Patent ID: 8895145

Claim:
A method of preparing hydrophobic silica particles comprising: a) providing a hydrosiloxane agent having the following formula wherein R 1 =—H, —CH 3 , R 2 =—H, —CH 3 , R 3 =—CH 3 , —CH 2 CH 3 , —CH 2 CH 2 CH 3 , —CH 2 Ar, —CH 2 CH 2 Ar, —Ar, —CH 2 CH 2 CF 3 , or —CH 2 CH 2 —R f with R f being a C 1 to C 8 perfluoroalkyl group, R 4 =—CH 3 , —CH 2 CH 3 , —CH 2 CH 2 CH 3 , —CH 2 CH 2 CF 3 , or —CH 2 CH 2 —R f with R f being a C 1 to C 8 perfluoroalkyl group, R 5 =—CH 3 , —CH 2 CH 3 , —CH 2 Ar, —CH 2 CH 2 Ar, or —Ar, R 6 =—H, —OH, —OCH 3 , or —OCH 2 CH 3 , Ar is unsubstituted phenyl or phenyl substituted with one or more methyl, halogen, ethyl, trifluoromethyl, pentafluoromethyl, or —CH 2 CF 3 groups, n, m, and k are integer numbers; n≧1, m≧1, k≧0, and wherein the hydrosiloxane agent has a number average molecular weight from 282 to about 20,000; b) contacting silica particles with the hydrosiloxane agent in the presence of a solvent, the solvent, silica particles, and hydrosiloxane agent forming a reaction mixture, wherein the reaction mixture has a pH from about 2 to about 6 or from about 8 to about 12 and wherein, when R 6 is —H, the solvent comprises at least one of water, methanol, and ethanol; and c) drying the reaction mixture to provide hydrophobic silica particles.