过硫酸铵一步氧化法制备羧基化纤维素纳米晶体及其胆甾型液晶  

Preparation of Carboxylated Cellulose Nanocrystals by One-step Oxidation of Ammonium Persulfate and Study on Their Cholesteric Liquid Crystals

作　　者：边开强 贺金涛 朴光哲[1,2] BIAN Kaiqiang;HE Jintao;PIAO Guangzhe(Key Laboratory of Rubber-Plastics,Ministry of Education,Qingdao University of Science and Technology,Qingdao 266042,China;College of Polymer Science and Engineering,Qingdao University of Science and Technology,Qingdao 266042,China)

机构地区：[1]青岛科技大学橡塑材料与工程教育部重点实验室,山东青岛266042 [2]青岛科技大学高分子科学与工程学院,山东青岛266042

出　　处：《青岛科技大学学报（自然科学版）》2020年第6期21-30,共10页Journal of Qingdao University of Science and Technology:Natural Science Edition

基　　金：科技部国际合作计划项目(2011DFA50430);国家自然科学基金项目(50773033).

摘　　要：羧基化纤维素纳米晶体悬浮液在达到临界浓度时可自组装形成胆甾型液晶(N*-LCs)。本工作首先探究了过硫酸铵(APS)一步氧化法的不同实验条件,结果表明制备APS氧化的纤维素纳米晶体(cellulose nanocrystals oxidized by APS, AOCNs)的最佳条件:微晶纤维素CF11与2 mol·L^(-1)的APS溶液按1 g∶100 mL的比例反应,反应温度60℃,反应时间16 h。制备的AOCNs的羧基含量为0.73 mmol·g^(-1),氧化度(DO)为0.12,平均粒径为144.5 nm,悬浮液的Zeta电位可达-40.5 mV。配制不同浓度的AOCNs悬浮液,分别置于比色皿中竖直静置一段时间,成功观察到了AOCNs的溶致N*-LCs所特有的指纹织构。研究结果表明:AOCNs悬浮液形成N*-LCs的临界浓度为4.1%(质量分数),其螺距(P)为15.6μm,并且随悬浮液浓度的增大,P减小。将浓度为5.3%(质量分数)的AOCNs悬浮液自然干燥,可以得到具有斑斓色彩的薄膜,并仍可观察到特征指纹织构,表明胆甾型结构得以保留。Carboxylated cellulose nanocrystals suspension can self-assemble to form cholesteric liquid crystals(N*-LCs) when reaches the critical concentration.Firstly, the experimental conditions of one-step oxidation by ammonium persulfate(APS) were investigated in this work. The results showed that the optimal conditions for the preparation of cellulose nanocrystals oxidized by APS(AOCNs) were as follows: Microcrystalline cellulose CF11 reacted with 2 mol·L-1 APS solution in a ratio of 1 g∶100 mL, and the reaction temperature was 60 ℃, reaction time was 16 h.And thecarboxyl content of the prepared AOCNs was 0.73 mmol·g-1, the oxidation degree was 0.12, the particle size was 144.5 nm, the Zeta potential of suspension was-40.5 mV. And the fingerprint texture unique to the lyotropic N*-LCs of AOCNs was successfully observed by preparing different concentrations of AOCNs suspensions and placing them in vertical standing cuvettes for a period of time.The research indicated that the critical concentration of AOCNs suspension to form lyotropic N*-LCs was 4.1%, and the pitch(P) of the N*-LCs was 15.6 μm, the P decreased as the suspension concentration increased in addition. Simultaneously, the 5.3% AOCNs suspension was naturally dried to obtain an iridescent film, and the characteristic fingerprint texture was still observed, indicating that the cholesteric structure was retained.

关 键 词：羧基化纤维素纳米晶体 胆甾型液晶 过硫酸铵 指纹织构 

分 类 号：TQ35[化学工程]