Carbohydrate Polymers ( IF 10.7 ) Pub Date : 2018-01-03 , DOI: 10.1016/j.carbpol.2018.01.010 Jinfeng Cao , Jun You , Lina Zhang , Jinping Zhou
The etherification of chitosan dissolved in aqueous LiOH/KOH/urea solutions was conducted for the first time. The structure and solution properties of the chitosan ethers were characterized using FT-IR, NMR, SEC-LLS, elemental analysis, and ζ-potential measurement. Chitosan ethers with different degrees of substitution (DSs) were obtained by adjusting the molar ratio of the etherifying agent to N-acetylglucosamine unit (AGU) of chitosan. The total DS for methyl chitosan (MCh) increased from 1.17 to 2.25, and trimethyl chitosan (TMCh) was obtained with DSN-trimethyl as high as 0.48. The total DS for carboxymethyl chitosan (CMCh) was in the range 0.75–1.45. Both N-substitution and O-substitution were observed, and the
OH groups at C-6 displayed relative higher reactivity than the
OH groups at C-3. In comparison with the traditional methods and solvents, aqueous alkali/urea solutions proved to be a stable and more homogeneous medium for preparing chitosan ethers with higher DS through a one-step reaction.
中文翻译：
在碱/脲水溶液中制备的壳聚糖醚的均相合成和表征
第一次进行溶解在LiOH / KOH /脲水溶液中的壳聚糖的醚化反应。使用FT-IR，NMR，SEC-LLS，元素分析和ζ电位测量对壳聚糖醚的结构和溶液性质进行了表征。通过调节醚化剂与壳聚糖的N-乙酰氨基葡糖胺单元（AGU）的摩尔比，可以得到具有不同取代度（DSs）的壳聚糖醚。甲基壳聚糖（MCh）的总DS从1.17增加到2.25，获得的三甲基壳聚糖（TMCh）的DS N-三甲基高达0.48。羧甲基壳聚糖（CMCh）的总DS在0.75–1.45的范围内。既Ñ 3'-取代和ö 3'-取代进行观察，并且
C-6的OH基团显示出相对较高的反应性C-3的OH基团。与传统方法和溶剂相比，碱/脲水溶液被证明是一种稳定的，更均匀的介质，可通过一步反应制备具有较高DS的壳聚糖醚。
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