Theoretische und experimentelle Untersuchungen von Benetzungseigenschaften von dünnen ein- und zweikomponentigen Polymerfilmen

本项目旨在建立吸附在固体基质上的聚合物薄膜的理论模型，并打算借助蒙特卡罗模拟和伴随的分析方法（特别是大分子的自一致场理论）来表征这些薄膜的润湿特性。聚合物链的建模采用粗粒度串珠弹簧模型，具有可变链刚度（通过键角电位）。链长、温度和堆积密度、薄膜厚度和衬底电位强度被视为可变参数。考虑了短程和长距离底物单体相互作用及其组合。确定基体-聚合物gSP、基体-真空gSV和聚合物-真空gPV的单独表面张力，必须确定润湿过渡的位置，并研究接触角如何依赖于系统参数。特别感兴趣的是聚合物薄膜的热力学状态与界面上的聚合物构型（线圈的取向和/或变形，链端富集，局部密度的变化等）和相应的熵贡献之间的关系。在第二步中，计划推广到双组分体系（对称二元聚合物混合物AB），以阐明相分离在垂直于衬底或水平方向上发生的条件。在后一种情况下，我们对界面聚合物A -聚合物B与聚合物膜和真空之间的界面的相互作用特别感兴趣。在第一种情况下，我们特别感兴趣的是由侧向分离引起的聚合物薄膜的粗化。对于这两个问题，我们计划将基础理论（因为它适用于伊辛模型和简单流体）和相应的实验联系起来。最后，将我们的研究推广到横向结构的底物。

This project aims at the development of theoretical models for thin polymeric films adsorbed on solid substrate, and intends to characterize the wetting properties of these films with the help of Monte Carlo simulations and accompanying analytical methods (in particular the self-consistent field theory of macromolecules). Polymer chains are modeled by coarse-grained beadspring models with variable chain stiffness (via a bond angle potential). Chain length, temperatur and bulk density, film thickness, and the strength of the substrate potential are treated as variable parameters. Both short range and long range substrate monomer interactions are considered, as well as combinations therof. Determining the individual surface tensions substrate polymer gSP, substrate-vacuum gSV and polymer-vacuum gPV the wetting transitions shall be located and it shall be studied how the contact angle depends on the system parameters. Particular interest is devoted to the correlation between the thermodynamic states of the polymer film and the polymer configurations at the interfaces (orientation and/or deformation of the coils, enrichment of chain ends, changes of the local density, etc.) and corresponding entropic contributions.In a second step a generalization to two-component systems (symmetrical binary polymer mixtures AB) is planned to clarify the conditions under which phase separation occurs in perpendicular orientation to the substrate or horizontally. In the latter case we are particularly interested in the interaction of the interface polymer A - polymer B with the interface between the polymerfilm and the vacuum. In the first case we are particularly interested in the roughening of the polymer film caused by lateral unmixing.For both problems we plan to make connections both with fundamental theory (as it is available for Ising model and simple fluids) and with corresponding experiments. Finally the generalization of our studies to laterally structured substrates will be considered.