Polyurethane-based Eu(iii) luminescent foam as a sensor for recognizing Cu2+ in water

Abstract

A novel porous polymer material with red emissions composed of a europium silica hybrid and polyurethane foam has been assembled. Its sensing properties in water have been investigated and the fluorescence of the foam was selectively quenched in the presence of Cu²⁺ (detection limit 3.4 μM) compared with other cation ions (Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cr²⁺, Mn²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Pb²⁺ and Ag⁺). The high selectivity and sensitivity were attributed to the strong chelation of Cu²⁺ with nitrogen atoms of the ligand (L) and the photo-induced electron transfer effect. The luminescent polyurethane foam showed a good reusability (more than 10 times). Interestingly, the red emission can be switched “off” and “on” via the addition of copper ions and EDTA, respectively. Additionally, the tensile failure tests proved that higher mechanical strength could be achieved in the silica material reinforced polyurethane foam.