SiO₂-Coated Molecularly Imprinted Copolymer Nanostructures for the Adsorption of Bisphenol A

Molecularly imprinted hybrids (MIHs) were prepared by imprinting bisphenol A (BPA) molecules with linear polystyrene-co-methyl methacrylate chains followed by anchoring SiO₂ clusters onto the imprinted organic moieties. While the interior copolymer was responsible for BPA rebinding, the external SiO₂ layer confined the conformation of the copolymer, suppressed the nonspecific hydrophobic interactions, and enhanced the water compatibility of copolymer. Styrene and methyl methacrylate (MMA) were used as the dual functional monomers to interact with the BPA templates via π-πstacking interaction and formation of hydrophobic backbones, respectively. The optimal composition molar ratio of BPA/styrene/MMA/3-methacryloxylpropyltrimethoxysilane/tetraethyl orthosilicate with respect to the most satisfied adsorption ability was 1/2/5/5/15. The resulting MIH compound exhibited a superior adsorption performance, including a high imprinting factor of 14, a high adsorption capacity of 40.3 mg/g, a large association constant of 3.8 × 10⁴ M^-1, a short equilibrium time of 20 min, and high selectivity factors of 2-24 for BPA target over the other three endocrine-disrupting chemicals according to their sizes and geometries.