Microstructure of copolyperoxides of α-methylstyrene with styrene and methyl methacrylate

Abstract

This paper reports a study on the microstructure of two series of copolyperoxides of α-methylstyrene, with styrene and with methyl methacrylate. The copolyperoxides were synthesized by the free radical-initiated oxidative copolymerization of the vinyl monomer pairs. The copolyperoxide compositions obtained from the ¹H and ¹³C NMR spectra led to the determination of the reactivity ratios. The product of the reactivity ratios indicates that α-methylstyrene forms a block copolyperoxide with styrene and a random copolyperoxide with methyl methacrylate. Microstructural parameters like average sequence length, run number, etc. have been determined for the latter copolyperoxide from analysis of its ¹³C NMR spectrum. The aromatic quaternary and carbonyl carbons were found to be sensitive to triad sequences. The end groups of the copolyperoxides have been identified by ¹H NMR as well as FTIR spectroscopic techniques. The thermal degradation of the copolyperoxides has been studied by differential scanning calorimetry, which confirms the alternating peroxide units in the copolyperoxide chain.