Poly(methylmethacrylate) (PMMA) has been widely used in the fields of optical instruments, aviation and auto industry, construction industry, advertising and decoration industry due to its optical transparency, low cost, low toxicity, and less fragile property. Recently it has been exploited to fabricate microfluidic chips. Region-selective metallization of PMMA surfaces are frequently required to improve the surface properties of PMMA and to integrate micro metal devices in PMMA microfluidic chips. This article presents our recent study on region-selective metalization of PMMA by means of UV/O₃-based surface modification in combination of region-selective electroless plating. Deep UV-lights, ozone, and deep UV-lights in cooperation with ozone were compared with respect to the efficiency of hydrophilization of the PMMA surface. It was observed with water contact angle measurements that only synchronized deep UV and ozone treatment can turn the PMMA surface from hydrophobic to hydrophilic effectively. Attenuated total reflection fourier transform infrared spectra revealed that polar moieties such as carboxyl groups were generated on the UV/O₃ treated areas. These polar moieties served as the anchors for further chemical reactions including amination of the carboxyl groups with ethylenediamine, adsorption of chloraurate anion onto the amine groups, and reduction of the Au(III) in the chloraurate anion to Au(0) by borohydride. These reactions led to the formation of the catalysis center of gold nano-particles on the UV-irradiated areas, which is indispensable for region-selective electroless plating. After optimization of the experimental conditions, a novel method for preparation of micro metal devices on PMMA surface has been established. With the printed poly(ethylene terephthalate) (PET) film serving as the primary photo mask, the achievable resolution of the prepared micro metal patterns was 50 μm or less. The deposited metal films adhered to the PMMA surface so strongly that they could hardly be tore off with adhesive tapes. Micro gold electrodes, micro gold electric heaters, micro copper electrodes, etc. were demonstrated to be prepared on PMMA surfaces, and their physical and electro-chemical properties were characterized.

Key words: poly(methylmethacrylate), region-selective metalization, UV/O₃, electroless plating