Thermal and autoxidation reactions of poly‐3‐methylenecyclobutene and poly‐1‐methyl‐3‐methylenecyclobutene

Abstract

The thermal ring‐opening reactions, autoxidation and hydrogenation of polymethy‐lenecyclobutene (PMCB) and poly‐1‐methyl‐3‐methylenecyclobutene (PMMCB), were investigated. Both polymers were prepared by cationic polymerization and consisted almost entirely of 1,5‐repeating units containing cyclobutene rings in the polymer backbone. Both polymers showed well behaved exothermic processes at elevated temperatures which apparently resulted in crosslinking. These processes were investigated by differential scanning calorimetry and interpreted to involve thermal ring‐opening reactions. Autoxidation occurred very rapidly in PMCB but much more slowly in PMMCB as predicted by Bolland's rules. Attempts to hydrogenate the cyclobutene rings in both polymers resulted in the occurrence of hydrogenolysis in PMCB and little or no reaction with PMMCB for a Pd‐catalyzed reaction and partial hydrogenation of the latter for a diimide reaction.