Synthesis of Norbornene and Methyl Methacrylate Graft Copolymers with High Norbornene Content by Using Mixed Catalytic System

摘要

A vinyl-type polymer of norbornene containing a few pendant styrene groups obtained by copolymerization of norbornene and 1,4-divinylbenzene (1,4-DVB) was used as a macroinitiator in the reverse atom transfer radical polymerization (RATRP) of methyl methacrylate in conjunction with CuCl_2/2,2'-bipyridine/2,2'-azobisisobutyronitrile (AIBN) as a catalyst. In the first step of the reaction, the structural characterization of the copolymers showed that norbornene and 1,4-divinylbenzene copolymerizations occur as a coordination mechanism and that true copolymers are formed by random copolymerization. With the initiation of copper dichloride and AIBN in the second step, the pendant styrene groups in the copolymers were quantitatively polymerized with methyl methacrylates, which allowed the successful synthesis of polynorbornene-based graft copolymers by RATRP mechanism. The analyses of the product by ~1 H-and ~(13)C-NMR and GPC gel permeation chromatography (GPC) gave the verification of `true' copolymer. Varying the monomer feed ratio controlled the thermal property of the graft copolymer.