State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China.
J Agric Food Chem. 2011 Jan 26;59(2):570-6. doi: 10.1021/jf1036239. Epub 2010 Dec 17.
In this article, a facile, rapid, and efficient method was developed for the preparation of carboxymethyl hemicelluloses using microwave-induced organic reaction enhancement chemistry. The influences of the factors including reaction time, temperature, and the amount of sodium monochloroacetate and sodium hydroxide on the degree of substitution (DS) of the products were investigated. The rheological properties and the chemical structure of the resulting polymers were also studied. It was found that microwave irradiation could significantly promote the chemical reaction efficiency and accelerate the carboxymethylation of hemicelluloses with sodium monochloroacetate. Therefore, carboxymethyl hemicelluloses with higher DS of 1.02 could be obtained in much shorter time scales as compared to the conventional heating method. Results from rheological analysis indicated that carboxymethyl hemicellulose solutions exhibited shear-thinning behavior in the range of shear rates tested and showed lower viscosity and modulus in comparison with those of the native hemicelluloses due to lower molecular weight and the role of carboxymethyl groups in reducing the entanglements between hemicelluloses chains.
本文采用微波诱导有机反应强化化学的方法，开发了一种简便、快速、高效的制备羧甲基半纤维素的方法。考察了反应时间、温度、以及一氯乙酸钠和氢氧化钠用量等因素对产物取代度（DS）的影响。还研究了所得聚合物的流变性和化学结构。结果表明，微波辐射能显著提高化学反应效率，加速半纤维素与一氯乙酸钠的羧甲基化反应。因此，与传统加热法相比，可在更短的时间内获得取代度高达 1.02 的羧甲基半纤维素。流变分析结果表明，羧甲基半纤维素溶液在测试的剪切速率范围内表现出剪切变稀行为，由于分子量降低和羧甲基基团在减少半纤维素链之间缠结方面的作用，其粘度和模量均低于天然半纤维素。
