Kinetics of ‘living’ radical polymerizations of multifunctional monomers

Abstract

The polymerizations of multifunctional monomers with an iniferter, p-xylylene bis-( N, N-diethyldithiocarbamate) (XDT), were studied with differential photocalorimetry. The iniferter was used to simulate a ‘living’ radical polymerization. The normal autoacceleration behavior that is often observed in the polymerization of multifunctional monomers was not evident in the reactions with the iniferter. The reversible reaction between the propagating polymer chain and the sulfur radical from the XDT molecule dominated the reaction and drastically decreased the rate of polymerization. Various parameters of the reaction (length between functional groups in the monomer, iniferter concentration, UV light intensity, and temperature) were investigated to determine the effect on the polymerization. The rate of polymerization and the final conversion of the polymer were increased significantly by increasing the temperature, initiator concentration and UV light intensity, and decreasing the length between functional groups. Mechanical properties of the resulting polymers were also examined. It was concluded that the presence of the iniferter during the polymerization of the multifunctional monomers had no effect on the heterogeneity of the polymer network. This was in agreement with previous modeling results.