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Infrared Spectroscopy and X‐Ray Diffraction Studies of CH…O Hydrogen Bonding and Thermal Behavior of Biodegradable Poly(hydroxyalkanoate)
Author(s) -
Sato Harumi,
Murakami Rumi,
Zhang Jianming,
Mori Katsuhito,
Takahashi Isao,
Terauchi Hikaru,
Noda Isao,
Ozaki Yukihiro
Publication year - 2005
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200551155
Subject(s) - infrared spectroscopy , crystallography , x ray crystallography , hydrogen bond , intermolecular force , crystal structure , chemistry , infrared , lattice constant , materials science , amorphous solid , diffraction , molecule , optics , organic chemistry , physics
Infrared (IR) spectra and wide‐angle X‐ray diffraction (WAXD) patterns of poly(3‐hydroxybutyrate) (PHB) and its copolyester, poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyhexanoate), P(HB‐ co ‐HHx) (HHx = 12 mol%) were measured over a temperature range of 20 °C to higher temperatures (PHB, 185 °C, HHx = 12 mol%, 140 °C) to explore their structure change and thermal behavior and molecular interaction. The WAXD measurements revealed that the a lattice parameter increases significantly with temperature, while the b lattice parameter varies a little in the crystalline PHB and P(HB‐ co ‐HHx). It seems that the intermolecular interaction between the CO group of one helical structure and the CH 3 group of the other helical structure decreases along the a axis of crystalline PHB and P(HB‐ co ‐HHx) with temperature. The temperature‐dependent IR spectral variations were analyzed for the CH stretching, CO stretching, CH 3 deformation, and COC stretching variation regions, and bands characteristic of crystalline and amorphous parts were identified in each region. It was found from the anomalous frequencies of the CH 3 asymmetric stretching and CO stretching bands of PHB and P(HB‐ co ‐HHx) and the X‐ray crystallographic structure of PHB that there is an intermolecular interaction (CH…OC hydrogen bond) between the CO group and the CH 3 group combining two helical structures in PHB and P(HB‐ co ‐HHx). In this review paper we discuss the role of the CH…OC hydrogen bonding and the crystal and lamella structure of PHB and P(HB‐ co ‐HHx) (HHx = 12 mol %) in comparison with the structure of Nylon.