Hydrophilization of Amorphous Perfluoropolymer using Low-pressure Argon Plasma

Abstract

The amorphous perfluoropolymer CytopTM (Asahi Glass Co., Ltd.) is an attractive material for use in microdevices for biological and chemical analysis because of its high optical transparency, excellent chemical stability, and low refractive index of 1.34, which is almost the same as that of water. In this study, to increase the applicability of this polymer for such microdevices, the modification of its surface properties was investigated using low-pressure argon plasma. Hydrophilicity control with a water contact angle in the range from 30° to 110° and, moreover, the long-term stability of the hydrophilized surface were achieved for the first time. Although oxygen plasma treatment caused etching instead of hydrophilization, exposure to argon plasma led to bond breaking, the formation of free radicals, and finally the incorporation of hydrophilic groups as a result of the reaction with the oxygen or water from the atmosphere after the polymer was removed from the plasma reactor. Furthermore, to evaluate the suitability of this material for applications involving cell cultivation, the cell adhesion and proliferation properties of the plasma-treated surface were also investigated.