Dispersion stability and aggregation behavior of TEMPO-oxidized cellulose nanofibrils in water as a function of salt addition
Dispersion stability and aggregation behavior of TEMPO-oxidized cellulose nanofibrils in water as a function of salt addition
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DOI：
10.1007/s10570-014-0180-z
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发表时间：
2014-06-01
期刊：
影响因子：
5.7
通讯作者：
Isogai, Akira
中科院分区：
文献类型：
--
作者：
Fukuzumi, Hayaka;Tanaka, Reina;Isogai, Akira
通过实验和理论分析研究了TEMPO氧化纤维素纳米纤丝（TOCN）在水中的分散稳定性，以阐明不同盐的临界聚集浓度。通过测量透光率、稳定剪切流下的粘度和聚集的TOCN的重量分数来评价具有各种NaCl浓度的0.1重量% TOCN/水分散体。均匀的TOCN/水分散体变成凝胶NaCl浓度的增加。TOCN分散体保持其均匀状态高达50 mM NaCl，但聚集的凝胶颗粒形成在100 mM NaCl。在千分之一的200 mM NaCl下，混合物分离成两相（凝胶和上清液）。理论分析表明，基于Derjaguin-Landau-Verwey-Overbeek理论的两圆柱杆间的相互作用势能可以很好地解释加入NaCl后的聚集行为。将实验扩展到分析0.1重量% TOCN分散体的MgCl 2和CaCl 2的临界聚集浓度。在二价电解质的情况下，TOCN元素在2-4 mM的盐浓度下开始形成聚集的凝胶颗粒，对应于由经验Schultz-Hardy规则预测的临界聚集浓度。
Dispersion stability of TEMPO-oxidized cellulose nanofibrils (TOCNs) in water was investigated through both experimental and theoretical analyses to elucidate the critical aggregation concentration of different salts. The 0.1 wt% TOCN/water dispersions with various NaCl concentrations were evaluated by measuring light transmittance, viscosity under steady-shear flow, and the weight fraction of TOCN that had aggregated. Homogeneous TOCN/water dispersion turned to gel as the NaCl concentration increased. The TOCN dispersion maintained its homogeneous state up to 50 mM NaCl, but aggregated gel particles were formed at 100 mM NaCl. The mixture became separated into two phases (gel and supernatant) at a parts per thousand yen200 mM NaCl. Theoretical analysis using zeta-potentials of TOCN elements in the dispersions revealed that the aggregation behavior upon NaCl addition could be explained well in terms of the interaction potential energy between two cylindrical rods based on the Derjaguin-Landau-Verwey-Overbeek theory. The experiments were extended to analyze critical aggregation concentrations of MgCl2 and CaCl2 for the 0.1 wt% TOCN dispersion. In the case of divalent electrolytes, TOCN elements began to form aggregated gel particles at salt concentrations of 2-4 mM, corresponding to the critical aggregation concentration predicted by the empirical Schultz-Hardy rule.