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arXiv 2407.01059cond-mat.soft
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软响应性胶体的非平衡弛豫

Nonequilibrium relaxation of soft responsive colloids

José López-Molina, Sebastien Groh, Joachim Dzubiella, Arturo Moncho-Jordá

AI总结:

本文提出响应性胶体的平均场动力学密度泛函理论,研究时变外场下平动与构象耦合的非平衡弛豫,发现外势开关过程中积分观测量呈时间不对称弛豫,并可由平动与构象扩散时间尺度比调控。

摘要:

刺激响应性大分子在其动力学过程中表现出大幅构象变化,有时会发生状态切换,是开发软功能材料不可或缺的性质。本文引入一种针对响应性胶体(RCs)模型的平均场动力学密度泛函理论(DDFT),用于研究胶体分散体系在时间依赖外场中的非平衡动力学,重点关注弛豫过程中平动与构象动力学的耦合。具体而言,我们考虑具有双峰尺寸分布的软高斯粒子,其处于两个约束壁之间,并受到时间依赖(开启和关闭)的外加重力场和渗透场作用。我们发现体系具有丰富的弛豫行为,与基于粒子的布朗动力学(BD)计算机模拟结果高度一致。特别是,对于外势的激活/去激活,我们分别发现积分观测量(壁压、平均尺寸、液体质心)的时间不对称弛豫,这些行为可通过平动与构象扩散时间尺度之比进行调控。因此,我们的工作为研究具有多自由度和层级弛豫的复杂软物质非平衡弛豫动力学铺平了道路。

英文摘要:

Stimuli-responsive macromolecules display large conformational changes during their dynamics, sometimes switching states, and are an integral property for the development of soft functional materials. Here, we introduce a mean-field dynamical density functional theory (DDFT) for a model of responsive colloids (RCs) to study the nonequilibrium dynamics of a colloidal dispersion in time-dependent external fields, with a focus on the coupling of translational and conformational dynamics during their relaxation. Specifically, we consider soft Gaussian particles with a bimodal size distribution between two confining walls with time-dependent (switching-on and off) external gravitational and osmotic fields. We find a rich relaxation behavior of the systems in excellent agreement with particle-based Brownian dynamics (BD) computer simulations. In particular, we find time-asymmetric relaxations of integrated observables (wall pressures, mean size, liquid center-of-mass) for activation/deactivation of external potentials, respectively, which are tuneable by the ratio of translational and conformational diffusion time scales. Our work paves thus the way for studying the nonequilibrium relaxation dynamics of complex soft matter with multiple degrees of freedom and hierarchical relaxations.

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