Synthesis of high performance cyclic olefin polymers using highly efficient WCl6-based catalyst system

Abstract

Cyclic olefin polymers (COPs) with high glass transition temperature, high transparency (higher than 80%) in the visible light range, excellent thermal stability and outstanding mechanical properties have been synthesized by effective ring opening metathesis polymerization (ROMP) of exo-1,4,4a,9,9a,10-hexahydro-9,10(1′,2′)-benzeno-l,4-methanoanthracene (HBM) and dicyclopentadiene (DCPD) or norbornene (NBE) using WCl6/i-Bu3Al/ethanol/1-hexene catalyst system, followed by hydrogenation of double bonds. 1-Hexene acted as a molecular weight controller in the polymerization reaction, tuning the number-average molecular weight (Mn) of P-HBM from 5.8 × 104 to 41.1 × 104. The monomer composition and thermal properties of the copolymers were characterized by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The saturated polymers exhibited high decomposition temperatures (Td) around 340 °C and glass transition temperatures (Tg) in the range from 117.5 °C to 219.7 °C. What is more, tensile tests indicated that the mechanical properties of the COPs could be effectively tuned in a wide range by introducing varying amount of small cyclic olefin such as DCPD or NBE.