Supplementary Information
Effect of Sorted, Homogeneous Electronic Grade Single-Walled Carbon Nanotube on the Electromagnetic Shielding Effectiveness
Ilhwan Yu,a Jaehyoung Ko,a Tea-Wook Kim,b Dong Su Lee,a Nam Dong Kim,a Sukang
Bae,a Seoung-Ki Lee,a Jaewon Choi,c Sang Seok Lee,a Yongho Jooa*
aInstitute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), 92 Chudong-ro, Bongdong-eup, Wanju-gun, Jeonbuk, 55324, Republic of KoreabDepartment of Flexible and Printable Electronics, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeonbuk, 54896, Republic of Korea cDepartment of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju-si, Gyeongnam, 52828, Republic of Korea
*Corresponding Author; Email: [email protected]
This PDF file includes:
Materials and Methods
Figure S1
Figure S2
Figure S3
Figure S4
Table S1
Table S2
Materials and Methods
1. Density gradient centrifugation of SWCNTs
Single-walled carbon nanotubes (SWCNTs) were processed from arc-discharge (Arc)
SWCNT powders (Nanolab, Inc, Waltham, MA). We adopted the method to sort metallic (m-)
and semiconducting (s-) SWCNT from Arnold et al. called density gradient centrifugation
(DGU).[1] We used the two co-surfactant systems (sodium cholate : sodium dodecyl sulfate =
2:3 for m-SWCNT and 1:4 for s-SWCNT). For the preparation of sorted nanotube, we
sonicated ~ 20 mg of Arc-SWCNT in 20 mL of deionized water (DI water) as the co-
surfactant solution. The total surfactant concentration was 2% (w/v) to determine the specific
density profile of m- and s-SWCNT. The mixtures of Arc-SWCNT and the surfactant were
sonicated with tip-sonicator (Sonics & Materials, Inc. USA) for 10 min at 30% power while
the sample was cooled at 15 °C. Before the DGU, iodixanol was added to the mixture, and
then this solution was injected ~5/6 into a linear, 10 mL concertation gradient. The bottom 3
mL of the centrifuge tube is 52% iodixanol, and the top 10 mL does not contain iodixanol.
The solution was centrifuged at 45000 rpm in a swing bucket rotor for 10 h using
ultracentrifuges (Beckman Coulter Inc. USA).
2. Preparation of polymer wrapped s-SWCNT (PFO-BPy@s-SWCNT)
We adopted the method to extract the s-SWCNT from Brady et al. using the polymer
wrapping method. [2] Polymer wrapped s-SWCNT were extracted from Arc SWCNT
powders (Nanolab, Inc, Waltham, MA). A 1:1 weight ratio of SWCNT and PFO-BPy
(American Dye Source) was mixed in 100 ml of toluene. The mixture was ultrasonicated
using an ultrasonic liquid processor (Sonics & Materials, Inc. USA) with 400 W at 30%
amplitude for 10 min. The solution was centrifuged with a swing bucket rotor (Beckman
Coulter Inc. USA) at 100,000g for 10 min. The supernatant was obtained and centrifuged
again at 100,000g for 1 hour and distilled to remove the solvent. The concentrated solution
was dispersed in tetrahydrofuran (THF). The solution is then centrifuged and dispersed with
bath sonication three times with THF to remove the excess PFO-BPy.
3. Formation of films with precisely tunable m-SWCNT content
We adopted the method to fabricate the thin film from Wu et al.[3] For the formation of m-
SWCNT and s-SWCNT thin film, we used vacuum filtration (Millipore) with 0.2 microns
mixed cellulose ester (MCE) membranes. We poured precisely controlled m- and s-SWCNT
solution into the funnel. The solution was filtered through the filtering membrane for 30 min
to remove the solvents. The residual surfactant on the prepared film was subsequently washed
with deionized water. After the formation of the SWCNT thin film on the membrane filter, it
was transferred to the acetone bath to remove the MCE membrane. The remaining nanotube
thin film was acquired with a wire mesh and transferred to a clean acetone bath for the
removal of residual MCE. The freestanding nanotube films were dried under vacuum
overnight.
4. Atomic force microscopy
Diameter, length of individualized m- and s-SWCNT, and the thickness of the thin films were
characterized by an atomic force microscope (AFM, Park Science Corporation) on silicon
wafers using a Si3N4 tip. The AFM images were obtained in non-contact mode. The scan rate
and Z-gain were 0.5 Hz and 6 units, respectively. AFM imaging was obtained in the range of
3-10 μm. The film thickness was measured at multiple spots on identical films. The AFM tip
covered 15 x 15 μm area. While half of the area was covered by SWCNT films, the other half
was of the bare silicon wafer.
5. Imaging
Raman imaging and scanning electron (RISE) microscopy were used to characterize the
SWCNT film. The integration system of confocal Raman microscopy (CRM) and scanning
electron microscopy (SEM) was offered by Zeiss Inc., Germany. The Raman spectra were
carried out using WITEC CRM 200 Raman system. The incident beam source was 532 nm
laser with a laser power of 0.1 mW. SEM images were collected with the LEO-1530 field-
emission scanning electron microscope. UV-VIS-NIR absorption spectra were measured with
an ultraviolet-visible and near infra-red (UV-Vis-NIR) spectrophotometer (Sinco Evolution
201).
6. Conductivity and EMI shielding characterization
The electrical resistivity was measured by a two-probe method using Keithley 2400. SWCNT
films were deposited by drop-casting on the silicon wafer. The thermal deposition of Au (50
nm) at the pressure of 1 x 10-6 bar was used to create the bottom contact electrodes on the
silicon substrate. The channel length and the width of the device were 100 µm and 1 mm,
respectively.
The electromagnetic interference (EMI) shielding effectiveness (SH EF) was collected using
Agilent Keysight 8720C network analyzer. WR-90 rectangular waveguide was used with a 2-
port network analyzer in the X-band frequency range of 8-12 GHz and 12-19 GHz,
respectively. The maximum range of system analyzer was 80 dB. The calibration procedure
of the equipment was carried out using shot, open, and load offset in both ports. To fit the
films onto the waveguide holder, the SWCNT films were cut into 26 x 13 mm2 dimension and
mounted on the sample holder (23 x 10 mm2). The holder was fixed with screws before the
measurement. The S parameters such as S11, S12, S21, S22 were analyzed by vector network
analyzer through the wave guard method. The reflectance and absorbance attenuation (SE r
and SEa) were characterized by the S parameter according to the equation as follows
r=|S11|2 (1)
t=|S21|2, (2)
a = 1 – r – t , (3)
SEr(dB)=−10 log(1−R) , SEa(dB)=−10 log(t /(1−r )), (4)
SEt(dB)=10 log(P1
P t)=SEr+SEa (5)
where a, r, and t are the absorption, reflection, and transmission coefficient, respectively. SEa
is the shielding effectiveness of absorption, SEr is the shielding effectiveness of reflection,
and SEt is the total shielding effectiveness. P1 is the incident power, and Pt is the transmitted
power.
Figure S1. Electromagnetic interference (EMI) shielding effectiveness (SH EF) of s-SWCNT film (99% semiconducting) in the frequency range of 12-19 GHz.
Figure S2. Plot for the length distribution of (A) m-SWCNTs and (B) s-SWCNTs characterized by AFM. SWCNT was spin-coated on the silicon substrate using toluene at 2000 rpm. The length of the SWCNTs was characterized by the Nanoscope software.
Table S1. Dimensional properties of sorted m-SWCNT and s-SWCNT by DGU and the polymer wrapped s-SWCNT (PFO-BPy@s-SWCNT), characterized by atomic force microscopy.
m-SWCNT s-SWCNT PFO-BPy@s-SWCNTNanotube type Arc discharge Arc discharge Arc dischargeDiameter Range
1.2 – 1.7 nm 1.2 – 1.7 nm 1.2 – 1.7 nm
Mean Diameter 1.4 nm 1.4 nm 1.4 nmLength Range 100 nm - 3 µm 100 nm - 3 µm 500 nm - 4 µmMean Length 0.5 µm 0.9 µm 1.6 µm
Figure S3. XPS spectra of (A) C1s peak and (B) N1s peak from s-SWCNT thin film processed by DGU and the PFO-BPy@s-SWCNT.
Figure S4. EMI SH EF of PFO-BPy@s-SWCNT thin film, PFO-BPy@s-SWCNT thin film with further annealing at 400 °C, and control PFO-BPy@s-SWCNT thin-film without rinsing with THF over the solution process.
Table S2 Literature lists of EMI shielding performance.
Type Filler Matrix Content(wt%)
Thickness(cm)
EMI SE (dB)
SSE (dB cm3g-1)
SSE/t(dB cm2g-1)
Ref
Graphene Graphene PS 7 0.25 45.1 173 692 [4]Graphene PEDOT 25 0.08 70 67.3 841.2 [5]Graphene PEI 10 0.23 12.8 44 191.3 [6]Graphene PS 30 0.20 29 64.4 322 [7]Graphene PI 16 0.08 21 937 11712.5 [8]Graphene PMMA 5 0.4 19 24 60 [9]Graphene - Bulk 0.03 25.2 420 14000 [10]Graphene PDMS 0.8 0.1 19.98 333 3330 [11]Graphene-Fe3O4
- Bulk 0.03 24 31 1033.3 [12]
Graphene-Fe3O4
PEI 10 0.25 18 44 176 [13]
Carbon Nanotube
MWCNT PC 20 0.21 39 34.5 164.3 [14]MWCNT ABS 15 0.11 50 47.6 432.7 [15]
MWCNT PS 15 0.2 30 57 285 [16]MWCNT WPU 76.2 0.1 21.1 33 330 [17]SWCNT PS 7 0.12 18.5 541 4508.3 [18]CNT-Sponge
- Bulk 0.24 22 1100 4583.3 [19]
Carbon Materials
CB ABS 15 0.11 20 20.9 190 [15]CB EPDM 37.5 0.2 18 30.3 151.5 [20]Carbon PN
resin- 0.2 51.2 341 1705 [21]
Carbon foam
- Bulk 0.2 40 241 1205 [22]
Metal Copper - Bulk 0.31 90 10 32.2 [23]Stainless-Steel
- Bulk 0.4 89 11 27.5 [23]
Ni fiber PES Bulk 0.285 58 31 108.7 [23]Ni filaments
PES Bulk 0.285 87 47 164.9 [23]
Al foil - Bulk 0.0008 66 24.4 30500 [24]Cu foil - Bulk 0.001 70 7.8 7800 [24]Mxene - Bulk 0.0011 68 28.4 25818 [24]Mxene SA Bulk 0.0008 57 24.6 30750 [24]CuNi - Bulk 0.15 25 104 693.3 [25]CuNi-CNT - Bulk 0.15 54.6 237 1580 [25]Ag nanowire
PI 4.5 0.5 35 1208 2416 [26]
Ag mesh Bulk 0.0001 20 100 1×106 [27]Ag nanowire
Carbon 67 0.3 70.1 18350.8 61200 [28]
Ag nanowire
WPU 28.6 0.23 64 14226180
[29]
Stainless-Steel
PP 1.1 0.31 48 75 241.9 [30]
Mxene - Bulk 0.0006 32 82 136666 [31]Mxene - Bulk 0.0018 50 125 69444 [31]Mxene - Bulk 0.0060 70 318 53000 [31]
This work
SWCNT - Bulk 0.00015 35 20.6 137333SWCNT - Bulk 0.00015 39 23.0 153333
The density of SWCNT was 1.7 g cm-3.
References
[1] M.S. Arnold, A.A. Green, J.F. Hulvat, S.I. Stupp, M.C. Hersam, Sorting carbon nanotubes by electronic structure using density differentiation, Nat. Nanotechnol. 1(1) (2006) 60-65.
[2] G.J. Brady, A.J. Way, N.S. Safron, H.T. Evensen, P. Gopalan, M.S. Arnold, Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs, Sci. Adv. 2(9) (2016) e1601240.
[3] Z. Wu, Z. Chen, X. Du, J.M. Logan, J. Sippel, M. Nikolou, K. Kamaras, J.R. Reynolds, D.B. Tanner, A.F.J.S. Hebard, Transparent, conductive carbon nanotube films, 305(5688) (2004) 1273-1276.
[4] D.X. Yan, H. Pang, B. Li, R. Vajtai, L. Xu, P.G. Ren, J.H. Wang, Z.M. Li, Structured reduced graphene oxide/polymer composites for ultra‐efficient electromagnetic interference shielding, Adv. Funct. Mater. 25(4) (2015) 559-566.
[5] N. Agnihotri, K. Chakrabarti, A. De, Highly efficient electromagnetic interference shielding using graphite nanoplatelet/poly (3, 4-ethylenedioxythiophene)–poly (styrenesulfonate) composites with enhanced thermal conductivity, RSC Adv. 5(54) (2015) 43765-43771.
[6] J. Ling, W. Zhai, W. Feng, B. Shen, J. Zhang, W.g. Zheng, Facile preparation of lightweight microcellular polyetherimide/graphene composite foams for electromagnetic interference shielding, ACS Appl. Mater. Interfaces 5(7) (2013) 2677-2684.
[7] D.-X. Yan, P.-G. Ren, H. Pang, Q. Fu, M.-B. Yang, Z.-M. Li, Efficient electromagnetic interference shielding of lightweight graphene/polystyrene composite, J. Mater. Chem. 22(36) (2012) 18772-18774.
[8] Y. Li, X. Pei, B. Shen, W. Zhai, L. Zhang, W. Zheng, Polyimide/graphene composite foam sheets with ultrahigh thermostability for electromagnetic interference shielding, RSC Adv. 5(31) (2015) 24342-24351.
[9] H.-B. Zhang, Q. Yan, W.-G. Zheng, Z. He, Z.-Z. Yu, Tough graphene− polymer microcellular foams for electromagnetic interference shielding, ACS Appl. Mater. Interfaces 3(3) (2011) 918-924.
[10] B. Shen, Y. Li, D. Yi, W. Zhai, X. Wei, W. Zheng, Microcellular graphene foam for improved broadband electromagnetic interference shielding, Carbon 102 (2016) 154-160.
[11] Z. Chen, C. Xu, C. Ma, W. Ren, H.M. Cheng, Lightweight and flexible graphene foam composites for high‐performance electromagnetic interference shielding, Adv. Mater. 25(9) (2013) 1296-1300.
[12] W.-L. Song, X.-T. Guan, L.-Z. Fan, W.-Q. Cao, C.-Y. Wang, Q.-L. Zhao, M.-S. Cao, Magnetic and conductive graphene papers toward thin layers of effective electromagnetic shielding, J. Mater. Chem. A 3(5) (2015) 2097-2107.
[13] B. Shen, W. Zhai, M. Tao, J. Ling, W. Zheng, Lightweight, multifunctional polyetherimide/graphene@ Fe3O4 composite foams for shielding of electromagnetic pollution, ACS Appl. Mater. Interfaces 5(21) (2013) 11383-11391.
[14] S. Pande, A. Chaudhary, D. Patel, B.P. Singh, R.B. Mathur, Mechanical and electrical properties of multiwall carbon nanotube/polycarbonate composites for electrostatic discharge and electromagnetic interference shielding applications, RSC Adv. 4(27) (2014) 13839-13849.
[15] M.H. Al-Saleh, W.H. Saadeh, U. Sundararaj, EMI shielding effectiveness of carbon based nanostructured polymeric materials: a comparative study, Carbon 60 (2013) 146-156.
[16] M. Arjmand, T. Apperley, M. Okoniewski, U. Sundararaj, Comparative study of electromagnetic interference shielding properties of injection molded versus compression molded multi-walled carbon nanotube/polystyrene composites, Carbon 50(14) (2012) 5126-5134.
[17] Z. Zeng, H. Jin, M. Chen, W. Li, L. Zhou, Z. Zhang, Lightweight and anisotropic porous MWCNT/WPU composites for ultrahigh performance electromagnetic interference shielding, Adv. Funct. Mater. 26(2) (2016) 303-310.
[18] Y. Yang, M.C. Gupta, K.L. Dudley, R.W. Lawrence, Novel carbon nanotube− polystyrene foam composites for electromagnetic interference shielding, Nano Lett. 5(11) (2005) 2131-2134.
[19] M. Crespo, M. González, A.L. Elías, L. Pulickal Rajukumar, J. Baselga, M. Terrones, J. Pozuelo, Ultra‐light carbon nanotube sponge as an efficient electromagnetic shielding material in the GHz
range, Phys. Status Solidi RRL 8(8) (2014) 698-704.[20] P. Ghosh, A. Chakrabarti, Conducting carbon black filled EPDM vulcanizates: assessment of
dependence of physical and mechanical properties and conducting character on variation of filler loading, Eur. Polym. J. 36(5) (2000) 1043-1054.
[21] L. Zhang, M. Liu, S. Roy, E.K. Chu, K.Y. See, X. Hu, Phthalonitrile-based carbon foam with high specific mechanical strength and superior electromagnetic interference shielding performance, ACS Appl. Mater. Interfaces 8(11) (2016) 7422-7430.
[22] F. Moglie, D. Micheli, S. Laurenzi, M. Marchetti, V.M. Primiani, Electromagnetic shielding performance of carbon foams, Carbon 50(5) (2012) 1972-1980.
[23] X. Shui, D. Chung, Nickel filament polymer-matrix composites with low surface impedance and high electromagnetic interference shielding effectiveness, J. Electron. Mater. 26(8) (1997) 928-934.
[24] F. Shahzad, M. Alhabeb, C.B. Hatter, B. Anasori, S.M. Hong, C.M. Koo, Y. Gogotsi, Electromagnetic interference shielding with 2D transition metal carbides (MXenes), Science 353(6304) (2016) 1137-1140.
[25] K. Ji, H. Zhao, J. Zhang, J. Chen, Z. Dai, Fabrication and electromagnetic interference shielding performance of open-cell foam of a Cu–Ni alloy integrated with CNTs, Appl. Surf. Sci. 311 (2014) 351-356.
[26] J. Ma, K. Wang, M. Zhan, A comparative study of structure and electromagnetic interference shielding performance for silver nanostructure hybrid polyimide foams, RSC Adv. 5(80) (2015) 65283-65296.
[27] S. Lin, H. Wang, F. Wu, Q. Wang, X. Bai, D. Zu, J. Song, D. Wang, Z. Liu, Z. Li, N. Tao, K. Huang, M. Lei, B. Li, H. Wu, Room-temperature production of silver-nanofiber film for large-area, transparent and flexible surface electromagnetic interference shielding, npj Flexible Electron. 3(1) (2019).
[28] Y.-J. Wan, P.-L. Zhu, S.-H. Yu, R. Sun, C.-P. Wong, W.-H. Liao, Anticorrosive, Ultralight, and Flexible Carbon-Wrapped Metallic Nanowire Hybrid Sponges for Highly Efficient Electromagnetic Interference Shielding, Small 14(27) (2018) 1800534.
[29] Y. Wu, Z. Wang, X. Liu, X. Shen, Q. Zheng, Q. Xue, J.-K. Kim, Ultralight Graphene Foam/Conductive Polymer Composites for Exceptional Electromagnetic Interference Shielding, ACS Appl. Mater. Interfaces 9(10) (2017) 9059-9069.
[30] A. Ameli, M. Nofar, S. Wang, C.B. Park, Lightweight polypropylene/stainless-steel fiber composite foams with low percolation for efficient electromagnetic interference shielding, ACS Appl. Mater. Interfaces 6(14) (2014) 11091-11100.
[31] J. Liu, H.B. Zhang, R. Sun, Y. Liu, Z. Liu, A. Zhou, Z.Z. Yu, Hydrophobic, flexible, and lightweight MXene foams for high‐performance electromagnetic‐interference shielding, Adv. Mater. 29(38) (2017) 1702367.