title: Fabrication of directional nanopillars with high-aspect-ratio using a stretching imprint process with a microcavity mold.
abstract: Directional nanopillars with high-aspect-ratio have wide applications in home or industrial appliances and biomimetic robots. Their fabrication, however, is a challenge for conventional methods. In this study, we propose a simple stretching imprint process to prepare controllable directional (30°-90° in a slanted angle) nanopillars (200-800 nm in diameter) with high aspect ratio (>30) using a microcavity mold, beyond the conventional nanoimprint process, for 1 : 1 pattern transfer from the mold to the replica. The mechanism of the stretching imprint process is further investigated, and a rheology model for the filament evolution during the stretching process is established, which clearly shows that the aspect-ratio, diameter in submicrons, slanted angle, and also the tip profile of the free-standing nanopillars can be easily controlled by the imprint process using a microcavity mold. Further experiments indicate that the fabricated directional free-standing nanopillars show strong friction anisotropy, which may find applications in biomimetic studies.
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Weitao
authors.initials: W
authors.lastname: Jiang
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Biao
authors.initials: B
authors.lastname: Lei
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Hongzhong
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Niu
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Bangdao
authors.initials: B
authors.lastname: Chen
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Yin
authors.affiliation: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China. wtjiang@mail.xjtu.edu.cn hzliu@mail.xjtu.edu.cn.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Engineering Research Center of Mechanical Testing Technology and Equipment, Chongqing University of Technology, Chongqing 400050, China.
authors.forename: Xiaokang
authors.initials: X
authors.lastname: Liu