Coatings with "Inverse Switching" Behaviour: New Applications of Core-Shell Hydrogel Particles

涂层可以为表面提供复杂的功能，显著改变底层材料的性能。特别是，新一代智能材料的设计需要新的概念，例如组织工程和细胞生长，创造智能呼吸活跃和防水纺织品，自我调节阀门和微流体设备。我们已经开发出一种智能表面的通用方法，这种表面在极性中变得亲水，在非极性溶剂中变得疏水。然而，对于许多实际应用来说，对外部刺激的相反的、更少的自然反应是可取的。该项目的重点是反向开关系统的设计，该系统在干燥状态下是亲水的，但在水中变得疏水。为了实现这一点，将用核壳水凝胶微粒(HMPs)对亲水性基质进行改性，HMPs包含一个可吸水膨胀的核和一个可透水的疏水壳。在干燥状态下，表面的一小部分将被水凝胶颗粒占据，而复合表面的性质将在很大程度上取决于亲水性基材的性质。在水中(或在水蒸气中)，HMPs膨胀并覆盖整个表面。在这种状态下，表面特性将由壳体的疏水特性的特性来定义。这一新概念将通过基于具有特殊结构和功能的水凝胶的聚合物化学和物理概念的结合来实现，因此需要在IPF以理想的方式提供的合成和专用表征技术方面的专业知识。

Coatings can provide complex functionalities to surfaces, changing the properties of the underlying material significantly. In particular the design of a new generation of smart materials requires new concepts, e.g. for tissue engineering and cell growth, for creation of intelligent breath-active and water-repelling textiles, for self-regulating valves and micro-fluidic devices. We have already developed a general approach to smart surfaces that become hydrophilic in polar and hydrophobic in apolar solvents. However, for many practical applications the inverse, much less natural response on external stimuli would be desired. The project focuses on the design of the inversely switching system, which is hydrophilic in the dry state, but becomes hydrophobic in water. To realize this, the hydrophilic substrate will be modified with core-shell hydrogel micro-particles (HMPs) containing a water-swellable core and a hydrophobic shell permeable for water. In dry state, the minor part of the surface will be occupied by the hydrogel particles, and properties of the composite surface will be highly defined by the properties of the hydrophilic substrate. In water (or in water vapor) the HMPs swell and cover the whole surface. In this state the surface properties will be defined by the properties of the hydrophobic character of the shell. This new concept will be realized by the combination of polymer chemical and physical concepts based on hydrogels with particular structure and functionality, and thus requires expertise both in synthetic and dedicated characterization techniques present at IPF in an ideal way.