Department of Material Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Republic of Korea.
Carbohydr Polym. 2017 Mar 1;159:86-93. doi: 10.1016/j.carbpol.2016.12.022. Epub 2016 Dec 8.
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 ([CCIm][Cl]) comparing to 1-butyl-3-methylimidazolium acetate ([CCIm][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, [CCIm][OAc] solution needed more base to be neutralized than [CCIm][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.
本研究重点关注了阴离子类型对纤维素解聚的影响及其对纤维素分子状态、动力学和分散性的影响。GPC 和 van Gurp-Palmen 图表明，与 1-丁基-3-甲基咪唑氯 ([CCIm][Cl]) 相比，[CCIm][OAc]（1-丁基-3-甲基咪唑乙酸盐）更显著地降低了摩尔质量。通过电导率和 pH 值监测的碱滴定证明了在离子液体中纤维素的酸催化水解。与解聚情况相反，[CCIm][OAc] 溶液需要更多的碱来中和，而 [CCIm][Cl] 溶液则不需要。生成的卡宾与纤维素的还原端结合，在低摩尔质量、大量还原端组成的情况下，这更容易发生。纤维素-卡宾取代物的形成导致纤维素链的空间位阻，从而导致高分子密度下的链段摩擦增加。与卡宾结合的纤维素颗粒可以在水介质中稳定分散。
