• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.163-167
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• 2011

Nicotinamide adenine dinucleotide, $NAD^+$, and its reduced form, NADH, play important roles as coenzymes in many enzymatic reactions. Electrochemical methods for $NAD^+$ or NADH detection or generation are drawn attention because it can provide the simple and low cost platform with fairly good sensitivity. In this study, the polysiloxane viologen polymer/diaphorase/hydrophilic polyurethane (PSV/DI/HPU) modified electrodes were simply prepared and demonstrated for bio-electrocatalytic $NAD^+$ sensors. The electrodes were co-immobilized with diaphorase and polysiloxane viologen polymer as an electron mediator followed by the overcoating with HPU membrane. The mixture of the enzyme and the electron mediator was well stabilized within HPU membrane and exhibited good reversibility and stability. The sensitivity was 0.2 $nA{\cdot}{\mu}M^{-1}$ and the detection limit was 28 ${\mu}M$ with a response time of 50 s ($t_{90%}$). The capability for NADH sensor was also observed on the PSV/DI/HPU electrode.

• Macromolecular Research
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• v.11 no.6
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• pp.431-436
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• 2003

A new photoconducting polymer, diphenyl hydrazone-substituted polysiloxane, was successfully synthesized by the hydrosilylation method and characterized by FT-IR, $^1$H-NMR, and $^{29}$ Si-NMR spectroscopy. The glass transition temperature (T$_{g}$) of the polysiloxane having pendant diphenyl hydrazone was ca. 62 $^{\circ}C$, which enabled a component of a low-T$_{g}$ photorefractive material to be prepared without the addition of any plasticizers. This polysiloxane, with 1 wt% of $C_{60}$ dopant, showed a high photoconductivity (2.8 ${\times}$ 10$^{-12}$ S/cm at 70 V/${\mu}{\textrm}{m}$) at 633 nm, which is necessary for fast build-up of the space-charge field. A photorefractive composite was prepared by adding a nonlinear optical chromophore, 2-{3-[2-(dibutylamino)-1-ethenyl]-5,5-dimethyl-2-cyclohexenylidene} malononitrile, into the photoconducting polysiloxane together with $C_{60}$ . This composite shows a large orientation birefringence ($\Delta$n = 2.6 ${\times}$ 10$^{-3}$ at 50 V/${\mu}{\textrm}{m}$) and a high diffraction efficiency of 81 % at an electric field of 40 V /${\mu}{\textrm}{m}$.textrm}{m}$.EX>.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.59-66
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• 1991

This study was designed to investigate the marginal accuracy of resin temporary crown with different matrix in indirect technique. Matrices were made from irreversible hydrocolloid impression material, putty type of vinyl polysiloxane silicone rubber and vacuum formed plastic sheet. The marginal discrepancies of the temporary crowns were measured using a measuring microscope. The obtained results were as follows 1. The marginal accuracy temporary crown using vinyl polysiloxane silicone rubber or vacuum formed plastic form was better than that of the temporary crown using irreversible hydrocolloid impression material. 2. The marginal accuracies of the temporary crown using the irreversible hydrocolloid impression material and putty type of the vinyl polysiloxane silicone rubber obtained the best results at the distal measuring point. 3. The vacuum formed plastic form was recorded a more acceptable marginal accuracy at the distal and mesial measuring points.

• Journal of Adhesion and Interface
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• v.24 no.4
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• pp.124-130
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• 2023

For automotive coating agents that require little change in characteristics due to changes in external temperature, changes in noise characteristics due to changes in the external environment are very important. Therefore, soft polyurethane with excellent cold resistance, weather resistance, and abrasion resistance, and polysiloxane whose -OH terminated and side chains are modified with amines, are widely used. In this study, coating agents was prepared by adding water-born polyurethane, polysiloxane, ultra high molecular weight polypropylene (UHMWPP) powder, carbon black, and a matting agent to determine the effect of each resin component on noise. To study the effect of each resin component on noise, a coating agent was prepared by adding water-born polyurethane, polysiloxane, UHMWPP powder, carbon black, and a matting agent. The hard/soft segment ratio of water-born polyurethane, the main component of the coating, was 27.1%/72.9%, and the ratio of amino siloxanes to hydroxy-terminated polysiloxane was 2:7, which produced the least noise. The difference in friction coefficient was large when the friction body moves at high speed. When UHMWPP powder replaced SiO₂, noise decreased and gloss also decreased.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.133-137
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• 1987

Polysiloxane SE-54 liquid phase was immobilized on the support surface as coated in thin film via in-situ cross-linking. The cross-linking between liquid molecules was initiated by dicumylperoxide. Among the supports investigated, only Chromosorb W provided the cross-linkable surface. The optimal in-situ cross-linking was achieved when Chromosorb W was coated with 5% (w/w) SE-54 and cross-linked with 1% (w/w) dicumylperoxide. The cross-linked support was useful for the trace analysis as well as for the trace enrichment.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.249-259
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• 1989

Dental impression materials often become contaminated with patients' saliva and blood which creates the potential for cross-infection. It was the purpose of this study to investigate the effects of disinfection of three different rubber impression materials with four different disinfecting solutions. Polysulfide, vinyl polysiloxane and polyether impression materials were mixed according to the manufacturer's directions and samples were formed on a stainless steel model. On removal from the standard model, impressions were immersed in a disinfectant (acid-potentiated glutaraldehyde, phenollic compound, chlorine compound, iodophor) at room tempera tures for ten minutes. After disinfection, the distance between reference points(linear dimension) was measured using the non-contact automatic cordinate measuring projector(MZ-1, Nikon). Through statistical analyses on the data from this study,. the following conclusions were obtained. 1. Polysulfide, vinyl polysiloxane impressions were disinfected without dimensional change.(p>0.05) 2. Polyether impressions which were immersed in acid-potentiated glutaraldehyde were statistically different from control group.(p<0.05) But the amount of shrinkage(0.04%) would not be clinically significant. 3. By immersion of polysulfide, vinyl polysiloxane, polyether impressions in Banicide, Biocide, Multicide plus, sodium hypochlorite for ten minutes, clinically accurate impressions were obtained without dimensional change.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.360-367
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• 2011

Macroporous silicon carbide (SiC) ceramics were fabricated by powder processing and polymer processing using carbon-filled polysiloxane as a precursor. The effects of the starting SiC polytype, template type, and template content on porosity and flexural strength of macroporous SiC ceramics were investigated. The ${\beta}$-SiC powder as a starting material or a filler led to higher porosity than ${\alpha}$-SiC powder, owing to the impingement of growing ${\alpha}$-SiC grains, which were transformed from ${\beta}$-SiC during sintering. Typical flexural strength of powder-processed macroporous SiC ceramics fabricated from ${\alpha}$-SiC starting powder and polymer microbeads was 127 MPa at 29% porosity. In contrast, that of polymer-processed macroporous SiC ceramics fabricated from carbon-filled polysiloxane, ${\beta}$-SiC fillers, and hollow microspheres was 116MPa at 29% porosity. The combination of ${\alpha}$-SiC starting powder and a fairly large amount (10 wt%) of $Al_2O_3-Y_2O_3$ additives led to macroporous SiC ceramics with excellent flexural strength.

• Elastomers and Composites
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• v.27 no.4
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• pp.267-274
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• 1992

Polydimethylsiloxane(PDMS)-containing polyurethane coating materials were synthesized because PDMS-based elastomers have unique properties including an extremely low glass transition temperature, good thermal and oxidative stability, and good dielectric properties. In this experiment a vinyl copolymer which consisted of vinyl chloride, vinyl acetate, vinyl alcohol, and maleic acid was used, and Coronate L was used as a polyisocyanate. PDMS-containing polyurethane was synthesized from polydimethylsiloxane, MDI, and 1,4-butanediol. Films were casted by reaction of viny copolymer, Coronate L, and PDMS-containing polyurethane. Thickness of tile films were $150-170{\mu}m$ and the films were characterized by IR, DSC, and Instron.

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.162-162
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• 2000

• Polymer(Korea)
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• v.39 no.2
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• pp.311-316
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• 2015

Densely structured polyhedral oligomeric silsesquioxane (POSS) was employed as an additive to enhance hardness of silicon-based hybrid gels for LED encapsulants. To improve the miscibility of POSS and polysiloxane resin, alkyl or oligosiloxane branches were introduced to POSS moiety. Platinum-catalyzed hydrosilylation reactions were used to attach branches of 1-decanol, 9-decen-1-ol, and vinyl-terminated oligosiloxane to the POSS molecules. Alkyl-branched POSSs (decyl-POSS and decenyl-POSS) were immiscibile with polysiloxane resin and generated gels with low transparency and low hardness values. On the other hand, oligosiloxane-branched POSS (Siloxy-POSS) showed good miscibility with polysiloxane resin to give gels with high transparency. However, the prepared gels did not show noticeable improvement in hardness compared to the gels without the POSS additive.