Incorporating π-conjugated structures into organic polymers facilitates the construction of crystalline functional polymers with highly ordered structures. The high crystallinity, large specific surface area and excellent chemical stability of polymers facilitate significant potential for applications in gas adsorption and separation, heterogeneous catalysis, chemical sensing, photoelectric conversion, and energy storage. In our previous studies, through rational design of molecular building blocks, we developed a series of functional crystalline polymers with fluorescent response properties, which were successfully applied in the detection of metal ions, organic molecules, volatile compounds, and efficient iodine vapor capture. Furthermore, by employing flexible linking units and hydrogen-bond modulation strategies, we achieved a structural transition from amorphous to crystalline polymers, systematically elucidating the effects of external conditions—such as temperature, pH, and hydrogen bonding—on the self-assembly and crystallization mechanisms.

Based on previous work, this study aims to optimize the properties of crystalline polymers via structural regulation to expand their applications in electrical sensing. Through function-oriented molecular engineer with precise control over the electronic structure and hydrophilic sites of the building units, we successfully developed an ultrathin two-dimensional ordered crystalline polymer film. Featuring electron-rich triazine structure and hydrophilic hydroxyl groups, this material exhibits excellent electrical response characteristics. It demonstrates highly sensitive humidity detection with a wide linear range and ultrafast response/recovery time and has been effectively applied in real-time breath monitoring. This work not only deepens the understanding of structure–property relationships in 2D ordered crystalline polymers but also offers innovative design strategies for developing advanced optoelectronic polymer materials.