End-groups and tacticity in polymeric silicones detected by 29Si nuclear magnetic resonance

Abstract

It is shown that for a polymeric silicone of average chain-length 50 units (excluding the end-stopping groups) separate ²⁹Si {¹H}resonances can be seen for the three units at each end, and tacticity effects can also be observed when asymmetric units are involved (in the case investigated the silicone is probably atactic); tacticity effects on ²⁹Si spectra are also demonstrated for a shortchain silicone.