Structural-thermochromic relationship of polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites: Effects of PDA side chain length and PVP molecular weight

Reversible thermochromic polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites are prepared by using 6 diacetylene (DA) monomers. The use of relatively low molecular weight (MW) PVP provides the nanocomposites with reversible thermochromism. The shortening of PDA alkyl tail causes the decrease of color-transition temperature, ranging from 75 to 85 °C. The shortening of alkyl segment adjacent to PDA carboxylic head group, however, does not provide the same trend. The nanocomposites constituting PDAs with 8, 6 and 4 methylene units exhibits color-transition at about the same temperature. The increase of PVP MW reduces the color-transition temperature and also affects thermochromic reversibilty of the PDA/PVP nanocomposites.