Synthesis of polyethylene hybrid copolymers containing polyhedral oligomeric silsesquioxane prepared with ring‐opening metathesis copolymerization

Ring‐opening metathesis copolymerizations of cyclooctene and the polyhedral oligomeric silsesquioxane (POSS) monomer 1‐[2‐(5‐norbornen‐2‐yl)ethyl]‐3,5,7,9,11,13,15‐heptacyclopentylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane (POSS–norbornylene) were performed with Grubbs's catalyst, RuCl2(CHPh)(PCy3)2. Random copolymers were formed and fully characterized with POSS loadings as high as 55 wt %. Diimide reduction of these copolymers afforded polyethylene–POSS random copolymers. Thermogravimetric analysis of the polyethylene–POSS copolymers under air showed a 70 °C improvement, relative to a polyethylene control sample of similar molecular weight, in the onset of decomposition temperature based on 5% mass loss. The homopolymer of POSS–norbornylene was also synthesized. This polymer had a rigid backbone according to 1H NMR evidence of broad olefinic signals.