Synthesis and properties of cyclic olefin polymers by ring-opening metathesis (co)polymerization of α-methyl-substituted norbornene lactones

Abstract

Previously, we prepared new cyclic olefin polymers (COPs) by performing a ring-opening metathesis polymerization (ROMP) of endo- and exo-norbornene lactones (NBLs) and then hydrogenation. In this study, we produced new thermally and chemically stable COPs with random, gradient, and block sequences by homo- and copolymerizing endo- and exo-methyl-substituted NBLs (MNBLs) with norbornene (NB), in addition to the COPs obtained by copolymerizing NBLs with endo,anti-tetracyclododecene (TCD). The rates of ring-opening metathesis copolymerization (ROMCP) between endo- and exo-MNBLs, endo- and exo-NBLs, TCD, and NB are compared, and the random copolymers are prepared by dropwise addition of more reactive monomers. The thermal and optical properties, structural analysis, and hydrophobicity of the resultant COPs are investigated. The block and gradient hydrogenated copolymers (H-poly(endo-MNBL-co-NB)) are crystalline, yet the corresponding random copolymer is amorphous. Notably, the COPs obtained from MNBLs and NBLs show lower birefringence values than a conventional linear-ester-substituted COP, ARTON®.