小角X射线散射
化学工程
聚合物
材料科学
聚乙二醇
扫描电子显微镜
水溶液
胶体
蒸发
PEG比率
粒子(生态学)
结晶学
化学
散射
有机化学
光学
复合材料
工程类
经济
地质学
物理
海洋学
热力学
财务
作者
Maoqi Lin,Vikram Singh Raghuwanshi,Christine Browne,George P Simon,Gil Garnier
标识
DOI:10.1016/j.jcis.2021.12.182
摘要
The conditions to allow self-assembly of cellulose nanocrystal (CNC) suspensions into chiral nematic structures are based on aspect ratio, surface charge density and a balance between repulsive and attractive forces between CNC particles.Three types of systems were characterized in suspensions and subsequently in their solid dried films: 1) neat water dialyzed CNC, 2) CNC combined with polyethylene glycol(PEG) (CNC/PEG), and 3) CNC with added salt (CNC/Salt). All suspensions were characterized by polarized optical microscope (POM) and small angle X-ray scattering (SAXS), while the resultant dried films were analyzed by reflectance spectrometer, scanning electron microscope (SEM) and SAXS.The presence of chiral nematic (CN*) structures was not observed in dialyzed aqueous suspensions of CNC during water evaporation. By introducing salts or a non-adsorbing polymer, chirality was apparent in both suspensions and films. The interaxial angle between CNC rods increased when the suspensions of CNC/PEG and CNC/salt were dried to solid films. The angle was found to be dependent on both species of ions and ionic strength, while the inter-particle distance was only related to the salt concentration, as explained in terms of interaction energies. The CNC suspensions/film chirality can be modulated by controlling the colloidal forces.
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