (Denmark)

Grey, Francois; Ljungberg, Karin

1997-01-01

When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find that the or...... reconstruction from oxidation in air, Contact bonding opens the way to novel applications of reconstructed semiconductor surfaces, by preserving their atomic structure intact outside of a UHV chamber. (C) 1997 American Institute of Physics.......When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find...... that the ordered atomic structure of the surfaces is protected from oxidation, even after the bonded samples have been in air for weeks. Further, we show that silicon surfaces that have been cleaned and hydrogen-passivated in UHV can be contacted in UHV in a similarly hermetic fashion, protecting the surface...

Highly sensitive polymer-based cantilever-sensors for DNA detection

International Nuclear Information System (INIS)

Calleja, M.; Nordstroem, M.; Alvarez, M.; Tamayo, J.; Lechuga, L.M.; Boisen, A.

2005-01-01

We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers

Glass transition temperature of polymer nano-composites with polymer and filler interactions

Science.gov (United States)

Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

2012-02-01

We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

DC breakdown characteristics of silicone polymer composites for HVDC insulator applications

Science.gov (United States)

Han, Byung-Jo; Seo, In-Jin; Seong, Jae-Kyu; Hwang, Young-Ho; Yang, Hai-Won

2015-11-01

Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.

Monolithic amorphous silicon modules on continuous polymer substrate. Final subcontract report, 9 January 1991--14 April 1991

Energy Technology Data Exchange (ETDEWEB)

Grimmer, D.P. [Iowa Thin Film Technologies, Inc., Ames, IA (US)

1992-03-01

This report examines manufacturing monolithic amorphous silicon modules on a continuous polymer substrate. Module production costs can be reduced by increasing module performance, expanding production, and improving and modifying production processes. Material costs can be reduced by developing processes that use a 1-mil polyimide substrate and multilayers of low-cost material for the front encapsulant. Research to speed up a-Si and ZnO deposition rates is needed to improve throughputs. To keep throughput rates compatible with depositions, multibeam fiber optic delivery systems for laser scribing can be used. However, mechanical scribing systems promise even higher throughputs. Tandem cells and production experience can increase device efficiency and stability. Two alternative manufacturing processes are described: (1) wet etching and sheet handling and (2) wet etching and roll-to-roll fabrication.

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

OpenAIRE

Zhuhao Gong; Yulong Zhang; Xin Guo; Zewen Liu

2018-01-01

A radio-frequency micro-electro-mechanical system (RF MEMS) wafer-level packaging (WLP) method using pre-patterned benzo-cyclo-butene (BCB) polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to gener...

Silicon Nanowire/Polymer Hybrid Solar Cell-Supercapacitor: A Self-Charging Power Unit with a Total Efficiency of 10.5.

Science.gov (United States)

Liu, Ruiyuan; Wang, Jie; Sun, Teng; Wang, Mingjun; Wu, Changsheng; Zou, Haiyang; Song, Tao; Zhang, Xiaohong; Lee, Shuit-Tong; Wang, Zhong Lin; Sun, Baoquan

2017-07-12

An integrated self-charging power unit, combining a hybrid silicon nanowire/polymer heterojunction solar cell with a polypyrrole-based supercapacitor, has been demonstrated to simultaneously harvest solar energy and store it. By efficiency enhancement of the hybrid nanowire solar cells and a dual-functional titanium film serving as conjunct electrode of the solar cell and supercapacitor, the integrated system is able to yield a total photoelectric conversion to storage efficiency of 10.5%, which is the record value in all the integrated solar energy conversion and storage system. This system may not only serve as a buffer that diminishes the solar power fluctuations from light intensity, but also pave its way toward cost-effective high efficiency self-charging power unit. Finally, an integrated device based on ultrathin Si substrate is demonstrated to expand its feasibility and potential application in flexible energy conversion and storage devices.

Atomic Origins of the Self-Healing Function in Cement–Polymer Composites

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Manh Thuong; Wang, Zheming; Rod, Kenton A.; Childers, Matthew I.; Fernandez, Carlos A.; Koech, Phillip K.; Bennett, Wendy D.; Rousseau, Roger J.; Glezakou, Vassiliki-Alexandra

2018-01-09

Motivated by recent advances in self-healing cement and epoxy polymer composites, we present a combined ab initio molecular dynamics and sum frequency generation (SFG) spectroscopy study of a calcium-silicate-hydrate/polymer interface. On stable, low-defect surfaces, the polymer only weakly adheres through coordination and hydrogen bonding interactions and can be easily mobilized towards defected surfaces. Conversely, on fractured surfaces, the polymer strongly anchors through ionic Ca-O bonds resulting from the deprotonation of polymer hydroxyl groups. In addition, polymer S-S groups are turned away from the cement/polymer interface, allowing for the self-healing function within the polymer. The overall elasticity and healing properties of these composites stem from a flexible hydrogen bonding network that can readily adapt to surface morphology. The theoretical vibrational signals associated with the proposed cement-polymer interfacial chemistry were confirmed experimentally by SFG spectroscopy.

A Space Experiment to Measure the Atomic Oxygen Erosion of Polymers and Demonstrate a Technique to Identify Sources of Silicone Contamination

Science.gov (United States)

Banks, Bruce A.; deGroh, Kim K.; Baney-Barton, Elyse; Sechkar, Edward A.; Hunt, Patricia K.; Willoughby, Alan; Bemer, Meagan; Hope, Stephanie; Koo, Julie; Kaminski, Carolyn;

Core/shell silicon/polyaniline particles via in-flight plasma-induced polymerization

International Nuclear Information System (INIS)

Yasar-Inceoglu, Ozgul; Mangolini, Lorenzo; Zhong, Lanlan

2015-01-01

Although silicon nanoparticles have potential applications in many relevant fields, there is often the need for post-processing steps to tune the property of the nanomaterial and to optimize it for targeted applications. In particular surface modification is generally necessary to both tune dispersibility of the particles in desired solvents to achieve optimal coating conditions, and to interface the particles with other materials to realize functional heterostructures. In this contribution we discuss the realization of core/shell silicon/polymer nanoparticles realized using a plasma-initiated in-flight polymerization process. Silicon particles are produced in a non-thermal plasma reactor using silane as a precursor. After synthesis they are aerodynamically injected into a second plasma reactor into which aniline vapor is introduced. The second plasma initiates the polymerization reactor leading to the formation of a 3–4 nm thick polymer shell surrounding the silicon core. The role of processing conditions on the properties of the polymeric shell is discussed. Preliminary results on the testing of this material as an anode for lithium ion batteries are presented. (paper)

Core/shell silicon/polyaniline particles via in-flight plasma-induced polymerization

Science.gov (United States)

Yasar-Inceoglu, Ozgul; Zhong, Lanlan; Mangolini, Lorenzo

2015-08-01

Although silicon nanoparticles have potential applications in many relevant fields, there is often the need for post-processing steps to tune the property of the nanomaterial and to optimize it for targeted applications. In particular surface modification is generally necessary to both tune dispersibility of the particles in desired solvents to achieve optimal coating conditions, and to interface the particles with other materials to realize functional heterostructures. In this contribution we discuss the realization of core/shell silicon/polymer nanoparticles realized using a plasma-initiated in-flight polymerization process. Silicon particles are produced in a non-thermal plasma reactor using silane as a precursor. After synthesis they are aerodynamically injected into a second plasma reactor into which aniline vapor is introduced. The second plasma initiates the polymerization reactor leading to the formation of a 3-4 nm thick polymer shell surrounding the silicon core. The role of processing conditions on the properties of the polymeric shell is discussed. Preliminary results on the testing of this material as an anode for lithium ion batteries are presented.

Photonic porous silicon as a pH sensor.

Science.gov (United States)

Pace, Stephanie; Vasani, Roshan B; Zhao, Wei; Perrier, Sébastien; Voelcker, Nicolas H

2014-01-01

Chronic wounds do not heal within 3 months, and during the lengthy healing process, the wound is invariably exposed to bacteria, which can colonize the wound bed and form biofilms. This alters the wound metabolism and brings about a change of pH. In this work, porous silicon photonic films were coated with the pH-responsive polymer poly(2-diethylaminoethyl acrylate). We demonstrated that the pH-responsive polymer deposited on the surface of the photonic film acts as a barrier to prevent water from penetrating inside the porous matrix at neutral pH. Moreover, the device demonstrated optical pH sensing capability visible by the unaided eye.

Electronically conductive polymer binder for lithium-ion battery electrode

Energy Technology Data Exchange (ETDEWEB)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe

2017-05-16

A family of carboxylic acid group containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Thiolated silicone oil: Synthesis, gelling and mucoadhesive properties

Science.gov (United States)

Partenhauser, Alexandra; Laffleur, Flavia; Rohrer, Julia; Bernkop-Schnürch, Andreas

2015-01-01

The aim of this study was the development of novel thiolated silicone oils and their evaluation with regard to gelling and mucoadhesive properties. A thiol coupling of 220 ± 14 and 127 ± 33 μmol/g polymer for 3-mercaptopropionic acid (MPA)- and cysteine-coupled silicone oil was determined, respectively. The dynamic viscosity of MPA–silicone raised significantly (p Thiolated silicone oils can be regarded superior in comparison to commonly used silicone oils due to a prolonged retention time in the small intestine as site of action. Gelling and mucoadhesive features are advantageous for antiflatulent as well as mucoprotective biomaterials. Thus, these novel thiomers seem promising for an upgrade of currently available products for the treatment of dyspepsia, reflux oesophagitis and even inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease. PMID:25660565

Investigation of polymer derived ceramics cantilevers for application of high speed atomic force microscopy

Science.gov (United States)

Wu, Chia-Yun

High speed Atomic Force Microscopy (AFM) has a wide variety of applications ranging from nanomanufacturing to biophysics. In order to have higher scanning speed of certain AFM modes, high resonant frequency cantilevers are needed; therefore, the goal of this research is to investigate using polymer derived ceramics for possible applications in making high resonant frequency AFM cantilevers using complex cross sections. The polymer derived ceramic that will be studied, is silicon carbide. Polymer derived ceramics offer a potentially more economic fabrication approach for MEMS due to their relatively low processing temperatures and ease of complex shape design. Photolithography was used to make the desired cantilever shapes with micron scale size followed by a wet etching process to release the cantilevers from the substrates. The whole manufacturing process we use borrow well-developed techniques from the semiconducting industry, and as such this project also could offer the opportunity to reduce the fabrication cost of AFM cantilevers and MEMS in general. The characteristics of silicon carbide made from the precursor polymer, SMP-10 (Starfire Systems), were studied. In order to produce high qualities of silicon carbide cantilevers, where the major concern is defects, proper process parameters needed to be determined. Films of polymer derived ceramics often have defects due to shrinkage during the conversion process. Thus control of defects was a central issue in this study. A second, related concern was preventing oxidation; the polymer derived ceramics we chose is easily oxidized during processing. Establishing an environment without oxygen in the whole process was a significant challenge in the project. The optimization of the parameters for using photolithography and wet etching process was the final and central goal of the project; well established techniques used in microfabrication were modified for use in making the cantilever in the project. The techniques

Structure analysis of adsorbed star-like polymers with GISAS and SFM

CERN Document Server

Wolkenhauer, M; Wunnicke, O; Stamm, M; Roovers, J; Krosigk, G V; Cubitt, R

2002-01-01

The lateral structures of dried adsorbed binary mixtures of star polymers were investigated. Blends of protonated and deuterated polybutadiene stars were prepared from cyclohexane solutions and adsorbed onto silicon substrates. The number of arms and the molecular weight of the arms was varied. With grazing incidence small angle scattering techniques (GISAS) and scanning force microscopy (SFM), different dominant in-plane length scales were determined. The morphology of these structures is dominated by blob-like structures created from single stars or agglomerates of star polymers. (orig.)

Highly sensitive polymer-based cantilever-sensors for DNA detection

Energy Technology Data Exchange (ETDEWEB)

Calleja, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain) and Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)]. E-mail: mcalleja@imm.cnm.csic.es; Nordstroem, M. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark); Alvarez, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Tamayo, J. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Lechuga, L.M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Boisen, A. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)

2005-11-15

We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers.

Electrodialysis separation of rhenium from silicon

International Nuclear Information System (INIS)

Prasolova, O.D.; Borisova, L.V.; Ermakov, A.N.

1989-01-01

A method of separation of ruthenium from silicon by electrodialysis with heterogenuos ion-exchange membranes is developed. The effeciency of purification of rhenium from silicon depending on the number of dialyzer chambers, temperature and pH value of the dialyzate is studed. It is found that an addditional fourth chamber between the middle and anolytic ones causes the purification coefficient increase 50 times. It is necessary to cool the dialyzate in order to reduce silicon migration into the anolyte and reverse diffusion of perrhenate-ion from the anolyte into the dialyzate. The optimal pH value of diaizate is 5.5-6. The method developed has been used for separating rhenium from industrial solution of lead production with complex composition

Space Flight Experiments to Measure Polymer Erosion and Contamination on Spacecraft

Science.gov (United States)

Lillis, Maura C.; Youngstrom, Erica E.; Marx, Laura M.; Hammerstrom, Anne M.; Finefrock, Katherine D.; Youngstrom, Christiane A.; Kaminski, Carolyn; Fine, Elizabeth S.; Hunt, Patricia K.; deGroh, Kim K.

2002-01-01

Atomic oxygen erosion and silicone contamination are serious issues that could damage or destroy spacecraft components after orbiting for an extended period of time, such as on a space station or satellite. An experiment, the Polymer Erosion And Contamination Experiment (PEACE) will be conducted to study the effects of atomic oxygen (AO) erosion and silicone contamination, and it will provide information and contribute to a solution for these problems. PEACE will fly 43 different polymer materials that will be analyzed for AO erosion effects through two techniques: mass loss measurement and recession depth measurement. Pinhole cameras will provide information about the arrival direction of AO, and silicone contamination pinhole cameras will identify the source of silicone contamination on a spacecraft. All experimental hardware will be passively exposed to AO for up to two weeks in the actual space environment when it flies in the bay of a space shuttle. A second set of the PEACE Polymers is being exposed to the space environment for erosion yield determination as part of a second experiment, Materials International Space Station Experiment (MISSE). MISSE is a collaboration between several federal agencies and aerospace companies. During a space walk on August 16, 2001, MISSE was attached to the outside of the International Space Station (ISS) during an extravehicular activity (EVA), where it began its exposure to AO for approximately 1.5 years. The PEACE polymers, therefore, will be analyzed after both short-term and long-term AO exposures for a more complete study of AO effects.

Ultrathin Polymer Films, Patterned Arrays, and Microwells

Science.gov (United States)

Yan, Mingdi

2002-05-01

The ability to control and tailor the surface and interface properties of materials is important in microelectronics, cell growth control, and lab-on-a-chip devices. Modification of material surfaces with ultrathin polymer films is attractive due to the availability of a variety of polymers either commercially or by synthesis. We have developed two approaches to the attachment of ultrathin polymer films on solid substrates. In the first method, a silane-functionalized perfluorophenyl azide (PFPA-silane) was synthesized and used to covalently immobilize polymer thin films on silicon wafers. Silanization of the wafer surface with the PFPA-silane introduced a monolayer of azido groups which in turn covalently attached the polymer film by way of photochemically initiated insertion reactions. The thickness of the film could be adjusted by the type and the molecular weight of the polymer. The method is versatile due to the general C-H and/or N-H insertion reactions of crosslinker; and therefore, no specific reactive functional groups on the polymers are required. Using this method, a new type of microwell array was fabricated from covalently immobilized polymer thin films on flat substrates. The arrays were characterized with AFM, XPS, and TOF-SIMS. The second method describes the attachment of polymer thin films on solid substrates via UV irradiation. The procedure consisted of spin-coating a polymer film and irradiating the film with UV light. Following solvent extraction, a thin film remained. The thickness of the film, from a few to over a hundred nanometers, was controlled by varying solution concentration and the molecular weight of the polymer.

Development of test models to quantify encapsulated bioburden in spacecraft polymer materials by cultivation-dependent and molecular methods

Science.gov (United States)

Bauermeister, Anja; Moissl-Eichinger, Christine; Mahnert, Alexander; Probst, Alexander; Flier, Niwin; Auerbach, Anna; Weber, Christina; Haberer, Klaus; Boeker, Alexander

Bioburden encapsulated in spacecraft polymers (such as adhesives and coatings) poses a potential risk to scientific exploration of other celestial bodies, but it is not easily detectable. In this study, we developed novel testing strategies to estimate the quantity of intrinsic encapsulated bioburden in polymers used frequently on spaceflight hardware. In particular Scotch-Weld (TM) 2216 B/A (Epoxy adhesive); MAP SG121FD (Silicone coating), Solithane (®) 113 (Urethane resin); ESP 495 (Silicone adhesive); and Dow Corning (®) 93-500 (Silicone encapsulant) were investigated. As extraction of bioburden from polymerized (solid) materials did not prove feasible, a method was devised to extract contaminants from uncured polymer precursors by dilution in organic solvents. Cultivation-dependent analyses showed less than 0.1-2.5 colony forming units (cfu) per cm³ polymer, whereas quantitative PCR with extracted DNA indicated considerably higher values, despite low DNA extraction efficiency. Results obtained by this method reflected the most conservative proxy for encapsulated bioburden. To observe the effect of physical and chemical stress occurring during polymerization on the viability of encapsulated contaminants, Bacillus safensis spores were embedded close to the surface in cured polymer, which facilitated access for different analytical techniques. Staining by AlexaFluor succinimidyl ester 488 (AF488), propidium monoazide (PMA), CTC (5-cyano-2,3-diotolyl tetrazolium chloride) and subsequent confocal laser scanning microscopy (CLSM) demonstrated that embedded spores retained integrity, germination and cultivation ability even after polymerization of the adhesive Scotch-Weld™ 2216 B/A.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

Energy Technology Data Exchange (ETDEWEB)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca, E-mail: f.iacopi@griffith.edu.au [Environmental Futures Research Institute, Griffith University, Nathan 4111 (Australia); Wood, Barry [Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia 4072 (Australia)

2016-05-02

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm{sup −2} with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

International Nuclear Information System (INIS)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca; Wood, Barry

2016-01-01

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm"−"2 with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

Stability of Polymer Ultrathin Films (Top-Down Approach.

Science.gov (United States)

Bal, Jayanta Kumar; Beuvier, Thomas; Unni, Aparna Beena; Chavez Panduro, Elvia Anabela; Vignaud, Guillaume; Delorme, Nicolas; Chebil, Mohamed Souheib; Grohens, Yves; Gibaud, Alain

2015-08-25

In polymer physics, the dewetting of spin-coated polystyrene ultrathin films on silicon remains mysterious. By adopting a simple top-down method based on good solvent rinsing, we are able to prepare flat polystyrene films with a controlled thickness ranging from 1.3 to 7.0 nm. Their stability was scrutinized after a classical annealing procedure above the glass transition temperature. Films were found to be stable on oxide-free silicon irrespective of film thickness, while they were unstable (2.9 nm) on 2 nm oxide-covered silicon substrates. The Lifshitz-van der Waals intermolecular theory that predicts the domains of stability as a function of the film thickness and of the substrate nature is now fully reconciled with our experimental observations. We surmise that this reconciliation is due to the good solvent rinsing procedure that removes the residual stress and/or the density variation of the polystyrene films inhibiting thermodynamically the dewetting on oxide-free silicon.

Adsorption of copolymers at polymer/air and polymer/solid interfaces

Science.gov (United States)

Oslanec, Robert

Using mainly low-energy forward recoil spectrometry (LE-FRES) and neutron reflectivity (NR), copolymer behavior at polymer/air and polymer/solid interfaces is investigated. For a miscible blend of poly(styrene-ran-acrylonitrile) copolymers, the volume fraction profile of the copolymer with lower acrylonitrile content is flat near the surface in contrast to mean field predictions. Including copolymer polydispersity into a self consistent mean field (SCMF) model does not account for this profile shape. LE-FRES and NR is also used to study poly(deuterated styrene-block-methyl-methacrylate) (dPS-b-PMMA) adsorption from a polymer matrix to a silicon oxide substrate. The interfacial excess, zsp*, layer thickness, L, and layer-matrix width, w, depend strongly on the number of matrix segments, P, for P 2N, the matrix chains are repelled from the adsorbed layer and the layer characteristics become independent of P. An SCMF model of block copolymer adsorption is developed. SCMF predictions are in qualitative agreement with the experimental behavior of zsp*, L, and w as a function of P. Using this model, the interaction energy of the MMA block with the oxide substrate is found to be -8ksb{B}T. In a subsequent experiment, the matrix/dPS interaction is made increasingly unfavorable by increasing the 4-bromostyrene mole fraction, x, in a poly(styrene-ran-4-bromostyrene) (PBrsbxS) matrix. Whereas experiments show that zsp* slightly decreases as x increases, the SCMF model predicts that zsp* should increase as the matrix becomes more unfavorable. Upon including a small matrix attraction for the substrate, the SCMF model shows that zsp* decreases with x because of competition between PBrsbxS and dPS-b-PMMA for adsorbing sites. In thin film dewetting experiments on silicon oxide, the addition of dPS-b-PMMA to PS coatings acts to slow hole growth and prevent holes from impinging. Dewetting studies show that longer dPS-b-PMMA chains are more effective stabilizing agents than shorter

Improved hemocompatibility of silicone rubber extracorporeal tubing via solvent swelling-impregnation of S-nitroso-N-acetylpenicillamine (SNAP) and evaluation in rabbit thrombogenicity model.

Science.gov (United States)

Brisbois, Elizabeth J; Major, Terry C; Goudie, Marcus J; Bartlett, Robert H; Meyerhoff, Mark E; Handa, Hitesh

2016-06-01

Blood-contacting devices, including extracorporeal circulation (ECC) circuits, can suffer from complications due to platelet activation and thrombus formation. Development of nitric oxide (NO) releasing polymers is one method to improve hemocompatibility, taking advantage of the ability of low levels of NO to prevent platelet activation/adhesion. In this study a novel solvent swelling method is used to load the walls of silicone rubber tubing with the NO donor S-nitroso-N-acetylpenicillamine (SNAP). This SNAP-silicone rubber tubing exhibits an NO flux of ca. 1×10(-10)molcm(-2)min(-1), which mimics the range of NO release from the normal endothelium, which is stable for at least 4h. Images of the tubing before and after swelling, obtained via scanning electron microscopy, demonstrate that this swelling method has little effect on the surface properties of the tubing. The SNAP-loaded silicone rubber and silicone rubber control tubing are used to fabricate ECC circuits that are evaluated in a rabbit model of thrombogenicity. After 4h of blood flow, the SNAP-loaded silicone rubber circuits were able to preserve the blood platelet count at 64% of baseline (vs. 12% for silicone rubber control). A 67% reduction in the degree of thrombus formation within the thrombogenicity chamber was also observed. This study demonstrates the ability to improve the hemocompatibility of existing/commercial silicone rubber tubing via a simple solvent swelling-impregnation technique, which may also be applicable to other silicone-based blood-contacting devices. Localized nitric oxide (NO) release can be achieved from biomedical grade polymers doped with S-nitroso-N-acetylpenicillamine (SNAP). Despite the promising in vitro and in vivo biocompatibility results reported for these NO releasing polymers, many of these materials may face challenges in being translated to clinical applications, especially in the areas of polymer processing and manufacturing. In this study, we report a solvent

Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

DEFF Research Database (Denmark)

Pu, Minhao; Liu, Liu; Ou, Haiyan

2010-01-01

An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....

Fundamental radiation effect on polymers energy transfer from radiation to polymer

International Nuclear Information System (INIS)

Seguchi, T.

2007-01-01

Polymer modification as cross-link, chain scission, and graft-polymerization by radiation is initiated by the quantum energy transferred from radiation to polymers. The active species for chemical reactions are produced through ionization or activation of polymer molecules for any radiation source. The energy transfer occurs mainly by ionic interaction between radiation and polymer molecule, and the contribution from the collision interaction is miner. The radiation of electromagnetic wave as X-ray or γ-ray generates the energetic electron which induces ionic interaction with polymer molecule. The energy loss profile along the penetration to polymer material is much different among the radiation sources of EB, γ-ray, and ion beams in the macroscopic mechanism. In this article, the behavior of single event, that is, the event induced by one electron, γ-ray, ion, and neutron is described by the macroscopic mechanism and by the microscopic mechanism. (authors)

Production of technical silicon and silicon carbide from rice-husk

Directory of Open Access Journals (Sweden)

A. Z. Issagulov

2014-10-01

Full Text Available In the article there are studied physical and chemical properties of silicon-carbonic raw material – rice-husk, thermophysical characteristics of the process of rice-husk pyrolysis in nonreactive and oxidizing environment; structure and phase composition of products of the rice-husk pyrolysis in interval of temperatures 150 – 850 °С and high temperature pyrolysis in interval of temperatures 900 – 1 500 °С. There are defined the silicon-carbon production conditions, which meet the requirements applicable to charging materials at production of technical silicon and silicon carbide.

Polymer and polymer-hybrid nanoparticles from synthesis to biomedical applications

CERN Document Server

Rangelov, Stanislav

2013-01-01

Polymeric and hybrid nanoparticles have received increased scientific interest in terms of basic research as well as commercial applications, promising a variety of uses for nanostructures in fields including bionanotechnology and medicine. Condensing the relevant research into a comprehensive reference, Polymer and Polymer-Hybrid Nanoparticles: From Synthesis to Biomedical Applications covers an array of topics from synthetic procedures and macromolecular design to possible biomedical applications of nanoparticles and materials based on original and unique polymers. The book presents a well-r

Optics Communications: Special issue on Polymer Photonics and Its Applications

Science.gov (United States)

Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing

2016-03-01

In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.

Single-chain-in-mean-field simulations of weak polyelectrolyte brushes

Science.gov (United States)

Léonforte, F.; Welling, U.; Müller, M.

2016-12-01

Structural properties of brushes which are composed of weak acidic and basic polyelectrolytes are studied in the framework of a particle-based approach that implicitly accounts for the solvent quality. Using a semi-grandcanonical partition function in the framework of the Single-Chain-in-Mean-Field (SCMF) algorithm, the weak polyelectrolyte is conceived as a supramolecular mixture of polymers in different dissociation states, which are explicitly treated in the partition function and sampled by the SCMF procedure. One obtains a local expression for the equilibrium acid-base reaction responsible for the regulation of the charged groups that is also incorporated to the SCMF sampling. Coupled to a simultaneous treatment of the electrostatics, the approach is shown to capture the main features of weak polyelectrolyte brushes as a function of the bulk pH in the solution, the salt concentration, and the grafting density. Results are compared to experimental and theoretical works from the literature using coarse-grained representations of poly(acrylic acid) (PAA) and poly(2-vinyl pyridine) (P2VP) polymer-based brushes. As the Born self-energy of ions can be straightforwardly included in the numerical approach, we also study its effect on the local charge regulation mechanism of the brush. We find that its effect becomes significant when the brush is dense and exposed to high salt concentrations. The numerical methodology is then applied (1) to the study of the kinetics of collapse/swelling of a P2VP brush and (2) to the ability of an applied voltage to induce collapse/swelling of a PAA brush in a pH range close to the pKa value of the polymer.

Scanning probe microscopy for the analysis of composite Ti/hydrocarbon plasma polymer thin films

Science.gov (United States)

Choukourov, A.; Grinevich, A.; Slavinska, D.; Biederman, H.; Saito, N.; Takai, O.

2008-03-01

Composite Ti/hydrocarbon plasma polymer films with different Ti concentration were deposited on silicon by dc magnetron sputtering of titanium in an atmosphere of argon and hexane. As measured by Kelvin force microscopy and visco-elastic atomic force microscopy, respectively, surface potential and hardness increase with increasing Ti content. Adhesion force to silicon and to fibrinogen molecules was stronger for the Ti-rich films as evaluated from the AFM force-distance curves. Fibrinogen forms a very soft layer on these composites with part of the protein molecules embedded in the outermost region of the plasma polymer. An increase of the surface charge due to fibrinogen adsorption has been observed and attributed to positively charged αC domains of fibrinogen molecule.

"Silicon millefeuille": From a silicon wafer to multiple thin crystalline films in a single step

Science.gov (United States)

Hernández, David; Trifonov, Trifon; Garín, Moisés; Alcubilla, Ramon

2013-04-01

During the last years, many techniques have been developed to obtain thin crystalline films from commercial silicon ingots. Large market applications are foreseen in the photovoltaic field, where important cost reductions are predicted, and also in advanced microelectronics technologies as three-dimensional integration, system on foil, or silicon interposers [Dross et al., Prog. Photovoltaics 20, 770-784 (2012); R. Brendel, Thin Film Crystalline Silicon Solar Cells (Wiley-VCH, Weinheim, Germany 2003); J. N. Burghartz, Ultra-Thin Chip Technology and Applications (Springer Science + Business Media, NY, USA, 2010)]. Existing methods produce "one at a time" silicon layers, once one thin film is obtained, the complete process is repeated to obtain the next layer. Here, we describe a technology that, from a single crystalline silicon wafer, produces a large number of crystalline films with controlled thickness in a single technological step.

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

Science.gov (United States)

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

2017-09-01

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

Synthesis, characterization and functionalization of silicon nanoparticle based hybrid nanomaterials for photovoltaic and biological applications

Science.gov (United States)

Xu, Zejing

Silicon nanoparticles are attractive candidates for biological, photovoltaic and energy storage applications due to their size dependent optoelectronic properties. These include tunable light emission, high brightness, and stability against photo-bleaching relative to organic dyes (see Chapter 1). The preparation and characterization of silicon nanoparticle based hybrid nanomaterials and their relevance to photovoltaic and biological applications are described. The surface-passivated silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with various organic ligands. The surface structure and optical properties of the passivated silicon nanoparticles were systematically characterized. Fast approaches for purifying and at the same time size separating the silicon nanoparticles using a gravity GPC column were developed. The hydrodynamic diameter and size distribution of these size-separated silicon nanoparticles were determined using GPC and Diffusion Ordered NMR Spectroscopy (DOSY) as fast, reliable alternative approaches to TEM. Water soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water stable chloroalkyl or alkynyl terminated nanoparticles, respectively. Nanoparticles with the ω-chloroalkyl substituents were easily converted to ω-azidoalkyl groups through the reaction of the silicon nanoparticles with sodium azide in DMF. The azido terminated nanoparticles were then grafted with monoalkynyl-PEG polymers using a copper catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently

On-demand Antimicrobial Treatment with Antibiotic-Loaded Porous Silicon Capped with a pH-Responsive Dual Plasma Polymer Barrier.

Science.gov (United States)

Vasani, Roshan B; Szili, Endre J; Rajeev, Gayathri; Voelcker, Nicolas H

2017-07-04

Chronic wounds are a major socio-economic problem. Bacterial infections in such wounds are a major contributor to lack of wound healing. An early indicator of wound infection is an increase in pH of the wound fluid. Herein, we describe the development of a pH-responsive drug delivery device that can potentially be used for wound decontamination in situ and on-demand in response to an increase in the pH of the wound environment. The device is based on a porous silicon film that provides a reservoir for encapsulation of an antibiotic within the pores. Loaded porous silicon is capped with dual plasma polymer layers of poly(1,7-octadiene) and poly(acrylic acid), which provide a pH-responsive barrier for on-demand release of the antibiotic. We demonstrate that release of the antibiotic is inhibited in aqueous buffer at pH 5, whereas the drug is released in a sustainable manner at pH 8. Importantly, the released drug was bacteriostatic against the Pseudomonas aeruginosa wound pathogen. In the future, incorporation of the delivery device into wound dressings could potentially be utilized for non-invasive decontamination of wounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fiscal 1993 R and D project for industrial science and technology. Report on results in developing methane-fueled aircraft engine (R and D on silicon-based polymeric material); 1993 nendo methane nenryo kokukiyo engine kaihatsu seika hokokusho. Keisokei kobunshi zairyo no gijutsu kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-01

R and D was conducted on silicon-based polymeric materials for structural use, for the purpose of establishing fundamental technologies such as molecular design, synthesis, material forming and evaluation method concerning silicon-based polymers, with the fiscal 1993 results summarized. In the studies of synthesis technologies of silicon-based polymeric materials having a sea-island structure, a series of polymers with an Si-C main chain structure were prepared by ring-opening polymerization of the cyclic monomers. In the studies of interpenetrating polymer network (IPN) structure forming technologies, polycarbosilanes with superior thermal stability and solvent solubility were synthesized through structural control based on molecular design. In the studies of composite structural materials between organic metallic complex and silicon-based high polymer, the compounding was carried out by introducing or blending organic metallic complex into the main chain of silicon polymer, with evaluation made on the heat resistance. The studies of silicon polymer structural materials having a ring structure were conducted on high heat resistant polymers that were obtained by dehydrocoupling polymerization with magnesia as a catalyst. (NEDO)

Inorganic Glue Enabling High Performance of Silicon Particles as Lithium Ion Battery Anode

KAUST Repository

Cui, Li-Feng

2011-01-01

Silicon, as an alloy-type anode material, has recently attracted lots of attention because of its highest known Li+ storage capacity (4200 mAh/g). But lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Silicon nanostructures such as nanowires and nanotubes can overcome the pulverization problem, however these nano-engineered silicon anodes usually involve very expensive processes and have difficulty being applied in commercial lithium ion batteries. In this study, we report a novel method using amorphous silicon as inorganic glue replacing conventional polymer binder. This inorganic glue method can solve the loss of contact issue in conventional silicon particle anode and enables successful cycling of various sizes of silicon particles, both nano-particles and micron particles. With a limited capacity of 800 mAh/g, relatively large silicon micron-particles can be stably cycled over 200 cycles. The very cheap production of these silicon particle anodes makes our method promising and competitive in lithium ion battery industry. © 2011 The Electrochemical Society.

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa

2013-05-30

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto; Sevilla, Galo T.

2013-01-01

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Synthesis of silicon nanocomposite for printable photovoltaic devices on flexible substrate

Science.gov (United States)

Odo, E. A.; Faremi, A. A.

2017-06-01

Renewed interest has been established in the preparation of silicon nanoparticles for electronic device applications. In this work, we report on the production of silicon powders using a simple ball mill and of silicon nanocomposite ink for screen-printable photovoltaic device on a flexible substrate. Bulk single crystalline silicon was milled for 25 h in the ball mill. The structural properties of the produced silicon nanoparticles were investigated using X-ray diffraction (XRD) and transmission electron microscopy. The results show that the particles remained highly crystalline, though transformed from their original single crystalline state to polycrystalline. The elemental composition using energy dispersive X-ray florescence spectroscopy (EDXRF) revealed that contamination from iron (Fe) and chromium (Cr) of the milling media and oxygen from the atmosphere were insignificant. The size distribution of the nanoparticles follows a lognormal pattern that ranges from 60 nm to about 1.2 μm and a mean particle size of about 103 nm. Electrical characterization of screen-printed PN structures of the nanocomposite formed by embedding the powder into a suitable water-soluble polymer on Kapton sheet reveals an enhanced photocurrent transport resulting from photo-induced carrier generation in the depletion region with energy greater that the Schottky barrier height at the metal-composite interface.

Hole Injection at the Silicon/Aqueous Electrolyte Interface: A Possible Mechanism for Chemiluminescence from Porous Silicon

NARCIS (Netherlands)

Kooij, Ernst S.; Butter, K.; Kelly, J.J.

1998-01-01

The reduction mechanism of oxidizing agents at silicon and porous silicon electrodes has been investigated in relation to light emission from the porous semiconductor. Oxidizing agents with a positive redox potential are shown to inject holes into HF-pretreated silicon. However, as the degree of

Osmotic load from glucose polymers.

Science.gov (United States)

Koo, W W; Poh, D; Leong, M; Tam, Y K; Succop, P; Checkland, E G

1991-01-01

Glucose polymer is a carbohydrate source with variable chain lengths of glucose units which may result in variable osmolality. The osmolality of two commercial glucose polymers was measured in reconstituted powder infant formulas, and the change in osmolality of infant milk formulas at the same increases in energy density (67 kcal/dL to 81 and 97 kcal/dL) from the use of additional milk powder or glucose polymers was compared. All samples were prepared from powders (to nearest 0.1 mg), and osmolality was measured by freezing point depression. For both glucose polymers the within-batch variability of the measured osmolality was less than 3.5%, and between-batch variability of the measured osmolality was less than 9.6%. The measured osmolality varies linearly with energy density (p less than 0.001) and was highest in infant formula reconstituted from milk powder alone. However, there exist significant differences in the measured osmolality between different glucose polymer preparations. At high energy densities (greater than or equal to 97 kcal/dL), infant milk formulas prepared with milk powder alone or with the addition of certain glucose polymer preparation may have high osmolality (greater than or equal to 450 mosm/kg) and theoretically predispose the infant to complications of hyperosmotic feeds.

Calibration of silicone rubber rods as passive samplers for pesticides at two different flow velocities: Modeling of sampling rates under water boundary layer and polymer control.

Science.gov (United States)

Martin, Alexis; Margoum, Christelle; Jolivet, Antoine; Assoumani, Azziz; El Moujahid, Bachir; Randon, Jérôme; Coquery, Marina

2018-04-01

There is a need to determine time-weighted average concentrations of polar contaminants such as pesticides by passive sampling in environmental waters. Calibration data for silicone rubber-based passive samplers are lacking for this class of compounds. The calibration data, sampling rate (R s ), and partition coefficient between silicone rubber and water (K sw ) were precisely determined for 23 pesticides and 13 candidate performance reference compounds (PRCs) in a laboratory calibration system over 14 d for 2 water flow velocities, 5 and 20 cm s -1 . The results showed that an in situ exposure duration of 7 d left a silicone rubber rod passive sampler configuration in the linear or curvilinear uptake period for 19 of the pesticides studied. A change in the transport mechanism from polymer control to water boundary layer control was observed for pesticides with a log K sw of approximately 3.3. The PRC candidates were not fully relevant to correct the impact of water flow velocity on R s . We therefore propose an alternative method based on an overall resistance to mass transfer model to adjust R s from laboratory experiments to in situ hydrodynamic conditions. We estimated diffusion coefficients (D s ) and thickness of water boundary layer (δ w ) as adjustable model parameters. Log D s values ranged from -12.13 to -10.07 m 2  s -1 . The estimated δ w value showed a power function correlation with water flow velocity. Environ Toxicol Chem 2018;37:1208-1218. © 2017 SETAC. © 2017 SETAC.

Electroluminescence from porous silicon due to electron injection from solution

NARCIS (Netherlands)

Kooij, Ernst S.; Despo, R.W.; Kelly, J.J.

1995-01-01

We report on the electroluminescence from p‐type porous silicon due to minority carrier injection from an electrolyte solution. The MV+• radical cation formed in the reduction of divalent methylviologen is able to inject electrons into the conduction band of crystalline and porous silicon. The

UVC fluencies for preventative treatment of Pseudomonas aeruginosa contaminated polymer tubes

DEFF Research Database (Denmark)

Bak, Jimmy; Ladefoged, Søren D; Begovic, Tanja

2010-01-01

Exposing Pseudomonas aeruginosa biofilm grown on the inner surface of Teflon and silicone tubes to UVC light (265 nm) from light emitting diodes (LED) has previously been shown to substantially reduce biofilm growth. Smaller UVC fluencies were required to disinfect Teflon tubes compared to silicone...... tubes. Light propagation enhancement in tubes can be obtained if the refractive index of the intra-luminal saline solution is higher than that of the polymer. This condition is achieved by using Teflon tubes with a low refractive index (1.34) instead of the polymers with a high refractive index (1...... is demonstrated to be a preventative disinfection treatment on tubes made of Teflon, which enhances the UVC light propagation, and on tubes made of a softer material, ethylene vinyl acetate (EVA), which is suitable for catheters but much less suitable for UVC light propagation. Simulating an aseptic breach (~10...

Polymer dynamics from synthetic polymers to proteins

Indian Academy of Sciences (India)

Abstract. Starting from the standard model of polymer motion – the Rouse model – .... reptation and the escape processes (creep motion) from the tube. .... scattering curves from an arrangement of small mesoscopic spheres also allows a.

Characterization of nanostructured CuO-porous silicon matrixformed on copper coated silicon substrate via electrochemical etching

International Nuclear Information System (INIS)

Naddaf, M.; Mrad, O.; Al-Zier, A.

2015-01-01

A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO-PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO-PS matrix exhibits an additional weak (blue) PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO-PS matrix.(author)

Inorganic polymers and materials. Final report

Energy Technology Data Exchange (ETDEWEB)

Sneddon, Larry G.

2001-01-01

This DOE-sponsored project was focused on the design, synthesis, characterization, and applications of new types of boron and silicon polymers with a goal of attaining processable precursors to advanced ceramic materials of technological importance. This work demonstrated a viable design strategy for the systematic formation of polymeric precursors to ceramics based on the controlled functionalization of preformed polymers with pendant groups of suitable compositions and crosslinking properties. Both the new dipentylamine-polyborazylene and pinacolborane-hydridopolysilazane polymers, unlike the parent polyborazylene and other polyborosilazanes, are stable as melts and can be easily spun into polymer fibers. Subsequent pyrolyses of these polymer fibers then provide excellent routes to BN and SiNCB ceramic fibers. The ease of synthesis of both polymer systems suggests new hybrid polymers with a range of substituents appended to polyborazylene or polysilazane backbones, as well as other types of preceramic polymers, should now be readily achieved, thereby allowing even greater control over polymer and ceramic properties. This control should now enable the systematic tailoring of the polymers and derived ceramics for use in different technological applications. Other major recent achievements include the development of new types of metal-catalyzed methods needed for the polymerization and modification of inorganic monomers and polymers, and the modification studies of polyvinylsiloxane and related polymers with substituents that enable the formation of single source precursors to high-strength, sintered SiC ceramics.

From polymers to quantum gravity: Triple-scaling in rectangular random matrix models

International Nuclear Information System (INIS)

Myers, R.C.; Periwal, V.

1993-01-01

Rectangular NxM matrix models can be solved in several qualitatively distinct large-N limits, since two independent parameters govern the size of the matrix. Regarded as models of random surfaces, these matrix models interpolate between branched polymer behaviour and two-dimensional quantum gravity. We solve such models in a 'triple-scaling' regime in this paper, with N and M becoming large independently. A correspondence between phase transitions and singularities of mappings from R 2 to R 2 is indicated. At different critical points, the scaling behaviour is determined by (i) two decoupled ordinary differential equations; (ii) an ordinary differential equation and a finite-difference equation; or (iii) two coupled partial differential equations. The Painleve II equation arises (in conjunction with a difference equation) at a point associated with branched polymers. For critical points described by partial differential equations, there are dual weak-coupling/strong-coupling expansions. It is conjectured that the new physics is related to microscopic topology fluctuations. (orig.)

Experimental investigation of the factors influencing the polymer-polymer bond strength during two component injection moulding

DEFF Research Database (Denmark)

Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

2007-01-01

Two component injection moulding is a commercially important manufacturing process and a key technology for Moulded Interconnect Devices (MIDs). Many fascinating applications of two component or multi component polymer parts are restricted due to the weak interfacial adhesion of the polymers...... effectively control the adhesion between two polymers. The effects of environmental conditions on the bond strength after moulding are also investigated. The material selections and environmental conditions were chosen based on the suitability of MID production, but the results and discussion presented....... A thorough understanding of the factors that influence the bond strength of polymers is necessary for multi component polymer processing. This paper investigates the effects of the process and material parameters on the bond strength of two component polymer parts and identifies the factors which can...

Experimental investigation of the factors influencing the polymer-polymer bond strength during two-component injection moulding

DEFF Research Database (Denmark)

Islam, Aminul; Hansen, Hans Nørgaard; Bondo, Martin

2010-01-01

Two-component injection moulding is a commercially important manufacturing process and a key technology for combining different material properties in a single plastic product. It is also one of most industrially adaptive process chain for manufacturing so-called moulded interconnect devices (MIDs......). Many fascinating applications of two-component or multi-component polymer parts are restricted due to the weak interfacial adhesion of the polymers. A thorough understanding of the factors that influence the bond strength of polymers is necessary for multi-component polymer processing. This paper...... investigates the effects of the process conditions and geometrical factors on the bond strength of two-component polymer parts and identifies the factors which can effectively control the adhesion between two polymers. The effects of environmental conditions on the bond strength are also investigated...

Porous silicon technology for integrated microsystems

Science.gov (United States)

Wallner, Jin Zheng

With the development of micro systems, there is an increasing demand for integrable porous materials. In addition to those conventional applications, such as filtration, wicking, and insulating, many new micro devices, including micro reactors, sensors, actuators, and optical components, can benefit from porous materials. Conventional porous materials, such as ceramics and polymers, however, cannot meet the challenges posed by micro systems, due to their incompatibility with standard micro-fabrication processes. In an effort to produce porous materials that can be used in micro systems, porous silicon (PS) generated by anodization of single crystalline silicon has been investigated. In this work, the PS formation process has been extensively studied and characterized as a function of substrate type, crystal orientation, doping concentration, current density and surfactant concentration and type. Anodization conditions have been optimized for producing very thick porous silicon layers with uniform pore size, and for obtaining ideal pore morphologies. Three different types of porous silicon materials: meso porous silicon, macro porous silicon with straight pores, and macro porous silicon with tortuous pores, have been successfully produced. Regular pore arrays with controllable pore size in the range of 2mum to 6mum have been demonstrated as well. Localized PS formation has been achieved by using oxide/nitride/polysilicon stack as masking materials, which can withstand anodization in hydrofluoric acid up to twenty hours. A special etching cell with electrolytic liquid backside contact along with two process flows has been developed to enable the fabrication of thick macro porous silicon membranes with though wafer pores. For device assembly, Si-Au and In-Au bonding technologies have been developed. Very low bonding temperature (˜200°C) and thick/soft bonding layers (˜6mum) have been achieved by In-Au bonding technology, which is able to compensate the potentially

Modification of Polymer Materials by Ion Bombardment: Case Studies

International Nuclear Information System (INIS)

Bielinski, D. M.; Jagielski, J.; Lipinski, P.; Pieczynska, D.; Ostaszewska, U.; Piatkowska, A.

2009-01-01

The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

Highly Sensitive Polymer-based Cantilever-sensors for DNA Detection

DEFF Research Database (Denmark)

Gomez, Montserrat; Nordström, Maria; Alvarez, M.

2005-01-01

We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel...... polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized...

Preparation and Characterization of Silicone Liquid Core/Polymer Shell Microcapsules via Internal Phase Separation

DEFF Research Database (Denmark)

Gonzalez, Lidia; Kostrzewska, Malgorzata; Ma, Baoguang

2014-01-01

Microcapsules with a silicone liquid core surrounded by a polymeric shell were synthesisedthrough the controlled phase separation. The dispersed silicone phase consisted of the shellpolymer PMMA, a good solvent for the PMMA (dichloromethane, DCM) and a poor solvent(methylhydrosiloxane dimethylsil......Microcapsules with a silicone liquid core surrounded by a polymeric shell were synthesisedthrough the controlled phase separation. The dispersed silicone phase consisted of the shellpolymer PMMA, a good solvent for the PMMA (dichloromethane, DCM) and a poor solvent...

Study of nano-metric silicon carbide powder sintering. Application to fibers processing

International Nuclear Information System (INIS)

Malinge, A.

2011-01-01

Silicon carbide ceramic matrix composites (SiCf/SiCm) are of interest for high temperature applications in aerospace or nuclear components for their relatively high thermal conductivity and low activation under neutron irradiation. While most of silicon carbide fibers are obtained through the pyrolysis of a poly-carbo-silane precursor, sintering of silicon carbide nano-powders seems to be a promising route to explore. For this reason, pressureless sintering of SiC has been studied. Following the identification of appropriate sintering aids for the densification, optimization of the microstructure has been achieved through (i) the analysis of the influence of operating parameters and (ii) the control of the SiC β a SiC α phase transition. Green fibers have been obtained by two different processes involving the extrusion of SiC powder dispersion in polymer solution or the coagulation of a water-soluble polymer containing ceramic particles. Sintering of these green fibers led to fibers of around fifty microns in diameter. (author) [fr

The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots

Science.gov (United States)

Yoo, Hana; Park, Soojin

2010-06-01

We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm × 5 cm.

The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots

Energy Technology Data Exchange (ETDEWEB)

Yoo, Hana; Park, Soojin, E-mail: spark@unist.ac.kr [Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology, Banyeon-ri 100, Ulsan 689-798 (Korea, Republic of)

2010-06-18

We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm x 5 cm.

Bioactive Wollastonite-Diopside Foams from Preceramic Polymers and Reactive Oxide Fillers

Directory of Open Access Journals (Sweden)

Laura Fiocco

2015-05-01

Full Text Available Wollastonite (CaSiO3 and diopside (CaMgSi2O6 silicate ceramics have been widely investigated as highly bioactive materials, suitable for bone tissue engineering applications. In the present paper, highly porous glass-ceramic foams, with both wollastonite and diopside as crystal phases, were developed from the thermal treatment of silicone polymers filled with CaO and MgO precursors, in the form of micro-sized particles. The foaming was due to water release, at low temperature, in the polymeric matrix before ceramic conversion, mainly operated by hydrated sodium phosphate, used as a secondary filler. This additive proved to be “multifunctional”, since it additionally favored the phase development, by the formation of a liquid phase upon firing, in turn promoting the ionic interdiffusion. The liquid phase was promoted also by the incorporation of powders of a glass crystallizing itself in wollastonite and diopside, with significant improvements in both structural integrity and crushing strength. The biological characterization of polymer-derived wollastonite-diopside foams, to assess the bioactivity of the samples, was performed by means of a cell culture test. The MTT assay and LDH activity tests gave positive results in terms of cell viability.

Characterization of nanostructured CuO-porous silicon matrix formed on copper-coated silicon substrate via electrochemical etching

Science.gov (United States)

Naddaf, M.; Mrad, O.; Al-zier, A.

2014-06-01

A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO-PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO-PS matrix exhibits an additional weak `blue' PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO-PS matrix.

Multifunctional Polymer Nanocomposites

Science.gov (United States)

Galaska, Alexandra Maria; Song, Haixiang; Guo, Zhanhu

With more awareness of energy conversion/storage and saving, different strategies have been developed to utilize the sustainable and renewable energy. Introducing nanoscale fillers can make inert polymer matrix possess unique properties to satisfy certain functions. For example, alumina nanoparticles have strengthened the weak thermosetting polymers. A combined mixture of carbon nanofibers and magnetite nanoparticles have made the inert epoxy sensitive for magnetic field for sensing applications. Introducing silica nanoparticles into conductive polymers such as polyaniline has enhanced the giant magnetoresistance behaviors. The introduced nanoparticles have made the transparent polymer have the electromagnetic interference (EMI) shielding function while reduce the density significantly. With the desired miniaturization, the materials combining different functionalities have become importantly interesting. In this talk, methodologies to prepare nanocomposites and their effects on the produced nanocomposites will be discussed. A variety of advanced polymer nanocomposites will be introduced. Unique properties including mechanical, electrical, magnetoresistance etc. and the applications for environmental remediation, energy storage/saving, fire retardancy, electromagnetic interference shielding, and electronic devices will be presented.

Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

International Nuclear Information System (INIS)

Luo, B.; Brandt, W. N.; Scott, A. E.; Alexander, D. M.; Gandhi, P.; Stern, D.; Teng, S. H.; Arévalo, P.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Ogle, P.; Puccetti, S.; Saez, C.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ eff ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

Mechanical and Electrical Ageing Effects on the Long-Term Stretching of Silicone Dielectric Elastomers with Soft Fillers

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Zakaria, Shamsul Bin; Yu, Liyun

2016-01-01

Dielectric elastomer materials for actuators need to be soft and stretchable while possessing high dielectric permittivity. Soft silicone elastomers can be obtained through the use of silicone oils, while enhanced permittivity can be obtained through the use of dipolar groups on the polymer backb...

Thin film silicon modules on plastic superstrates

NARCIS (Netherlands)

Rath, J.K.; Liu, Y; Borreman, A.; Hamers, E.A.G.; Schlatmann, R.; Jongerden, G.J.; Schropp, R.E.I.

2008-01-01

The aim of this research is to fabricate high efficiency a-Si/μc-Si tandem solar cell modules on flexible (polymer) superstrates using the Helianthos concept. As a first step we began by depositing the top cell which contains an amorphous silicon (a-Si:H) i-layer of 350 nm made by VHF PECVD at 50

Relationship Between Cell Compatibility and Elastic Modulus of Silicone Rubber/Organoclay Nanobiocomposites

Science.gov (United States)

Hosseini, Motahare Sadat; Tazzoli-Shadpour, Mohammad; Amjadi, Issa; Haghighipour, Nooshin; Shokrgozar, Mohammad Ali; Ghafourian Boroujerdnia, Mehri

2012-01-01

Background Substrates in medical science are hydrophilic polymers undergoing volume expansion when exposed to culture medium that influenced on cell attachment. Although crosslinking by chemical agents could reduce water uptake and promote mechanical properties, these networks would release crosslinking agents. In order to overcome this weakness, silicone rubber is used and reinforced by nanoclay. Objectives Attempts have been made to prepare nanocomposites based on medical grade HTV silicone rubber (SR) and organo-modified montmorillonite (OMMT) nanoclay with varying amounts of clay compositions. Materials and Methods Incorporation of nanocilica platelets into SR matrix was carried out via melt mixing process taking advantage of a Brabender internal mixer. The tensile elastic modulus of nanocomposites was measured by performing tensile tests on the samples. Produced polydimetylsiloxane (PDMS) composites with different flexibilities and crosslink densities were employed as substrates to investigate biocompatibility, cell compaction, and differential behaviors. Results The results presented here revealed successful nanocomposite formation with SR and OMMT, resulting in strong PDMS-based materials. The results showed that viability, proliferation, and spreading of cells are governed by elastic modulus and stiffness of samples. Furthermore, adipose derived stem cells (ADSCs) cultured on PDMS and corresponding nanocomposites could retain differentiation potential of osteocytes in response to soluble factors, indicating that inclusion of OMMT would not prevent osteogenic differentiation. Moreover, better spread out and proliferation of cells was observed in nanocomposite samples. Conclusions Considering cell behavior and mechanical properties of nanobiocomposites it could be concluded that silicone rubber substrate filled by nanoclay are a good choice for further experiments in tissue engineering and medical regeneration due to its cell compatibility and differentiation

Tungsten atomic layer deposition on polymers

Energy Technology Data Exchange (ETDEWEB)

Wilson, C.A. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); McCormick, J.A. [Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States); Cavanagh, A.S. [Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States); Goldstein, D.N. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Weimer, A.W. [Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States); George, S.M. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States)], E-mail: Steven.George@Colorado.Edu

2008-07-31

Tungsten (W) atomic layer deposition (ALD) was investigated on a variety of polymer films and polymer particles. These polymers included polyethylene, polyvinyl chloride, polystyrene, polycarbonate, polypropylene and polymethylmethacrylate. The W ALD was performed at 80 {sup o}C using WF{sub 6} and Si{sub 2}H{sub 6} as the gas phase reactants. W ALD on flat polymer films can eventually nucleate and grow after more than 60 AB cycles. X-ray photoelectron spectroscopy studies of W ALD on polystyrene after 50 AB cycles suggested that tungsten nanoclusters are present in the W ALD nucleation regime. The W ALD nucleation is greatly facilitated by a few cycles of Al{sub 2}O{sub 3} ALD. W ALD films were grown at 80 {sup o}C on spin-coated polymers on silicon wafers after 10 AB cycles of Al{sub 2}O{sub 3} ALD. The W ALD film was observed to grow linearly with a growth rate of 3.9 A per AB cycle on the polymer films treated with the Al{sub 2}O{sub 3} ALD seed layer. The W ALD films displayed an excellent, mirror-like optical reflectivity. The resistivity was 100-400 {mu}{omega} cm for W ALD films with thicknesses from 95-845 A. W ALD was also observed on polymer particles after W ALD in a rotary reactor. Without the Al{sub 2}O{sub 3} ALD seed layer, the nucleation of W ALD directly on the polymer particles at 80 {sup o}C required > 50 AB cycles. In contrast, the polymer particles treated with only 5 AB cycles of Al{sub 2}O{sub 3} ALD were observed to blacken after 25 AB cycles of W ALD. W ALD on polymers may have applications for flexible optical mirrors, electromagnetic interference shielding and gas diffusion barriers.

Photopatterning of heterostructured polymer Langmuir-Blodgett films

International Nuclear Information System (INIS)

Li Tiesheng; Mitsuishi, Masaya; Miyashita, Tokuji

2008-01-01

Heterostructured polymer Langmuir-Blodgett (LB) film prepared by using poly(N-dodecylacrylamide-co-t-butyl 4-vinylphenyl carbonate) (p(DDA-tBVPC53)) and poly(N-neopentyl methacrylamide-co-9-anthrylmethyl methacrylate) (p(nPMA-AMMA10)) polymer LB films which can act as photogenerator layers were investigated. Patterns with a resolution of 0.75 μm were obtained on heterostructured polymer LB films composed of 4 layers of p(nPMA-AMMA10) LB film (top layers) and 40 layers of p(DDA-tBVPC53) LB film (under layers) on a silicon wafer by deep UV irradiation followed by development with 1% tetramethylammonium hydroxide aqueous solution. The sensitivity of the heterostructured polymer LB films was improved without loss of the resolution compared with p(DDA-tBVPC53) LB film. The etch resistance of the heterostructured polymer LB films was sufficiently good to allow patterning of a copper film suitable for photomask fabrication

Approaches for Making High Performance Polymer Materials from Commodity Polymers

Institute of Scientific and Technical Information of China (English)

Xu Xi

2004-01-01

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

Synthesis and application of new polymer bound catalysts

Energy Technology Data Exchange (ETDEWEB)

Fetterly, Brandon Michael [Iowa State Univ., Ames, IA (United States)

2005-01-01

Nitric acid has been shown to be a weak acid in acetonitrile. It is conceivable that a nitrate salt of a weakly Lewis acidic cation could furnish a ''naked'' nitrate anion as a basic catalyst in a variety of reactions in non-aqueous solvents. Such a nitrate salt could also be bound to a polymeric support via the cation, thereby allowing for reclamation and recycling of the nitrate ion. This subject is dealt with in Chapter 2, wherein my contributions consisted of performing all the reactions with the polymer supported catalyst and carrying out the experiments necessary to shed light on the reaction mechanisms. Chapter 3 contains a description of the structure and catalytic properties of an azidoproazaphosphatrane. This compound is an air-stable versatile catalyst that has proven useful not only homogeneously, but also when bound to a solid support. The synthesis of a polymer bound proazaphosphatrane containing a trivalent phosphorus is presented in Chapter 4. Such a compound has been sought after by our group for a number of years. Not only does the synthesis I have accomplished for it allow for easier separation of proazaphosphatrane catalysts from reaction mixtures, but recycling of the base is made much simpler. Proazaphosphatranes are useful homogeneous catalysts that activate atoms in other reagents, thus enhancing their reactivity. The next chapters deal with two such reactions with aldehydes and ketones, namely silylcyanations with trialkylsilylcyanides (Chapters 5 and 6) and reductions with poly(methylhydrosiloxane), in Chapter 7. In Chapter 5, Zhigang Wang performed the initial optimization and scoping of the reaction, while repetitions of the scoping experiments for reproducibility, determination of diastereomeric ratios, and experiments aimed at elucidating aspects of the mechanism were performed by me. The proazaphosphatrane coordinates to the silicon atom in both cases, thereby allowing the aforementioned reactions to proceed under

Super soft silicone elastomers with high dielectric permittivity

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Hvilsted, Søren

2015-01-01

Dielectric elastomers (DEs) have many favourable properties. The obstacle of high driving voltages, however, limits the commercial viability of the technology at present. Driving voltage can be lowered by decreasing the Young’s modulus and increasing the dielectric permittivity of silicone...... elastomers. A decrease in Young’s modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE. New soft elastomer matrices with high dielectric permittivity and low Young’s modulus, with no loss of mechanical stability, were prepared by two different...... approaches using chloropropyl-functional silicone polymers. The first approach was based on synthesised chloropropyl-functional copolymers that were cross-linkable and thereby formed the basis of new silicone networks with high dielectric permittivity (e.g. a 43% increase). These networks were soft without...

Fiscal 1992 R and D project for next generation infrastructure technology. Report on results of R and D on silicon-based polymeric material; 1992 nendo keisokei kobunshi zairyo no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-03-01

R and D was conducted with the purpose of establishing fundamental technologies for molecular design, synthesis, material formation and evaluation method concerning silicon-based polymer. with the fiscal 1992 results summarized. In the studies on synthesis technology of electrically conductive silicon-based polymeric materials, silicon-based compounds were synthesized including in particular -Si-Si- bond and carbon multiple bond like -C-C-, with acquisition/analysis of material data started. In the studies on new silicon-based polymeric materials capable of circuit plotting, syntheses were performed for network polysilanes through the disproportionation reaction of alkoxydisilanes. In the studies on new silicon-based polymeric materials having a light emitting function, evaluation of oxidation-reduction potential and search for synthesizing conditions were performed for halosilanes and hydrosilanes. In the studies on silicon-based photoelectric conversion materials, molecular design progressed using a crystal orbital method. Furthermore, researches were implemented on such subjects as silicon-based polymeric materials having a sea-island structure, interpenetrating polymer network forming technologies, and composite structural materials composed of organic metallic complex and silicon-based polymers. (NEDO)

Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

Science.gov (United States)

Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

2017-03-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

Additive manufacturing of polymer-derived ceramics

Science.gov (United States)

Eckel, Zak C.; Zhou, Chaoyin; Martin, John H.; Jacobsen, Alan J.; Carter, William B.; Schaedler, Tobias A.

2016-01-01

The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

Recycling of silicon: from industrial waste to biocompatible nanoparticles for nanomedicine

Science.gov (United States)

Kozlov, N. K.; Natashina, U. A.; Tamarov, K. P.; Gongalsky, M. B.; Solovyev, V. V.; Kudryavtsev, A. A.; Sivakov, V.; Osminkina, L. A.

2017-09-01

The formation of photoluminescent porous silicon (PSi) nanoparticles (NPs) is usually based on an expensive semiconductor grade wafers technology. Here, we report a low-cost method of PSi NPs synthesis from the industrial silicon waste remained after the wafer production. The proposed method is based on metal-assisted wet-chemical etching (MACE) of the silicon surface of cm-sized metallurgical grade silicon stones which leads to a nanostructuring of the surface due to an anisotropic etching, with subsequent ultrasound fracturing in water. The obtained PSi NPs exhibit bright red room temperature photoluminescence (PL) and demonstrate similar microstructure and physical characteristics in comparison with the nanoparticles synthesized from semiconductor grade Si wafers. PSi NPs prepared from metallurgical grade silicon stones, similar to silicon NPs synthesized from high purity silicon wafer, show low toxicity to biological objects that open the possibility of using such type of NPs in nanomedicine.

Drug delivery's quest for polymers: Where are the frontiers?

Science.gov (United States)

Merkle, Hans P

2015-11-01

Since the legendary 1964 article of Folkman and Long entitled "The use of silicone rubber as a carrier for prolonged drug therapy" the role of polymers in controlled drug delivery has come a long way. Today it is evident that polymers play a crucial if not the prime role in this field. The latest boost owes to the interest in drug delivery for the purpose of tissue engineering in regenerative medicine. The focus of this commentary is on a selection of general and personal observations that are characteristic for the current state of polymer therapeutics and carriers. It briefly highlights selected examples for the long march of synthetic polymer-drug conjugates from bench to bedside, comments on the ambivalence of selected polymers as inert excipients versus biological response modifiers, and on the yet unsolved dilemma of cationic polymers for the delivery of nucleic acid therapeutics. Further subjects are the complex design of multifunctional polymeric carriers including recent concepts towards functional supramolecular polymers, as well as observations on stimuli-sensitive polymers and the currently ongoing trend towards natural and naturally-derived biopolymers. The final topic is the discovery and early development of a novel type of biodegradable polyesters for parenteral use. Altogether, it is not the basic and applied research in polymer therapeutics and carriers, but the translational process that is the key hurdle to proceed towards an authoritative approval of new polymer therapeutics and carriers. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication of combined-scale nano- and microfluidic polymer systems using a multilevel dry etching, electroplating and molding process

DEFF Research Database (Denmark)

Tanzi, Simone; Østergaard, Peter Friis; Matteucci, Marco

2012-01-01

Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions to fabric......Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions...

Silicon microring refractometric sensor for atmospheric CO(2) gas monitoring.

Science.gov (United States)

Mi, Guangcan; Horvath, Cameron; Aktary, Mirwais; Van, Vien

2016-01-25

We report a silicon photonic refractometric CO(2) gas sensor operating at room temperature and capable of detecting CO(2) gas at atmospheric concentrations. The sensor uses a novel functional material layer based on a guanidine polymer derivative, which is shown to exhibit reversible refractive index change upon absorption and release of CO(2) gas molecules, and does not require the presence of humidity to operate. By functionalizing a silicon microring resonator with a thin layer of the polymer, we could detect CO(2) gas concentrations in the 0-500ppm range with a sensitivity of 6 × 10(-9) RIU/ppm and a detection limit of 20ppm. The microring transducer provides a potential integrated solution in the development of low-cost and compact CO(2) sensors that can be deployed as part of a sensor network for accurate environmental monitoring of greenhouse gases.

Dielectric properties of DNA oligonucleotides on the surface of silicon nanostructures

Energy Technology Data Exchange (ETDEWEB)

Bagraev, N. T., E-mail: bagraev@mail.ioffe.ru [St. Petersburg Polytechnic University (Russian Federation); Chernev, A. L. [Russian Academy of Sciences, St. Petersburg Academic University—Nanotechnology Research and Education Center (Russian Federation); Klyachkin, L. E. [St. Petersburg Polytechnic University (Russian Federation); Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Emel’yanov, A. K.; Dubina, M. V. [Russian Academy of Sciences, St. Petersburg Academic University—Nanotechnology Research and Education Center (Russian Federation)

2016-10-15

Planar silicon nanostructures that are formed as a very narrow silicon quantum well confined by δ barriers heavily doped with boron are used to study the dielectric properties of DNA oligonucleotides deposited onto the surface of the nanostructures. The capacitance characteristics of the silicon nanostructures with oligonucleotides deposited onto their surface are determined by recording the local tunneling current–voltage characteristics by means of scanning tunneling microscopy. The results show the possibility of identifying the local dielectric properties of DNA oligonucleotide segments consisting of repeating G–C pairs. These properties apparently give grounds to correlate the segments with polymer molecules exhibiting the properties of multiferroics.

Use of hydroxypropylmethylcellulose 2% for removing adherent silicone oil from silicone intraocular lenses

OpenAIRE

Wong , S Chien; Ramkissoon , Yashin D; Lopez , Mauricio; Page , Kristopher; Parkin , Ivan P; Sullivan , Paul M

2009-01-01

Abstract Background / aims: To investigate the effect of hydroxypropylmethylcellulose (HPMC) on the physical interaction (contact angle) between silicone oil and a silicone intraocular lens (IOL). Methods: In vitro experiments were performed, to determine the effect of HPMC (0.5%, 1% or 2%), with or without an additional simple mechanical manoeuvre, on the contact angle of silicone oil at the surface of both silicone and acrylic (control) IOLs. A balanced salt solu...

Effects of Grafting Density on Block Polymer Self-Assembly: From Linear to Bottlebrush.

Science.gov (United States)

Lin, Tzu-Pin; Chang, Alice B; Luo, Shao-Xiong; Chen, Hsiang-Yun; Lee, Byeongdu; Grubbs, Robert H

2017-11-28

Grafting density is an important structural parameter that exerts significant influences over the physical properties of architecturally complex polymers. In this report, the physical consequences of varying the grafting density (z) were studied in the context of block polymer self-assembly. Well-defined block polymers spanning the linear, comb, and bottlebrush regimes (0 ≤ z ≤ 1) were prepared via grafting-through ring-opening-metathesis polymerization. ω-Norbornenyl poly(d,l-lactide) and polystyrene macromonomers were copolymerized with discrete comonomers in different feed ratios, enabling precise control over both the grafting density and molecular weight. Small-angle X-ray scattering experiments demonstrate that these graft block polymers self-assemble into long-range-ordered lamellar structures. For 17 series of block polymers with variable z, the scaling of the lamellar period with the total backbone degree of polymerization (d* ∼ N bb α ) was studied. The scaling exponent α monotonically decreases with decreasing z and exhibits an apparent transition at z ≈ 0.2, suggesting significant changes in the chain conformations. Comparison of two block polymer systems, one that is strongly segregated for all z (System I) and one that experiences weak segregation at low z (System II), indicates that the observed trends are primarily caused by the polymer architectures, not segregation effects. A model is proposed in which the characteristic ratio (C ∞ ), a proxy for the backbone stiffness, scales with N bb as a function of the grafting density: C ∞ ∼ N bb f(z) . The scaling behavior disclosed herein provides valuable insights into conformational changes with grafting density, thus introducing opportunities for block polymer and material design.

A review of piezoelectric polymers as functional materials for electromechanical transducers

International Nuclear Information System (INIS)

Ramadan, Khaled S; Evoy, S; Sameoto, D

2014-01-01

Polymer based MEMS and microfluidic devices have the advantages of mechanical flexibility, lower fabrication cost and faster processing over silicon based ones. Also, many polymer materials are considered biocompatible and can be used in biological applications. A valuable class of polymers for microfabricated devices is piezoelectric functional polymers. In addition to the normal advantages of polymers, piezoelectric polymers can be directly used as an active material in different transduction applications. This paper gives an overview of piezoelectric polymers based on their operating principle. This includes three main categories: bulk piezoelectric polymers, piezocomposites and voided charged polymers. State-of-the-art piezopolymers of each category are presented with a focus on fabrication techniques and material properties. A comparison between the different piezoelectric polymers and common inorganic piezoelectric materials (PZT, ZnO, AlN and PMN–PT) is also provided in terms of piezoelectric properties. The use of piezopolymers in different electromechanical devices is also presented. This includes tactile sensors, energy harvesters, acoustic transducers and inertial sensors. (topical review)

Direct covalent coupling of proteins to nanostructured plasma polymers: a route to tunable cell adhesion

International Nuclear Information System (INIS)

Melnichuk, Iurii; Choukourov, Andrei; Bilek, Marcela; Weiss, Anthony; Vandrovcová, Marta; Bačáková, Lucie; Hanuš, Jan; Kousal, Jaroslav; Shelemin, Artem; Solař, Pavel

2015-01-01

Highlights: • Flat and nanostructured interfaces were overcoated by hydrocarbon plasma polymer. • Linker-free covalent attachment of proteins to resultant surfaces was validated. • Ultra-thin hydrocarbon overcoat (<2 nm) secured prolonged effective binding. • Pre-adsorbed tropoelastin promoted proliferation of osteoblast-like MG-63 cells. • Nanostructured films were multi-affine and impeded cell adhesion. - Abstract: Flat and nanostructured thin films were fabricated by deposition of ultra-thin (<2 nm) layer of hydrocarbon plasma polymer over polished silicon and over a pattern of 8 nm-thick poly(ethylene) islands on silicon. Linker-free radical-based covalent binding of bovine serum albumin and tropoelastin was confirmed for both types of films. The binding capability of albumin was found to be stable over many days of ambient air storage time. Tropoelastin-mediated flat plasma polymers favored adhesion and proliferation of osteoblast-like MG-63 cells. Nanostructured plasma polymers were multi-affine and their hierarchical surface represented an additional barrier for cell attachment

Hazardous industrial gases identified using a novel polymer/MWNT composite resistance sensor array

International Nuclear Information System (INIS)

Yuana, C.L.; Chang, C.P.; Song, Y.

2011-01-01

Highlights: → In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. → This work developed polymer-functionalized MWNT sensor plat forms for the detection of vapors from chemical agents at different temperatures. → Applied PCA to determine the performance of as-fabricated films for exposure to three chemical agents. - Abstract: Hazardous industrial chemical gases pose a significant threat to the environment and human life. Therefore, there is an urgent need to develop a reliable sensor for identifying these hazardous gases. In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. Conductive carbon nanotubes were then mixed with six different polymers with different chemical adsorption properties to produce a composite thin film for the fabrication of a chemical sensor array. This array was then utilized to identify three hazardous gases at different temperatures. Experimental results for six polymers for chemical gases, such as tetrahydrofuran (THF), chloroform (CHCl 3 ) and methanol (MeOH) at different temperatures, indicate that the variation in sensitivity resistance increased when the sensing temperature increased. The poly(ethylene adipate)/MWNT sensing film had high sensitivity, excellent selectivity, and good reproducibility in detecting all chemical agent vapors. Additionally, this study utilized a bar chart and statistical methods in principal component analysis to identify gases with the polymer/MWNT sensor.

Functional patterns obtained by nanoimprinting lithography and subsequent growth of polymer brushes

International Nuclear Information System (INIS)

Genua, A; AlduncIn, J A; Pomposo, J A; Grande, H; Kehagias, N; Reboud, V; Sotomayor, C; Mondragon, I; Mecerreyes, D

2007-01-01

In this work the growth of polymer brushes was combined with nanoimprint lithography (NIL) in order to obtain new functional nanopatterns. First, a functional thermoplastic methacrylic copolymer poly(methyl methacrylate-co-2-bromoisobutyryl-oxy-ethyl methacrylate) was synthesized. This copolymer was successfully patterned by NIL using a silicon stamp at 160 deg. C and 60 bar. Next, hydrophilic polymer brushes based on poly(3-sulfopropylmethacrylate) and hydrophobic polymer brushes based on a poly(fluorinated methacrylate) were grown on the imprinted surfaces. The surface properties of the patterned polymer were accordingly modified and, as a consequence, the water contact angle was modified from 80.3 deg. to 32.5 deg. in the case of the hydrophilic brushes and to 118.1 deg. in the case of the hydrophobic brushes. As an application we demonstrated the use of hydrophobic polymer brushes in order to modify the surface of polymeric stamps for NIL with self-demoulding properties

White-light emission from porous-silicon-aluminium Schottky junctions

International Nuclear Information System (INIS)

Masini, G.; La Monica, S.; Maiello, G.

1996-01-01

Porous-silicon-based white-light-emitting devices are presented. The fabrication process on different substrates is described. The peculiarities of technological steps for device fabrication (porous-silicon formation and aluminium treatment) are underlined. Doping profile of the porous layer, current-voltage characteristics, time response, lifetime tests and electroluminescence emission spectrum of the device are presented. A model for electrical behaviour of Al/porous silicon Schottky junction is presented. Electroluminescence spectrum of the presented devices showed strong similarities with white emission from crystalline silicon junctions in the breakdown region

Nature's Mechanisms for Tough, Self-healing Polymers and Polymer Adhesives

Science.gov (United States)

Hansma, Paul

2007-03-01

Spider silk^2 and the natural polymer adhesives in abalone shells^3 and bone^4,5 can give us insights into nature's mechanisms for tough, self-healing polymers and polymer adhesives. The natural polymer adhesives in biomaterials have been optimized by evolution. An optimized polymer adhesive has five characteristics. 1) It holds together the strong elements of the composite. 2) It yields just before the strong elements would otherwise break. 3) It dissipates large amounts of energy as it yields. 4) It self heals after it yields. 5) It takes just a few percent by weight. Both natural polymer adhesives and silk rely on sacrificial bonds and hidden length for toughness and self-healing.^6 A relatively large energy, of order 100eV, is required to stretch a polymer molecule after a weak bond, a sacrificial bond, breaks and liberates hidden length, which was previously hidden, typically in a loop or folded domain, from whatever was stretching the polymer. The bond is called sacrificial if it breaks at forces well below the forces that could otherwise break the polymer backbone, typically greater than 1nN. In many biological cases, the breaking of sacrificial bonds has been found to be reversible, thereby also providing a ``self-healing'' property to the material.^2-4 Individual polymer adhesive molecules based on sacrificial bonds and hidden length can supply forces of order 300pN over distances of 100s of nanometers. Model calculations show that a few percent by weight of adhesives based on these principles could be optimized adhesives for high performance composite materials including nanotube and graphene sheet composites. ^2N. Becker, E. Oroudjev, S. Mutz et al., Nature Materials 2 (4), 278 (2003). ^3B. L. Smith, T. E. Schaffer, M. Viani et al., Nature 399 (6738), 761 (1999). ^4J. B. Thompson, J. H. Kindt, B. Drake et al., Nature 414 (6865), 773 (2001). ^5G. E. Fantner, T. Hassenkam, J. H. Kindt et al., Nature Materials 4, 612 (2005). ^6G. E. Fantner, E. Oroudjev, G

76 FR 78313 - Crystalline Silicon Photovoltaic Cells and Modules From China

Science.gov (United States)

2011-12-16

...)] Crystalline Silicon Photovoltaic Cells and Modules From China Determinations On the basis of the record \\1... injured by reason of imports from China of crystalline silicon photovoltaic cells and modules, provided... imports of crystalline silicon photovoltaic cells and modules from China. Accordingly, effective October...

Silicon spintronics: Progress and challenges

Energy Technology Data Exchange (ETDEWEB)

Sverdlov, Viktor; Selberherr, Siegfried, E-mail: Selberherr@TUWien.ac.at

2015-07-14

Electron spin attracts much attention as an alternative to the electron charge degree of freedom for low-power reprogrammable logic and non-volatile memory applications. Silicon appears to be the perfect material for spin-driven applications. Recent progress and challenges regarding spin-based devices are reviewed. An order of magnitude enhancement of the electron spin lifetime in silicon thin films by shear strain is predicted and its impact on spin transport in SpinFETs is discussed. A relatively weak coupling between spin and effective electric field in silicon allows magnetoresistance modulation at room temperature, however, for long channel lengths. Due to tunneling magnetoresistance and spin transfer torque effects, a much stronger coupling between the spin (magnetization) orientation and charge current is achieved in magnetic tunnel junctions. Magnetic random access memory (MRAM) built on magnetic tunnel junctions is CMOS compatible and possesses all properties needed for future universal memory. Designs of spin-based non-volatile MRAM cells are presented. By means of micromagnetic simulations it is demonstrated that a substantial reduction of the switching time can be achieved. Finally, it is shown that any two arbitrary memory cells from an MRAM array can be used to perform a logic operation. Thus, an intrinsic non-volatile logic-in-memory architecture can be realized.

Silicon spintronics: Progress and challenges

International Nuclear Information System (INIS)

Sverdlov, Viktor; Selberherr, Siegfried

2015-01-01

Electron spin attracts much attention as an alternative to the electron charge degree of freedom for low-power reprogrammable logic and non-volatile memory applications. Silicon appears to be the perfect material for spin-driven applications. Recent progress and challenges regarding spin-based devices are reviewed. An order of magnitude enhancement of the electron spin lifetime in silicon thin films by shear strain is predicted and its impact on spin transport in SpinFETs is discussed. A relatively weak coupling between spin and effective electric field in silicon allows magnetoresistance modulation at room temperature, however, for long channel lengths. Due to tunneling magnetoresistance and spin transfer torque effects, a much stronger coupling between the spin (magnetization) orientation and charge current is achieved in magnetic tunnel junctions. Magnetic random access memory (MRAM) built on magnetic tunnel junctions is CMOS compatible and possesses all properties needed for future universal memory. Designs of spin-based non-volatile MRAM cells are presented. By means of micromagnetic simulations it is demonstrated that a substantial reduction of the switching time can be achieved. Finally, it is shown that any two arbitrary memory cells from an MRAM array can be used to perform a logic operation. Thus, an intrinsic non-volatile logic-in-memory architecture can be realized

77 FR 72884 - Crystalline Silicon Photovoltaic Cells and Modules From China

Science.gov (United States)

2012-12-06

... Silicon Photovoltaic Cells and Modules From China Determinations On the basis of the record \\1\\ developed... imports of crystalline silicon photovoltaic cells and modules from China, provided for in subheadings 8501... silicon photovoltaic cells and modules from China. Chairman Irving A. Williamson and Commissioner Dean A...

Brownian dynamics of a protein-polymer chain complex in a solid-state nanopore

Science.gov (United States)

Wells, Craig C.; Melnikov, Dmitriy V.; Gracheva, Maria E.

2017-08-01

We study the movement of a polymer attached to a large protein inside a nanopore in a thin silicon dioxide membrane submerged in an electrolyte solution. We use Brownian dynamics to describe the motion of a negatively charged polymer chain of varying lengths attached to a neutral protein modeled as a spherical bead with a radius larger than that of the nanopore, allowing the chain to thread the nanopore but preventing it from translocating. The motion of the protein-polymer complex within the pore is also compared to that of a freely translocating polymer. Our results show that the free polymer's standard deviations in the direction normal to the pore axis is greater than that of the protein-polymer complex. We find that restrictions imposed by the protein, bias, and neighboring chain segments aid in controlling the position of the chain in the pore. Understanding the behavior of the protein-polymer chain complex may lead to methods that improve molecule identification by increasing the resolution of ionic current measurements.

Intermediate Bandgap Solar Cells From Nanostructured Silicon

Energy Technology Data Exchange (ETDEWEB)

Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

Bioinspired Surface Treatments for Improved Decontamination: Polymer Based SlipperyLiquid Infused Porous Surfaces (SLIPS)

Science.gov (United States)

2018-04-23

Materials & Interfaces 6, 1502-1508 (2014). 2. M.A. Samaha; M. Gad-el-Hak, " Polymeric Slippery Coatings: Nature and Applications," Polymers 6, 1266...organic polymers producing chains that can serve to reinforce the overall structure. The POSS variants evaluated under this study included a cage structure...cage structures of silicon and oxygen that bind to organic polymers producing large chains that can act as a reinforcing fiber (Figure 1). They are

Micromachined silicon acoustic delay line with 3D-printed micro linkers and tapered input for improved structural stability and acoustic directivity

International Nuclear Information System (INIS)

Cho, Y; Kumar, A; Xu, S; Zou, J

2016-01-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. To achieve deeper imaging depth and wider field of view, a longer delay time and therefore delay length are required. However, as the length of the delay line increases, it becomes more vulnerable to structural instability due to reduced mechanical stiffness. In this paper, we report the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, the improvement of the acoustic acceptance angle of the silicon acoustic delay lines was also investigated to better suppress the reception of unwanted ultrasound signals outside of the imaging plane. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays. (paper)

Incorporation of ester groups into low band-gap diketopyrrolopyrrole containing polymers for solar cell applications

DEFF Research Database (Denmark)

Hu, Xiaolian; Zuo, Lijian; Fu, Weifei

2012-01-01

To increase the open circuit voltage (VOC) of polymer solar cells based on diketopyrrolopyrrole (DPP) containing polymers, the weakly electron-withdrawing thiophene-3,4-dicarboxylate unit was introduced into the polymer backbone. Two ester group functionalized DPP containing polymers, PCTDPP...... with a random structure and PDCTDPP with a regular structure, were designed and synthesized by the Stille coupling reaction. The resulting copolymers exhibit broad and strong absorption bands from 350 to 1000 nm with low optical band gaps below 1.40 eV. Through cyclic voltammetry measurements, it is found...

Study on melting available silicone from coal gangue

Energy Technology Data Exchange (ETDEWEB)

Chen-tao Hou; Sheng-quan Wang; Xiao-fei Xie [Xi' an University of Science and Technology, Xi' an (China). College of Geology and Environment

2009-12-15

Available silicone was melted from coal gangue samples from Hancheng diggings through calcination, digestion, and other means. The best calcination temperature was determined from a range of 550-1150{sup o}C; and the best time, from a range of 0.5-5 h by colorimetry method. The proper ratio of coal gangue, limestone, sodium carbonate, and caustic soda was then determined through orthogonal experiment. The results show that the proper extraction condition for available silicone is the ratio of coal gangue, limestone, sodium carbonate, and caustic soda at 1:0.5:0.1:0.05, calcination temperature at 700{sup o}C, and calcination time at 2 h. In this condition, the available silicone content can be more than 19.65%. 10 refs., 2 figs., 3 tabs.

High yield silicon carbide pre-ceramic polymers

International Nuclear Information System (INIS)

Baney, R.H.

1982-01-01

Polysilanes which are substituted with (CH 3 ) 3 SiO-groups are useful for the preparation in high yields of fine grained silicon carbide ceramic materials. They consist of 0 to 60 mole % (CH 3 ) 2 Si units and 100 to 40 mole % CH 3 Si units, all Si valences not satisfied by CH 3 groups or Si atoms being directed to groups (CH 3 ) 3 SiO-, which siloxane groups amount to 23 to 61 weight % of the polysilane. They are prepared by reaction of the corresponding chloro- or bromo-methyl polysilanes with at least the stoichiometric amounts of (CH 3 ) 3 SiOSi(CH 3 ) 3 and water in the presence of a strong acid. (author)

Nanostructured silicon for photonics from materials to devices

CERN Document Server

Gaburro, Z; Daldosso, N

2006-01-01

The use of light to channel signals around electronic chips could solve several current problems in microelectronic evolution including: power dissipation, interconnect bottlenecks, input/output from/to optical communication channels, poor signal bandwidth, etc. It is unfortunate that silicon is not a good photonic material: it has a poor light-emission efficiency and exhibits a negligible electro-optical effect. Silicon photonics is a field having the objective of improving the physical properties of silicon; thus turning it into a photonic material and permitting the full convergence of elec

Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

International Nuclear Information System (INIS)

He Ying; Wang Junan; Pei Changlong; Song Jizhong; Zhu Di; Chen Jie

2010-01-01

A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

Nonlinear behavior of photoluminescence from silicon particles under two-photon excitation

International Nuclear Information System (INIS)

Xu Xingsheng; Yokoyama, Shiyoshi

2011-01-01

Two-photon excited fluorescence (TPEF) under continuous-wave excitation from silicon particles produced by a pulsed laser is investigated. Spectra and images of TPEF from silicon particles are studied under different excitation intensities and operation modes (continuous wave or pulse). It is found that the photoluminescence depends superlinearly on the excitation intensity and that the spectral shape and peaks vary with different silicon particles. The above phenomena show the nonlinear behavior of TPEF from silicon particles, and stimulated emission is a possible process.

Evidence of localized amorphous silicon clustering from Raman depth-probing of silicon nanocrystals in fused silica

International Nuclear Information System (INIS)

Barba, D; Martin, F; Ross, G G

2008-01-01

Silicon nanocrystals (Si-nc) and amorphous silicon (α-Si) produced by silicon implantation in fused silica have been studied by micro-Raman spectroscopy. Information regarding the Raman signature of the α-Si phonon excitation was extracted from Raman depth-probing measurements using the phenomenological phonon confinement model. The spectral deconvolution of the Raman measurements recorded at different laser focusing depths takes into account both the Si-nc size variation and the Si-nc spatial distribution within the sample. The phonon peak associated with α-Si around 470 cm -1 is greatest for in-sample laser focusing, indicating that the formation of amorphous silicon is more important in the region containing a high concentration of silicon excess, where large Si-nc are located. As also observed for Si-nc systems prepared by SiO x layer deposition, this result demonstrates the presence of α-Si in high excess Si implanted Si-nc systems

Spectral-luminescent investigation of polymers doped with europium trisphenoyltrifluoroacetonate compound with 1,10-phenanthroline

International Nuclear Information System (INIS)

Karasev, V.E.; Mirochnik, A.G.; Shchelokov, R.N.

1983-01-01

Spectral-luminescent characteristics of europium tristhenoyltrifluoroacetonate with 1.10-phenanthpoline in polystyrepe and polyvinyl chloride are investigated. E 4 (TTA) 3 phen during introduction into polymers preserves its composition and structure. Weak temperature dependence of half-Width of luminescent lines qualitatively different from the case of crystal chelate is characteristic for polymers doped with E 4 (TTA) 3 xphen. Investigation into temperature dependence of E 4 3+ luminescent intensity in chelate doped polymers proves the conclusion on weakening processes of excitation energy relaxation by vibration constituents of close and far environment during chelate introduction into polymers

Stages of polymer transformation during remote plasma oxidation (RPO) at atmospheric pressure

Science.gov (United States)

Luan, P.; Oehrlein, G. S.

2018-04-01

The interaction of cold temperature plasma sources with materials can be separated into two types: ‘direct’ and ‘remote’ treatments. Compared to the ‘direct’ treatment which involves energetic charged species along with short-lived, strongly oxidative neutral species, ‘remote’ treatment by the long-lived weakly oxidative species is less invasive and better for producing uniformly treated surfaces. In this paper, we examine the prototypical case of remote plasma oxidation (RPO) of polymer materials by employing a surface micro-discharge (in a N2/O2 mixture environment) treatment on polystyrene. Using material characterization techniques including real-time ellipsometry, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, the time evolution of polymer film thickness, refractive index, surface, and bulk chemical composition were evaluated. These measurements revealed three consecutive stages of polymer transformation, i.e. surface adsorption and oxidation, bulk film permeation and thickness expansion followed by the material removal as a result of RPO. By correlating the observed film thickness changes with simultaneously obtained chemical information, we found that the three stages were due to the three effects of weakly oxidative species on polymers: (1) surface oxidation and nitrate (R-ONO2) chemisorption, (2) bulk oxidation, and (3) etching. Our results demonstrate that surface adsorption and oxidation, bulk oxidation, and etching can all happen during one continuous plasma treatment. We show that surface nitrate is only adsorbed on the top few nanometers of the polymer surface. The polymer film expansion also provided evidence for the diffusion and reaction of long-lived plasma species in the polymer bulk. Besides, we found that the remote plasma etched surface was relatively rich in O-C=O (ester or carboxylic acid). These findings clarify the roles of long-lived weakly oxidative plasma species on polymers and advance

Enhanced photoluminescence from porous silicon by hydrogen-plasma etching

International Nuclear Information System (INIS)

Wang, Q.; Gu, C.Z.; Li, J.J.; Wang, Z.L.; Shi, C.Y.; Xu, P.; Zhu, K.; Liu, Y.L.

2005-01-01

Porous silicon (PS) was etched by hydrogen plasma. On the surface a large number of silicon nanocone arrays and nanocrystallites were formed. It is found that the photoluminescence of the H-etched porous silicon is highly enhanced. Correspondingly, three emission centers including red, green, and blue emissions are shown to contribute to the enhanced photoluminescence of the H-etched PS, which originate from the recombination of trapped electrons with free holes due to Si=O bonding at the surface of the silicon nanocrystallites, the quantum size confinement effect, and oxygen vacancy in the surface SiO 2 layer, respectively. In particular, the increase of SiO x (x<2) formed on the surface of the H-etched porous silicon plays a very important role in enhancing the photoluminescence properties

An array of ordered pillars with retentive properties for pressure-driven liquid chromatography fabricated directly from an unmodified cyclo olefin polymer

NARCIS (Netherlands)

Illa, Xavi; de Malsche, Wim; Bomer, Johan G.; Gardeniers, Johannes G.E.; Eijkel, Jan C.T.; Morante, Joan Ramon; Romano-Rodriguez, Albert; Desmet, Gert

2009-01-01

The current paper describes the development and characterization of a pillar array chip that is constructed out of a sandwich of cyclo olefin polymer (COP) sheets. The silicon master of a 5 cm long pillar array was embossed into the COP, yielding 4.3 µm deep pillars of 15.3 µm diameter with an

Effects of supercritical carbon dioxide on immobile bound polymer chains on solid substrates

Science.gov (United States)

Sen, Mani; Asada, Mitsunori; Jiang, Naisheng; Endoh, Maya K.; Akgun, Bulent; Satija, Sushil; Koga, Tadanori

2013-03-01

Adsorbed polymer layers formed on flat solid substrates have recently been the subject of extensive studies because it is postulated to control the dynamics of technologically relevant polymer thin films, for example, in lithography. Such adsorbed layers have been reported to hinder the mobility of polymer chains in thin films even at a large length scale. Consequently, this bound layer remains immobile regardless of processing techniques (i.e. thermal annealing, solvent dissolution, etc). Here, we investigate the use of supercritical carbon dioxide (scCO2) as a novel plasticizer for bound polystyrene layers formed on silicon substrates. In-situ swelling and interdiffusion experiments using neutron reflectivity were performed. As a result, we found the anomalous plasticization effects of scCO2 on the bound polymer layers near the critical point where the anomalous adsorption of CO2 molecules in polymer thin films has been reported previously. Acknowledgement: We acknowledge the financial support from NSF Grant No. CMMI-084626.

Development of 3D carbon nanotube interdigitated finger electrodes on polymer substrate for flexible capacitive sensor application

International Nuclear Information System (INIS)

Hu, Chih-Fan; Wang, Jhih-Yu; Fang, Weileun; Liu, Yu-Chia; Tsai, Ming-Han

2013-01-01

This study reports a novel approach to the implementation of 3D carbon nanotube (CNT) interdigitated finger electrodes on flexible polymer, and the detection of strain, bending curvature, tactile force and proximity distance are demonstrated. The merits of the presented CNT-based flexible sensor are as follows: (1) the silicon substrate is patterned to enable the formation of 3D vertically aligned CNTs on the substrate surface; (2) polymer molding on the silicon substrate with 3D CNTs is further employed to transfer the 3D CNTs to the flexible polymer substrate; (3) the CNT–polymer composite (∼70 μm in height) is employed to form interdigitated finger electrodes to increase the sensing area and initial capacitance; (4) other structures such as electrical routings, resistors and mechanical supporters are also available using the CNT–polymer composite. The preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNT interdigitated electrodes on a poly-dimethylsiloxane substrate. The tests show that the typical capacitance change is several dozens of fF and the gauge factor is in the range of 3.44–4.88 for strain and bending curvature measurement; the sensitivity of the tactile sensor is 1.11% N −1 ; a proximity distance near 2 mm away from the sensor can be detected. (paper)

Optical sensors from electrohydrodynamic jetted polymer fiber resonators

DEFF Research Database (Denmark)

Laye, Fabrice; Kraemmer, Sarah; Castillo, Alejandro

2016-01-01

Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol.......Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol....

Lanthanide Organophosphate Spiro Polymers: Synthesis, Structure, and Magnetocaloric Effect in the Gadolinium Polymer.

Science.gov (United States)

Gupta, Sandeep K; Bhat, Gulzar A; Murugavel, Ramaswamy

2017-08-07

Spirocyclic lanthanide organophosphate polymers, {[Ln(dipp)(dippH)(CH 3 OH)(H 2 O) 2 ](CH 3 OH) 2 } n [Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11)], have been prepared from the reaction of Ln(NO 3 ) 3 ·xH 2 O with sterically hindered 2,6-diisopropylphenyl phosphate (dippH 2 ) using aqueous NaOH as the base. The one-dimensional chainlike lanthanide (III) organophosphate coordination polymers have been characterized with the aid of analytical and spectroscopic methods. The single crystal structure determination of polymers (2-5 and 7-11) reveals that in these compounds the hydrophobic organic groups of the phosphate provide a protective coating for the inorganic lanthanide phosphate polymeric chain. The encapsulation of inorganic lanthanide phosphate core, which has very low solubility product, within the organic groups assists in the facile crystallization of the polymers. The di- and monoanionic organophosphate ligands dipp 2- and dippH - display [2.111] and [2.110] binding modes, respectively, in 2-5 and 7. However, they exhibit only [2.110] binding mode in the case of 8-11. This results in the formation of two different types of polymers. While the lighter rare-earth metal ions in 2-5 and 7 display eight coordinate biaugmented trigonal prismatic geometry, the heavier rare-earth metal ions in 9-11 exhibit a seven coordinate capped trigonal prismatic environment. The Tb(III) ion in 8 displays distorted pentagonal bipyramidal geometry. Magnetic studies reveal the presence of weak antiferromagnetic interactions between the Ln(III) ions through the organophosphate ligand. The isotropic Gd(III) polymer 7 exhibits a maximum entropy change of 17.83 J kg -1 K -1 for a field change of 7.0 T at 2.5 K, which is significant considering the high molecular weight of the organophosphate ligand. These polymers represent the first family of any structurally characterized rare-earth organophosphate polymers derived from monoesters

First results from the SLD silicon calorimeters

International Nuclear Information System (INIS)

Berridge, S.C.; Bugg, W.M.; Kroeger, R.S.; Weidemann, A.W.; White, S.L.

1992-07-01

The small-angle calorimeters of the SLD were successfully operated during the recent SLC engineering run. The Luminosity Monitor and Small-Angle Tagger (LMSAT) covers the angular region between 28 and 68 milliradians from the beam axis, while the Medium-Angle Silicon Calorimeter (MASC) covers the 68--190 milliradian region. Both are silicon-tungsten sampling calorimeters; the LMSAT employs 23 layers of 0.86 X 0 sampling, while the MASC has 10 layers of 1.74 X 0 sampling. We present results from the first run of the SLC with the SLD on beamline

Patterned immobilisation of silicon dioxide nanoparticles on the surface of a photosensitive polymer

Energy Technology Data Exchange (ETDEWEB)

Muhr, Nina, E-mail: nina.muhr@unileoben.ac.at [Chair of Chemistry of Polymeric Materials, University of Leoben, Otto-Gloeckel-Strasse 2, A-8700 Leoben (Austria); Grinschgl, Markus; Griesser, Thomas [Chair of Chemistry of Polymeric Materials, University of Leoben, Otto-Gloeckel-Strasse 2, A-8700 Leoben (Austria); Kern, Wolfgang [Chair of Chemistry of Polymeric Materials, University of Leoben, Otto-Gloeckel-Strasse 2, A-8700 Leoben (Austria); Polymer Competence Center Leoben GmbH, Peter-Rosegger-Strasse 12, A-8700 Leoben (Austria); Schroettner, Hartmuth [Institute for Electron Microscopy, Technical University of Graz, Steyrergasse 17, A-8010 Graz (Austria)

2012-01-01

A photosensitive co-polymer of styrene and 4-vinylbenzyl thiocyanate was synthesised and employed for the immobilisation of aminofunctionalised silica nanoparticles (SiO{sub 2}-NP) at the polymer surface. Upon UV irradiation of the co-polymer, isothiocyanate groups are generated by a photo-isomerisation reaction of the thiocyanate groups. The silica nanoparticles were selectively immobilised in irradiated areas by immersing the illuminated polymer surface in a solution of SiO{sub 2}-NP. Depending on the time of immersion and the nanoparticle concentration, different amounts of silica can be deposited in the irradiated areas, whilst no immobilisation of SiO{sub 2}-NP is observed in the non-irradiated areas. By using photolithographic methods, patterned silica structures ({mu}m scale) were produced on the polymer surface. The SiO{sub 2}-NP covered surfaces are of potential interest to generate protective surface layers and to carry out further functionalisation reactions of the immobilised SiO{sub 2}-NP particles.

Electrospun a-Si using Liquid Silane/Polymer Inks

Energy Technology Data Exchange (ETDEWEB)

Doug Schulz

2010-12-09

Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

End to end distribution functions for a class of polymer models

International Nuclear Information System (INIS)

Khandekar, D.C.; Wiegel, F.W.

1988-01-01

The two point end-to-end distribution functions for a class of polymer models have been obtained within the first cumulant approximation. The trial distribution function this purpose is chosen to correspond to a general non-local quadratic functional. An Exact expression for the trial distribution function is obtained. It is pointed out that these trial distribution functions themselves can be used to study certain aspects of the configurational behaviours of polymers. These distribution functions are also used to obtain the averaged mean square size 2 > of a polymer characterized by the non-local quadratic potential energy functional. Finally, we derive an analytic expression for 2 > of a polyelectrolyte model and show that for a long polymer a weak electrostatic interaction does not change the behaviour of 2 > from that of a free polymer. (author). 16 refs

Phase transition and luminescence properties from vapor etched silicon

International Nuclear Information System (INIS)

Aouida, S.; Saadoun, M.; Ben Saad, K.; Bessais, B.

2006-01-01

In this work, we present a study on the structure and photoluminescence (PL) properties of a non-conventional ammonium hexafluorosilicate (NH 4 ) 2 SiF 6 (white powder) obtained from HNO 3 /HF chemical vapor etching (CVE) of silicon wafers. The CVE method leads either to the formation of luminescent Porous Silicon (PS) or SiO x /Si-containing (NH 4 ) 2 SiF 6 depending on the experimental conditions. At specific conditions (i.e., HNO 3 / HF volume ratio > 1 / 4), the CVE technique can generate instead of PS, a (NH 4 ) 2 SiF 6 phase where SiO x /Si particles are embedded. The (NH 4 ) 2 SiF 6 marketed powder is not luminescent, while that obtained from silicon vapor-etching presents a noticeable intense and stable photoluminescence (PL), which was found to have mainly two shoulders at 1.98 and 2.1 eV. Two processes have been proposed to explain this PL property. First, the visible luminescence around 1.98 eV would come from silicon nanoparticles embedded in the powder, having a distribution size that does not allow SiO x species to influence their own PL. Second, the PL shoulder around 2.1 eV would originate from small silicon nanoparticles trapped in SiO x features, leading to oxide related states that may trap electrons or excitons, depending on the silicon nanoparticle size, wherein radiative recombination occurs. The PL shoulder could become broader at low temperatures suggesting the existence of radiative recombination in SiO x related defects

Sensing of environmental pollutant by conductive composite from prepared from hyperbranched polymer-grafted carbon black and crystalline polymer

International Nuclear Information System (INIS)

Taniguchi, Y.; Chen, J.; Ogawa, M.; Yokoyama, K.; Shimizu, H.; Tsubokawa, N.; Maekawa, Y.; Yoshida, M.

2002-01-01

Complete text of publication follows. The hyperbranched (HB) polymer-grafted (PG) carbon blacks (CB) have the possibility of utilizing as a support of catalyst and enzyme, and a curing agent of epoxy resin, because they have much terminal amino or hydroxyl groups. The postgrafting of crystalline polymer onto HB PG CB and the sensing of environmental pollutant by the conductive composite prepared from the polymer-postgrafted CB was discussed. The grafting of poly(amidoamide) onto CB surface was achieved by repeating either Michael addition of methyl acrylate to amino group on the surface or the amidation of the resulting terminal methyl ester group with ethylene diamine. HB polyester onto CB surface was grafted by stepwise growth of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) from surface carboxyl and hydroxyl groups on CB as a core in the presence of p-toluenesulfonic acid (p-TSA). The one-pot grafting of HB polyester onto CB as core was also achieved by the polycondensation of bis-MPA in the presence of p-TSA. Postgrafting of crystalline polymer onto HB polymer-grafted CB was achieved by the reaction of terminal amino or hydroxyl groups of grafted chain with COCl-terminated crystalline polymer. The electric resistance of the composite prepared from crystalline polymer-postgrafted CB was found to increase drastically in hexane, containing environmental pollutant, such as chloroform and trichloroethane, and returned immediately to the initial resistance when it was transferred into pure hexane. Based on the above results, it is concluded that the composite can be used as a novel sensor for environmental pollutant in solution

Silicon photonic IC embedded optical-PCB for high-speed interconnect application

Science.gov (United States)

Kallega, Rakshitha; Nambiar, Siddharth; Kumar, Abhai; Ranganath, Praveen; Selvaraja, Shankar Kumar

2018-02-01

Optical-Printed Circuit Board (PCB) is an emerging optical interconnect technology to bridge the gap between the board edge and the processing module. The technology so far has been used as a broadband transmitter using polymer waveguides in the PCB. In this paper, we report a Silicon Nitride based photonic IC embedded in the PCB along with the polymers as waveguides in the PCB. The motivation for such integration is to bring routing capability and to reduce the power loss due to broadcasting mode.

All-optical switching via four-wave mixing Bragg scattering in a silicon platform

Directory of Open Access Journals (Sweden)

Yun Zhao

2017-02-01

Full Text Available We employ the process of non-degenerate four-wave mixing Bragg scattering to demonstrate all-optical control in a silicon platform. In our configuration, a strong, non-information-carrying pump is mixed with a weak control pump and an input signal in a silicon-on-insulator waveguide. Through the optical nonlinearity of this highly confining waveguide, the weak pump controls the wavelength conversion process from the signal to an idler, leading to a controlled depletion of the signal. The strong pump, on the other hand, plays the role of a constant bias. In this work, we show experimentally that it is possible to implement this low-power switching technique as a first step towards universal optical logic gates, and test the performance with random binary data. Even at very low powers, where the signal and control pump levels are almost equal, the eye-diagrams remain open, indicating a successful operation of the logic gates.

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

Directory of Open Access Journals (Sweden)

Yuandong Sun

2017-01-01

Full Text Available Silicon is regarded as the next generation anode material for LIBs with its ultra-high theoretical capacity and abundance. Nevertheless, the severe capacity degradation resulting from the huge volume change and accumulative solid-electrolyte interphase (SEI formation hinders the silicon based anode material for further practical applications. Hence, a variety of methods have been applied to enhance electrochemical performances in terms of the electrochemical stability and rate performance of the silicon anodes such as designing nanostructured Si, combining with carbonaceous material, exploring multifunctional polymer binders, and developing artificial SEI layers. Silicon anodes with low-dimensional structures (0D, 1D, and 2D, compared with bulky silicon anodes, are strongly believed to have several advanced characteristics including larger surface area, fast electron transfer, and shortened lithium diffusion pathway as well as better accommodation with volume changes, which leads to improved electrochemical behaviors. In this review, recent progress of silicon anode synthesis methodologies generating low-dimensional structures for lithium ion batteries (LIBs applications is listed and discussed.

Nanoparticles from Renewable Polymers

Directory of Open Access Journals (Sweden)

Frederik Roman Wurm

2014-07-01

Full Text Available The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights polysaccharides, polyesters, lignin or by complex structure (proteins, lignin. This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications.

Influence of acceptor on charge mobility in stacked π-conjugated polymers

Science.gov (United States)

Sun, Shih-Jye; Menšík, Miroslav; Toman, Petr; Gagliardi, Alessio; Král, Karel

2018-02-01

We present a quantum molecular model to calculate mobility of π-stacked P3HT polymer layers with electron acceptor dopants coupled next to side groups in random position with respect to the linear chain. The hole density, the acceptor LUMO energy and the hybridization transfer integral between the acceptor and polymer were found to be very critical factors to the final hole mobility. For a dopant LUMO energy close and high above the top of the polymer valence band we have found a significant mobility increase with the hole concentration and with the dopant LUMO energy approaching the top of the polymer valence band. Higher mobility was achieved for small values of hybridization transfer integral between polymer and the acceptor, corresponding to the case of weakly bound acceptor. Strong couplings between the polymer and the acceptor with Coulomb repulsion interactions induced from the electron localizations was found to suppress the hole mobility.

Thermal conductivity of silicon nanocrystals and polystyrene nanocomposite thin films

International Nuclear Information System (INIS)

Juangsa, Firman Bagja; Muroya, Yoshiki; Nozaki, Tomohiro; Ryu, Meguya; Morikawa, Junko

2016-01-01

Silicon nanocrystals (SiNCs) are well known for their size-dependent optical and electronic properties; they also have the potential for low yet controllable thermal properties. As a silicon-based low-thermal conductivity material is required in microdevice applications, SiNCs can be utilized for thermal insulation. In this paper, SiNCs and polymer nanocomposites were produced, and their thermal conductivity, including the density and specific heat, was measured. Measurement results were compared with thermal conductivity models for composite materials, and the comparison shows a decreasing value of the thermal conductivity, indicating the effect of the size and presence of the nanostructure on the thermal conductivity. Moreover, employing silicon inks at room temperature during the fabrication process enables a low cost of fabrication and preserves the unique properties of SiNCs. (paper)

Photoluminescence and electrical properties of silicon oxide and silicon nitride superlattices containing silicon nanocrystals

International Nuclear Information System (INIS)

Shuleiko, D V; Ilin, A S

2016-01-01

Photoluminescence and electrical properties of superlattices with thin (1 to 5 nm) alternating silicon-rich silicon oxide or silicon-rich silicon nitride, and silicon oxide or silicon nitride layers containing silicon nanocrystals prepared by plasma-enhanced chemical vapor deposition with subsequent annealing were investigated. The entirely silicon oxide based superlattices demonstrated photoluminescence peak shift due to quantum confinement effect. Electrical measurements showed the hysteresis effect in the vicinity of zero voltage due to structural features of the superlattices from SiOa 93 /Si 3 N 4 and SiN 0 . 8 /Si 3 N 4 layers. The entirely silicon nitride based samples demonstrated resistive switching effect, comprising an abrupt conductivity change at about 5 to 6 V with current-voltage characteristic hysteresis. The samples also demonstrated efficient photoluminescence with maximum at ∼1.4 eV, due to exiton recombination in silicon nanocrystals. (paper)

Process Development in the Preparation and Characterization of Silicon Alkoxide From Rice Husk

International Nuclear Information System (INIS)

Khin San Win; Toe Shein; Nyunt Wynn

2011-12-01

The preparation and characterization of silicon alkoxide (silicon isopropoxide) from rice husk char has been studied. In the investigation, four kinds of Myanmar paddies were chemically assayed. Analyses showed the silicon contend varies from 73-92% . Based on the silicon content, the process development in the production of silicon isopropoxide was carried out. In the process development, silicon isopropoxide with a yield of 44.21% was achieved by the direct reaction of isopropanol in situ by silicon tetrachloride, which was directly produced by the chlorination of rice husk char at the high temperature range of 900-1100 C. The novelity of the process was that, silicon isopropoxide was achieved in situ and not by using the old process, where generally isopropanol was reacted with silicon tetrachloride. The physiochemical properties of silicon isopropoxide was confirmed by conventional and modern techniques. In the investigation, the starting materials, silica in the reaction products were characterized, identified and confirmed by modren techniques. Silicon isopropoxide can be a sources of pore silica whereby silicon of 97-99% of purity can be achieved.

Gamma rays from fast neutron capture in silicon and sulphur

International Nuclear Information System (INIS)

Lindholm, A.; Nilsson, L.; Bergqvist, I.

1975-01-01

Gamma-ray spectra from neutron capture in natural samples of silicon and sulphur have been recorded at eight neutron energies between 4 and 15 MeV. Time-of-flight techniques were used to improve the signal-to-background ratio and the gamma radiation was detected by a large NaI(Tl) scintillator. Cross sections have been determined for transitions to individual (or groups of) levels in the final nucleus. Calculations based on the direct-semidirect model show that this model gives a reasonable description of the shapes of the gamma-ray spectra, but fails to account for observed excitation functions. The inclusion of the compound-nucleus capture process gives a conclusive improvement in the description of the excitation functions, in particular at low neutron energies. The ability of the compound-nucleus model to account for the shapes of the gamma-ray spectra is as good as that of the direct-semidirect model. At higher neutron energies, an improvement is obtained for transitions to the region of weakly bound levels, where the single-particle structure is poorly known. (Auth.)

Design of Polymer Wavelength Splitter 1310 nm/1550 nm Based on Multimode Interferences

Directory of Open Access Journals (Sweden)

V. Prajzler

2010-12-01

Full Text Available We report about design of 1x2 1310/1550 nm optical wavelength division multiplexer based on polymer waveguides. The polymer splitter was designed by using RSoft software based on beam propagation method. Epoxy novolak resin polymer was used as core waveguides layer, silicon substrate with silica layer was used as buffer layer and polymethylmethacrylate was used as protection cover layer. The simulation shows that the output energy for the fundamental mode is 67.1 % for 1310 nm and 67.8 % for 1550 nm wavelength.

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)

Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix

International Nuclear Information System (INIS)

Baney, Ronald

2008-01-01

The objective of this project has been to identify a process for separating transuranic species from silicon carbide (SiC). Silicon carbide has become one of the prime candidates for the matrix in inert matrix fuels, (IMF) being designed to reduce plutonium inventories and the long half-lives actinides through transmutation since complete reaction is not practical it become necessary to separate the non-transmuted materials from the silicon carbide matrix for ultimate reprocessing. This work reports a method for that required process

Gas microstrip detectors on polymer, silicon and glass substrates

International Nuclear Information System (INIS)

Barasch, E.F.; Demroff, H.P.; Drew, M.M.; Elliott, T.S.; Gaedke, R.M.; Goss, L.T.; Kasprowicz, T.B.; Lee, B.; Mazumdar, T.K.; McIntyre, P.M.; Pang, Y.; Smith, D.D.; Trost, H.J.; Vanstraelen, G.; Wahl, J.

1993-01-01

We present results on the performance of Gas Microstrip Detectors on various substrates. These include a 300 μm anode-anode pitch pattern on Tempax borosilicate glass and ABS/copolyether, a 200 μm pattern on Upilex ''S'' polyimide, Texin 4215, Tedlar, ion-implanted Kapton, orientation-dependent etched flat-topped silicon (''knife-edge chamber''), and iron-vanadium glass, and a 100 μm pitch pattern on Upilex ''S'' and ion-implanted Kapton. (orig.)

Synthesis of thermoresponsive poly(N-isopropylacrylamide) brush on silicon wafer surface via atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Turan, Eylem; Demirci, Serkan [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey); Caykara, Tuncer, E-mail: caykara@gazi.edu.t [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey)

2010-08-31

Thermoresponsive poly(N-isopropylacrylamide) [poly(NIPAM)] brush on silicon wafer surface was prepared by combining the self-assembled monolayer of initiator and atom transfer radical polymerization (ATRP). The resulting polymer brush was characterized by in situ reflectance Fourier transform infrared spectroscopy, atomic force microscopy and ellipsometry techniques. Gel permeation chromatography determination of the number-average molecular weight and polydispersity index of the brush detached from the silicon wafer surface suggested that the surface-initiated ATRP method can provide relatively homogeneous polymer brush. Contact angle measurements exhibited a two-stage increase upon heating over the board temperature range 25-45 {sup o}C, which is in contrast to the fact that free poly(NIPAM) homopolymer in aqueous solution exhibits a phase transition at ca. 34 {sup o}C within a narrow temperature range. The first de-wetting transition takes place at 27 {sup o}C, which can be tentatively attributed to the n-cluster induced collapse of the inner region of poly(NIPAM) brush close to the silicon surface; the second de-wetting transition occurs at 38 {sup o}C, which can be attributed to the outer region of poly(NIPAM) brush, possessing much lower chain density compared to that of the inner part.

Amphiphilic invertible polymers: Self-assembly into functional materials driven by environment polarity

Science.gov (United States)

Hevus, Ivan

nanoparticles strongly differing in polarity. AIP modified silica nanoparticles are able to adsolubilize molecules of poorly water-soluble 2-naphthol into the adsorbed polymer layer. The adsolubilization ability of adsorbed invertible macromolecules makes AIP-modified silica nanoparticles potentially useful in wastewater treatment or biomedical applications. Finally, the invertible micellar assemblies were used as functional additives to improve the appearance of electrospun silicon wires based on cyclohexasilane, a liquid silicon precursor. AIP-assisted fabrication of silicon wires from the liquid cyclohexasilane precursor has potential as a scalable method for developing electronic functional materials.

Position calibration of silicon strip detector using quasi-elastic scattering of 16O+197Au

International Nuclear Information System (INIS)

Yan Wenqi; Hu Hailong; Zhang Gaolong

2013-01-01

Background: Elastic scattering is induced by weakly unstable nuclei. Generally, a good angular resolution for angular distribution of elastic scattering is needed. The silicon strip detector is often used for this kind of experiment. Purpose: In order to use silicon strip detector to study the elastic scattering of weakly unbound nuclei, it is important to get the information of its position calibration. It is well known that the elastic scattering of stable nuclei has a good angular distribution and many experimental data have been obtained. Methods: So the scattering of stable nuclei can be used to calibrate the position information of silicon strip detector. In this experiment, the positions of silicon strip detectors are calibrated using 101 MeV and 59 MeV 16 O scattering on the 197 Au target. Results: The quasi-elastic peaks can be observed in the silicon strip detectors and the counts of quasi-elastic 16 O can be obtained. The solid angles of the silicon strip detectors are calibrated by using alpha source which has three alpha energy values. The angular distribution of quasi-elastic scattering of 16 O+ 197 Au is obtained at these two energy values. Conclusions: The experimental data of angular distribution are reasonable and fit for the principle of angular distribution of elastic scattering. It is concluded that in the experiment these silicon strip detectors can accurately give the position information and can be used for the elastic scattering experiment. (authors)

Novel technique for reliability testing of silicon integrated circuits

NARCIS (Netherlands)

Le Minh, P.; Wallinga, Hans; Woerlee, P.H.; van den Berg, Albert; Holleman, J.

2001-01-01

We propose a simple, inexpensive technique with high resolution to identify the weak spots in integrated circuits by means of a non-destructive photochemical process in which photoresist is used as the photon detection tool. The experiment was done to localize the breakdown link of thin silicon

A high voltage DC-DC converter driving a Dielectric Electro Active Polymer actuator for wind turbine flaps

DEFF Research Database (Denmark)

Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

2012-01-01

The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result...

Integrated Electromechanical Transduction Schemes for Polymer MEMS Sensors

Directory of Open Access Journals (Sweden)

Damien Thuau

2018-04-01

Full Text Available Polymer Micro ElectroMechanical Systems (MEMS have the potential to constitute a powerful alternative to silicon-based MEMS devices for sensing applications. Although the use of commercial photoresists as structural material in polymer MEMS has been widely reported, the integration of functional polymer materials as electromechanical transducers has not yet received the same amount of interest. In this context, we report on the design and fabrication of different electromechanical schemes based on polymeric materials ensuring different transduction functions. Piezoresistive transduction made of carbon nanotube-based nanocomposites with a gauge factor of 200 was embedded within U-shaped polymeric cantilevers operating either in static or dynamic modes. Flexible resonators with integrated piezoelectric transduction were also realized and used as efficient viscosity sensors. Finally, piezoelectric-based organic field effect transistor (OFET electromechanical transduction exhibiting a record sensitivity of over 600 was integrated into polymer cantilevers and used as highly sensitive strain and humidity sensors. Such advances in integrated electromechanical transduction schemes should favor the development of novel all-polymer MEMS devices for flexible and wearable applications in the future.

Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography

Science.gov (United States)

Van Elburg, Devin J.; Noble, Scott D.; Hagey, Simone; Goertzen, Andrew L.

2018-03-01

Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials (‘100MP’, ‘A100’, and ‘GPA’) were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude

Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography.

Science.gov (United States)

Van Elburg, Devin J; Noble, Scott D; Hagey, Simone; Goertzen, Andrew L

2018-02-26

Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials ('100MP', 'A100', and 'GPA') were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude degradation

Extending Moore’s Law for Silicon CMOS using More-Moore and More-than-Moore Technologies

KAUST Repository

Hussain, Aftab M.

2016-12-01

With the advancement of silicon electronics under threat from physical limits to dimensional scaling, the International Technology Roadmap for Semiconductors (ITRS) released a white paper in 2008, detailing the ways in which the semiconductor industry can keep itself continually growing in the twenty-first century. Two distinct paths were proposed: More-Moore and More-than-Moore. While More-Moore approach focuses on the continued use of state-of-the-art, complementary metal oxide semiconductor (CMOS) technology for next generation electronics, More-than-Moore approach calls for a disruptive change in the system architecture and integration strategies. In this doctoral thesis, we investigate both the approaches to obtain performance improvement in the state-of-the-art, CMOS electronics. We present a novel channel material, SiSn, for fabrication of CMOS circuits. This investigation is in line with the More-Moore approach because we are relying on the established CMOS industry infrastructure to obtain an incremental change in the integrated circuit (IC) performance by replacing silicon channel with SiSn. We report a simple, low-cost and CMOS compatible process for obtaining single crystal SiSn wafers. Tin (Sn) is deposited on silicon wafers in the form of a metallic thin film and annealed to facilitate diffusion into the silicon lattice. This diffusion provides for sufficient SiSn layer at the top surface for fabrication of CMOS devices. We report a lowering of band gap and enhanced mobility for SiSn channel MOSFETs compared to silicon control devices. We also present a process for fabrication of vertically integrated flexible silicon to form 3D integrated circuits. This disruptive change in the state-of-the-art, in line with the More-than-Moore approach, promises to increase the performance per area of a silicon chip. We report a process for stacking and bonding these pieces with polymeric bonding and interconnecting them using copper through silicon vias (TSVs). We

Controlled release of tocopherols from polymer blend films

Science.gov (United States)

Obinata, Noe

Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies

Gloss and Stain Resistance of Ceramic-Polymer CAD/CAM Restorative Blocks.

Science.gov (United States)

Lawson, Nathaniel C; Burgess, John O

2016-03-01

To evaluate the gloss and stain resistance of several new ceramic-polymer CAD/CAM blocks Specimens (4 mm) were sectioned from: Enamic (polymer-infused ceramic), LAVA Ultimate (nano-ceramic reinforced polymer), e.max (lithium disilicate), Paradigm C (porcelain), and Paradigm MZ100 (composite). Specimens were wet polished on a polishing wheel to either 320 grit silicon paper (un-polished, N = 8) or 2000 grit silicon carbide papers followed by a 0.05 μm alumina slurry (polished, N = 8). Initial gloss and color (L*a*b*) values were measured. Specimens were stored in a staining solution at 37°C in darkness for 12 days (simulating 1 year). After storage, L*a*b* values re-measured. Change in color was reported as ΔE00 based on the CIEDE2000 formula. Gloss and ΔE00 were analyzed by two-way analysis of variance (ANOVA) (alpha = .05). Separate one-way ANOVA and Tukey post-hoc analyses were performed for both polish conditions and all materials. Two-way ANOVA showed that factors material, polish and their interaction were significant for both gloss and ΔE00 (p gloss and less color change than all other materials. The composition and polish of CAD/CAM materials affects gloss and stain resistance. Ceramic-polymer hybrid materials can achieve the high gloss required for esthetic restorations. These materials should be polished in order to minimize staining. If polished, all of the tested materials exhibited clinically acceptable color changes at 1 year of simulated staining. (J Esthet Restor Dent 28:S40-S45, 2016). © 2015 Wiley Periodicals, Inc.

Touch-mode capacitive pressure sensor with graphene-polymer heterostructure membrane

Science.gov (United States)

Berger, Christian; Phillips, Rory; Pasternak, Iwona; Sobieski, Jan; Strupinski, Wlodek; Vijayaraghavan, Aravind

2018-01-01

We describe the fabrication and characterisation of a touch-mode capacitive pressure sensor (TMCPS) with a robust design that comprises a graphene-polymer heterostructure film, laminated onto the silicon dioxide surface of a silicon wafer, incorporating a SU-8 spacer grid structure. The spacer grid structure allows the flexible graphene-polymer film to be partially suspended above the substrate, such that a pressure on the membrane results in a reproducible deflection, even after exposing the membrane to pressures over 10 times the operating range. Sensors show reproducible pressure transduction in water submersion at varying depths under static and dynamic loading. The measured capacitance change in response to pressure is in good agreement with an analytical model of clamped plates in touch mode. The device shows a pressure sensitivity of 27.1 +/- 0.5 fF Pa-1 over a pressure range of 0.5 kPa-8.5 kPa. In addition, we demonstrate the operation of this device as a force-touch sensor in air.

Determination of parameters for successful spray coating of silicon microneedle arrays.

Science.gov (United States)

McGrath, Marie G; Vrdoljak, Anto; O'Mahony, Conor; Oliveira, Jorge C; Moore, Anne C; Crean, Abina M

2011-08-30

Coated microneedle patches have demonstrated potential for effective, minimally invasive, drug and vaccine delivery. To facilitate cost-effective, industrial-scale production of coated microneedle patches, a continuous coating method which utilises conventional pharmaceutical processes is an attractive prospect. Here, the potential of spray-coating silicon microneedle patches using a conventional film-coating process was evaluated and the key process parameters which impact on coating coalescence and weight were identified by employing a fractional factorial design to coat flat silicon patches. Processing parameters analysed included concentration of coating material, liquid input rate, duration of spraying, atomisation air pressure, gun-to-surface distance and air cap setting. Two film-coating materials were investigated; hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose (CMC). HPMC readily formed a film-coat on silicon when suitable spray coating parameter settings were determined. CMC films required the inclusion of a surfactant (1%, w/w Tween 80) to facilitate coalescence of the sprayed droplets on the silicon surface. Spray coating parameters identified by experimental design, successfully coated 280μm silicon microneedle arrays, producing an intact film-coat, which follows the contours of the microneedle array without occlusion of the microneedle shape. This study demonstrates a novel method of coating microneedle arrays with biocompatible polymers using a conventional film-coating process. It is the first study to indicate the thickness and roughness of coatings applied to microneedle arrays. The study also highlights the importance of identifying suitable processing parameters when film coating substrates of micron dimensions. The ability of a fractional factorial design to identify these critical parameters is also demonstrated. The polymer coatings applied in this study can potentially be drug loaded for intradermal drug and vaccine delivery

Gold-coated silicon nanowire-graphene core-shell composite film as a polymer binder-free anode for rechargeable lithium-ion batteries

Science.gov (United States)

Kim, Han-Jung; Lee, Sang Eon; Lee, Jihye; Jung, Joo-Yun; Lee, Eung-Sug; Choi, Jun-Hyuk; Jung, Jun-Ho; Oh, Minsub; Hyun, Seungmin; Choi, Dae-Geun

2014-07-01

We designed and fabricated a gold (Au)-coated silicon nanowires/graphene (Au-SiNWs/G) hybrid composite as a polymer binder-free anode for rechargeable lithium-ion batteries (LIBs). A large amount of SiNWs for LIB anode materials can be prepared by metal-assisted chemical etching (MaCE) process. The Au-SiNWs/G composite film on current collector was obtained by vacuum filtration using an anodic aluminum oxide (AAO) membrane and hot pressing method. Our experimental results show that the Au-SiNWs/G composite has a stable reversible capacity of about 1520 mA h/g which was maintained for 20 cycles. The Au-SiNWs/G composite anode showed much better cycling performance than SiNWs/polyvinylidene fluoride (PVDF)/Super-P, SiNWs/G composite, and pure SiNWs anodes. The improved electrochemical properties of the Au-SiNWs/G composite anode material is mainly ascribed to the composite's porous network structure.

Ionic Liquids in Polymer Design: From Energy to Health

Science.gov (United States)

2016-10-19

of Papers published in non peer- reviewed journals: Final Report: Ionic Liquids in Polymer Design: From Energy to Health Report Title ACS Symposium...SECURITY CLASSIFICATION OF: ACS Symposium: Ionic Liquids in Polymer Design: From Energy to Health at Fall 2015 ACS Meeting in Boston, MA The...combination of ionic liquids and polymers has emerged as an active field of exploration in polymer science, where new materials have be realized for

Influence of sample oxidation on the nature of optical luminescence from porous silicon

International Nuclear Information System (INIS)

Coulthard, I.; Antel, W. J. Jr.; Freeland, J. W.; Sham, T. K.; Naftel, S. J.; Zhang, P.

2000-01-01

Site-selective luminescence experiments were performed upon porous-silicon samples exposed to varying degrees of oxidation. The source of different luminescence bands was determined to be due to either quantum confinement in nanocrystalline silicon or defective silicon oxide. Of particular interest is the defective silicon-oxide luminescence band found at 2.1 eV, which was found to frequently overlap with a luminescence band from nanocrystalline silicon. Some of the historical confusion and debate with regards to the source of luminescence from porous silicon can be attributed to this overlap. (c) 2000 American Institute of Physics

Porous Silicon Structures as Optical Gas Sensors.

Science.gov (United States)

Levitsky, Igor A

2015-08-14

We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers) are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

Hybrid Photonic Integration on a Polymer Platform

Directory of Open Access Journals (Sweden)

Ziyang Zhang

2015-09-01

Full Text Available To fulfill the functionality demands from the fast developing optical networks, a hybrid integration approach allows for combining the advantages of various material platforms. We have established a polymer-based hybrid integration platform (polyboard, which provides flexible optical input/ouptut interfaces (I/Os that allow robust coupling of indium phosphide (InP-based active components, passive insertion of thin-film-based optical elements, and on-chip attachment of optical fibers. This work reviews the recent progress of our polyboard platform. On the fundamental level, multi-core waveguides and polymer/silicon nitride heterogeneous waveguides have been fabricated, broadening device design possibilities and enabling 3D photonic integration. Furthermore, 40-channel optical line terminals and compact, bi-directional optical network units have been developed as highly functional, low-cost devices for the wavelength division multiplexed passive optical network. On a larger scale, thermo-optic elements, thin-film elements and an InP gain chip have been integrated on the polyboard to realize a colorless, dual-polarization optical 90° hybrid as the frontend of a coherent receiver. For high-end applications, a wavelength tunable 100Gbaud transmitter module has been demonstrated, manifesting the joint contribution from the polyboard technology, high speed polymer electro-optic modulator, InP driver electronics and ceramic electronic interconnects.

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

International Nuclear Information System (INIS)

Cimino, R.; Neimark, A. V.; Rasmussen, C. J.

2013-01-01

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

Energy Technology Data Exchange (ETDEWEB)

Cimino, R.; Neimark, A. V., E-mail: aneimark@rutgers.edu [Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854 (United States); Rasmussen, C. J. [DuPont Central Research and Development, Corporate Center for Analytical Sciences, Macromolecular Characterization, Route 141 and Henry Clay, Wilmington, Delaware 19803 (United States)

2013-11-28

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy.

Isotopically varying spectral features of silicon-vacancy in diamond

International Nuclear Information System (INIS)

Dietrich, Andreas; Jahnke, Kay D; Binder, Jan M; Rogers, Lachlan J; Jelezko, Fedor; Teraji, Tokuyuki; Isoya, Junichi

2014-01-01

The silicon-vacancy centre (SiV − ) in diamond has exceptional spectral properties for single-emitter quantum information applications. Most of the fluorescence is concentrated in a strong zero phonon line (ZPL), with a weak phonon sideband extending for 100 nm that contains several clear features. We demonstrate that the ZPL position can be used to reliably identify the silicon isotope present in a single SiV − centre. This is of interest for quantum information applications since only the 29 Si isotope has nuclear spin. In addition, we show that the sharp 64 meV phonon peak is due to a local vibrational mode of the silicon atom. The presence of a local mode suggests a plausible origin of the measured isotopic shift of the ZPL. (paper)

Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

Science.gov (United States)

Whitman, Pamela K.; Feke, Donald L.

1986-01-01

The effects of various powder treatment strategies on the colloid chemistry of aqueous dispersions of silicon carbide and silicon nitride are examined using a surface titration methodology. Pretreatments are used to differentiate between the true surface chemistry of the powders and artifacts resulting from exposure history. Silicon nitride powders require more extensive pretreatment to reveal consistent surface chemistry than do silicon carbide powders. As measured by titration, the degree of proton adsorption from the suspending fluid by pretreated silicon nitride and silicon carbide powders can both be made similar to that of silica.

Kerfless epitaxial silicon wafers with 7 ms carrier lifetimes and a wide lift-off process window

Science.gov (United States)

Gemmel, Catherin; Hensen, Jan; David, Lasse; Kajari-Schröder, Sarah; Brendel, Rolf

2018-04-01

Silicon wafers contribute significantly to the photovoltaic module cost. Kerfless silicon wafers that grow epitaxially on porous silicon (PSI) and are subsequently detached from the growth substrate are a promising lower cost drop-in replacement for standard Czochralski (Cz) wafers. However, a wide technological processing window appears to be a challenge for this process. This holds in particularly for the etching current density of the separation layer that leads to lift-off failures if it is too large or too low. Here we present kerfless PSI wafers of high electronic quality that we fabricate on weakly reorganized porous Si with etch current densities varying in a wide process window from 110 to 150 mA/cm2. We are able to detach all 17 out of 17 epitaxial wafers. All wafers exhibit charge carrier lifetimes in the range of 1.9 to 4.3 ms at an injection level of 1015 cm-3 without additional high-temperature treatment. We find even higher lifetimes in the range of 4.6 to 7.0 ms after applying phosphorous gettering. These results indicate that a weak reorganization of the porous layer can be beneficial for a large lift-off process window while still allowing for high carrier lifetimes.

Influence of substrate and film thickness on polymer LIPSS formation

Energy Technology Data Exchange (ETDEWEB)

Cui, Jing; Nogales, Aurora; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, Madrid 28006 (Spain); Rebollar, Esther, E-mail: e.rebollar@csic.es [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, Madrid 28006 (Spain)

2017-02-01

Highlights: • The estimation of temperature upon pulse accumulation shows that a small positive offset is caused by each individual pulse. • Number of pulses needed for LIPSS formation in PS thin films depends on polymer thickness. • Thermal conductivity and diffusivity of supporting substrate influence the onset for LIPSS formation and their quality. • Quality of LIPSS is affected by the substrate optical properties. - Abstract: Here we focus on the influence of both, substrate and film thickness on polymer Laser Induced Periodic Surface Structures (LIPSS) formation in polymer films. For this aim a morphological description of ripples structures generated on spin-coated polystyrene (PS) films by a linearly polarized laser beam with a wavelength of 266 nm is presented. The influence of different parameters on the quality and characteristics of the formed laser-induced periodic surface structures (LIPSS) was investigated. We found that well-ordered LIPSS are formed either on PS films thinner than 200 nm or thicker than 400 nm supported on silicon substrates as well as on thicker free standing films. However less-ordered ripples are formed on silicon supported films with intermediate thicknesses in the range of 200–380 nm. The effect of the thermal and optical properties of the substrate on the quality of LIPSS was analyzed. Differences observed in the fluence and number of pulses needed for the onset of surface morphological modifications is explained considering two main effects which are: (1) The temperature increase on polymer surface induced by the action of cumulative laser irradiation and (2) The differences in thermal conductivity between the polymer and the substrate which strongly affect the heat dissipation generated by irradiation.

Confined silicon nanospheres by biomass lignin for stable lithium ion battery

Science.gov (United States)

Niu, Xiaoying; Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Yan, Chenglin

2017-10-01

Biomass lignin, as a significant renewable resource, is one of the most abundant natural polymers in the world. Here, we report a novel silicon-based material, in which lignin-derived functional conformal network crosslinks the silicon nanoparticles via self-assembly. This newly-developed material could greatly solve the problems of large volume change during lithiation/delithiation process and the formation of unstable solid electrolyte interphase layers on the silicon surface. With this anode, the battery demonstrates a high capacity of ˜3000 mA h g-1, a highly stable cycling retention (˜89% after 100 cycles at 300 mA g-1) and an excellent rate capability (˜800 mA h g-1 at 9 A g-1). Moreover, the feasibility of full lithium-ion batteries with the novel silicon-based material would provide wide range of applications in the field of flexible energy storage systems for wearable electronic devices.

Measurement of MOS current mismatch in the weak inversion region

International Nuclear Information System (INIS)

Forti, F.; Wright, M.E.

1994-01-01

The MOS transistor matching properties in the weak inversion region have not received, in the past, the attention that the mismatch in the strong inversion region has. The importance of weak inversion biased transistors in low power CMOS analog systems calls for more extensive data on the mismatch in this region of operation. The study presented in this paper was motivated by the need of controlling the threshold matching in a low power, low noise amplifier discriminator circuit used in a silicon radiation detector read-out, where both the transistor dimensions and the currents had to be kept to a minimum. The authors have measured the current matching properties of MOS transistors operated in the weak inversion region. They measured a total of about 1,400 PMOS and NMOS transistors produced in four different processes and report here the results in terms of mismatch dependence on current density, device dimensions, and substrate voltage, without using any specific model for the transistor

Water-Soluble Polymers with Strong Photoluminescence through an Eco-Friendly and Low-Cost Route.

Science.gov (United States)

Guo, Zhaoyan; Ru, Yue; Song, Wenbo; Liu, Zhenjie; Zhang, Xiaohong; Qiao, Jinliang

2017-07-01

Photoluminescence (PL) of nonconjugated polymers brings a favorable opportunity for low-cost and nontoxic luminescent materials, while most of them still exhibit relatively weak emission. Strong PL from poly[(maleic anhydride)-alt-(vinyl acetate)] (PMV) from low-cost monomer has been found in organic solvents, yet the necessity of noxious solvents would hinder its practical applications. Herein, through a novel, eco-friendly, and one-step route, PMV-derived PL polymers can be fabricated with the highest quantum yield of 87% among water-soluble nonconjugated PL polymers ever reported. These PMV-derived polymers emit strong blue emission in both solutions and solids, and can be transformed into red-emission agents easily. These PL polymers exhibit application potentials in light-conversion agricultural films. It is assumed that this work not only puts forward a convenient preparation routine for nonconjugated polymers with high PL, but also provides an industrial application possibility for them. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

Directory of Open Access Journals (Sweden)

Abdullah Uzum

2017-01-01

Full Text Available Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1 without antireflection coating (ARC layer, (2 with TiO2-compact ARC film, and (3 with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88% owing to the multilayer ARC. Jsc was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2 when compared with a single TiO2-compact ARC.

Laser shock ignition of porous silicon based nano-energetic films

International Nuclear Information System (INIS)

Plummer, A.; Gascooke, J.; Shapter, J.; Kuznetsov, V. A.; Voelcker, N. H.

2014-01-01

Nanoporous silicon films on a silicon wafer were loaded with sodium perchlorate and initiated using illumination with infrared laser pulses to cause laser thermal ignition and laser-generated shock waves. Using Photon Doppler Velocimetry, it was determined that these waves are weak stress waves with a threshold intensity of 131 MPa in the silicon substrate. Shock generation was achieved through confinement of a plasma, generated upon irradiation of an absorptive paint layer held against the substrate side of the wafer. These stress waves were below the threshold required for sample fracturing. Exploiting either the laser thermal or laser-generated shock mechanisms of ignition may permit use of pSi energetic materials in applications otherwise precluded due to their environmental sensitivity

Laser shock ignition of porous silicon based nano-energetic films

Energy Technology Data Exchange (ETDEWEB)

Plummer, A.; Gascooke, J.; Shapter, J. [School of Chemical and Physical Sciences, Flinders University, 5042, Bedford Park (Australia); Centre of Expertise in Energetic Materials (CEEM), Bedford Park (Australia); Kuznetsov, V. A., E-mail: nico.voelcker@unisa.edu.au, E-mail: Valerian.Kuznetsov@dsto.defence.gov.au [School of Chemical and Physical Sciences, Flinders University, 5042, Bedford Park (Australia); Centre of Expertise in Energetic Materials (CEEM), Bedford Park (Australia); Weapons and Combat Systems Division, Defence Science and Technology Organisation, Edinburgh 5111 (Australia); Voelcker, N. H., E-mail: nico.voelcker@unisa.edu.au, E-mail: Valerian.Kuznetsov@dsto.defence.gov.au [Mawson Institute, University of South Australia, 5095, Mawson Lakes (Australia)

2014-08-07

Nanoporous silicon films on a silicon wafer were loaded with sodium perchlorate and initiated using illumination with infrared laser pulses to cause laser thermal ignition and laser-generated shock waves. Using Photon Doppler Velocimetry, it was determined that these waves are weak stress waves with a threshold intensity of 131 MPa in the silicon substrate. Shock generation was achieved through confinement of a plasma, generated upon irradiation of an absorptive paint layer held against the substrate side of the wafer. These stress waves were below the threshold required for sample fracturing. Exploiting either the laser thermal or laser-generated shock mechanisms of ignition may permit use of pSi energetic materials in applications otherwise precluded due to their environmental sensitivity.

Packaging of silicon sensors for microfluidic bio-analytical applications

International Nuclear Information System (INIS)

Wimberger-Friedl, Reinhold; Prins, Menno; Megens, Mischa; Dittmer, Wendy; Witz, Christiane de; Nellissen, Ton; Weekamp, Wim; Delft, Jan van; Ansems, Will; Iersel, Ben van

2009-01-01

A new industrial concept is presented for packaging biosensor chips in disposable microfluidic cartridges to enable medical diagnostic applications. The inorganic electronic substrates, such as silicon or glass, are integrated in a polymer package which provides the electrical and fluidic interconnections to the world and provides mechanical strength and protection for out-of-lab use. The demonstrated prototype consists of a molded interconnection device (MID), a silicon-based giant magneto-resistive (GMR) biosensor chip, a flex and a polymer fluidic part with integrated tubing. The various processes are compatible with mass manufacturing and run at a high yield. The devices show a reliable electrical interconnection between the sensor chip and readout electronics during extended wet operation. Sandwich immunoassays were carried out in the cartridges with surface functionalized sensor chips. Biological response curves were determined for different concentrations of parathyroid hormone (PTH) on the packaged biosensor, which demonstrates the functionality and biocompatibility of the devices. The new packaging concept provides a platform for easy further integration of electrical and fluidic functions, as for instance required for integrated molecular diagnostic devices in cost-effective mass manufacturing

Weak Hard X-Ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-Ray Weakness

DEFF Research Database (Denmark)

Luo, B.; Brandt, W. N.; Alexander, D. M.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than...... expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL...... quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three...

DNA immobilization on polymer-modified Si surface by controlling pH

International Nuclear Information System (INIS)

Demirel, Goekcen Birlik; Caykara, Tuncer

2009-01-01

A novel approach based on polymer-modified Si surface as DNA sensor platforms is presented. The polymer-modified Si surface was prepared by using 3-(methacryloxypropyl)trimethoxysilane [γ-MPS] and poly(acrylamide) [PAAm]. Firstly, a layer of γ-MPS was formed on the hydroxylated silicon surface as a monolayer and then modified with different molecular weight of PAAm to form polymer-modified surface. The polymer-modified Si surface was used for dsDNA immobilization. All steps about formation of layer structure were characterized by ellipsometry, atomic force microscopy (AFM), attenuated total reflectance Fourier transformed infrared (ATR-FTIR), and contact angle (CA) measurements. We found that in this case the amount of dsDNA immobilized onto the surface was dictated by the electrostatic interaction between the substrate surface and the DNA. Our results thus demonstrated that DNA molecules could be immobilized differently onto the polymer-modified support surface via electrostatic interactions.

Microstructure and wear behaviour of silicon doped Cr-N nanocomposite coatings

Energy Technology Data Exchange (ETDEWEB)

Bao Mingdong, E-mail: bmingd@yahoo.com.c [School of mechanical engineering, Ningbo University of Technology, Ningbo 315016 (China); Yu Lei; Xu Xuebo [School of mechanical engineering, Ningbo University of Technology, Ningbo 315016 (China); He Jiawen [State Key Lab. for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an, 710049 (China); Sun Hailin [Teer Coatings Ltd., Berry Hill Industrial Estate, Droitwich Worcestershire WR9 9AS (United Kingdom); Zhejiang Huijin-Teer Coatings Technolgy Co., Ltd., Lin' an 311305 (China); Teer, D.G. [Teer Coatings Ltd., Berry Hill Industrial Estate, Droitwich Worcestershire WR9 9AS (United Kingdom)

2009-07-01

Hard Cr-N and silicon doped Cr-Si-N nanocomposite coatings were deposited using closed unbalanced magnetron sputtering ion plating system. Coatings doped with various Si contents were synthesized by changing the power applied on Si targets. Composition of the films was analyzed using glow discharge optical emission spectrometry (GDOES). Microstructure and properties of the coatings were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and nano-indentation. The harnesses and the elastic modulus of Cr-Si-N coatings gradually increased with rising of silicon content and exhibited a maximum at silicon content of 4.1 at.% and 5.5 at.%. The maximum hardness and elastic modulus of the Cr-Si-N nanocomposite coatings were approximately 30 GPa and 352 GPa, respectively. Further increase in the silicon content resulted in a decrease in the hardness and the elastic modulus of the coatings. Results from XRD analyses of CrN coatings indicated that strongly preferred orientations of (111) were detected. The diffraction patterns of Cr-Si-N coatings showed a clear (220) with weak (200) and (311) preferred orientations, but the peak of CrN (111) was decreased with the increase of Si concentration. The XRD data of single-phase Si{sub 3}N{sub 4} was free of peak. The peaks of CrN (111) and (220) were shifted slightly and broadened with the increase of silicon content. SEM observations of the sections of Cr-Si-N coatings with different silicon concentrations showed a typical columnar structure. It was evident from TEM observation that nanocomposite Cr-Si-N coatings exhibited nano-scale grain size. Friction coefficient and specific wear rate (SWR) of silicon doped Cr-N coatings from pin-on-disk test were significantly lower in comparison to that of CrN coatings.

Learning from Weak and Noisy Labels for Semantic Segmentation

KAUST Repository

Lu, Zhiwu

2016-04-08

A weakly supervised semantic segmentation (WSSS) method aims to learn a segmentation model from weak (image-level) as opposed to strong (pixel-level) labels. By avoiding the tedious pixel-level annotation process, it can exploit the unlimited supply of user-tagged images from media-sharing sites such as Flickr for large scale applications. However, these ‘free’ tags/labels are often noisy and few existing works address the problem of learning with both weak and noisy labels. In this work, we cast the WSSS problem into a label noise reduction problem. Specifically, after segmenting each image into a set of superpixels, the weak and potentially noisy image-level labels are propagated to the superpixel level resulting in highly noisy labels; the key to semantic segmentation is thus to identify and correct the superpixel noisy labels. To this end, a novel L1-optimisation based sparse learning model is formulated to directly and explicitly detect noisy labels. To solve the L1-optimisation problem, we further develop an efficient learning algorithm by introducing an intermediate labelling variable. Extensive experiments on three benchmark datasets show that our method yields state-of-the-art results given noise-free labels, whilst significantly outperforming the existing methods when the weak labels are also noisy.

Learning from Weak and Noisy Labels for Semantic Segmentation

KAUST Repository

Lu, Zhiwu; Fu, Zhenyong; Xiang, Tao; Han, Peng; Wang, Liwei; Gao, Xin

2016-01-01

A weakly supervised semantic segmentation (WSSS) method aims to learn a segmentation model from weak (image-level) as opposed to strong (pixel-level) labels. By avoiding the tedious pixel-level annotation process, it can exploit the unlimited supply of user-tagged images from media-sharing sites such as Flickr for large scale applications. However, these ‘free’ tags/labels are often noisy and few existing works address the problem of learning with both weak and noisy labels. In this work, we cast the WSSS problem into a label noise reduction problem. Specifically, after segmenting each image into a set of superpixels, the weak and potentially noisy image-level labels are propagated to the superpixel level resulting in highly noisy labels; the key to semantic segmentation is thus to identify and correct the superpixel noisy labels. To this end, a novel L1-optimisation based sparse learning model is formulated to directly and explicitly detect noisy labels. To solve the L1-optimisation problem, we further develop an efficient learning algorithm by introducing an intermediate labelling variable. Extensive experiments on three benchmark datasets show that our method yields state-of-the-art results given noise-free labels, whilst significantly outperforming the existing methods when the weak labels are also noisy.

CH-π Interaction Driven Macroscopic Property Transition on Smart Polymer Surface

Science.gov (United States)

Li, Minmin; Qing, Guangyan; Xiong, Yuting; Lai, Yuekun; Sun, Taolei

2015-10-01

Life systems have evolved to utilize weak noncovalent interactions, particularly CH-π interaction, to achieve various biofunctions, for example cellular communication, immune response, and protein folding. However, for artificial materials, it remains a great challenge to recognize such weak interaction, further transform it into tunable macroscopic properties and realize special functions. Here we integrate monosaccharide-based CH-π receptor capable of recognizing aromatic peptides into a smart polymer with three-component “Recognition-Mediating-Function” design, and report the CH-π interaction driven surface property switching on smart polymer film, including wettability, adhesion, viscoelasticity and stiffness. Detailed studies indicate that, the CH-π interaction induces the complexation between saccharide unit and aromatic peptide, which breaks the initial amphiphilic balance of the polymer network, resulting in contraction-swelling conformational transition for polymer chains and subsequent dramatic switching in surface properties. This work not only presents a new approach to control the surface property of materials, but also points to a broader research prospect on CH-π interaction at a macroscopic level.

Efficient and Stable CsPbBr3 Quantum-Dot Powders Passivated and Encapsulated with a Mixed Silicon Nitride and Silicon Oxide Inorganic Polymer Matrix.

Science.gov (United States)

Yoon, Hee Chang; Lee, Soyoung; Song, Jae Kyu; Yang, Heesun; Do, Young Rag

2018-04-11

Despite the excellent optical features of fully inorganic cesium lead halide (CsPbX 3 ) perovskite quantum dots (PeQDs), their unstable nature has limited their use in various optoelectronic devices. To mitigate the instability issues of PeQDs, we demonstrate the roles of dual-silicon nitride and silicon oxide ligands of the polysilazane (PSZ) inorganic polymer to passivate the surface defects and form a barrier layer coated onto green CsPbBr 3 QDs to maintain the high photoluminescence quantum yield (PLQY) and improve the environmental stability. The mixed SiN x /SiN x O y /SiO y passivated and encapsulated CsPbBr 3 /PSZ core/shell composite can be prepared by a simple hydrolysis reaction involving the addition of adding PSZ as a precursor and a slight amount of water into a colloidal CsPbBr 3 QD solution. The degree of the moisture-induced hydrolysis reaction of PSZ can affect the compositional ratio of SiN x , SiN x O y , and SiO y liganded to the surfaces of the CsPbBr 3 QDs to optimize the PLQY and the stability of CsPbBr 3 /PSZ core/shell composite, which shows a high PLQY (∼81.7%) with improved thermal, photo, air, and humidity stability as well under coarse conditions where the performance of CsPbBr 3 QDs typically deteriorate. To evaluate the suitability of the application of the CsPbBr 3 /PSZ powder to down-converted white-light-emitting diodes (DC-WLEDs) as the backlight of a liquid crystal display (LCD), we fabricated an on-package type of tricolor-WLED by mixing the as-synthesized green CsPbBr 3 /PSZ composite powder with red K 2 SiF 6 :Mn 4+ phosphor powder and a poly(methyl methacrylate)-encapsulating binder and coating this mixed paste onto a cup-type blue LED. The fabricated WLED show high luminous efficacy of 138.6 lm/W (EQE = 51.4%) and a wide color gamut of 128% and 111% without and with color filters, respectively, at a correlated color temperature of 6762 K.

High breakdown-strength composites from liquid silicone rubbers

DEFF Research Database (Denmark)

Vudayagiri, Sindhu; Zakaria, Shamsul Bin; Yu, Liyun

2014-01-01

In this paper we investigate the performance of liquid silicone rubbers (LSRs) as dielectric elastomer transducers. Commonly used silicones in this application include room-temperature vulcanisable (RTV) silicone elastomers and composites thereof. Pure LSRs and their composites with commercially...

Influence of hydrogen effusion from hydrogenated silicon nitride layers on the regeneration of boron-oxygen related defects in crystalline silicon

International Nuclear Information System (INIS)

Wilking, S.; Ebert, S.; Herguth, A.; Hahn, G.

2013-01-01

The degradation effect boron doped and oxygen-rich crystalline silicon materials suffer from under illumination can be neutralized in hydrogenated silicon by the application of a regeneration process consisting of a combination of slightly elevated temperature and carrier injection. In this paper, the influence of variations in short high temperature steps on the kinetics of the regeneration process is investigated. It is found that hotter and longer firing steps allowing an effective hydrogenation from a hydrogen-rich silicon nitride passivation layer result in an acceleration of the regeneration process. Additionally, a fast cool down from high temperature to around 550 °C seems to be crucial for a fast regeneration process. It is suggested that high cooling rates suppress hydrogen effusion from the silicon bulk in a temperature range where the hydrogenated passivation layer cannot release hydrogen in considerable amounts. Thus, the hydrogen content of the silicon bulk after the complete high temperature step can be increased resulting in a faster regeneration process. Hence, the data presented here back up the theory that the regeneration process might be a hydrogen passivation of boron-oxygen related defects

Optical temperature sensor with enhanced sensitivity by employing hybrid waveguides in a silicon Mach-Zehnder interferometer

DEFF Research Database (Denmark)

Guan, Xiaowei; Wang, Xiaoyan; Frandsen, Lars Hagedorn

2016-01-01

We report on a novel design of an on-chip optical temperature sensor based on a Mach-Zehnder interferometer configuration where the two arms consist of hybrid waveguides providing opposite temperature-dependent phase changes to enhance the temperature sensitivity of the sensor. The sensitivity...... of the fabricated sensor with silicon/polymer hybrid waveguides is measured to be 172 pm/°C, which is two times larger than a conventional all-silicon optical temperature sensor (∼80 pm/°C). Moreover, a design with silicon/titanium dioxide hybrid waveguides is by calculation expected to have a sensitivity as high...

ULTRATHIN SILICON MEMBRANES TO STUDY SUPERCURRENT TRANSPORT IN CRYSTALLINE SEMICONDUCTORS

NARCIS (Netherlands)

VANHUFFELEN, WM; DEBOER, MJ; KLAPWIJK, TM

1991-01-01

We have developed a two-step anisotropic etching process to fabricate thin silicon membranes, used to study supercurrent transport in semiconductor coupled weak links. The process uses a shallow BF2+ implantation, and permits easy control of membrane thickness less-than-or-equal-to 100 nm.

Highly Porous Silicon Embedded in a Ceramic Matrix: A Stable High-Capacity Electrode for Li-Ion Batteries.

Science.gov (United States)

Vrankovic, Dragoljub; Graczyk-Zajac, Magdalena; Kalcher, Constanze; Rohrer, Jochen; Becker, Malin; Stabler, Christina; Trykowski, Grzegorz; Albe, Karsten; Riedel, Ralf

2017-11-28

We demonstrate a cost-effective synthesis route that provides Si-based anode materials with capacities between 2000 and 3000 mAh·g Si -1 (400 and 600 mAh·g composite -1 ), Coulombic efficiencies above 99.5%, and almost 100% capacity retention over more than 100 cycles. The Si-based composite is prepared from highly porous silicon (obtained by reduction of silica) by encapsulation in an organic carbon and polymer-derived silicon oxycarbide (C/SiOC) matrix. Molecular dynamics simulations show that the highly porous silicon morphology delivers free volume for the accommodation of strain leading to no macroscopic changes during initial Li-Si alloying. In addition, a carbon layer provides an electrical contact, whereas the SiOC matrix significantly diminishes the interface between the electrolyte and the electrode material and thus suppresses the formation of a solid-electrolyte interphase on Si. Electrochemical tests of the micrometer-sized, glass-fiber-derived silicon demonstrate the up-scaling potential of the presented approach.

Effect of pyrolysis atmospheres on the morphology of polymer-derived silicon oxynitrocarbide ceramic films coated aluminum nitride surface and the thermal conductivity of silicone rubber composites

Science.gov (United States)

Chiu, Hsien T.; Sukachonmakul, Tanapon; Wang, Chen H.; Wattanakul, Karnthidaporn; Kuo, Ming T.; Wang, Yu H.

2014-02-01

Amorphous silicon oxycarbide (SiOC) and silicon oxynitrocarbide (SiONC) ceramic films coated aluminum nitride (AlN) were prepared by using preceramic-polysilazane (PSZ) with dip-coating method, followed by pyrolysis at 700 °C in different (air, Ar, N2 and NH3) atmospheres to converted PSZ into SiOCair and SiONC(Ar,N2andNH3) ceramic. The existence of amorphous SiOCair and SiONC(Ar,N2andNH3) ceramic films on AlN surface was characterized by FTIR, XRD and XPS. The interfacial adhesion between silicone rubber and AlN was significantly improved after the introduction of amorphous SiOCair and SiONC(Ar,N2andNH3) ceramic films on AlN surface. It can be observed from AFM that the pyrolysis of PSZ at different atmosphere strongly affected to films morphology on AlN surface as SiOCair and SiONCNH3 ceramic films were more flat and smooth than SiONCN2 and SiONCAr ceramic films. Besides, the enhancement of the thermal conductivity of silicone rubber composites was found to be related to the decrease in the surface roughness of SiOCair and SiONC(Ar,N2andNH3) ceramic films on AlN surface. This present work provided an alternative surface modification of thermally conductive fillers to improve the thermal conductivity of silicon rubber composites by coating with amorphous SiOCair and SiONC(Ar,N2andNH3) ceramic films.

Novel scalable silicone elastomer and poly(2-hydroxyethyl methacrylate) (PHEMA) composite materials for tissue engineering and drug delivery applications

DEFF Research Database (Denmark)

Mohanty, Soumyaranjan; Hemmingsen, Mette; Wojcik, Magdalena

2013-01-01

material with increased hydrophilicity in regard to virgin silicone elastomer, making it suitable as a scaffold for tissue engineering and with the concomitant possibility for delivering drug from the scaffold to the tissue. Interpenetrating polymer networks (IPNs) of silicone elastomer and PHEMA......In recent years hydrogels have received increasing attention as potential materials for applications in regenerative medicine. They can be used for scaffold materials providing structural integrity to tissue constructs, for controlled delivery of drugs and proteins to cell and tissues......, and for support materials in tissue growth. However, the real challenge is to obtain sufficiently good mechanical properties of the hydrogel. The present study shows the combination of two normally non-compatible materials, silicone elastomer and poly(2-hydroxyethyl methacrylate) (PHEMA), into a novel composite...

Omnidirectional Harvesting of Weak Light Using a Graphene Quantum Dot-Modified Organic/Silicon Hybrid Device

KAUST Repository

Tsai, Meng-Lin

2017-04-21

Despite great improvements in traditional inorganic photodetectors and photovoltaics, more progress is needed in the detection/collection of light at low-level conditions. Traditional photodetectors tend to suffer from high noise when operated at room temperature; therefore, these devices require additional cooling systems to detect weak or dim light. Conventional solar cells also face the challenge of poor light-harvesting capabilities in hazy or cloudy weather. The real world features such varying levels of light, which makes it important to develop strategies that allow optical devices to function when conditions are less than optimal. In this work, we report an organic/inorganic hybrid device that consists of graphene quantum dot-modified poly(3,4-ethylenedioxythiophene) polystyrenesulfonate spin-coated on Si for the detection/harvest of weak light. The hybrid configuration provides the device with high responsivity and detectability, omnidirectional light trapping, and fast operation speed. To demonstrate the potential of this hybrid device in real world applications, we measured near-infrared light scattered through human tissue to demonstrate noninvasive oximetric photodetection as well as characterized the device\\'s photovoltaic properties in outdoor (i.e., weather-dependent) and indoor weak light conditions. This organic/inorganic device configuration demonstrates a promising strategy for developing future high-performance low-light compatible photodetectors and photovoltaics.

Visualized Bond Scission in Mechanically Activated Polymers

Institute of Scientific and Technical Information of China (English)

Yuan Yuan; Yu-lan Chen

2017-01-01

Visualization and quantitative evaluation of covalent bond scission in polymeric materials are critical in understanding their failure mechanisms and improving the toughness and reliability of the materials.Mechano-responsive polymers with the ability of molecular-level transduction of force into chromism and luminescence have evoked major interest and experienced significant progress.In the current review,we highlight the recent achievements in covalent mechanochromic and mechanoluminescent polymers,leading to a bridge between macroscopic mechanical properties and microscopic bond scission events.After a general introduction concerning polymer mechanochemistry,various examples that illustrate the strategies of design and incorporation of functional and weak covalent bonds in polymers were presented,the mechanisms underlying the optical phenomenon were introduced and their potential applications as stress sensors were discussed.This review concludes with a comment on the opportunities and challenges of the field.

Transition from weak wave turbulence regime to solitonic regime

Science.gov (United States)

Hassani, Roumaissa; Mordant, Nicolas

2017-11-01

The Weak Turbulence Theory (WTT) is a statistical theory describing the interaction of a large ensemble of random waves characterized by very different length scales. For both weak non-linearity and weak dispersion a different regime is predicted where solitons propagate while keeping their shape unchanged. The question under investigation here is which regime between weak turbulence or soliton gas does the system choose ? We report an experimental investigation of wave turbulence at the surface of finite depth water in the gravity-capillary range. We tune the wave dispersion and the level of nonlinearity by modifying the depth of water and the forcing respectively. We use space-time resolved profilometry to reconstruct the deformed surface of water. When decreasing the water depth, we observe a drastic transition between weak turbulence at the weakest forcing and a solitonic regime at stronger forcing. We characterize the transition between both states by studying their Fourier Spectra. We also study the efficiency of energy transfer in the weak turbulence regime. We report a loss of efficiency of angular transfer as the dispersion of the wave is reduced until the system bifurcates into the solitonic regime. This project has recieved funding from the European Research Council (ERC, Grant Agreement No. 647018-WATU).

Sustainable polymers from renewable resources.

Science.gov (United States)

Zhu, Yunqing; Romain, Charles; Williams, Charlotte K

2016-12-14

Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.

Fabrication of carbon microcapsules containing silicon nanoparticles-carbon nanotubes nanocomposite by sol-gel method for anode in lithium ion battery

International Nuclear Information System (INIS)

Bae, Joonwon

2011-01-01

Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT-C) have been fabricated by a surfactant mediated sol-gel method followed by a carbonization process. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were produced by a wet-type beadsmill method. To obtain Si-CNT nanocomposites with spherical morphologies, a silica precursor (tetraethylorthosilicate, TEOS) and polymer (PMMA) mixture was employed as a structure-directing medium. Thus the Si-CNT/Silica-Polymer microspheres were prepared by an acid catalyzed sol-gel method. Then a carbon precursor such as polypyrrole (PPy) was incorporated onto the surfaces of pre-existing Si-CNT/silica-polymer to generate Si-CNT/Silica-Polymer-PPy microspheres. Subsequent thermal treatment of the precursor followed by wet etching of silica produced Si-CNT-C microcapsules. The intermediate silica/polymer must disappear during the carbonization and etching process resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT-C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT-C microcapsules were measured with a lithium battery half cell tests. - Graphical Abstract: Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT-C) have been fabricated by a surfactant mediated sol-gel method. Highlights: → Polymeric microcapsules containing Si-CNT transformed to carbon microcapsules. → Accommodate volume changes of Si NPs during Li ion charge/discharge. → Sizes of microcapsules were controlled by experimental parameters. �

Controlled Release from Recombinant Polymers

Science.gov (United States)

Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

2014-01-01

Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

Aerosol-assisted extraction of silicon nanoparticles from wafer slicing waste for lithium ion batteries.

Science.gov (United States)

Jang, Hee Dong; Kim, Hyekyoung; Chang, Hankwon; Kim, Jiwoong; Roh, Kee Min; Choi, Ji-Hyuk; Cho, Bong-Gyoo; Park, Eunjun; Kim, Hansu; Luo, Jiayan; Huang, Jiaxing

2015-03-30

A large amount of silicon debris particles are generated during the slicing of silicon ingots into thin wafers for the fabrication of integrated-circuit chips and solar cells. This results in a significant loss of valuable materials at about 40% of the mass of ingots. In addition, a hazardous silicon sludge waste is produced containing largely debris of silicon, and silicon carbide, which is a common cutting material on the slicing saw. Efforts in material recovery from the sludge and recycling have been largely directed towards converting silicon or silicon carbide into other chemicals. Here, we report an aerosol-assisted method to extract silicon nanoparticles from such sludge wastes and their use in lithium ion battery applications. Using an ultrasonic spray-drying method, silicon nanoparticles can be directly recovered from the mixture with high efficiency and high purity for making lithium ion battery anode. The work here demonstrated a relatively low cost approach to turn wafer slicing wastes into much higher value-added materials for energy applications, which also helps to increase the sustainability of semiconductor material and device manufacturing.

The interplay of nanointerface curvature and calcium binding in weak polyelectrolyte-coated nanoparticles.

Science.gov (United States)

Nap, Rikkert J; Gonzalez Solveyra, Estefania; Szleifer, Igal

2018-05-01

When engineering nanomaterials for application in biological systems, it is important to understand how multivalent ions, such as calcium, affect the structural and chemical properties of polymer-modified nanoconstructs. In this work, a recently developed molecular theory was employed to study the effect of surface curvature on the calcium-induced collapse of end-tethered weak polyelectrolytes. In particular, we focused on cylindrical and spherical nanoparticles coated with poly(acrylic acid) in the presence of different amounts of Ca2+ ions. We describe the structural changes that grafted polyelectrolytes undergo as a function of calcium concentration, surface curvature, and morphology. The polymer layers collapse in aqueous solutions that contain sufficient amounts of Ca2+ ions. This collapse, due to the formation of calcium bridges, is not only controlled by the calcium ion concentration but also strongly influenced by the curvature of the tethering surface. The transition from a swollen to a collapsed layer as a function of calcium concentration broadens and shifts to lower amounts of calcium ions as a function of the radius of cylindrical and spherical nanoparticles. The results show how the interplay between calcium binding and surface curvature governs the structural and functional properties of the polymer molecules. This would directly impact the fate of weak polyelectrolyte-coated nanoparticles in biological environments, in which calcium levels are tightly regulated. Understanding such interplay would also contribute to the rational design and optimization of smart interfaces with applications in, e.g., salt-sensitive and ion-responsive materials and devices.

Silicone cushions for engineering applications

International Nuclear Information System (INIS)

Anon.

1984-01-01

When a complex system composed of materials of very different properties is subjected to varying temperature, differential thermal expansion and contraction will produce intolerable stresses unless the parts are separated by suitable cushions. In addition to accommodating differential thermal expansion and contraction, these cushions must absorb shock and vibration, take up dimensional tolerances in the parts, and distribute and attenuate applied loads. We are studying cellular silicone cushions, starting with raw materials and polymer manufacture, to analysis of mechanical and chemical properties, through short- and long-term life testing, in order to tailor cushions to various specific engineering requirements

Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

International Nuclear Information System (INIS)

Norstroem, H.; Blom, H.; Ostling, M.; Nylandsted Larsen, A.; Keinonen, J.; Berg, S.

1991-01-01

For selective etching of SiO 2 on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the 1 H( 15 N,αγ) 12 C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H + ions to pick up an energy equal to the peak-to-peak voltage of the rf signal

Non-classical light emission from single conjugated polymers

Science.gov (United States)

Hollars, Christopher; Lane, Stephen; Huser, Thomas

2002-03-01

Photon-antibunching from single, isolated molecules of collapsed-chain poly[2-methoxy,5-(2’-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been observed using confocal microscopy techniques. Efficient inter-segment energy transfer in collapsed-chain conjugated polymers leads to emission from an average of only 2-3 active sites on a polymer chain that is composed of hundreds of quasi-chromophores. These few centers consist of the segments with the lowest excitation energy and are supplied by the efficient light-harvesting and energy transfer of the surrounding higher-energy segments. This effect depends on the conformation of the polymer molecules, which is controlled by solvent polarity. These results provide new insight into the controversial photophysics of conjugated polymers and their application in optoelectronic devices.

Production of electronic grade lunar silicon by disproportionation of silicon difluoride

Science.gov (United States)

Agosto, William N.

1993-01-01

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Novel polymer composite having diamond particles and boron nitride platelets for thermal management of electric vehicle motors

Science.gov (United States)

Nakajima, Anri; Shoji, Atsushi; Yonemori, Kei; Seo, Nobuhide

2016-02-01

Thermal conductivities of silicone matrix polymers including fillers of diamond particles and/or hexagonal boron nitride (h-BN) platelets were systematically investigated in an attempt to find a thermal interface material (TIM) having high isotropic thermal conductivity and high electrical insulating ability to enable efficient heat dissipation from the motor coil ends of electric vehicles. The TIM with mixed fillers of diamond particles and h-BN platelets had a maximum thermal conductivity of 6.1 W m-1 K-1 that was almost isotropic. This is the highest value among the thermal conductivities of TIMs with silicone matrix polymer reported to date. The mechanism behind the thermal conductivity of the TIMs was also examined from the viewpoint of the change in the number of thermally conductive networks and/or a decrease in the thermal resistivity of junctions of neighboring diamond particles through the incorporation of h-BN platelets. The TIMs developed in this study will make it possible to manage the heat of electric motors and will help to popularize electric vehicles.

Optical properties and ensemble characteristics of size purified Silicon nanocrystals

Science.gov (United States)

Miller, Joseph Bradley

Nanotechnology is at the forefront of current scientific research and nanocrystals are being hailed as the 'artificial' atoms of the 21st century. Semiconducting silicon nanocrystals (SiNCs) are prime candidates for potential commercial applications because of silicon's already ubiquitous presence in the semiconductor industry, nontoxicity and abundance in nature. For realization of these potential applications, the properties and behavior of SiNCs need to be understood and enhanced. In this report, some of the main SiNC synthesis schemes are discussed, including those we are currently experimenting with to create our own SiNCs and the one utilized to create the SiNCs used in this study. The underlying physics that governs the unique behavior of SiNCs is then presented. The properties of the as-produced SiNCs are determined to depend strongly on surface passivation and environment. Size purification, an important aspect of nanomaterial utilization, was successfully performed on our SiNCs though density gradient ultracentrifugation. We demonstrate that the size-purified fractions exhibit an enhanced ability for colloidal self-assembly, with better aligned nanocrystal energy levels which promotes greater photostability in close-packed films and produces a slight increase in photoluminescence (PL) quantum yield. The qualities displayed by the fractions are exploited to form SiNC clusters that exhibit photostable PL. An analysis of SiNC cluster (from individual nanocrystals to collections of more than one thousand) blinking and PL shows an improvement in their PL emitting 'on' times. Pure SiNC films and SiNC-polymer nanocomposites are created and the dependence of their PL on temperature is measured. For such nanocomposites, the coupling between the 'coffee-ring' effect and liquid-liquid phase separation is also examined for ternary mixtures of solvent, polymer and semiconducting nanocrystal. We discover that with the right SiNC-polymer concentration and polymer

Alternative sample-introduction technique to avoid breakthrough in gradient-elution liquid chromatography of polymers

NARCIS (Netherlands)

Reingruber, E.; Bedani, F.; Buchberger, W.; Schoenmakers, P.

2010-01-01

Gradient-elution liquid chromatography (GELC) is a powerful tool for the characterization of synthetic polymers. However, gradient-elution chromatograms often suffer from breakthrough phenomena. Breakthrough can be averted by using a sample solvent as weak as the mobile phase. However, this approach

General approach to polymer chains confined by interacting boundaries.

Science.gov (United States)

Freed, Karl F; Dudowicz, Jacek; Stukalin, Evgeny B; Douglas, Jack F

2010-09-07

Polymer chains, confined to cavities or polymer layers with dimensions less than the chain radius of gyration, appear in many phenomena, such as gel chromatography, rubber elasticity, viscolelasticity of high molar mass polymer melts, the translocation of polymers through nanopores and nanotubes, polymer adsorption, etc. Thus, the description of how the constraints alter polymer thermodynamic properties is a recurrent theoretical problem. A realistic treatment requires the incorporation of impenetrable interacting (attractive or repulsive) boundaries, a process that introduces significant mathematical complications. The standard approach involves developing the generalized diffusion equation description of the interaction of flexible polymers with impenetrable confining surfaces into a discrete eigenfunction expansion, where the solutions are normally truncated at the first mode (the "ground state dominance" approximation). This approximation is mathematically well justified under conditions of strong confinement, i.e., a confinement length scale much smaller than the chain radius of gyration, but becomes unreliable when the polymers are confined to dimensions comparable to their typically nanoscale size. We extend a general approach to describe polymers under conditions of weak to moderate confinement and apply this semianalytic method specifically to determine the thermodynamics and static structure factor for a flexible polymer confined between impenetrable interacting parallel plate boundaries. The method is first illustrated by analyzing chain partitioning between a pore and a large external reservoir, a model system with application to chromatography. Improved agreement is found for the partition coefficients of a polymer chain in the pore geometry. An expression is derived for the structure factor S(k) in a slit geometry to assist in more accurately estimating chain dimensions from scattering measurements for thin polymer films.

Porous Silicon Structures as Optical Gas Sensors

Directory of Open Access Journals (Sweden)

Igor A. Levitsky

2015-08-01

Full Text Available We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

Polymer filters for ultraviolet-excited integrated fluorescence sensing

International Nuclear Information System (INIS)

Dandin, Marc; Abshire, Pamela; Smela, Elisabeth

2012-01-01

Optical filters for blocking ultraviolet (UV) light were fabricated by doping various polymer hosts with a UV absorbing chromophore. The polymers were polydimethylsiloxane (PDMS), a silicone elastomer frequently used in microfluidics, SU-8, a photopatternable epoxy, and Humiseal 1B66, an acrylic coating used for moisture protection of integrated circuits. The chromophore was 2-(2′-hydroxy-5′-methylphenyl) benzotriazole (BTA), which has a high extinction coefficient between 300 nm and 400 nm. We demonstrate filters 5 µm thick that exhibit high ultraviolet rejection (nearly −40 dB at 342 nm) yet pass visible light (near 0 dB above 400 nm), making them ideal for ultraviolet-excited fluorescence sensing within microsystems. The absorbance of the BTA depended on the host polymer. These filters are promising for integrated fluorescence spectroscopy in bioanalytical platforms because they can be patterned by dry etching, molding or exposure to ultraviolet light. (paper)

Polymer-Based Surfaces Designed to Reduce Biofilm Formation: From Antimicrobial Polymers to Strategies for Long-Term Applications.

Science.gov (United States)

Riga, Esther K; Vöhringer, Maria; Widyaya, Vania Tanda; Lienkamp, Karen

2017-10-01

Contact-active antimicrobial polymer surfaces bear cationic charges and kill or deactivate bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). The exact mechanism of this interaction is still under debate. While cationic antimicrobial polymer surfaces can be very useful for short-term applications, they lose their activity once they are contaminated by a sufficiently thick layer of adhering biomolecules or bacterial cell debris. This layer shields incoming bacteria from the antimicrobially active cationic surface moieties. Besides discussing antimicrobial surfaces, this feature article focuses on recent strategies that were developed to overcome the contamination problem. This includes bifunctional materials with simultaneously presented antimicrobial and protein-repellent moieties; polymer surfaces that can be switched from an antimicrobial, cell-attractive to a cell-repellent state; polymer surfaces that can be regenerated by enzyme action; degradable antimicrobial polymers; and antimicrobial polymer surfaces with removable top layers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Resonant tunnelling from nanometre-scale silicon field emission cathodes

International Nuclear Information System (INIS)

Johnson, S.; Markwitz, A.

2005-01-01

In this paper we report the field emission properties of self-assembled silicon nanostructures formed on an n-type silicon (100) substrate by electron beam annealing. The nanostructures are square based, with an average height of 8 nm and are distributed randomly over the entire substrate surface. Following conditioning, the silicon nanostructure field emission characteristics become stable and reproducible with electron emission occurring for fields as low as 3 Vμm-1. At higher fields, a superimposed on a background current well described by conventional Fowler-Nordheim theory. These current peaks are understood to result from enhanced tunnelling through resonant states formed at the substrate-nanostructure and nanostructure-vacuum interface. (author). 13 refs., 3 figs

Optimal Control of Polymer Flooding Based on Maximum Principle

Directory of Open Access Journals (Sweden)

Yang Lei

2012-01-01

Full Text Available Polymer flooding is one of the most important technologies for enhanced oil recovery (EOR. In this paper, an optimal control model of distributed parameter systems (DPSs for polymer injection strategies is established, which involves the performance index as maximum of the profit, the governing equations as the fluid flow equations of polymer flooding, and the inequality constraint as the polymer concentration limitation. To cope with the optimal control problem (OCP of this DPS, the necessary conditions for optimality are obtained through application of the calculus of variations and Pontryagin’s weak maximum principle. A gradient method is proposed for the computation of optimal injection strategies. The numerical results of an example illustrate the effectiveness of the proposed method.

Behavior of adhesion forces of silicone adhesive sealants and mastic butyl under the influence of ionizing radiation

International Nuclear Information System (INIS)

Costa, Wanderley da

2012-01-01

Adhesives are products that can keep materials together by bonds between the surfaces. Sealants are products that can keep filled a space between two surfaces, through a barrier that is configured as a 'bridge' between the two surfaces. The mastic is a product made of a mixture of substances with the primary butyl polymer, with the consistency of a mass not dried that can be used as a sealant. The polysiloxane, also known as silicone are the most important synthetic polymers with inorganic structure, and are matrices of silicone adhesive sealants. To demonstrate the behavior of the adhesive forces of these products under different conditions, we used five different techniques. These products were subjected to two different conditions to verify the behavior of adhesion, one at the environmental condition and another under the ionizing radiation. The results showed not only differences between products (silicone and mastic), but also that the adhesive forces have different behaviors under the conditions which the samples were subjected. With this was reached the goal of this study that aspired show the differences between the mastic and silicone, this last one is often considered - erroneously - the same as mastic. Thus it was proven that: 1. silicone can be regarded as an adhesive and a sealant at ambient conditions, 2. mastic improves substantially adhesion in an environment of ionizing radiation and this property can be an excellent alternative to the adhesive market. (author)

Dissipative weak solutions to compressible Navier–Stokes–Fokker–Planck systems with variable viscosity coefficients

Czech Academy of Sciences Publication Activity Database

Feireisl, Eduard; Lu, Y.; Süli, E.

2016-01-01

Roč. 443, č. 1 (2016), s. 322-351 ISSN 0022-247X Keywords : weak solutions * kinetic polymer models * FENE chain Subject RIV: BA - General Mathematics Impact factor: 1.064, year: 2016 http://www.sciencedirect.com/science/article/pii/S0022247X1630172X

The modification of nanocomposite hybrid polymer surfaces by exposure to oxygen containing plasmas

Science.gov (United States)

Figueiredo, Ashley; Zimmermann, Katherine; Augustine, Brian; Hughes, Chris; Chusuei, Charles

2006-11-01

The wetting properties of the surfaces of the nanocomposite hybrid polymer poly[(propylmethacryl-heptaisobutyl- polyhedral oligomeric silsequioxane)-co-(methylmethacrylate)] (POSS-PMMA)has been studied before and after exposure to plasmas containing oxygen. The contact angle of water droplets on the surface showed a substantial decrease after plasma exposure indicating an increase in the hydrophilicity of the surface. A model was developed in which the plasma preferentially removed organic material including both the PMMA backbone and isobutyl groups from the corners of the POSS cages leaving behind a surface characterized by the silicon oxide-like POSS material. Measurements of surface concentrations of oxygen, silicon, and carbon by x-ray photoelectron spectroscopy (XPS) showed an increase in the amount of oxygen and silicon compared to carbon and the appropriate chemical shifts were observed in the XPS data to support the model of Si-O enrichment on the surface. Variable angle spectroscopic ellipsometry (VASE) and atomic force microscopy (AFM) measurements also supported the model and these results will be presented.

USE OF POLYMERS TO RECOVER VISCOUS OIL FROM UNCONVENTIONAL RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Randall Seright

2011-09-30

This final technical progress report summarizes work performed the project, 'Use of Polymers to Recover Viscous Oil from Unconventional Reservoirs.' The objective of this three-year research project was to develop methods using water soluble polymers to recover viscous oil from unconventional reservoirs (i.e., on Alaska's North Slope). The project had three technical tasks. First, limits were re-examined and redefined for where polymer flooding technology can be applied with respect to unfavorable displacements. Second, we tested existing and new polymers for effective polymer flooding of viscous oil, and we tested newly proposed mechanisms for oil displacement by polymer solutions. Third, we examined novel methods of using polymer gels to improve sweep efficiency during recovery of unconventional viscous oil. This report details work performed during the project. First, using fractional flow calculations, we examined the potential of polymer flooding for recovering viscous oils when the polymer is able to reduce the residual oil saturation to a value less than that of a waterflood. Second, we extensively investigated the rheology in porous media for a new hydrophobic associative polymer. Third, using simulation and analytical studies, we compared oil recovery efficiency for polymer flooding versus in-depth profile modification (i.e., 'Bright Water') as a function of (1) permeability contrast, (2) relative zone thickness, (3) oil viscosity, (4) polymer solution viscosity, (5) polymer or blocking-agent bank size, and (6) relative costs for polymer versus blocking agent. Fourth, we experimentally established how much polymer flooding can reduce the residual oil saturation in an oil-wet core that is saturated with viscous North Slope crude. Finally, an experimental study compared mechanical degradation of an associative polymer with that of a partially hydrolyzed polyacrylamide. Detailed results from the first two years of the project may be

Fabrication of carbon microcapsules containing silicon nanoparticles-carbon nanotubes nanocomposite by sol-gel method for anode in lithium ion battery

Science.gov (United States)

Bae, Joonwon

2011-07-01

Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT@C) have been fabricated by a surfactant mediated sol-gel method followed by a carbonization process. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were produced by a wet-type beadsmill method. To obtain Si-CNT nanocomposites with spherical morphologies, a silica precursor (tetraethylorthosilicate, TEOS) and polymer (PMMA) mixture was employed as a structure-directing medium. Thus the Si-CNT/Silica-Polymer microspheres were prepared by an acid catalyzed sol-gel method. Then a carbon precursor such as polypyrrole (PPy) was incorporated onto the surfaces of pre-existing Si-CNT/silica-polymer to generate Si-CNT/Silica-Polymer@PPy microspheres. Subsequent thermal treatment of the precursor followed by wet etching of silica produced Si-CNT@C microcapsules. The intermediate silica/polymer must disappear during the carbonization and etching process resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT@C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT@C microcapsules were measured with a lithium battery half cell tests.

Double stabilization of nanocrystalline silicon: a bonus from solvent

Energy Technology Data Exchange (ETDEWEB)

Kolyagin, Y. G.; Zakharov, V. N.; Yatsenko, A. V.; Paseshnichenko, K. A.; Savilov, S. V.; Aslanov, L. A., E-mail: aslanov.38@mail.ru [Lomonosov Moscow State University (Russian Federation)

2016-01-15

Double stabilization of the silicon nanocrystals was observed for the first time by {sup 29}Si and {sup 13}C MAS NMR spectroscopy. The role of solvent, 1,2-dimethoxyethane (glyme), in formation and stabilization of silicon nanocrystals as well as mechanism of modification of the surface of silicon nanocrystals by nitrogen-heterocyclic carbene (NHC) was studied in this research. It was shown that silicon nanocrystals were stabilized by the products of cleavage of the C–O bonds in ethers and similar compounds. The fact of stabilization of silicon nanoparticles with NHC ligands in glyme was experimentally detected. It was demonstrated that MAS NMR spectroscopy is rather informative for study of the surface of silicon nanoparticles but it needs very pure samples.

Silicon epitaxy on textured double layer porous silicon by LPCVD

International Nuclear Information System (INIS)

Cai Hong; Shen Honglie; Zhang Lei; Huang Haibin; Lu Linfeng; Tang Zhengxia; Shen Jiancang

2010-01-01

Epitaxial silicon thin film on textured double layer porous silicon (DLPS) was demonstrated. The textured DLPS was formed by electrochemical etching using two different current densities on the silicon wafer that are randomly textured with upright pyramids. Silicon thin films were then grown on the annealed DLPS, using low-pressure chemical vapor deposition (LPCVD). The reflectance of the DLPS and the grown silicon thin films were studied by a spectrophotometer. The crystallinity and topography of the grown silicon thin films were studied by Raman spectroscopy and SEM. The reflectance results show that the reflectance of the silicon wafer decreases from 24.7% to 11.7% after texturing, and after the deposition of silicon thin film the surface reflectance is about 13.8%. SEM images show that the epitaxial silicon film on textured DLPS exhibits random pyramids. The Raman spectrum peaks near 521 cm -1 have a width of 7.8 cm -1 , which reveals the high crystalline quality of the silicon epitaxy.

Experimental study of the retention properties of a cyclo olefin polymer pillar array column in reversed-phase mode.

Science.gov (United States)

Illa, Xavi; De Malsche, Wim; Gardeniers, Han; Desmet, Gert; Romano-Rodríguez, Albert

2010-11-01

Experimental measurements to study the retention capacity and band broadening under retentive conditions using micromachined non-porous pillar array columns fabricated in cyclo olefin polymer are presented. In particular, three columns with different depths but with the same pillar structure have been fabricated via hot embossing and pressure-assisted thermal bonding. Separations of a mixture of four coumarins using varying mobile phase compositions have been monitored to study the relation between the retention factor and the ratio of organic solvent in the aqueous mobile phase. Moreover, the linear relation between the retention and the surface/volume ratio predicted in theory has been observed, achieving retention factors up to k=2.5. Under the same retentive conditions, minimal reduced plate height values of h(min)=0.4 have been obtained at retention factors of k=1.2. These experimental results are compared with the case of non-porous and porous silicon pillars. Similar results for the plate heights are achieved while retention factors are higher than the non-porous silicon column and considerably smaller than the porous pillar column, given the non-porous nature of the used cyclo olefin polymer. The feasibility of using this polymer column as an alternative to the pillar array silicon columns is corroborated.

Strong Selective Adsorption of Polymers.

Science.gov (United States)

Ge, Ting; Rubinstein, Michael

2015-06-09

A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker polymers strongly overlap. We anticipate the formation of a self-similar carpet and with increasing l / d a two-layer structure with a brush of loops covered by a self-similar carpet. As l / d exceeds the

Process for making silicon from halosilanes and halosilicons

Science.gov (United States)

Levin, Harry (Inventor)

1988-01-01

A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

Effect of acid leaching conditions on impurity removal from silicon doped by magnesium

Directory of Open Access Journals (Sweden)

Stine Espelien

2017-07-01

Full Text Available The effect of magnesium addition into a commercial silicon and its leaching refining behavior is studied for producing solar grade silicon feedstock. Two different levels of Mg is added into a commercial silicon and the leaching of the produced alloys by 10% HCl solution at 60 ℃ for different durations is performed. It is shown that the microstructure of the alloy and in particular the distribution of eutectic phases is dependent on the amount of the added Mg. Moreover, the metallic impurities in silicon such as Fe, Al, Ca and Ti are mainly forming silicide particles with different compositions. These silicides are physically more detached from the primary silicon grains and their removal through chemical and physical separation in leaching is better for higher Mg additions. It is observed that the leaching is more effective for the purification of smaller silicon particles produced from each Mg-doped silicon alloy. It is shown that acid leaching by the applied method is effective to reach more than 70% of phosphorous removal. It is also shown that the purity of silicon is dependent on the total Mg removal and effectiveness of leaching on removing the Mg2Si phase.

Nature of the Binding Interactions between Conjugated Polymer Chains and Fullerenes in Bulk Heterojunction Organic Solar Cells

KAUST Repository

Ravva, Mahesh Kumar; Wang, Tonghui; Bredas, Jean-Luc

2016-01-01

Blends of π-conjugated polymers and fullerene derivatives are ubiquitous as the active layers of organic solar cells. However, a detailed understanding of the weak noncovalent interactions at the molecular level between the polymer chains

SOI silicon on glass for optical MEMS

DEFF Research Database (Denmark)

Larsen, Kristian Pontoppidan; Ravnkilde, Jan Tue; Hansen, Ole

2003-01-01

and a final sealing at the interconnects can be performed using a suitable polymer. Packaged MEMS on glass are advantageous within Optical MEMS and for sensitive capacitive devices. We report on experiences with bonding SOI to Pyrex. Uniform DRIE shallow and deep etching was achieved by a combination......A newly developed fabrication method for fabrication of single crystalline Si (SCS) components on glass, utilizing Deep Reactive Ion Etching (DRIE) of a Silicon On Insulator (SOI) wafer is presented. The devices are packaged at wafer level in a glass-silicon-glass (GSG) stack by anodic bonding...... of an optimized device layout and an optimized process recipe. The behavior of the buried oxide membrane when used as an etch stop for the through-hole etch is described. No harmful buckling or fracture of the membrane is observed for an oxide thickness below 1 μm, but larger and more fragile released structures...

III-V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration

Science.gov (United States)

Cariou, Romain; Benick, Jan; Feldmann, Frank; Höhn, Oliver; Hauser, Hubert; Beutel, Paul; Razek, Nasser; Wimplinger, Markus; Bläsi, Benedikt; Lackner, David; Hermle, Martin; Siefer, Gerald; Glunz, Stefan W.; Bett, Andreas W.; Dimroth, Frank

2018-04-01

Silicon dominates the photovoltaic industry but the conversion efficiency of silicon single-junction solar cells is intrinsically constrained to 29.4%, and practically limited to around 27%. It is possible to overcome this limit by combining silicon with high-bandgap materials, such as III-V semiconductors, in a multi-junction device. Significant challenges associated with this material combination have hindered the development of highly efficient III-V/Si solar cells. Here, we demonstrate a III-V/Si cell reaching similar performances to standard III-V/Ge triple-junction solar cells. This device is fabricated using wafer bonding to permanently join a GaInP/GaAs top cell with a silicon bottom cell. The key issues of III-V/Si interface recombination and silicon's weak absorption are addressed using poly-silicon/SiOx passivating contacts and a novel rear-side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a two-terminal GaInP/GaAs//Si solar cell reaching a 1-sun AM1.5G conversion efficiency of 33.3%.

A Study on the Thermomechanical Reliability Risks of Through-Silicon-Vias in Sensor Applications

Directory of Open Access Journals (Sweden)

Shuai Shao

2017-02-01

Full Text Available Reliability risks for two different types of through-silicon-vias (TSVs are discussed in this paper. The first is a partially-filled copper TSV, if which the copper layer covers the side walls and bottom. A polymer is used to fill the rest of the cavity. Stresses in risk sites are studied and ranked for this TSV structure by FEA modeling. Parametric studies for material properties (modulus and thermal expansion of TSV polymer are performed. The second type is a high aspect ratio TSV filled by polycrystalline silicon (poly Si. Potential risks of the voids in the poly Si due to filling defects are studied. Fracture mechanics methods are utilized to evaluate the risk for two different assembly conditions: package assembled to printed circuit board (PCB and package assembled to flexible substrate. The effect of board/substrate/die thickness and the size and location of the void are discussed.

A study of luminescence from silicon-rich silica fabricated by plasma enhanced chemical vapour deposition

International Nuclear Information System (INIS)

Trwoga, P.F.

1998-01-01

Silicon is the most studied electronic material known to man and dominates the electronics industry in its use as a semiconductors for nearly all integrated electronics. However, optoelectronics is almost entirely based on III-V materials. This technology is used because silicon is a very inefficient light source, whereas the III-V band structure can lend itself to efficient light emission by electron injection. However, due to the overwhelming dominance of silicon based electronics it is still a highly desirable goal to generate light efficiently from silicon based materials. Recently, studies have demonstrated that efficient visible luminescence can be obtained from certain novel forms of silicon. These materials include porous silicon, hydrogenated amorphous silicon, and silicon-rich silica (SiO x x x is studied in detail; in addition, electroluminescence and rare-earth doping of silicon-rich silica is also addressed. (author)

Development directions of packaging made from polymer materials

Directory of Open Access Journals (Sweden)

Jovanović Slobodan

2011-01-01

Full Text Available World packaging market achieves turnover of about $620 billion per year with one third of this amount being associated to packaging made from polymer materials. It is expected that this kind of packaging consumption will hold at least 3% of world packaging market share in the next five years and that it will surpass the consumption of all other materials used in the packaging production. This can be contributed to product quality, low production costs as well as significant investments made in the development of polymer materials, packaging technology and packaging. This paper presents some development directions for packaging made from polymer materials, such as: packaging in the protective atmosphere, the use of active and intelligent packaging, and the use of biopolymers and recycled polymers for packaging production that come into direct contact with the packed product.

Beam Simulation Studies of Plasma-Surface Interactions in Fluorocarbon Etching of Silicon and Silicon Dioxide

Science.gov (United States)

Gray, David C.

1992-01-01

A molecular beam apparatus has been constructed which allows the synthesis of dominant species fluxes to a wafer surface during fluorocarbon plasma etching. These species include atomic F as the primary etchant, CF _2 as a potential polymer forming precursor, and Ar^{+} or CF _{rm x}^{+} type ions. Ionic and neutral fluxes employed are within an order of magnitude of those typical of fluorocarbon plasmas and are well characterized through the use of in -situ probes. Etching yields and product distributions have been measured through the use of in-situ laser interferometry and line-of-sight mass spectrometry. XPS studies of etched surfaces were performed to assess surface chemical bonding states and average surface stoichiometry. A useful design guide was developed which allows optimal design of straight -tube molecular beam dosers in the collisionally-opaque regime. Ion-enhanced surface reaction kinetics have been studied as a function of the independently variable fluxes of free radicals and ions, as well as ion energy and substrate temperature. We have investigated the role of Ar ^{+} ions in enhancing the chemistries of F and CF_2 separately, and in combination on undoped silicon and silicon dioxide surfaces. We have employed both reactive and inert ions in the energy range most relevant to plasma etching processes, 20-500 eV, through the use of Kaufman and ECR type ion sources. The effect of increasing ion energy on the etching of fluorine saturated silicon and silicon dioxide surfaces was quantified through extensions of available low energy physical sputtering theory. Simple "site"-occupation models were developed for the quantification of the ion-enhanced fluorine etching kinetics in these systems. These models are suitable for use in topography evolution simulators (e.g. SAMPLE) for the predictive modeling of profile evolution in non-depositing fluorine-based plasmas such as NF_3 and SF_6. (Copies available exclusively from MIT Libraries, Rm. 14

Microparticles based on natural and synthetic polymers for ophthalmic applications.

Science.gov (United States)

Tataru, G; Popa, M; Costin, D; Desbrieres, J

2012-05-01

Sodium salt of carboxymethylcellulose/poly(vinyl alcohol) particles suitable for application in ocular drug administration were prepared by crosslinking with epichlorohydrin in an alkaline medium, in reverse emulsion. The influence of parameters related with the particles elaboration process (ratio between polymer mixture and crosslinking agent, concentration of polymer solution, duration of crosslinking reaction, stirring intensity, etc.) based on their composition, size, and swelling ability was studied. Obtained microparticles fulfill the requirements for biomaterials-they are formed from biocompatible polymers; the acute toxicity value (LD(50)) is high enough to consider these materials as weakly toxic (hence able to introduce within the organism); they are able to include and release drugs in a controlled way. The in vivo adrenalin ocular delivery from the microparticles was tested on voluntary human patient. The particles showed good adhesion properties without irritation to the patient and proved the capability to treat the ocular congestion. Copyright © 2012 Wiley Periodicals, Inc.

Temperature responsive porous silicon nanoparticles for cancer therapy - spatiotemporal triggering through infrared and radiofrequency electromagnetic heating.

Science.gov (United States)

Tamarov, Konstantin; Xu, Wujun; Osminkina, Liubov; Zinovyev, Sergey; Soininen, Pasi; Kudryavtsev, Andrey; Gongalsky, Maxim; Gaydarova, Azha; Närvänen, Ale; Timoshenko, Victor; Lehto, Vesa-Pekka

2016-11-10

One critical functionality of the carrier system utilized in targeted drug delivery is its ability to trigger the release of the therapeutic cargo once the carrier has reached its target. External triggering is an alluring approach as it can be applied in a precise spatiotemporal manner. In the present study, we achieved external triggering through the porous silicon (PSi) nanoparticles (NPs) by providing a pulse of infrared or radiofrequency radiation. The NPs were grafted with a temperature responsive polymer whose critical temperature was tailored to be slightly above 37°C. The polymer coating improved the biocompatibility of the NPs significantly in comparison with their uncoated counterparts. Radiation induced a rapid temperature rise, which resulted in the collapse of the polymer chains facilitating the cargo release. Both infrared and radiofrequency radiation were able to efficiently trigger the release of the encapsulated drug in vitro and induce significant cell death in comparison to the control groups. Radiofrequency radiation was found to be more efficient in vitro, and the treatment efficacy was verified in vivo in a lung carcinoma (3LL) mice model. After a single intratumoral administration of the carrier system combined with radiofrequency radiation, there was clear suppression of the growth of the carcinoma and a prolongation of the survival time of the animals. The temperature responsive (TR) polymer grafted on the surface of porous silicon nanoparticles (PSi NPs) changes its conformation in response to the heating induced by infrared or radiofrequency radiation. The conformation change allows the loaded doxorubicin to escape from the pores, achieving controlled drug release from TR PSi NPs, which displayed efficacy against malignant cells both in vitro and in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

NARCIS (Netherlands)

Rosenauer, M.; Buchegger, W.; Finoulst, I.; Verhaert, P.D.E.M.; Vellekoop, M.

2010-01-01

In this study, the design, realization and measurement results of a novel optofluidic system capable of performing absorbance-based flow cytometric analysis is presented. This miniaturized laboratory platform, fabricated using SU-8 on a silicon substrate, comprises integrated polymer-based

A novel approach in preparing polymer/nano-CaCO3 composites

Institute of Scientific and Technical Information of China (English)

Zhengying LIU; Runze YU; Mingbo YANG; Jianmin FENG; Wei YANG; Bo YIN

2008-01-01

An novel compounding process using nano-CaCO3 aqueous suspension for preparing polymer/ nano-CaCO3 composites with nanoparticles dispersed at the nanoscale is reported. The process is called the mild mixing method. In this method, the pre-dispersed nano-particle suspensions are blended with melting polymers in a weak shearing field using an extruder, followed by removing the water from the vent. The four typical poly-meric nanocomposites were prepared by mild mixing method. The dispersion of nano-CaCO3 in the matrix of the polymer at the nanoscale was confirmed by scanning electron microscopy (SEM). The molecular weights of polycarbonate (PC) and its nanocomposite showed that the degradation had not occurred during the mild mixing processing. The mechanical properties of the composite with 1.5 wt-% nano-CaCO3 improve slightly. It proved that this approach is suitable for the preparation of nano-composites based on both polar and non-polar polymers.

FY 1997 R/D project of industrial and scientific technologies contracted with NEDO. Report on R/D of organosilicon polymers; 1997 nendo sangyo kagaku gijutsu kenkyu kaihatsu jigyo Shin energy Sangyo Gijutsu Sogo Kaihatsu Kiko itaku. Keisokei kobunshi zairyo no kenkyu kaihatsu (keisokei kobunshi zairyo no kenkyu kaihatsu) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

The purpose of this study is to establish fundamental techniques for molecular design, synthesis, material processing and evaluation of organosilicon polymers having excellent electro- and photo-functions, and advanced heat-proof, fire-proof and mechanical properties. This R/D includes (1) R/D of electrical conducting materials by organosilicon polymers, (2) R/D of novel organosilicon polymers applicable to direct lithography, (3) R/D of new silicon-based polymer materials with electro-luminous function, and (4) R/D of silicon-based polymers for new photoconductive materials. In (1), synthesis method of regular polymers with a 3-D structure was developed. Non-volatile dopants were developed, and structures of polymer-dopant composites could be controlled. In (2), precise control of conductivity was examined. Material processing and evaluation techniques were also examined through stabilization of polysilane thin films, optimization of pattern forming conditions, and precision of patterns. In (3), new silicon-based polymers have been synthesized. In (4), two kinds of polymers have been synthesized for development of materials with high photo-carrier generation efficiency and high mobility. 72 refs., 71 figs., 22 tabs.

Some fundamental and applicative properties of [polymer/nano-SiC] hybrid nanocomposites

International Nuclear Information System (INIS)

Kassiba, A; Boucle, J; Makowska-Janusik, M; Errien, N

2007-01-01

Hybrid nanocomposites which combine polymer as host matrix and nanocrystals as active elements are promising functional materials for electronics, optics or photonics. In these systems, the physical response is governed by the nanocrystal features (size, surface and defect states), the polymer properties and the polymer-nanocrystal interface. This work reviews some selective nanostructured architectures based on active elements such as silicon carbide (SiC) nanocrystals and polymer host matrices. Beyond an overview of some key properties of the nanocrystals, a main part will be devoted to the electro-optical (EO) properties of SiC based hybrid systems where SiC nanocrystals are embedded in polymer matrices of different chemical nature such as poly-(methylmethacrylate) (PMMA), poly-vinylcarbazole (PVK) or polycarbonate. Using this approach, the organic-inorganic interface effects are emphasised with regard to the dielectric or hole transporting behaviour of PMMA and PVK respectively. These effects are illustrated through different EO responses associated with hybrid composites based on PMMA or PVK

Some fundamental and applicative properties of [polymer/nano-SiC] hybrid nanocomposites

Science.gov (United States)

Kassiba, A.; Bouclé, J.; Makowska-Janusik, M.; Errien, N.

2007-08-01

Hybrid nanocomposites which combine polymer as host matrix and nanocrystals as active elements are promising functional materials for electronics, optics or photonics. In these systems, the physical response is governed by the nanocrystal features (size, surface and defect states), the polymer properties and the polymer-nanocrystal interface. This work reviews some selective nanostructured architectures based on active elements such as silicon carbide (SiC) nanocrystals and polymer host matrices. Beyond an overview of some key properties of the nanocrystals, a main part will be devoted to the electro-optical (EO) properties of SiC based hybrid systems where SiC nanocrystals are embedded in polymer matrices of different chemical nature such as poly-(methylmethacrylate) (PMMA), poly-vinylcarbazole (PVK) or polycarbonate. Using this approach, the organic-inorganic interface effects are emphasised with regard to the dielectric or hole transporting behaviour of PMMA and PVK respectively. These effects are illustrated through different EO responses associated with hybrid composites based on PMMA or PVK.

Interfacial Friction and Adhesion of Polymer Brushes

KAUST Repository

Landherr, Lucas J. T.

2011-08-02

A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

Science.gov (United States)

Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

2013-07-01

Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.

Functional Nanoporous Polymers from Block Copolymer Precursors

DEFF Research Database (Denmark)

Guo, Fengxiao

Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed......, where living anionic polymerization and atom transfer radical polymerization (ATRP) are combined to synthesize a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer precursor. By using either anhydrous hydrogen fluoride or trifluoroacetic acid, PtBA block...

Novel method of separating macroporous arrays from p-type silicon substrate

International Nuclear Information System (INIS)

Peng Bobo; Wang Fei; Liu Tao; Yang Zhenya; Wang Lianwei; Fu, Ricky K. Y.; Chu, Paul K.

2012-01-01

This paper presents a novel method to fabricate separated macroporous silicon using a single step of photo-assisted electrochemical etching. The method is applied to fabricate silicon microchannel plates in 100 mm p-type silicon wafers, which can be used as electron multipliers and three-dimensional Li-ion microbatteries. Increasing the backside illumination intensity and decreasing the bias simultaneously can generate additional holes during the electrochemical etching which will create lateral etching at the pore tips. In this way the silicon microchannel can be separated from the substrate when the desired depth is reached, then it can be cut into the desired shape by using a laser cutting machine. Also, the mechanism of lateral etching is proposed. (semiconductor materials)

Synthesis of Si epitaxial layers from technical silicon by liquid-phase epitaxy method

International Nuclear Information System (INIS)

Ibragimov, Sh.I.; Saidov, A.S.; Sapaev, B.; Horvat, M.A.

2004-01-01

Full text: For today silicon is one of the most suitable materials because it is investigated, cheap and several its parameters are even just as good as those of connections A III B V . Disintegration of the USSR has led to the must difficult position of the industry of silicon instrument manufacture because of all industry of semiconductor silicon manufacture had generally concentrated in Ukraine. The importance of semiconductor silicon is rather great, because of, in opinion of expects, the nearest decade this material will dominate over not only on microelectronics but also in the majority of basic researches. Research of obtain of semiconductor silicon, power electronics and solar conversion, is topical interest of the science. In the work research of technological conditions of obtain and measurement of parameters of epitaxial layers obtained from technical silicon + stannum is resulted. Growth of silicon epitaxial layer with suitable parameters on thickness, cleanliness uniformity and structural perfection depends on the correct choice of condition of the growth and temperature. It is shown that in this case the growth occurring without preliminary clearing of materials (mix materials and substrates) at crystallization of epitaxial layer from technical silicon is accompanied by clearing of silicon film from majority of impurities order-of-magnitude. As starting raw material technical silicon of mark Kr.3 has been taken. By means of X-ray microanalyzer 'Jeol' JSM 5910 LV - Japan the quantitative analysis from the different points has been and from the different sides and from different points has been carried out. After corresponding chemical and mechanical processing the quantitative analysis of layer on chip has been carried out. Results of the quantitative analysis are shown. More effective clearing occurs that of the impurity atoms such as Al, P, Ca, Ti and Fe. The obtained material (epitaxial layer) has the parameters: specific resistance ρ∼0.1-4.0 �

Brownian dynamics simulation of a polymer chain in a solid-state nanopore attached to a molecular stop

Science.gov (United States)

Wells, Craig; Hulings, Zachery; Melnikov, Dmitriy; Gracheva, Maria

We study a nanopore inside a silicon dioxide membrane submerged in a KCl solution with a negatively charged polymer chain of varying lengths whose movement is described using Brownian dynamics. The polymer is attached to a molecule with a radius larger than that of the nanopore's which acts as a molecular stop, allowing the chain to thread the nanopore but preventing it from translocating. We found that the polymer chain's variation of movement along the nanopore decreased when increasing applied biases and chain lengths for portions of the chain closest to the molecular stop. The chain displacement within the pore is also compared to a freely translocating polymer where preliminary results show the free polymer having a greater variation in the radial direction. Overall, our preliminary results indicate that the radial direction of the polymer chain is dominated by the confinement in the narrow nanopore with restrictions imposed by the molecular stop and bias playing a lesser role. Understanding the interaction behavior of the polymer chain-stop molecule may lead to methods that decrease movement variation, facilitating an improvement on characterizing and identification of molecules. NSF DMR and CBET Grant No. 1352218.

Weak measurements and quantum weak values for NOON states

Science.gov (United States)

Rosales-Zárate, L.; Opanchuk, B.; Reid, M. D.

2018-03-01

Quantum weak values arise when the mean outcome of a weak measurement made on certain preselected and postselected quantum systems goes beyond the eigenvalue range for a quantum observable. Here, we propose how to determine quantum weak values for superpositions of states with a macroscopically or mesoscopically distinct mode number, that might be realized as two-mode Bose-Einstein condensate or photonic NOON states. Specifically, we give a model for a weak measurement of the Schwinger spin of a two-mode NOON state, for arbitrary N . The weak measurement arises from a nondestructive measurement of the two-mode occupation number difference, which for atomic NOON states might be realized via phase contrast imaging and the ac Stark effect using an optical meter prepared in a coherent state. The meter-system coupling results in an entangled cat-state. By subsequently evolving the system under the action of a nonlinear Josephson Hamiltonian, we show how postselection leads to quantum weak values, for arbitrary N . Since the weak measurement can be shown to be minimally invasive, the weak values provide a useful strategy for a Leggett-Garg test of N -scopic realism.

Manufacture of Nano Structures in Polymer Material

DEFF Research Database (Denmark)

Hansen, Hans Nørgaard; Pedersen, H.C.; Staun, Jacob

2003-01-01

The incorporation of micro and nano technology into the products of the future is an area of increasing interest. The ideas for new products based on this technology often take their starting point in specific scientific fields whereas the subsequent design and product development not necessarily...... is based on a systematic approach including manufacturing processes and production system capabilities. The process chain associated with micro and nano injection moulding usually comprises silicon or photoresist mastering, electroforming and polymer processing. Additionally, if the produced polymer...... components are to be used in a microsystem, subsequent handling and assembly is necessary. The present paper describes the process chain related to the manufacture of optical gratings with nanometer-sized structures. The problems of each process step and the challenges of establishing a coherent production...

Assessment on thermoelectric power factor in silicon nanowire networks

Energy Technology Data Exchange (ETDEWEB)

Lohn, Andrew J.; Kobayashi, Nobuhiko P. [Baskin School of Engineering, University of California Santa Cruz, CA (United States); Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California Santa Cruz, NASA Ames Research Center, Moffett Field, CA (United States); Coleman, Elane; Tompa, Gary S. [Structured Materials Industries, Inc., Piscataway, NJ (United States)

2012-01-15

Thermoelectric devices based on three-dimensional networks of highly interconnected silicon nanowires were fabricated and the parameters that contribute to the power factor, namely the Seebeck coefficient and electrical conductivity were assessed. The large area (2 cm x 2 cm) devices were fabricated at low cost utilizing a highly scalable process involving silicon nanowires grown on steel substrates. Temperature dependence of the Seebeck coefficient was found to be weak over the range of 20-80 C at approximately -400 {mu}V/K for unintentionally doped devices and {+-}50 {mu}V/K for p-type and n-type devices, respectively. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Comparison of silicon strip tracker module size using large sensors from 6 inch wafers

CERN Multimedia

Honma, Alan

1999-01-01

Two large silicon strip sensor made from 6 inch wafers are placed next to each other to simulate the size of a CMS outer silicon tracker module. On the left is a prototype 2 sensor CMS inner endcap silicon tracker module made from 4 inch wafers.

Optoelectronic properties of Black-Silicon generated through inductively coupled plasma (ICP) processing for crystalline silicon solar cells