Brownian dynamics simulation of diffusion-limited polymerization of rodlike molecules: Isotropic translational diffusion

Abstract

Rigid rodlike polymers have considerable technological importance due to their excellent mechanical properties. The polymerization kinetics of such condensation polymers are qualitatively different from flexible polymers, and exhibit significant slowing at the later stages of the reaction. This is due to the slow rotational diffusion of the molecules to an appropriate configuration for reaction. In this work we have carried out Brownian dynamics (ED) simulations to obtain the effective rate constant for reaction between rodlike molecules in the presence of diffusional limitations. The theory of Northrup et nl. [J. Chem. Phys. 80, 1517 (1984)] for pairwise ED simulation of reactions is extended to the case of rodlike molecules assuming isotropic translational diffusion. The computed results are compared to exact analytical predictions. Good agreement between computation and theory is obtained over a wide range of parameter values. (C) 1997