Non-equilibrium flow at gradient surfaces: Fluid kinetics of droplets and particle motion

纳米级几何形状的流动在许多领域都很重要，例如在芯片生产、印刷技术和生物医学传感设备中。实验研究的重点是纳米尺度几何结构中的非平衡流动，这些流动是通过地形或化学表面结构产生的。流体将受到纳米通道的限制(通过共聚物的纳米级相分离产生)、不同的表面功能(可能具有类似的空间结构)或表面梯度(由混合聚合物刷子获得)的影响。流动将用含有聚合物和不同液体的溶液来研究，从而为研究非平衡流动提供了一个可调的模型系统。通过聚合物浓度的变化来调整粘度，并通过溶液的源或漏的存在来控制非平衡流动。流道衬底将流动的溶液限制在流道的受限空间内，并通过显微镜和散射技术研究作为流道宽度、流道粗糙度或流道形态等控制参数的函数的流动。可以通过化学反应对表面进行修饰，以提供特定的功能。例如，可以实现疏水或亲水行为，从而改变底物和溶液成分之间的相互作用。化学结构或梯度衬底提供了这种相互作用的空间变化，对于纳米流体而言，这可能显示出与沟道衬底类似的效果。因此，将比较地形和化学结构功能化模型表面对聚合物溶液和混合液体的纳米流体的影响，以提供更好的理解和可能的纳米水平的流动控制。

Flow in nanoscale geometries is of importance in many areas as for example in chip production, printing techniques and bio-medical sensing devices. The experimental investigation focuses on non-equilibrium flow in nanoscale geometries to be generated by topographic or chemical surface structuring. The fluidics will be influenced by confinement given by nano-channels, which are produced via nano-scale phase separation of copolymers, by different surface functionalities, which may be similarly spatially structured, or by surface gradients, which are obtained with mixed polymer brushes. Flow will be investigated with solutions containing polymers and different liquids thus providing a tunable model system for the investigation of non-equilibrium flow. By variation of polymer concentration the viscosity is adjusted, and by the presence of a source or drain for the solution the non-equilibrium flow is controlled. Channeled substrates provide a confinement of the flowing solution into the restricted space of the channels and flow is investigated by microscopic and scattering techniques as a function of control parameters such as channel width, channel roughness or channel morphology. The surface can be modified by chemical reaction to provide specific functionality. For instance hydrophobic or hydrophilic behavior can be achieved, thus changing interaction between substrate and components of the solution. Chemically structured or gradient substrates provide a spatial variation of this interaction which with respect to nanofluidics could show a similar effect as channeled substrates. Thus both topographic and chemically structured functionalized model surfaces will be compared with respect to their influence on nanofluidics of polymer solutions and mixed liquids to provide a better understanding and possibly control of flow at nanoscopic level.