The effect of boron trifluoride diethyl etherate on electrochemical polymerization and surface morphology of conjugated porous polymer poly(4,4′,4″-Tris(9-carbazolyl)triphenylamine)

Journal Pre-proof The effect of boron trifluoride diethyl etherate on electrochemical polymerization and surface morphology of conjugated porous polymer poly(4,4′,4″-Tris(9carbazolyl)triphenylamine) Jingdang Chai, Yingying Zhang, Fen Liu, Hui Zhang, Xinxin Zhang, Jingkun Xu, Ge Zhang PII:

S1572-6657(19)30770-2

DOI:

https://doi.org/10.1016/j.jelechem.2019.113502

Reference:

JEAC 113502

To appear in:

Journal of Electroanalytical Chemistry

Received Date: 18 June 2019 Revised Date:

16 September 2019

Accepted Date: 17 September 2019

Please cite this article as: J. Chai, Y. Zhang, F. Liu, H. Zhang, X. Zhang, J. Xu, G. Zhang, The effect of boron trifluoride diethyl etherate on electrochemical polymerization and surface morphology of conjugated porous polymer poly(4,4′,4″-Tris(9-carbazolyl)triphenylamine), Journal of Electroanalytical Chemistry (2019), doi: https://doi.org/10.1016/j.jelechem.2019.113502. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.

The

effect

of

boron

trifluoride

diethyl

etherate

on

electrochemical polymerization and surface morphology of conjugated

porous

polymer

poly(4,4',4"-Tris(9-carbazolyl)triphenylamine) Jingdang Chai‡,a, Yingying Zhang‡,a, Fen Liub, Hui Zhangc, Xinxin Zhanga, Jingkun Xu*,b,d , and Ge Zhang*,b a

School of Pharmacy, Jiangxi Science and Technology Normal University, Nanchang

330013, P. R. China b

School of Chemistry and Chemical Engineering, Jiangxi Science and Technology

Normal University, Nanchang 330013, P. R. China c

National Laboratory of Solid State Microstructures, College of Engineering and

Applied Sciences and Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China d

College of Chemistry and Molecular Engineering, Qingdao University of Science &

Technology, Qingdao 266042, P. R. China *Corresponding author: E-mail address: Jingkun Xu ([email protected], [email protected].) Ge Zhang ([email protected]) ‡

These authors contributed equally to this work.

1

Abstract: We reported the fabrication of conjugated porous polymer films based on 4,4',4"-Tris(9-carbazolyl)triphenylamine

(TCTA)

using

electrochemical

polymerization in CH2Cl2 containing different ratios of boron trifluoride diethyl etherate (BFEE). The oxidation potential of TCTA in CH2Cl2 with 20 vol % BFEE was measured to be only 0.28 V vs. Ag/AgCl, which was lower than that determined in pure CH2Cl2 (0.72 V vs. Ag/AgCl). Also, PTCTA films obtained from this medium showed better electrochemical behavior. And Fourier Transform Infrared spectra were used for structural analysis of polymers. From Scanning Electron Microscopy for surface morphological analysis, we founded that different percentages of BFEE were important in the control of the resulting surface morphology. Keywords: conjugated porous polymer; electrochemical polymerization; boron trifluoride diethyl etherate; surface morphology

2

1. Introduction Porous materials have attracted much attention due to their vital roles in many fields of science and technology. They have been applied to gas storage [1], sensing [2], luminescence [3], catalysis [4], energy transfer [5], and electric energy storage[6]. Depending on the nature of the building blocks, the porous materials can be divided into three main groups: inorganic, organic, and inorganic–organic hybrid porous materials [7]. Among them, conjugated porous polymers (CPPs) are most studied currently in the field of organic porous materials due to their unique properties, such as π-conjugated skeletons, adjustable pore size, and high specific surface area [8,9]. CPPs show great potential for challenging energy and environmental issues because they could complementary utilize π-conjugated skeletons and nanopores for functional exploration [10-12]. Thus, it is very meaningful to design and develop new CPPs or discover new properties of existing CPPs in order to expand their applications. As we all known, the preparation method and condition have great influence on the properties of CPPs. At present, the main preparation method for CPPs is chemical synthesis and the obtained polymers are usually powder, which are insoluble and unprocessable, thus precluding the fabrication of thin films for applications [13-15]. Importantly, this method requires expensive catalysts and harsh experimental conditions, which limit their applications. Delightfully, many researchers have discovered that electrochemical polymerization is an effective method for the preparation of CPPs films, and the porosity and specific surface area of obtained polymers are comparable to that obtained using chemical synthesis. What’s more, the electrochemical polymerization is high sensitivity, low cost, simplicity, and convenience [16-18]. The polymer films can be easily obtained, and the thickness, size, and shape of these films can be controlled conveniently. The influence of electrochemical polymerization conditions on film thickness has been studied and reported in recent years. Recently, more and more attentions have been paid to the effect of electrochemical polymerization conditions on film surface morphology 3

[19,20]. For example, Guittard group [21] and Wang group [22] reported the factors (monomers, electrochemical polymerization method, electrolyte, and trace water) have great effects on the surface morphology of CPPs. Moreover, solvents also have great effect on the surface morphology of CPPs. Usually, the common solvents include neutral solvents (acetonitrile, CH2Cl2, ionic liquids, ethyl alcohol, and propylene carbonate) and middle strong Lewis acid (boron trifluoride diethyl etherate, BFEE). It is reported that BFEE could interact with aromatic monomers and reduce their oxidation potential, which facilitates the formation of high-quality free-standing films [23,24]. So the introduction of BFEE facilitates the electrochemical polymerization of CPPs and influences the surface morphology of CPPs. To our knowledge, there are few reports about the effect of introducing BFEE on the electrochemical polymerization and surface morphology of CPPs. In this work, we chose carbazole and triphenylamine (TPA) units to design the CPPs,

whereas

multiple

carbazole

units

were

designed

for

site-specific

electrochemical polymerization, and TPA were employed to help the development of three-dimensional

porous

skeletons

[25,26].

So

poly(4,4',4"-Tris(9-carbazolyl)triphenylamine) (PTCTA) was synthesized by direct electrochemical

polymerization

of

corresponding

monomer

4,4',4"-Tris(9-carbazolyl)triphenylamine (TCTA, Fig. 1) in pure CH2Cl2 solution and CH2Cl2-BFEE mixtures at 100 mV s-1 scan rate and the surface morphology of PTCTA was also studied. The characterizations of polymers were performed by using Fourier Transform Infrared spectra (FT-IR) for structural analysis, Cyclic Voltammetry (CV) for electrochemical analysis, and Scanning Electron Microscopy (SEM) for morphological analysis. 2. Experimental 2.1 Materials 4,4',4"-Tris(9-carbazolyl)triphenylamine (TCTA) was purchased from TCI Company (Shanghai, China). Tetrabutylammonium hexafluorophosphate (Bu4NPF6), 4

anhydrous dichloromethane, and BFEE were purchased from J&K Chemical (Shanghai, China). All reagents were used without further purification. 2.2 Electrochemical polymerization The detail information of all electrochemical tests and polymerization were listed in Supporting Information. 2.3 FTIR-ATR measurements Infrared spectra were acquired with a Bruker Vertex 70 FT-IR spectrometer with samples in KBr pellets. 2.4 SEM images The images of obtained thin films in solutions including the various ratios of BFEE were taken by using SEM on TESCAN MIRA3. SEM analysis was performed at an accelerating voltage of 50 kV. 3. Results and Discussion 3.1 The effect of BFEE on the electrochemical polymerization of TCTA The anodic polarization curves of the TCTA monomer in CH2Cl2 solution with 0, 20, and 40 vol % BFEE containing 0.1 mol/L Bu4NBF6 were studied (Fig. 2). The onset potential of oxidation of TCTA was initiated at 0.72, 0.28, and 0.31 V, respectively. Obviously, when introducing BEFF, the onset oxidation potentials of TCTA were all much lower than that in CH2Cl2–Bu4NBF6 (0.1 M), because the interaction of BFEE and TCTA formed π-complexes and the corresponding resonance stability of TCTA could be reduced, which made its electron much easier lost [24]. Generally, a lower onset oxidation potential can lead to easier oxidation of the 5

monomer at given applied potential. This indicated that the oxidations of TCTA in CH2Cl2–BFEE mixtures were much easier than that in pure CH2Cl2. It should be noted that the onset oxidation potential of TCTA increased when the ratio of BFEE increased from 20% to 40%. In other words, the introduction of appropriate BFEE was more helpful to reduce the onset oxidation potential. Fig. 3 showed the cyclic voltammograms (CVs) of the TCTA monomer in CH2Cl2 with 0, 20, and 40 vol % BFEE containing Bu4NBF6 (0.1 mol/L) on a Pt wire electrode. The successive cycling led to a progressively increased current, reflecting the deposition and thickness increasing of the PTCTA films onto the electrode. Moreover, the peak potentials shifted to higher potential because the electrical resistance of the polymer film increased, which needed an overpotential to overcome. As can be seen in Fig. 3, there were three redox systems in the subsequent cycles, demonstrating that the investigated compound underwent multistage oxidation in different solvent systems. According to the work reported by Karon [27], the initial two steps were the formation of stable radical cation or dication in the TPA unit and the two stages of oxidation were reversible. And the third step corresponded to the formation of the reactive radicals in carbazole moiety, but this further oxidation was irreversible. From Fig. 3a, the onset of TCTA oxidation was estimated to be 0.72 V in pure CH2Cl2 solution, and the corresponding reversible peaks occurred at 0.89 V (Epa1), 0.70 V (Epc1), 1.10 V (Epa2), and 0.95 V (Epc2), respectively. And the irreversible peak occurred at 1.40 V. When introducing BFEE, the anodic oxidation potentials of TCTA were decreased obviously (Fig. 3b and 3c). And the actual 6

nucleation scope was reduced with increasing anodic oxidation potentials in the same potential range. These peaks were still observed in CVs of TCTA in CH2Cl2-BFEE mixture, but they were not sharp. When introducing BFEE, the current density obviously increased, which suggested that BFEE contributed to the electrochemical polymerization of TCTA. For investigating the polymerization sites of monomer, the FT-IR spectra of the monomer and the corresponding polymers were investigated. From Fig. 4, there was no apparent difference in the FT-IR spectra of polymers prepared from different systems, indicating these obtained polymers had similar structure. In Fig. 4, the band of PTCTA and TCTA at 3044 cm-1 were assigned to the stretching of aromatic C-H bonds. And polymers and the monomer showed very similar IR absorptions in the range of 1200-1600 cm-1 being associated with C-N stretch, and the skeleton vibration of the benzene ring. In Fig. 4a and S1, the bands of TCTA at 724 and 750 cm-1 were assigned to the out-of-plane bending vibration of 1,2-disubsubstituted benzene ring on carbazole [28]. After electrochemical polymerization, polymers had peak absorptions at 875, 802, and 745 cm-1, which indicated the presence of the 1,2,4-trisubstitution of benzene ring [29]. The results were consistent with the work reported by Karon [30]. Therefore, it can be reasonably deduced that the polymerization of TCTA occur at 3,6 positions. The redox behavior of the obtained polymer films from CH2Cl2 solutions having different ratios BFEE were investigated in the monomer-free MeCN-Bu4NPF6 (0.1 M) solution (see Fig. 5). The CVs showed broad redox peaks and a linear relationship 7

between peak current and scan rate characteristic of well-adhered polymer deposits where the current was not diffusion-controlled. Besides, the calculated jp,a/jp,c values (jp,a or jp,c is calculated as the ratio between anodic or cathodic peak current density and potential scan rate) of PTCTA in CH2Cl2 with 20 vol % BFEE were close to 1.0, better than those of PTCTA in pure CH2Cl2 solution and CH2Cl2 with 40 vol % BFEE, indicating its better redox reversibility [31]. The long-term redox stability of PTCTA films electrodeposited from pure CH2Cl2

and

CH2Cl2-BFEE

mixtures

was

studied

in

the

monomer-free

MeCN-Bu4NPF6 (0.1 M) at potential scan rate of 150 mV s-1. As shown in Fig. 6a, there was 56.02% exchange charge amount of polymer films prepared from pure CH2Cl2 solution when the scanning cycle was 400 in the potential scan range 0.7 to 1.3 V. When the polymer films were prepared from CH2Cl2-BFEE mixtures, the exchange charge amount retention ratio increased to 71.97% (20% BFEE, Fig. 6b) and 61.82% (40% BFEE, Fig. 6c). This showed that PTCTA film exhibited best stability when introducing BFEE, because BFEE could reduce the onset oxidation potential of TCTA [32]. Compared Fig. 6b and Fig. 6c, the retention ratio reduced when too much BFEE was introduced, which was consistent with that obtained from the anodic polarization curves in Fig. 2. 3.2 The effect of BFEE on the surface morphology of PTCTA In order to study the effect of BFEE on surface morphology of PTCTA, the SEM images of PTCTA electrodeposited by constant potential (the electrodeposited potentials: 1.40 V (a), 0.9 V (b), and 0.95 V (c)) at various imposed times (5, 10, 30, 8

and 60 s) in pure CH2Cl2 and CH2Cl2-BFEE mixtures were showed in Fig. 7. The electropolymerization in pure CH2Cl2 solution clearly displayed the whole evolution process of the surface morphology. It was obvious that a large number of small hollow nanoballs were fabricated at t = 5 s. Then, their sizes enlarged as t increased from 10 to 60 s. When t = 30 s, some open-top tubes on the surface of the nanoballs were observed. When t increased to 60 s, the numbers of the open-top tubes increased. For 20% BFEE system, it showed that many nanorods were formed at t = 5 s. But the surface morphology suddenly changed from original rods to cauliflower-like particles after 10 s, and their size enlarged as t increased. It should be attributable to that the rate of electrochemical polymerization was fast when introducing BFEE, which was confirmed by the results displayed in Fig. 3. When the ratio of BFEE increased from 20% to 40%, lots of nanorods and nanoballs were generated at t = 5 s due to the faster electrochemical polymerization rate. As t increased, the clusters appeared. From these SEM images, the introduction of BFEE obviously increased the polymerization rate of TCTA. 4. Conclusions In summary, a CPP films PTCTA have been successfully synthesized by electrochemical deposition. And a series of experiments showed PTCTA films obtained from CH2Cl2 with 20 vol % BFEE had better electrochemical behavior. The characterizations of the polymer were performed by using FT-IR spectra for structural analysis. Moreover, from the SEM, we observed that different percentages of BFEE are extremely important in the control of the resulting surface morphology. When 9

introducing BFEE, the rate of polymerization obviously increases and the surface morphology of PTCTA changes from nanotubes to nanorods and nanoballs. Acknowledgments We are grateful to the Innovation Driven “5511” Project of Jiangxi Province (Grant No. 20165BCB18016), the Natural Science Foundation of Jiangxi Province (20181BAB216011), Project of Jiangxi Educational Committee (GJJ180633), Scientific Research Foundation for Doctors in Jiangxi Science and Technology Normal University (2017BSQD006). References [1] J. Liu, R. Zou, Y. Zhao, Recent Developments in Porous Materials for H2 and CH4 Storage, Tetrahedron Lett. 57 (2016) 4873-4881. [2] N. Sang, C. Zhan, D. Cao, Highly Sensitive and Selective Detection of 2,4,6-trinitrophenol Using Covalent-Organic Polymer Luminescent Probes, J. Mater. Chem. A 3 (2015) 92-96. [3] J.X. Jiang, A. Trewin, D.J. Adams, A.I. Cooper, Band Gap Engineering in Fluorescent Conjugated Microporous Polymers, Chem. Sci. 2 (2011) 1777-1781. [4] C. Su, R. Tandiana, B. Tian, A. Sengupta, W. Tang, J. Su, K.P. Loh, Visible-Light Photocatalysis of Aerobic Oxidation Reactions Using Carbazolic Conjugated Microporous Polymers, ACS Catal. 6 (2016) 3594-3599. [5] C. Gu, N. Huang, Y. Chen, H. Zhang, S. Zhang, F. Li, Y. Ma, D. Jiang, Porous Organic Polymer Films with Tunable Work Functions and Selective Hole and Electron Flows for Energy Conversions, Angew. Chem., Int. Ed. 55 (2016) 10

3049-3053. [6] Y. Kou, Y.H. Xu, Z.Q. Guo, D.L. Jiang, Supercapacitive Energy Storage and Electric Power Supply Using an Aza-Fused p-Conjugated Microporous Framework, Angew. Chem., Int. Ed. 50 (2011) 8753-8757. [7] H. Bildirir, V.G. Gregoriou, A. Avgeropoulos, U. Scherfd, C.L. Chochos, Porous Organic Polymers as Emerging New Materials for Organic Photovoltaic Applications: Current Status And Future Challenges, Mater. Horiz. 4 (2017) 546-556. [8] F. Vilela, K. Zhang, M. Antonietti, Conjugated Porous Polymers for Energy Applications, Energy Environ. Sci. 5 (2012) 7819-7832. [9] L.N. Jennifer, R.D. William, Conjugated Porous Polymers for TNT Vapor Detection, ACS Macro Lett. 2 (2013) 423-426. [10] Y.L. Zhu, Y.J. Ji, D.G. Wang, Y. Zhang, H. Tang, X.R. Jia, M. Song, G.P. Yu, G.C. Kuang, BODIPY-Based Conjugated Porous Polymers for Highly Efficient Volatile Iodine Capture, J. Mater. Chem. A. 5 (2017) 6622-6629. [11] Y.Z. Liao, J. Weber, B.M. Mills, Z.H. Ren, C.F.J. Faul, Highly Efficient and Reversible Iodine Capture in Hexaphenylbenzene-Based Conjugated Microporous Polymers, Macromolecules 49 (2016) 6322-6333. [12] D. Robert, I.C. Andrew, J.A. Dave, Nanoporous Organic Polymer Networks, Prog. Polym. Sci. 37 (2012) 530-563. [13] M.P. Tsyurupa, V.A. Davankov, Porous Structure of Hypercrosslinked Polystyrene: State-of-The-Art Mini-Review, React. Funct. Polym. 66 (2006) 768-779. [14] L. Chen, Y. Honsho, S. Seki, D.L. Jiang, Light-Harvesting Conjugated 11

Microporous Polymers: Rapid and Highly Efficient Flow of Light Energy with a Porous Polyphenylene Framework as Antenna, J. Am. Chem. Soc. 132 (2010) 6742-6748. [15] M.G. Schwab, A. Lennert, J. Pahnke, G. Jonschker, M. Koch, I. Senkovska, M. Rehahnd, S. Kaskel, Nanoporous Copolymer Networks Through Multiple Friedel– Crafts-alkylation—Studies on Hydrogen and Methane Storage, J. Mater. Chem. 21 (2011) 2131-2135. [16] H. Bildirir, I. Osken, T. Ozturk, A. Thomas, Reversible Doping of a Dithienothiophene-Based Conjugated Microporous Polymer, Chem. Eur. J. 21 (2015) 9306-9311. [17] C. Gu, N. Huang, J. Gao, F. Xu, Y.H. Xu, D.L. Jiang, Controlled Synthesis of Conjugated Microporous Polymer Films: Versatile Platforms for Highly Sensitive and Label-Free Chemo- and Biosensing, Angew. Chem. Int. Ed. 53 (2014) 4850-4855. [18] H.H. Zhang, Y.N. Zhang, C. Gu, Y.G. Ma, Electropolymerized Conjugated Microporous Poly(zincporphyrin) Films as Potential Electrode Materials in Supercapacitors, Adv. Energy Mater. 10 (2015) 1402175-1402180. [19] C. Gu, Y. Chen, Z. Zhang, S. Xue, S. Sun, K. Zhang, C. Zhong, H. Zhang, Y. Pan, Y. Lv, Y. Yang, F. Li, S. Zhang, F. Huang, Y. Ma, Electrochemical Route to Fabricate Film-Like Conjugated Microporous Polymers and Application for Organic Electronics, Adv. Mater. 25 (2013) 3443-3448. [20] C. Gu, N. Huang, Y. Wu, H. Xu, D. Jiang, Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity, 12

Angew. Chem., Int. Ed. 54 (2015) 11540-11544. [21] G.R. Chagas, T. Darmanin, F. Guittard, One-Step and Templateless Electropolymerization Process Using Thienothiophene Derivatives to Develop Arrays of Nanotubes and Tree-like Structures with High Water Adhesion, ACS Appl. Mater. Inter. 8 (2016) 22732-22743. [22] S.L. Bai, Q. Hu, Q. Zeng, M. Wang, L.S. Wang, Variations in Surface Morphologies, Properties, and Electrochemical Responses to Nitro-Analyte by Controlled Electropolymerization of Thiophene Derivatives, ACS Appl. Mater. Inter. 10 (2018) 11319-11327. [23] L. Zou, X.M. Duan,·W.Q. Zhou, H. Zhang, S. Chen, J.D. Chai, X. Liu, L. Shen, J.K. Xu, G. Zhang, Electrochemical capacitive performance of free-standing polyindole film and effect of introducing alkyl chain connecting two indoles, J Mater. Sci.-Mater. El. 8 (2019) 7850-7857. [24] L. Zou, Y.P. Wen, H. Zhang, J.D. Chai, X.M. Duan,·L. Shen, G. Zhang, J.K. Xu, Highly

Sensitive

Fluorescent

Sensor

Based

on

Electrosynthesized

Poly(Fmoc-L-serine) Enables Ultra-trace Analysis of Cr2O72- in Water and Agro-product Samples, Sensor. Actuat B-Chem. 277 (2018) 394-400. [25] P.C. Alex, P. Eduard, S. Ullrich, Silicon- or Carbon-Cored Multifunctional Carbazolyl Monomers for the Electrochemical Generation of Microporous Polymer Films, Macromolecules 49 (2016) 8041-8047. [26] Z. Fang, V. Chellappan, R.D. Webster, L. Ke, T.F. Zhang, B. Liu, Y.H. Lai, Bridged-triarylamine Starburst Oligomers as Hole Transporting Materials for 13

Electroluminescent Devices, J. Mater. Chem. 22 (2012) 15397-15404. [27] K. Karon, M. Lapkowski, A. Dabuliene, A. Tomkeviciene, N. Kostiv, J.V. Grazulevicius, Spectroelectrochemical Characterization of Conducting Polymers from Star-shaped Carbazole-triphenylamine Compounds, Electrochim. Acta. 154 (2015) 119-127. [28] C. Gu, T. Fei, M. Zhang, C.N. Li, D. Lu, Y.G. Ma, Electrochemical Polymerization Films for Highly Efficient Electroluminescent Devices and RGB Color Pixel, Electrochem. Commun. 12 (2010) 553-556. [29] H. Macit, S. Sen, M. Sacak, Electrochemical synthesis and characterization of polycarbazole, J Appl. Polym. Sci. 96 (2005) 894-898. [30] K. Karon, M. Lapkowski, Carbazole electrochemistry: a short review, J Solid State Electrochem. 19 (2015) 2601-2610. [31] S.L.

Ming,

S.J. Zhen,

Thiadiazolo[3,4-c]pyridine

as

K.W. an

Lin,

Acceptor

L.

Zhao,

toward

J.K.

Xu,

B.Y.

Fast-Switching

Lu,

Green

Donor-Acceptor-Type Electrochromic Polymer with Low Bandgap, ACS Appl. Mater. Inter. 7 (2015) 11089-11098. [32] Y.S. Zhang, B.Y. Lu, L.Q. Dong, H. Sun, D.F. Hu, H.K. Xing, X.M. Duan, S. Chen, J.K. Xu, Solvent Effects on the Synthesis, Characterization and Electrochromic Properties of Acetic Acid Modified Polyterthiophene, Electrochim. Acta. 220 (2016) 122-129.

14

Fig. 1 Chemical structure of TCTA.

Fig. 2 Anodic oxidation curves of TCTA in CH2Cl2 with 0 (a), 20 (b), and 40 vol % (c) BFEE containing 0.1 mol/L Bu4NBF6 on a Pt working electrode. Potential scan rate: 50 mV s-1.

a

Fig. 3 CVs of TCTA in 0 (a), 20 (b), and 40 vol % (c) BFEE containing 0.1 mol/L Bu4NBF6 on a Pt working electrode. Potential scan rate: 100 mV s-1.

Fig. 4 FT-IR spectra of the monomer TCTA (a) and the polymer PTCTA electrodeposited from CH2Cl2 with 0 (b), 20 (c), and 40 vol % (d) BFEE containing 0.1 mol/L Bu4NBF6.

Fig. 5 Cyclic voltammograms of PTCTA electrodeposited from CH2Cl2 with 0 (a), 20 (b), and 40 vol % (c) BFEE containing 0.1 mol/L Bu4NBF6 on a Pt working electrode in the monomer-free MeCN-Bu4NPF6 (0.1 mol/L) at potential scan rates of 300, 275, 250, 225, 200, 175, 150, 125, 100, 75, 50, and 25 mV s-1. Right column: absolute values of redox peak current densities vs. potential scan rates. jp is the absolute value of the peak current density, and jp,a and jp,c denotes the absolute value of the anodic and cathodic peak current densities, respectively.

Fig. 6 Long-term cyclic voltammograms of PTCTA electrodeposited from CH2Cl2 with 0 (a), 20 (b), and 40 vol % (c) BFEE containing 0.1 mol/L Bu4NBF6 on a Pt working electrode in the monomer-free MeCN-Bu4NPF6 (0.1 mol/L) at potential scan rate of 150 mV s-1.

Fig. 7 SEM images of PTCTA electrodeposited at various imposed times (5, 10, 30, and 60 s) in CH2Cl2 with 0 (a), 20 (b), and 40 (c) vol % BFEE containing 0.1 mol/L Bu4NBF6 on ITO glass electrodes. (The electrodeposited potentials: 1.40 V (a), 0.9 V (b), and 0.95 V (c))

Highlights: 1. Conjugated porous polymer films were electrochemically prepared. 2. The BFEE was extremely important in the control of the resulting nanostructures. 3. The introduction of BFEE discovered the new properties and may expand

applications of conjugated porous polymers.