Development of Hierarchical Micro/Nano Structured Multi-Responsive Surfaces for Microfluid Applications

刺激响应涂层的最新进展使其能够集成为纳米技术中的功能元件，如微流体，微机电系统（MEMS），其中由于表面体积比大，界面力强烈影响器件性能。然而，反应性涂料存在主要缺点：(i)缺乏反应速度，选择性和可逆性，（ii）环境稳定性差，（iii）对结构功能关系的理解有限，这些对于设计构建多功能表面的可靠规则至关重要。利用表面化学、聚合物科学和自组装的方法，该计划旨在通过开发和研究新一代响应性分层微/纳米结构涂层来克服这些限制，这些涂层的物理性能（结构和机械性能）和表面化学可以使用不同的外部刺激（光、温度、pH、离子强度）独立可逆地调整。***提出的微观结构由永久附着在衬底上的二维纳米凝胶阵列组成，其尺寸和弹性（通过膨胀/收缩行为）可以通过温度或光调节，从而允许表面形貌（粗糙度）和刚度可逆控制。纳米凝胶表面将被聚合物刷功能化，聚合物刷的纳米结构和化学成分可以通过不同的刺激（pH值、离子强度或温度）独立控制，这取决于所需的自适应精细表面特性。该微观结构有望增强外刷层的表面化学效果。该计划将涉及四个方面：(i)开发和优化用不同聚合物刷功能化的热响应二维纳米凝胶阵列；（ii）开发和优化具有显著膨胀效应的光响应纳米凝胶，并将其固定在二维阵列中；（iii）研究和优化在(i)和（ii）中开发的涂层对不同刺激的响应行为；（iv）探索作为微流体控制功能元件的潜在应用。***所提出的分层纳米/微观结构的各种调制方式很可能会带来革命性的进步和新技术的创造，特别是在生物医学表面工程和微流体领域，小型功能部件的先进组装越来越需要。*****

Recent advances in stimuli-responsive coatings enable their integration as functional elements in nanotechnologies such as microfluidics, Micro Electro-Mechanical Systems (MEMS) where interfacial forces strongly influence the device performance because of the large surface-to-volume ratio. However, responsive coatings are suffering from major shortcomings: (i) lack of responsiveness rapidity, selectivity and reversibility, (ii) poor environmental stability, (iii) limited understanding of the structurefunction relationship, which are all critical to design reliable rules for building multifunctional surfaces. Using approaches from surface chemistry, polymer sciences and self-assembly, the proposed program aims to overcome these limitations by developing and investigating a new generation of responsive hierarchical micro/nano-structured coatings whose physical properties (structure and mechanical properties) and surface chemistry can be tuned independently and reversibly using different external stimuli (light, temperature, pH, ionic strength). ***The proposed microstructure consists of 2D nanogel arrays permanently attached to substrates and whose size and elasticity (via swelling/shrinking behavior) can be modulated by temperature or light allowing surface topography (roughness) and stiffness to be reversibly controlled. The nanogel surface will be functionalized with polymer brushes whose nanostructure and chemistry can be independently controlled using different stimuli (pH, ionic strength or temperature) depending on the desired adaptive fine surface properties. The microstructure is expected to enhance the effect of surface chemistry of the outer brush layer. The program will involve four aspects: (i) development and optimization of thermo-responsive 2D nanogel arrays functionalized with different polymer brushes, (ii) development and optimization of photo-responsive nanogels exhibiting significant swelling effects and their immobilization into 2D arrays, (iii) investigation and optimization of the responsive behavior of the coatings developed in (i) and (ii) towards different stimuli and (iv) exploration of potential applications as functional elements for fluid control in microfluidics.***The various ways the proposed hierarchical nano/micro structures can be modulated will most likely enable revolutionary advances and creation of new technologies, particularly in biomedical surface engineering and microfluidics where advanced assembly of small functional components are increasingly required.*****