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: yjoo0727@kist.re.kr

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.

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