Microstructure, microrheology, and dynamics of laponite® and laponite®-poly(ethylene oxide) glasses and dispersions
Microstructure, microrheology, and dynamics of laponite® and laponite®-poly(ethylene oxide) glasses and dispersions
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DOI：
10.1007/s00397-020-01210-y
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发表时间：
2020-04
期刊：
影响因子：
2.3
通讯作者：
Bingqian Zheng;James R Breton;R. S. Patel;S. Bhatia
中科院分区：
文献类型：
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作者：
Bingqian Zheng;James R Breton;R. S. Patel;S. Bhatia
我们利用基于动态光散射 (DLS) 的被动微流变学来探索微尺度 Laponite® 和 Laponite® 聚合物玻璃和分散体的动力学和结构演化。结果表明，随着 Laponite® 浓度和老化时间的增加，Laponite® 分散体的动态不均匀性增加。在纯 Laponite® 分散体中，由于形成排斥玻璃，在 Laponite® 浓度较高时，硬度会增强，并且动力学会延迟。在中等分子量 20 kg/mol 的 PEO 存在下，2 wt% Laponite® 分散体的微粘弹性特性在老化时表现出与 PEO 浓度的非单调效应，这与之前从本体流变学获得的结果一致。然而，通过 DLS 微流变学获得的超出凝胶点的分散体的粘弹性模量 (G' 和 G”) 的大小低于通过传统流变学获得的值。我们的结果表明，DLS 微流变学可用于定性研究凝胶和软固体的动态转变以及微粘弹性特性。图形摘要
We utilize dynamic light scattering (DLS)-based passive microrheology to probe the dynamics and structural evolution of laponite® and laponite®-polymer glasses and dispersions at the microscale. The results reveal an increase in the dynamic heterogeneity of laponite® dispersions with an increase of laponite® concentration and aging time. In neat laponite® dispersions, the degree of stiffness is enhanced and the dynamics are retarded at higher laponite® concentration due to the formation of a repulsive glass. In the presence of PEO with a moderate molecular weight of 20 kg/mol, the microviscoelastic properties of 2 wt% laponite® dispersions show non-monotonic effects with PEO concentration upon aging, which agrees with the results obtained previously from bulk rheology. However, the magnitudes of the viscoelastic moduli (G’andG”) of dispersions beyond the gel point obtained from DLS-microrheology is lower than that obtained from conventional rheology. Our results suggest that the DLS-microrheology can be used to qualitatively study dynamic transitions and the microviscoelastic properties of gels and soft solids.Graphical abstract