Nanodiamond Ternary Hybrids

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Polydopamine Modified Polyaniline/Nanodiamond Ternary Hybrids with Brain Fold-like Surface for Enhanced Dual Band Electromagnetic Absorption Xiangnan Chen, Junxiang Zhou, Yan Zhang, Shibu Zhu, Xin Tian, Fanchen Meng, Liying Cui, Peihong Xue, Ruoxuan Huang, and Juncai Sun ACS Appl. Polym. Mater., Just Accepted Manuscript • DOI: 10.1021/acsapm.8b00127 • Publication Date (Web): 31 Jan 2019 Downloaded from http://pubs.acs.org on February 5, 2019

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ACS Applied Polymer Materials

Polydopamine Modified Polyaniline/Nanodiamond Ternary Hybrids with Brain Fold-like Surface for Enhanced Dual Band Electromagnetic Absorption Xiangnan Chen*,1 Junxiang Zhou, 1 Yan Zhang, 1 Shibu Zhu,2 Xin Tian,3 Fanchen Meng,4 Liying Cui,1 Peihong Xue,1 Ruoxuan Huang1, Juncai Sun1 1 College of Transportation Engineering, Dalian Maritime University, Dalian 116026, China. 2 Xi’an Aerospace Composites Research Institute, Xi’an 710025, China. 3 Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China. 4 Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA KEYWORDS: Polydopamine, Polyaniline, Nanodiamond, Brain fold-like surface, ternary hybrids, interface, dual band electromagnetic absorption

* Corresponding

author: Xiangnan Chen, Email: [email protected] (X. Chen)

ACS Paragon Plus Environment

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ABSTRACT: Polydopamine modified nanodiamond/polyaniline ternary hybrids with brain foldlike surfaces were synthesized through an in situ polymerization. The surface morphology and structure were characterized by X-ray diffraction analysis, scanning and transmission electron microscopy. In the ternary hybrids, the dispersion of nanodiamond was improved. In the meanwhile uniform brain fold-like surface could form after adding certain amount of dopamine. The hybrid interactions were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The hydrogen bonding interactions as well as the π-π hybrid interactions dominate the tannery hybridization, which could introduce more asymmetrical polarization

center

and

interface.

The

optimized

polydopamine

modified

nanodiamond/polyaniline ternary hybrid exhibited obvious dual band enhanced electromagnetic absorption (-24.3 dB, 5.0 GHz and -23.5 dB, 15.9 GHz). The electromagnetic losses result from the surface brain fold-like structure, the well dispersed nanodiamond size-effect, as well as the ternary hybridization. Our finding indicates this material has great potential interests in high performance electromagnetic selective absorption materials covering C band and Ku band.

INTRODUCTION Nowadays, electromagnetic (EM) pollution has become an increasingly serious problem in daily life as well as in the military affairs [1]. The wider use of electronic products and the release of high-voltage EM waves in the industry, transportation, medical equipment and military fields have made EM waves always exist around us and endangering our health. Based on these problems, high-performance EM absorption materials have aroused great research enthusiasm to meet the demand of light weight, broadband, multi-frequency compatibility, and strong absorption [2-5].


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Polyaniline (PANi), as a representative conducting polymer, was often used as dielectric absorption materials for the advantage of light weight, low cost and friendly design

[6-8]

. One of

the common ideas for PANi based EM absorber was introducing more asymmetric interfaces and polarization centers, accompanying special nano-effect by incorporating PANi with low dimensional nanomaterials, such as graphene [11]

and other nano carbon

[12]

[9]

, nanodiamond (ND)

[10]

, carbon nanotubes

. The EM absorption for such materials was high, but always

focused on middle and high frequency (10-18 GHz) with relatively single EM loss mold, accompanied by thermal dissipation. However, exploring light weight, multi-frequency EM absorbers with compatibility covering 2-18 GHz is still challenging. Considering the additional nano effects and interface effects, various kind of nanoparticles have been used to assemble hybrid materials as potential EM absorber

[13-16]

. ND, with high

hardness, good chemical stability, excellent thermal stability and other basic properties of diamond, plus extra nano-effect, were widely used in sensors

[17]

, catalysis

[18]

, lubricant

[19]

and

some other fields [20]. However, due to the high specific surface area like other nanoparticles, the agglomeration of ND could be the biggest obstacle restricting its practical applications

[21]

.

According to our previous work [10], the key factor affecting the EM absorption characteristics of PANi/ND actually lied in the dispersion of ND in the PANi matrix and the relative hybridization interaction. By further improving the dispersion of ND and regulating the hybridization interaction, it is expected to widen the EM absorption band and achieve broadband compatibility. Early studies on dopamine (DA), a well-known neurotransmitter field of medicine and life science

[23-25]

[22]

, mainly focused on the

. Back in 2007, Messersmith proposed a simple and

versatile method for surface modification of materials based on the biomimetic properties of DA [26]

, which realized the surface modification of any shape solid material from metallic materials


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to inorganic nonmetallic materials. With the emergence of polydopamine (PDA) derivatives, DA has become a research hotspot in various interdisciplinary fields

[27-31]

. One of the important

applications of DA is the auxiliary dispersion of nanomaterials. Fei et al.

[28]

developed an

ultrasonic assisted method using DA alkaline solution to improve the dispersion of carbon nanotubes. DA could also be used for the modification of ND

[29]

. Cao et al.

[30]

obtained super

hydrophobic ND for efficient oil/water separation using DA as surface modification agent. Qin et al.

[31]

also used functional groups of DA to improve the compatibility between ND and

polyimide matrix. Notably, DA could play dual roles in the modification of ND, such as auxiliary dispersion and regulating the hybridization. Herein, considering the dual roles of DA in the modification of ND, we come up with an in situ polymerization for synthesizing PDA modified PANi/ND hybrids, called PANi/ND/PDA ternary hybrids, as shown in Figure 1. PANi/ND/PDA ternary hybrids could be obtained along with effectively improved ND dispersion, additional hybridization as well as PDA modified surface. The as-prepared PANi/ND/PDA hybrid exhibited obvious dual band EM absorption.

Figure 1. Schematic illustration of the dispersion of ND and in situ polymerization for synthesizing PANi/ND/PDA hybrids.


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EXPERIMENTAL SECTION Materials Nanodiamond (ND, 5-10 nm) was purchased from XF NANO, Inc., Nanjing, China. Aniline (ANi, Macklin, Inc., Shanghai, China.) was distilled under reduced pressure (35 mmHg, 85 ℃) and stored below 0 ℃ before used. Dopamine hydrochloride (C8H11NO2·HCl, 98%) was purchased from Macklin, Inc., Shanghai, China. And other materials, such as 36% hydrochloric acid (HCl), ammonium peroxydisulfate (APS, (NH4)2S2O8), and ethanol (95%) were all of analytical grade. Preparation of PANi/ND/PDA ternary hybrids The PANi/ND/PDA ternary hybrids were synthesized using an in situ polymerization process. Thus, 12 mg C8H11NO2·HCl and 24 mg ND were added into 100 mL 1N HCl aqueous solution. The mixture was stirred for 30 min under 0-5 ℃. Then, 2 mmol aniline (0.2 mL) was added into the above solution. After 2 h sonication (40 kHz, ultrasonic bath) and mechanical stirring for 2 h under 0-5 ℃，0.456g APS dissolved in 50 mL 1 N HCl was slowly added into the solution with a tight stirring. The polymerization system was kept under 0-5 ℃ for 16 h to finish the reaction. The product was washed using deionized water and ethanol for three times. This product was so called PANi/ND/PDA. Series of PANi/ND/PDA hybrids were obtained by adding different amount of dopamine. The C8H11NO2·HCl amount was set to be 6, 9, 12, 15 mg. The obtained products were called PANi/ND/PDA6, PANi/ND/PDA/9, PANi/ND/PDA12, and PANi/ND/PDA/15, respectively. Characterizations The morphologies were observed on a field emission scanning electron microscopy (FESEM, Sirion 200, FEI) and a transmission electron microscopy (TEM, JEM-2100, JEOL).


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Fourier transform infrared (FTIR) spectra with a resolution of 2 cm-1 were detected on a PerkinElmer Frontier spectrometer. X-ray diffraction (XRD) analyses were carried out using a Rigaku D/MAX-Ultima X-ray diffractometer with a CuKα radiation. X-ray photoelectron spectroscopy (XPS, VG Microtech, ESCA 2000) was used to analysis the hybrid interactions in PANi/ND/PDA. The EM parameters were measured on a vector network analyzer (AV3618, CETC, China). The EM test sample were mixed with wax and prepared as the toroidal shape with outer diameter of 7.0 mm, an inner diameter of 3.04 mm and a thickness below 5 mm. The mass ratios of samples to wax were set to be 3:7. RESULTS AND DISCUSSION SEM and TEM observations were carried out to explore the influence of PDA on the morphologies of the PANi/ND hybrids. As shown in Figure 2 (a) and (b), the ND used in this work was of 5-10 nm diameter, while the PANi could form short fiber structure without ND. When adding ND during the polymerization of ANi, the PANi/ND hybrid presented spiny spherical composite structure [Figure 2 (c)]. It is obvious in Figure 2 d that the morphologies of PANi/ND exhibited distinguishable changes after introducing PDA into the polymerization reaction. The PANi/ND/PDA showed a composite structure with brain fold-like surface. The dispersion of ND was further compared using TEM observation as in Figure (e) and (f). For PANi/ND, there existed some obvious agglomeration of ND as in the red circle marked in Figure 2 (e). While for PANi/ND/PDA, it could be seen that ND dispersed uniformly in PANi and there was hardly any agglomeration of ND [Figure 2 (f)]. More TEM images for well dispersed ND were supplied as supporting information in Figure S1. Considering the same adding amount of ND, the dispersion of ND had significant improvements in PANi/ND/PDA compared to that of PANi/ND. The distance among the adjacent ND dispersed in PANi/PDA was about 10-20 nm


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(See Figure S1), which could make some microchannel under nanoscale. From the morphologies observations, the experimental design was verified. The PDA played a dual role in the system, promoting the dispersion of ND and controlling the surface coating morphologies.

Figure 2. FE-SEM images of (a) ND (b) HCl-PANi (c) PANi/ND and (d) PANi/ND/PDA; FETEM images of (e) PANi/ND (red circle marked the agglomeration of ND) and (f) PANi/ND/PDA; HR-TEM images of (g) PANi/ND (the insert picture was a detailed display for the orientation of PANi) and (h) PANi/ND/PDA.

The aggregation structures of PANi in the hybrids were further studied using HR-TEM characterization as shown in Figure 2 (g) and (h). For PANi/ND, some individual ND particles could be found in the hybrid with diameter about 5-10 nm (interlayer spacing d = 0.213 nm, corresponding to the (111) planes of diamond

[32]

). Thin layer coating could be observed around

the ND particles with an interlayer spacing d = 0.375 nm, in line with the PANi (111) plane

[33]

,

as shown in Figure 2 (g). This phenomenon indicates that the introduction of ND could affect the orientation and ordered structure of PANi, which however, is not obvious in PANi/ND/PDA.


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There only existed some invisible hybrid interface of PANi and ND, see Figure 2 (h). This is possibly because of the isolation effect of DA on ND, which hindered the orientation of PANi along ND and might introduce additional ternary hybrid interface.

Figure 3. XRD patterns of the PANi/ND/PDA, PANi/ND, HCl-PANi, and the inset is the XRD patterns of ND.

The XRD patterns of PANi, PANi/ND and PANi/ND/PDA were shown in Figure 3. The characteristic peaks at 2θ = 8.9, 14.2, 20.3, 25.2° were attributed to the ordered arrangement of PANi chains

[33]

. These peaks remained almost unchanged in the three samples, which revealed

that the introduction of ND and PDA only affected the nano-interface between PANi and ND (shown in Figure 3), but did not influence the whole orientation and doping degree of PANi. Besides, a sharp peak at 2θ = 43.8° was observed in the XRD patterns of PANi/ND corresponding to the ND (111) plane (d = 0.210 nm)

[32]

. For PANi/ND/PDA, this peak became

flatter than that of PANi/ND, which was due to the disorganization of ND alone the (111) plane, possibly resulted from the better dispersion of ND and the surface coating and modification of PDA on ND.


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Figure 4. The FTIR spectra of the PANi/ND/PDA, PANi/ND, HCl-PANi and ND.

The ternary hybrid interactions in PANi/ND/PDA were investigated by FTIR spectra, as shown in Figure 4. It could be seen that the ND surface was rich in oxygen-containing groups. For ND, the bands at about 3438, 1773, 1635 cm-1 were attributed to the –OH stretching vibrations, C=O stretching vibrations and C=O stretching vibrations for carboxyl groups, respectively[34]. Compared to the spectrum of ND, in the spectra of PANi/ND and PANi/ND/PDA, the bands at 1773, 1635 cm-1 almost disappeared, illustrating that there existed hybrid interactions on the C=O groups in ND. In addition, there were two distinguishable differences between the spectra of PANi/ND and PANi/ND/PDA. On the one hand, the band at 1484 cm-1, attributed to the C=C stretching vibrations of the benzene rings

[35]

, had an 9 cm-1

blue shift to 1493 cm-1 in PANi/ND/PDA compared to that of PANi, which was not observed in PANi/ND. On the other hand, comparing to the spectra of PANi, the bands at 1128 cm-1, attributed to the Q=N stretching vibrations [36], took a 3 cm-1 blue shift in PANi/ND/PDA, while it had a 4 cm-1 red shift in PANi/ND. These two differences revealed that the hybrid interactions had been altered in PANi/ND/PDA compared to that of PANi/ND. For PANi/ND/PDA, new type


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of ternary hybrid might be formed between Q=N, C=C groups in PANi, C=O groups in ND and –OH, -NH2 groups, benzene ring in PDA. The two blue shifts in PANi/ND/PDA should be caused by the π-π stacking between the benzene ring of PANi and PDA, which could make the bonding interactions of PANi become more confined and stable and further hinder the vibration of the corresponding groups. The multiple hybrid interactions might be the driving force for the formation of brain-like convolutions on the surface, as there was no obvious solvent evaporation in the polymerization process [37].

Figure 5. (a) XPS wide scan of PANi/ND/PDA and PANi/ND; the XPS spectra (C1s) of (b) PANi/ND (c) PANi/ND/PDA; the XPS spectra (N1s) of (d) PANi/ND (e) PANi/ND/PDA; (f) the schematic diagram for ternary hybrid interactions in PANi/ND/PDA.

The XPS spectra were shown in Figure 5, which could give a detailed evidence for the ternary hybrid interactions. The content of O in PANi/ND/PDA increased from 15.8% to 20.2% compared with PANi/ND, which further confirmed the existence of PDA in the hybrids, as


10

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shown in Figure 5 (a). From Figure 5 (b) and (c) we could see, four typical peaks for C1s could be found in the C1s spectra of PANi/ND, thus there were four different type of C atoms in the hybrid, C-C (284.6 eV), C-N (285.8 eV), C-O (287.0 eV) and C=O (289.0 eV) [38]. Obviously, in the C1s spectra of PANi/ND/PDA, the C-O peak shifted to 286.7 eV, while the C=O peak to 288.4 eV. Combined with the FTIR results, this was possibly because of the H bond interactions took place between PDA and the oxidant containing groups of ND, which changed the chemical environment of C=O and C-O groups. The N1s spectra for these two hybrids were shown in Figure 5 (d) and (e). For PANi/ND, the 399.7 and 401.8 eV peaks represented the –NH and – NH2+ groups

[39]

. A typical peak at 402.2 eV could be found in the N1s spectra of

PANi/ND/PDA, which was due to the existence of –RNH2 groups in PDA

[40]

. Besides, the –

NH2+ peak showed an obvious shift to 401.0 eV. This illustrated the existence of strong H bond interactions between the –NH2+ groups in PANi chains and the N atoms in PDA. According to the FTIR and XPS results, the schematic diagram for ternary hybrid interactions in PANi/ND/PDA were given in Figure 5 (f). The main hybrid interactions were proved to be the H bond interactions between PDA and C=O, C-O groups in ND, the π-π hybrid interaction between the benzene ring of PDA and PANi, and the H bond interactions between PDA and the NH2+ groups in PANi, which could bring in more asymmetrical polarization center and interface into the hybrid. Series of PANi/ND/PDA hybrids were obtained by adding different amount of DA. The SEM images were shown in Figure 6. It could be seen clearly that the surface morphology gradually changed with increasing the DA dosage. When the DA amount increased up to 12 mg, the morphology of the hybrid became more homogeneous, showing a uniform brain fold-like surface. When the DA amount was 6 and 9 mg, PDA was not enough to form complete coating.


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Therefore, the surface morphologies were not so homogeneous, and there were some partial agglomerated structures, as shown in Figure 6 (a) and (b), which confirmed PDA had played multiple roles in the hybrids: improving the dispersion of ND, forming the ternary hybrid interactions, as well as importantly regulating and constructing the nano-ravine surface.

Figure 6. SEM images of (a) PANi/ND/PDA6 (b) PANi/ND/PDA9 (c) PANi/ND/PDA12 (d) PANi/ND/PDA15.

The EM parameters of HCl-PANi, ND and PANi/ND/PDA hybrids (with different amount of PDA) were measured, including the complex permittivity real part (ε′), permittivity imaginary part (ε′′), permeability real part (μ′) and permeability imaginary part (μ′′), as shown in Figure 7. Among these samples, both the value of ε’ and ε’’ decreased with increasing frequency. The ε′′ of PANi/ND/PDA hybrids showed obvious multiple peaks around 4-6 GHz, 6-8 GHz and 14-18 GHz [see Figure 7 (b)]. It could be inferred that the introduction of PDA-ND into PANi influenced the EM dielectrical response mold of the hybrids. According to the structural discussion, EM dielectrical loss mold for the hybrids could be conductivity loss at lower frequency, interfacial polarization relaxation, dipole polarization relaxation, as well as structural resonance at higher frequency [2, 41].


12

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Figure 7. The measured frequency dependence of (a) real (b) imaginary parts of complex permittivity and (c) real (d) imaginary parts of permeability of ND, HCl-PANi, PANi/ND/PDA6, PANi/ND/PDA9, PANi/ND/PDA12, PANi/ND/PDA15; The inset pictures were the detailed permeability data under 4-10 GHz.

From Figure 7 (c) and (d), both μ′ and μ′′ of PANi/ND/PDA hybrids showed obvious response peaks around 4-8 GHz. In order to explore the magnetic response mechanism, the value of μ′′(𝜇′)−2 𝑓 −1 were calculated as shown in Figure S2. It could be seen that, the value of μ′′(𝜇′)−2 𝑓 −1 were not a constant and kept changing at the frequency of 4-8 GHz, which illustrated that the magnetic loss of the hybrids at 4-8 GHz were basically not from eddy current loss

[42]

. The magnetic loss was mainly due to the exchange resonance and domain wall


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resonance [10, 43], which might result from the well dispersed ND particles and the brain fold-like surface, respectively. Microchannel under nanoscale might bring in special EM wave reflection and interference effect

[44]

. While for 8-18 GHz, the value of μ′′(𝜇′)−2 𝑓 −1 stayed as a constant,

which revealed the possible existence of eddy current loss at higher frequency.

Figure 8. (a) The calculated dielectrical dissipation factor and (b) The calculated magnetic dissipation

factor

of

PANi/ND/PDA6,

PANi/ND/PDA9,

PANi/ND/PDA12

and

PANi/ND/PDA15.

The dielectrical dissipation factor tan⁡(ε′′⁄ε′) and the magnetic dissipation factor tan⁡(μ′′⁄μ′) could reveal the EM loss form and response frequency of the materials

[45]

. It could be noticed

from Figure 8 that both the magnetic loss tangent and dielectric loss tangent values were at a similar numerical level. Multiple dielectric response peaks appeared at 4-6 GHz, 7-9 GHz and 10-18 GHz for the PANi/ND/PDA hybrids (See Figure 8 (a)). According to the structural discussion, there existed π-π interaction between PANi and PDA. This could bring about more πelectron orbital overlap and larger charge carrier delocalization, which made electronic charge easier to generate directional transfer for additional conductivity loss under the action of EM wave. As discussed above, the surface effect of ND could also synergistically promote the carrier


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transport in the hybrids. Thus, the conductivity loss at low frequency could be improved. Besides, ternary hybrid interface structure and the dual hydrogen bonding interaction could introduce more dipole and interfacial polarization center, which make the induced polarization in the hybrids lag behind the change of the external EM field at relative high frequency. This could actually lead to more conversion of incident EM wave energy into relaxation loss

[46]

. Thirdly,

the well dispersed ND particles and ternary hybrid network could bring about high frequency structural resonance. Interestingly, there existed obvious sharp magnetic response peaks at about 4-6 GHz and 14-18 GHz, as shown in Figure 8 (b). The effective dispersion of ND and special brain fold-like surface could lead to the exchange resonance and domain wall resonance introducing low frequency magnetic losses (4-6 GHz). This could result from the EM reflection and interference microchannel formed by the brain fold-like surface and individual ND under nanoscale. And the response peaks at 14-18 GHz were believed to be caused by eddy current loss, according to the results of Figure S2. In addition, it could be noticed from Figure 8 that the intensity of dielectrical and magnetic response peaks at 4-6 GHz changed a lot with different amount of PDA. The additive amount of PDA could affect the surface structure and hybridization, thus regulate the EM response and loss. It was concluded that the introduction of PDA could simultaneously enhance the dielectrical and magnetic loss, which might resulted in better impedance matching.


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Figure 9. Three dimensional maps for calculated RL values of (a) ND (b) HCl-PANi (c) PANi/ND/PDA6 (d) PANi/ND/PDA9 (e) PANi/ND/PDA12 and (f) PANi/ND/PDA15.

The reflection loss (RL) values could be calculated using the measured EM parameters, according to the transmission line model [47], 𝑍 −𝑍

RL(dB) = 20 log |𝑍𝑖𝑛+𝑍0 | 𝑖𝑛

(1)

0

2𝜋𝑓𝑑

𝑍𝑖𝑛 = 𝑍0 √𝜇𝑟 ⁄𝜀𝑟 𝑡𝑎𝑛ℎ [𝑗 (

𝑐

) √𝜇𝑟 𝜀𝑟 ]

(2)

where 𝑍𝑖𝑛 represented the characteristic impedance, Z0 was the free space impedance，ε𝑟 and μ𝑟 were the measured and calculated relative complex permittivity and permeability. f was the frequency of EM, and d, c were the thickness of samples and the velocity of microwave in free space, respectively. Figure 9 depicted the calculated RL values of the samples with different thickness of 0-5 mm. Compared with HCl-PANi, ND [See Figure 9 (a) and (b)], PANi/ND/PDA hybrids showed


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improvements in microwave absorption. All the four samples of PANi/ND/PDA hybrids with different PDA amount presented obvious microwave absorption covering dual band, around 4-6 GHz (C band) and 14-18 GHz (Ku band). For PANi/ND/PDA6, the optimal absorption peaks were (-10.4 dB, 5.4 GHz) and (-9.6 dB, 18.0 GHz). With increasing the amount of PDA, the hybrids showed better microwave absorption properties. For PANi/ND/PDA9, the optimal absorption peaks were (-14.0 dB, 5.3 GHz) and (-15.0 dB, 16.6 GHz). PANi/ND/PDA12 with uniform nano ravine exhibited the most excellent EM loss among these samples. The minimum RL values reached (-15.7 dB, 5.3GHz) in C band and (-26.5 dB, 18.0 GHz) in Ku band. The brain fold-like structures were believed to have some synergistic enhancement effect on the interface polarization. While, for PANi/ND/PDA15, the optimal absorption peaks were (-11.2 dB, 5.3 GHz) and (-10.5 dB, 18.0 GHz). The decrease of the RL value for PANi/ND/PDA15 was probably because of that the over coating of DA prevented EM waves from entering and further hindered and reduced the EM loss. Detailed optimizations of the thickness for PANi/ND/PDA12 were given in Figure S3. Notably, PANi/ND/PDA12 showed obvious dual band absorption. The optimized thickness of hybrid was 5.6 mm with strongest dual band microwave loss (-24.3 dB, 5.0 GHz and -23.5 dB, 15.9 GHz). This result presented distinguishing differences in the EM loss band compared with our previous work

[10]

, in which it was found that PANi/ND hybrids

without brain fold-like surface only showed single EM loss band (-28.9 dB, 12 GHz) corresponding to HN-CO group introduced medium frequency polarization relaxation loss. These differences further revealed that the introduction of DA brought about a new multiple EM absorption mechanism. This material could be a potential high quality EM selective shielding materials covering C band (nowadays mobile phones network signal band) and Ku band (modern


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satellite communication band). In addition, it could provide design ideas for multi band compatible EM absorbing materials.

Figure 10. Schematics of EM loss mechanism for PANi/ND/PDA ternary hybrids.

The EM loss mechanism was further described in Figure 10. The key point was about the regulation of the EM loss band range, which could be explained by the multiple interface edge reflecting and scattering, ternary hybrid polarization loss and dual resonance. At first, the enhanced dual band loss benefitted from the special brain fold-like surface. This structure could increase the microwave absorption path resulting in multiple reflection loss. Meanwhile, the well dispersion of ND with nano-revine surface was proved to introduce low frequency exchange resonance and domain wall resonance due to nanoscale EM effect. Secondly, the ternary hybridization remarkably enhanced the dielectrical and eddy current loss of the materials. The dual H bonding among PANi, PDA as well as ND could introduce more dipole and asymmetric interface into the hybrid, which further make more interfacial polarization and dipole polarization relaxation at low or middle frequency. On the other hand, the π-π interaction between the benzene ring of PANi and PDA could promote the carriers transportation, which further simultaneously improve low frequency conductive loss and high frequency eddy current


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loss. Lastly, at high frequency, the EM loss mold for PANi/ND/PDA should include additional structural resonance caused by the ternary network. CONCLUSION Brain fold-like PDA modified PANi/ND ternary hybrids were synthesized using an in situ polymerization. Taking advantage of the dual roles of DA, the dispersion of ND in PANi matrix was effectively improved. At the same time, the complex hybridization based on hydrogen bonding and π-π interaction were realized. It was proved that the introduction of PDA could significantly change the surface morphology, and simultaneously enhance the dielectrical and magnetic loss. The optimized PANi/ND/PDA hybrid showed obvious dual band absorption (24.3 dB, 5.0 GHz and -23.5 dB, 15.9 GHz). The EM loss characteristics mainly benefitted from multiple reflection absorption of brain fold-like surface, exchange resonance and domain wall resonance caused by the well dispersed ND nano-effect, as well as multiple polarizations and interfacial relaxation resulted from the ternary hybridization. This work could give insights into the design of multi-band compatible and selective EM absorbing materials.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publication website at DOI: ***. Detailed FE-TEM images of PANi/ND/PDA showing the well dispersion of ND (The dispersed distance between each ND was about 10-20 nm), the calculated μ′′(𝜇′)−2 𝑓 −1 values


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for PANi/ND/PDA hybrids, and detailed calculated RL for PANi/ND/PDA12 with optimizations of the thickness are provided as supporting information.

AUTHOR INFORMATION * Corresponding author: Xiangnan Chen, Email: [email protected] ACKNOWLEDGMENT This work was financially supported by the Fundamental Research Funds for Central University of China (No. 3132016065, No. 3132018111, and No. 3132018119), the Young Scientists Fund of the National Natural Science Foundation of China (No. 83118009) REFERENCES [1] Cao, M.-S.; Han, C.; Wang, X.-X.; Zhang, M.; Zhang, Y.-L.; Shu, J.-C.; Yang, H.-J.; Fang, X.-Y.; Yuan, J. Graphene Nanohybrids: Excellent Electromagnetic Properties for the Absorbing and Shielding of Electromagnetic Waves. J. Mater. Chem. C. 2018, 6, 4586-4602. [2] Ye, F.; Song, Q.; Zhang, Z.-C.; Li, W.; Zhang, S.-Y.; Yin, X.-W.; Zhou, Y.-Z.; Tao, H.-W.; Liu, Y.-S.; Cheng, L.-F.; Zhang, L.-T.; Li, H.-J. Direct Growth of Edge-rich Graphene with Tunable Dielectric Properties in Porous Si3N4 Ceramic for Broadband High-performance Microwave Absorption. Adv. Funct. Mater. 2018, 28, 1707205-1707214. [3] Jian, X.; Xiao, X.-Y.; Deng, L.-J.; Tian, W.; Wang, X.; Mahmood, N.; Dou S.-X. Herterstructured Nanorings of Fe-Fe3O4@C Hybrid with Enhanced Microwave Absorption Performance. ACS Appl. Mater. Interfaces 2018, 10, 11, 9369-9378.


20

Page 21 of 37 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


[4] Li, Q.-Q.; Liu, J.-W.; Zhao, Y.-H.; Zhao, X.-B.; You, W.-B.; Li, X.; Che R.-C. “Matryoshka doll”-Like CeO2 Microspheres with Hierarchical Structure to Achieve Significantly Enhanced

Microwave

Absorption

Performance.

ACS

Appl.

Mater.

Interfaces

2018, 10, 32, 27540-27547. [5] Meng, F.-B.; Wang, H.-G.; Huang, F.; Guo, Y.-F.; Wang, Z.-Y.; Hui, D.; Zhou, Z.-W. Graphene-based Microwave Absorbing Composites: A Review and Prospective. Composites Part B 2018, 137, 260-277. [6] Wang, Y.; Du, Y. -C.; Xu, P.; Qiang, R.; Han, X.-J. Recent Advances in Conjugated Polymer-Based Microwave Absorbing Materials. Polymer 2017, 9, 29-57. [7] Liu, J.; Duan, Y.-P.; Song, L.-L.; Zhang, X.-F. Constructing Sandwich-like Polyaniline/Graphene Oxide Composites with Tunable Conjugation Length Toward Enhanced Microwave Absorption. Org. Electron. 2018, 63, 175-183. [8] Li, X.; Yu, L.-J.; Yu, L.-M.; Dong, Y.-B.; Gao, Q.; Yang, Q.-X.; Yang, W.-T.; Zhu, Y.-F.; Fu, Y.-Q. Chiral Polyaniline with Superhelical Structures for Enhancement in Microwave Absorption. Chem. Eng. J. 2018, 352, 745-755. [9] Chen, X.-N.; Meng, F.-C.; Zhou, Z.-W.; Tian, X.; Shan, L.-M.; Zhu, S.-B.; Xu, X.-L.; Jiang, M.; Wang, L.; Hui, D. One-step Synthesis of Graphene/Polyaniline Hybrids by In situ Intercalation Polymerization and Their Electromagnetic Properties. Nanoscale. 2014, 6, 81408148.


21


Page 22 of 37

[10] Chen, X.-N.; Tian, X.; Zhou, Z.-W.; Jiang, M.; Lu, J.; Wang, Y.; Wang, L. Effective Improvement in Microwave Absorption by Uniform Dispersion of Nanodiamond in Polyaniline through in-situ Polymerization. Appl. Phys. Lett. 2015, 106, 233103. [11] Tian, X.; Meng, F.-B.; Meng, F.-C.; Chen, X.-N.; Guo, Y.-F.; Wang, Y.; Zhu, W.-J.; Zhou, Z.-W. Synergistic Enhancement of Microwave Absorption Using Hybridized Polyaniline@helical CNTs with Dual Chirality. ACS Appl. Mater. Interfaces 2017, 9, 18, 1571115718. [12] Yu, L.-J.; Zhu, Y.-F.; Fu, Y.-Q. Waxberry-like Carbon@polyaniline Microspheres with High-performance Microwave Absorption. Appl. Surf. Sci. 2018, 427, 451-457. [13] Li, S.-P.; Huang, Y.; Zhang, N.; Zong, M.; Liu, P.-B. Synthesis of Polypyrrole Decorated FeCo@SiO2 as A High-performance Electromagnetic Absorption Material. J. Alloy. Compd. 2019, 774, 532-539. [14] Zhang, N.; Huang, Y.; Zong, M.; Ding, X.; Li, S.-P.; Wang, M.-Y. Synthesis of ZnS Quantum Dots and CoFe2O4 Nanoparticles Co-loaded with Graphene Nanosheets as An Efficient Broad Band EM Wave Absorber. Chem. Eng. J. 2017, 308, 214-221. [15] Zhang, N.; Huang, Y.; Wang, M.-Y. 3D Ferromagnetic Graphene Nanocomposites with ZnO Nanorods and Fe3O4 Nanoparticles Co-decorated for Efficient Electromagnetic Wave Absorption. Composites Part B 2018, 136, 135-142. [16] Zhang, N.; Huang, Y.; Wang, M.-Y.; Liu, X.-D.; Zong, M. Design and Microwave Absorption Properties of Thistle-like CoNi Enveloped in Dielectric Ag Decorated Graphene Composites. J. Colloid. Interf. Sci. 2019, 534, 110-121.


22

Page 23 of 37 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


[17] Zhang, T.; Liu, G.-Q.; Leong, W.-H.; Liu, C.-F.; Kwok, M.-H.; Ngai, T.; Liu, R.-B.; Li, Q. Hybrid Nanodiamond Quantum Sensors Enabled by Volume Phase Transitions of Hydrogels. Nat. Commun. 2018, 9, 3188-3196. [18] Su, D.-S.; Perathoner, S.; Centi, G. Nanocarbons for the Development of Advanced Catalysts. Chem. Rev. 2013, 113, 5782-5816. [19] Hsin, Y.-L.; Chu, H.-Y.; Jeng, Y-R.; Huang, Y.-H.; Wang M.-H.; Chang, C.-K. In situ De-agglomeration and Surface Functionalization of Detonation Nanodiamond with the Polymer Used as An Additive in Lubricant Oil. J. Mater. Chem. 2011, 21, 13213-13222. [20] Mochalin, V.-N.; Shenderova, O.; Ho, D.; Gogotsi, Y. The Properties and Applications of Nanodiamonds. Nat. Nanotechnol. 2012, 7, 11-23. [21] Behler, K.-D.; Stravato, A.; Mochalin, V.; Korneva, G.; Yushin, G.; Gogotsi, Y. Nanodiamond-Polymer Composite Fibers and Coatings. ACS Nano 2009, 3, 363-369. [22] Kalivas, P.-W. Neurotransmitter Regulation of Dopamine Neurons in the Ventral Tegmental Area. Brain Research Reviews, 1993, 18, 75-113. [23] Wise, R.-A. Dopamine, Learning and Motivation. Nat. Rev. Neurosci. 2004, 5, 483-494. [24] Kim, J.-H.; Auerbach, J.-M.; Rodríguez-Gómez, J.-A.; Velasco, I.; Gavin, D.; Lumelsky, N.; Lee, S.-H.; Nguyen, J.; Sánchez-Pernaute, R.; Bankiewicz, K.; McKay, R. Dopamine Neurons Derived from Embryonic Stem Cells Function in An Animal Model of Parkinson’s Disease. Nature 2002, 418, 50-56. [25] Waelti, P.; Dickinson, A.; Schultz, W. Dopamine Responses Comply with Basic Assumptions of Formal Learning Theory. Nature 2001, 412, 43-48.


23


Page 24 of 37

[26] Lee, H.; Dellatore, S.-M.; Miller, W.-M.; Messersmith, P.-B. Mussel-inspired Surface Chemistry for Multifunctional Coatings. Science 2007, 318, 426-430. [27] Liu, Y.-L.; Ai, K.-L.; Lu, L.-H. Polydopamine and its Derivative Materials: Synthesis and Promising

Applications

in

Energy,

Environmental,

and

Biomedical

Fields.

Chem.

Rev. 2014, 114, 5057-5115. [28] Fei, B.; Qian, B.-T.; Yang, Z.-Y.; Wang, R.-H.; Liu, W.-C.; Mak, C.-L.; Xin, J.-H. Coating Carbon Nanotubes by Spontaneous Oxidative Polymerization of Dopamine. Carbon 2008, 46, 1795-1797. [29] Barras, A.; Lyskawa, J.; Szunerits, S.; Woisel, P.; Boukherroub, R. Direct Functionalization of Nanodiamond Particles Using Dopamine Derivatives. Langmuir 2011, 27, 12451-12457. [30] Cao, N.; Yang, B.; Barras, A.; Szunerits, S.; Boukherroub, R. Polyurethane Sponge Functionalized with Superhydrophobic Nanodiamond Particles for Efficient Oil/Water Separation. Chem. Eng. J. 2017, 307, 319-325. [31] Qin, S.-L.; Cui, M.-J.; Qiu, S.-H.; Zhao, H.-C.; Wang, L.-P.; Zhang, A.-F. Dopamine@Nanodiamond as Novel Reinforcing Nanofillers for Polyimide with Enhanced Thermal, Mechanical and Wear Resistance Performance. RSC Adv. 2018, 8, 3694-3704. [32] Qin, L.-C.; Zhou, D.; Kcauss, A.-R.; Gruen. D.-M. TEM Characterization of Nanodiamond Thin Films. Nanostruct. Mater. 1998, 10, 649-660. [33] Tursun, A.; Zhang, X.-G.; Ruxangul, J. Comparative Studies of Solid-state Synthesized Polyaniline Doped with Inorganic Acids. Mater. Chem. Phys. 2005, 90, 367-372.


24

Page 25 of 37 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


[34] Krueger, A.; Lang, D. Functionality is Key: Recent Progress in the Surface Modification of Nanodiamond. Adv. Funct. Mater. 2012, 22, 890-906. [35] Chen, S.-A.; Lee, H.T. Structure and Properties of Poly(acrylic acid)-Doped Polyaniline. Macromolecules. 1995, 28, 2858-2866. [36] Tang, J.; Jing, X.; Wang, B.; Wang, F. Infrared Spectra of Soluble Polyaniline. Synth. Met. 1988, 24, 231-238. [37] Zhu, Y.; Li, J.-M.; Wan, M.-X.; Jiang, L.; Wei, Y. A New Route for the Preparation of Brain-Like Nanostructured Polyaniline. Macromol. Rapid Commun. 2007, 28, 1339-1344. [38] Wang, B.; Luo, B.; Liang, M.-H.; Wang, A.-L.; Wang, J.; Fang, Y.; Chang, Y.-H.; Zhi, L.-J.; Chemical Amination of Graphene Oxides and Their Extraordinary Properties in the Detection of Lead Ions, Nanoscale, 2011, 3, 5059-5066. [39] Yazdi, A.-Z.; Chizari, K.; Jalilov, A.-S.; Tour, J.; Sundararaj, U.; Helical and Dendritic Unzipping of Carbon Nanotubes: A Route to Nitrogen-doped Graphene Nanoribbons, ACS Nano. 2015, 9, 5833-5845. [40] Gao, H.-C.; Sun, Y.-M.; Zhou, J.-J.; Xu, R.; Duan, H.-W. Mussel-Inspired Synthesis of Polydopamine-Functionalized Graphene Hydrogel as Reusable Adsorbents for Water Purification. ACS Appl. Mater. Interfaces 2013, 5, 425-432. [41] Cao, M.-S.; Yang, J.; Song, W.-L.; Zhang, D.-Q.; Wen, B.; Jin, H.-B.; Hou, Z.-L.; Yuan, J. Ferroferric Oxide/Multiwalled Carbon Nanotube vs Polyaniline/Ferroferric Oxide/Multiwalled Carbon Nanotube Multiheterostructures for Highly Effective Microwave Absorption. ACS Appl. Mater. Interfaces 2012, 4, 6949-6956.


25


Page 26 of 37

[42] Lu, M.-M.; Cao, M-S.; Chen, Y.-H.; Cao, W.-Q.; Liu, J.; Shi, H.-L.; Zhang, D.-Q.; Wang, W.-Z.; Yuan, J. Multiscale Assembly of Grape-Like Ferroferric Oxide and Carbon-Nanotubes: A Smart Absorber Prototype Varying Temperature to Tune Intensities. ACS Appl. Mater. Interfaces 2015, 7, 34, 19408-19415. [43] Wang, H.; Dai, Y.-Y.; Gong, W.-J.; Geng, D.-Y.; Ma, S. Broadband Microwave Absorption of CoNi@C Nanocapsules Enhanced by Dual Dielectric Relaxation and Multiple Magnetic Resonances Appl. Phys. Lett. 2013, 102, 223113-223117. [44] Zhang, Y.; Huang, Y.; Zhang, T.-F.; Chang, H.-C.; Xiao, P.-S.; Chen, H.-H.; Huang, Z.Y.; Chen, Y.-S. Broadband and Tunable High-Performance Microwave Absorption of An Ultralight and Highly Compressible Graphene Foam. Adv. Mater. 2015, 27, 12, 2049-2053. [45] Zhang, X.-J.; Wang, G.-S.; Cao, W.-Q.; Wei, Y.-Z.; Liang, J.-F.; Guo, L.; Cao, M.-S. Enhanced Microwave Absorption Property of Reduced Graphene Oxide (RGO)-MnFe2O4 Nanocomposites and Polyvinylidene Fluoride. ACS Appl. Mater. Interfaces 2014, 6, 7471-7478. [46] Kim, S.-S.; Kim, S.-T.; Yoon, Y.-C.; Lee, K.-S. Magnetic, Dielectric, and Microwave Absorbing Properties of Iron Particles Dispersed in Rubber Matrix in Gigahertz Frequencies. J. Appl. Phys. 2005, 97, 10F905. [47] Zhao, B.; Shao, G.; Fan, B.-B.; Zhao, W.-Y.; Xie, Y.-J.; Zhang, R.; Systhesis of Flowerlike CuS Hollow Microspheres Based on Nanoflakes Self-assembly and Their Microwave Absoption Properties. J. Mater. Chem. A. 2015, 3, 10345-10352.


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Figure 1. Schematic illustration of the dispersion of ND and in situ polymerization for synthesizing PANi/ND/PDA hybrids. 177x62mm (600 x 600 DPI)


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Figure 2. FE-SEM images of (a) ND (b) HCl-PANi (c) PANi/ND and (d) PANi/ND/PDA; FE-TEM images of (e) PANi/ND (red circle marked the agglomeration of ND) and (f) PANi/ND/PDA; HR-TEM images of (g) PANi/ND (the insert picture was a detailed display for the orientation of PANi) and (h) PANi/ND/PDA. 177x84mm (300 x 300 DPI)



Figure 3. XRD patterns of the PANi/ND/PDA, PANi/ND, HCl-PANi, and the inset is the XRD patterns of ND. 85x67mm (600 x 600 DPI)


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Figure 4. The FTIR spectra of the PANi/ND/PDA, PANi/ND, HCl-PANi and ND. 84x66mm (600 x 600 DPI)



Figure 5. (a) XPS wide scan of PANi/ND/PDA and PANi/ND; the XPS spectra (C1s) of (b) PANi/ND (c) PANi/ND/PDA; the XPS spectra (N1s) of (d) PANi/ND (e) PANi/ND/PDA; (f) the schematic diagram for ternary hybrid interactions in PANi/ND/PDA. 177x93mm (600 x 600 DPI)


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Figure 6. SEM images of (a) PANi/ND/PDA6 (b) PANi/ND/PDA9 (c) PANi/ND/PDA12 (d) PANi/ND/PDA15. 177x40mm (300 x 300 DPI)



Figure 8. (a) The calculated dielectrical dissipation factor and (b) The calculated magnetic dissipation factor of PANi/ND/PDA6, PANi/ND/PDA9, PANi/ND/PDA12 and PANi/ND/PDA15. 177x66mm (600 x 600 DPI)


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Figure 9. Three dimensional maps for calculated RL values of (a) ND (b) HCl-PANi (c) PANi/ND/PDA6 (d) PANi/ND/PDA9 (e) PANi/ND/PDA12 and (f) PANi/ND/PDA15. 177x97mm (300 x 300 DPI)



Figure 10. Schematics of EM loss mechanism for PANi/ND/PDA ternary hybrids. 177x65mm (600 x 600 DPI)


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Table of Contents 79x20mm (300 x 300 DPI)


Nanodiamond Ternary Hybrids

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