Synthesis, Characterizations and Colorimetric pH Sensors of Freestanding Janus Conjugated Covalent Organic Framework (COF) Films

A new mechanism of interfacial polymerization-interfacial film formation, based on the direct observation of the aqueous droplet volume change in the organic phase, is proposed. Depth profiling using X-ray photoelectron spectroscopy (XPS) revealed changes in the oxygen element composition after annealing, with a corresponding increase in hydrophilic groups exposed near the film's surface.

Capacitance tests demonstrated a slight decrease in capacitance after annealing, attributed to a lower percentage of oxygen elements. SEM analysis showed a slight increase in particle size after annealing. Additionally, Electron Spin Resonance (ESR) spectroscopy provided further validation, showing higher signal intensity in films treated with hydrochloric acid (HCl).