LAUSR

Incorporating photo-switches into pores of microporous materials yield photo-responsive materials for low-energy CO2capture. However, such approaches reduce CO2 uptake of these materials. Here we overcome this limitation by exploiting trans-cis photoisomerization of azobenzene located in the pores of a hypercrosslinked polymer (HCP) derived from waste polystyrene to enhance CO2 uptake by 22 % when compared to pristine HCPs, reaching 56.9 cm3 g-1. Computational simulations show that this increase in CO2 uptake is due to photo-modulated pore widening effect and a positive dipole moment that enhanced CO2-azobenzene interactions. Vis-irradiating cis-HCPs@Azo reverted CO2 uptake to 33 cm3 g-1, like pristine HCP@Azo. This was attributed to a lack of a dipole moment and larger trans-azobenzene molecules reducing CO2 uptake in the smaller pores of trans-HCPs@Azo. This work shows the feasibility of recycling polystyrene waste into advanced materials for low-energy CO2 capture.