Nanofibrillar, Heteroatom-Rich Triphenylamine-Based Conjugated Microporous Polymers for Selective Dye Capture and Iodine Uptake

Abstract

Developing effective materials for eliminating harmful contaminants is crucial for environmental remediation. In this study, we explore two triphenylamine-based conjugated microporous polymers, PTPA-IDT and PTPA-DMQ, by incorporating s-indaceno[1,2-b:5,6-b′]-dithiophene-4,9-dione (IDT) and N,N-dimethyl quinacridone (DMQ) units into the polymer backbone for the first time, which serve as an efficient multifunctional platform for the adsorption of dyes and iodine. By altering the core building block, we successfully tuned their porous properties and morphological features which in turn enhanced their adsorption capabilities. PTPA-IDT, characterized by its nanofiber-like morphology and higher surface area, demonstrated impressive removal capabilities for methylene blue (MB) and rhodamine B (RhB) dyes from polluted water, achieving maximum adsorption capacities of 241.5 mg/g and 125.3 mg/g, respectively. Interestingly, PTPA-DMQ demonstrates rapid adsorption kinetics for MB with a pseudo-first-order rate constant of 0.031 s^–1 and exhibits remarkable selectivity for MB over RhB in a mixture, as supported by DFT calculations revealing that RhB adsorption is thermodynamically unfavorable. Furthermore, both CMPs effectively removed iodine vapor, showcasing a promising iodine uptake capacity of 3.87 and 3.24 g/g for PTPA-IDT and PTPA-DMQ, respectively. Recyclability tests revealed that the CMPs exhibit excellent reusability for the dyes and iodine adsorption, maintaining their adsorption capability effectively through the sixth cycle without significant loss. Our findings indicate that these low-cost, metal-free synthetic CMPs hold significant potential for treating polluted water and capturing iodine effectively.