Enhancement of electroconductivity of polyaniline/graphene oxidenanocomposites through in situ emulsion polymerization

Syed Muhammad Imran • YouNa Kim •

Godlisten N. Shao • Manwar Hussain •

Yong-ho Choa • Hee Taik Kim

Received: 18 July 2013 / Accepted: 9 October 2013

� Springer Science+Business Media New York 2013

Abstract The present study introduces a systematic

approach to disperse graphene oxide (GO) during emulsion

polymerization (EP) of Polyaniline (PANI) to form nano-

composites with improved electrical conductivities. PANI/

GO samples were fabricated by loading different weight

percents (wt%) of GO through modified in situ EP of the

aniline monomer. The polymerization process was carried

out in the presence of a functionalized protonic acid such as

dodecyl benzene sulfonic acid, which acts both as an

emulsifier and protonating agent. The microstructure of

the PANI/GO nanocomposites was studied by scanning

electron microscopy, transmission electron microscopy,

X-ray diffraction, UV–Vis spectrometry, Fourier transform

infrared, differential thermal, and thermogravimetric anal-

yses. The formed nanocomposites exhibited superior mor-

phology and thermal stability. Meanwhile, the electrical

conductivities of the nanocomposite pellets pressed at

different applied pressures were determined using the four-

probe analyzer. It was observed that the addition of GO

was an essential component to improving the thermal

stability and electrical conductivities of the PANI/GO

nanocomposites. The electrical conductivities of the

nanocomposites were considerably enhanced as compared

to those of the individual PANI samples pressed at the

same pressures. An enhanced conductivity of 474 S/m was

observed at 5 wt% GO loading and an applied pressure of 6

t. Therefore, PANI/GO composites with desirable proper-

ties for various semiconductor applications can be obtained

by in situ addition of GO during the polymerization

process.

Introduction

Advancements in semiconductor technologies prompt

many researchers to fabricate superior materials with

desirable properties for that purpose. Predominantly, con-

ductive polymers have gained a lot of attention due to their

unique morphology and structure suitable for different

technological applications. These materials are particularly

used for electronic applications such as sensors, light-

emitting diodes, and solar cells. Recently, Polyaniline

(PANI) has emerged as one of the most promising con-

ducting polymers for industrial applications due to its

desirable electrical, electrochemical, and optical properties,

and excellent environmental and thermal stability [1].

Generally, PANI is solely unique since its electrical

properties can reversibly be controlled by changing the

oxidation state of the main chain and protonation of the

imine nitrogen atoms.

Various nanofillers can be added in PANI matrix to

synthesis nanocomposites in order to gain composites with

superior thermal, electrical, and mechanical properties.

Particularly, a new type of functional nanocomposite based

on graphene oxide (GO)-reinforced PANI has extensively

been studied to produce materials with desired electro-

chemical properties. GO is a potential nanofiller due to its

suitable mechanical, structural, and thermal properties in

comparison with conventional nanofillers [2, 3]. However,

many researchers are carrying out extensive studies to

S. M. Imran � Y. Kim � G. N. Shao � M. Hussain � Y. Choa �H. T. Kim (&)

Department of Fusion Chemical Engineering, College of

Engineering Sciences, Hanyang University, Ansan,

Gyeonggi 426-791, Republic of Korea

e-mail: khtaik@yahoo.com; khtaik@hanyang.ac.kr

G. N. Shao

Department of Chemistry, Mkwawa College, University of Dar

es Salaam, Iringa, United Republic of Tanzania

123

J Mater Sci

DOI 10.1007/s10853-013-7816-5

investigate the structure of GO. Wilson et al. [4] using

TEM imaging and diffraction demonstrated that GO retains

strong crystalline order. Rourke and Thomas et al. [5, 6]

showed that GO produced by the Hummers method is

composed of functionalized graphene sheets decorated by

strongly bound oxidative debris, which acts as a stabilizer

for the GO aqueous suspensions. Therefore, the chemical

stability, easy availability, low cost of precursor (natural

graphite), and the possibility of being produced in large-

scale quantities are the main attributes making GO more

preferable than other types of fillers such as carbon nano-

tubes (CNTs) and carbon nanofibers. It can be an appro-

priate substitute for CNTs and does not require helicity

control. The GO can readily be dispersed in water due to its

strong hydrophilic properties. The tunable polar oxygen-

containing groups on GO make strong interfacial interac-

tions with polar molecules and polymers resulting in

intercalated or exfoliated GO-based polymer nanocom-

posites [7–9]. Moreover, the thermal stability of the

nanocomposites improves to a great extent with the addi-

tion of GO [10–12].

The exfoliated GO possesses a large surface area and

could form stronger interactions with the PANI matrix than

that of tubular CNTs resulting in the superior thermal and

electrical properties [13]. Many researchers [14–16] have

reported that PANI/GO nanocomposites can endorse better

electrochemical capacitance and charge–discharge cyclic

stability than its individual components. During in situ

synthesis of nanocomposites, the aniline is chemically

polymerized in an acidic aqueous medium in the presence

of an oxidant [17]. The obtained polymer is irregular, in

powder form, and often with low degrees of crystallinity

and molecular orientation, which is associated with modest

values of the electrical conductivity of the as-polymerized

polymer [18]. The conductivity of PANI depends on the

ability to transport charge carriers along the polymer

backbone and for the carriers to hop between polymer

chains. Zhang [19] and Xia et al. [20] described that the

conductivity of PANI is a sum of the inter-chain and intra-

chain conductivity. In case of coil-like conformation of

PANI chains, the intra-chain conductivity increases, while

the high crystallinity of PANI will result in the increase of

inter-chain conductivity.

Yu et al. [12] synthesized PANI/Graphite nanocom-

posites by the chemical oxidation method in the presence

of perchloric acid (a very strong acid) to yield nanocom-

posites with modest values of electrical conductivities.

Subsequently, Zhao et al. [13] reported the synthesis of

PANI/GO nanocomposites through in situ polymerization

of aniline using hydrochloric acid. The maximum electrical

conductivity of the nanocomposites was 751 S/m for the

nanocomposites with GO contents [40 wt%. In both cases,

strong acids were used in the polymerization process

leading to the formation of nanocomposites with low

crystallinity.

Herein, we synthesized highly crystalline PANI/GO

nanocomposites by using modified in situ emulsion poly-

merization (EP) of the aniline monomer. Aniline was

polymerized in an emulsion of water and xylene. The

polymerization process for the synthesis of PANI/GO

nanocomposites was carried out in the presence of a

functionalized protonic acid, such as dodecyl benzene

sulfonic acid (DBSA), which acts simultaneously as an

emulsifier and protonating agent for the resulting PANI.

The thermal stability of the nanocomposites with different

GO wt% was also examined. The relationship among

conductivities, GO content, and pressing pressure was

studied by forming pellets of PANI/GO nanocomposites at

different pressing pressures and determining their electrical

conductivities. The electrical conductivities obtained in the

present study were exquisitely compared to those available

in the literature. The effect of using DBSA on the elec-

troconductive properties of the PANI/GO nanocomposites

pressed at different pressures has not been yet reported.

Experimental

Materials

All chemical reagents used in this study were of analytical

laboratory grade, purchased from different sources and

used without any further purification. Graphite, aniline,

DBSA, potassium permanganate (KMnO4), and ammo-

nium peroxydisulfate (APS, (NH4)2S2O8) were procured

from Sigma-Aldrich. Hydrochloric acid (36.46, HCl),

hydrogen peroxide (34.01, H2O2), sulfuric acid (98 %

H2SO4), and acetone were purchased from Dae-Jung

Chemicals, South Korea.

Synthesis

Synthesis of GO

GO was prepared from natural graphite powder by modi-

fying the Hummers and Offeman’s method [21]. In a typ-

ical experiment, 1 g graphite powder was added into

17.5 ml H2SO4 and stirred for 2 h while adding 3 g

KMnO4 gently to maintain the temperature of the solution

at B20 �C under constant stirring. The resulting mixture

was then stirred at 35 �C for 30 min and then at 75 �C for

45 min. 23 ml H2O was added into the solution and heated

at 90 �C for 30 min then 75 ml H2O and 10 ml 30 % H2O2

solution was added to terminate the oxidation. The mixture

was then washed with 5 % HCl aqueous solution repeat-

edly until the pH became neutral. 80 ml water was added

J Mater Sci

123

into the resulting precipitate and sonicated well to obtain

GO. The brown dispersion was centrifuged at 4000 rpm for

2 h to remove any unexfoliated GO.

Synthesis of GO/PANI nanocomposites

For the synthesis of PANI/GO nanocomposites, a solution

containing 2.32 ml of aniline, 12.24 g of DBSA, and

125 ml xylene was prepared in a flask. Another solution of

10 ml DI water, 2.34 g APS, and 1, 2, or 5 wt% of GO was

simultaneously prepared under sonication for 30 min. This

solution was then added into the aniline solution drop-wise

over a 30-min period to avoid overheating. The polymer-

ization reaction was allowed to proceed for 24 h and then

375 ml of acetone was added to stop the reaction with a

subsequent precipitation of the solution to obtain PANI/GO

complex. A dark green powder was recovered by filtration,

and washed three times with 75 ml acetone to remove

impurities such as APS, free DBSA, and unreacted aniline

monomer. Finally, the powder was dried in a vacuum

desiccator at room temperature for 48 h.

Characterization

X-ray diffraction (XRD) measurements were performed

using a Rigaku rotating anode X-ray Diffractometer (D/

MAX-2500/PC, Rigaku, Japan) with a scanning speed of

5�/min from 10� to 60� equipped with a Cu-Ka radiation

source (k = 0.15418 nm) at an accelerating voltage of

50 kV and current of 100 mA. The UV–Vis spectra were

recorded using an Optizen 2120 (Perkin Elmer Lambda

35UV, South Korea) spectrophotometer. Fourier transform

infrared (FTIR) spectroscopic measurements of nanocom-

posite pellets were performed using a Nicolet 6700 with a

diamond probe (Thermo Fisher Scientific, MA) within the

range of 4000 to 500 cm-1.

Morphologies of the samples were studied by High

Resolution transmission electron microscopy (HRTEM,

JEM-2100F, JEOL, Japan) and Scanning electron micros-

copy (SEM, JEOL JSM-6330F, Japan). Thermogravimetric

analysis (TGA, TA Instruments, Q500, USA) of the poly-

mer nanocomposites was performed at a heating rate of

20 �C/min under nitrogen environment. Electrical con-

ductivities of the nanocomposite pellets were measured at

room temperature using a collinear 4 probe apparatus

(CMT-SR2000N, Chang Min Co., Ltd., South Korea) with

typical probe spacing s *1 mm. In this method, current is

supplied via a pair of current leads. The voltage drop across

the impedance is measured by a separate pair of leads.

Thus, the voltage drop in the current-carrying wires is

prevented from being added to the actual value. An average

value was reported from three measurements. The pellets

were prepared by compressing nanocomposites into a press

(Auto M-NE, H 3981, CARVER, USA) for 2 min with a

diameter of 10 mm and thickness of 3–4 mm under pres-

sure of 2, 4, and 6 t.

Results and discussion

Even though the EP of aniline using DBSA or other

emulsifiers has been extensively reported [1, 18, 22–24], in

our present study we attempt to modify the technique by

introducing GO as a dopant to improve the properties of the

resulting nanocomposites. It was previously reported [12,

13, 25, 26] that the synthesis of PANI requires strong acids

such as HCl and HOCl4 since the PANI morphology and

the path of polymerization are greatly influenced by the

acidic conditions [27]. Nevertheless, in situ polymerization

using DBSA as both an emulsifier and protonating agent is

more beneficial in precluding the use of strong acids. Under

this systematic synthetic approach, homogeneous disper-

sion of GO in PANI to form nanocomposites with superior

properties (high crystallinity, high electrical conductivity,

and better thermal stability) can exquisitely be attained.

Figure 1 shows the SEM images of GO, PANI, and GO/

PANI nanocomposites. Figure 1a shows that the GO

exhibited wrinkled and layered stacking with the lateral size

up to several micrometers [28], whereas the rod-like struc-

tures of PANI can be observed in Fig. 1b. Figure 1c–e shows

the images of GO/PANI nanocomposites with 1, 2, and 5

wt% GO, respectively. It can be noticed that the morphology

of PANI/GO nanocomposites is significantly different from

that of PANI and GO. PANI/GO nanocomposites exhibited

multiple shapes, mainly flakes along with some fibrillar

morphology. This change in the morphology of PANI

structure with the addition of GO is consistent with the

findings of Yu et al. [12]. Aniline monomer gets absorbed on

the surface of GO flakes and as the polymerization reactions

proceed on the surface of GO flakes, the resulting nano-

composites display a flaky structure. The GO is well dis-

persed in PANI matrix in the case of nanocomposites. The

morphologies of GO, PANI, and PANI/GO nanocomposites

were further compared with HRTEM analysis.

Figure 2 shows the HRTEM images of GO, PANI, and

PANI/GO nanocomposites. The morphology of pure PANI

synthesized by EP indicates the formation of tube-like

structures (Fig. 2b). However, the images of PANI/GO

with 1, 2, and 5 wt% GO presented in Fig. 2c–e reveal

morphologies different from those of pure PANI. This

might be due to the fact that the polymerization reactions

were carried out in the presence of GO sheets. It is note-

worthy that GO is uniformly distributed in the PANI and

no GO agglomerates can be seen. Uniform dispersion of

GO in PANI matrix helps to obtain improved thermal and

electrical properties for the resulting nanocomposites.

J Mater Sci

123

The XRD patterns of the GO and PANI/GO nanocom-

posites are presented in Fig 3. GO shows a characteristic

peak at 2h = 11�, corresponding to the interlayer spacing

of 0.803 nm between GO sheets. For the PANI/GO nano-

composites, no obvious GO peak can be seen in the results.

In the case of PANI/GO (1 wt%) nanocomposite, the peak

for GO is completely missing which reveals that the layers

of GO are completely exfoliated. This exfoliation of GO

helps to align the PANI chains and enhances the crystal-

linity, which is why PANi/GO exhibits high crystallinity as

compared to the other nanocomposites [13, 29]. In the case

of PANI and PANI/GO nanocomposites, the crystalline

peaks appear at 2h = 17.4�, 18.5�, 23.2�, 25.1�, 26.1�, and

30.3�. Intense peaks at 18.5� and 25.1� corresponding to (0

2 0) and (2 0 0) crystal planes are the characteristic peaks

for PANI [10]. Other sharp peaks are attributed to the

branches of DBSA, which act concurrently as a surfactant

and protonating agent for the resulting PANI [1]. The XRD

results confirmed the formation of nanocomposites, and the

sharp peaks indicate that the resulting PANI and its

nanocomposites had high crystallinity.

Figure 4 shows the FTIR spectra of GO, PANI, and

PANI/GO nanocomposites synthesized through this pro-

cess. The GO showed absorption bands at 1740, 1270,

1082, and 3230 cm-1 indicating the presence of carboxyl

(–COOH), epoxy, carbonyl ([C=O), and hydroxyl (–OH)

groups, respectively. The peak at 1620 cm-1 is associated

with the vibration of the absorbed water molecules and

may also be due to the skeletal vibration of the unoxidized

graphitic domain [13, 30]. For PANI, the absorption band

at 1580 cm-1 is characteristic of the imine ([C=N–) group

stretching in the quinoid units [29]. This peak is shifted to

Fig. 1 SEM images of a GO; b PANI and GO/PANI composites with GO concentration of c 1 wt%, d 2 wt%, and e 5 wt%

Fig. 2 TEM images of a GO; b PANI and GO/PANI composites with GO concentration of c 1 wt%, d 2 wt%, and e 5 wt%

J Mater Sci

123

1395 cm-1 in PANI/GO nanocomposites indicating that

the carboxyl group of GO was linked to the nitrogen of the

PANI backbone during polymerization to form cross-

linked nanocomposites [13].

The UV–Vis spectra of GO, PANI, and PANI/GO

nanocomposites are displayed in Fig. 5. The absorption

peak at 226 nm in the GO sample is attributable to the

p–p* electronic transition of the aromatic carbon–carbon

(–C–C–) bonds[30]. PANI and PANI/GO nanocomposites

revealed four different characteristic absorption bands at

254, 361, 460, and 700–800 nm. The absorption bands at

460 and 700–800 nm in the pure PANI spectrum are

sharper. The absorption band at 254 nm corresponds to the

excitation of p–p* transition in the benzenoid rings of

DBSA and the excitation of benzenoid segments in the

PANI [1]. The band at 361 nm represents the p–p* electron

transition in benzenoid rings [28]. The bands at 460 and

700–800 nm belong to the acid-doped state and the polaron

formation in polyaniline, respectively. The band at 460 nm

verifies the increase in the doping level of PANI [31].

TGA and derivative TGA (DTG) curves of GO, PANI,

and PANI/GO nanocomposites are shown in Figs. 6 and 7,

respectively. The initial weight loss of the GO, PANI, and

PANI/GO nanocomposites at around 130 �C is due to

evaporation of water and moisture present in the samples.

The weight loss for GO between 150 and 350 �C of about

30 % is attributed to the removal of the oxygen-containing

groups (hydroxyl (–OH) and carboxyl (–COOH)) [10].

Notable weight loss in the PANI sample between 150 and

600 �C is assigned to the thermal decomposition of bound

DBSA and PANI matrix [1]. The derivative thermogravi-

metric peak temperature (Tp) corresponding to the maxi-

mum weight loss increases with increasing GO loadings.

The Tp value for PANI is 333 �C, which is relatively

shifted to 346, 344, and 340 �C for samples with 1, 2, and 5

wt% GO content, respectively. The PANI with 1 wt% GO

nanocomposite showed the highest thermal degradation

temperature, which might be due to the homogeneous

dispersion of GO throughout the PANI matrix as well as

strong interfacial interactions between GO and the PANI

matrix through p–p* and hydrogen-bonding interactions.

The most probable hydrogen-bonding interaction is formed

between the amine group (–NH–) of PANI as a proton

donor and surface hydroxyl groups (–OH) of GO as proton

acceptor. However, the nanocomposites with 2 and 5 wt%

GO show a degradation temperature slightly lower than

that of the sample with 1 wt% GO loading, which could be

due to the reduced interaction between the PANI and GO at

higher GO contents [10].

Figure 8 shows the electrical conductivities of PANI and

PANI/GO nanocomposite pellets with different GO con-

tents. It can clearly be seen that the electrical conductivity of

the PANI/GO nanocomposite pellets increased significantly

with increasing GO contents and applied pressure. Even

though the pellets pressed by 2 t show a slight increase, a

remarkable increase can be observed in the samples pressed

by 4 and 6 t. These findings are consistent with those reported

by Zhang [19], signifying that increasing the pressing pres-

sure eliminates voids or entrapped air inside the pellets, and

also the fillers inside the polymer matrix come close to each

other to form conductive paths, which reduces the resistance

of the PANI/GO nanocomposites. This phenomenon is dis-

cussed in detail by Hussain et al. [32]. At 2 t of pressing

pressure, the conductivity of the nanocomposites does not

increase sharply because the considerable removal of voids

from the pellets usually takes place at higher compression

pressures [33]. Table 1 summarizes the electrical conduc-

tivities of the PANI nanocomposites reported by different

researchers.

Various studies [1, 19, 34] have substantially reported

PANI blended with different materials to increase its

electrical conductivity. Han et al. [1] used reverse micelle

polymerization to synthesize DBSA-doped PANI nano-

particles with different doping ratios, and a maximum

conductivity of 74 S/m was reported. Meanwhile, Zhang

10 20 30 40 50 60

(e)

(d)

(c)

(b)

Inte

nsit

y (a

.u.)

2Theta degree

(a)

Fig. 3 XRD Patterns of (a) GO; (b) PANI and GO/PANI composites

with GO concentration of (c) 1 wt%, (d) 2 wt%, and (e) 5 wt%

4000 3000 2000 1000

80

100

120

140

160

180 (e)

(d)

(c)

Tra

nsm

itta

nce

(a.u

)

Wavenumber (cm-1)

(a)

(b)

Fig. 4 FTIR spectra of (a) GO; (b) PANI and GO/PANI composites

with GO concentration of (c) 1 wt%, (d) 2 wt%, and (e) 5 wt%

J Mater Sci

123

[19] found that the electrical conductivity of PANI can be

increased to 750 S/m in the presence of p-toluene sulfonic

acid (TSA) as a dopant. However, the electrical properties

of PANI nanocomposites depend not only upon the dopants

but also on the structure of the nanocomposite (powder,

fiber, film etc.), synthesis method, particle size, and

architecture of the constituents comprising the nanocom-

posites [11, 25, 35]. Lu et al. [25] designed and synthesized

a hierarchical film with coaxial PANI/CNT sandwiched

between graphene sheets. The electrical conductivities of

these samples were 70, 680, and 150 S/m for PANI, PANI/

CNT, and PANI/GN, respectively. Particularly, the elec-

trical conductivities of PANI/GO and PANI/GO/CNT were

10 and 410 S/m, respectively. It is obvious that the con-

ductivity of PANI/GO was lower than that of pure PANI

implying that the morphology of the nanocomposites has a

profound effect on the electrical conductivity of the

materials. In the present study, the highest notable elec-

trical conductivity (474 S/m) was achieved in the sample

with 5 wt% GO pressed by 6 t at room temperature. This

appreciable improvement is attributable to the uniform

distribution of GO in PANI and the high crystalline

structure of as-prepared PANI/GO nanocomposites as was

confirmed by the XRD results. Moreover, Zhao et al. [13]

determined the electrical conductivities of PANI/GO

nanocomposites pressed by 10 t at elevated temperatures

(50, 70, and 90 �C), and the sample with 5 wt% GO con-

tent displayed 400 S/m. It is noteworthy that PANI/GO

nanocomposites of the present study demonstrated higher

conductivity (at room temperature and low pressing pres-

sure) than has previously been reported.

Abs

orba

nce

(a.u

)

Wavelength (nm)

GO

200 300 400 500 600 700 800 200 300 400 500 600 700 800

(d)

(c)

(b)

Abo

srba

nce

(a.u

)

Wavelength (nm)

(a)

Fig. 5 UV–Vis absorption spectra of GO, (a) PANI and GO/PANI composites with GO concentration of (b) 1 wt%, (c) 2 wt%, and (d) 5 wt%

0 200 400 600 800 1000

20

40

60

80

100

(e)

(d)

Wei

ght

(%)

Temperature (oC)

(a)

(c)

(b)

Fig. 6 TGA analysis of (a) GO; (b) PANI and GO/PANI composites

with GO concentration of (c) 1 wt%, (d) 2 wt%, and (e) 5 wt%

0 200 400 600 800 1000

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Der

iv. W

eigh

t (%

/o C)

Temperature (oC)

(a)

(b)

(e)(c)

(d)

Fig. 7 DTG analyses of (a) GO; (b) PANI and GO/PANI nanocom-

posites with GO concentration of (c) 1 wt%, (d) 2 wt%, and

(e) 5 wt%

0 2 4 6

100

200

300

400

500

6 ton

4 ton

Con

duct

ivit

y (S

/m)

GO(wt%)

2 ton

Fig. 8 Electrical conductivity of PANI and GO/PANI composites at

different pressures

J Mater Sci

123

The main objective of the present study was to establish

a simple method to disperse GO into PANI to harness the

electrical conductivities of the resulting composites. The

SEM and HRTEM micrographs revealed that GO was well

dispersed indicating that during in situ polymerization of

PANI, dopants such as GO can be introduced to form

composites with improved properties. Moreover, XRD,

UV, and FTIR analysis demonstrated the formation of

composites with high crystallinity and excellent chemical

interaction of PANI and GO, which are substantial attri-

butes for enhancing the electrical properties of materials

[19, 20]. The evaluation of the electrical properties indi-

cated that the conductivities of the composites were criti-

cally dependent on the amount of the dopant, synthesis

method, and pressing pressure during pellet preparation. It

is noteworthy that PANI/GO nanocomposites reported in

the present study exhibited electrical conductivity values

which are superior to those reported in the literature [12,

13, 35]. Therefore, the formation of composites with

improved electrical conductivities by the synthetic

approach introduced by this work is interesting and

recommendable.

Conclusions

We reported the synthesis and characterization of PANI/GO

nanocomposites with GO content ranging from 1 to 5 wt%.

Modified in situ EP route was employed to form PANI/GO

nanocomposites in the absence of strong acids. The structural

and electrical properties were studied under different char-

acterization techniques. TEM results showed the uniform

distribution of PANI on the GO surface, whereas SEM

results showed that GO was well covered with a PANI

matrix. XRD results of the nanocomposites indicated that

both polymer and nanocomposites had high crystallinity due

to doping with DBSA during the polymerization process.

UV–Vis and FTIR results confirmed the existence of inter-

actions between GO and PANI to form nanocomposites.

TGA results clearly indicated that the GO contents were

essential for improving the thermal stability and electrical

properties of PANI. Maximum conductivity (474 S/m) was

attained in samples with 5 wt% GO content and a pressing

pressure of 6 tons. This work provides an effective, easy,

cheap, and reproducible method to synthesize PANI/GO

nanocomposites with desirable properties suitable for vari-

ous semiconductor applications.

Acknowledgements This work was supported by the Korea Insti-

tute of Energy Technology Evaluation and Planning (KETEP) from

the Ministry of Trade, Industry and Energy of the Republic of Korea

through the Human Resources Development Program (Grant No.

20124030200130).

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Table 1 Comparison of the electrical conductivities of PANI-based composites obtained at different conditions

Report Sample

name

Pressing

pressure (t)

Measurement

temperature (�C)

GO

(wt%)

Conductivity

(S/m)

Zhao et al. [13] PANI/GO 10 90 5 400

Zhao et al. [13] PANI/GO 10 90 40 751

Yu et al. [12] PANI/G – 25 50 420

Lu et al. [25] PANI/GO – 25 – 100

Zhang et al. [19] PANI/TSA 0.56 25 – 750

Han et al. [1] PANI/DBSA – 25 – 74

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