Solvent Vapor Annealing to Control Polymer Crystal Morphology*

Poly(ε-caprolactone) (PCL) is a semi-crystalline, hydrophobic, biodegradable polymer that has found uses in the packaging industry and in biomedical engineering as an anti-adhesion biomaterial film and drug delivery medium among other applications. 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 for these applications. Inspired by the literature related to solvent vapor annealing (SVA) in block copolymer films and solvent-induced crystallization in semi-crystalline polymers, we are studying how SVA treatments impact crystal morphology. We use in-situ grazing incidence wide-angle X-ray scattering to determine when/if polymer crystals dissolve during solvent uptake and at what solvent concentrations recrystallization occurs during solvent removal. Additionally, we examine polymer morphology across multiple length scales using a combination of optical microscopy, profilometry, and atomic force microscopy.