Slip of gels in colloid-polymer mixtures under shear
Slip of gels in colloid-polymer mixtures under shear
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DOI：
10.1039/c3sm27626k
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发表时间：
2013-01-01
期刊：
影响因子：
3.4
通讯作者：
Petekidis, George
中科院分区：
文献类型：
--
作者：
Ballesta, Pierre;Koumakis, Nick;Petekidis, George
我们研究了聚合物诱导的耗尽吸引下形成的胶体凝胶的时间依赖性流变学和滑移行为。在低施加的剪切速率的流动曲线的形状是暗示的滑动，我们确认使用共聚焦成像。依赖于时间的线性粘弹性测量显示出一个意想不到的下降的弹性模量低于粘性一个临界时间后。我们提出了一个动态相图表征的依赖于聚合物浓度和胶体体积分数的滑移。共聚焦成像链接滑移到随时间的簇的重构，这导致胶体网络和流变仪表面之间的接触的数量减少。这种行为是剪切速率依赖性的，并与凝胶结构的变化相关，凝胶结构从高剪切速率下的独立小聚集体变化为低剪切速率下的聚集体。
We investigate the time-dependent rheology and slip behaviour of colloidal gels formed under polymer-induced depletion attraction. The shape of the flow curves at low applied shear rates is suggestive of slip, which we confirm using confocal imaging. Time-dependent linear viscoelastic measurements show an unexpected drop of the elastic modulus below the viscous one after a critical time. We present a dynamic phase diagram characterizing the dependence of slip on polymer concentration and colloid volume fraction. Confocal imaging links slip to the restructuring of clusters with time, which leads to a reduction of the number of contacts between the colloidal network and the rheometer surfaces. Such behaviour is shear rate dependent and correlated to changes in the gel structure, which changed from independent small aggregates at high shear rates to percolated clusters at low shear rates.