Surface patterning of polychloromethylstyrene films

We describe and characterize a simple process for the fabrication of patterned materials on polychloromethylstyrene thin film surfaces under ambient conditions. Patterned deep UV exposure (approximately 60 mJcm(-2), 193 nm) efficiently oxidizes the surface C-Cl bonds of the polymer film, producing an aldehyde species as the major photoproduct. Reductive amination in the presence of ammonium ion and cyanoborohydride reductant selectively converts the aldehyde into an alkylamine, which leads to an amine reactivity template on the film surface. The amines formed are sufficiently reactive to selectively and covalently bind fluorescent dye or electroless Ni metal to the template, which results in negative tone features with micron-scale resolutions (mask limited) in each case. Spectroscopic characterizations of the polymer surface following the photochemical transformation, reductive amination, and grafting steps are presented in support of the process. A key advantage of the method is the use of safe solvents, such as water or simple alcohols, to effect the reductive amination and grafting reactions. This approach mitigates waste disposal and associated environmental concerns, increasing the attractiveness of our method for use with high-throughput track-line processing equipment.