Photoresist is the key material in the fabrication of micropatterns or microstructures. Tuning the surface wettability of photoresist film is a critical consideration in its application of microfluidics. In this work, the surface wettability tuning of acrylic resin photoresist by oxygen plasma or ultra-violet/ozone, and its aging performance in different atmospheres, were systematically studied. The chemical and physical characterizations of the surfaces before and after modification show a dramatic decrease in the C-C group and increase in surface roughness for oxygen plasma treatment, while a decrease of the C-C group was found for the UV/ozone treatment. The above difference in the surface tuning mechanism may explain the stronger hydrophilic modification effect of oxygen plasma. In addition, we found an obvious fading of the wettability tuning effect with an environment-related aging speed, which can also be featured by the decrease of the C-C group. This study demonstrates the dominated chemical and physical changes during surface wettability tuning and its aging process, and provides basis for surface tuning and the applications in microfluidics.
Keywords: aging; contact angle; photoresist; wettability tuning.