Photo‐Modulating CO₂ Uptake of Hypercross‐linked Polymers Upcycled from Polystyrene Waste

Abstract

Abstract Incorporating photo‐switches into skeletal structures of microporous materials or as guest molecules yield photo‐responsive materials for low‐energy CO 2 capture but at the expense of lower CO 2 uptake. Here, we overcome this limitation by exploiting trans – cis photoisomerization of azobenzene loaded into the micropores of hypercross‐linked polymers (HCPs) derived from waste polystyrene. Azobenzene in HCP pores reduced CO 2 uptake by 19 %, reaching 37.7 cm 3 g −1 , but this loss in CO 2 uptake was not only recovered by trans – cis photoisomerization of azobenzene, but also increased by 22 %, reaching 56.9 cm 3 g −1 , when compared to as‐prepared HCPs. Computational simulations show that this increase in CO 2 uptake is due to photo‐controlled increments in 10–20 Å micropore volume, i. e., adsorption sites and a photo‐reversible positive dipole moment. Irradiating these HCPs with visual‐range light reverted CO 2 uptake to 33 cm 3 g −1 . This shows that it is feasible to recycle waste polystyrene into advanced materials for low‐energy carbon capture.