Electrochromic Ru-Based Metallo-Supramolecular Polymer with a Layered Inorganic−Organic Hybrid Nanocomposite for Improved Electrochemical Properties

Herein, we report improving the electrochromic (EC) properties of metallo-supramolecular polymers (MSPs) via forming nanocomposite with a layered inorganic-imidazoline covalently bonded hybrid ( LIIm ). Polymer-based nanocomposites exhibit improvements in mechanical, optical, gas barrier properties, etc. Clay minerals and organoclays are beneficial additives in synthesizing nanocomposites. However, only a few investigations of their EC properties have been reported. We have prepared the nanocomposites of Ru(II)-based metallo-supramolecular polymer ( polyRu ) and LIIm by mixing them in various polyRu / LIIm ratios in methanol. Then, the EC properties and structural features of the resulting red nanocomposites ( polyRu – LIIm composites) were analyzed. The polyRu – LIIm composites exhibited strong metal-to-ligand charge transfer (MLCT) absorptions at ∼530 nm with a slight red shift (4–7 nm) than that of pristine polyRu . The MLCT absorptions of polyRu – LIIm composites were more intense than that of polyRu . Spin-coated polyRu – LIIm composite films showed a reversible pair of redox waves at half-wave potentials ( E 1/2 ) of 0.9 V in cyclic voltammetry (CV) curves and reversible EC changes between red and pale green caused by the redox of Ru(II/III) upon applied potential. The E 1/2 and peak currents do not drastically change compared to those of polyRu . Furthermore, the composite thin films exhibited coloration efficiencies (CE) of 640–810 cm 2 /C higher than the 597 cm 2 /C of polyRu . The high optical contrasts (Δ T ) of >70% and fast switching times were maintained. Scanning electron microscopy (SEM)–energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses revealed the characteristic structural features of polyRu – LIIm composites where polyRu -coated LIIm forms agglomerate (200 nm–10 μm), which varied with the polyRu / LIIm ratios. Furthermore, the EC memory times were improved to 26 min for one of the polyRu – LIIm composites from 170 s of polyRu .