Fabrication And Photocrosslinking Of Poly(Glycidyl Methacrylate) Honeycomb Film

Honeycomb-patterned highly regular porous film could be formed by using hexagonally close-packed water droplet arrays as template in humidity environment. However, despite the apparent simplicity of the patterning method, the actual obtained honeycomb films are extremely sensitive to organic solvents and elevated temperature which limited the applications of the film in harsh environments. Usually, cross-linking is a common and efficient method in the modification of the film. Photochemical cross-linking is an attractive technique because it is easier to perform and high efficiency, while leaves little or no contamination. In this subject, highly ordered honeycomb patterned film of poly(Glycidyl methacrylate) (PGMA)was successfully fabricated via a one-step static Breath Figure process, and then crosslinked through a cationic photopolymerization.1. PGMA with varied molecular weight was fabricated through thermal radical polymerization, which was further used to fabricate highly ordered honeycomb film via a one-step static Breath Figure process by regulating various parameters in the process. Morphology of the porous film was observed by SEM. It turned out that solvent play a vital role on formation of porous structure, in this subject, solvent of CH2Cl2 and CHCl3 in the proportion of 70:30 (v/v) is good candidate for honeycomb formation;Meanwhile, PGMA with molecular weight around 15K, 45K, 100K and proper concentration can be used to fabricate regular porous film. And the pore size is proportional to the relative humidity.2. Afterwards, the patterned film was further modified to enhance the solvent resistance as well as thermal stability through crosslinking the epoxy group via cationic photopolymerization. Morphology of the film was observed by SEM and AFM. Compared with uncrosslinked porous film, the crosslinked film preserved the 3D structure of the original honeycomb film and could withstand a variety of solvents, such as CH2Cl2,CHCl3,THF,acetone et al., for at least one week and the thermal stability was improved 150℃.3. The micro-patterns was then used as template to assemble SiO2 particles via chemical vapor deposition at mild condition. FTIR indicated that the crosslinked film presented lots of hydroxyl group which played a vital role in linking of SiO2 particles on the membrane. Under high temperature, the honeycomb film was burned up and the silica particles were sintered into SiO2 microbowl array. The morphology of the bowl was tunable by varying the structure of the obtained template. After peeling off the surface layer, the obtained pincushion film can be used as template for the fabrication of microdisks.