(705b) Thin Film Crystallization and Morphology of Poly(ε-caprolactone)

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. By combining a flow coating technique to generate gradient thickness films and automated atomic force microscopy imaging, we are able to rapidly characterize morphology transitions as a function of film thickness. These transitions are driven by the reorientation of crystalline lamellae under thin film confinement. Initial studies examined these morphological transitions for several molecular weights of linear PCL in an effort to connect transition film thicknesses to molecular length scales. Subsequently, we blended PCL with a block copolymer and identified previously unreported novel crystal morphologies that result from the block copolymer directing and confining the crystallization of PCL during film casting. Our results show that thin film and molecular level confinement can be used to control crystallization and morphology in semi-crystalline polymer films making these materials tailorable for specific applications.