Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 2G2, Canada; Department of Chemistry, Wuhan University, Wuhan, 430072, China.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada.
Carbohydr Polym. 2014 May 25;105:214-21. doi: 10.1016/j.carbpol.2014.01.077. Epub 2014 Jan 31.
The sol-gel transition in the mixture system of oppositely charged polyelectrolyte (quaternized hydroxyethylcellulose ethoxylate, QHEC) and nanocrystalline cellulose (NCC) induced by electrostatic adsorption interaction was investigated by rheological means. Winter and Chambon theory was validated to be applicable for the critical gel point determination, and critical gel point have been successfully determined. With QHEC concentration increasing, more NCC were needed to form a critical gel, and smaller loss tangent and relaxation exponent (n) values at the gel point were observed, indicating the elastic nature of mixture was enhanced with QHEC increase. Gel strength behaved as a function of both QHEC and NCC concentrations, suggesting the gel network at the critical point was composed of entanglements and association of QHEC macromolecular chains, as well as the electrostatic adsorption interaction between QHEC chains and NCC rods. The calculated number of NCC rods per junction decreased from 0.30 to 0.01 when the QHEC concentration increased from 1.0wt% to 3.0wt%, indicating the electrostatic adsorption interaction between the NCC rods and QHEC chains was less significant to gel formation at higher QHEC concentrations. Therefore, the exponents of scaling law η0∝ϵ(-γ) and Ge∝ϵ (z) for the QHEC/NCC mixtures revealed that the scaling law n=z/(z+γ) between n, γ, and z was only feasible at highest QHEC concentration, since the intermolecular interaction (electrostatic adsorption interaction in this article) was so weak that can be neglected and the critical gel network was dominated by QHEC chain entanglements and association.
通过流变学方法研究了带相反电荷的聚电解质（季羟乙基纤维素乙氧基化物，QHEC）与纳米纤维素（NCC）混合物体系在静电吸附相互作用下的溶胶-凝胶转变。验证了 Winter 和 Chambon 理论适用于临界凝胶点的确定，并成功地确定了临界凝胶点。随着 QHEC 浓度的增加，形成临界凝胶需要更多的 NCC，并且在凝胶点处观察到较小的损耗角正切和松弛指数（n）值，表明混合物的弹性随着 QHEC 的增加而增强。凝胶强度表现为 QHEC 和 NCC 浓度的函数，表明在临界点处的凝胶网络由 QHEC 大分子链的缠结和缔合以及 QHEC 链与 NCC 棒之间的静电吸附相互作用组成。当 QHEC 浓度从 1.0wt%增加到 3.0wt%时，每个交联点的 NCC 棒数从 0.30 减少到 0.01，表明在较高的 QHEC 浓度下，NCC 棒与 QHEC 链之间的静电吸附相互作用对凝胶形成的影响较小。因此，QHEC/NCC 混合物的η0∝ϵ(-γ)和 Ge∝ϵ (z)的标度律指数表明，n、γ和 z 之间的标度律 n=z/(z+γ)仅在最高 QHEC 浓度下才可行，因为分子间相互作用（本文中的静电吸附相互作用）很弱，可以忽略不计，并且临界凝胶网络主要由 QHEC 链缠结和缔合组成。
