Grazing Incidence X-Ray Scattering For Monitoring Semi-Crystalline Polymer Dissolution, Recrystallization, and Morphology Mechanisms with Solvent Vapor Treatment*

Poly(ε-caprolactone) (PCL) is a semicrystalline, biodegradable polyester predominantly used in biomedical engineering applications as a tissue scaffold and a drug delivery medium. Degree of crystallinity, crystal morphology, and crystallite size are known to affect degradation rates of PCL fibers and films, so morphological control is important in designing PCL materials for its applications. Inspired by the use of solvent vapor annealing (SVA) to control block copolymer morphology and solvent-induced crystallization in semicrystalline polymers, we are studying how SVA impacts PCL crystallization and its morphology. Prior studies have focused on the roles of solvent choice, extent of film swelling, and solvent evaporation rate on the final film morphology. Herein, we apply grazing incidence X-ray scattering techniques in situ to probe the mechanisms of polymer dissolution during solvent uptake and recrystallization behavior during solvent removal aiming to understand why we observe new morphologies in semicrystalline PCL thin films.