Elaboration and characterization of molecularly imprinted polymer films based on acrylate for recognition of 2,4-D herbicide analogue

This work comprises an elaboration of novel molecularly imprinted polymers (MIPs) films by non-covalent approach in presence of phenoxypropionic acid (PPA) as an analogue of 2,4-D herbicide. MIPs were prepared by photo-polymerization of a mixture containing the n-butyl acrylate (BuA) as monomer, 1,6 hexanediol diacrylate (HDDA) as cross-linker, PPA as template, 2-hydroxy-2-methyl-1-phenyl-propane-1-one as photoinitiator and chloroform as porogenic solvent. The computer modelling and 1 H NMR analysis confirmed the presence of non-covalent hydrogen-bonding interactions between the template molecule and the monomer in pre-polymerization complex. Imprinted and non-imprinted polymers (NIPs) were characterized by infra-red spectroscopy (IR), thermogravimetric analysis (TGA) and atomic force microscopy (AFM) techniques. The template extraction from MIP and the recognition properties of NIPs and MIPs were performed by gas chromatography (GC). The binding characteristics of MIPs, after removing the template were evaluated using equilibrium binding experiment and compared them with the corresponding NIPs. To acquire a maximum specific binding, factors such as the amount of polymer film, template concentration and cross-linking density were varied. In all cases, the binding experiment showed that the PPA imprinted polymer had better recognition ability than the non-imprinted polymer. As a result, MIP gave higher imprinting effect at higher cross-linking density and lower PPA concentration when using 6 mg of polymer film mass. The resulting dummy MIPs exhibited selective recognition and satisfactory adsorption capacities of 2,4-D in the solvent used for polymerization. Graphical abstract