title: Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes.
abstract: A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O2 plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Junhe
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Xianying
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Guangping
authors.initials: G
authors.lastname: Zheng
keywords: Carbon nanotube; Composite membrane; Gas transport; Parylene