Surface Modification of Polymethylmethacrylate (PMMA) by Ultraviolet (UV) Irradiation and IPA Rinsing

Polymethylmethacrylate (PMMA) is commonly applied to microfluidic devices due to its excellent biocompatibility, high optical transparency, and suitability for mass production. Recently, various surface treatment methods have been reported to improve the wettability of polymers, which is directly related to adhesion. In this research, the effect of a UV irradiation technique and an IPA rinsing technique as surface treatments for PMMA is investigated regarding the water contact angle of the PMMA surface. PMMA sheets that were 1.62 mm thick and commercially available were exposed to UV light with four different exposure times. Significant decreases in the water contact angle were observed after exposure to UV light, and the lowered contact angles due to the UV irradiation increased over time. According to the measurement, the water contact angle is a function of UV exposure dose as well as storage time after UV exposure. We examined the effect of a IPA rinsing process after UV irradiation and observed an increase in the water contact angle.