Preparation And Performances Of Polyaniline/Carbon Nanostrutures Hybrid Electrochromic Materials

Electrochromic materials can change their oxidation and reduction states reversibly in the AC electric field, and exhibit reversible changes of the transmittance, absorbance, and reflection of light and color. Accordingly, they have been widely used in the fields of display, smart windows, anti-glare rear-view mirrors and military camouflage. Conducting polymer has been viewed as one of the promising electrochromic materials, attributing to its fast switching speed, abundant color change, easy preparation, good processability and low cost. But how to improve the reliability of conducting polymer to achieve the large-scale production is the key issue of current study. We focus our research works on the synthesizing and designing of the conducting polymer composites electrochromic materials. The organic-inorganic hybrid approach is utilized to improve the materials properties, and enhance the device performances.In this article, we have synthesized the polyaniline/carbon nanostrusture hybrids through interfacial bonding method. The polyaniline/carbon nanostructure hybrids electrochromic materials with strong interfacial interaction were prepared by connecting the polyaniline with various dimensional carbon nanostructures(carbon nanotubes and graphene) through interfacial covalent bond. Also, the electrochromic devices were assembled. Then, the structure, morphology and the electrochemical properties of electrochromic materials were characterized. The performances of electrochromic devices were tested. Further, the performance enhanced mechanisms of materials were studied.Firstly, the functionalized carbon nanotubes containing aniline group was introduced into the polymerization system of aniline to prepare polyaniline/carbon nanotubes(PANI-SWCNT) hybrids electrochromic materials. The influences of different carbon nanotubes content on the material properties were investigated. The results indicate that PANI-SWCNT have the better properties than the pure polyaniline. And with the addition of carbon nanotubes, the contrast of hybrid materials increase from 0.38 of pure polyaniline to 0.47 of hybrids that contains 0.8 wt.% of carbon nanotubes. At the same time, the responding speed is improved at different extent. Then, the polyaniline/graphene(PANI-rGO) hybrids electrochromic materials have been synthesized also. The results reveal that PANI-rGO has the different electrochromic properties as comparison with PANI-SWCNT. Especially, the responding speed and the contrast don’t show the same trend with the increase of the graphene content, which may relate to the ion transport blocking effect of the sheet structure of the graphene sheet. Finally, the carbon nanotubes and graphene were introduced simultaneously into the polymerization system of aniline to prepare polyaniline/graphene/carbon nanotubes(PANI-rGO-SWCNT) hybrid electrochromic materials. The results show that the PANI-rGO-SWCNT exhibits nearly 27%contrast enhancement comparing with the pure polyaniline, which is also higher than the contrast of polyaniline/carbon nanotubes hybrids or polyaniline/graphene hybrids.The enhancement mechanism of various dimensional carbon nanomaterials to the electrochromic properties of polyaniline were studied by analyzing the cyclic voltammetry(CV) and electrochemical impedance of the hybrid materials. We think that the carbon nanomaterials can affect the electrochromic properties of polyaniline through enhancing the electronic conduction(conduction) process and the ionic transportation(mass transfer) process. One dimensional carbon nanotubes can improve both the conduction and the mass transfer processes, but the two dimensional graphene would have the negative impacts on the mass transfer process with increase of graphene content. Finally, higher conduction and higher mass transfer can be obtained by controlling the content of two kinds of carbon nanomaterials. Also, the electrochromic materials with higher properties can be achieved.