Transitions of morphological patterns of crystallizing polycarbonate in thin films

This article reports the transitions of morphological patterns of polycarbonate crystals in thin films by solvent‐induced crystallization (SINC). As a substrate (silica glass) deposited with an amorphous and micron‐thick bisphenol A polycarbonate polymer film is partially dipped into a liquid acetone bath, acetone penetrated rapidly through the polymer film. The rate of acetone penetration is significantly higher than the predicted by Fickian diffusion or anomalous diffusion model, indicating that the capillary force through stress‐induced cracks may have played a major role in the upward transport of acetone through the polymer films. The morphologies of polycarbonate at different vertical positions on a substrate surface were analyzed by scanning electron microscopy and atomic force microscopy. It was observed that depending on the local acetone concentration the polymer morphologies showed quite diverse patterns ranging from stress‐induced cracks to fully developed three‐dimensional spherulites. The diverse morphologies developed during the thin film SINC may serve as a useful platform for further detailed mechanistic analysis of structures and crystallization kinetics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012