Fast Switching Properties and Ion Diffusion Behavior of Polytriphenylamine Derivative with Pendent Ionic Liquid Unit

Abstract

A novel triphenylamine derivative-linked ionic liquid unit, 1-(6-((4-(bis(4-(thiophen-2-yl)phenyl)amino)benzoyl)oxy)hexyl)-3-methyl-imidazolium tetrafluoroborate (TTPACIL-BF), was designed and synthesized successfully, and its corresponding polymer PTTPACIL-BF was obtained by the electropolymerization method. The highest occupied molecular orbital energy band of TTPACIL-BF is higher and the onset oxidative potential lower compared with that of 6-bromohexyl 4-(bis(4-(thiophen-2-yl)phenyl)amino) benzoate (TTPACBr) without modifying the ionic liquid unit. Both PTTPACIL-BF and PTTPACBr show similar color change and optical contrast under different redox states. However, PTTPACIL-BF presents a faster electrochromic switching time than PTTPACBr owing to the improved ionic conductivity and ion diffusion coefficient with the introduction of a pendent ionic liquid unit. It is more intriguing that PTTPACIL-BF could show electrochromism under different potentials even without supplying any additional electrolyte. The particular behavior further proves that BF ions around imidazole cations at the side chain may participate in balancing the charge of the polymer backbone when redox reaction happens, resulting in faster movement of ions during the doping process. The results imply that introducing an ionic liquid unit to the side chain is an efficient method to improve the switching time of conjugated polymers and would be inspirational for the design and preparation of novel bifunctional electrochromic polymeric electrolytes.

Ionic Liquid‐Based Stimuli‐Responsive Functional Materials

“…Table 4 shows the main ionic liquid structures discussed in this review. Through the chemical functionalization [137] Copyright 2018, American Chemical Society. b) Spectro-electrochemical cell configuration for the analysis of ECDs and the reduction-oxidation mechanism of the new smart PIL.…”

“…The result indicated that the IL‐based electrolytes presented a faster electrochromic switching time than the traditional electrolytes without ILs unit, attributing to the improved ionic conductivity and ion diffusion coefficient with the introduction of ionic liquid segment as shown in Figure a. [ 137 ] The particular behavior further proved that the ion diffusion behavior played an important role in electrochromism and has a significant influence on its performance, especially the switching time. Besides, an all‐in‐one switchable electrochromic device with remarkably fast response time ( t red = 14 s; t ox = 17 s) and good coloration efficiency (76.8 cm 2 C −1 ) has been developed by integrating a viologen unit into the main chain of ILs.…”

“…[136] IL-based electrochromic materials have gradually received more attention and become a promising research field due to their great potential in smart windows and electronic display devices. [137][138][139][140][141] In this context, a novel triphenylamine derivative-linked ionic liquid, 1-(6-((4-(bis(4-(thiophen-2-yl)phenyl) amino)-benzoyl)oxy)hexyl)-3-methyl-imidazolium tetrafluoroborate (TTPAC 6 IL-BF 4 ), has been synthesized and used as a functional electrolyte in smart windows. The result indicated that the IL-based electrolytes presented a faster electrochromic switching time than the traditional electrolytes without ILs unit, attributing to the improved ionic conductivity and ion diffusion coefficient with the introduction of ionic liquid segment as shown in Figure 23a.…”

Recent Advances on Stimuli‐Responsive Smart Materials and their Applications

“…For example, ferrocene, triphenylamine, catenanes, pseudorotaxane, azobenzene, spiropyran, pyridines, diarylethene and phthalocyanines extensively investigated under light at various excitation wavelengths and applied into molecular machines, actuators, switches and electronic applications. [7][8][9][10][11][12] Whereas, tetrathiafulvalenes (TTFs), thiophenes, napthelenediimides (NDIs) and metalpolypyridyl complexes considered eletrochromic materials owing to mixed valence species generation via voltage leads artificial muscles, nanorobots and electronic noses. Likewise, extended diimides, porphyrins, tetrathiazolylthiophene, Schiff bases and borondipyrromethane moieties responded very well with sonication, force, stress/strain, heat and pH results the memory devices, drug-delivery and chemotherapeutic applications.…”

A new green‐to‐transmissive polymer with electroactive poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) as an interface layer for achieving high‐performance electrochromic device

“…Electrochromic (EC) materials as a new functional material have shown broad application prospects in smart windows, displays, and data storage devices . Conjugated polymers (CPs) have been used in EC devices as active layer, because of their fast switching time, high optical contrasts, flexible processability, and easy tunable color . For the realization of EC display devices, it is indispensable to obtain the neutral red, green, and blue (RGB) polymers for meeting the full‐color showing.…”