Structure, dynamics, and rheology of colloid-polymer mixtures: From liquids to gels
Structure, dynamics, and rheology of colloid-polymer mixtures: From liquids to gels
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DOI：
10.1063/1.3103889
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发表时间：
2009-04-07
影响因子：
4.4
通讯作者：
Egelhaaf, S. U.
中科院分区：
文献类型：
--
作者：
Laurati, M.;Petekidis, G.;Egelhaaf, S. U.
我们调查的结构，动力学和粘弹性的胶体-聚合物混合物在中间胶体体积分数和不同的聚合物浓度，从而调整有吸引力的相互作用。在聚合物浓度的检查范围内，样品从流体到凝胶变化。在液相中，一个不断增加的相关长度的密度波动接近凝胶化边界时，观察到静态光散射和显微镜，表明集群和形成的空间跨越网络。同时，由动态光散射确定的相关函数完全衰减，表明没有动力学逮捕。聚类和形成的瞬态网络时，接近凝胶化边界的样品的粘弹性的显着变化的支持。当聚合物浓度超过凝胶化边界时，流变性质再次发生定性变化，现在它们与胶体凝胶的形成一致。我们的实验结果，即凝胶化边界的位置以及弹性（存储）和粘性（损耗）模量，比较不同的理论模型。这些措施包括考虑逃逸时间以及预测的粘弹性模量的基础上的标度关系和模式耦合理论。
We investigate the structural, dynamical, and viscoelastic properties of colloid-polymer mixtures at intermediate colloid volume fraction and varying polymer concentrations, thereby tuning the attractive interactions. Within the examined range of polymer concentrations, the samples varied from fluids to gels. In the liquid phase, an increasing correlation length of the density fluctuations when approaching the gelation boundary was observed by static light scattering and microscopy, indicating clustering and formation of space-spanning networks. Simultaneously, the correlation function determined by dynamic light scattering decays completely, indicating the absence of dynamical arrest. Clustering and formation of transient networks when approaching the gelation boundary is supported by significant changes in the viscoelastic properties of the samples. Upon increasing the polymer concentration beyond the gelation boundary, the rheological properties changed qualitatively again, now they are consistent with the formation of colloidal gels. Our experimental results, namely, the location of the gelation boundary as well as the elastic (storage) and viscous (loss) moduli, are compared to different theoretical models. These include consideration of the escape time as well as predictions for the viscoelastic moduli based on scaling relations and mode coupling theories.