Insight into the impact of N,N′-methylenebisacrylamide as crosslinker in the design of an ion-imprinted polymer for selective adsorption of copper(II)

The impact of the crosslinker on the performances of an ion-imprinted polymer (IIP) designed for copper(II) selective recognition was investigated by changing the classical ethylene glycol dimethacrylate (EGDMA) crosslinker to N , N ′-methylenebisacrylamide (MBA). MBA was chosen for its more hydrophilic character which allows the preparation of the IIP in water, and could thus favour the interactions of the IIP with the target ion in aqueous samples. A copper(II)-IIP, and its corresponding non-imprinted polymer (NIP), were prepared by precipitation polymerisation in water with MBA and methacrylamido-L-histidine (MAH), as an amino acid-inspired functional monomer. For the purpose of comparing the structural and binding properties of the IIP-MBA and the NIP-MBA, another control polymer (poly(MBA- co -AAm)) was also synthesised by replacing MAH by acrylamide (AAm). As expected, the use of MBA as a crosslinker increased the hydrophilicity of the IIP-MBA and NIP-MBA. However, the sorption capacity of the IIP-MBA for copper(II) was quite close to those of the NIP-MBA and poly(MBA- co -AAm) at around 40 μmol/g, despite major differences between the measured surface areas (12.2 vs 149.5 and 211.8 m 2 /g, leading to relative adsorption capacities of 3.3 μmol/m 2 for the IIP-MBA and 0.27 μmol/m 2 for the NIP-MBA). The IIP-MBA and NIP-MBA showed excellent selectivity towards copper(II) compared to iron(III) lead(II) and zinc(II), with selectivity coefficients ranging from 4 to 100, compared to poly(MBA- co -AAm). These results emphasise the positive effect of MAH on selective copper(II) adsorption. They also highlight the importance in crosslinking agent choice and its impact on textural and adsorption properties of the corresponding IIP. • Use of acrylamide-based monomers for Cu(II)-imprinted polymers synthesis. • Selective adsorption of Cu(II) with methacrylamido-L-histidine based imprinted polymer. • Study of the influence of the hydrophilicity of the crosslinker. • Identification of polymer swelling as a crucial parameter for maintaining binding cavities.