Hydrophilic surface formation on materials and its applications

A new surface modification technique, ion assisted reaction (IAR) has been developed at the Korea Institute of Science and Technology (KIST) ion beam laboratory for modifying the surfaces of polymers. IAR, in which a kiloelectron volt ion beam is irradiated on the surface of a polymer in a reactive gases environment, has been developed for improving wettability of materials and enhancing adhesion to other materials. The contact angles of water drops with modified polymers were reduced more by Ar+ ion irradiation with a flowing oxygen gas environment than without flowing oxygen gas. The change in contact angles for the modified polymers was explained by a two-step chemical reaction between the polymer matrix, energetic ions and oxygen gas. X-Ray photoelectron spectrometry (XPS) showed that hydrophilic groups were formed on the surface of polymers by chemical reaction between the unstable chains induced by ion irradiation and the oxygen gas, and the hydrophilic groups were identified as –(CO)–, –(CO)– and –(CO)O– bonds. The enhanced adhesion between metal and modified polymers was explained by the formation of electron acceptor groups in polymer and electron donors in metal.