A molecularly imprinted polymer for the efficient adsorption of morphine

Molecularly imprinted polymers (MIPs) were synthesized via the precipitation polymerization technology for the specific adsorption of morphine. A number of polymers (methacrylic acid, trifluoromethyl acrylic acid, and acrylamide) were studied, respectively, as the precursor monomers under various synthetic conditions (the imprinting (IP) ratio, cross‐linking (CL) ratio, solvent ratio, reaction temperature, etc.). The MIP with optimal performance was derived using methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and azobisisobutyronitrile (AIBN) as the initiator, with an IP ratio of 1:3 and a CL ratio of 5:1. This MIP presented a maximum morphine adsorption capacity of 38.24 mg/g (one of the highest capacities ever reported in the literature) at a bulk morphine concentration of ~230 ppm in acetonitrile solution. The adsorption capacity, selectivity, reusability, as well as the chemical and mechanical stabilities of the MIP were confirmed by the adsorption experiments, instrumental characterization, thermodynamic analysis, as well as the proposed mechanisms. Schematic diagram for the synthesis of MIPMAA.