A neoteric sandwich-configurational composite film offering synchronous conductive aeolotropy, superparamagnetism and dual-color fluorescence

Abstract

A new type of two-dimensional (2D) sandwich-configurational composite film offering electrically conductive aeolotropism, superparamagnetism and dual-color fluorescence was successfully fabricated via electrospinning. The composite film consists of a [polyaniline (PANI)/polymethylmethacrylate (PMMA)]//[Eu(BA)₃phen/PMMA] Janus nanobelt array aeolotropic conductive-fluorescent layer (first layer), a Fe₃O₄/polyvinylpyrrolidone (PVP) superparamagnetic nanofibers layer (second layer) and a Tb(BA)₃phen/polyacrylonitrile (PAN) fluorescent nanofiber layer (third layer), which have been tightly bonded together to form a sandwich-configurational composite film with trifunctionality. Because of the exceptive sandwich-like structure, electrically conductive, superparamagnetic, and fluorescent substances are mutually and efficaciously segregated. Thus, reciprocally pernicious interferences among them can be thoroughly avoided; thus, the sandwich-configurational composite film coinstantaneously possesses superior conductive aeolotropism, fluorescence and magnetism tri-functionality. Thus, the aeolotropic conductive-fluorescent layer and fluorescent layer respectively exhibit excellent red and green fluorescence properties. Further, the conductive aeolotropism and superparamagnetism of the composite film can be severally adjusted via regulating the contents of PANI and Fe₃O₄ NPs. Owing to the peculiar nanostructure made of Janus nanobelts in the aeolotropic conductive-fluorescent layer, the conduction ratio reaches 10⁸ times between conductive and insulating directions of the sandwich-configurational composite film. Under the excitation of 290 nm ultraviolet light, prominent red emission at 615 nm can be clearly observed in the aeolotropic conductive-fluorescent layer. Additionally, major green emission at 545 nm can be observed in the fluorescent layer under 314 nm light excitation. Furthermore, due to the exceptional sandwich structure, the properties of each layer of the whole film are relatively independent, the fluorescence intensities of the aeolotropic conductive-fluorescent layer and the fluorescent layer are hardly affected by the magnetic variation of the superparamagnetic layer, and the fluorescence intensity of the fluorescent layer is not influenced by the modulation of the PANI content of the aeolotropic conductive-fluorescent layer. The neoteric sandwich-configurational composite film with concurrent trifunctionality constructed by a facile method has potential applications in many fields. Overall, the academic design and manufacturing means will provide support for the design and construction of new-typed aeolotropic conductive films with multifunctionality.