Electrospun light stimulus response-enhanced anisotropic conductive Janus membrane with up/down-conversion luminescence

Abstract

Herein, the concept of a light stimulus response-enhanced anisotropic conductive Janus membrane (named L-ACJM) is proposed for the first time, and a new strategy of combining photoconduction with anisotropic conduction to improve the anisotropic conductive degree of materials is introduced. Here, we prepared L-ACJM with a top-bottom structure via bi-axial parallel electrospinning combined with uniaxial electrospinning using an arrayed [polyaniline (PANI)/2,7-dibromo-9-fluorenone (DF)/polymethyl methacrylate (PMMA)]//[Eu(TTA)₃(TPPO)₂/PMMA] Janus nanobelt and non-arrayed [NaYF₄:Yb³⁺, Tm³⁺/polyacrylonitrile (PAN)] nanofiber as constructive units. In the absence of light, L-ACJM exhibited anisotropic conductivity. In contrast, under light irradiation, L-ACJM exhibited enhanced anisotropic conductivity and up/down-conversion dual-mode luminescence. Due to the photoconductive effect of DF, the conductivity and level of anisotropy of L-ACJM could be modulated by light irradiation. The effect of different DF/PANI mass ratios on the photoconductivity of the products was studied and the interaction mechanism was revealed. By combining a photoconductive substance with anisotropic conductive membranes, optically controlled adjustable anisotropic conductive properties could be realized and the functionality of type II anisotropic conductive membranes could be extended. Simultaneously, an up-conversion luminescent material (NaYF₄:Yb³⁺, Tm³⁺) was introduced in anisotropic conductive membranes to realize the versatility of L-ACJM. Adjustable yellow-red and green luminescence was obtained by changing the doping amount of Eu(TTA)₃(TPPO)₂ and NaYF₄:Yb³⁺, Tm³⁺ or the excitation wavelength. High anisotropic photoconductivity and luminescence of L-ACJM were ensured by using Janus nanobelts at the micro level, and the mechanical property of L-ACJM was enhanced using the top-bottom Janus structure membrane at the macro level. This design idea and construction technology provide theoretical and technical support for the development of new anisotropic conductive films and multifunctional nanostructured materials.