Mesoporous polystyrene-based microspheres with polar functional surface groups synthesized from double emulsion for selective isolation of acetoside

Abstract

In this study, a series of the functionalized mesoporous polystyrene-based microspheres (FMPMs) with different functional comonomers (acrylamide, AM; ethyleneglycol dimethacrylate, EGDMA; hydroxyethyl methacrylate, HEMA) and ratios of styrene (St) to divinylbenzene (DVB) were designed and synthesized by a double emulsion interface polymerization method. Among them, St and DVB existed in the oil phase, forming the skeleton structure of FMPMs. AM, EGDMA or HEMA in the water phase formed functional layers on the inner and outer surfaces of FMPMs. The experimental results indicated that the optimal functional comonomers and the ratio of St to DVB were AM (provided the hydrophilic -CONH₂ groups) and 1:1, respectively. Thus, A-FMPMs-2 exhibited the highest adsorption capacity of 108.95 ± 8.13 mg/g and the selectivity of 5.14 ± 0.17. These results were attributed to the hydrophilic -CONH₂ groups on A-FMPMs-2, and these groups were beneficial to ACT molecules diffusion driven by concentration gradient, improving the adsorption performance. Furthermore, hydrophilic -CONH₂ groups on the inner and outer surfaces of A-FMPMs-2 acted as hydrophilic sites that had a high-affinity interaction with ACT molecules, thus increasing the adsorption selectivity. In addition, A-FMPMs-2 had the highest specific surface area and largest pore volume, resulting in the highest adsorption capacity and adsorption selectivity. Therefore, the development of adsorbents with adjustable pore structure and a large number of hydrophilic sites will provide a new strategy for selective separation of bioactive components from natural products.

Keywords: Acteoside; Double emulsion; Hydrophilic site; Polystyrene porous microspheres; Selective isolation.