Temperature-swing microfluidic separation of uranyl ions using thermoresponsive copolymer brushes

This paper reports a novel temperature-swing microfluidic separation method. The selective adsorption-desorption of uranyl (UO₂ ²⁺) ions could be realized by swelling-shrinking of a thermoresponsive copolymer brush, which was constructed with poly(N-isopropylacrylamide) (NIPAAm) and vinylpyrrolidone (VP) ligand, onto a microchannel surface. We clarified that the hydrophilic-hydrophobic transition temperature of the copolymer brush was about 35 °C and that the selectively for UO₂ ²⁺ ions was 92%.