Corona Discharge-Induced Functional Surfaces of Polycarbonate and Cyclic Olefins Substrates

Functional surfaces have great significance for improving the performance of bio-devices. The selection of appropriate ways to functionalise the surfaces of the polymers used for bio-devices are in great demand. In particular, cyclic olefin copolymer (COC) and cyclic olefin polymers (COP) are emerging substrates for bio-devices and possess superior chemical resistance than other polymeric substrates such as polycarbonate (PC). These polymer substrates often require surface modification to provide the functionality required. Here, we present a means to functionalise the surfaces of these polymers by a corona discharge treatment method. The water contact angle (WCA) of as received PC, COC and COP was found to be around 80°, 96° and 93°, respectively. The WCA of PC, COC and COP is reduced by 40%, 46% and 44%, respectively when treated with corona dose of 95 W min/m2. The WCA of PC, COC and COP was further reduced by increasing the corona dosage. The reduction of WCA is found mainly due to the incorporation of oxygen-related functionalities (such as carboxylic, carbonyl or aldehyde groups) as confirmed by high-resolution X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary mass spectrometry (ToF-SIMS). The oxygen to carbon (O/C) ratio is clearly increased after the corona treatment confirming the depletion of carbon on the functional surfaces. The functionality of surfaces obtained by corona treatment could be useful in the development of new bio-devices.