Interaction of Polar and Nonpolar Polyfluorenes with Layers of Two-Dimensional Titanium Carbide (MXene): Intercalation and Pseudocapacitance

This article provides insight into the interaction of synthetic conjugated polymers [polyfluorene derivatives (PFDs)] with layers of two-dimensional titanium carbide (Ti₃C₂T_x). Three derivatives with nonpolar, polar, and charged nitrogen-containing functionalities were synthesized via the Suzuki polycondensation reaction. The organic-inorganic PFD/Ti₃C₂T_x hybrids were prepared and characterized using X-ray diffraction and a range of microscopic and spectroscopic techniques to elucidate the host-guest interaction mechanism. We show that polar polymers with charged nitrogen-containing ends have the strongest interaction with the Ti₃C₂T_x layers, yielding an increase in interlayer spacing and large shifts in spectroscopic peaks. Furthermore, the effect of polymer backbone juxtaposition between Ti₃C₂T_x layers on pseudocapacitance is discussed in detail. Our results suggest that new organic materials capable of intercalation between the layers of Ti₃C₂T_x and other MXenes may be used in the design of hybrid structures for high-performance energy storage applications and beyond.