title: Surface Wettability Modification of Cyclic Olefin Polymer by Direct Femtosecond Laser Irradiation.
abstract: The effect of laser irradiation on surface wettability of cyclic olefin polymer (COP) was investigated. Under different laser parameters, a superhydrophilic or a superhydrophobic COP surface with a water contact angle (WCA) of almost 0° or 163°, respectively, could be achieved by direct femtosecond laser irradiation. The laser power deposition rate (PDR) was found to be a key factor on the wettability of the laser-treated COP surface. The surface roughness and surface chemistry of the laser-irradiated samples were characterized by surface profilometer and X-ray photoelectron spectroscopy, respectively; they were found to be responsible for the changes of the laser-induced surface wettability. The mechanisms involved in the laser surface wettability modification process were discussed.
authors.affiliation: SIMTech-NTU Joint Laboratory (Precision Machining), Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. wangbing@ntu.edu.sg.|School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. wangbing@ntu.edu.sg.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.affiliation: SIMTech-NTU Joint Laboratory (Precision Machining), Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. xcwang@simtech.a-star.edu.sg.|Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore. xcwang@simtech.a-star.edu.sg.
authors.forename: Xincai
authors.initials: X
authors.lastname: Wang
authors.affiliation: SIMTech-NTU Joint Laboratory (Precision Machining), Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. hyzheng@simtech.a-star.edu.sg.|Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore. hyzheng@simtech.a-star.edu.sg.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zheng
authors.affiliation: SIMTech-NTU Joint Laboratory (Precision Machining), Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. myclam@ntu.edu.sg.|School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. myclam@ntu.edu.sg.
authors.forename: Yee Cheong
authors.initials: YC
authors.lastname: Lam
keywords: cyclic olefin polymer (COP); femtosecond pulsed laser; laser power deposition rate (PDR); surface modification; wettability