Phase-Separated Interpenetrating Polymer Networks

Description

The key physicochemical problems of the formation and properties of interpenetrating polymer networks (IPNs) are considered. The main feature that determines the structure and properties of IPNs consists of the thermodynamic incompatibility of two constituents that arises in the course of the chemical reactions leading to the formation of IPNs. The peculiarities of the chemical reactions of IPN formation are the dependence of the reaction rate of the formation of each network on the presence of another. The chemical reactions are accompanied by the processes of phase separation. The conditions of the phase separation (its rate and degree) are dependent on the chemical kinetics. The heterogeneous structure (two evolved phases and the interfacial region between them) and the thermophysical, viscoelastic, and other physical properties of phase-separated IPNs are governed by the degree of segregation of the system into two phases. The formation of IPNs proceeds under conditions of superposition of the chemical kinetics of two reactions and the physical kinetics of phase separation, both proceeding in nonequilibrium conditions. The result is incomplete phase separation and a lack of interpenetration over the entire volume of the system.