Polysiloxane Poly Research Articles

Polysiloxane–poly(vinyl alcohol) composite dielectrics for high-efficiency low voltage organic thin film transistors

The strategy of composite polymer dielectrics for low consumption-high efficiency organic thin film transistors via the solution method.

Synthesis of Structured Lipids by Enzymatic Interesterification of Milkfat and Soybean Oil in a Basket-Type Stirred Tank Reactor

Lipase from Rhizopus oryzae immobilized on polysiloxane–poly(vinyl alcohol) (SiO2–PVA) was used to study the interesterification reaction of the milkfat with soybean oil in a stirred tank reactor (STR) containing baskets for the immobilized enzyme retention in two different configurations: central or lateral. The progress of the reaction was followed by determining free fatty acids, composition in triacylglycerols (TAGs), and consistency. The central basket was chosen for assessing the biocatalyst operational stability by running 10 consecutive batch assays lasting 6 h each. Non-notable deactivation of the biocatalyst was observed during the total operation time (60 h). The potential of the evaluated system to make the milkfat-based fat more spreadable under cooling temperature and with lower saturated fatty acids content was demonstrated in this study. Both evaluated basket reactor designs have shown potential to be used in interesterification reactions of industrial interest.

Extraction of polar and nonpolar biomarkers from the martian soil using aqueous surfactant solutions

The Life Marker Chip is being designed to detect the chemical evidence of life in the martian soil. It will use an aqueous surfactant solution to extract polar and nonpolar biomarkers from the martian soil and to transport them into an antibody-based detector for characterisation. Currently, a solution of 1.5gl−1 polysorbate 80 in 20:80 (vol:vol) methanol:water is being considered and appears to be suitable. Here, we have investigated the ability of a range of other surfactant solutions to extract a suite of eight standards spiked on the surfaces of the martian soil simulant JSC Mars-1 and tested the compatibility of the best two surfactants with a representative antibody assay for the detection of pyrene. The results show that using 20:80 (vol:vol) methanol:water as the solvent leads to increased recoveries of standards than using water alone. The poloxamer surfactants Pluronic® F-68 and Pluronic® F-108 are not effective at extracting the standards from JSC Mars-1 at any of the concentrations tested here. The fluorosurfactant Zonyl® FS-300 is able to extract the standards, but not as efficiently as polysorbate 80 solutions. Most successful of the alternative surfactants was the polysiloxane poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) which is able to extract the standards from JSC Mars-1 with an efficiency approximately equal to that of polysorbate 80 solutions of the same concentration. Enhanced recovery of the standards using polysorbate 80 and PDMSHEPMS solutions can be achieved by increasing the concentration of surfactant, from 1.5gl−1 to 10gl−1, leading to an increase in the recovery of standards of about 50%. Polysorbate 80 at concentrations of 1.5gl−1 and 10gl−1 and Zonyl® FS-300 and PDMSHEPMS (both at a concentration of 10gl−1) are also compatible with the representative pyrene antibody assay.

Polysiloxane–poly(propylene oxide) hybrid discs as solid phase in anti-HCV detection using a recombinant core protein

In this work, siloxane–poly(propylene oxide) discs (PPO disc) prepared using the sol–gel process were used as solid phase in enzyme-linked immunosorbent assays (ELISA) for the detection of anti-hepatitis C virus (HCV) antibodies. The HCV RNA from serum (genotype 1b) was submitted to the RT-PCR technique and subsequent amplification of the HCV core 408 pb. This fragment was cloned into expression vector pET42a and expressed in Escherichia coli as recombinant protein with glutathione S-transferase (GST). Cell cultures were grown and induced having a final concentration of 0.4 × 10 −3 mol L −1 of IPTG. After induction, the cells were harvested and the soluble fraction was analyzed using polyacrilamide gel 15% showing a band with an approximate molecular weight of 44 kDa, the expected size for this GST-fused recombinant protein. The recombinant protein was purified and confirmed by immunological detection using HCV-positive serum and showed no cross-reactivity with positive samples for other infectious diseases. An ELISA was established using 1.25 ng of recombinant protein per PPO disc, a dilution of 1:10,000 and 1:40 for a peroxidase conjugate and serum, respectively, and solutions of hydrogen peroxide and 3,3′,5,5′-tetra-methylbenzidine in a ratio of 1:1. The proposed methodology was compared with the ELISA conventional polystyrene-plate procedure and the performance of the PPO discs as a matrix for immunodetection gave an easy synthesis, good performance and reproducibility for commercial application.

Biodiesel Synthesis by Enzymatic Transesterification of Palm Oil with Ethanol Using Lipases from Several Sources Immobilized on Silica–PVA Composite

This work deals with the transesterification of palm oil with ethanol in a solvent free system using lipase from different sources (Thermomyces lanuginosus, Pseudomonas fluorescens, Burkholderia cepacia, Penicillium camembertii, and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane–poly(vinyl alcohol). This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country. The enzyme source showed strong influence on the transesterification yields, and the best performance was attained with the lipase from Pseudomonas fluorescens that reached almost full conversion (≅98 %) in less than 24 h of reaction. The purified product (biodiesel) was straw yellow in color and essentially odorless. Purity of the fatty acid ethyl ester was found to be high having no glycerol bound as verified by NMR 13C (APT, attached proton test). In addition, the other properties such as low water content (0.02%), specific gravity ...

Polysiloxane–poly(fluorinated acrylate) interpenetrating polymer networks: Synthesis and characterization

Combinations of fluorinated and silicone based elastomers were elaborated through the in situ synthesis of interpenetrating polymer networks (IPNs). The PDMS network was formed by dibutyltindilaurate catalyzed addition between the hydroxy end groups of α,ω-(3-hydroxypropyl)polydimethylsiloxane (PDMS) and a pluriisocyanate cross-linker. The poly(fluorinated acrylate) (polyAcRf6) network was obtained from free-radical copolymerization of a fluorinated acrylate with ethylene glycol dimethacrylate in the presence of dicyclohexyl peroxydicarbonate as the initiator. IPNs with different relative weight proportions of the fluorinated vs silicone partners were characterized by DMTA and DSC. Density refractive index and contact angle measurements reveal a satisfactory interpenetration degree of PDMS and polyAcRf6 networks. In addition, these materials present an unusual variation of density values and of the surface properties as a function of the relative weight composition.

Core–shell latex particles consisting of polysiloxane–poly(styrene-methyl methacrylate-acrylic acid): Preparation and pore generation

Latexes with a poly(dimethyl siloxane) core and a poly(styrene-methyl methacrylate-acrylic acid) [poly(St-MMA-AA)] shell have been prepared in two steps in order to generate particles that have a core with a very low glass transition temperature. In the first step, poly(dimethyl siloxane) particles were obtained via the ring-opening emulsion polymerization of octamethyl tetracyclosiloxane (D4). The polymerization was carried out using either an anionic or a cationic catalyst. In the first case, sodium hydroxide was used as catalyst and sodium dodecylbenzene sulfonate as surfactant, while in the second, the alkylbenzene sulfonic acid (ABSA) was used both as catalyst and surfactant. Using a PD4 latex as seed, a seeded emulsion polymerization of St-MMA-AA was conducted to obtain PD4–P(St-MMA-AA) core–shell particles. Numerous recipes were attempted and the most successful were those in which the seed was prepared with a cationic catalyst (ABSA) at a relatively low temperature (75°C). The core–shell structure of the particles was identified by transmission electron microscopy, but also via wetting angle, water absorption, and Tg measurements. Finally, pores were generated in the core–shell particles via an alkali–acid treatment. Because PD4 has a very low glass transition temperature, it cannot be easily handled. However, protected by a shell, it could be used as a constituent of composite materials with enhanced impact strength, even at very low temperatures. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2235–2245, 1999

Surface and solution properties of polysiloxane–poly(methyl methacrylate) graft copolymer

AbstractA polysiloxane–poly(methyl methacrylate) (PMMA) graft copolymer was prepared by hydrosilylation reaction between a SiH containing polysiloxane and an allyl‐terminated PMMA. The obtained graft copolymer was blended with PMMA homopolymer. The addition of only 0.01 wt % of graft copolymer was sufficient to make PMMA surfaces hydrophobic. In acetone–cyclohexane mixed solvent, the graft copolymer formed a polymeric micelle by the aggregation of PMMA branches.