Elastocapillary interactions of thermoresponsive microgels across the volume phase transition temperatures
Elastocapillary interactions of thermoresponsive microgels across the volume phase transition temperatures
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DOI：
10.1016/j.jcis.2020.09.085
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发表时间：
2021-02-15
影响因子：
9.9
通讯作者：
Yong, Xin
中科院分区：
文献类型：
--
作者：
Chen, Shensheng;Yong, Xin
假设：已知热响应微凝胶的有效相互作用受其体积相变的影响。这些软胶体在膨胀状态下表现为排斥球，但在坍塌状态下表现出强烈的吸引力。我们假设这种微凝胶相互作用的转变是由表面张力和体弹性之间的相互作用所控制的。实验：利用耗散粒子动力学，我们模拟了两个粗粒度微凝胶颗粒之间的相互作用，它们具有较低的临界溶液温度，约为32℃，悬浮在显式溶剂中。从分子动力学模拟轨迹出发，系统表征了不同交联密度微凝胶在12 ~ 58℃范围内的平均力势。发现：揭示了微凝胶在不同状态下相互作用的详细动力学。模拟结果表明，在高温下，微凝胶之间会形成毛细管桥，从而在接触时产生强大的吸引力。提出了一种基于界面热力学的弹性毛细管模型来描述微凝胶相互作用，并能准确预测大范围温度和重叠距离下的模拟数据。该结果为软胶体之间的有效相互作用提供了重要的物理见解，为刺激响应微凝胶的广泛应用奠定了基础。(C) 2020爱思唯尔公司版权所有。
Hypothesis: Effective interactions of thermoresponsive microgels are known to be influenced by their volume phase transition. These soft colloids behave as repulsive spheres in the swollen state but show strong attraction in the collapsed state. We hypothesize that this transition in microgel interactions is governed by the interplay between surface tension and bulk elasticity.Experiments: Using dissipative particle dynamics, we modeled the interactions between two coarse-grained microgel particles having a lower critical solution temperature around 32 degrees C, which are suspended in an explicit solvent. The potentials of mean force between microgels with different crosslinking densities were systematically characterized in the temperature range of 12-58 degrees C across the volume phase transition from steered molecular dynamics simulation trajectories.Findings: The detailed dynamics of interaction is uncovered for microgels in different states. The simulations reveal the formation of capillary bridges between collapsed microgels at high temperatures, which contributes to strong attraction at contact. An elastocapillary model based on interface thermodynamics is proposed to describe microgel interactions and accurately predicts simulation data in a wide range of temperatures and overlapping distances. The results provide important physical insights into effective interactions between soft colloids that underpin broad applications of stimuli-responsive microgels. (C) 2020 Elsevier Inc. All rights reserved.