Coordination interaction based two-dimensional photonic crystal polyacrylic acid hydrogel material for sensitive and visual detection of uranyl ion in water

Uranyl ion (UO 2 2+ ) is both radiotoxic and chemically toxic, which has harmful effects on the ecological environment and human health. This work presents a novel material called two-dimensional photonic crystal polyacrylic acid hydrogel (2D-PCPAAH), which contains massive carboxyl groups that can bind to UO 2 2+ by strong coordination interaction. UO 2 2+ can be combined with multiple ligand groups, causing the shrinkage of the 2D-PCPAAH which results in a reduction in particle spacing and a color change. Via measuring the Debye diffraction ring diameter using a ruler, the particle spacing can be easily obtained and the UO 2 2+ concentration can be determined.