Oxidation and epoxidation of poly(1,3-cyclohexadiene)

Poly(l,3-cyclohexadiene) (PCHD) derivatives were synthesized via facile chemical modification reactions of the residual double bond in the repeat unit. The oxidation and degradation of PCHD was investigated to enable subsequent controlled epoxidation reactions. PCHD exhibited a 15% weight loss at 110°C in the presence of oxygen. The oxidative degradation, demonstrated by gel permeation chromatography (GPC) and ¹H NMR spectroscopy, was attributed to main-chain scission. Aldehyde and ether functional groups were introduced into the polymer during the oxidation process. PCHD was quantitatively epoxidized in the absence of deleterious oxidation with meta-chloroperoxybenzoic acid. ¹H and ¹³C NMR spectroscopy confirmed that polymers with controlled degrees of epoxidation were reproducibly obtained. Epoxidized PCHD exhibited a glass-transition temperature at 154°C, which was slightly higher than that of a PCHD precursor of a nearly equivalent molecular weight. Moreover, GPC indicated the absence of undesirable crosslinking or degradation, and the molecular weight distributions remained narrow. The thermooxidative stability of the fully epoxidized polymer was compared to that of the PCHD precursor, and the epoxidized PCHD exhibited an initial weight loss at 250°C in oxygen, which was 140°C higher than the temperature for PCHD.