Monovalent Salt and pH-Induced Gelation of Oxidised Cellulose Nanofibrils and Starch Networks: Combining Rheology and Small-Angle X-ray Scattering.
Monovalent Salt and pH-Induced Gelation of Oxidised Cellulose Nanofibrils and Starch Networks: Combining Rheology and Small-Angle X-ray Scattering.
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DOI：
10.3390/polym13060951
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发表时间：
2021-03-19
期刊：
影响因子：
5
通讯作者：
Edler KJ
中科院分区：
文献类型：
--
作者：
Hossain KMZ;Calabrese V;da Silva MA;Bryant SJ;Schmitt J;Ahn-Jarvis JH;Warren FJ;Khimyak YZ;Scott JL;Edler KJ
水质参数，如含盐量和不同的pH环境，会改变凝胶的稳定性及其流变性。在这里，我们研究了不同浓度的氯化钠和不同的pH环境对氧化纤维素纳米纤维(OCNF)和淀粉基水凝胶的流变性的影响。氯化钠的加入增加了OCNF：淀粉(1：1wt%)共混凝胶的硬度，其中盐在减少OCNF纤维相互作用方面发挥了重要作用。这些水凝胶的流变性在pH 5.0~9.0范围内保持不变。然而，在较低的pH(4.0)下，由于质子诱导的纤维相互作用，OCNF和OCNF：淀粉凝胶的硬度和粘度似乎增加。相反，在较高的pH(11.5)下，由于形成了更密集的聚集的凝胶网络，观察到了脱水现象。通过ζ电位测量研究了这些水凝胶的相互作用和聚集行为。此外，用小角X射线散射(SAXS)研究了OCNF凝胶的纳米结构，结果表明，由于纤维表面电荷的屏蔽，随着盐浓度的增加，OCNF凝胶在低Q区的斜率增加。
Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. The rheological properties of these hydrogels were unchanged at pH 5.0 to 9.0. However, at lower pH (4.0), the stiffness and viscosity of the OCNF and OCNF:starch gels appeared to increase due to proton-induced fibrillar interactions. In contrast, at higher pH (11.5), syneresis was observed due to the formation of denser and aggregated gel networks. Interactions as well as aggregation behaviour of these hydrogels were explored via ζ-potential measurements. Furthermore, the nanostructure of the OCNF gels was probed using small-angle X-ray scattering (SAXS), where the SAXS patterns showed an increase of slope in the low-q region with increasing salt concentration arising from aggregation due to the screening of the surface charge of the fibrils.
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