College of Materials Science and Engineering, Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, Shenzhen University, Shenzhen 518055, China.
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518055, China.
Molecules. 2023 Jun 20;28(12):4868. doi: 10.3390/molecules28124868.
This study investigates the rheological properties of dual-network hydrogels based on acrylamide and sodium alginate under large deformations. The concentration of calcium ions affects the nonlinear behavior, and all gel samples exhibit strain hardening, shear thickening, and shear densification. The paper focuses on systematic variation of the alginate concentration-which serves as second network building blocks-and the Ca-concentration-which shows how strongly they are connected. The precursor solutions show a typical viscoelastic solution behavior depending on alginate content and pH. The gels are highly elastic solids with only relatively small viscoelastic components, i.e., their creep and creep recovery behavior are indicative of the solid state after only a very short time while the linear viscoelastic phase angles are very small. The onset of the nonlinear regime decreases significantly when closing the second network (alginate) upon adding Ca, while at the same time the nonlinearity parameters (Q, I/I, S, T, e/e, and v/v) increase significantly. Further, the tensile properties are significantly improved by closing the alginate network by Ca at intermediate concentrations.
本研究考察了丙烯酰胺和海藻酸钠双网络水凝胶在大变形下的流变性能。钙离子浓度影响非线性行为，所有凝胶样品均表现出应变硬化、剪切变稠和剪切密实。本文重点研究了海藻酸钠浓度（作为第二网络构建块）和 Ca 浓度（显示它们连接强度）的系统变化。根据海藻酸钠含量和 pH 值，前体溶液呈现出典型的粘弹性溶液行为。凝胶是高弹性固体，只有相对较小的粘弹性成分，即它们的蠕变和蠕变回复行为在很短的时间内就表明其处于固态，而线性粘弹相角非常小。当通过添加 Ca 关闭第二网络（海藻酸钠）时，非线性区域的起始点显著降低，同时非线性参数（Q、I/I、S、T、e/e 和 v/v）显著增加。此外，通过在中间浓度下用 Ca 关闭海藻酸钠网络，拉伸性能得到显著改善。
