Hyper-cross-linked, hybrid membranes via interfacial polymerization

Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on the type, size and flexibility of the constituents. The collection of polymers that can be synthesized via interfacial polymerization includes polyamides, polyurethanes, polyureas, polyanilines, polyimides, and polycarbonates. In addition, the technique can be used to prepare defect-free, ultrathin films of metal organic frameworks, organic-inorganic hybrids, and bio-hybrids. Here, inorganic-organic network materials based on polyhedral oligomeric silsesquioxanes (POSS) that are covalently bound by imide bridges have been prepared. The membranes are characterized by a high degree of cross-linking, as a result of the large number of functional groups on the POSS cages. Even at temperatures up to 300 °C, macromolecular dynamics of the hybrid networks based on short imide bridges is limited. This is illustrated by the relatively small shrinkage during heat treatment of the poly[POSS-(amic acid)] precursors and the high permselectivities in gas separation applications at a broad temperature range. Poly(POSS imide)s with long, flexible imide bridges display a higher degree of network flexibility. The flexibility of the hybrid network materials prepared with relatively long imide bridges is reflected by the unique sorption behavior of fluoroalkane based poly(POSS-imide). The membrane layers sorb large amounts of CO2 and CH4, up to an extent that the molar volume of the adsorbed gas exceeds that of the liquid molar volume of these gases. The interfacial polymerization method used for the inorganic-organic networks has been extended towards biological hybrids. The preparation of all-protein layers that consist of enzymatically active and fluorescently active films is reported. The broad applicability of interfacial polymerization for the preparation of ultrathin hybrid films provide prospect for further development of materials with unique functionalities.