State Diagram of Phase Transition Temperatures and Solvent-Induced Recovery Behavior of Shape-Memory Polymer

In this study we analyzed the phase and state transitions of shape-memory polymers (SMPs)/solvent mixtures using the Flory-Huggins (FH) theory by extension of Vrentas and the Couchman-Karasz theory for glass transition, as well as Clausius-Clapeyron relation for melting transition. Using scaling relations of model parameters, we have obtained a theoretical prediction of state diagrams of the phase transition temperature and solvent-induced recovery in SMPs. The inductive decrease in transition temperature is identified as the driving force for the solvent-induced shape-memory effect in SMPs Consequently, the thermodynamics of the polymer solution and the relaxation theory were employed to characterize the dependencies of shape recovery time on the FH parameter and the ratio of the molar volume of solute to solvent. With the estimated model parameters, we constructed the state diagram for SMP, which provides a powerful tool for design and analysis of phase transition temperatures and solvent-induced recovery. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2896-2904, 2013