Small Grant for Exploratory Research: Molecular Engineering at Ultrathin Organic Films for Membrane Separations

膜在分离过程中的有效性取决于它的选择性和通透性或通量。不幸的是，选择性和渗透性通常是相互权衡的——控制选择性的相同机制，如孔径大小，调节物质通过膜的通量。该SGER建议制造复合膜，以最大限度地提高选择性和渗透性。多孔基材用作衬底材料，从而提供机械强度并确保高渗透性。然后通过在衬底上安装无孔超薄微结构薄膜来控制选择性。PI建议用Langmuir Blodgett技术或通过溶液吸附自组装形成的有凝聚力的、分子有序的有机单层或多层薄膜来制作这些微结构薄膜。这些薄膜对感兴趣的气体的渗透率将通过使用石英晶体微天平或表面声波装置来测量。在这种类型的测量中，薄膜附着在（典型的）石英压电晶体上，并对晶体施加振荡电场。这种应用使声波以特定的共振频率传播。薄膜质量的微小变化可以通过晶体谐振频率的变化来检测。薄膜将暴露在气体环境中，为了测量渗透率，将及时测量频移。研究将重点放在薄膜的微观结构和物理化学性质与渗透率的关系上。具体来说，不同流动性、表面特性、化学性质和缺陷结构的薄膜将被检查。

The effectiveness of a membrane in a separation process is based on the degree of its selectivity and its permeability or throughput. Unfortunately, selectivity and permeability are generally traded off - the same mechanisms which control selectivity, such as pore size, regulate the flux of material through the membrane. This SGER proposal suggests fabricating composite membranes in order to maximize both selectivity and permeability. A porous substrate is used as the backing material thus providing mechanical strength and insuring high permeability. Selectivity is then controlled by mounting a nonporous ultrathin microstructured film over the backing sheet. The PI suggests making these microstructured films out of cohesive, molecularly ordered, organic mono- or multi-layered films formed either by the Langmuir Blodgett technique or self assembly via adsorption from solution. The permeability of these films to gases of interest will be measured by using either a quartz crystal microbalance or a surface acoustic wave device. In this type of measurement this film is attached to a (typically) quartz piezoelectric crystal, and an oscillating electric field is applied to the crystal. This application causes an acoustic wave to propagate with a particular resonant frequency. Minute changes in mass of the film can be detected by shifts in the resonant frequency of the crystal. The film will be exposed to a gaseous environment, and frequency shifts will be measured in time in order to measure the permeability. The study will focus on how the microstructure architecture and physicochemical properties of the films relate to the permeability. Specifically films of different fluidity, surface characteristic, chemistries and defect structure will be examines.