Dynamic Wetting of Adaptive and Responsive Polyelectrolyte Substrates: A multiscale approach

自适应和响应性聚电解质基底的动态润湿：多尺度方法

• 批准号: 505842923
• 负责人: Professorin Dr. Regine von Klitzing
• 金额: --
• 依托单位: Arbeitsgruppe Weiche Materie an Grenzflächen
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/505842923?language=en
• 关键词: Dynamic; Wetting; Adaptive; Responsive; Polyelectrolyte

Wetting of polymer substrates by aqueous solutions is of specific interest in the context of the adhesion of biologically relevant systems like cells or proteins, but also for the technical control of wetting. Polymer substrates which contain charges or polar groups have a strong tendency to swell in water. Therefore, not only elastic but also adaptive properties of the substrate affect the wetting properties. The global aim of the present project is the understanding of the relation between the adaptation/response of polyelectrolyte substrates and their dynamic wetting properties. In the present project adaptation refers to swelling of the polyelectrolyte substrate caused by the (partial) uptake of the wetting liquid which is water or an aqueous salt solution. One class of studied adaptive substrate is responsive to temperature, which raises the question how a change in temperature affects wetting properties.In this context the project aims to contribute to a better understanding of wetting phenomena on nanoscopic/mesoscopic length scale (10 nm - 1 m) lateral and vertical to the surface close to the three-phase contact line (TPCL). Therefore, AFM techniques will be used. To make a link to wetting phenomena on a macroscopic length scale, typical static and dynamic wetting experiments (i.e. sessile drop, drop on a tilted plate, advancing and receding contact angle measurements) will be also carried out. Surface effects like surface elasticity, surface charge and interfacial molecular rearrangement are assumed to govern hysteresis effects on a nano/mesoscale which affects macroscopic wetting phenomena. Three types of surface deformation might occur on the nanoscale and might contribute to the overall profile of the TPCL: 1) A precursor film in front of the droplet, which is dominated by the disjoining pressure, 2) a rim of swollen substrate which is due to transport of liquid from the droplet into the substrate lateral (and vertical) to the substrate surface and 3) a wetting ridge induced by vertical components of the surface stress.The project aims to disentangle the different surface effects on wetting phenomena.As polyelectrolyte substrates polyelectrolyte multilayers (PEMs) and layers/multilayers of adsorbed PNIAPM microgel are used. Both can be considered as gels. Both types of substrates are complementary with respect to their advantages and allows control of surface charge (sign, density), range of achievable thickness, mechanical and rheological properties, hydrophilic/hydrophilic balance and their response to temperature. Cooperations are planned within the SPP with experimentalists and theoreticians in order to get deeper insight into the link between wetting phenomena on different length scales.

在细胞或蛋白质等生物相关系统的粘附背景下，水溶液对聚合物底物的润湿是一个特别感兴趣的问题，同时也是润湿的技术控制。含有电荷或极性基团的聚合物底物在水中有很强的膨胀倾向。因此，衬底的弹性和自适应性能不仅会影响其润湿性能。本项目的总体目标是了解聚电解质基质的适应/响应与其动态润湿特性之间的关系。在本项目中，适应是指由于（部分）吸收湿性液体（水或含水盐溶液）而引起的多电解质底物的膨胀。一类研究的自适应衬底对温度有响应，这就提出了温度变化如何影响润湿特性的问题。在这种情况下，该项目旨在有助于更好地理解纳米/介观长度尺度（10 nm - 1m）上的润湿现象，横向和垂直于接近三相接触线（TPCL）的表面。因此，AFM技术将被使用。为了与宏观长度尺度上的润湿现象联系起来，我们还将进行典型的静态和动态润湿实验（即无柄滴、倾斜板上滴、推进和后退接触角测量）。表面弹性、表面电荷和界面分子重排等表面效应被认为控制着纳米/中尺度的滞后效应，从而影响宏观润湿现象。三种类型的表面变形可能在纳米尺度上发生，并可能对TPCL的整体轮廓有贡献：1)液滴前面的前驱体膜，这是由分离压力主导的；2)由于液体从液滴向衬底的横向（和垂直）运输而导致的衬底肿胀边缘；3)由表面应力的垂直分量引起的润湿脊。该项目旨在解开不同表面对润湿现象的影响。聚电解质的衬底采用聚电解质多层膜（PEMs）和层/多层吸附的PNIAPM微凝胶。两者都可以被认为是凝胶。这两种类型的衬底在优点上是互补的，并且可以控制表面电荷（符号，密度），可实现的厚度范围，机械和流变特性，亲水/亲水平衡及其对温度的响应。SPP计划与实验学家和理论家进行合作，以便更深入地了解不同长度尺度上的润湿现象之间的联系。