WO3 Nanocomposite Films via

Article pubs.acs.org/JPCC

Electrochromic Poly(DNTD)/WO3 Nanocomposite Films via Electorpolymerization Huige Wei,† Xingru Yan,† Yunfeng Li,†,‡ Hongbo Gu,† Shijie Wu,§ Keqiang Ding,∥ Suying Wei,*,‡ and Zhanhu Guo†,* †

Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710, United States ‡ Department of Chemistry and Biochemistry, Lamar University, Beaumont, Texas 77710, United States § Agilent Technologies, Inc., Chandler, Arizona 85226, United States ∥ College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, Hebei 050016, People's Republic of China S Supporting Information *

ABSTRACT: Poly(DNTD,N,N′-di[p-phenylamino(phenyl)]-1,4,5,8-naphthalene tetracarboxylic diimide) and its nanocomposite film incorporated with WO3 nanoparticles was prepared by a facile electropolymerization method on an indium in oxide (ITO) coated glass slide from the DNTD monomer and WO3 nanoparticles suspended methylene chloride solution. The morphology and microstructure of the nanocomposite film were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM image shows that the WO3 nanoparticles are uniformly embedded in the polymeric matrix. The nanocomposite film also displays smooth topography with evenly sized and uniformly distributed nanoparticles under high resolution AFM observations. An air-stable electrochromical window was assembled and obtained by a homemade electrochemical cell to study the electrochromism and stability of the nanocomposite film. The composite film exhibits multiple colors at both the cathodic and anodic potentials, i.e., light blue at −1.4 V, orange red at −0.8 V, colorless at 0 V, orange green at 0.8 V, light blue at 1.0 V, and deep blue at 1.2 or 1.4 V vs Ag/AgCl in propylene carbonate containing 1.0 M LiClO4 electrolyte. The UV−visible incorporated electrochemical spectroscopy coupled with amperometry were also employed to study the composite film under different potentials in the range of −1.4 to 1.4 V vs Ag/AgCl. The composite film also shows stable electrochromism even after 100 scans. The thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) analysis suggest the hydrogen bonding formed between the monomers and WO3 particles, resulting in an increased initial oxidation potential for the monomer during the poly(DNTD)/WO3 nanocomposite film formation. with M+ = H+, Li+, Na+ or K+, and e− denoting electrons, and x representing the number of cations exchanged at the WO3 electrode. However, single color changes between blue and transparent limits the application of WO3 in electrochromic devices. Meanwhile, the electrochromic properties of the conducting polymers have gained much popularity both from the academia and industry owing to their easy processability, rapid response time, high optical contrast, and the ability to modify their structures to create multicolor electrochromes.18−20 The electrochrmomism in conjugated polymers occurs through changes in the π-electronic character accompanied by reversible insertion and extraction of ions through the polymer films upon electrochemical oxidation and reduction.21 Polypyrroles (PPy), 2 2 poly(p-phenylenebenzobisthiazole), 2 3 poly-

1. INTRODUCTION Electrochromism, as a reversible optical change, occurs upon the reduction (gain of electrons) or oxidation (loss of electrons), on the passage of an electrical current after applying an appropriate potential in the material.1,2 Electrochromic (EC) materials can be classified into three groups: inorganic materials (transition metal oxides),3,4 organic small molecules,5−7 and conjugated conducting polymers.8−11 Among those inorganic EC materials, WO3 has many advantages, including genuine color switching, good chemical stability, and strong adherence to the substrate.12−15 WO3 is perceived as a prospective candidate for energy-saving devices such as smart windows for usage in cars and buildings. It is generally accepted that the injection and extraction of electrons and alkaline metal cations plays a key role in yielding the electrochromic effect, which can be illustrated as below:4,16,17

Received: April 29, 2012 Revised: July 7, 2012 Published: July 9, 2012

WO3 + x(M+ + e−) → MxW(l − x) VIWx V O3 transparent

blue © 2012 American Chemical Society

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dx.doi.org/10.1021/jp304127z | J. Phys. Chem. C 2012, 116, 16286−16293

The Journal of Physical Chemistry C

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(thiophene), and their derivatives19,24 and composites25,26 have been reported. N,N′-di[p-phenylamino(phenyl)]-1,4,5,8-naphthalene tetracarboxylic diimide (DNTD), a bis(diphenylamine)naphthalene diimide, belongs to the class of conjugated conducting polymers with a chemical structural motif of R−X−R, where R represents the diphenylamine (DPA) group and X represents naphthalene tetracarboxylic diimide (NTCDI) group as the electroactive center. Materials made from this monomer exhibit low dielectric, high thermal/ oxidative stability,27 and increased bulk conductivity through πstacking interactions.28 The electrochemical and optical properties of the pure polymer thin films have been widely investigated and well elucidated by cyclic voltammetry, UV− vis spectroelectrochemistry,29 and electrochemical quartz crystal microbalance (EQCM),30 and hybrid electrochromic fluorescent poly(DNTD)/CdSe@ZnS composite films have been prepared successfully.31 Multiple-color EC materials with switching at different potentials by combining both EC poly(DNTD) with EC WO3 as electrochromic applications have not been reported. In this work, the poly(DNTD)/WO3 nanocomposite thin films were prepared by an oxidative electropolymerization. The morphology and electrochemical properties of the nanocomposite thin film were analyzed by SEM, AFM, cyclic voltammetry (CV), and in situ spectroelectrochemistry, an analytical method combining the electrochemical and visible spectra. Furthermore, the interactions of the monomer and WO3 nanoparticles were investigated using FT-IR and thermogravimetric analysis (TGA) method, which were used together with CV to illustrate the poly(DNTD)/WO 3 nanocomposite thin film formation mechanism.

ethanol and activated by a mixed aqueous solution containing 1 mL ammonium hydroxide (28.86 wt %, Fisher), 1 mL hydrogen peroxide (30.0 wt %, Fisher), and 5 mL deionized water before the usage. 2.2. Electrochemical Synthesis of Pure Polymer and Nanocomposite Thin Films. Pure poly(DNTD) and poly(DNTD)/WO3 nanocomposite thin films were prepared by oxidative electropolymerization from CH2Cl2 solutions containing the monomer (1 mM), supporting electrolyte TBAPF6 (0.1 M) in the absence or presence of WO3 nanoparticles (0.01 M) with multiple cycles of cyclic voltammetry (CV) performed on an electrochemical working station VersaSTAT 4 potentiostat (Princeton Applied Research). In order to reduce the aggregation of WO3 nanoparticles in the solution, magnetic stirring was applied during the electropolymerization. A classical three-eletrode electrochemical cell consisting of a working, reference, and counter electrodes was used. Ag/AgCl electrode saturated with KCl served as the reference electrode and a platinum (Pt) wire as the counter electrode. An ITO coated glass slide was used as the working electrode for optical and electrochemical characterizations. A long path length, homemade spectroelectrochemical cell with Teflon cell body with front and rear windows clapped with two steel plates was used when the ITO glass slide served as the working electrode. The procedures for the electrochemical polymerization of the monomers have been described elsewhere.28 To obtain significant color change, the electrochemical polymerization was performed 15 cycles scanned back and forth from 0.0 to 1.8 V vs Ag/AgCl at a scan rate of 200 mV/s with 1 mM monomer in CH2Cl2 instead of 0.5 mM monomer with 10 cycles of cyclic voltammetry in our previous work.31 All of the potentials given in this work were values vs Ag/AgCl, and all of the experiments were performed at room temperature. 2.3. Characterizations. The morphologies of the films grown on the ITO glass slides were observed by a scanning electron microscope (Hitachi S-3400 scanning electron microscopy), and further characterized by atomic force microscopy (AFM, Agilent 5600 AFM system with multipurpose 90 μm scanner). Imaging was done in acoustic ac mode (AAC) using a silicon tip with a force constant of 2.8 N/ m and a resonance frequency of 70 kHz. The Fourier transform infrared (FT-IR) spectra of the pure polymer and nanocomposite films were obtained on a Bruker Inc. Vector 22 (coupled with an ATR accessory) in the range of 500 to 4000 cm−1 at a resolution of 4 cm−1. The electrochemical properties of pure polymer and composite thin film onto ITO were investigated by CV scanned from −1.2 to 1.5 V vs Ag/AgCl. The three-electrode cell was bubbled with ultrahigh purity nitrogen (Airgas) for at least 15 min before the test. The spectroelectrochemical experiments were performed by coupling a homemade spectroelectrochemical cell and Varian Cary 50 Version 3 UV−vis spectrometer in PC electrolyte containing 1.0 M LiClO4. The three-electrode cell was bubbled with ultrahigh purity nitrogen (Airgas) when the potential was sweeped at negative vs Ag/AgCl. Each spectrum was taken when the electrochemical cell current decayed to zero and the data were obtained by the mode of medium in Varian Cary WinUV Bio software. At each applied potential, a minimum of three spectra were taken to verify the consistency. To gain further understanding of the interactions between monomer DNTD and WO3 particles, DATD modified WO3 and pristine WO3 particles are prepared and characterized using

2. EXPERIMENTAL SECTION 2.1. Materials. Methylene chloride (CH2Cl2, 99.9%) and tetrabutylammonium hexafluorophospate (TBAPF6, 98%) were purchased from Alfar-Aesar. The WO3 nanopowers with an average diameter of 30 nm were obtained from Nanostructured & Amorphous Materials, Inc. Lithium perchlorate (LiClO4) and propylene carbonate (PC) were from Sigma-Aldrich. All of the chemcials were used as received without any treatment. The synthesis of monomer DNTD is described in the literature.28 Briefly, N-Phenyl-1,4-phenylenediamine (1.20 g, Alfar-Aesar, 98%) was dissolved in 45 mL N,N-dimethylformamide (DMF, Alfar-Aesar, 99%) in a flask (150 mL) and heated to 90 °C. Then 1,4,5,8-naphthalene tetracarboxylic dianhydride (0.60 g, Alfar-Aesar, 98%) and zinc acetate (75 mg, Zn(Ac)2, anhydrous, Alfar-Aesar, 99%) were added into the above solution portionwise over 10 min. The temperature of the mixture solution was raised to 130 °C and held constant for 19 h in the nitrogen environment. The product was precipitated out with the diethyl ether and filtered. The solid product was rinsed with diethyl ether until the product became sky blue. Scheme 1 shows the chemical structure of DNTD. The microscope glass slides and indium tin oxide (ITO) coated glass slides were purchased from Fisher and Delta technologies, Limited, respectively. ITO coated glass slides were degreased in Scheme 1. Chemical Structure of the Monomer DNTD

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Figure 1. Films growth of (a) pure DNTD and (b) DNTD/WO3 onto ITO in CH2Cl2 solution containing 0.1 M TBAPF6 and 1.0 mM DNTD monomer at room temperature. Scan rate is 200 mV/s.

WO3 solution caused by WO3 particles into the monomer solution. 3.2. FT-IR Analysis of the Poly(DNTD) and Poly(DNTD)/WO3 Nanocomposite Films. Figure 2 shows the

thermo-gravimetric analysis (TGA, TA Instruments Q-500) and FT-IR methods. Modified WO3 particles were obtained from the solution containing the monomer DNTD and WO3 particles, and were rinsed several times with excessive CH2Cl2 to remove the monomers physically adsorbed on the surface. The TGA was performed at a temperature range of 25 to 800 °C with an air flow rate of 60 mL/min and a heating rate of 20 °C/min to quantify the content of the monomer DNTD adsorbed on the WO3 particles. The FT-IR characterizations of the modified WO3 and pristine WO3 nanoparticles were carried out at the same conditions as those for pure polymer and nanocomposite films.

3. RESULTS AND DISCUSSIONS 3.1. Synthesis of Poly(DNTD) and Poly(DNTD)/WO3 Nanocomposite Films. Figure 1(a,b) shows the cyclic voltamogram of DNTD (a) and DNTD/WO3 (b) growth on ITO. The current increased with increasing cycles, reflecting the growth of pure polymer and nanocomposite thin films. The cyclic voltamogram of DNTD obtained on the ITO, Figure 1(a), is quite different from the CVs usually obtained by electropolymerization of DNTD on platinum electrodes, which commonly exhibited well-defined redox peaks corresponding to a series of redox transitions: oxidation of diphenylbenzidene (DPB) unit into its radical cation DPB+, followed by the oxidation of radical cation DPB+ into dication (DPB2+).31,32 Besides, the monomer was oxidized at a more positive potential, 1.56 V, compared to 1.34 V for the monomer electrodeposited onto platinum electrodes. A similar phenomenon has been observed for the electropolymerization of other monomers such as aniline.33 The different behaviors might be attributed to the conductivity difference of the substrates that renders the electropolymerization of the monomers easier on Pt than that on the indium tin oxide substrates.34−36 For the electropolymerization of DNTD/WO3, Figure 1(b), the electrochemical responses of poly(DNTD)/WO3 solution is similar to that for the pure polymer film preparation, except that the oxidation of the monomer during the first positive scan occurred at a more positive potential, around 1.65 V, compared to 1.56 V for the electropolymerization of pure DNTD, indicating the possible interactions between the monomer and WO3 particles. Slightly lowered peak currents were also observed, suggesting a lowed polymerization rate,37 which can be explained by the slightly increased resistance of the DNTD/

Figure 2. FT-IR spectra of (a) pristine WO3 nanoparticles, (b) the monomer DNTD, and thin films of (c) ploy(DNTD) and (d) ploy(DNTD)/WO3 grown on the ITO coated glass.

FT-IR spectra of pristine WO3, monomer DNTD, poly(DNTD), and poly(DNTD)/WO3 nanocomposite thin films. For WO3, Figure 2(a), the band typical of W−O appears in the range of 600−1000 cm−138−40 with a maximum at 609 cm−1, characteristic of a disordered tungsten−oxygen framework.9,41 For the monomer DNTD, Figure 2(b), the bands at 1518 and 1405 cm−1 were assigned to the semicircle stretch modes of the para-substituted benzene ring, and 1495 and 1444 cm−1 bands were assigned to the semicircle stretch modes of the monosubstituted benzene ring.28 The band at 1660 cm−1 corresponded to the asymmetric stretch mode of diimide. These peaks are present in the FT-IR spectra of poly(DNTD) and poly(DNTD)/WO3 thin films. What’s more, the peak characteristics of W−O−W are also found in the poly(DNTD)/WO3 nanocomposite thin film and are shifted to a higher wavenumber of 613 cm−1, even though the signal is not very strong due to the low content (13.5 wt %) of the WO3 particles in the polymer matrix, as shown in the EDAX spectrum, see the Supporting Information. However, the redshift of the N−H stretch vibration at 3393 cm−1, Figure 2(c), to 3366 cm−1, Figure 2(d), is also observed in the poly(DNTD)/ 16288



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Figure 3. SEM images of thin films of (a) pure poly (DNTD) and (b) ploy(DNTD)/WO3 nanocomposites grown onto ITO coated glass.

Figure 4. AFM images of (a) poly(DNTD) and (b) poly(DNTD)/WO3 nanocomposite film grown onto ITO coated glass.

thickness of the film on the right part. The thickness of the films is measured to be 88.8 and 83.1 nm for pure poly(DNTD) and poly(DNTD)/WO3, respectively. The small difference in the thickness of the pure poly(DNTD) and its nanocomposite films is consistent with the slightly lower current in the electropolymerization process. Quite different from that obtained at low concentration and fewer numbers of CVs, poly(DNTD) displays porous structures under high resolution. The difference might be explained that at higher concentrations of the monomer, the film grows quickly and yields less orderly structure of higher thickness with larger numbers of CVs.42 Interestingly, poly(DNTD)/WO3 nanocomposite film shows evenly sized and uniformly distributed nanoparticles under high resolution. It thus can be inferred that the interaction between the monomer and WO3 particles plays a part in the composite film preparation process. 3.4. Electrochemical Properties. After the electropolymerization, the electrode with a thin film on ITO was rinsed with fresh CH2Cl2 and was then placed in a degassed CH2Cl2 solution containing only electrolyte, and was cycled again. Figure 5 shows the cyclic voltammograms of thin films of poly(DNTD) and poly(DNTD)/WO3 nanocomposites. Again, pure poly(DNTD) thin film on the ITO exhibits different oxidation/reduction behaviors from those obtained on Pt electrode. Only one oxidation peak at 0.26 V appears and a corresponding reduction peak at 0.27 V occurs at the negative

WO3 nanocomposite thin film. The FT-IR spectrum analysis shows that the poly(DNTD)/WO3 nanocomposite thin film has been successfully prepared by the electropolymerization method. The blue shift of the W−O−W and the red-shift of the N−H, combined with the oxidation potential change indicate the strong interaction between WO3 nanoparticles and the diphenylamine group in the polymer structure. 3.3. Morphology. The morphological characterization is the most important and direct way to evaluate the degree of nanofiller dispersion state in the hosting polymer matrix. SEM was employed to investigate the morphologies of pure poly(DNTD) and poly(DNTD)/WO3 nanocomposite films fabricated on the ITO coated glass. Figure 3 shows the morphology of pure poly(DNTD) and poly(DNTD)/WO3 nanocomposite films. For the pure poly(DNTD) film, Figure 3(a), a uniform smooth film surface is observed. For the poly(DNTD)/WO3 nanocomposite film, Figure 3(b), a composite film with WO3 particles fairly uniformly dispersed in the polymer domain is observed. The right part is the enlargement of the frame in Figure 3(b). WO3 particles can be clearly observed to be embedded in the polymer matrix in the poly(DNTD)/WO3 nanocomposite film. To further investigate the microstructure of the polymer films prepared, AFM measurements were employed. Figure 4 shows the AFM surface topography of pure poly(DNTD) and poly(DNTD)/ WO3 nanocomposite films and large scans revealing the 16289



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accompanied with spectral changes in the UV−vis and IR regions.44−46 Figure 7(a,b) is the in situ spectroelectrochemistry of the poly(DNTD) thin film (a) and poly(DNTD)/WO3 nanocompoiste thin film (b) in propylene carbonate with 1 M LiClO4 upon different potentials, and Figure 8 shows the corresponding color of the films. For poly(DNTD), the spectrum of the charge neutralized film was the same as that in the solvent of CH2Cl2 and shows no absorbance in visible region (400−800 nm).32 The color of the polymer thin film is colorless at 0 V, Figure 8(a). This charge neutralized state was maintained until 0.6 V, and no color change appeared. When the potential was switched to 0.8 V, one peak at about 460 nm which is associated with the formation of radical cation DPB+ was observed, and the corresponding color of this state was orange-yellow. At higher potential, i.e., at 1.0 V, the radical cation DPB+ began to be further oxidized into dication DPB2+, and another peak at 613 nm appeared, and the color changed into light blue. When the potential was further increased to 1.2 V, the bands at 460 nm disappeared while the intensity at 613 nm increased. The reason for that spectral change is probably that most of DPB+ cations were oxidized into DPB2+ at 1.2 V, which could be verified by the almost saturated intensity at 613 nm when further increasing the potential to 1.4 V. At the same time, the color of the film maintains deep blue. When switched to a negative potential, the polymer thin film turned to a colorless state. The film changed into light red at −0.6 V, with a not well-defined peak at 480 nm observed, and the peak became more remarkable at more negative potentials while new bands at 541, 610, and 780 nm appeared. These bands are responsible for the diimide dianions generated in the polymer.32 Accordingly, the film remained light red until −1.4 V, with only slight change in the intensity. For the poly(DNTD)/WO3 nanocomposite thin film, the film shows similar response at positive potentials, as shown in Figure 8 (b). However, at negative potentials, WO3 nanoparticles begin to play a part in the electrochromism. Apart from those characteristic bands of pure poly(DNTD), a new band at 410 nm begins to appear, which is attributed to the LixWO3 formed by the intercalation of Li+ into WO3 with x = 0.25.9 The blue coloration is derived from the cathodically coloring WO3 nanoparticle electrochromism.9,47,48 The film turned to light blue, which is owing to the limited WO3 in the domain of poly(DNTD), as the EDX result shows the W is only about 1% (molar ratio), see Supporting Information.

Figure 5. Cyclic voltammograms of thin films of (a) pure poly(DNTD) and (b) poly(DNTD)/WO3 nanocomposites in 0.1 M TBAPF6 CH2Cl2 DNTD-free solution with a scan rate of 200 mV/s.

sweep. As the shape of the cyclic voltammogram is very sensitive to the morphology of the film,43 therefore it is reasonable to obtain different cyclic voltammograms with different morphologies based on the information provided by AFM. For the poly(DNTD)/WO3 nanocomposite film, the oxidation potential is the same as that of pure polymer, but the films were reduced at 0.34 V in the negative sweep. The widened bandgap of the composite film given by electrochemical method, Eg,EC,(Eg,EC = Eox − Ered) may be induced by the less planar and conjugation of the polymer chains, which was also observed in the poly(DNTD)/CdSe@ZnS nanocomposite films.31 3.4. Spectroelectrochemistry of Poly(DNTD) and Poly(DNTD)/WO3 Nanocomposite Films. Figure 6 shows the oxidation current of poly(DNTD) and poly(DNTD)/WO3 nanocomposite thin films at different applied potentials. For both films, at positive potentials, the current first decreases with increasing the potential until 0.8 V, and then increases with the increase of the potential, indicating the oxidation of the films. At negative potentials, the films are reduced, and the current increases with the increase of the potential. In situ spectroelectrochemical techniques, combining electrochemical and spectroscopic methods, are powerful tools for characterizing the conductive polymers as the redox processes (p- and n-doping) in the conjugated polymers are always

Figure 6. The oxidation current change of thin films of (a) pure poly(DNTD) and (b) poly(DNTD)/WO3 under applied potentials ranging from −1.4 to +1.4 V in propylene carbonate solution containing 1 M LiClO4 as the eletrolyte. 16290



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Figure 7. Transmittance spectra change of thin films of (a) poly(DNTD) and (b) poly(DNTD)/WO3 under applied potentials ranging from −1.4 to +1.4 V in propylene carbonate containing 1 M LiClO4 as the eletrolyte.

DNTD. The result of TGA, Figure 9(a), shows that almost no thermal loss is observed in the pristine WO3 nanoparticles (a maximum thermal loss of 0.56 wt % at 510 °C). At temperatures higher than 510 °C, the pristine WO3 began to gain weight, which might be attributed to the oxidation of superstoichiometric tungsten in the air atmosphere.49 The thermal decomposition of the monomer DNTD begins at 450 °C, and can be fully decomposed until 700 °C. The modified WO3 nanoparticles have the features of both of the pristine WO3 and DNTD, and a maximum thermal loss of 2.3 wt % is observed at 570 °C (0.5 wt % for pristine WO3). Therefore, the content DNTD monomers absorbed onto WO3 is calculated to be 1.8 wt %. In the FTIR spectra, Figure 9(b), a well-defined peak at 609 cm−1 responsible for the framework stretching mode of WO3 can be observed. Compared to that of the pristine WO3 nanoparticles, the peak at 609 cm−1 was shifted to a higher wavenumber, 630 cm−1, and the peak became widened. No significant shift was observed for the peak at 800 cm−1. From the structure of the monomer and WO3, it can be concluded that the hydrogen bonding between W−O with N−H bond of the diphenylamine exists, as shown in Scheme 2. Scheme 2 shows the pure poly(DNTD) and its nanocomposite formation mechanisms. The hydrogen bonding formed is responsible for the more positive oxidation potential of the monomers in the electropolymerization process and widened energy gap of the

Figure 8. Color change of (a) poly(DNTD) and (b) poly(DNTD)/ WO3 composite thin films upon different potentials.

Figure 9(a,b) shows the TGA curve and FT-IR spectra of the pristine WO3, DNTD modified WO3 particles, and monomer

Figure 9. (a) TGA curves of the monomer DNTD, pristine WO3 (right axis), and modified WO3 (left axis), and (b) FT-IR spectra of pristine WO3 and modified WO3. 16291



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Scheme 2. (a) Electropolymerization Mechanism of Films of Pure Poly(DNTD) and (b) Poly(DNTD)/WO3

nanocomposite film as observed in the CV. Similar phenomena have been observed for the nanocomposites of the diaminopyrimidine functionalized poly(3-hexylthiophene) and thymine-capped CdSe nanocrystals as a result of the formation of hydrogen bonding between the polymer and the nanocrystals.50

nanocomposite film promises great potential applications for electrochromic windows.

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ASSOCIATED CONTENT

S Supporting Information *

The EDX spectrum of the poly (DNTD)/WO3 nanocomposite film on ITO coated glass. This material is available free of charge via the Internet at http://pubs.acs.org.

4. CONCLUSIONS Poly(DNTD)/WO3 nanocomposite thin film has been successfully prepared, by oxidative electropolymerization from the solution containing the monomer DNTD and WO3 nanoparticles in CH2Cl2, and electrochemically and spectroelectrochemically characterized. WO3 nanoparticles are observed to be fairly uniformly dispersed in the polymer matrix. The hydrogen bonds formed between the polymer and WO3 nanoparticles exist in the hybrid films. The spectroelectrochemistry (SEC) properties of the film grown on ITO coated glass slide show varied absorption bands characteristic of both the polymer and WO3 nanoparticles when subjected to different potentials, and the hybrid film is multicolored at positive and negative potentials. The poly(DNTD)/WO3

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (Z. G.); suying.wei@lamar. edu (S. W.). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This project is supported by the National Science FoundationNanoscale Interdisciplinary Research Team and Materials Processing and Manufacturing (CMMI 10-30755) managed by Dr. Mary Toney. 16292



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(41) Taylor, T. A.; Patterson, H. H. Appl. Spectrosc. 1994, 48, 674− 677. (42) Painter, P. C.; Coleman, M. M. Fundamentals of Polymer Science, Technomic: Lancaster, PA, 1997. (43) Rougier, A.; Striebel, K.; Wen, S.; Cairns, E. J. Am. Chem. Soc. 1998, 145, 2975−2980. (44) Gale, R. J. Spectroelectrochemistry: Theory and Practice; Springer: New York, 1988. (45) Zoski, C. G. Handbook of Electrochemistry; Elsevier Science: New York, 2007. (46) Wise, D. L. Electrical and Optical Polymer Systems; CRC Press: Boca Raton, FL, 1998. (47) Granqvist, C. G. Sol. Energy Mater. Sol. Cells 2008, 92, 203−208. (48) Oi, T. Annu. Rev. Mater. Sci. 1986, 16, 185−201. (49) Seguin, L.; Figlarz, M.; Pannetier, J. Solid State Ionics 1993, 63, 437−441. (50) De Girolamo, J.; Reiss, P.; Zagorska, M.; De Bettignies, R.; Bailly, S.; Mevellec, J. Y.; Lefrant, S.; Travers, J. P.; Pron, A. Phys. Chem. Chem. Phys. 2008, 10, 4027−4035.

REFERENCES

(1) Rosseinsky, D. R.; Mortimer, R. J. Adv. Mater. 2001, 13, 783− 793. (2) Granqvist, C. G. Sol. Energy Mater. Sol. Cell. 2000, 60, 201−262. (3) Gillaspie, D. T.; Tenent, R. C.; Dillon, A. C. J. Mater. Chem. 2010, 20, 9585−9592. (4) Granqvist, C. G. Electrochim. Acta 1999, 44, 3005−3015. (5) Choi, S. Y.; Mamak, M.; Coombs, N.; Chopra, N.; Ozin, G. A. Nano Lett. 2004, 4, 1231−1235. (6) Mortimer, R. J.; Dyer, A. L.; Reynolds, J. R. Displays 2006, 27, 2− 18. (7) Mortimer, R. J. Electrochim. Acta 1999, 44, 2971−2981. (8) Monk, P. M. S.; Mortimer, R. J.; Rosseinsky, D. R.; Ltd, M. Electrochromism: Fundamentals and Applications; VCH: Weinheim, 1995. (9) Granqvist, C. G. Handbook of Inorganic Electrochromic Materials; Elsevier Science: New York, 1995. (10) Ö zkut, M. I.̇ ; Atak, S.; Ö nal, A. M.; Cihaner, A. J. Mater. Chem. 2011, 21, 5268−5272. (11) Beaujuge, P. M.; Reynolds, J. R. Chem. Rev. 2010, 110, 268−320. (12) Balaji, S.; Djaoued, Y.; Albert, A. S.; Brüning, R. N.; Beaudoin; Robichaud, J. J. Mater. Chem. 2011, 21, 3940−3948. (13) Lee, S. H.; Deshpande, R.; Parilla, P. A.; Jones, K. M.; To, B.; Mahan, A. H.; Dillon, A. C. Adv. Mater. 2006, 18, 763−766. (14) Zhang, J.; Wang, X.; Xia, X.; Gu, C.; Zhao, Z.; Tu, J. Electrochim. Acta 2010, 55, 6953−6958. (15) Wang, J.; Khoo, E.; Lee, P. S.; Ma, J. J. Phys. Chem. C. 2008, 112, 14306−14312. (16) Rowley, N. M.; Mortimer, R. J. Sci. Prog. 2002, 85, 243−262. (17) Granqvist, C. G. Sol. Energy Mater. Sol. Cells 2000, 60, 201−262. (18) Mortimer, R. J. Chem. Soc. Rev. 1997, 26, 147−156. (19) Dyer, A. L.; Craig, M. R.; Babiarz, J. E.; Kiyak, K.; Reynolds, J. R. Macromoles 2010, 43, 4460−4467. (20) Mortimer, R. J. Annu. Rev. Mater. Sci. 2011, 41, 241−268. (21) Gunbas, G.; Toppare, L. Chem. Commun. 2011, 48, 1083−1101. (22) Ak, M.; Gacal, B.; Kiskan, B.; Yagci, Y.; Toppare, L. Polymer 2008, 49, 2202−2210. (23) Zhu, J.; Wei, S.; Alexander, M. J.; Dang, T. D.; Ho, T.; Guo, Z. Adv. Funct. Mater 2010, 18, 3076−3084. (24) Cho, S. I.; Kwon, W. J.; Choi, S. J.; Kim, P.; Park, S. A.; Kim, J.; Son, S.; Xiao, J. R.; Kim, S. H.; Lee, S. B. Adv. Mater. 2005, 17, 171− 175. (25) Masaharu Nakayama, Y. K.; Kazushi, S. J. Electrochem. Soc. 2009, 156, 125−130. (26) Kharkwal, A.; Deepa, M.; Joshi, A. G.; Srivastava, A. K. ChemPhysChem 2011, 12, 1176−1188. (27) Sroog, C. Prog. Polym. Sci. (U.K.) 1991, 16, 561−694. (28) Wang, L.; Goodloe, G.; Stallman, B.; Cammarata, V. Chem. Mater. 1996, 8, 1175−1181. (29) Wang, L.; Wang, Q.; Cammarata, V. J. Electrochem. Soc. 1998, 145, 2648−2654. (30) Cammarata,V.; Hao, N.; Metz, J.; Liang, J. ACS Symposium Series; ACS: Washington DC, 2003; Vol. 832, pp 59−74. (31) Wei, H.; Yan, X.; Li, Y.; Wu, S.; Wang, Y. A.; Wei, S.; Guo, Z. J. Phys. Chem. C. 2012, 116 (7), 4500−4510. (32) Li, Y.; Patil, R.; Wei, S.; Guo, Z. J. Phys. Chem. C. 2011, 115 (46), 22863−22869. (33) León-Silva, U.; Nicho, M.; Hu, H.; Cruz-Silva, R. Sol. Energy Mater. Sol. Cells 2007, 91, 1444−1448. (34) Hong, S. Y.; Park, S. M. J. Phys. Chem. B 2005, 109, 9305−9310. (35) Plesu, N.; Kellenberger, A.; Mihali, M.; Vaszilcsin, N. J. NonCryst. Solids 2010, 356, 1081−1088. (36) Cui, S. Y.; Park, S. M. Synth. Met. 1999, 105, 91−98. (37) Wei, Y.; Sun, Y.; Tang, X. J. Phys. Chem. 1989, 93, 4878−4881. (38) Polleux, J.; Pinna, N.; Antonietti, M.; Niederberger, M. J. Am. Chem. Soc. 2005, 127, 15595−15601. (39) Tocchetto, A.; Glisenti, A. Langmuir 2000, 16, 6173−6182. (40) Ingham, B.; Chong, S. V.; Tallon, J. L. J. Phys. Chem. B. 2005, 109, 4936−4940. 16293


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