Abstract: Alkyl-modified polymethylhydro-siloxane (R-PMHS) was prepared by polymethylhydro-siloxane (PMHS) and 1-dodecene though hydrosilylation,with chloroplatinic acid/ethanol as catalyst.Effects of reaction temperature,reaction time and catalyst dosage on the grafting effectiveness of R-PMHS were discussed.Results showed that the suitable conditions for synthesis of R-PMHS were as follows:reaction temperature,100 ℃;reaction time,5 h;catalyst (m(chloroplatinic acid)/m(ethanol)=1/500) dosage,0.25% of the mass of 1-dodecene.Under the above said conditions,the grafting effectiveness could reach 97.27%.Then alkyl-modified silicone elastomer gel (R-SEG) was prepared with R-PMHS as matrix,vinyl-terminated polydimethylsiloxane (Vi-PDMS) as crosslinking agent,decamethylcyclopentasiloxane (D₅) as swelling agent,chloroplatinic acid as catalyst.Effect of mole ratio n(1-dodecene)/n(Si-H) on the swelling extent and oil compatibility of the R-SEG were studied.Results showed that R-SEG's swelling extent and compatibility increases with the increase of mole ratio n(1-dodecene)/n(Si-H) in the range of 0.1 to 0.4,a uniform and transparent gel forms when n(1-dodecene)/n(Si-H) reaches 0.3.

Key words: silicone elastomer, alkyl-modified, grafting, swelling, synthesis