Feedback-controlled molecular transport through responsive polymer membranes

分子溶质通过致密聚合物膜的运输对于气体分离、海水淡化和纳滤（“分子筛分”）、透析治疗或选择性药物输送等应用至关重要。在标准的理论方法中，输运是在线性响应水平上建模的，即假定通量与驱动场或化学梯度简单成正比，并根据膜的平衡溶剂化和波动行为估计膜的渗透率。然而，使用的现代材料，例如热敏聚合物，显示出复杂的非线性响应和反馈行为，线性输运理论预计将被打破。作为“降低非平衡系统的复杂性”研究单元的一部分，该项目的目标是了解通过响应性聚合物膜驱动的溶质的非平衡和反馈影响的运输，从而将渗透率的重要概念扩展到高度非线性，非平衡的情况。这一部分将直接通过隐式溶剂但“微观”的方法进行研究，即聚合物网络中单体解析的朗格万输运模拟，并将通过各种（降低）粗粒化程度的适当非平衡理论的发展加以补充。这种复杂性的降低，例如福克-普朗克框架和随机朗之万框架，将导致对非平衡情况下膜渗透性和通量力响应的新的和适当的定义，从而有助于形成新的材料。

The transport of molecular solutes through dense polymeric membranes is of key importance for applications like gas separation, desalination and nanofiltration (”molecular sieving”), or medical treatments by dialysis or selective drug delivery. In standard theoretical approaches the transport is modeled on a linear response level, i.e., fluxes are assumed to be simply proportional to the driving fields or chemical gradients and the membrane permeability is estimated from equilibrium solvation and fluctuation behavior of the membrane. However, modern materials used, e.g., thermosensitive polymers, display a complex nonlinear response and feedback behavior, and linear transport theory is expected to break down. part of the Research Unit "Reducing complexity of nonequilibrium Systems", the goal of this project is to understand non-equilibrium and feedback-influenced transport of solutes driven through responsive polymer membranes and will thus extend the important concept of permeability to highly non-linear, non-equilibrium situations. This will be studied in one part directly by implicit-solvent but "microscopic", i.e., monomer-resolved Langevin simulations of transport in polymer networks, and will be complemented by the development of the appropriate non-equilibrium theories with various (reduced) degrees of coarse-graining. Such a reduction of complexity in, e.g., Fokker-Planck and stochastic Langevin frameworks will lead to new and proper definitions for membrane permeability and flux-force responses in non-equilibrium situations, and will thus help shaping new materials.