Homopolymer and Random Copolymer of Polyhedral Oligomeric Silsesquioxane (POSS)-Based Side-Chain Polynorbornenes: Flexible Spacer Effect and Composition Dependence

Abstract

A series of homopolymers and random copolymers of polyhedral oligomeric silsesquioxane (POSS)-based side-chain polynorbornenes were prepared using ring-opening metathesis polymerization. For the homopolymer P-z-POSS (z represents the spacer length, z = 5, 12, and 17), the POSS groups tethered to the side chain are linked to the polynorbornene backbone through the flexible spacer with different lengths. For the random copolymer P-6-co-17(X/Y) (X/Y = 1/1, 3/1, 6/1, and 9/1), the composition was regulated by adjusting the molar feed ratio X/Y of the norbornene monomer with butyl ester side group (M-6) to the POSS containing monomer with the longest spacer (M-17-POSS). Using various techniques, we studied the spacer length effect on POSS crystallization of the homopolymers and the composition dependence of physical properties of the copolymers. It is found that P-5-POSS is amorphous. On the contrary, POSS crystallization is observed in P-12-POSS and P-17-POSS, and the longer the spacer is, the higher the POSS...