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Functional microspheres with subtle designed molecular recognition sites is much highlighted in recent days. We here study the in situ molecular imprinting in the Stöber synthesis of resorcinol-formaldehyde (RF) microspheres, and two different approaches are demonstrated. One approach is named as organic molecular imprinting, during which the target molecules of bisphenol A (BPA) are incorporated as the template in the gelation of RF resin. The other is named as inorganic molecular imprinting, during which the template is introduced together with inorganic precursor of titanate. The sizes of the produced spheric particles are found to rely on the ratio of ethanol/water in the reaction medium. Recognition sites which are BPA specific have been detected on both the RF and RF-carbon/TiO 2 spheres, and the latter show slightly higher capacity and selectivity in rebinding tests. Importantly, the integration of the photo active nano TiO 2 on the submicron spheric carbon support with BPA imprinted sites is of unique advantages, which exhibits as the specific high photocatalytic efficiency on BPA degradation under UV light. This, together with the high selectivity, substantial efficiency and operable uniform size of the composite spheres would be useful in the engineering for environmental and analysis fields. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic illustration for the synthesis of SHH-MIP particles by miniemulsion polymerization Highlights • Miniemulsion polymerization is performed to synthesize MIP particles. • The obtained MIP particles exhibit single hole hollow structure. • MIP show fast adsorption kinetics with the t 1/2 of 4.35 min. • MIP display excellent binding capacities and accurate recognition specificity. Abstract The structural design on the molecularly imprinted polymers (MIP) has been increasingly concerned because of advanced recognition efficiency. We here demonstrate a facile miniemulsion based polymerization to synthesize single hole hollow MIP particles for the recognition of bisphenol A (BPA). Uniform submicron products can be achieved through one-step polymerization in the aqueous dispersion, where the polymer seed has been swelled in the miniemulsion of the cross-linker and functional monomers together with the template molecules of BPA. After the removal of the seed and the template molecules by extraction, the electron microscopy characterization reveals bowl-like particles with a single hole on the concave surface. The unique single hole hollow structure is determined by the polymerization induced phase separation in the miniemulsion droplets and can be altered by monomer components. The characteristic of MIP is illustrated by the molecular recognition in the rebinding tests, where the particles prepared under the optimal formulation exhibit remarkable kinetics and desirable selectivity towards BPA in the mixed solution of methanol and water (20:80, v/v). The MIP particles with single hole hollow structure would be attractive in environmental and analytic fields for BPA decontamination. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a miniemulsion polymerization strategy to synthesize molecularly imprinted polymer (MIP) submicron particles. Bisphenol A (BPA), an endocrine disrupting chemical, is chosen as the template molecule. The template was dissolved in the mixture of the functional monomer and crosslinking agent. The monomer mixture was emulsified into miniemulsion with the droplet diameter of about 100 nm via sonication. The specific sites were immobilized into polymer particles through the radical polymerization in the droplets. After the extraction of the template, MIP particles were obtained with an average diameter of 138 nm. The formation of recognition sites on the particles was validated by the excellent binding capability towards BPA in the selective and competitive binding experiments. Benefited from the small particle sizes and large surface areas, the MIP particles exhibit accelerated adsorption kinetics. The particles with submicron sizes, excellent BPA recognition accuracy and rebinding efficiency would be attractive in environmental and analytic fields for BPA decontamination. [ABSTRACT FROM AUTHOR]

The design and fabrication of polymer microspheres with structural complexity in Pickering emulsion systems is a pioneering topic in recent years. Herein we report a synthesis of structured and molecularly imprinted multicore rattle-type microspheres through a facile method based on the Pickering emulsion polymerization using silica nanoparticles as the only stabilizer. The void inside the sphere was induced by the polymerization-driven phase separation approach tailoring by the interface interaction. However, the imprinting template of bisphenol A (BPA) is found to serve also as the heterogeneous nuclei, whose superimposition on the polymerization induced phase separation creates the opportunities for the formation of the multicores encapsulated in the shell. A simple adjustment on the composition of the oil phase enabled the evolution of sphere internal structures from single void to multicores. Specifically, the reversibly incorporated BPA on the polymer spheres can be removed by extraction with the molecular information left and immobilized by crosslinking as the imprinted sites. The imprinted spheres can be used to selectively rebind BPA, which was comprehensively evaluated by a batch of rebinding experiments. The rattle-like microspheres recognized BPA molecules from their analogues and effectively removed them from the matrix with accelerated adsorption kinetics, which shows potential applications in the environmental or analytic fields where the removal or separation of BPA as an endocrine-disrupting chemical is in high demand. [ABSTRACT FROM AUTHOR]

The adsorptive materials which have the function of molecular recognition are becoming important as the fast emerging environmental requirements for the analysis and repair of target contaminants present at low concentrations in aqueous matrices. Here, we demonstrate a Pickering emulsion polymerization strategy to build bisphenol A (BPA) imprinted poly(methacrylic acid) microspheres without the traditional organic surfactant. In the synthesis, the only stabilizer is silica particles derived from Stöber process. The molecularly imprinted polymer microspheres were prepared by radical polymerization in the Pickering oil/water emulsion. Both the solid stabilizers and the molecular templates were conveniently removed from the microspheres. The obtained microspheres are of regularly spherical structures and hydrophilic surfaces. The formation of molecularly imprinted sites on the microspheres was validated by the excellent recognition capability toward BPA in the rebinding and competitive binding experiments. [ABSTRACT FROM AUTHOR]