Versatile route to prepare reversible thermochromic polydiacetylene nanocomposite using low molecular weight poly(vinylpyrrolidone)

Abstract

© 2016 Elsevier B.V. This contribution introduces a simple method to prepare polydiacetylene(PDA)-based materials with reversible thermochromism. The incorporation of low molecular weight poly(vinylpyrrolidone) (PVP10) into the PDA assemblies, prepared from 10,12-pentacosadiynoic acid (PCDA) monomer, enhances inter- and intrachain interactions within the system. The PVP10 is simply added during conventional preparation methods without requiring any other treatments. X-ray diffraction technique reveals the increase of interlamellar distance, which indicates the intercalation of PVP10 chains with the poly(PCDA) layers. The resultant poly(PCDA)/PVP10 nanocomposite exhibits higher color-transition temperature compared to that of the pure poly(PCDA) assemblies. In addition, the blue-to-purple color transition of poly(PCDA)/PVP10 nanocomposite in aqueous solution is fully reversible during 10 consecutive heating/cooling cycles. When the poly(PCDA)/PVP10 nanocomposite is fabricated into thin film, it exhibits two-steps color transition, reversible blue-to-purple at 90 °C and reversible purple-to-red at 150 °C. The complete color reversibility of this system persists up to 200 °C. Raman scattering spectroscopy is utilized to investigate color stability and the change of PDA backbone conformation within the nanocomposite during the color-transition process. We also demonstrate that the preparation conditions such as the PVP10 concentration and incubation time significantly affect the color reversibility of the resultant nanocomposites. Their size and shape are influenced by the PCDA/PVP10 mixing process.