The effects of radio-frequency CF4 plasma on adhesion properties of vertically aligned carbon nanotube arrays

摘要

In this paper, vertical aligned carbon nanotube arrays (VACNTs) were modified by radio-frequency tetrafluoromethane (CF4) plasma for different times, and the corresponding adhesion performance of VACNTs was investigated. Scanning electron microscopy and Raman spectroscopy showed that the VACNTs remained intact alignment after CF4 plasma treatment, but the defects and amorphous carbon increased with increasing time. X-ray photoelectron spectroscopy showed that various functional groups were introduced with increasing time, such as C-O bonds, C=O bonds, semi-ionic covalent C-F bonds, covalent C-F bonds before 90 s, CF2=CF2 after 90 s. The water contact angle was drastically decreased before 90 s and then obviously increased until 180 s. The adhesion tests showed that the adhesion of the VACNTs firstly increased and then decreased, and the best adhesion strength of 29.3 N/cm(2) was obtained at 90 s, which improved about 39% compared with the pristine VACNTs. It can be seen that the polar/nonpolar groups plays a significant role on the adhesion behavior, and a great improvement of adhesion strength is obtained for the VACNT containing the polar groups on the surface after 90 s CF4 plasma treatment. (C) 2018 Elsevier Ltd. All rights reserved.