Functional microporous materials

如今，微孔泡沫由于其低密度而具有良好的机械性能（单位重量强度），在许多应用中得到了应用。然而，整体泡沫性能主要受其结构控制，不仅在细胞大小和细胞密度方面，而且在细胞形态（变形和取向）方面。因此，这项研究的长期目标是了解如何利用加工条件来控制微细胞聚合物的最终形态。在接下来的五年里，重点将放在两个重要的应用上：气体分离和压电膜。***该项目的第一部分将侧重于聚合物膜（扁平膜或中空纤维）用于气体净化的应用。混合基质膜的概念将用于通过优化聚合物泡沫基质来控制渗透率，以及通过添加多孔纳米颗粒（如沸石、金属有机框架和粘土）来控制选择性。除了材料选择之外，主要的挑战是优化加工条件（压力、温度、流速和设备几何形状），以获得所有相之间良好的分散和相容性（附着力）。为了解决这一问题，提出了利用双螺杆挤出机作为化学反应器（反应挤出）原位生产纳米颗粒和发泡剂的方法。***第二部分工作将致力于压电聚合物膜的生产。这些材料现在用于汽车和医疗应用的传感器和传感器，以及用于实时冲击损坏监测的体育用品和运输/包装物流。压电性与材料在机械应力作用下发生极化的可能性有关。为了在聚合物中获得这种效果，必须通过在材料表面产生正电荷和负电荷（充电）来扰乱电平衡。这就是泡沫结构发挥作用的地方，因为每单位体积可以产生非常高的界面面积。为了优化效果，不仅细胞尺寸和细胞密度很重要，而且细胞变形和壁厚也很重要。在这种情况下，将研究不同的方法（挤出压延=单轴延伸，或挤出吹制=双轴延伸）来生产单层或多层。***一旦优化，这项研究计划的结果将用于开发其他重要领域的技术，如汽车、建筑和建筑、功能性包装、材料处理、运输、隔音材料、能源（电池/燃料电池）、电池分离器、组织工程、水净化、气液吸收、过滤和反应工程（催化）。***每年将培训四名学生和一名技术员

Today, microcellular foams are found in several applications because of their low density leading to good specific mechanical properties (strength per unit weight). Nevertheless, the overall foam properties are mainly controlled by their structures, not only in terms of cell size and cell density, but also with respect to cell morphology (deformation and orientation). So the long term objective of this research is to understand how the processing conditions can be used to control the final morphology of microcellular polymers. In the next five years, the focus will be on two important applications: gas separation and piezoelectric membranes.***The first part of the project will focus on applications where polymer membranes (flat membranes or hollow fibers) have been developed for gas purification. The concept of mixed matrix membranes will be used as to control both permeability via an optimization of the polymer foam matrix, and selectivity via the addition of porous nano-particles like zeolites, metal organic frameworks, and clays. The main challenges, besides materials selection, is to optimize the processing conditions (pressure, temperature, flow rates, and equipment geometry) to get good dispersion and compatibility (adhesion) between all the phases. To solve this problem, it is proposed to produce in situ the nano-particles and blowing agents by using a twin-screw extruder as a chemical reactor (reactive extrusion).***The second part of the work will be devoted to the production of piezoelectric polymer membranes. These materials are now used in applications like transducers and sensors for automotive and medical applications, as well as sporting goods and transportation/packaging logistics for real-time impact damage monitoring. Piezoelectricity is related to the possibility of a material to polarize under mechanical stresses. To get the effect in a polymer, the electrical equilibrium must be perturbed by creating positive and negative charges at the surface of the material (charging). This is where the foam structure comes into play since a very high amount of interfacial area can be created per unit volume. To optimize the effect, not only cell size and cell density are important, but also cell deformation and wall thickness. In this case, different methods (extrusion calandering = uniaxial elongation, or extrusion blowing = biaxial elongation) will be studied to produce single layers or multi-layers.***Once optimized, the results of this research programme will be used to develop technologies for other important areas like automotive, building and construction, functional packaging, material handling, transportation, sound insulators, energy sources (battery/fuel cell), battery separators, tissue engineering, water purification, gas-liquid absorption, filtration, and reaction engineering (catalysis).***A total of four students and one technician per year will be trained.**