Substituent Effect of Styryl Monomers on Composition and Property Enhancement of Dicyclopentadiene-Based Cycloolefin Copolymers

Cyclic olefin copolymers based on dicyclopentadiene (DCPD) are very attractive due to the readily available DCPD resource, where the dangling C=C bonds are reactive and facilitate postpolymerization functionalization but also facilely lead to cross-linking; thus, their potential applications are soundly unsuccessful. Herein, we report the successful terpolymerizations of ethylene and DCPD and styryl monomers by using the fluorene methylene pyridine scandium complex. Among the styryl comonomers, p-fluorostyrene (SF) dramatically enhanced the polymerization activity and the incorporation of DCPD. The resultant E/DCPD/SF terpolymers show higher elongation at break and breakdown voltage than the E/DCPD copolymer while maintaining a similar optical property and tensile stress to the latter. In particular, the introduction of the third SF comonomer significantly depresses the cross-linking aroused by the dangling C=C bonds, which is attributed to the superconjugating interaction of the phenyl rings. This work paves a new avenue to the trade-off for the DCPD-based cyclic olefin copolymers with respect to synthesis and applications.