The preparation and characterization of photo-responsive sol–gel materials for 2,4-dichlorophenoxyacetic acid by surface imprinting

Abstract The primary objective of this work is to develop a photo - responsive surface molecularly imprinted polymer (SMIP) for 2,4 - dichlorophenoxyacetic acid (2,4 - D) to overcome the shortcomings of conventional molecularly imprinted polymers. A photo - responsive functional monomer was firstly prepared by covalent connecting azobenzene and 2,4 - D. The photo - responsive SMIP was then prepared on SiO 2 nanoparticles via sol–gel process, and 2,4 - D was removed via hydrolysis in acid. The SMIP shows specific affinity to 2,4 - D and reversible uptake and release of 2,4 - D upon alternate irradiation at 365 and 440 nm, respectively. The favorable binding strength of the imprinted receptor sites in the SMIP for 2,4 - D is found to be 2.51 × 10 4  M −1 . Density of receptor sites in the SMIP material is 10.59 μmol/g SMIP. The SMIP requires a shorter time to reach equilibrium than does the conventional molecularly imprinted polymer. The well - defined core - shell structure was clearly visualized by high resolution transmission electron microscopy. Graphical Abstract