Construction of polydopamine-polyethyleneimine composite coating on the surface of poly (styrene–divinylbenzene) microspheres followed by quaternization for preparation of anion exchangers

As a mussel-inspired material, dopamine (DA) is widely applied for the surface modification of various bulk materials based on its self-polymerization properties. Whereas, polydopamine (PDA) modified poly (styrene–divinylbenzene) (PS-DVB) microsphere is still hard to be quaternized under mild conditions. In this work, polyethyleneimine (PEI) is selected as the comonomer to participate in the crosslinking with PDA to form PDA-PEI composite coating on the surface of PS-DVB microsphere. Then, PS-DVB@PDA-PEI microsphere is further quaternized utilizing PDA-PEI coating as the secondary functionalized platform to prepare anion exchanger. The anion exchanger is characterized by scanning electron microscope, fourier transform infrared spectroscopy, nitrogen adsorption–desorption measurement, X-ray photoelectron spectroscopy, elemental analysis, thermogravimetric analysis. The chromatographic performance is evaluated by separating seven conventional anions, organic weak acids, et. al. The results indicate that PDA-PEI shows higher reactivity than PDA due to the present of abundant amine groups. The introduce of PDA-PEI coating makes PS-DVB microspheres can be quaternized under mild conditions. The strategy presented here is very suitable for the preparation of anion exchangers.