Research Initiation Award: Formation of Porous Polymeric Materials Via Micro-Phase Separation in a Supercritical Solution

这项研究将集中在具有均匀亚微米细胞尺寸的多孔聚合物材料上，这些材料在膜、催化剂载体、人造皮肤等领域显示出巨大的应用前景。目前用于制备这些材料的液体相分离技术受到溶剂去除困难和温度梯度引入的结构不均一性的限制。提出了通过在超临界流体膨胀的聚合物网络中诱导微相分离来产生均匀的、多孔的聚合物材料。通过利用溶剂功率对压力的强烈依赖性，这是超临界流体的一个独特特性，人们可以对多孔材料中的微观结构进行比目前使用传统液体溶剂更精细的控制。研究计划将分为两个阶段。首先，我们将使用石英弹簧微天平和介电谱仪分别测量聚合物网络在超临界CO2中的平衡溶胀组成和松弛行为。这将是第一次在网络/超临界流体系统上进行这样的测量。在第二阶段，微孔材料将通过超临界流体-溶胀网络中的相分离生成。孔隙度将使用常规技术测量，并与在初始程序阶段汇编的基本热力学信息相关联。

This research will focus upon porous polymeric materials exhibiting a uniform sub-micron cell size which show great promise in applications such as membranes, catalyst supports, artificial skin, etc. Current liquid-based phase separation technologies for producing these materials are limited be difficulties in solvent removal and structural heterogeneity introduced by thermal gradients. It is proposed to generate uniform, cellular polymeric materials via a micro-phase separation induced in a polymer network swollen by a supericrtical fluid. By taking advantage of the strong dependence of solvent power on pressure, a unique characteristic of supercritical fluids, one can assume finer control over the microstructure in porous materials than is presently available using conventional liquid solvents. The research program will be divided into two phases. In the first, the equilibrium swelling composition and the relaxation behavior of a polymer network exposed to supercritical CO2 will be measured using a quartz spring microbalance and dielectric spectrometer, respectively. These will be the first such measurements on a network/supercritical fluid system. In the second phase, microporous materials will be generated via a phase separation in a supercritical fluid- swollen network. Porosity will be measured using conventional techniques and correlated with the fundamental thermodynamic information compiled during the initial program phase.