Tuning the sensitivity of polydiacetylene-based colorimetric sensors to UV light and cationic surfactant by co-assembling with various polymers

Abstract

This study introduces a simple approach for fine-tuning the sensitivity of polydiacetylene(PDA)-based colorimetric sensors to UV light and cationic surfactant. The PDA assemblies were prepared by co-assembling of 10,12-pentacosadiynoic acid (PCDA) monomer and 3 types of water-soluble polymers, including poly(vinylpyrrolidone) (PVP), poly(N-vinyl formamide) (PNVF) and poly(N,N-dimethyl acrylamide) (PDMA). X-ray diffraction reveals the intercalation of these polymers with PDA bilayers. Infrared spectroscopy also observes the variation of local interactions within PDA/polymers assemblies, depending on the structure of polymeric side chain. The incorporation of these polymers strongly affects the color-transition behaviors of PDA upon exposure to UV light and cationic surfactant. The PDA/polymer assemblies show significant improvement in UV light sensitivity. The color transition upon prolonged exposure to UV light can also be controlled. The addition of PVP and PNVF chains provides the sensors that change color at relatively long UV light irradiation time. The use of PDMA, however, causes the opposite result. The same approach is utilized for preparing quantitative-colorimetric sensors of cationic surfactant. The variation of polymeric side chain or molecular weight provides the PDA/polymer assemblies that change color at different concentration of the cationic surfactant.