Absorption of water molecules on the surface of stereocomplex-crystal spherulites of polylactides: An in-situ FT-IR spectroscopy investigation

• Published in: Polymer (Guilford) Vol. 298; p. 126922
• Main Authors: Kokuzawa, Tomoka, Hirabayashi, Shunryu, Ikemoto, Yuka, Park, Junsu, Ikura, Ryohei, Takashima, Yoshinori, Higuchi, Yuji, Matsuba, Go
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 09-04-2024
• Subjects: Microbeam FT-IR spectroscopy; Microbeam X-ray diffraction; Polylactide; Microbeam X-ray diffraction; Microbeam FT-IR spectroscopy; Polylactide
• ISSN: 0032-3861
• DOI: 10.1016/j.polymer.2024.126922

The correlation between water molecules and polylactide was clarified. The crystallinity in stereocomplex (SC) crystal spherulites was investigated using microbeam wide-angle X-ray diffraction. The crystallinity was higher in the central region, and edge-on lamellae grew in a twisted manner. The hydrogen bonding in SC-crystal spherulites was evaluated via microbeam FT-IR spectroscopy in a humidity-controlled cell. The water-derived bands corresponding to OH vibration and HOH bending increased with increasing humidity. Microbeam FT-IR spectroscopy was used to evaluate the water absorption behavior of crystalline films depending on their position. Coarse-grained molecular dynamics simulations indicated that the number of adsorbed water molecules increased with decreasing crystallinity. In SC-crystal spherulites, water molecules are absorbed in both amorphous and crystalline regions but with greater difficulty in the crystalline regions. These insights into water molecule absorption on SC-crystal spherulite can facilitate the development of polylactide materials with controlled biodegradability for advanced medical and optical applications.
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•Water absorption on PLLA/PDLA blended films was investigated.•Interactions between water molecules and Sc-crystal spherulites were clarified.•The crystallinity of the spherulites was investigated using microbeam XRD.•Hydrogen bonding in spherulites was assessed by microbeam FT-IR spectroscopy.