期刊
NORDIC PULP & PAPER RESEARCH JOURNAL
卷 29, 期 1, 页码 46-57出版社
WALTER DE GRUYTER GMBH
DOI: 10.3183/npprj-2014-29-01-p046-057
关键词
Cellulose nanocrystals; Surface modification; Surfactant Adsorption; Quaternary ammonium surfactant; Cetyltrimethylammonium Bromide; CTAB; Ethanol
Cellulose nanocrystals (CNCs) prepared by sulfuric acid hydrolysis of cotton were surface modified with cetyltrimethylammonium bromide (CTAB). Essentially, the counterions of the CNC surface sulfate ester groups are exchanged for cetyltrimethylammonium (CTA+), which acts as a bulky, amphiphilic cation. The CTAB-modified CNCs were thoroughly purified to remove surfactant that was non-electrostatically bound. The surface modification could be tailored from 50 to 100% charge coupling efficiency by varying the reaction conditions. The main factor that influenced coupling efficiency was ionic strength; increasing the ionic strength screened electrostatic interactions, which led to decreased surfactant adsorption. Adsorption isotherms of CTAB on model CNC films, measured by surface plasmon resonance spectroscopy, indicated an increase in adsorbed surfactant amount with increasing bulk CTAB concentration without achieving saturation in the concentration range studied. CTAB-modified CNCs were unstable in water but formed stable colloidal suspensions in ethanol, which transitioned into a continuous gel-like chiral nematic liquid crystal at relatively low concentrations (similar to 4 wt. %) but did not phase separate into isotropic and anisotropic phases. The particle size and morphology of the CTAB-modified CNCs were unchanged compared to the native CNCs but were more thermally stable and less hydrophilic after the surface modification reaction.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据