Dow Corning Corporation

University of South Australia

Stephen Ross Clarke

Daniel Graiver

Michael James Owen

Janis Gunars Matisons

A process for manufacturing high molecular weight, alternating polysiloxane copolymers, by solid-liquid phase, nonaqueous, interfacial polymerization. The copolymers consist of alternating siloxane repeating units of the (AB).sub.m type, such as diphenylsiloxane units and dimethylsiloxane units, alternately polymerized together to form the copolymer. The solid-liquid phase interfacial polymerization process is fast, proceeds smoothly at room temperature, and is not reversible, i.e., no cyclic siloxane species are generated. The resulting polysiloxanes can be formed into thermoplastic elastomers which are suitable for use as sealants, fillers, and films.

Solid-liquid phase interfacial polymerization

Dialkali metal organosilanolate and dialkali metal organosiloxanolate salts are manufactured from cyclic siloxanes or linear silicone polymers using a heterogeneous interfacial reaction process. A stoichiometric excess of an alkali metal hydroxide such as potassium hydroxide or an alkali metal oxide as a solid or dissolved or dispersed in a compatible solvent, is prepared and used as a first phase. The cyclic siloxane or linear silicone polymer is placed in a second phase either dissolved or dispersed in another solvent which is immiscible with the first phase. The resulting silanolate and siloxanolate salts can be used as monomers for solid-liquid phase and liquid-liquid phase interfacial polymerization or in a polycondensation process for the synthesis of alternating siloxane polymers. They can also be used as ring opening initiators for the base catalyzed polymerization of cyclic siloxanes.

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Morphett Vale, Australia

Stephen Ross Clarke