Solvent-Vapor-Induced Rapid Assembly of Block-Copolymer Film via Prevacuumizing

The undesired long time for the self-assembly of block-copolymer (BCP) thin films restricts their application as a template in lithography and other technologies. To shorten the assembly time, a facile but versatile strategy of solvent-vapor-induced rapid assembly into a uniform ordered morphology of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin film via prevacuumizing is reported. Factors such as the prevacuum pressure and the temperature during the solvent-vapor-annealing process are investigated for their effects on the assembly time. The morphologies are observed by transmission electronic microscopy (TEM) and the results indicate that the time for the assembly of PS-b-PMMA with a PS-cylinder-forming composition into a morphology of hexagonally arranged PS spheres in the film, induced by the solvent vapor at a prevacuum pressure 0.02 atm, is only 4 min at 20 degrees C and shortens more to 1 min at 60 degrees C.