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[9.5.1.1^3,9.1^5,15.1^7,13] 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. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2920–2928, 2001