Radical-Mediated Graft Modification of Polyethylene Models with Vinyltrimethoxysilane: A Fundamental Study

Cross-linked polyethylenes have widespread applications such as insulators for current-carrying wires/cables and for hot water pipes. Industrially, cross-linked polyethylene can be prepared via the radical-initiated grafting of polyethylene with vinyltrimethoxysilane (VTMS) followed by moisture-induced cross-linking. The efficiency of the grafting reaction is not optimal: (1) a large portion of the VTMS remains unreacted and (2) controlling the distribution and extent of grafting is difficult. We present new contributions to the fundamental understanding of grafting reactions with VTMS on polymeric models (dodecane and heptane) as to the effect of phenyllithium capping reaction time on the analyses, the origin of the observation of multiple grafts, and the regiochemistry of the multiple graft products.