Design and synthesis of thiophene containing bis-chalcone-based mesoporous polymers for volatile iodine capture

Abstract

Two novel thiophene-containing bis-chalcone-based polymers poly [(1E,4E)-1,5-Di-2-thienylpenta-1,4-dien-3-one] (PTCA) and poly[(1E,4E)-2,4-dimethyl-1,5-di(thiophen-2-yl)penta-1,4-dien-3-one] (PTCM) were designed and synthesized by FeCl3 mediated oxidative coupling polymerization reaction. The formation of polymers was confirmed by FT-IR and UV-DRS analysis, and the structural and morphological characterizations were done by PXRD, SEM, TEM, TGA, CHNS, and BET analysis techniques. Owing to their mesoporous nature, and excellent thermal and chemical stability, they found significant applications in the field of environmental remediation. Regardless of their low surface area, they emerged as strong candidates for the iodine capture process due to the presence of electron-rich heteroatoms. The maximum iodine capture capacity obtained for PTCA and PTCM were 242 and 221 wt.% respectively. The kinetic study revealed that the adsorption of iodine onto the polymers fit well in the pseudo-second-order kinetic model with a correlation coefficient R2 > 0.99, pointing to the chemisorptive nature of adsorption. The polymers can be competently recycled and reused even after five cycles without a significant loss of iodine uptake. After the first cycle, the iodine release efficiency was as high as 89% and 93% for PTCA and PTCM respectively. The iodine uptake capacity of the reused polymers PTCA and PTCM was found to be 89.2% and 86.5% respectively after five successive cycles. And these materials offer the benefits of facile, low-cost, large-scale, and template-free synthesis of mesoporous polymers. This study also provides an opportunity for the design same kind of polymers with different heteroatoms and functional groups.