Functional microporous materials

今天，微孔泡沫在几个应用中被发现，因为它们的低密度导致良好的特定机械性能（每单位重量的强度）。然而，总体泡沫性能主要由其结构控制，不仅在泡孔尺寸和泡孔密度方面，而且在泡孔形态（变形和取向）方面。因此，本研究的长期目标是了解如何使用加工条件来控制微孔聚合物的最终形态。在未来五年内，重点将放在两个重要的应用：气体分离和压电膜。 该项目的第一部分将集中在应用聚合物膜（平膜或中空纤维）已开发的气体净化。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性，以及通过添加多孔纳米颗粒如沸石、金属有机骨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），以在所有相之间获得良好的分散性和相容性（粘合性）。为了解决这个问题，提出了通过使用双螺杆挤出机作为化学反应器（反应挤出）来原位生产纳米颗粒和发泡剂。 第二部分的工作将致力于生产压电聚合物膜。这些材料现在用于汽车和医疗应用的传感器和传感器，以及体育用品和运输/包装物流，用于实时冲击损伤监测。压电性与材料在机械应力下发生形变的可能性有关。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，不仅泡孔尺寸和泡孔密度很重要，而且泡孔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=单轴拉伸，或挤出吹塑=双轴拉伸）以生产单层或多层。 一旦优化，该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，功能包装，材料处理，运输，隔音材料，能源（电池/燃料电池），电池隔板，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4名学生和1名技术人员。

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.