Alternating aligned conductive stripes in polypropylene film with remarkable anisotropy for sensing application

Abstract

Abstract Anisotropic conductive films (ACFs) are of great significance in miniaturized sensing devices, however it still is a huge challenge to fabricate ACFs via a facile and cost-effective method. Herein, ACFs containing aligned conductive stripes have been developed based on polypropylene (PP)/multi-walled carbon nanotubes (MWCNTs) composite. Compared with their isotropic counterparts, they demonstrate quick response, high responsivity and excellent reversibility for volatile organic vapors. The maximum responsivity toward three organic vapors is in the order of cyclohexane > dichloromethane > ethyl acetate, which is consistent with the calculated Flory-Huggins interaction parameter. The superior organic vapor sensing behavior of anisotropic PP/MWCNTs film (A-P/M-F) can be ascribed to the clear interfaces between stripes, which can accelerate the rapid absorption/desorption of vapors at such interfaces. Moreover, the spatial confining forced effect between the neighboring stripes is beneficial for reconstructing and stabilizing the internal conductive network, endowing A-P/M-F containing aligned conductive stripes with a good sensing stability. Furthermore, their vapor sensing behavior shows temperature dependence, that is, it increases with the increasing temperature because of higher absorption activation energy at higher temperature. This work provides a facile but cost-effective way to fabricate ACFs, enabling its industrial-scale application as organic vapor sensor with high stability and satisfied reliability.