It is known that microgels can serve as soft, permeable and stimuli-responsive alternative of solid colloidal particles to stabilize oil–water emulsions. The driving force for the adsorption of the microgels on interface of two immiscible liquids is a shielding of unfavorable oil–water contacts by adsorbed subchains, that is, the decrease of the surface tension between the liquids. Such phenomenon usually proceeds if volume fractions of the two liquids are comparable with each other and the microgel concentration is not high enough. The natural question arises: what is going on with the system in the opposite case of strongly asymmetric mixture (one of the liquids (oil) has a very small fraction) or high microgel concentration (the overall volume of the microgels exceeds the volume of the minor oil component)? Here we demonstrate that the microgels uptake the oil whose concentration within the microgels can be orders of magnitude higher than outside, leading to the additional microgel swelling (in comparison with the swelling in water). Thus, the microgels can serve as scavengers and concentrators of liquids dissolved in water. At first glance, this effect seems counterintuitive. However, it has a clear physical reason related to the incompatibility of oil and water. Absorption of the oil by microgels reduces unfavorable oil–water contacts by microgel segments: the microgels have a higher concentration of the segments at the periphery, forming a shell. The microgels with uptaken oil are stable toward aggregation at very small oil concentration in the mixture. However, an increase in the oil concentration can lead to aggregation of the microgels into dimers, trimers, and so on. The increasing concentration of oil mediates the attraction between the microgels: the oil in the aggregates appears to be localized in-between the microgels instead of their interior, which is accompanied by the release of the elastic stress of the microgels. A further increase in the oil concentration results in a growth of the size of the oil droplets between the microgels and the number of the microgels at the droplet’s periphery, that is, the emulsion is formed.

中文翻译：

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微凝胶在两种不混溶液体的混合物中清除其中一种液体与乳液稳定

众所周知，微凝胶可以作为固体胶体颗粒的柔软、可渗透和刺激响应的替代品，以稳定油水乳液。微凝胶吸附在两种不混溶液体界面的驱动力是通过吸附的子链屏蔽不利的油水接触，即降低液体之间的表面张力。如果两种液体的体积分数相当且微凝胶浓度不够高，这种现象通常会发生。很自然的问题出现了：在强不对称混合物（其中一种液体（油）的比例非常小）或微凝胶浓度高（微凝胶的总体积超过微量油成分的体积）的相反情况下，系统会发生什么？在这里，我们证明微凝胶吸收油，其在微凝胶内的浓度可以比外部高几个数量级，导致额外的微凝胶膨胀（与水中的膨胀相比）。因此，微凝胶可以用作溶解在水中的液体的清除剂和浓缩剂。乍一看，这种效果似乎违反直觉。但是，它有一个明确的物理原因，与油和水的不相容性有关。微凝胶对油的吸收减少了微凝胶段不利的油水接触：微凝胶在外围具有较高浓度的片段，形成壳。具有吸收油的微凝胶在混合物中的油浓度非常低时对聚集是稳定的。然而，油浓度的增加会导致微凝胶聚集成二聚体、三聚体等。油浓度的增加介导了微凝胶之间的吸引力：聚集体中的油似乎位于微凝胶之间而不是它们的内部，这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。具有吸收油的微凝胶在混合物中的油浓度非常低时对聚集是稳定的。然而，油浓度的增加会导致微凝胶聚集成二聚体、三聚体等。油浓度的增加介导了微凝胶之间的吸引力：聚集体中的油似乎位于微凝胶之间而不是它们的内部，这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。具有吸收油的微凝胶在混合物中的油浓度非常低时对聚集是稳定的。然而，油浓度的增加会导致微凝胶聚集成二聚体、三聚体等。油浓度的增加介导了微凝胶之间的吸引力：聚集体中的油似乎位于微凝胶之间而不是它们的内部，这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。油浓度的增加会导致微凝胶聚集成二聚体、三聚体等。油浓度的增加介导了微凝胶之间的吸引力：聚集体中的油似乎位于微凝胶之间而不是它们的内部，这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。油浓度的增加会导致微凝胶聚集成二聚体、三聚体等。油浓度的增加介导了微凝胶之间的吸引力：聚集体中的油似乎位于微凝胶之间而不是它们的内部，这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。这伴随着微凝胶弹性应力的释放。油浓度的进一步增加导致微凝胶之间的油滴尺寸和液滴外围的微凝胶数量增加，即形成乳液。