Tailoring the wetting properties of polymers from highly hydrophilic to superhydrophobic using UV laser pulses

This paper demonstrates the application of ultrashort-pulsed lasers as a unique tool for controllable modification of the surface wettability of polymers from high hydrophilicity to superhydrophobicity. This is achieved by exploiting the effect of laser pulse duration and photon energy on the surface chemistry and morphology and subsequent wetting properties of polymeric surfaces treated with UV laser pulses. In three different pulse duration regimes, ranging from femtosecond to nanosecond and two different photon wavelengths, we have systematically altered the wettability of polyethersulfone surfaces from highly hydrophilic to superhydrophobic. Our results indicate that, despite the remarkable changes in the surface morphology attained, the surface wettability variations are dominantly caused by laser-induced chemical modifications, which are highly dependent on the pulse energy and duration. The ability of tuning the wetting properties and thus the surface energy of laser-treated polymer surfaces within a broad range makes them excellent candidates for liquid flow control in microfluidics and biological adhesion applications.