How heat treatment affects the chromatic response of carbon nanotube - Polydiacetylene composites to electrical stimulus

The science of multi walled carbon nanotube (MWCNT) - polydiacetylene (PDA) composites that can change colour from blue to red under electrical stimulus is relatively new and not deeply explored. We studied the effects of heat treatment on the electrically induced transition in MWCNT-PDA composites. X-ray diffraction revealed that heating at 40°C prior to photo polymerization of diacetylene caused the peak intensities to become remarkably intense, suggesting improved order in the polymer film. From in-situ absorption spectra, it was observed that the critical transition voltage increased significantly for pre-heated samples. Moreover, the absence of drift in the in-situ absorbance spectra of annealed samples suggests that heat treatment reduces the ability of PDA to respond collectively to electrical stimulus. In-situ Raman spectra at the critical transition voltage revealed that pre-heat treatment improves the ability of PDA to restore alignment upon removal of electrical stimulus. Pre-heat treatment is thus thought to improve the electrochromic response of MWCNT-PDA composites.