Based On Static Breath Figure Of Orderly Honeycomb Porous Thin Film Prepared By The Research

Recently, ordered honeycomb-patterned films have received considerable attention due to their potential applications in chemical sensors, pohotonic band gap, tissue-engineering, cell culture substrates, catalysis, microreactor, and separating membrane.Among those techniques for the fabrication of honeycomb-patterned porous films, the breath figure is one of the attractive self-assembling strategies for creating ordered porous structure due to its cheapness, facility, speedness, and the automatic remove of the condensed water droplets. The breath figure process is nonequilibrium and nonisothermal, which has many variables, including the polymer structure and property, choice of organic solvent, solution concentration, atmosphere temperature and humidity. The breath figure involves two kinds of processes. One is dynamic pocess, the other one is static process. Compared with dynamic process, any uncertainties caused by flow disturbing are minimized in the static process. Therefore, it is a simple and common process.Block copolymers, star polymers and polymers with polar end groups are believed to be good candidates to prepare porous films by breath figure method. The amphiphilic copolymer, which is an interfacial-active compound, is an optimal material for fabrication of honeycomb-patterned porous films. It tends to aggregate at the organic-water interface and to stabilize the water droplets.In this study, polystyrene-block-poly (acrylic acid)(PS-b-PAA) with well-defined structure was synthesized by atom transfer radical polymerization (ATRP). The amphiphilic block copolymer was used as a precursor for the fabrication of honeycomb-patterned porous film by the static breath-figure method. The diameter of the pore and the regularity of pore arrays can be adjusted by changing the chemical components and structures of the polymers and the correlative experimental parameters. Moreover, the thermal and chemical stabilities of the honeycomb-patterned porous polymer films can be improved for the practical applications with less limitation by two approaches, which include photo-cross linked process and utilizing hybridization of organic polymer with inorganic structures instead of pure organic polymer.In this paper, the surface morphology of the honeycomb-patterned films is characterized by the Scanning Electron Microscope (SEM). The results showed that the honeycomb-patterned films could be formed from the polymer with proper composition and concentration. The pore diameter increased with the hydrophilic block length and decreased with the polymer solution concentration increasing. And the appropriate solvent volatility was a key point for the formation of order structures.