Rdeactions in polymer blends: interchain effects and theoretical problems

摘要

Advances in experimental and theoretical studies of peculiarities of the reactions in polymer blends are reviewed. Experimentalists involve in the studies some relatively simple model systems such as homogeneous and quasi-homogeneous melts, as well as bilayer or trilayer films with well-defined interfaces. Such systems enavble one to determine the kinetic parameters of the reaction, to estimate relative contributions of the reactivity and diffusion in the reaction kinetics, to elucidate some peculiarities of the reaction at the interface, etc. Experimental studies of the reactions in the model systems stimulate a formulation of appropriate theoretical problems, an analysis of the reactions in the model systems stimulate a formulation of appropriate theoretical problems, an analysis of the interchain interactions being the key approach in a creation of the corresponding theoretical models. The achievements related to different kinds of reactions are considered. For polymer-analyogous reaction, the evolution of the blend structure under concerted action of the reaction and interdiffusion has been first described. For end-coupling reaction, the reaction kinetics both in a homo-geneous melt and in the interface is described. An influence of the diblock copolymer formed both on the reaction kinetics and on the thermodynamic equilibrium is analyzed. Theoretical models account for the interchain interactions between the block copolymer and homopolymers and analyze such phenomena as segregatio of a copolymer to the interface leading to the significant change in the interface properties and the blend stability. For interchain exchange reaction proceeding in a homogeneous melt, an analytical description of the molecular weight and block length transient distributions of the reaction product is developed. Also the reaction in a heterogeneous blend is described using Monte Carlo simulation. Some important unsolved problems are mentioned.