Effect of steric hindrance on hydrogen-bonding interaction between polyesters and natural polyphenol catechin
✍ Scribed by Bo Zhu; Jianchun Li; Yong He; Hideki Yamane; Yoshiharu Kimura; Haruo Nishida; Yoshio Inoue
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 138 KB
- Volume
- 91
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Abstract
The phase behaviors for the blends of poly(3‐hydroxypropionate) (PHP), poly(L‐lactide) (PLLA), poly(D‐lactide) (PDLA), and poly(D,L‐lactide) (PDLLA) with catechin were investigated by differential scanning calorimetry. In PLLA/catechin, PDLA/catechin, and PDLLA/catechin blends, two glass transitions were detected when the catechin content was ≥40 wt %, whereas in PHP/catechin blends only one glass transition was observed over the whole range of blend compositions. The former and the latter results should reflect the inhomogeneous and the homogeneous nature of the blends, respectively, in the amorphous phase. These different phase behaviors should arise from the differences in the chemical structures between PHP and PLLA/PDLA/PDLLA, which dominates the strength and the number of intermolecular hydrogen‐bonding interactions between the ester carbonyl groups of polyesters and the phenol groups of catechin. As detected by FTIR spectroscopy, in comparison with PHP, the steric hindrance of side‐chain methyl groups of PLLA, PDLA, and PDLLA might restrain the formation of hydrogen bonds between their ester carbonyl groups and the phenol hydroxyl groups of catechin, even weakening the strength of such hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3565–3573, 2004