Photo‐Modulating CO<sub>2</sub> Uptake of Hypercross‐linked Polymers Upcycled from Polystyrene Waste
Aotian Liu, Catherine Mollart, Abbie Trewin, Xianfeng Fan, Cher Hon Lau
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.