Imine-Linked 2D Conjugated Porous Organic Polymer Films for Tunable Acid Vapor Sensing

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Two-dimensional (2D) conjugated porous organic polymers (C-POPs) offer promising optical and electronic functionalities but face challenges in processability and large-area film fabrication.
• Existing methods often lack facile, single-step routes for producing high-quality 2D-C-POP films, hindering their practical applications.
• Developing scalable synthetic strategies for robust 2D-C-POP films is crucial for advancing device architectures.

Purpose of the Study:

• To report a facile, single-step synthetic route for mechanically robust, free-standing 2D-C-POP films.
• To investigate the gas sensing capabilities of these novel C-POP films, particularly for volatile acid gases.
• To explore the potential of these films in micro-optical and triboelectric devices.

Main Methods:

• Synthesis of four imine-linked 2D-C-POP films via a scalable, tunable, single-step condensation reaction.
• Characterization of film structure, including exfoliable 2D nanosheets (NSs) and anisotropic properties.
• Evaluation of colorimetric sensing performance for hydrogen chloride (HCl) gas, including sensitivity, response time, and recyclability.
• Computational modeling to elucidate structure-property relationships in sensing.

Main Results:

• Successful synthesis of mechanically robust, free-standing 2D-C-POP films with tunable properties.
• Films demonstrated ultraresponsive colorimetric sensing of HCl gas down to 0.05 ppm, significantly below safety limits.
• The C-POP films exhibited fast response times, good recyclability, and potential for integration into micro-optical and triboelectric devices.
• Anisotropy and exfoliable nanosheet structure were confirmed, contributing to optoelectronic properties.

Conclusions:

• The developed single-step synthesis provides a scalable route to high-quality 2D-C-POP films with enhanced stability and accessibility.
• These C-POP films are highly effective ultraresponsive colorimetric sensors for acid gases, surpassing existing benchmarks.
• The tunable conjugation, nitrogen centers, and porous architecture are key to the sensing performance, validated by computational insights.
• The films' unique properties enable their application in advanced sensing devices and optoelectronics.