基于分子修饰C-COS的高吸湿保湿机理

The High Moisture-absorption and Moisture-retention Mechanism of Molecularly Modified C-COS

摘要:

采用漆酶/2,2,6,6-四甲基哌啶-1-氧自由基（TEMPO）体系氧化壳寡糖制备了一种高吸湿保湿性羧基化壳寡糖（C-COS）。利用低场核磁共振（LF-NMR）、FTIR和13CNMR研究其分子间氢键的变化进一步推测出吸湿保湿机理。结果表明：在C-COS的吸湿过程中，聚合物分子与水之间存在着分子间氢键作用力。C-COS分子上极性较强的羧酸根产生了新的氢键效应，结合升温红外中3363、1643 cm-1处吸收峰强度的减小和同样波数下吸收峰频率的蓝移以及溶胀红外中1643 cm-1处吸收峰强度的增加，确定了C-COS分子中羧酸根与水之间所形成的水合氢键（H-O-H•••O-C=O）。另外，C-COS的保湿机理在于聚合物溶解在水体系中能够形成一种巨大的聚合物-水网状结构，促使水分子以氢键的形式被牢牢地锁住在这种网状结构中。

Abstract:

Carboxylated-chitooligomer (C-COS), which had a high moisture-absorption and moisture-retention ability, was prepared by oxidation of chitooligomer using a laccase/ 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system. The intermolecular hydrogen bonding of C-COS was investigated by low-field nuclear magnetic resonance (LF-NMR), FTIR and 13CNMR, and its moisture-absorption and moisture-retention mechanism was deduced. The results showed that intermolecular hydrogen bonding were formed between polymer molecules and water in the course of C-COS hygroscopic process. More polar carboxylate ions on the C-COS molecule produced new hydrogen bonding effect. The decrease of the absorption peak intensity at 3363 and 1643 cm-1 and blue shift of the absorption frequency at the same wave number in the heating IR, as well as the increase of the absorption peak at 1643 cm-1 in the swelling IR, confirming that information of hydrated hydrogen bonds (H-O-H•••O-C=O) between water and carboxylate ions on the C-COS molecule. In addition, moisture-retention mechanism of C-COS was obtained that the polymer dissolved in the water system can form a huge polymer-water network structure, prompting the water molecule in the form of hydrogen bonds was firmly locked in this network structure.