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特性。特别是新一代智能材料的设计需要新的概念，例如用于组织工程和细胞生长，用于创造智能呼吸活性和拒水纺织品，用于自调节阀和微流体装置。我们已经开发了一种通用的方法来实现在极性溶剂中亲水和在极性溶剂中疏水的智能表面。然而，对于许多实际应用，相反，对外部刺激的自然反应要少得多。该项目重点设计了逆开关系统，该系统在干燥状态下为亲水性，但在水中变为疏水性。为了实现这一点，亲水底物将被核-壳水凝胶微颗粒（HMPs）修饰，其中包含一个可水膨胀的核和一个可渗透水的疏水壳。在干燥状态下，表面的一小部分将被水凝胶颗粒占据，复合表面的性能将高度取决于亲水基材的性能。在水中（或水蒸气中），HMPs膨胀并覆盖整个表面。在这种状态下，表面性质由壳层的疏水性质决定。这一新概念将通过基于具有特定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.