Abstract
We have reported that multifunctional hyperbranched polymers are synthesized by radical homopolymerization of ethylene glycol dimethacrylate in the presence of methyl (2-bromomethyl)acrylate as an addition-fragmentation chain transfer agent. The hyperbranched polymers contain the pendant vinyl groups and the ω-end vinyl groups, and exhibit thermosetting properties in the absence of any catalyst. In this study, the initiation mechanisms for the thermal curing of the hyperbranched polymer were investigated by radical trapping using a nitroxide free radical. The hyperbranched polymer reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxy benzoate by heating at 150 °C showing that the curing proceeded by radical mechanism. The 1H NMR analysis of the product revealed that the cleavage of Br－CH2 bond and C －C bond adjacent to a vinyl group having relatively low bond dissociation energies has minor contribution to the radical formation and thermal curing proceeds by spontaneous polymerization of vinyl groups.
