New method to con­vert el­e­men­tal sil­i­con to us­able chlorosi­lane

Chemical Industry Digest - - New Developments -

The broad spec­trum of ap­pli­ca­tions for sil­i­cones ranges from med­i­cal im­plants and cos­met­ics to hy­draulic oils and sealants to cor­ro­sion pro­tec­tion. To op­ti­mize sil­i­con-based syn­thetic ma­te­ri­als for spe­cific ap­pli­ca­tions, madeto-mea­sure chlorosi­lane build­ing blocks are re­quired in or­der to pro­duce and crosslink the longchain poly­mers. This in­flu­ences the ma­te­rial’s vis­cos­ity and flow prop­er­ties.

Con­ven­tion­ally, the MüllerRo­chow Di­rect Process has formed the back­bone of the sil­i­cone in­dus­try. In this process, ele­men­tary sil­i­con is con­verted with methyl chlo­ride into methyl chloro si lanes at high tem­per­a­tures and pres­sures in the pres­ence of a cop­per cat­a­lyst. Re­searchers have now devel­oped a com­ple­men­tary process that has sev­eral ad­van­tages over the Di­rect Process: It uses hex a ch lo rodi si lane and chlo­ri­nated hy­dro­car­bons as start­ing ma­te­ri­als and works un­der room tem­per­a­ture and nor­mal pres­sure. To ac­ti­vate it, just a small con­cen­tra­tion of chlo­ride ions is needed in place of a cat­a­lyst.

The chemists be­lieve that the chlorosi­lane monomers formed by this method are spe­cial and their po­ten­tial lays in the fact that they con­tain not only sil­i­con-chlo­rine bonds but also car­bon-car­bon mul­ti­ple bonds. The pur­pose of the former is to con­struct the in­or­ganic sil­i­con-oxy­gen chains; the lat­ter can be linked to form or­ganic poly­mers. This unique com­bi­na­tion per­mits new routes to in­or­ganic-or­ganic hy­brid ma­te­ri­als.

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