Poly(ε-caprolactone) (PCL) is a semi-crystalline, hydrophobic, biodegradable polymer with applications in biomedical engineering including anti-adhesion biomaterial films, drug delivery media, and others. Degree of crystallinity, crystal morphology, and crystallite size are known to affect the biodegradation profile of PCL fibers and films by enzymes, so morphological control is important to designing PCL coatings and films. The Albert Lab manipulates semi-crystalline morphology in these films by leveraging control over processing conditions. This talk will focus on the group’s most recent work using solvent vapor annealing to control morphology. Exposure of PCL films exhibiting a typical spherulitic morphology (35-40% crystalline) to various solvent vapors results in partial dissolution of polymer crystallites and recrystallization of films into non-spherulitic morphologies upon solvent evaporation. These unconventional crystal structures have the same overall degree of crystallinity as the original spherulitic crystal structures but lack well-defined boundaries and interact with light differently. Through in-situ monitoring of film changes via spectral reflectance and structural changes by grazing-incidence X-ray scattering (wide- and small-angle) during solvent vapor annealing, we are constructing a mechanistic picture of film swelling crystal dissolution during solvent uptake as well as crystal nucleation and growth kinetics during solvent removal.