Structurally Colored Thermochromic Gels Derived from Plasmonic Gold Nanoparticles and Cholesteric Hydroxypropyl Cellulose

The integration of functional components into thermochromic photonic crystals has attracted considerable interest due to their potential for developing stimuli-responsive materials with distinctive optical characteristics. In this study, we demonstrate a series of optically tunable thermochromic gels, formed through the coassembly of gold nanoparticles with hydroxypropyl cellulose (HPC) at high concentrations (60-68 wt %), producing vibrant structural colors with enhanced light absorption. These composites not only preserve the chiral self-assembly of HPC in the presence of nanoparticles but also introduce tunable photonic-plasmonic coupling that responds to both temperature and concentration variations. Moreover, by exploiting the chiral light-matter interactions between the gold nanoparticles and the HPC, we observed a pronounced temperature-sensitive plasmonic optical activity, characterized by a strong negative peak on CD spectra, resulting from the chiral photonic modulation of the HPC. This approach for fabricating optically tunable thermochromic materials with engineered photonic-plasmonic coupling opens new avenues for advanced optical applications.