Dow Corning Corporation

Thomas F Lim

Duane R Bujalski

Antony P Wright

Gary E LeGrow

Jonathan Lipowitz

Chi-long Lee

Daniel Graiver

Alan L Freiberg

Gary E Le Grow

Gary E DeGrow

Alkylpoly(polysilyl)azanes are prepared by the reaction of chlorine-containing polysilane preceramic polymers and various disilazanes. The alkylpoly(polysily)azanes may be converted to ceramic materials by pyrolysis at elevated temperatures.

Alkylpoly (polysilyl) azane preceramic polymers

Chlorine or bromine-containing polysilanes of the general formula (R.sub.2 Si)(RSi)(R'Si) are disclosed. In these polysilanes there are also bonded to the silicon atoms other silicon atoms and chlorine or bromine atoms, R is an alkyl radical containing 1 to 4 carbon atoms, and R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A.sub.y X.sub.(3-y) Si(CH.sub.2).sub.z -- wherein each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1. These preceramic polymers can be pyrolyzed at elevated temperatures under an inert atmosphere to yield ceramic materials or articles. These polysilanes may also be converted into other preceramic polymers which can be pyrolyzed to ceramic materials or articles.

Polysilane preceramic polymers

A method is described to prepare preceramic polysilanes which contain at least one weight percent vinyl. To ensure the survival of the vinyl groups in the polysilane the reaction and process conditions must be carefully controlled. The vinyl-containing polysilanes can be formed into fibers, cured either thermally or by UV irradiation, and then pyrolyzed to form ceramic fibers. Thermal curing and pyrolysis can be combined into a single process step.

Method of producing silicon carbide preceramic vinyl-containing polymers

Vinyl-containing polysilanes are described wherein the vinyl groups are attached to endblocking sites of intermediate reactivity. These vinyl-containing polysilanes are prepared by reacting a halogen-endblocked polysilane with, first, a non-vinyl-containing Grignard reagent or a non-vinyl organolithium compound whereby the most reactive halogen endblocking groups are replaced; then, second, reacting the resulting polysilane with vinyl Grignard reagent or vinyllithium whereby the halogen endblocking groups of intermediate reactivity are replaced; and, third, reacting the resulting polysilane with a non-vinyl-containing Grignard reagent or a non-vinyl organolithium compound whereby the least reactive halogen endblocking groups are replaced. The vinyl-containing polysilanes can be coverted to ceramic materials, including ceramic fibers, by pyrolysis.

The shelf life of an aqueous, anionic silicone emulsion, which contains an organic tin compound and which forms an elastomer upon removal of the water, is improved by the addition of an additive. The additive is selected from the group consisting of alkyl mercaptan, 8-quinolinol, thioglycolic acid, and salts of thioglycolic acid. Elastomers produced by removing the water from these emulsions, once shelf aged, have more consistent physical properties than do elastomers produced from similar emulsions not containing the additives.

Silicone water-based emulsions having improved shelf life

A novel class of resinous organosiloxane polymers includes triorganosiloxy, fluorinated organosiloxy, SiO.sub.4/2 and silicon-bonded hydroxyl groups. The fluorine-containing hydrocarbon radicals are bonded to silicon by means of a sequence of at least two methylene group. Preferred organosiloxane polymers stabilize the cellular structure of polydimethylsiloxane foams during curing.

Fluorinated organosiloxane copolymers

A novel class of organosiloxane copolymers are prepared by the reaction of (1) a silane containing from 1 to 3 hydrolyzable groups and a fluorinated hydrocarbon radical that is bonded to silicon through a --CH.sub.2 CH.sub.2 -- radical, and (2) a resinous organosiloxane copolymer containing trimethylsiloxy units, SiO.sub.4/2 units and silicon-bonded hydroxyl groups.

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Midland, MI, United States of America

Thomas F Lim