State Key Laboratory of Pulp and Paper Engineering, South China University of Technology , Guangzhou, China.
J Agric Food Chem. 2012 Feb 22;60(7):1695-702. doi: 10.1021/jf204522k. Epub 2012 Feb 9.
In this study, a novel amphoteric macromolecule was synthesized by sequential incorporation of carboxymethyl and quaternary ammonium groups into the backbone of xylan-type hemicelluloses under microwave irradiation. The reaction parameters such as the molar ratio of reagent (NaOH or 3-epoxypropyltrimethylammonium chloride)/anhydroxylose unit in hemicelluloses, the temperature, and the reaction time were investigated to optimize the reaction condition. The maximum degrees of substitution (DS) of carboxymethyl and quaternary ammonium groups under the optimum reaction condition were 0.90 and 0.52, respectively, exhibiting a higher efficiency as compared to the conventional heating method. Moreover, the thermal stability and weight-average molecular weight of amphoteric hemicellulosic derivatives decreased as compared to the native hemicelluloses. The viscosity, elastic modulus, and loss modulus of the amphoteric biomacromolecules increased with the increasing DS of quaternary ammonium groups in aqueous solution due to stronger electrostatic attraction. This study provides an efficient and rapid method to prepare amphoteric biomacromolecules.
在这项研究中，通过微波辐射，将羧甲基和季铵基团顺序引入木聚糖型半纤维素的主链中，合成了一种新型两性大分子。考察了反应参数，如试剂（NaOH 或 3-环氧丙基三甲基氯化铵）与半纤维素中无水糖单元的摩尔比、温度和反应时间，以优化反应条件。在最佳反应条件下，羧甲基和季铵基团的最大取代度（DS）分别为 0.90 和 0.52，与传统加热法相比，效率更高。此外，两性半纤维素衍生物的热稳定性和重均分子量均低于天然半纤维素。在水溶液中，由于静电吸引力增强，两性生物大分子的粘度、弹性模量和损耗模量随季铵基团 DS 的增加而增加。本研究为制备两性生物大分子提供了一种高效、快速的方法。
