Highly Ordered and Multiple-Responsive Graphene Oxide/Azoimidazolium Surfactant Intercalation Hybrids: A Versatile Control Platform

To produce graphene materials with better controllability, a new graphene oxide (GO) intercalation hybrid is fabricated with the incorporation and functionalization with the azoimidazolium (AzoIm⁺) surfactant. The hybrid exhibits a highly uniform lamellar structure in which a few layers of GO are stacked with AzoIm⁺ alternatively. Simultaneous control of the mesoscopic structures, aggregation properties, and electrochemical behavior of the hybrid is achieved by inheriting the photo, thermal, and mechanical responsiveness of azoimidazolium. Ultraviolet (UV) treatment produces a well-dispersed GO/AzoIm⁺ suspension aggregate and a precipitate, whereas the specific capacitance of the final hybrid decreases. The lamellar stacking becomes anisotropic by uniaxial stretching on a soft polymer. With a liquid crystal unit inserted between the layers, the <i>d</i> spacing of the lamella passes through transformation, disordering, and finally recovery stages, associated with the increasing and decreasing temperature. The explosive release of heat generated by the thermal reduction of GO is reduced in the GO/AzoIm⁺ intercalation hybrid. The release of heat is tunable by varying the relative quantity and UV treatment of AzoIm⁺. The physical properties of the hybrid allow the controlled preparation of ultrasmall Au nanodots between the GO layers. This represents a major step toward multiple-responsive integrated graphene applications

Electrothermally Driven Fluorescence Switching by Liquid Crystal Elastomers Based On Dimensional Photonic Crystals

In this article, the fabrication of an active organic–inorganic one-dimensional photonic crystal structure to offer electrothermal fluorescence switching is described. The film is obtained by spin-coating of liquid crystal elastomers (LCEs) and TiO₂ nanoparticles alternatively. By utilizing the property of LCEs that can change their size and shape reversibly under external thermal stimulations, the λ_max of the photonic band gap of these films is tuned by voltage through electrothermal conversion. The shifted photonic band gap further changes the matching degree between the photonic band gap of the film and the emission spectrum of organic dye mounting on the film. With rhodamine B as an example, the enhancement factor of its fluorescence emission is controlled by varying the matching degree. Thus, the fluorescence intensity is actively switched by voltage applied on the system, in a fast, adjustable, and reversible manner. The control chain of using the electrothermal stimulus to adjust fluorescence intensity via controlling the photonic band gap is proved by a scanning electron microscope (SEM) and UV–vis reflectance. This mechanism also corresponded to the results from the finite-difference time-domain (FDTD) simulation. The comprehensive usage of photonic crystals and liquid crystal elastomers opened a new possibility for active optical devices