Vinyl-silicon polymers

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The formulation ofmoisture-ujriiig silicones includes a silicone polymer, filler, a moisture-reactive cross-linker, and sometimes a catalyst. A newer class of silicone sealants are known as the silicone latex sealants. These sealants are silicone-in-water emulsions that cure by evaporation of the emulsifying water. Addition-curing silicones in general are two-part systems that cure by the platinum-catalyzed reaction of a silicone hydride with typically a vinyl group attached to silicon. Because no by-products are generated by the cure, there are few volatiles and no shrink in thick sections. 

The silicon-metal doubly bonded compounds can further react to yield desired derivatives. Recently, vinyl magnesium bromide was reported to react with chloro complexes containing chromium or iron double bonds to silicon, to yield the l-metalla-2-sila-l,3-diene compounds (115, equation 34), which can potentially be used to functionalize silicon polymers in a desired fashion121. 

The Silicone Polymers. The silicone polymers have the backbone structure shown in Figure 8.15 in which all the alkyl groups are shown as methyl. Replacement of the methyl groups with others of higher polarity yields polymers of increasing polarity. Since one company, Ohio Valley Speciality Chemical, produces a complete line of these products, Table 10 contains a list of their products by OV number. Those indicated by an asterisk are available in a special formulation on OT columns, and most of them contain 1% vinyl groups to improve stability. Other manufacturers phases equivalent to the OV phases are given in Table 11. 

The tests were carried out on 1 1 mixtures of two components (A component = polymer + Pt catalyst B component = polymer + crosslinker) which were prepared shortly before the test. The catalyst was a vinyl siioxane Pt complex with tetramethyltetravinylcyclotetrasiloxane as a ligand. All the polymers and crosslinkers used were equilibrated and devolatized products with a molar mass distribution typical for silicone polymers. 

INTEX STABILIZER 17 is an additive to a pad bath designed to give better heat and shear stability to emulsion systems in the presence of inorganic salts. It will stabilize acrylic soil release polymers, acrylic polymers, vinyl acetate polymers, styrene butadiene polymers, urethane emulsions and silicone emulsions. 

Ethylene-vinyl acetate polymer Ethylene-vinyl chloride Ethylene-vinyl chloride copolymer Fatty acid amide Fatty acid amides Fatty acid amine and silicone blend... 

A different way to introduce silicone type sequences in copolymers is to attach acrylate end groups to a poly[oxy(dimethylsilylene)], followed by copolymerization in a vinyl type polymer. The introduction of silicone groups leads to a crosslinked material similar to that obtained with poly(ethylene glycol) dimethacrylate. The structure of a copolymer with silicone crosslinking bridges is shown below ... 

In parallel with these developments, organotin compounds have found a variety of applications in industry, agriculture, and medicine, though in recent years these have been circumscribed by environmental considerations. In industry they are used for the stabilization of poly(vinyl chloride), the catalysis of the formation of the polyurethanes, and the cold vulcanisation of silicone polymers, and also as transesterification catalysts. 

The other important type of polymer contains a hydrogen atom attached directly to silicon. These polymers would be very similar in structure to those shown above, (IV), (V), and (VI), if hydrogen groups were substituted for vinyl. These polymers are usually lower in molecular weight and viscosity. Oligomers such as (VIHa-c) have also been used. The combinations and ramifications are nearly limitless in siloxane chemistry. 

The silicone semi-lPNs consist of mixing a hydride-containing silicone prepolymer and a vinyl functionalized silicone polymer into a thermoplastic matrix such as PA, PBT, thermoplastic polyurethane (TPU) or styrene-ethylene/butylene-styrene (S-EB-S) block copolymer elastomer. The two silicone prepolymers co-react in the thermoplastic matrix during melt extrusion and injection molding to form a partially crosslinked network within the thermoplastic matrix. 

Typically, the silicon atoms will have one or more organic side groups attached to them, generally phenol (CHgHs-), methyl (CH3), or vinyl (CH2=CH-) units. These groups impact properties such as solvent resistance, lubricity, and reactivity with organic chemicals and pol)nners. Silicone polymers may be filled or unfilled, depending upon the properties required and the application. 

Chem. Descrip. Aq. emulsion of a high-visc. silicone polymer Uses Cures to a durable, detergent-resistant film for mold release, particle treatment, textile finishes, fabric softener, hand modifier, vinyl and auto polish applies, (requires catalyst) resin extender Properties Wh. emulsion water-disp. dens. 8.30 Ib/gal vise. 10,000 cst ... 

Figure 3 Common units found in silicone polymers (a) PDMS, (b) a methyl vinyl silicone monomer unit, and (c) a methyl hydrogen (silane) siloxane unit.

Synonyms Siloxanes and silicones, dimethyl, mono [[3-[(2-aminoethyl) amino] propyl] dimethoxysilyl] oxy-terminated Classification Silicone polymer Uses Emulsifier for cosmetics for water repellents, car polishes, leather treatment, textile lubricants, vinyl conditioners Trade Name Synonyms GP-RA-157 Silicone Fluid [Genesee Polymers http //www.gpcsilicones.com]] PS401 [United Chem. Tech, http //www.unitedchem.com]... 

Summary Carborane-hybridized silicon polymers were synthesized from the hydro-silylation reaction between diethynylbenzene-silylene polymers with reactive vinyl side groups and 1,7-bis(dimethylsilyl)carborane and l,7-bis(diphenylsilyl)carborane. Precise NMR spectroscopic studies show that the structures of these polymeres were quite complicated unreacted vinyl groups and pendant carborane substitution exist along with crosslinked carborane. These polymers show plastic moldability. Thermal treatment of the hybrid polymers gives excellent stability in both thermal and mechanical properties of the polymers. Their unreacted moieties seem to act as crosslinkable thermosetting features to make these polymers more stable. 

While main chain strategies gave inefficient results, introduction of carborane to side chains is a relatively easy way to make hybrid systems. As Kunai reported, the versatile hydrosilylation reaction is the most reliable way to build hybrid polymers [9]. Reaction between diethynylbenzene-silylene polymers with reactive vinyl side groups 1 and l,7-bis(dimethylsilyl)carborane [HSi(CH3)2-(CBioH oC)SiH(CH3)2] 2a (R = CH3) in the presence of hydroplatinic acid catalyst gave carborane-hybridized silicon polymers 3a with 67 % yield (Scheme 1). GPC measurement of 3a provides a 21600 A/w vs. polystyrene standard, while the original polymer 1 had 6400. l,7-Bis(diphenylsilyl)carborane 2b (R = Ph) was also reacted with polymer 1 to get a similar hybrid 3b with a lower yield and Mfy, only 43 % and 5 800 respectively. Here hybrid silicon polymers with carborane side groups have been synthesized successfully. 

The hydrosilylation reaction (see Scheme 3) is strictly speaking a platinum-catalysed addition of a Si-H group of silicon-hydrogen-functionalised crosslinking agents to the double bond of vinyl-group-functionalised silicone polymers. 

Two-part RTVs Vinyl-terminated silicone polymers [Polymer VS 50,100, 200, and 1,000 (Anderson Assoc.)] Potysihcon hydride cross-hnkers 100, 101,120 (Anderson Assoc.) and 200-1210 (Anderson Assoc.) with pendant/terminal functionalities. HMS-031, HMS-151, and HMS-301 (Gelest). Platinum-complex catalysts 500, 511, 5112 [0.05-2% Pt (Anderson Assoc.)], and PC 074 and 075 (United Chemical Tech.)... 

The silicone coating system used reacted via addition cure chemistry comprised a vinyl- and a hydride-functional silicone polymer. 

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