Thermochromism in polydiacetylene-metal oxide nanocomposites

Abstract

Irreversible and reversible chromatic transitions during heating and cooling cycles were investigated in polydiacetylene poly-PCDA (poly-10,12-pentacosadiynoic acid) composites with nanocrystalline zinc oxide (ZnO), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ) and ZnO and ZrO 2 alloys. In contrast to pure poly-PCDA, poly-PCDA composites with nanocrystalline ZnO displayed rapid reversibility on thermal cycling, whereas the corresponding composites with nanocrystalline TiO 2 and ZrO 2 were irreversible, and poly-PCDA composites with thermally prepared ZnO and ZrO 2 alloys displayed slower reversibility. The mechanism of reversible and irreversible thermochromism in these materials was explored using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray absorption fine structure (XAFS) spectroscopy. In pure poly-PCDA, heating leads to an irreversible strain on the polymer backbone to form a red phase, which is not released on cooling. In the presence of ZnO evidence is provided for chelation involving the side chain head groups which can release strain on cooling to rapidly form the blue phase. Chemical interaction coupled with reversible behavior was however observed only when the composites were prepared with ZnO having an average crystallite size of 300 nm and below with a fraction of an amorphous grain boundary phase. Poly-PCDA composites with ZnO/ZrO 2 alloys showing slower thermochromic reversibility can be used both as temperature and elapsed time-temperature sensors.

Hybrid polydiacetylene/magnetite nanoparticles: Sensing for sodium cetyltrimethylammonium bromide and streptavidin

“…The FTIR spectra of the PDAs [Figure (b)] showed lines at 2625 and 2948 cm −1 due to the asymmetric and symmetric stretching vibrations, respectively, of the CH 2 groups of the PDA side chains . The lines at 1465 and 1697 cm −1 were assigned to the CH 2 scissoring vibrations and hydrogen‐bonded carbonyl CO stretching vibrations . As shown in Figure (c), these peaks were observed in the FTIR spectra of the Fe 3 O 4 –PDA hybrid nanoparticles; this contributed to the magnetic nanoparticles being well loaded onto the PDA nanoparticles.…”

Controlling the reversible thermochromism of polydiacetylene/zinc oxide nanocomposites by varying alkyl chain length

“…This PDA-based material exhibited color transition at higher temperature compared to that of the pure PDA and interestingly showed reversible thermochromism. The following work by Patlolla and coworkers also observed similar reversible-thermochromic property of PDA/ZnO nanocomposites, while the nanocomposites with TiO 2 and ZrO 2 nanoparticles exhibited irreversible thermochromism [54]. The size of ZnO particles also affected the thermochromic behaviors of the composites.…”

Thermochromism in Polydiacetylene–ZnO Nanocomposites

“…Previous work performed in this group (Patlolla et al 25 ) on poly-PCDA−metal oxide nanocomposites provided a broad understanding of the changes in chromatic properties of the nanocomposites relative to those of pure PCDA. Here a more detailed investigation is carried out using Raman spectroscopy, DSC, and colorimetry using optical densitometry as a function of temperature on poly-TCDA and poly-TCDA/ZnO nanocomposites, together with an ATR-FTIR study at ambient temperature to extract a molecular level understanding of poly-TCDA/ZnO nanocomposite formation.…”