Dimensions of Large-Sized Network Polymers Formed in Miniemulsion Polymerization

Abstract

The mean-square radius of gyration of network polymers can be correlated with the graph diameter, and the fraction d of segments located in the diameter chain is used to investigate the dimensions of large-sized network polymers whose cycle rank is over 10³. A simplified Monte Carlo simulation model for the miniemulsion vinyl/divinyl copolymerization is used for the generation of large-sized network polymers, assuming the classical chemical kinetics are valid. Both conventional free-radical polymerization and living polymerization are considered, and the heterogeneity of network architecture is controlled by changing the reactivity ratio of double bond in divinyl monomer with respect to that in vinyl monomer. The network maturity index (NMI) which is the cycle rank per primary chain is used to represent the degree of development of the network architecture. As the NMI increases to be well-developed, the calibrated d, defined by d_c = d/f_d where f_d is a calibration constant that shows the degree of network heterogeneity, starts to follow the master curve. This characteristic behavior applies regardless of the polymerization mechanism and the heterogeneity of the formed network architecture. Detailed characteristics of the master curve and prospects for application to gel molecules are also discussed.