Side Chain Functional Conjugated Porous Polymers for NIR Controlled Carbon Dioxide Adsorption and Release

Conjugated porous polymers exhibit considerable advantage as attractive candidate for carbon dioxide(CO₂) capture. However, the regeneration of the CO₂ still faces the problem of high energy cost. Here we synthesize a near-infrared region(NIR) light responsive conjugated porous polymer(PDPP-Gu) {DPP=3,6-di(thiophen-2-yl)pyrrolo3,4-c]pyrrole-1,4(2H,5H)-dione} by constructing porous amorphous networks with a side chain engineering strategy to regulate CO₂ adsorption and release through photothermal conversion. The PDPP-Gu is featured by a torsional conjugated backbone as well as a functional side chain of guanidino group. The donor-acceptor configuration of PDPP-Gu afforded strong absorption in the NIR and an excellent photothermal conversion capability of up to 48.8%, as well as a high surface energy. Moreover, guanidine modified side chain further enhanced the CO₂-polymers interactions, resulting in a high CO₂ selective adsorption capacity(0.8 mmol/g) at 273 K, 1 bar(1 bar=10⁵ Pa). The adsorbed CO₂ can be released under NIR light irradiation. This strategy of molecule design combined the dual features of photothermal conversion and gas adsorption, which is beneficial for the development of materials to dynamically control the adsorption and release of CO₂ through NIR light.