Thermochromism in Polydiacetylene–ZnO Nanocomposites

Abstract

Room temperature attentuated total reflection (ATR)-Fourier transform infrared (FTIR), temperature-dependent Raman, colorimetric (using optical densitometry), and differential scanning calorimetry (DSC) are used to provide a qualitative mechanism of the thermochromic reversibility introduced by composite formation of poly-10,12-tricosadiynoic acid (poly-TCDA) with ZnO in the particle size range below 100 nm. The results indicate that in pure poly-TCDA, heating above the chromatic blue to red transition temperature leads to an irreversible stress on the polymer backbone due to break up of hydrogen bonding on the side chain head groups to form an irreversible red phase. By contrast, poly-TCDA composites with nanosize ZnO at concentrations above 5 wt % display rapid chromatic reversibility. Reversibility is only partial for composites with 5 wt % ZnO, and interestingly for composites only of this composition the Raman data indicate a broad scattering band which can be assigned to the irreversible formation of an amorphous poly-TCDA/5 wt % ZnO phase network. The appearance of a new line at 1540 cm −1 in the ATR-FTIR spectra of poly-TCDA/ZnO composites is indicative of chelation between head groups on neighboring side chains and ZnO, which facilitates the release of stress on cooling from the red phase to rapidly form the blue phase. Moreover, the colorimetric data show an increase in chromatic transition temperature with increase of the amount of ZnO from 5 to 15 wt % in poly-TCDA. The potential of these nanocomposites as thermochromic temperature sensors is also considered.

The effect of 10,12-pentacosadiynoic acid on the morphology and characteristics of electrospun PDA/PU nanofibers

“…The absorption spectra of PDA-containing PU nanofibers show that the spectra at 3300 cm −1 and 2920 cm −1 due to the PDA were overlapped on PU absorption spectrum (Kim and Lee 2017;Barikani et al 2015;Da Silva et al 2011;Paul et al 2013;Wu et al 2013). The peak of the spectrum, which did not exist in pure PU nanofibers, appears in the PDA/PU nanofiber, which means that the PDA was uniformly dispersed in the PU (Gregorio and Cestari 1994;.…”

Study of Polydiacetylene-Poly (Ethylene Oxide) Electrospun Fibers Used as Biosensors

“…The PDAs usually have absorption at 650 nm, exhibiting a blue color [ 7 ]. When the blue phase PDAs are exposed to external stimuli such as chemical or mechanical stress, the absorption is switched to 550 nm and the color of PDAs becomes red [ 7 , 9 ]. The blue-to-red transformation is visible to the naked eye, which makes PDAs attractive materials for biosensor applications.…”

Multicolor Reversible Thermochromic Properties of Gallic Acid-Cored Polydiacetylenes Appended with Poly(alkyl aryl ether) Dendrons

“…Temperature‐dependent in situ IR spectral analyses were performed up to 250 °C, so as to assess the nature of the alkyl chain conformations, intermolecular hydrogen bonding interactions and the dendron segment in the polymer films of 1 and 2. In thin film of polymer of 1, CH 2 symmetric and asymmetric stretching vibrations at 2919 and 2850 cm −1 underwent a gradual decrease in intensity and shifted to 2926 and 2855 cm −1 , respectively, upon heating the films gradually to 250 °C (Figure ). Similarly, at 1466 and 1424 cm −1 , CH 2 scissoring vibrations underwent shifts to 1455 and 1420 cm −1 , respectively.…”