Solvent-Vapor Induced Spherulitic Growth in Multicomponent Elastic Films

Abstract

Herein we study isothermal spherulitic crystallization in multicomponent thin films under solvent-vapor annealing. Spherulitic crystallization is taken as a coherent phase transition between an amorphous phase and a crystalline phase. Both of the two phases of the film are modeled as (possibly prestressed) elastic solids, and no a priori assumption is made on the stresses in the two phases. The interface between the two bulk phases is treated as an evolving one-dimensional open thermodynamic system defined by various thermodynamic variables. In particular, each chemical component of the interface is generally endowed with a mass density and a chemical potential. The interface, as a continuum system, is composed of particles. We assign each particle of an evolving interface a well-defined interface velocity so that a moving interface with mass density carries linear momentum and kinetic energy. By appealing to free energy imbalance for isothermal processes and balance of mass and momentum, we derive dissipation inequalities for the bulk phases and for the interface, with which we obtain constitutive restrictions through the Coleman–Noll procedure. The driving force behind spherulitic crystallization is identified as the quantity conjugate to the normal velocity in the interfacial dissipation inequality. Finally we investigate the effect of prestress on the directional dependence of spherulitic growth.