Construction of ordered porous polymer film and functionality of pore structure via microemulsion template method

Abstract

Surface ordered porous polymer films have shown the great application prospect in the fields of optoelectronic devices, separation, bioscience, filtration and medicine. Among the various kinds of self-assembled methods, water droplet template approach has been widely investigated owing to its easy operation, wide application and low cost features. In this paper, we present and review the preparation of ordered porous polymer films via microemulsion method and the functionalization of cavity structures. We firstly introduce the development of microemulsion approach, the detail preparation procedures, morphology and dimension of ordered porous surfaces which usually exhibit hexagonal close packed honeycomb structures at several micrometers. Then we discuss the influence factors of preparation for ordered cavity structures, such as the surfactant, solvent, water content, droplet dimension and so on, and after that we provide the formation mechanism of porous films through microemulsion method utilizing the dynamic integration, thermal capillary force and interface energy balance concepts. Further, we discuss the modification method of cavity inner surface which realizes the local assembly of diverse functional water-soluble components into the cavities by just adding these compounds into water phase of emulsion solution, and several kinds of water soluble components have been adopted, such as polyoxometalates and proteins. We also list some characterization methods for cavity decoration, for example, EDX analysis which can be used to test the location of large mass or high content elements, and CLSM images which can be adopted to detect the positon of fluorescent molecules. Then, we review the current applications of cavity structures, for example, using the components within the cavities to complete specific recognition of proteins and construction of protein microarray, constructing glucose-responsive insulin delivery system by adopting the modified cavities as the drug reservoir, and fabricating cell pattern through employing the cavities to in situ fix the cells whose reactivity can be maintained after the assembling process. Different with the bottom-up breath figure method, the advantages of the emulsion approach are that diverse functional water-soluble components can be assembled into the cavities in one step and the introduced stabilizer can also be used to modify the pore surface, indicating synchronous self-assemble decoration of pore surface and introduction of new components. It is envisioned that polymer porous membranes could be used in the fields of biological materials and detection, drug delivery devices and cell modification and assembly, and so forth.