New aspects of unsaturated polyester resin synthesis. Part I: modelling and simulation of reactant sequence length distributions in stepwise polymerization

The quantification of the relationship between physical properties of polymeric products and the sequence distribution of comonomer units in a polymer chain is not an easy task. In this work, detailed consideration is given to the sequence lengths and sequence length distributions to be expected in unsaturated polyesters formed by the reaction of maleic anhydride, phthalic anhydride and a diol, a reaction which gives rise to the low molecular weight precursors used in unsaturated polyester resins. Monte Carlo methods are used to explore the effects of rate constants, reactant stoichiometry and extent of reaction on the microstructure of the chain. Attention is also given to structural asymmetry of the diol component and the influence of the dynamics of the ring opening of the anhydride coreactants on the products. The approach is generic and can be readily adapted for any copolymerization which proceeds by a stepwise kinetic mechanism. (C) 2003 Society of Chemical Industry.