Synthesis of a Smart Hybrid MXene with Switchable Conductivity for Temperature Sensing

Inorganic–organic hybrid materials offer a wide variety of intriguing properties by combining their different characteristics and (chemical/physical) behavior, and the resulting smart materials find potential applications in areas such as energy technologies and drug delivery systems. Especially responsive two-dimensional carbides that belong to the class of MXenes benefit from this additional functionality in combination with their unique mechanical and electronic properties and bare potential for use as catalysts and sensors. Here, we therefore graft a stimuli-responsive polymer (poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA)) from the surface of a Ti-based two-dimensional carbide (MXene) using the OH groups on the MXene surface as a linker for the organic molecules. Successful fabrication of the hybrid material as well as covalent bonding between the inorganic component and the thermoresponsive polymer is shown by X-ray powder diffraction, IR and X-ray photoelectron spectroscopy, thermal analysis, and electron microscopy. We further demonstrate a reversible change of conductivity of thin films of this smart hybrid material using temperature as an external stimulus and enhance the mechanistic understanding by density functional theory (DFT) calculations. Such systems could therefore be used as temperature sensors in chemical reactions or microelectronics.