Abstract: Alkyl-modified polymethylhydrosiloxane (R-PMHS) with different percent grafting of alkyls was prepared by hydrosilylation of 1-dodecene and polymethylhydrosiloxane (PMHS).The alkyl-modified silicone elastomer microspheres were prepared by Pickering emulsion polymerization with R-PMHS and vinyl-terminated polydimethylsiloxane (Vi-PDMS) as oil phase and the hydrophilic nano-SiO₂ particles and a small amount of cetyltrimethylammonium bromide (CTAB) as emulsifiers.The results show that the most stable emulsion together with the best morphology of microspheres were obtained when the concentration of CTAB is 2×10^-4 mol/L,the mass ratio of oil to water is 1∶1,the mass fraction of nano-SiO₂ to oil phase is 4% and the molar ratio of silicon-hydrogen bond (Si-H) to vinyl is 2∶1.The oil absorption results show that the lipophilicity of these silicone elastomer microspheres increases with the increase of percent grafting of alkyls.

Key words: raw material of cosmetics, silicone, hydrosilylation, alkyl modification, emulsion polymerization, microsphere