Synthesis of thermosensitive polymer/mesoporous silica composite and its temperature dependence of anion exchange property

An anion exchanger consisting of amino-functionalized MCM-41 type mesoporous silica coated with temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAM), was synthesized in this study. The structure of this composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and elemental analysis. The XRD pattern showed that the synthesized composite had the ordered hexagonal structure and the interplanar spacing, d100, was around 40 Å. The amount of surface-grafted thermosensitive polymer was estimated to be about 0.8 wt.% by elemental analysis. The adsorption–desorption behavior of methyl orange in this synthesized material depended on the temperature of aqueous solution: at 25 °C, the reversible adsorption–desorption of methyl orange was repeated with changing pH of the solution; at 40 °C, the methyl orange was not adsorbed and desorbed independent of pH of the solution.

The adsorption–desorption behavior in the mesoporous silica coated with PNIPAM depended on the temperature of aqueous solution.Figure optionsDownload high-quality image (60 K)Download as PowerPoint slideResearch highlights
► PNIPAM was immobilized on the outer surface of mesoporous silica.
► Amount of anion exchange depended on the temperature of aqueous solution.
► Adsorption and desorption was repeated with changing pH of the solution at 25 °C.
► Molecule was not adsorbed and desorbed independent of pH of the solution at 40 °C.