Inducing Stratification of Colloidal Mixtures with a Mixed Binary Solvent
Inducing Stratification of Colloidal Mixtures with a Mixed Binary Solvent
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用混合二元溶剂诱导胶体混合物分层
DOI：
10.1039/d3sm01192e
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发表时间：
2023
期刊：
影响因子：
3.4
通讯作者：
Cheng, Shengfeng
中科院分区：
文献类型：
--
作者：
Liu, Binghan;Grest, Gary S.;Cheng, Shengfeng
分子动力学模拟被用来证明，一个二元溶剂可以用来分层胶体混合物时，悬浮液被迅速干燥。溶剂由两种成分组成，一种比另一种更易挥发。当以高速率蒸发时，挥发性较大的组分在蒸发前沿附近耗尽，并从混合物的主体到液-气界面形成负浓度梯度，而挥发性较小的溶剂在同一区域富集，并呈现正浓度梯度。如果一种胶体颗粒优先被吸引到挥发性更强的溶剂，而另一种胶体颗粒优先被吸引到挥发性较弱的溶剂，则这种梯度可用于驱动胶体颗粒的二元混合物分层。在溶剂蒸发过程中，优先吸引到挥发性较低的溶剂的胶体颗粒的分数在蒸发前沿增强，而具有更强的吸引力的胶体颗粒与更挥发性的溶剂被驱离界面区域。结果，即使两种胶体具有相同的尺寸，胶体颗粒在干燥后也显示出分层分布。
Molecular dynamics simulations are used to demonstrate that a binary solvent can be used to stratify colloidal mixtures when the suspension is rapidly dried. The solvent consists of two components, one more volatile than the other. When evaporated at high rates, the more volatile component becomes depleted near the evaporation front and develops a negative concentration gradient from the bulk of the mixture to the liquid–vapor interface while the less volatile solvent is enriched in the same region and exhibit a positive concentration gradient. Such gradients can be used to drive a binary mixture of colloidal particles to stratify if one is preferentially attracted to the more volatile solvent and the other to the less volatile solvent. During solvent evaporation, the fraction of colloidal particles preferentially attracted to the less volatile solvent is enhanced at the evaporation front, whereas the colloidal particles having stronger attractions with the more volatile solvent are driven away from the interfacial region. As a result, the colloidal particles show a stratified distribution after drying, even if the two colloids have the same size.