Abstract
Semicrystalline films were prepared by casting chloroform (CHL), acetonitrile (ACN) or tetrahydrofuran (THF) solutions of a mixture (mix-poly(lactic acid) (PLA)) of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA). All of the films involve stereocomplex crystals (sc-PLA) of PLLA and PDLA, but no crystals of PLLA or PDLA. The origin of the marked cast-solvent dependence of the morphology was studied by assuming that the structure of sc-PLA would be constructed by the balance of the interaction energy E1 between the PLLA and PDLA chains in solution, and the interaction energy E2 between PLLA or PDLA chains and solvent molecules. With the relation between E1 and E2, the scheme for the formation of sc-PLA was classified into two categories, Category-I and -II. In Category-I, the relation E1>E2 holds over the entire concentration range, and in Category-II, the relation E1<E2 holds over the range from dilute to moderate concentrations. As a result, the data indicate that Category-I would be proper when sc-PLA is formed by casting a THF or ACN solution of mix-PLA, and that Category-II would be proper when sc-PLA is formed by casting the CHL solution of mix-PLA.
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Acknowledgements
Our deepest appreciation is given to Dr Kurita for valuable discussions and to Dr Igarashi and Dr Shimizu of the High Energy Accelerator Research Organization and Professor Suzuki and Dr Kurumi of Electrical Engineering, Nihon University, for technical support. We would also like to thank Creative Materials Research Center (Research Institute of Science & Technology, Nihon University) for the use of the analytical apparatus. This work was supported in part by Nihon University Strategic Projects for Academic Research, ‘Nanomaterial-based Photonic, Quantum and Bio Technologies.’
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Koide, Y., Ikake, H., Muroga, Y. et al. Effect of the cast-solvent on the morphology of cast films formed with a mixture of stereoisomeric poly(lactic acids). Polym J 45, 645–650 (2013). https://doi.org/10.1038/pj.2012.192
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DOI: https://doi.org/10.1038/pj.2012.192
