Terpolymerization of ethylene, norbornene and dicyclopentadiene catalyzed by modified cyclopentadienyl scandium complexes

Cyclic olefin copolymers (COCs) with high glass-transition temperature (T-g) are of fundamental interest and practical importance. Herein we report the terpolymerization of ethylene (E), norbornene (NB) and dicyclopentadiene (DCPD) catalysed by fused-heterocyclic and pyridyl-modified cyclopentadienyl scandium complexes (1 and 2) in high activities (1.27 to 1.86 x 10(6) g mol(Sc)(-1) h(-1) bar(-1)) to produce E/NB/DCPD terpolymers with adjustable structures. The terpolymerization proceeded in a controlled fashion, forming E/NB/DCPD terpolymers with moderate number average molecular weight (M-n = 4.9 x 10(4)-13.6 x 10(4) Da) and relatively narrow polymer dispersity index (PDI = 1.7-2.3). By controlling the concentration of NB and DCPD in-feed, a series of terpolymers with NB + DCPD contents from 47.4 mol% to 59.8 mol% (NB 17.7 mol% to 42.2 mol%, and DCPD 8.8 mol% to 38.6 mol%) was obtained. The highest total cycloolefin incorporation was more than 50 mol%, indicating the existence of continuous cycloolefin -E(NB)(DCPD)E- units as proved by H-1, C-13, H-1-H-1 COSY, H-1-C-13 HSQC and H-1-C-13 HMBC NMR spectroscopy. This phenomenon has not been observed in the binary copolymerization of E/NB and E/DCPD catalysed by rare earth catalyst systems in reported publications. The surprising finding may be ascribed to the use of two kinds of cycloolefins and novel efficient scandium catalysts. Hetero-cycloolefins promoted the cyclic olefin insertion of each other for rare earth catalysts. T-g values of the terpolymers range from 133.4 degrees C to 162.8 degrees C, which is in good agreement with NB and DCPD incorporation. The high DCPD content provides greater contribution to the high T-g value compared with NB in terpolymers. Further transformation of the C=C double bond in E/NB/DCPD terpolymers to the hydroxyl group was achieved via sequential epoxidation and hydroxylation reactions, resulting in a huge increase of T-g from 162.8 degrees C to 202.3 degrees C and a large decrease in the water contact angle from 84.1 degrees to 33.4 degrees.

Automated summary

We report the terpolymerization of ethylene, norbornene, and dicyclopentadiene using fused-heterocyclic and pyridyl-modified cyclopentadienyl scandium complexes. The resulting E/NB/DCPD terpolymers exhibited adjustable structures and high glass-transition temperature. The incorporation of cycloolefin units into the terpolymers was observed and attributed to the use of two kinds of cycloolefins and efficient scandium catalysts.