Preparation and thermochromic behaviors of polydiacetylene/indium or gallium doped zinc oxide nanocomposites

Polydiacetylene (PDA) is one of the well-known thermochromic materials having a high potential in applications such as displays and sensor technology. Many research groups have been working on controlling thermochromic reversibility of PDA-based materials. In this research, the colorimetric response of PDA assembled with indium or gallium doped zinc oxide was studied with various concentrations. Indium or gallium doped zinc oxide was prepared by hydrothermal method. The compositions of 5, 10, and 15% of indium and 5, 12, and 24% gallium, respectively. Undoped zinc oxide and gallium doped zinc oxide exhibited the nanoflowers composed of nanosheets while the indium doped zinc oxide showed the nanorod structure and combined to be nanoflowers. Monomer of PDA composing 10, 12-pentacosadiynoic acid in ethanol was mixed with indium and gallium doped zinc oxide precursor solution at 20% weight. Ultra-violet light source was used to photo-polymerize for five minutes after incubation at low temperature for a prolong cooling. For nanocomposites of poly(PCDA) and undoped and gallium doped zinc oxide, the color of nanocomposite changed from blue to light-purple at above 70°C and the color can be reversible when cooling down to room temperature. However, for nanocomposites of PCDA and indium doped zinc oxide, the color change from blue to light-purple at above 50°C then become red than those in gallium doped PDA nanocomposite. In addition, the color of PCDA nanocomposite with indium doped zinc oxide cannot be reversible back to the original color. (paper)