Formation of cellulose-carbene complex via depolymerization in ILs: Dependence of IL types on kinetics, conformation and dispersity.
Formation of cellulose-carbene complex via depolymerization in ILs: Dependence of IL types on kinetics, conformation and dispersity.
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通过在 IL 中解聚形成纤维素-卡宾复合物：IL 类型对动力学、构象和分散性的依赖性。
DOI：
10.1016/j.carbpol.2016.12.022
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发表时间：
2017
影响因子：
11.2
通讯作者：
S. Kwak
中科院分区：
文献类型：
--
作者：
Yongjun Ahn;Younghan Song;Hyungsup Kim;S. Kwak
研究了阴离子种类对纤维素解聚的影响，以及阴离子种类对纤维素分子状态、动力学和分散性的影响。GPC和货车Gurp-Palmen图显示，与1-丁基-3-甲基咪唑鎓乙酸盐（[C4 C1 Im][OAc]）相比，1-丁基-3-甲基咪唑鎓氯化物（[C4 C1 Im][Cl]）更显著地降低摩尔质量。采用碱滴定法，以电导率和pH值为监测指标，证明了离子液体中纤维素的酸催化水解。与解聚情况相反，[C4 C1 Im][OAM]溶液比[C4 C1 Im][Cl]溶液需要更多的碱来中和。生成的卡宾与纤维素的还原末端结合，这在由大量还原末端组成的低摩尔质量中是有利的。纤维素-卡宾取代的形成引起纤维素链的空间位阻，从而导致高分子密度下链段摩擦增加。与卡宾结合的纤维素颗粒可以稳定地分散在水介质中。
This study focused on the influence of anion type on the depolymerization and its effect on the molecular state, dynamics and dispersity of cellulose. GPC and the van Gurp-Palmen plot showed that molar mass was more significantly decreased by 1-butyl-3-methylimidazolium chloride ([C4C1Im][Cl]) comparing to 1-butyl-3-methylimidazolium acetate ([C4C1Im][OAc]). Acid-catalyzed hydrolysis of cellulose in IL was proved using base titration which was monitored by conductivity and pH value. On the contrary to the depolymerization case, [C4C1Im][OAc] solution needed more base to be neutralized than [C4C1Im][Cl] solution. The generated carbene was combined with reducing ends of cellulose, which was facilitated in low molar mass consisting of a large number of reducing ends. The formation of cellulose-carbene substitution caused steric hindrance of cellulose chain, thus resulting in increased segmental friction with high molecular density. The cellulose particle combined with carbene can be dispersed stably in aqueous media.