Abstract
Morphological changes of macromolecularly porous thin films during isotactic (it) poly(methyl methacrylate) (PMMA) crystallization and the subsequent syndiotactic (st) poly(methacrylic acid) (PMAA) incorporation are described herein. Porous it-PMMA thin films were prepared on a gold substrate by the selective extraction of st-PMAA from stereocomplex films composed of it-PMMA/st-PMAA using layer-by-layer assembly. it-PMMA crystallization occurred when the porous it-PMMA films were immersed in a mixed solvent of acetonitrile/water (4/6, v/v). Surface analyses of films were performed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and static contact angles. Dotted aggregates of it-PMMA appeared on crystallized films, whereas networks composed of crystallized it-PMMA and the stereocomplex were observed on st-PMAA incorporated films. Gold substrate peaks were observed not on porous it-PMMA films, but on crystallized it-PMMA films by XPS, indicating that homogeneously broadened it-PMMA in porous films was localized because of its crystallization. The static contact angle of crystallized it-PMMA films was 36.5±1.6°, which was smaller than that of porous it-PMMA films (49.2±1.9°). This difference resulted from the surface morphology of the thin films. Dotted it-PMMA aggregates were also observed when spin-coated films were immersed in the mixed solvent.
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Acknowledgements
This work was partially supported by a Grant-in-Aid for Scientific Research (no.19650123) from the Japan Society of the Promotion of Science. We acknowledge Drs T Kida, J Watanabe, M Matsusaki, T Akagi, C Hongo, and T Waku, Osaka University, for their fruitful discussions.
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Kamei, D., Ajiro, H. & Akashi, M. Morphological changes of isotactic poly(methyl methacrylate) thin films via self-organization and stereocomplex formation. Polym J 42, 131–137 (2010). https://doi.org/10.1038/pj.2009.324
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DOI: https://doi.org/10.1038/pj.2009.324
