Phase Transformation

Abstract

This article briefly summarizes some key theoretical concepts about phase transformations, discusses the extent, to which they differ from related phenomena in other materials, and mentions a few typical experiments to introduce the main techniques used to study such phase transitions. Phase transformations of polymeric materials, such as unmixing of polymer solutions or polymer blends, or the self‐assembly of copolymer materials into spatially modulated structures are very common phenomena and have important applications. This article focuses on the bulk thermodynamics, phase behavior and critical phenomena, interface and surface properties, and basic principles of structure formation (spinodal demixing and nucleation) in fluid polymer systems. Polymers in the solid state, that is, glassy or semicrystalline systems, rarely reach full thermal equilibrium and properties are history dependent. Such out‐of‐equilibrium aspects are beyond the scope of the present article, which rather emphasizes general aspects of the statistical thermodynamics of phase transitions and their applications to polymers in fluid phases.