Electrospun polyfunctional conductive anisotropic Janus-shaped film, derivative 3D Janus tube and 3D plus 2D complete flag-shaped structures

Abstract

A new type of two-dimensional (2D) di-layer Janus-shaped film (named as DJF) with synchronous polyfunctions of superparamagnetism, dual anisotropic electrical conduction and green-red dual-colored luminescence was devised and synthesized via an electrostatic spinning technique. Macroscopically, the 2D DJF comprises two layers closely bonded together, a Janus pellicle with a left–right structure as the first layer and non-array luminescent membrane as the second layer. Microscopically, the first layer consists of a [polyaniline (PANI)/polymethylmethacrylate (PMMA)]//[PMMA/Fe₃O₄] Janus nanoribbon array as the left region and [PANI/PMMA]//[PMMA/Tb(BA)₃phen] Janus nanoribbon array as the right region, while single conductive anisotropy exists in both the left and right regions, resulting in dual conductive anisotropy of the first layer. The second layer is made up of [Eu(BA)₃phen/PMMA] unordered nanofibers. The right region of the first layer exhibits green luminescence, while the second layer emits red luminescence, affording a 2D DJF with red-green dual-colored luminescence. Furthermore, the DJF has excellent mechanical anisotropy. The 2D DJF was rolled into three-dimensional (3D) Janus tubes and 3D plus 2D complete flag-shaped structures using different rolling schemes to obtain four types of Janus tubes and twelve types of complete flag-shaped structures. A new concept of a complete flag-shaped structure is presented for the first time and its peculiar structure reflects the successful combination of a 2D film with a 3D tube. The new 3D or 3D plus 2D materials exhibit similar excellent properties to those of the 2D DJF. Moreover, the structures and different features of the 3D or 3D plus 2D materials can be modulated by changing the properties of the different functional areas and the arrangement of the Janus nanoribbons. Highly integrated polyfunctions in a single material with variable characteristics are achieved. The design philosophy and techniques offer support to fabricate new-type polyfunctional nanostructured materials.