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

本项目旨在发展聚合物薄膜在固体衬底上吸附的理论模型，并试图借助蒙特卡罗模拟和伴随的分析方法(特别是大分子的自洽场理论)来表征这些薄膜的润湿特性。聚合物链由具有可变链刚度(通过键角势能)的粗粒弹珠弹簧模型来模拟。将链长、温度和体积密度、薄膜厚度和衬底电势强度作为可变参数。同时考虑了底物单体的短程和长程相互作用，以及它们的组合。确定单个表面张力的基板聚合物GSP、基板-真空GSV和聚合物-真空GPV应定位润湿转变，并应研究接触角如何依赖于系统参数。特别关注聚合物膜的热力学状态和界面上的聚合物构型之间的相关性(线圈的取向和/或变形、链端的富集化、局部密度的变化等)。在第二步中，计划推广到双组分体系(对称的二元聚合物混合物AB)，以阐明相分离发生在垂直于衬底的方向或水平方向的条件。在后一种情况下，我们特别感兴趣的是界面聚合物A-聚合物B与聚合物膜和真空之间的界面之间的相互作用。在第一种情况下，我们对侧向分离引起的聚合物膜的粗化特别感兴趣。对于这两个问题，我们计划与基本理论(因为它可用于伊辛模型和简单流体)和相应的实验相联系。最后，我们将考虑将我们的研究推广到横向结构的衬底。

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.