Controlling self-assembling and color-transition of polydiacetylene/zinc(II) ion/zinc oxide nanocomposites by varying pH: Effects of surface charge and head group dissociation

Abstract

© 2019 The Korean Society of Industrial and Engineering Chemistry Polydiacetylene/zinc(II) ion/zinc oxide (PDA/Zn2+/ZnO) nanocomposite exhibits reversible thermochromism and dual colorimetric response to acid/base. This contribution presents our ongoing development of the PDA/Zn2+/ZnO nanocomposite for sensing applications by controlling ZnO surface charge and dissociation of PDA headgroup via pH adjustment. At pH >10, negative ZnO surface charge and PDA carboxylate headgroup significantly enhance molecular organization during the self-assembling process. An increase of the nanocomposite amount after photopolymerization is observed. Oppositely, pH <6 results in irreversible-thermochromic nanocomposites. Additionally, the nanocomposites prepared at different pH change color at different concentrations of chemical stimuli. Molecular packing, local interactions and PDA conformation are investigated.