Monte Carlo simulation of the direct exchange reaction in a polymer blend

The reaction of direct interchain exchange in a homogeneous blend of linear polymers was modeled numerically using the Monte Carlo method. The evolution of the molecular-mass and block-mass distributions was studied for the two types of initial conditions: a blend of two polymers with the Flory distribution and a blend of monodisperse polymers. In the course of the reaction, the molecular-mass distribution relaxes to the total Flory distribution, whereas the evolution of the block-mass distribution to the Bernoulli distribution is considerably slower. The evolution of the block-mass distribution was studied for the first time. At early stages of the reaction, the copolymer (product) composition can differ substantially from the composition of the blend as a whole. The transient molecular-mass distributions obtained by the Monte Carlo method agree well with the results of theoretical calculations.