Surface treated silicas
View Patent ↗Disclosed is a silica substrate treated with a polysiloxane, and an organosilane, wherein the organosilane is described by the formula: RSi(R′) x (OR″) 3-x ; wherein R is a long-chain hydrocarbon group having between about 8 to about 30 carbon atoms, which may also contain organofunctional groups such as vinyl, methacryl, amino, sulfur, and epoxy groups; R′ and R″ are independently selected from a methyl and ethyl group; and X is either 0 or 1. The optimal use for the treated silica substrate is as a rheology modifier in epoxy polymer materials, however, the silica substrate could also be used in other chemical compositions such as polyurethanes, polyesters, silicones, and hydrocarbon oils.
1. A method of preparing a treated silica substrate comprising the sequential steps of:
a) providing silica particles;
b) contacting the silica particles with at least one polysiloxane conforming to formula (I)
wherein n is an integer greater than 1, preferably between about 30 to about 100;
X is selected from a hydrogen atom or an R′ group, preferably methyl;
R, R′ are independently selected organic groups, with from about 1 to about 20 carbon atoms; and
Y and Z are silicon-containing terminating end groups, preferably Y is —OSi(CH 3 ) 3 and Z is —Si(CH 3 ) 3 ; and
c) contacting the silica particles with an organosilane described by the formula:
RSi(R′) x (OR″) 3-x (II)
wherein R is a lone-chain hydrocarbon group having between about 8 to about 30 carbon atoms, and optionally contains organofunctional groups selected from the group consisting of vinyl, methacryl, amino, sulfur, and epoxy groups; R′ and R″ are independently selected from the group consisting of a methyl and an ethyl; and X is either 0 or 1.
2. The method of claim 1 , wherein the silica particles are provided by precipitation.
3. The treated silica substrate produced by the method of claim 1 .
4. A polymer composition comprising the treated silica substrate of claim 3 .
5. The polymer composition according to claim 4 , further comprising a polymer selected from the group consisting of epoxy resin, polyurethanes, polyesters, silicones, and hydrocarbon oils.
6. The polymer composition according to claim 4 , wherein the STI of the polymer composition is about 1.2 to about 100.
7. The polymer composition of claim 6 wherein the STI of the polymer composition is about 1.4 to about 5.