Di-anisotropic conductive Janus-type film endued with super-paramagnetism and enhancive red fluorescence

Abstract

Fluorescent–conductive–magnetic multifunctional materials have wider applications than their counterpart single-functional materials. In this work, a newflexible twi-layer Janus-type film (TJF) with concurrence of di-anisotropic electrical conduction, super-paramagnetism and red fluorescence is designed and constructed via electrospinning. The unique TJF consists of two up-to-down layers closely bonded together; the up layer is an easily prepared non-array super-paramagnetic Fe3O4/polyvinylpyrrolidone nanofiber pellicle. The down layer is a Janus-type membrane with a left–right structure consisting of (polymethylmethacrylate (PMMA)/Eu(BA)3phen)║(PMMA/polyaniline (PANI)) Janus nanobelt arrays respectively used as the left and right halves. The conductive directions in the two halves are vertical, and the same is true with the insulative orientations, resulting in di-anisotropic conduction. The fluorescent color of the down layer is red under UV irradiation. In order to ensure high conductive anisotropy and enhancive red fluorescence, an exceptional Janus nanobelt is designed and applied as a conductive and building unit to construct the down layer. The critical thickness of the twi-layer multifunctional film is a vital parameter and studied for the first time. When the thickness of the up layer is determined, a corresponding critical thickness of the down layer will exist, and when the thickness of the down layer is fixed, a critical thickness of the up layer will also exist. No fewer than the critical thickness, the fluorescence properties of the down layer are not affected by the up layer. In this work,three kinds of special Janus structures are used to separate and confine different materials in their own domains at the microscopic and macroscopic levels, and microscopic and macroscopic partitions are simultaneously realized in TJF, leading to TJF with superior performance. Furthermore, TJF has excellent mechanical anisotropy. This work provides guidance for exploring the critical thickness and mutual effects of multi-layer multifunctional film.