Lyotropic liquid crystal self-assembly of H2O2-hydrolyzed chitin nanocrystals
Lyotropic liquid crystal self-assembly of H2O2-hydrolyzed chitin nanocrystals
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H2O2水解甲壳素纳米晶的溶致液晶自组装
DOI：
10.1016/j.carbpol.2018.04.098
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发表时间：
2018
影响因子：
11.2
通讯作者：
Huang Yifeng
中科院分区：
文献类型：
--
作者：
Liu Dagang;Chang Yu;Tian Donglin;Wu Wenqi;Lu Ang;Prempeh Nana;Tan Meijuan;Huang Yifeng
利用h2o2水解机械去纤的几丁质纳米原纤维，探索了一种制备平均长度为350 nm，宽度为40 nm的棒状几丁质纳米晶体（h2o2水解CHNs）的绿色方法。我们研究了chn的结构和形态，以及其胶体分散体的流变学和溶性自组装行为。结果表明，h2o2水解的chn虽然保持了α-几丁质的晶体结构，但表面电荷由正电荷转换为负电荷。因此，胶体纳米晶体在中性或碱性水介质中分散良好，并在两个临界浓度之间表现为溶致液晶。有趣的是，溶致液晶转变是由排列良好的纳米纤维自发自组装到纳米带和多层片的过程。在较高的临界浓度下，h2o2水解的CHN胶体呈现出溶胶-凝胶转变，这种转变高度依赖于储存时间、浓度、温度和表面电荷密度。通过提高CHNs的表面电荷密度或降低老化温度和胶体浓度，可以有效地维持向列相而不是凝胶相。
H2O2hydrolysis of mechanically-defibrillated chitin nanofibrils was explored as a green way of fabricating rod-like chitin nanocrystals (H2O2-hydrolyzed CHNs) that have an average length of 350 nm and width of 40 nm. We investigated the structure and morphology of CHNs as well as the rheology and lyotropic self-assembly behavior of its colloidal dispersions. The results show that although H2O2-hydrolyzed CHNs maintained the crystalline structure of α-chitin, surface charge of the nanorods was switched from positive to negative. As a consequence, the colloidal nanocrystals were well-dispersed in neutral or alkaline aqueous media, and behaved as a lyotropic liquid crystal between two critical concentrations. It is interesting that lyotropic liquid crystal transition was a spontaneously self-assembly from well-aligned nanofibers, to nanobelts, and to multi-layered lamellae. At high critical concentration, H2O2-hydrolyzed CHN colloids exhibited a sol-gel transition, which was discovered to be highly dependent on the storage time, concentration, temperature, and surface charge density. It is also suggested that nematic mesophases rather than gel could be effectively maintained by improving the surface charge density or lowering the aging temperature and colloidal concentration of CHNs.