Thermoresponsive polymer brush photocatalytic substrates for wastewater remediation

Synthesis and characterization of a multi-responsive micron-scale heterogeneous catalyst are described. The temperature-responsive monomer N-isopropylacrylamide (NIPAAm) is copolymerized with the photo-active dye fluorescein o-acrylate (FlA) via surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization at varying thicknesses (i.e., molecular weights). The resulting poly(FlA-co-NIPAAm) copolymer brushes were found to undergo a rapid structural change between 24 and 26 °C, which significantly alters the photocatalytic behavior of the incorporated fluorescein. A wastewater treatment application was implemented to study the effect between temperature and film thickness. Notably, increasing the reaction temperature above the lower critical solution temperature (LCST) increased the performance in the degradation of tetracycline hydrochloride (TC) with the thickest of the photocatalyst polymer brushes showing the most pronounced temperature response.