High-k Polymer Nanocomposites Filled with Hyperbranched

Subscriber access provided by - Access paid by the | UCSB Libraries

Applications of Polymer, Composite, and Coating Materials

High-k Polymer Nanocomposites Filled with Hyperbranched Phthalocyanine Coated BaTiO3 for High Temperature and Elevated Field Applications Wenhan Xu, Gang Yang, Lan Jin, Jie Liu, Yunhe Zhang, Zhicheng Zhang, and Zhenhua Jiang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b01129 • Publication Date (Web): 15 Mar 2018 Downloaded from http://pubs.acs.org on March 16, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

High-k Polymer Nanocomposites Filled with Hyperbranched Phthalocyanine Coated BaTiO3 for High Temperature and Elevated Field Applications Wenhan Xu1, Gang Yang1, Lan Jin1, Jie Liu1, Yunhe Zhang1*, Zhicheng, Zhang2*, Zhenhua Jiang1 1

Key Laboratory of High Performance Plastics, Ministry of Education, College of

Chemistry, Jilin University, Changchun, 130012, P.R. China. 2

Department of Applied Chemistry, School of Science, Xi’an Jiaotong University,

Xi’an, 710049, P.R. China. KEYWORDS: dielectric material, poly (ether sulfone), surface modification, hyperbranched phthalocyanine, composites

ABSTRACT

Two sets of thermal stable nanocomposites were fabricated by using engineering plastics poly (ether sulfone) (PES) as a matrix and phthalocyanine molecules (CuPc) or hyperbranched phthalocyanine (HCuPc) coated barium titanate nanoparticles (BT) as filler for high electric field and high temperature dielectric applications. By side-byside comparison, the hyperbranched coating is finely addressed for enhancing the dielectric response and breakdown strength of the composites. Specifically, BT1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 39

HCuPc/PES exhibits 40% lower dielectric loss and about 110% larger breakdown strength than BT-CuPc/PES. The addition of hyperbranched phthalocyanine may enhance the compatibility and dispersion of the ceramic fillers in polymer matrix and reduces the charge carrier between the filler and matrix. Meanwhile, high dielectric constant, high breakdown and low dielectric loss are well remained in the composites filled with hyperbranched phthalocyanine modified BT from room temperature to 150 o

C. The discharged energy density of the composites (20 vol% BT-HCuPc/PES) can

reach 2.0 J/cm3 at 300 MV/m, about 166% of that of polymer matrix (1.2 J/ cm3). Our findings on hyperbranched coating structure could be applicable to other ceramicpolymer composites to enhance their dielectric response.

1. Introduction With the increased demand for high-pulse power equipment, electronic power systems and compact electronic devices, electric energy storage devices with high energy and huge power densities are highly requested.1-2 Compared with batteries and supercapacitors, dielectric capacitors exhibit superior high charge-discharge rate, which is irreplaceable in the electronics industry. 3-4 Among all the dielectric materials for conventional capacitors, metalized polymer films (c.a. biaxially oriented polypropylene (BOPP)) are more attractive for their high dielectric strength, easy processing, low cost and low dielectric loss.5-8 However, the low dielectric constant of polymer dielectrics (about 2-10) significantly limits their energy density as suggested by equation (1), 1

U = ∫ 𝐸 𝑑𝐷 = 2 𝜀0 𝜀𝐸𝑏 2 (1) 2 ACS Paragon Plus Environment

Page 3 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


where, D is the electric displacement, E is the applied electric field (Eb, the maximum E that can be applied on a dielectric material), ɛ0 represents the vacuum dielectric constant, and ɛ is the relative dielectric constant of the dielectric materials. Besides elevating the breakdown strength, enhancing the dielectric constant of dielectric materials is another option to achieve high electric density. Owing to the high dielectric constant of ceramics (c.a. barium titanate(BT)), they are mostly chosen as fillers to fabricate high-k polymeric composites. 9-20 However, the incorporation of ceramic particles into the polymer matrix usually leads to the aggregation. The charge concentration induced by the high permittivity fillers influence the electric field distribution in the composites.21 The aggregation and the inhomogeneous electric field would dramatically decrease the breakdown strength.22 As a result, the energy density could hardly be improved. Meanwhile, the interface formed between fillers and matrix is well addressed for the elevated dielectric loss at low frequency. That results into the significantly reduced discharging efficiency in the resultant composites as well. Modifying the surface of the inorganic fillers with organic compounds is a promising way to alleviate the aggregation of fillers in the polymer matrices and restrict the movement of charge carriers at the polymer–filler interfaces.910,23-31

According to Maxwell-Wagner theory and computer simulation results32-34, the dielectric constant of the composites will not increase much until the spherical fillers reaches 30-35 vol%. Above this threshold, the dielectric constant will obviously increase. However, the breakdown strength will decrease because the high loading 3 ACS Paragon Plus Environment


Page 4 of 39

content of filler will create effective electrical conduction path via interconnected interfaces. At the same time, the high loading content of inorganic fillers inevitably leads to the reduced processability and mechanical properties in the resultant composites. Therefore, to banlance the compliction between permittvity and other key performance, relatively low content of fillers is preferred in the dielectric composites. Phthalocyanine (Pc) is a class of organic semiconductor materials served in sensors, transistors and high-k composites.35-37 Recently, researchers use phthalocyanine as the coating materials on the ceramics to obtain high dielectric constant composites at low filler loading.38 For instance, high polarizable phthalocyanine has been attached on the surface of BT nanoparticles to obtain high dielectric constant three-phase composite.38 Besides high permittivity (c.a. 18) and low loss (0.03), rather high energy density has been achieved under an electric field of 250 MV/m in the resultant composites. Phthalocyanine coating could evidently increase the dielectric constant of the composites and reduce the filler loading. But the high electical conductivity of Pc limits others key dielectric performance (such as dielectric loss and breakdown strength) in the composites. Besides fillers, polymer matrix also plays a decisive role in the dielectric composites. The glass transition temperature and thermal decomposition temperature of the matrix usually determine the service temperature range of the composites.39-41 Conventional polymers generally have a low glass transition temperature and low dielectric constant, which limits the application area of the dielectric composites. Therefore, thermostable

4 ACS Paragon Plus Environment

Page 5 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


engineering plastics with high dipoler units (such as urea, sulfone and thiourea6,42) are ideal polymer matrix for high-k nanocomposites. In this work, a heat-resistant polymer with high dipole, poly (ether sulfone) (PES), is chosen as matrix and hyperbranched phthalocyanine (HCuPc) coated barium titanate nanoparticles (BT) are used as fillers to fabricate thermal stable dielectric composites. The semiconductor molecules (CuPc) may improve the permittivity of composites with relatively low BT loading content. To reduce the electronic conductivity of the CuPc, we introduce the high dipole insulation segment, “aryl-SO2-aryl” units, to form the hyperbranched phthalocyanine. The insulation segment may block carrier migration between the phthalocyanine molecules and would not affect the delocalization of the electrons inside the phthalocyanine molecules. The unique units are similar to PES backbone units, which may improve the compatibility between the fillers and the matrix and decrease the defects between BT and polymer matrix. On the other hand, the movable charge carriers between the filler and the matrix can be reduced by hyperbranched polymer chains. Meanwhile, the large dipole moment (4.3 D) in sulfone groups could flip under electric field, which may enhance the dielectric constant of the material. By side-by-side comparing the dielectric properties of three sets of composites (BT/PES, BT-CuPc/PES and BT-HCuPc/PES), the roles of HCuPc in improving the dielectric performances of the composites are finely addressed.

2. Experimental 2.1 Reagents and materials 5 ACS Paragon Plus Environment


Page 6 of 39

The BaTiO3 nanoparticles (BT) with an average diameter of 100 nm were purchased from Shandong Sinocera Functional Material Company, China. Poly (ether sulfone) (PES) was purchased from Changchun Jida Plastic Engineering Research Co., Ltd. 4Nitrophthalonitrile (Alpha Chemicals Co., Ltd.), Cuprous chloride (Tianjin Huadong Regent Factory), Hydrogen Peroxide Solution 30% Aqueous solution of 30 wt% H2O2 (Xilong Chemicals Company Co., Ltd), Anhydrous potassium carbonate (Sinopharm Chemical Reagent Co., Ltd), and N,N-dimethyl formamide (DMF, Tianjin Tiantai Fine Chemicals Co., Ltd) were all used as received. 2.2 Preparation of Core-Shell BT-CuPc hybrid filler and BT-HCuPc hybrid filler Uniform CuPc shells upon the surface of BT were prepared via a method described as below. BT (1.0 g) were dispersed in 25 ml H2O2 under ultrasonication and then refluxed for 4 hours. The mixture was centrifugated at 5000 rpm for 10 min, and the precipitant was collected and washed with deionized water and dried under 80 oC to obtain hydroxylated BaTiO3 nanoparticles (BT-OH). Subsequently, 0.8 g BT-OH was added into 25 ml DMF and treated under ultrasonic conditions before 0.16 g 4nitrophthalonitrile and 0.24 g potassium carbonate were added, followed by stirring at 80 oC under a N2 atmosphere for 6 h. Then the nanoparticles were collected by centrifugation to remove the unreacted 4-nitrophthalonitrile. After washed with deionized water and dried under vacuum at 80 oC for 24 h, the cyanided BaTiO3 nanoparticles (BT-CN) were prepared. Finally, 0.5 g BT-CN was dispersed in 100 ml DMF under ultrasonication for 4 h before the 0.3 g 4-nitrophthalonitrile and 0.03 g 6 ACS Paragon Plus Environment

Page 7 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CuCl were added to the dispersion. The precipitant was collected by centrifugation, rinsed with DMF for three times and deionized water twice. After drying under reduced pressure at 80 oC for 24 h, the phthalocyanine modified BaTiO3 nanoparticles (BTCuPc) were fabricated. The above BT-CN nanoparticles were grafted with a layer of hyperbranched phthalocyanines onto the surface involving the reaction of the BT-CN with the cyanoended monomers (BPS-CN). The detailed procedures were showed in Scheme 1 and described in supporting information.

2.3 Preparation of the Composite Films

Scheme 1. The overall fabrication procedure for core-shell structures of (a) hyperbranched modified BT-HCuPc, (b) in-situ synthesized BT-CuPc. 2.3 Preparation of BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites films



Page 8 of 39

BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites were prepared by a solution cast process. The designed amount of BT, BT-CuPc or BT-HCuPc nanoparticles were added into DMF and ultrasonicated for 1 h at room temperature, respectively. The well dispersed suspensions were added into PES/DMF solutions as desired. The mixture was stirred for another 2 h and cast onto a clean hot glass slides at 80 oC for 2 h and then 60 C for 24 h. The composite films with a thickness of 10-20 m were peeled off glass

o

slides at room temperature. The obtained nanocomposite films were named according to the volume fraction of corresponding nanoparticles, for example, BT-HCuPc-30/PES is referred to the composites made from PES filled with 30 vol% BT-HCuPc. 2.4 Characterization Fourier-transform infrared spectroscopy (FT-IR) images were conducted with a Nicolet Impact 410 FT-IR spectrophotometer over the range of 4000-400 cm−1. Scanning electron microscopy (SEM) images were obtained from a FEI Nova Nano 450 field emission. SEM system was operated with an accelerating voltage at 15 kV. All BT nanocomposites films samples subjected to test were coated with a layer of gold nanoparticles. Transmission electron microscopy (TEM) images were obtained by JEOL JEM-2100 instrument (acceleration voltage at 100 kV). All nanoparticles samples were dispersed into DMF and ultra-sonicated, then 1-2 drops of the resulting suspension were dropped onto carbon-coated copper grids and air-dried. Thermodynamics stability of nanoparticles (BT, BT-CN，BT-CuPc and BT-HCuPc) were measured via a thermogravimetric analysis (TGA) (Perkin Elmer Pyris TGA analyzer) over the temperature range of 80-800 oC at a heating rate of 20 oC/min-1 in air 8 ACS Paragon Plus Environment

Page 9 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


flow (20 mlmin-1). The dielectric properties of the films were measured with the frequency range 103 to 106 Hz from room temperature to 160 oC by 4294A Precision Impedance Analyzer (Agilent Technologies Co. Ltd.) and the applying voltage was 0.5 V. Electric displacement−electric field (D−E) loops and DC breakdown strength measurements were processed by a TREK 610C instrument (PolyK Technologies) at 100 Hz. All the films were sputtered by copper with diameter of 3.4 mm on both surfaces as electrodes.

3.Results and discussion 3.1 Structural characterization of BT-CuPc and BT-HCuPc Hybrid Particles FT-IR spectra of BT, BT-OH, BT-CN, BT-CuPc and BT-HCuPc are shown in Figure 1(a). Stronger absorption at 3300−3500 cm-1 in BT-OH nanoparticles could be detected in contrasted with that of the as-received BT, indicating that more −OH groups are introduced onto BT particles after treated with H2O2. For BT-CN, the absorptions at 1538 cm-1 and 1355 cm-1 corresponding to the asymmetric and symmetric −NO2 stretching vibrations disappear and new band at 1251 cm-1 associated with the Ar-O-Ba vibrations emerges. That indicates 4-nitrophthalonitrile has been successfully attached onto the surface of BT by reacting with –OH groups. The appearance of new peaks at 1583 cm-1 and 1484 cm-1 corresponding to the vibrations of C=C on the benzene rings and the peaks at 2234 cm−1 assigning to the −CN stretching vibration may further confirm the addition of cyano-ended group onto BT nanoparticles. The absorption corresponding to the −CN stretching vibration at 2234 cm−1 disappears in BT-CuPc suggesting the successful fabrication of BT-CuPc. Grafting hyperbranched 9 ACS Paragon Plus Environment


Page 10 of 39

phthalocyanines onto the BT-CN leads to the significant change in the FT-IR spectra as well. The peak height at 2235 cm-1 of the −CN stretching vibration is dropping since the cyano groups are practically consumed in BT-HCuPc. The emerged new peak at 1244 cm−1 is attributed to the synergistic effect of the Ar-O-Ba vibrations and the ArO-Ar vibrations. The bands at 1153 cm-1 and 1105 cm-1 are attributed to the vibrations of sulfonyl group of BPS and the peaks at 1724 cm-1 are assigned to the -C=N stretching of the conjugated system in phthalocyanine structure. In summary, all the results demonstrate that the successful modification on BT as suggested in Figure 1.

Figure 1. (a) FT-IR spectra of the as-received BT, BT-OH, BT-CN, and BT-HCuPc. (b) TGA curves of BT, BT-CN, BT-CuPc and BT-HCuPc. To further characterize the structure of nanoparticles, as shown in Figure 1(b), thermal gravimetric analysis (TGA) was performed on BT, BT-CN and BT-CuPc and BT-HCuPc nanoparticles. As indicated by these curves, both BT-CuPc and BT-HCuPc nanoparticles exhibit superior thermal stability. The temperature at 5% weight loss of BT-CuPc and BT-HCuPc is 345 oC and 407 oC, respectively. The relatively high 10 ACS Paragon Plus Environment

Page 11 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


decomposing temperature makes them suitable candidates to fill polymers for high temperature application. At 100~340 oC, these nanoparticles show reduced weight loss rates in the order of BT < BT-CNBT-CuPc/PES>BT13 ACS Paragon Plus Environment


Page 14 of 39

HCuPc/PES. That means the interfacial polarization between the hyperbranched phthalocyanine-coated BT (BT-HCuPc) and the polymer matrix is smaller than that of BT-CuPc, which could be ascribed to the significantly improved compatibility between the PES and HCuPc shell layer. The addition of either CuPc or HCuPc leads to improve compatibility between the PES matrix and BT particles. That may address the largest interfacial polarization observed in PES/BT composites. At the consistent frequency, the permittivity of the composites filled with the same BT particles is in the order of BT-CuPc/PES>BT-HCuPc/PES>BT/PES.

Figure 4. Relative permittivity (a, b, c)/ Dielectric loss tangent (d, e, f)/AC conductivity (g, h, i)) of the BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites.


Page 15 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4 (d)(e)(f) shows the dependence of dielectric loss tangent onto frequency as a function of BT contents. The addition of BT particles results into the gradually increased dielectric loss in all the composites. Differently, at low frequency, the dielectric loss of BT-HCuPc/PES composites is much smaller than BT-CuPc/PES and BT/PES composites with consistent BT content. As discussed above, the addition of BT particles into PES would form interface between BT and PES, and the interfacial polarization is responsible for the improved dielectric constant and thus the dielectric loss. The addition of CuPc onto the surface of BT particles would further increase the dielectric constant and loss owing to the semi-conductive nature of CuPc, which could be confirmed by the slightly increased conductivity as shown in Figure 4(h). However, the grafting of hyperbranched phthalocyanine may significantly improve the compatibility between BT particles and PES matrix, which may effectively depress the interfacial polarization induced high dielectric loss. Besides, the addition of insulating hyperbranched phthalocyanine layer may reduce the conductivity of BT-CuPc particles as well as suggested by Figure 4(i). As a result, BT-HCuPc/PES composites show the increased permittivity but well depressed dielectric loss. To more clearly show the dependence of dielectric performances onto the modification of BT particles, the dielectric properties of three composite systems with different filler volume fraction at 103 Hz are shown in Figure 5. BT-CuPc/PES composites exhibit the highest dielectric constant and reach 17 with 40 vol% BT-CuPc loading content. The smaller dielectric constant of BT-HCuPc/PES than that of BTCuPc/PES indicates that the polarization contributed by hyperbranched phthalocyanine 15 ACS Paragon Plus Environment


Page 16 of 39

is less than phthalocyanine. It may be explained by the fact that the conductivity of hyperbranched phthalocyanines is smaller, which could be confirmed by the reduced AC conductivity. The highest dielectric loss is observed in BT-CuPc/PES composites as shown in Figure 5(b), which is mainly attributed to the relatively high conductivity of CuPc. Notably, the dielectric loss of BT-HCuPc/PES composites is much lower than the other two kinds of composites. For example, the dielectric loss of BT-HCuPc40/PES is 0.054, which is only 46% of the BT-CuPc-40/PES and 57% of the BT40/PES respectively. That agrees well with the lowest ac conductivity obtained in BTHCuPc/PES as shown in Figure 5(c), where the conductivity of BT-HCuPc/PES is less than 40% of BT-CuPc/PES. It has been well addressed that the dielectric loss of composites (c.a. BT/PES) at low frequency is mainly originating from the interfaces between two materials with varied dielectric performances. In present case, the attaching of semi-conductive CuPc onto BT particles leads to further improved dielectric loss owing to the conduction loss of CuPc. However, grafting the hyperbranched phthalocyanine may effectively depress the migration of charge carriers of CuPc. Besides, the interfacial polarization is significantly reduced for the improved compatibility of BT-HCuPc with PES matrix. Both effects may address the depressed conductivity together with the induced dielectric permittivity and dielectric loss in the composites.


Page 17 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. Comparison of (a) dielectric constant, (b) dielectric loss, (c) AC conductivity of BT/PES, BT-CuPc/PES, BT-HCuPc/PES with varied composition.

Figure 6. Breakdown strength of BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites at (a) 25 oC and (b) 150 oC. Figure 6 shows the breakdown strength (Eb) of all the composites measured at 25 oC and 150 oC. In the composites, the addition of BT particles leads to the reduced Eb. As loading content increases from 0 to 40 vol%, Eb of BT-HCuPc/PES at 25 oC is linearly decreased from 340 MV/m to 220 MV/m. However, Eb of BT/PES and BT-CuPc/PES is quickly reduced from 340 MV/m to below 150 MV/m with even 10 vol% of BT particles loaded. At 150 oC, the similar decreasing tendency is observed in all the three sets of composites as shown in Figure 6(b). The Eb reducing speed of BT-HCuPc/PES composites is much slower than that of BT and BT-CuPc filled composites 17 ACS Paragon Plus Environment


Page 18 of 39

correspondingly. In most cases, the failure of polymer dielectric is caused by the thermal breakdown, which is normally caused by tiny current produced by charge carriers in the dielectric. Under high electric field, the Joel heat generated from the leakage current is responsible for the formation of point defects and the loss of the Young’s modulus of the material. Therefore, the larger the conductivity would result into the reduced Eb. As discussed above, the adding of either BT or BT-CuPc into PES causes the increased dielectric constant and loss owing to the improved AC conductivity. Among the three sets of composites, BT-HCuPc/PES composites have the lowest dielectric loss and the conductivity, which may account for the highest Eb observed. 3.4 Dielectric thermal stability of the BT-HCuPc/PES composites For long term dielectric applications, the consistence of dielectric properties at elevated temperature is crucial as well, since low operating temperature would seriously limits the applications of the dielectrics. To show the dielectric thermal stability of BTHCuPc/PES composites, the dependence of their dielectric constant and loss onto the temperature is shown in Figure 7. Regardless of the BT-HCuPc loading content, the fluctuation of dielectric constant is within 5% at the temperature ranging from 25 oC to 150 oC, which means the dielectric constant is nearly independent onto the testing temperature. The dielectric loss of the composites is slightly increased with the temperature increasing but still remains at relatively low level. For example, with 20 vol% BT-HCuPc, the dielectric loss is only 0.05 at 150 oC. The excellent dielectric thermal stability should be attributed to the high Tg of PES (c.a. 220 oC) and the 18 ACS Paragon Plus Environment

Page 19 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


excellent thermal stability of hyperbranched phthalocyanine coated BT. The typical polymer dielectrics such as BOPP are usually allowed to be operated below 105 oC, and extra cooling system has to be designed for electric vehicles application operated at 150 o

C. The good stability of BT-HCuPc/PES makes it a better substitution of traditional

polymer dielectrics for high temperature applications.

Figure 7. Dielectric properties of BT-HCuPc/PES composites at 1 kHz as a function of temperature. 3.5 Energy storage properties of BT-HCuPc/PES nanocomposites The dielectric and energy storage properties of BT-HCuPc/PES composites under high electric field are investigated with displacement-electric field (D–E) loops. D-E loops of pristine PES and BT-HCuPc/PES composites at room temperature are compared in Figure 8(a). Similar to the pristine PES, all the composites show the linear dependence of displacement onto the electric field. Compared with PES, the electric displacements of the composites filled with BT-HCuPc are greatly enhanced due to the high permittivity of fillers. The introduction of BT-HCuPc is responsible for the broadened D-E loops. Calculated from the D-E loops, the discharged energy density of 19 ACS Paragon Plus Environment


Page 20 of 39

BT-HCuPc/PES with varied compositions is shown in Figure 8(b). As the filler volume fraction increases, the discharged energy density under the same electric field is elevated, which is consistent with the dielectric constant data. The discharged energy density of BT-HCuPc-20/PES composite reaches 2.0 J/cm3 at 300 MV/m, which is 1.66 times of pristine PES. Further increasing BT-HCuPc content (c.a. 30 vol%) leads to the reduced breakdown electric field and the lowered discharged energy density at Eb, although the discharged energy density under low electric field is larger. The chargedischarge efficiency of the composites is shown in Figure 8(c). Although the addition of BT particles leads to the reduction of efficiency, the efficiency of the composite bearing 20 vol% BT-HCuPc still remain as high as 84% under 300MV/m. That allows them to be operated under high electric field for long term.

Figure 8. D-E loops (a), discharged energy density (b) and discharged-charged efficiency (c) of the BT-HCuPc/PES composites under different electric field.

Conclusion By introducing hyperbranched phthalocyanine coating on the BT, the BTHCuPc/PES composites were fabricated. Compared with as-received BT and phthalocyanine molecules modified composites, BT-HCuPc/PES shows the dramatically enhanced dielectric response and breakdown strength. As a result, BT20 ACS Paragon Plus Environment

Page 21 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


HCuPc/PES composites show a similar level of dielectric loss and breakdown strength with polymer matrix while holding a much higher permittivity. In addition, the dielectric properties of the composites show excellent thermal stability and high energy density. This work might provide a way to enhance the dielectric response and breakdown strength of the ceramic-polymer composites. Author Information Corresponding Authors Yunhe Zhang: [email protected] Zhicheng Zhang: [email protected] ORCID Wenhan Xu: 0000-0002-4347-2601 Yunhe Zhang: 0000-0001-8483-6486 Zhicheng Zhang: 0000-0003-1871-117X Supporting Information The Supporting Information is details of the synthesis methods of Hyperbranched Phthalocyanine Coated BaTiO3 which is available free of charge on the ACS Publication website at DOI: xxx/xxx.xxx ACKNOWLEDGMENTS This work was financially supported by The National Natural Science Foundation of China (51573070), The National Key Research and Development Program of China (2017YFB0307601) and the Fundamental Research Funds for the Central Universities.



Page 22 of 39

REFERENCES 1. Sarjeant, W. J.; Zirnheld, J.; MacDougall, F. W., Capacitors. IEEE Transactions on Plasma Science 1998, 26 (5), 1368-1392. 2. Li, Q.; Wang, Q., Ferroelectric Polymers and Their Energy-Related Applications. Macromolecular Chemistry and Physics 2016, 217 (11), 1228-1244. 3. Chu, B. J.; Zhou, X.; Ren, K. L.; Neese, B.; Lin, M. R.; Wang, Q.; Bauer, F.; Zhang, Q. M., A dielectric polymer with high electric energy density and fast discharge speed. Science 2006, 313 (5785), 334-336. 4. Li, J. Y.; Zhang, L.; Ducharme, S., Electric energy density of dielectric nanocomposites. Applied Physics Letters 2007, 90 (13),192901. 5. Wang, J.-W.; Shen, Q.-D.; Bao, H.-M.; Yang, C.-Z.; Zhang, Q. M., Microstructure and Dielectric Properties of P(VDF−TrFE−CFE) with Partially Grafted Copper Phthalocyanine Oligomer. Macromolecules 2005, 38 (6), 2247-2252. 6. Chen, Q.; Shen, Y.; Zhang, S.; Zhang, Q. M., Polymer-Based Dielectrics with High Energy Storage Density. Annual Review of Materials Research 2015, 45 (1), 433-458. 7. Wang, J.-W.; Wang, Y.; Wang, F.; Li, S.-Q.; Xiao, J.; Shen, Q.-D., A large enhancement in dielectric properties of poly(vinylidene fluoride) based all-organic nanocomposite. Polymer 2009, 50 (2), 679-684.


Page 23 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


8. Chen, J.; Long, C.; Li, H.; Han, H.; Sun, R.; Xie, M., Double-stranded block copolymer with dual-polarized linker for improving dielectric and electrical energy storage performance. Polymer 2017, 127, 259-268. 9. Huang, X.; Jiang, P., Core–Shell Structured High-k Polymer Nanocomposites for Energy Storage and Dielectric Applications. Advanced Materials 2015, 27 (3), 546554. 10.

Kim, P.; Doss, N. M.; Tillotson, J. P.; Hotchkiss, P. J.; Pan, M. J.; Marder, S.

R.; Li, J. Y.; Calame, J. P.; Perry, J. W., High Energy Density Nanocomposites Based on Surface-Modified BaTiO3 and a Ferroelectric Polymer. Acs Nano 2009, 3 (9), 25812592. 11.

Li, J. J.; Seok, S. I.; Chu, B. J.; Dogan, F.; Zhang, Q. M.; Wang, Q.,

Nanocomposites of Ferroelectric Polymers with TiO2 Nanoparticles Exhibiting Significantly Enhanced Electrical Energy Density. Advanced Materials 2009,21 (2), 217-+. 12.

Zheng, L.; Liang, G.; Gu, A.; Yuan, L.; Guan, Q., Unique pure barium titanate

foams with three-dimensional interconnecting pore channels and their high-k cyanate ester resin composites at very low barium titanate loading. Journal of Materials Chemistry C 2016, 4 (45), 10654-10663. 13.

Yu, K.; Wang, H.; Zhou, Y.; Bai, Y.; Niu, Y., Enhanced dielectric properties

of BaTiO3/poly(vinylidene fluoride) nanocomposites for energy storage applications. Journal of Applied Physics 2013, 113 (3), 034105. 23 ACS Paragon Plus Environment


14.

Page 24 of 39

Wang, Y.; Cui, J.; Yuan, Q.; Niu, Y.; Bai, Y.; Wang, H., Significantly

Enhanced Breakdown Strength and Energy Density in Sandwich-Structured Barium Titanate/Poly(vinylidene fluoride) Nanocomposites. Advanced Materials 2015, 27 (42), 6658-6663. 15.

Pan, Z.; Yao, L.; Zhai, J.; Shen, B.; Liu, S.; Wang, H.; Liu, J., Excellent energy

density of polymer nanocomposites containing BaTiO3@Al2O3 nanofibers induced by moderate interfacial area. Journal of Materials Chemistry A 2016, 4 (34), 13259-13264. 16.

Luo, S.; Shen, Y.; Yu, S.; Wan, Y.; Liao, W.-H.; Sun, R.; Wong, C.-P.,

Construction of a 3D-BaTiO3 network leading to significantly enhanced dielectric permittivity and energy storage density of polymer composites. Energy & Environmental Science 2017, 10 (1), 137-144. 17.

Jiang, J.; Zhang, X.; Dan, Z.; Ma, J.; Lin, Y.; Li, M.; Nan, C.-W.; Shen, Y.,

Tuning Phase Composition of Polymer Nanocomposites toward High Energy Density and High Discharge Efficiency by Nonequilibrium Processing. ACS Applied Materials & Interfaces 2017, 9 (35), 29717-29731. 18.

Xu, N.; Hu, L.; Zhang, Q.; Xiao, X.; Yang, H.; Yu, E., Significantly Enhanced

Dielectric Performance of Poly(vinylidene fluoride-co-hexafluoropylene)-based Composites Filled with Hierarchical Flower-like TiO2 Particles. ACS Applied Materials & Interfaces 2015, 7 (49), 27373-27381.


Page 25 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


19.

Yu, D.; Xu, N.-x.; Hu, L.; Zhang, Q.-l.; Yang, H., Nanocomposites with

BaTiO3-SrTiO3 hybrid fillers exhibiting enhanced dielectric behaviours and energystorage densities. Journal of Materials Chemistry C 2015, 3 (16), 4016-4022. 20. Arjmand M.; Sundararaj U. Impact of BaTiO3 as Insulative Ferroelectric Barrier on the Broadband Dielectric Properties of MWCNT/PVDF Nanocomposites. Polymer Composites 2016, 37, 299-304. 21. Roscow, J. I.; Bowen, C. R.; Almond, D. P., Breakdown in the Case for Materials with Giant Permittivity. ACS Energy Letter 2017, 2(10), 2264-2269. 22.

Hao, Y.; Wang, X.; Bi, K.; Zhang, J.; Huang, Y.; Wu, L.; Zhao, P.; Xu, K.;

Lei, M.; Li, L., Significantly enhanced energy storage performance promoted by ultimate sized ferroelectric BaTiO3 fillers in nanocomposite films. Nano Energy 2017, 31, 49-56. 23.

Yang, K.; Huang, X.; Zhu, M.; Xie, L.; Tanaka, T.; Jiang, P., Combining

RAFT Polymerization and Thiol–Ene Click Reaction for Core–Shell Structured Polymer@BaTiO3 Nanodielectrics with High Dielectric Constant, Low Dielectric Loss, and High Energy Storage Capability. ACS Applied Materials & Interfaces 2014, 6 (3), 1812-1822. 24.

Xie, Y.; Yu, Y.; Feng, Y.; Jiang, W.; Zhang, Z., Fabrication of Stretchable

Nanocomposites with High Energy Density and Low Loss from Cross-Linked PVDF Filled with Poly(dopamine) Encapsulated BaTiO3. ACS Applied Materials & Interfaces 2017, 9 (3), 2995-3005. 25 ACS Paragon Plus Environment


25.

Page 26 of 39

Wu, Y.-H.; Zha, J.-W.; Yao, Z.-Q.; Sun, F.; Li, R. K. Y.; Dang, Z.-M.,

Thermally stable polyimide nanocomposite films from electrospun BaTiO3 fibers for high-density energy storage capacitors. RSC Advances 2015, 5 (56), 44749-44755. 26.

Song, Y.; Shen, Y.; Liu, H.; Lin, Y.; Li, M.; Nan, C.-W., Improving the

dielectric constants and breakdown strength of polymer composites: effects of the shape of the BaTiO3 nanoinclusions, surface modification and polymer matrix. Journal of Materials Chemistry 2012, 22 (32), 16491-16498. 27.

Liu, S.; Zhai, J., Improving the dielectric constant and energy density of

poly(vinylidene fluoride) composites induced by surface-modified SrTiO3 nanofibers by polyvinylpyrrolidone. Journal of Materials Chemistry A 2015, 3 (4), 1511-1517. 28.

Tang, Y.; Xu, S.; Xie, Y.; Gu, J.; Song, Z.; Gao, F.; Kong, J., Interfacial RAFT

polymerization induced ultra low dielectric loss ceramic/cyanate ester composites. Composites Science and Technology 2016, 124, 10-16. 29.

Yu, K.; Niu, Y.; Zhou, Y.; Bai, Y.; Wang, H., Nanocomposites of Surface-

Modified BaTiO3 Nanoparticles Filled Ferroelectric Polymer with Enhanced Energy Density. Journal of the American Ceramic Society 2013, 96 (8), 2519-2524. 30.

Zhou, W.; Gong, Y.; Tu, L.; Xu, L.; Zhao, W.; Cai, J.; Zhang, Y.; Zhou, A.,

Dielectric

properties

and

thermal

conductivity

of

core-shell

structured

Ni@NiO/poly(vinylidene fluoride) composites. Journal of Alloys and Compounds 2017, 693, 1-8.


Page 27 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


31.

Zhou, W.; Xu, L.; Jiang, L.; Peng, J.; Gong, Y.; Liu, X.; Cai, H.; Wang, G.;

Chen, Q., Towards suppressing loss tangent: Effect of SiO2 coating layer on dielectric properties of core-shell structure flaky Cu reinforced PVDF composites. Journal of Alloys and Compounds 2017, 710, 47-56. 32.

T. C. Choy, Effective Medium Theory: Principles and Applications; Oxford

University Press: New York, 1999 33.

L. An, S. A. Boggs, J. P. Callame, Energy storage in polymer films with high

dielectric constant fillers. IEEE Electr. Insul. Mag.2008, 24, 5–10. 34.

Calame, J. P., Dielectric permittivity simulation of random irregularly shaped

particle composites and approximation using modified dielectric mixing laws. Journal of Applied Physics 2008, 104 (11), 114108. 35.

Bao, Z.; Lovinger, A. J.; Dodabalapur, A., Organic field‐effect transistors with

high mobility based on copper phthalocyanine. Applied Physics Letters 1996, 69 (20), 3066-3068. 36.

Nalwa, H. S.; Dalton, L. R.; Vasudevan, P., Dielectric properties of copper-

phthalocyanine polymer. European Polymer Journal 1985, 21 (11), 943-947. 37.

Zhang, Q. M.; Li, H.; Poh, M.; Xia, F.; Cheng, Z. Y.; Xu, H.; Huang, C., An

all-organic composite actuator material with a high dielectric constant. Nature 2002, 419, 284.



38.

Page 28 of 39

Wang, J.; Guan, F.; Cui, L.; Pan, J.; Wang, Q.; Zhu, L., Achieving high electric

energy storage in a polymer nanocomposite at low filling ratios using a highly polarizable phthalocyanine interphase. Journal of Polymer Science Part B: Polymer Physics 2014, 52 (24), 1669-1680. 39.

Li, Q.; Chen, L.; Gadinski, M. R.; Zhang, S.; Zhang, G.; Li, H. U.; Iagodkine,

E.; Haque, A.; Chen, L.-Q.; Jackson, T. N.; Wang, Q., Flexible high-temperature dielectric materials from polymer nanocomposites. Nature 2015, 523, 576. 40.

Pan, J.; Li, K.; Chuayprakong, S.; Hsu, T.; Wang, Q., High-Temperature Poly

(phthalazinone ether ketone) Thin Films for Dielectric Energy Storage. ACS Applied Materials & Interfaces 2010, 2 (5), 1286-1289; 41.

Cheng, Z.; Lin, M.; Wu, S.; Thakur, Y.; Zhou, Y.; Jeong, D.-Y.; Shen, Q.;

Zhang, Q. M., Aromatic poly(arylene ether urea) with high dipole moment for high thermal stability and high energy density capacitors. Applied Physics Letters 2015, 106 (20), 202902. 42.

Wang, Y.; Huang, X.; Li, T.; Wang, Z.; Li, L.; Guo, X.; Jiang, P., Novel

crosslinkable high-k copolymer dielectrics for high-energy-density capacitors and organic field-effect transistor applications. Journal of Materials Chemistry A 2017, 5 (39), 20737-20746. 43.

Sadeghi, S.; Arjmand, M.; Otero Navas, I.; Zehtab Yazdi, A.; Sundararaj, U.,

Effect of Nanofiller Geometry on Network Formation in Polymeric Nanocomposites:


Page 29 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Comparison of Rheological and Electrical Properties of Multiwalled Carbon Nanotube and Graphene Nanoribbon. Macromolecules 2017, 50 (10), 3954-3967. 44.

Arjmand, M.; Sadeghi, S.; Khajehpour, M.; Sundararaj, U., Carbon

Nanotube/Graphene Nanoribbon/Polyvinylidene Fluoride Hybrid Nanocomposites: Rheological and Dielectric Properties. The Journal of Physical Chemistry C 2017, 121 (1), 169-181.



Page 30 of 39

TOC：


Page 31 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. (a) FT-IR spectra of the as-received BT, BT-OH, BT-CN, and BT-HCuPc. (b) TGA curves of BT, BTCN, BT-CuPc and BT-HCuPc. 74x31mm (300 x 300 DPI)

ACS Paragon Plus Environment


Figure 2. TEM image of the (a) BT, (b) BT-CuPc and (c) BT-HCuPc nanoparticles. 39x10mm (300 x 300 DPI)


Page 32 of 39

Page 33 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. SEM images of BT/PES (a-20vol%, b-30 vol%), BT-CuPc/PES (c-20 vol%, d-30 vol%), BTHCuPc/PES (e-20 vol%, f-30 vol%). 78x37mm (300 x 300 DPI)



Figure 4. Relative permittivity (a, b, c)/ Dielectric loss tangent (d, e, f)/AC conductivity (g, h, i)) of the BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites 123x91mm (300 x 300 DPI)


Page 34 of 39

Page 35 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. Comparison of (a) dielectric constant, (b) dielectric loss, (c) AC conductivity of BT/PES, BTCuPc/PES, BT-HCuPc/PES with varied composition. 43x11mm (300 x 300 DPI)



Figure 6. Breakdown strength of BT/PES, BT-CuPc/PES and BT-HCuPc/PES composites at (a) 25 oC and (b) 150 oC. 49x19mm (300 x 300 DPI)


Page 36 of 39

Page 37 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. Dielectric properties of BT-HCuPc/PES composites at 1 kHz as a function of temperature. 61x25mm (300 x 300 DPI)



Figure 8. D-E loops (a), discharged energy density (b) and discharged-charged efficiency (c) of the BTHCuPc/PES composites under different electric field. 49x14mm (300 x 300 DPI)


Page 38 of 39

Page 39 of 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Scheme 1. The overall fabrication procedure for core-shell structures of (a) hyperbranched modified BTHCuPc, (b) in-situ synthesized BT-CuPc. 338x190mm (96 x 96 DPI)


High-k Polymer Nanocomposites Filled with Hyperbranched

Recommend Documents