polyvinyl alcohol blend composites with enhanced dielectric properties for portable and flexible electronics

Accepted Manuscript Graphene oxide reinforced poly (4-styrenesulfonic acid)/polyvinyl alcohol blend composites with enhanced dielectric properties for portable and flexible electronics Kalim Deshmukh, M. Basheer Ahamed, Kishor Kumar Sadasivuni, Deepalekshmi Ponnamma, Mariam Al-Ali AlMaadeed, S.K. Khadheer Pasha, Rajendra R. Deshmukh, K. Chidambaram PII:

S0254-0584(16)30797-0

DOI:

10.1016/j.matchemphys.2016.10.044

Reference:

MAC 19252

To appear in:

Materials Chemistry and Physics

Received Date: 15 March 2016 Revised Date:

31 August 2016

Accepted Date: 28 October 2016

Please cite this article as: K. Deshmukh, M.B. Ahamed, K.K. Sadasivuni, D. Ponnamma, M.A.-A. AlMaadeed, S.K. Khadheer Pasha, R.R. Deshmukh, K. Chidambaram, Graphene oxide reinforced poly (4-styrenesulfonic acid)/polyvinyl alcohol blend composites with enhanced dielectric properties for portable and flexible electronics, Materials Chemistry and Physics (2016), doi: 10.1016/ j.matchemphys.2016.10.044. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

1

ACCEPTED MANUSCRIPT

Graphene Oxide Reinforced Poly (4-styrenesulfonic acid)/Polyvinyl alcohol Blend Composites with Enhanced Dielectric Properties for Portable and Flexible Electronics Kalim Deshmukh1*, M. Basheer Ahamed1, Kishor Kumar Sadasivuni2, Deepalekshmi Ponnamma3, Mariam Al-Ali AlMaadeed3, S. K. Khadheer Pasha4, Rajendra R. Deshmukh5, K. Chidambaram4

RI PT

1

Department of Physics, B.S. Abdur Rahman University, Chennai-600048, TN, India. Mechanical and Industrial Engineering Department, Qatar University, P.O. Box 2713, Doha, Qatar. 3 Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha, Qatar 4 Department of Physics, School of Advanced Sciences, VIT University, Vellore - 632014, TN, India. 5 Department of Physics, Institute of Chemical Technology, Matunga, Mumbai-400019, India.

SC

2

M AN U

Corresponding author: KalimDeshmukh* Email: [email protected], Phone: +919500187035 Abstract

In this article, Graphene Oxide (GO) reinforced novel polymer composites comprising of poly (4-styrenesulfonic acid) (PSSA) and polyvinyl alcohol (PVA) blend matrix have been developed using colloidal processing technique. The properties and the

TE D

structure of prepared composites were investigated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), UV-vis spectroscopy (UV), Thermogravimetric analysis (TGA), Polarized optical microscopy (POM), Scanning

EP

electron microscopy (SEM) and Atomic force microscopy (AFM). The FTIR and Raman spectroscopy analysis indicate the strong interfacial interaction between GO and PSSA/PVA blend matrix. The XRD and SEM analysis confirm that GO was fully exfoliated into

AC C

individual graphene sheets and dispersed homogeneously within the polymer matrix. The effective reinforcement of GO into PSSA/PVA blend matrix has resulted in the enhancement of dielectric constant. The dielectric constant has increased from 82.67 (50 Hz, 150oC) for PSSA/PVA (50/50) blend to 297.91 (50 Hz, 150oC) for PSSA/PVA/GO composites with 3 wt % GO loading. The dielectric loss (tan δ) has increased from 1.56 (50 KHz, 140oC) for PSSA/PVA (50/50) blend to 2.64 (50 KHz, 140oC) for PSSA/PVA/GO composites with 3 wt % GO loading. These findings provide a new insight to fabricate flexible, high-k dielectric composite as a promising material for energy storage applications. Key words: PSSA, graphene oxide; energy storage; high-k materials; embedded capacitors

2

ACCEPTED MANUSCRIPT 1.

Introduction Over the last few decades, graphene and its allotropes have aroused significant attention

in both academic and industrial research because of their excellent properties and great application potential. The outstanding physical properties, excellent thermal properties and extraordinary mechanical properties of graphene make it a suitable candidate for widespread

RI PT

applications which include solar cells, lithium ion batteries, catalysis, supercapacitors and EMI shielding [1-6]. The most widely used methods for the synthesis of high quality and defect-free graphene are scotch tape method [6] and chemical vapor deposition (CVD) method [7, 8]. An alternative and cost effective route for the synthesis of graphene is the

SC

exfoliation of graphite or its derivative such as graphene oxide (GO). The advantage of this method is that it is a scalable process and it enables the high yield production of GO which

M AN U

contains sp2 and sp3 hybridized carbons having hydroxyl and epoxy functional groups on its basal plane and carbonyl and carboxyl groups on the edges [9-11]. The oxygen-bearing functional groups render GO hydrophilic and dispersible in water. GO readily exfoliates in water and other protic solvents via hydrogen bonding interactions [12, 13]. Hence, processing of polymer/GO composites is comparatively easier than polymer/graphene composites because of the several oxygen-containing functional groups (epoxy, carbonyl, hydroxyl)

TE D

present on the surface of GO. These functional groups provide compatibility (reinforcement) between polymers and GO leading to the fabrication of various high-performance polymer/GO composites [14-17].

EP

The synthesis of novel composite materials having high dielectric constant and low dielectric loss is highly desirable because of their widespread applications in embedded and multilayer capacitors, gate dielectrics for field effect transistors and energy storage devices

AC C

[18, 19]. A fascinating way of enhancing the dielectric properties of polymers is by dispersing conducting fillers such as metal nanoparticles, carbon nanotubes, carbon fibers, etc. into polymer matrix [20-22]. Polymers filled with conducting fillers possess not only high dielectric constant but also excellent flexibility. However, the dielectric loss of composites with polymer/conductive filler is very high because of the leakage current among the conductive fillers. Recently, Kumar et. al. [23] reported the dielectric properties of pristine GO which exhibited high dielectric constant (∼106) with a low dielectric loss at 1 KHz. In several other studies [24-27], GO has been demonstrated as an excellent filler for the fabrication of polymer composites with high dielectric constant and low dielectric loss for energy storage applications. In a similar study, Polyimide/GO composites were prepared via

3

ACCEPTED MANUSCRIPT in-situ polymerization using NH2 functionalized GO as filler to improve mechanical and dielectric properties [28]. The composites of PVDF incorporated with PVA modified reduced graphene oxide (PVA-RGO) exhibited high values of dielectric constant and low values of dielectric loss than that of PVDF/RGO composites [29]. Liang et. al. reported the simple aqueous solution processing method for the synthesis of PVA/GO composite and evaluated

RI PT

the effect of molecular-level dispersion on the mechanical properties of PVA [30]. Thus, in order to harness the exceptional and extraordinary properties of GO, it is essential to achieve uniform dispersion of GO in the polymer matrix.

PSSA is a polyelectrolyte. It has often been used as a dopant for the polymerization of

SC

conductive polymers. It has excellent film forming and coating capability. PSSA can be added to a polymer matrix having cation exchange properties providing higher capacity and

M AN U

diffusion of ionic species resulted from the large size of the polystyrene sulfonate (PSS-) [31]. Linear or cross-linked PSSA has been used in semi-interpenetrating polymer network (IPN). PSSA has been used as a proton exchange membrane material in polymer electrolyte fuel cells. On the other hand, PVA is a synthetic, non-toxic semi-crystalline polymer having the high dielectric strength and high transparency. PVA also has good optical and mechanical properties and excellent thermal stability. It is usually selected as a cross-linker because of its

TE D

film-forming ability, hydrophilic properties and the high density of reactive chemical functionalities. PSSA has often been blended with PVA to form semi-interpenetrating polymer network through in-situ synthesis [32, 33] or through an impregnation process [34, 35]. These strategies involve the use of intra and intermolecular hydrogen bonding resulting

EP

in a dense structure with the flexible film forming property and good chemical resistance. In this paper, we report the fabrication of novel polymer composites featuring PSSA

AC C

and PVA as a matrix and GO as filler using colloidal processing technique. To the best of our knowledge, there are no published reports on GO reinforced PSSA/PVA blend composites. Herein, for the first time, we are reporting the fabrication of PSSA/PVA/GO composites as a flexible high-k dielectric material which can be suitable for energy storage applications in advanced electronic devices such as embedded capacitors. 2.

Experimental Procedures

2.1. Materials All the chemicals used are of analytical reagent grade. PSSA of molecular weight 75,000 gm/mol was purchased from Sigma-Aldrich, India. PVA of molecular weight 85,000-

4

ACCEPTED MANUSCRIPT 124000 gm/mol and degree of hydrolysis 87-89 % was purchased from Sigma-Aldrich, India. Natural graphite powder used in this study was supplied by Carbotech Engineers, Jaipur, India with a particle size of about 40 µm. Sulfuric acid (H2SO4), potassium permanganate (KMnO4), sodium nitrate (NaNO3) and 30% hydrogen peroxide (H2O2) were purchased from S.D. Fine Chemicals, Mumbai, India and used without further purifications. Double distilled

RI PT

water was used as a solvent for the preparation of PSSA/PVA/GO composites. 2.2. Synthesis of Graphene Oxide

GO was synthesized from natural graphite powder using modified Hummers method

SC

[36]. In a typical synthesis process, 5 g of graphite powder was added with 150 ml of concentrated H2SO4, to which 3 g of NaNO3 was subsequently added and mixed well in a 1000 ml round bottom flask. The mixture was kept in an ice bath for 4 hours with stirring at

M AN U

temperature 5oC and 9 g of KMnO4 was gradually added with constant stirring. To avoid the sudden increase in temperature, the rate of addition was controlled carefully. The ice bath was then removed and the mixture temperature was maintained at 40oC. After stirring for 2 hours until it became a brown paste, 100 ml of deionized water was added for dilution. Finally, the mixture was stirred at 98oC for about 1 hour until the color changed from brown

TE D

to yellow. Subsequently, the mixture was stirred for another 10 minutes and then diluted by adding 600 ml of deionized water. This was followed by addition of 30 ml of H2O2 (30 wt %) to the mixture to reduce residual KMnO4. Finally, the solution was then filtered and washed several times with deionized water and dried further at 60oC for 12 hours to obtain GO

EP

powder with the particle size of about 1-5 µm.

2.3. Synthesis of PSSA/PVA/GO Composites

AC C

Different compositions of PSSA/PVA/GO composite films with GO loadings varying from (0 - 3 wt %) were prepared by the colloidal processing technique. The feed compositions used for the preparation of PSSA/PVA/GO composites are given in Table 1. The desired amount of PVA powder was first dissolved in distilled water at 60oC for 4 hours. GO powder was dispersed separately in water and sonicated for 1 hour. Subsequently, the aqueous dispersion of GO was added to the aqueous PVA solution and stirred continuously for 4 hours followed by the addition of PSSA solution to PVA/GO dispersion. The resulting PSSA/PVA/GO dispersion was stirred vigorously for 8 hours, followed by casting onto a cleaned Teflon petri dish and drying at 60oC for 4 hours. The PSSA/PVA/GO composite films of thickness in the range of 80-100µm were removed from the Teflon petri dish and

5

ACCEPTED MANUSCRIPT used for further study. The protocol for the synthesis of PSSA/PVA/GO composites is given in Fig. 1. The photographs of different compositions of PSSA/PVA/GO composites are shown in Fig. 2, indicating the formation of a homogeneous dispersion of GO into PSSA/PVA blend matrix. It can be seen that the PSSA/PVA blend film (Fig. 2 (a)) is colourless and transparent. However, after the addition of GO the composite film exhibits

RI PT

brown colour and the transparency of PSSA/PVA/GO composite films decrease noticeably when the GO content was further increased up to 3 wt %. A high level of transparency indicates that PSSA/PVA/GO composite films have the excellent potential for display encapsulation. Thus, the transparency to the opacity of the composite film can be controlled

SC

simply by varying the GO content. The possible interaction between PSSA, PVA and GO is presented schematically in Fig. 3.

M AN U

2.4. Characterizations

FTIR spectroscopy of PSSA, PVA, GO and different compositions of PSSA/PVA/GO composite films was carried out using Fourier Transform Infrared Spectrophotometer (Shimadzu, IRAffinity-1, Japan) in the wavenumber range 400 – 4000 cm-1. Raman Spectroscopy of graphite, GO and different compositions of PSSA/PVA/GO

TE D

composite films was carried out using Raman Scattering Spectrometer (LABRAM HR 800) by using a 633 nm laser and a 1 µm spot size. The samples were exposed for 10 s with a laser power of 10 mW at room temperature in backscattering mode. A charge coupled camera was

EP

used to collect the data in the wave number range 1000-3000 cm-1. X-ray diffraction patterns of PSSA/PVA/GO composite films with different compositions were obtained using Bruker AXS D8 focus advanced X-ray diffraction meter

AC C

(Rigaku, Japan, Tokyo). The scans were taken in the 2θ range from 10-90o using Cu Kα radiation of wavelength λ = 1.54060 Å with the scanning speed and step size of 1o/ min and 0.01o respectively.

UV–vis absorption spectra of aqueous colloidal dispersion of PSSA/PVA/GO with

different compositions were obtained in the range of 190–600 nm with a Shimadzu UV2401PC and UV–vis spectrophotometer. Thermal stability of PSSA/PVA/GO composite films with different compositions was evaluated using Mettler Toledo, TGA/STDA851, Thermogravimetric analyzer under N2 atmosphere. Samples were heated up to 800oC at the rate of 10oC/min.

6

ACCEPTED MANUSCRIPT The dispersion state of PSSA/PVA/GO composite films with different compositions was examined using crossed polarizing optical microscope (Olympus BX-53, Singapore) at a magnification of 10 X. The surface morphology of PSSA/PVA/GO composite films with different compositions was examined by scanning electron microscope (Carl Zeiss EVO/18SH, UK).

RI PT

An accelerating voltage of 15 kV was applied to obtain SEM images.

The surface topography of PSSA/PVA/GO composite films with different compositions was studied using atomic force microscopy (Nano Surf Easy Scan2,

small piece of composite film on a glass slide.

SC

Switzerland) in tapping mode. The specimens for AFM study were prepared by sticking a

M AN U

Contact angle (CA) analyses of water droplets on the surfaces of PSSA/PVA/GO composite films were investigated at ambient temperature (25oC) using an apparatus (RameHart 21 AC) equipped with a camera and monitor. Water drops of 5 µl were carefully placed on the composite films using a microsyringe and the contact angles were obtained by taking an average of at least ten readings at left and right sides of the water droplets. The average surface energy was obtained directly from the software during CA measurements and the

TE D

work of adhesion was calculated using the formula given elsewhere [37]. The dielectric properties of different compositions of PSSA/PVA/GO composite films were measured using Wayne Kerr 6500B (Chichester, West Sussex, UK) Precision

EP

Impedance Analyzer. The samples were placed inside a computer controlled variable temperature oven, whose temperature can be programmed as per the need. In the present study, the dielectric properties were investigated in the frequency range from 50 Hz to 20

3.

AC C

MHz and temperature in the range 40-150oC with an accuracy of about + 0.1oC. Results and Discussions

3.1. FTIR spectroscopy

In the present study, the interfacial interaction between PSSA, PVA and GO is characterized by FTIR spectroscopy. The FTIR spectra of PSSA, PVA, PSSA/PVA blend and GO powder is shown in Fig. S1. The FTIR spectrum of PSSA shows a broad peak at 3400 cm-1, attributed to the –SO3H group of PSSA [38]. The presence of the band at 1035 cm-1 in FTIR spectrum of PSSA is attributed to symmetric stretching vibrations of -SO3 group [39]. The band identified at 1175 cm-1 is due to asymmetric stretching vibrations of S=O group

7

ACCEPTED MANUSCRIPT [40]. The wagging vibration of C-H in 1, 4 substituted benzene ring of PSSA at 800 cm-1 was also observed [41]. The FTIR spectrum of PVA shows a broad and strong absorption band at 3000-3700 cm-1, attributed to the symmetrical stretching vibration of -OH group. The band at 2928 cm−1 corresponds to C–H asymmetric stretching vibration of the alkyl group [42]. The band at 1733 cm−1 is attributed to the C=O stretching vibration of vinyl acetate group of

RI PT

PVA. Also, the band at 1640 cm−1 can be assigned to the stretching vibration of C=O group of PVA and the band at 1438 cm−1 corresponds to CH2 bending [43-45]. The band at 1321 cm−1 and 1243 cm−1 correspond to CH2 and C–H wagging vibrations respectively. The band at 1084 cm−1 corresponds to the C–O stretching vibration of an acetyl group and the bands at

SC

916 and 840 cm−1 are attributed to the skeletal vibration of PVA [46, 47]. In the FTIR spectrum of PSSA/PVA blend; the intensity of peaks has reduced when compared to FTIR spectrum of pure polymers. Also, in comparison with the O-H peak of PSSA (3400 cm-1), the

M AN U

O-H peak of PSSA/PVA blend is slightly shifted towards lower wavenumbers, indicating the formation of hydrogen bonding between –SO3H group of PSSA and O-H group of PVA [38]. The FTIR spectrum of GO also shows characteristic peaks. The band at 3441 cm-1 is attributed to the O-H stretching vibration and the band at 2920 cm-1 is assigned to C-H stretching. The band at 1635 cm-1 corresponds to C=C stretching vibrations [48, 49]. The band at 1396 cm-1 can be assigned to C-O stretching vibration of a carboxylic group and the

TE D

band at 1255 cm-1 is attributed to C-O stretching vibrations of an epoxy group. The band at 1026 cm-1 can be ascribed to C-O stretching vibrations of an alkoxy group of GO [48-50]. The FTIR spectra of PSSA/PVA/GO composite films with different compositions is depicted

EP

in Fig. 4(a-f) which shows characteristics FTIR peaks of each component present in the composite. Also, it can be seen that the strong FTIR bands in the range 3000-3500 cm-1 are

AC C

slightly blue-shifted, indicating the establishment of intermolecular hydrogen bonding interactions between the oxygen containing functional groups of GO, O-H group of PVA and the –SO3H group of PSSA. 3.2. Raman Spectroscopy Raman spectroscopy is very powerful, non-invasive characterization technique to distinguish ordered and disordered crystal structures of graphene allotropes. The Raman spectra of natural graphite, GO, and PSSA/PVA/GO composite films are depicted in Fig. 5(ag). The Raman spectrum of pristine natural graphite is given in Fig. 5 (a) which shows a strong G-band at 1585 cm-1 and a weak D band at 1326 cm-1. The G band of graphite is attributed to the first order scattering of the E2g mode and the D band corresponds to the

8

ACCEPTED MANUSCRIPT breathing mode for k- phonon of A1g symmetry [48, 51]. The Raman spectrum of GO is given in Fig. 5 (b) which shows an intense D band at 1365 cm-1 and the G band at 1634 cm-1 with D/G intensity ratio of 0.83. In the Raman spectrum of GO, the G band is broadened and at the same time, the intensity of the D band increases substantially. This could be due to the reduction in the size of the in-plane sp2 hybridized domains because of the oxidation and

RI PT

ultrasonic exfoliation. The Raman spectra of PSSA/PVA/GO composite films with different compositions are shown in Fig. 5 (c-g). It can be seen that the PSSA/PVA/GO composite films show the Raman spectra which are very similar to that of GO with slight shifts in the D and G bands. Such shifts in Raman bands are attributed to the restoration of sp2 hybridized

SC

carbon. Thus, Raman spectroscopy results indicate that there are a good interfacial adhesion and stress transfer between the polymer chains and GO [52], suggesting hydrogen bonding

the –SO3H group of PSSA. 3.3. X-ray Diffraction

M AN U

interaction between the oxygen containing functional groups of GO, O-H group of PVA and

XRD is an effective technique to investigate the interlayer changes and the crystalline properties of synthesized material. XRD technique was employed to study the influence of

TE D

GO loadings on the crystalline properties of PSSA/PVA/GO composite films. The XRD pattern of natural graphite, GO, PSSA, PVA and PSSA/PVA blend is depicted in Fig. S2. Graphite powder showed a strong and sharp diffraction peak at 2θ=26.42o with corresponding interplanar spacing (d) = 0.33 nm which is attributed to its high ordered crystalline structure

EP

corresponding to the hexagonal lattice of (002) plane [53]. The XRD pattern of graphite also shows other small peaks at 2θ=44.12o and 54.35o which corresponds to a hexagonal lattice of (100) and (004) respectively. The XRD spectra of GO shows a single characteristic peak at

AC C

2θ = 11.55o with an interplanar spacing of 0.82 nm, indicating the complete oxidation of graphite. The intercalation of oxygen-containing functional groups in between the graphitic layer causes an increase in the interplanar spacing. This indicates that the oxidation process has disrupted the highly ordered crystalline structure of natural graphite. The XRD results confirm that graphite has been successfully converted to GO. The XRD pattern of pristine PSSA shows two broad humps at 2θ = 30.19° and 2θ = 41.02°, confirming the amorphous nature of PSSA. The XRD pattern of pristine PVA shows a crystalline structure with a distinct peak at 2θ = 19.44° which can be assigned to (101) reflections [46]. The crystalline nature of PVA is attributed to the presence of strong inter and intramolecular hydrogen bonding between different monomer units of PVA [44, 47]. The XRD pattern of PSSA/PVA

9

ACCEPTED MANUSCRIPT blend shows a low-intensity peak at 2θ = 19.25° which belongs to PVA and two broad humps at 2θ = 30.17° and 2θ = 41.06° which belongs to PSSA. Also, the intensity of PVA peak is reduced in the blend which could be due to the interaction between –SO3H group of PSSA and the –OH group of PVA. Thus, XRD pattern of PSSA/PVA blend indicates that both PSSA and PVA are miscible. The XRD patterns of PSSA/PVA/GO composite films with

RI PT

different compositions is depicted in Fig. 6(a-f) which shows a single diffraction peak at 2θ = 19.44° which is attributed to the crystalline peak of neat PVA. The XRD peak of GO was not observed in PSSA/PVA/GO composites which imply that GO sheets were fully exfoliated into individual graphene sheets and dispersed in the polymer matrix at the molecular level.

SC

3.4. UV-Vis spectroscopy

The dispersion stability of GO into polymer matrices is the key in exploring the

M AN U

aqueous synthesis routes for the fabrication of graphene-based polymer composites. In the present study, UV-vis spectroscopy was carried out to observe the Plasmon transitions in PSSA/PVA/GO colloids. Graphene reinforced polymer colloids can exhibit interesting absorption patterns at the wavelengths around 230 nm, 260 nm, and 300 nm. These absorption patterns correspond to π, σ and n electron transition (with different bond energies)

TE D

respectively. Fig. S3 (A) shows the UV-vis absorbance spectra of PVA, PSSA, and GO solution. The UV-vis spectrum of pristine PVA shows a single peak at 200 nm which could be attributed to the presence of unhydrolyzed acetate group of PVA. The UV-vis spectrum of PSSA shows a sharp peak around 228 nm and a small shoulder around 262 nm which is

EP

attributed to the π – π* Plasmons of the benzenoid ring of PSSA. The UV-vis spectrum of GO shows a characteristic UV absorption peak at ~230 nm which is attributed to the π – π* Plasmons of the C = C bond. The UV-vis absorbance spectra of PSSA/PVA/GO colloids with

AC C

different compositions are shown in Fig. S3 (B). The PSSA/PVA/GO colloids show two sharp peaks at 195 nm and at 225 nm in addition to a shoulder peak at 262 nm for all composite samples which indicate the significant interaction between the functional groups of PSSA and PVA and oxygen containing functional groups of GO. 3.5. Thermo gravimetric Analysis Thermogravimetric analysis (TGA) was used to study the thermal stability of PSSA/PVA/GO composite films. The TGA thermograms of PVA and PSSA/PVA blend are shown in Fig. S4 (A). It is apparent from the figure that PVA exhibits three-step degradation. The first step of degradation occurs in the temperature range 70oC- 150oC, which could be

10

ACCEPTED MANUSCRIPT due to the elimination of adsorbed water. The second degradation step occurs in the temperature range 150-400oC which could be attributed to the decomposition of the polymer structure. The final degradation step occurs in the temperature range 400-700oC, which is attributed to the decomposition of the residual carbon. The TGA thermogram of PSSA/PVA blend shows two-step degradation. It is apparent from the figure that PSSA/PVA blend

RI PT

exhibits a very less weight loss in the first step of decomposition which occurs from room temperature to 300oC. The second decomposition step starts above 300oC and it can be seen that the blend samples showed very less weight loss (about 20%) in the temperature range 300oC-700oC, which is very smaller amount when compared to neat PVA (about 50 %). The

SC

higher decomposition temperature for PSSA/PVA blend indicates that PSSA/PVA blend has better thermal stability as compared to neat PVA which could be due to strong interaction between –SO3H group of PSSA and the –OH group of PVA. The TGA thermograms of

M AN U

graphite and GO powders are depicted in Fig. S4 (B). From the figure, it is apparent that graphite powder shows a negligible mass loss from room temperature to 600oC, whereas the GO powder showed decomposition in three steps. The first decomposition step of GO occurs at the temperature slightly below 100oC which is associated with the evaporation of moisture. The second decomposition step occurs in the temperature range 150-250oC which is attributed to the pyrolysis of CO, CO2 and some most labile oxygen-containing functional

TE D

groups. The third decomposition step occurs in the temperature range 250-500oC which is attributed to the decomposition of more stable oxygen-containing functional groups such as COOH and –OH [54]. Thus, the higher decomposition temperature for graphite indicates that

EP

it is thermally more stable than GO. The TGA thermograms of different compositions of PSSA/PVA/GO composites are depicted in Fig. S4 (C). The composites showed three step decomposition behavior. The first decomposition step occurs in the low-temperature range

AC C

50-150oC which is due to evaporation of moisture or adsorbed water [55]. The second decomposition step occurs in the temperature range 150-300oC which could be due to splitting of polymer main chain. The third decomposition step occurs in the temperature range 300-500oC which could be attributed to the decomposition of the polymer backbone [55]. Thus, higher decomposition temperatures were observed for PSSA/PVA/GO composite films which could be due to the excellent dispersion of GO into the polymer matrix and the high aspect ratio of GO. The TGA results indicate that the mobility of the polymer segments and GO at the interfaces is suppressed by the strong hydrogen bonding interactions between them, resulting in the improved thermal stability of composites.

11

ACCEPTED MANUSCRIPT 3.6. Morphological Studies The molecular level dispersion of GO into the polymer matrix is one of the key challenges to be achieved because the properties of graphene-based polymer composites strongly depend on how they are dispersed in solutions. In the present investigation, optical microscopy was employed to study the degree of exfoliation of GO and its reinforcement

RI PT

effect in PSSA/PVA/GO composites on a micrometer scale. Fig. S5 represents optical microscopy images of different compositions of PSSA/PVA/GO composite films. At 50 µm scale resolution, a fairly good distribution of GO in the polymer matrix can be seen which could be due to strong hydrogen bonding interactions between PSSA, PVA and GO and good

SC

miscibility between them. Considering the presence of various hydrophilic groups on the surface of GO, one may expect the homogeneous dispersion of GO in hydrophilic polymer

M AN U

systems such as PSSA and PVA. In addition, GO readily exfoliates in water via hydrogen bonding interactions and forms well-dispersed aqueous colloids [12, 13]. Scanning electron microscopy (SEM) was employed to gain further insight into the dispersion of GO in the polymer matrix. It is important to accomplish uniform dispersion of GO within the polymer matrix and good interfacial adhesion between GO and polymer

TE D

matrix is highly desirable to enhance the performance of polymer/GO composites. The SEM microstructure of different compositions of PSSA/PVA/GO composites is depicted in Fig. 7. It can be seen that the PSSA/PVA/GO composites exhibit typical crumpled morphology which is mainly attributed to the high flexibility and high aspect ratio of GO. It is apparent

EP

that GO was fully exfoliated into individual graphene sheets and most of the graphene sheets are well dispersed in the polymer matrix without any re-stacking. This indicates that there is a

AC C

good interfacial adhesion between GO and polymer matrix. Atomic force microscopy (AFM) in a tapping mode was used to study the distribution

of GO in the PSSA/PVA/GO composites. The two-dimensional topographic images obtained from AFM analysis are given in Fig. 8 and three-dimensional topographic images are given in Fig. S6. It is apparent from the figure that PSSA/PVA/GO composites have an irregular morphology which indicates that the incorporation of GO into PSSA/PVA blend composites has increased the surface roughness. The values of roughness parameters such as mean roughness (Sa) and root mean square roughness (Sq) obtained from AFM images are given in Table 2. It can be seen that the surface of PSSA/PVA blend film was relatively smooth (Sa = 8.71 nm) as compare to the surface of the composite film (Sa = 75.85 nm) with 3 wt % GO

12

ACCEPTED MANUSCRIPT loading. The increase in roughness value of PSSA/PVA/GO composites with different GO loadings indicates that there is a good compatibility between the polymers and the filler. 3.7. Contact Angle Analysis The contact angle analysis gives information about the surface characteristics

RI PT

(hydrophobic, hydrophilic) of polymer composites. The contact angles of water droplets on both PSSA/PVA blend and PSSA/PVA/GO composite films were measured to elucidate the influence of GO loading on surface wettability of composites. It can be seen that the obtained contact angles values (Fig. S7, Table 3) for PSSA/PVA blend and PSSA/PVA/GO composite

SC

films were in the range of 78.15o+ 0.06 -48.70o+ 0.05. Compared to PSSA/PVA blend film, the water contact angle of PSSA/PVA/GO composite films with 0.5 wt % GO loading has decreased from 78.15o+ 0.06 - 48.70o+ 0.05. The decrease in the contact angle value can be

M AN U

due to the presence of the oxygen-containing functional groups (hydroxyl, carboxyl etc.) of GO which leads to the enhanced hydrophilicity of composites [56]. However, with further increase in GO loading (1-3 wt %) the water contact angle of composite films has increased which indicate that the surfaces of composites were rough. These results confirm the AFM results where an increase in the surface roughness was observed. The contact angle values

TE D

were used further to obtain surface energy and work of adhesion of composite films. It can be seen that the surface energy and work of adhesion of PSSA/PVA/GO composite films were increased as compared to PSSA/PVA blend film. The surface energy has increased from 36.64 + 0.04 mJ/m2 for PSSA/PVA blend film to 54.51 + 0.03 mJ/m2 for the composite film

EP

with 0.5 wt % GO loading. With further increase in GO loading (1-3 wt %), the surface energy value has decreased. Similarly, the work of adhesion has increased from 86.71 mJ/m2 for PSSA/PVA blend film to 119.47 mJ/m2 for the composite film with 0.5 wt % GO loading.

AC C

The work of adhesion has decreased with further increase in GO loading (1-3 wt %). Thus, from the results of contact angle analysis, it can be concluded that the incorporation of GO into PSSA/PVA blend matrix has significantly changed the surface characteristics of composite films which could be due to the strong interfacial interaction between the individual constituents of composites. 3.8. Dielectric Properties Novel polymer composites with high dielectric constant and low dielectric loss are highly desirable for a broad range of modern power electronics and electrical systems because of their unique combination of excellent flexibility and tunable dielectric properties

13

ACCEPTED MANUSCRIPT [57, 58]. The development of high-k dielectric composite materials for high-frequency applications requires a thorough understanding of the material’s behavior. In the present study, the dielectric properties of PSSA/PVA/GO composites were investigated in order to check their feasibility for embedded capacitor applications. Fig. 9 (a-g) shows the dielectric constant plots of PSSA/PVA (50/50) blend and different compositions of PSSA/PVA/GO

RI PT

composites, measured in the frequency range 50 Hz to 20 MHz and temperature in the range 40-150oC. It is apparent from the figure that the dielectric constant value is high at the lower frequency and with further increase in frequency, the dielectric constant decreases. Such frequency dependent behavior of dielectric constant is due to the ceasing of different polarizations with the increase in the frequency [59, 60]. The maximum value of dielectric

SC

constant for PSSA/PVA (50/50) blend was ε = 82.67 at 50 Hz and at 150oC. The dielectric constant has increased when GO was added to PSSA/PVA blend. For example; for

M AN U

composites with 0.5 wt % GO loadings the maximum value of dielectric constant was ε = 118.79 at 50 Hz and at 150oC and for composites with 3 wt % GO loading the maximum value of dielectric constant was ε = 297.91 at 50 Hz and at 150oC. Thus, more than 3.5 fold increase in the dielectric constant was observed for PSSA/PVA/GO composites with 3 wt % GO loading as compared to PSSA/PVA blend. Table 4 represents comparative values of

TE D

dielectric constant and dielectric loss tangent observed for PSSA/PVA/GO composites. It can be seen that all the high values of dielectric constant for composites were observed at low frequencies which are attributed to the contribution from space charge polarizations [24, 27, 61]. Also, the flexibility of polymer chain has an influence on the dielectric constant of

EP

composites at low frequency. The magnitude of dielectric constant is greatly affected by the presence of dipoles in the polymer matrix which are highly mobile. Thus, the introduction of

AC C

GO into the polymer matrix has improved the dielectric constant significantly. Dielectric loss tangent (tan δ) is another important dielectric property which is a

measure of energy dissipation resulted from the movement of molecules when an external electric field is applied. Hence, the magnitude of the dielectric loss tangent can be used to evaluate the interfacial adhesion between the polymer matrix and the filler. Fig. 10 (a-g) represents the dielectric loss tangent (tan δ) plots of PSSA/PVA (50/50) blend and different compositions of PSSA/PVA/GO composites. It is apparent from the figure that all the composites have similar dielectric loss behavior, i.e. low dielectric loss tangent values at low frequency. In addition, there exists a broad peak at 50 KHz for PSSA/PVA (50/50) blend and for all the composites samples, which is attributed to β relaxation. The reason for such

14

ACCEPTED MANUSCRIPT relaxation peak in the dielectric loss tangent plots is that the movement of polymer chains was maintained with the change of the external frequency leading to the dipolar loss. The maximum value of dielectric loss tangent for PSSA/PVA (50/50) blend was tan δ=1.56 at 50 KHz and at 140oC. The dielectric loss tangent has increased when GO was added to PSSA/PVA blend. For composites with 0.5 wt % GO loading, the dielectric loss tangent

RI PT

value was tan δ=1.69 at 50 KHz and at 140oC. For example; for composite with 3 wt % GO loading, the dielectric loss tangent value was tan δ=2.64 at 50 KHz and at 140oC. However, the values of dielectric loss are low compared to dielectric constant values of composites, which is highly desirable for the applications of composites in advanced electronic devices

SC

such as embedded capacitors. The comparison of dielectric properties of PSSA/PVA/GO composites and PVA-based composites is given in Table 5. It can be seen that PSSA/PVA/GO composites show very good improvement in the dielectric properties

M AN U

compared to other composites at low filler concentrations. Thus, the improvement in the dielectric properties of PSSA/PVA/GO composites with different compositions is attributed to the strong interfacial adhesion between the constituents of composites. 4.

Conclusions

TE D

In conclusion, GO was produced using a modified Hummers method and subsequently reinforced into PSSA/PVA blend matrix to obtain PSSA/PVA/GO composites using colloidal processing technique. GO sheets were homogeneously dispersed in the polymer matrix and stable dispersions were obtained owing to the presence of the highly

EP

hydrophilic oxygen-containing functional groups of GO. The excellent reinforcement of composites was achieved due to the strong interfacial interaction between PSSA, PVA and GO via hydrogen bonding which was confirmed by FTIR spectroscopy. The XRD results

AC C

clearly indicate that GO was fully exfoliated into individual graphene sheets. The higher decomposition temperatures were observed for PSSA/PVA/GO composites as compared to PSSA/PVA blend indicating the improvement in the thermal stability of composites. The improved thermal stability of composites can be attributed to the excellent dispersion of GO into the polymer matrix and the high aspect ratio of GO. The improved dielectric performance of PSSA/PVA/GO composites is attributed mainly to the homogeneous dispersion of GO in the polymer matrix and the strong interaction between PSSA, PVA, and GO. The PSSA/PVA/GO composites constitute a new type of graphene-based composites to be used as a high dielectric constant material in advanced electronic devices such as embedded capacitors. These findings may aid researchers in the development of novel high

15

ACCEPTED MANUSCRIPT dielectric constant materials featuring graphene or other graphene-based nanofillers as a primary component for full exploitation of their excellent properties. Acknowledgements: One of the authors, Kalim Deshmukh is grateful to the management of B.S. Abdur

RI PT

Rahman University, Chennai, TN, India for providing Junior Research Fellowship (JRF) to carry out this research work. References:

Novoselov, Nat. Mater.6 (2007) 652-655. 2. S. Bai, X. Chen, RSC Advances, 2 (2012) 64-98.

SC

1. F. Schedin, A.K. Geim, S. V. Morozov, E. W. Hill, P. Blake, M. I. Katsnelson, K. S.

M AN U

3. K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, J.H. Ahn, P. Kim, J. Y. Choi, B. H. Hong, Nature, 457 (2009) 706-710.

4. A. K. Geim, Science, 324 (2009) 1530-1534.

5. D. Li, R. B. Kaner, Science, 320 (2008) 1170-1171.

6. K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I.

TE D

V. Grigorieva, A. A. Firsov, Science, 306 (2004) 666-669. 7. A. Dato, V. Radmilovic, Z. Lee, J. Philips, M. Frenklach, Nano Lett., 8 (2008)20122016.

8. A. Reina, X. Jia, J. Ho, D. Nezich, H. Son, V. Bulovic, M.S. Dresselhaus, J. Kong,

EP

Nano Lett.,9 (2009) 30-35.

9. S. Park, R. S. Ruoff, Nat. Nanotechnology, 4 (2009) 217-224.

AC C

10. A. Lerf, H. He, M. Foster, J. Klinowski, J. Phys. Chem B., 102 (1998) 4477-4482. 11. K. K. Sadasivuni, D. Ponnamma, B. Kumar, M Strankowskie, R. Cardinaels, P. Moldenaers, S. Thomas, Y. Grohens, Composite Science and Technology, 104 (2014) 18–25.

12. M. S. Spector, E. Naranjo, S. Chiruvolu, J. A. Zasadzinski, Phy. Rev. Lett., 73 (1994)2867-2870. 13. Z. Xin, M. H. Walid, Z. Yue, K. B. Sanjoy, L. Li, P. Siddharth, W. Shiren,L. W. Brandon, Applied Physics Letters, 102 (2013) 141905. 14. K. K. Sadasivuni, D. Ponnamma, S. Thomas, Y. Grohens, Progress in Polymer Science, 39 (2014) 749–780.

16

ACCEPTED MANUSCRIPT 15. W. Shiren, T. Madhava, Q. Jingjing, T. John, D. Derrick, Macromolecules, 42 (2009) 5251-5255. 16. Q. Jingjing, W. Shiren, J. Appl. Polym. Sci., 119 (2011) 3670-3674. 17. R. Liqiang, Q. Jingjing, W. Shiren, Smart Materials and Structures, 21 (2012) 105032-105037.

Materials Letters, 96 (2013) 109–112. 19. X. Hao, J. Adv. Dielectrics, 3 (2013) 1330001-1330014.

RI PT

18. S. K. Kumar, M. Castro, A. Saiter, L. Delbreilh, J. F. Feller, S. Thomas, Y. Grohens,

20. Q. M. Zhang, H. F. Li, M. Poh, F. Xia, Z. Y. Cheng, H. S. Xu, C. Huang, Nature, 419

SC

(2002) 284-287.

21. Z. M. Dang, Y. H. Lin, C. W. Nan, Adv. Mater., 15 (2003)1625-1629. 22. H. P. Xu, Z. M. Dang, Chem. Phys. Lett., 438 (2007) 196-202.

M AN U

23. Kumar S. K, Suresh. P, Srinath. S, Pradip. P, RSC Adv., 5 (2015) 14768-14779. 24. K. Deshmukh, M. B. Ahamed, R. R. Deshmukh, S. K. Khadheer Pasha, K. K. Sadasivuni, D. Ponnamma, K. Chidambaram, Euro. Polym. J., 76 (2016) 14-27. 25. K. Deshmukh, M. B. Ahamed, K. K. Sadasivuni, D. Ponnamma, R. R. Deshmukh, S. K. K. Pasha, M. A. A. AlMaadeed, J. Polym. Res. 23 (2016)159.

TE D

26. K. Deshmukh, M. B. Ahamed, R. R. Deshmukh, S. K. K. Pasha, K. K. Sadasivuni, D. Ponnamma, M. A. A. AlMaadeed, J. Mater. Sci: Mater Electron (2016) DOI: 10.1007/s10854-016-5559-1

27. K. Deshmukh, M. B. Ahamed, R. R. Deshmukh, S. K. Khadheer Pasha, K.

EP

Chidambaram, K. K. Sadasivuni, D. Ponnamma, M.A.A. AlMaadeed, Polym. Plast. Tech. Eng., 55 (2016) 1240-1253.

AC C

28. J. Y. Wang, S. H. Yang, Y. L. Huang, H. W. Tien, C.C. Ma, J. Mater. Chem., 11 (2011) 13569-13575.

29. D. R. Wang, Y. Bao, J. W. Zha, J. Zhao, Z. M. Dang, G. H. Hu, ACS Appl. Mater. Interfaces, 4 (2012) 6273-6279.

30. L. Jiajie, H. Yi, Z. Long, W. Yan, M. Yanfeng, G. Tianyin, C. Yongsheng, Advanced Functional Materials, 19 (2009) 2297-2302. 31. H. Tsutsumi, S. Fukuzawa, M. Ishikawa, M. Morita, Y. Matsuda, Synth. Met. 72 (1995) 231-235. 32. C. W. Lin, Y.F. Huang, A.M. Kannan, J. Power Sources, 164 (2007) 449-456. 33. C. W. Lin, Y. F. Huang, A. M. Kannan, J. Power Source, 171 (2007) 340-347.

17

ACCEPTED MANUSCRIPT 34. A. K. Sahu, G. Selvarani, S. D. Bhat, S. Pitchumani, P. Sridhar, A. K. Shukla, N. Narayanan, A. Banerjee, N. Chandrakumar, J. Membr. Sci., 319 (2008) 298-305. 35. M. S. Kang, J. H. Kim, J. Won, S. H. Moon, Y. S. Kang, J. Membr. Sci., 247 (2005)127-135. 36. W. S. Hummers, R.E. Offman, J. Am. Chem. Soc., 80 (1958) 1339-1339.

RI PT

37. S.M. Pawde, K. Deshmukh, Polym. Eng. Sci. 49 (2009) 808-818. 38. D. S. Kim, M. D. Guiver, S. Y. Nam, T. II. Yun, M. Y. Seo, S. J. Kim, H. S. Hwang, J. W. Rhim, J. Membr. Sci., 281 (2006) 156-162.

39. F. Kucera, J. Jancer, Polym. Eng. Sci., 38 (1998) 783-792.

SC

40. M. L. Zhu, B. Q. He, W. Y. Shi, Y.H. Feng, C. J. Ding, X.J. Li, F. D. Zeng, Fuel, 89 (2010) 2299-2304.

41. I. Bekri-Abbes, S. Bayoudh, M. Baklouti, J. Polym. Environ., 14 (2006) 249-256.

M AN U

42. R. Surudzic, A. Jankovic, M. Mitric, I. Matic, Z.D. Juranic, L. Zivkovic, V. MiskovicStankovic, K.Y. Rhee, S. J. Park, D. Hui, J. Indus. Eng. Chem. 34 (2016) 250-257. 43. J. Ahmad, K. Deshmukh, M.B. Hagg, Int. J. Polym. Anal. Charac., 18 (2013) 287296.

44. J. Ahmad, K. Deshmukh, M. Habib, M.B. Hagg, Arab. J. Sci. Eng., 39 (2014) 6805-

TE D

6814.

45. K. Deshmukh, J. Ahmad, M.B. Hagg, Ionics, 20 (2014) 957-967. 46. S. M. Pawde, K. Deshmukh, S. Parab, J. Appl. Polym. Sci., 109 (2008) 1328-1337. 47. S. M. Pawde, K. Deshmukh, J. Appl. Polym. Sci., 109 (2008)3431-3437.

EP

48. K. Deshmukh, M. B. Ahamed, S.K. Khadheer Pasha, R. R. Deshmukh, P.R. Bhagat, RSC Advances, 5 (2015) 61933-61945.

AC C

49. S. K. Khadheer Pasha, K. Deshmukh, M. B. Ahamed, K. Chidambaram, M. K. Mohanapriya, N. A. Nambi Raj, Adv. Polym. Tech. (2015). DOI: 10.1002/adv.21616

50. K. Deshmukh, M. B. Ahamed, R. R. Deshmukh, P. R. Bhagat, S. K. K. Pasha, A. Bhagat, R. Shirbhate, F. Telare, C. Lakhani, Polym. Plast. Tech. Eng. 55 (2016) 231-

241.

51. K. N. Kudin, B. Ozbas, H.C. Schniepp, R.K. Prudhomme, I. A. Aksay, R. Car, Nano Lett., 1 (2008) 36-41. 52. Z. Li, R. J. Young, I. A. Kinloch, ACS Appl. Mater. Interfaces, 5 (2013) 456–463 53. O. C. Compton, D. A. Dikin, K. W. Putz, L.C. Brinson, S. T. Nguyen, Adv. Mater., 22 (2010) 892-896.

18

ACCEPTED MANUSCRIPT 54. P. Zou, H. Feng, Z. Xu, L. Zhang, Y. Zhang, W. Xia, W. Zhang, Chem. Cent. J., 7 (2013) 39-49. 55. Z. Xin, S. Z. Katherine, Z. Kun, R. Donald, L. Li, W. Shiren, J. H-W. Louisa, L. W. Brandon, ACS Appl. Mater. Interfaces, 7(2015) 1057-1064. 56. W. Shiren, Z. Yue, A. Noureddine, C. Luis, Langmuir, 25 (2009) 11078-11081.

Int. J. Chem. Tech. Res. 8 (2015) 32-41.

RI PT

57. M. K. Mohanapriya, K. Deshmukh, M. B. Ahamed, K. Chidambaram, S. K. K. Pasha,

58. M. K. Mohanapriya, K. Deshmukh, M. B. Ahamed, K. Chidambaram, S. K. K. Pasha, Materials Today: Proceedings 3 (2016) 1864-1873.

SC

59. K. Deshmukh, M. B. Ahamed, A. R. Polu, K. K. Sadasivuni, S. K. K. Pasha, D.

Ponnamma, M. A. A. AlMaadeed, R. R. Deshmukh, K. Chidambaram, J. Mater Sci: Mater Electron. (2016) DOI: 10.1007/s10854-016-5267-x

M AN U

60. M. K. Mohanapriya, K. Deshmukh, M. B. Ahamed, K. Chidambaram, S. K. K. Pasha, Adv. Mater. Lett. (2016) DOI: 10.5185/amlett.2016.6555

61. K. Deshmukh, M. B. Ahamed, R. R. Deshmukh, S. K. K. Pasha, K. K. Sadasivuni, A. R. Polu, D. Ponnamma, M. A. A. AlMaadeed, K. Chidambaram, J. Mater Sci: Mater Electron. (2016). DOI: 10.1007/s10854-016-5616-9

TE D

62. Sunil G. Rathod, R. F. Bhajantri, V. Ravindrachary, P. K. Pujari, T. Sheela, Jagadish Naik, AIP Conference Proceedings 1591 (2014) 1769 (4 pages). 63. Badapanda. T, Senthil. V, Anwar. S, Cavalcante. L. S, Batista. N. C, Longo. E, Current Applied Physics 13 (2013) 1490-1495.

EP

64. Chakrabortya. G, Meikapa. A. K, Babub. R, Blau. W. J, Solid State Communications 151 (2011) 754–758.

AC C

65. Uma. S, Philip. J, Indian Journal of Pure and Applied Physics, 51 (2013) 717-723.

19

ACCEPTED MANUSCRIPT

TE D

M AN U

SC

RI PT

Figures and Tables:

AC C

EP

Fig. 1: Protocol for the synthesis of PSSA/PVA/GO composites. The photographs of bottles shows PSSA/PVA/GO dispersion having different GO loadings (a) 0.5 wt % GO (b) 1 wt % GO (c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % GO (f) 3 wt % GO. The photographs of PSSA/PVA/GO composite films with different GO loadings are also shown where (a) 0.5 wt % GO (b) 3 wt % GO (c) composite film is bent to demonstrate its flexibility.

20

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

Fig. 2: Photographs of PSSA/PVA/GO composite films with different GO loading (a) PSSA/PVA (50/50) blend (b) 0.5 wt % GO (c) 1 wt % GO (d) 1.5 wt % GO (e) 3 wt % GO.

21

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 3: Schematic representation of the possible interaction between PSSA, PVA and GO.

22

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 4: FTIR spectra of PSSA/PVA/GO composite films (a) 0.5 wt % GO (b) 1 wt % GO

AC C

EP

TE D

(c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % (f) 3 wt % GO.

Fig. 5: Raman spectra of Graphite, GO and PSSA/PVA/GO composite films (a) Graphite (b) GO (c) 0.5 wt % GO (d) 1 wt % GO (e) 1.5 wt % GO(f) 2 wt % GO (g) 3 wt % GO.

23

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 6: XRD spectra of PSSA/PVA/GO composite films (a) 0.5 wt % GO (b) 1 wt % GO

AC C

EP

TE D

(c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % (f) 3 wt % GO.

24

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

EP

Fig. 7: SEM micrographs of PSSA/PVA/GO composites (a) 0.5 wt% GO (b) 1 wt% GO

AC C

(c) 1.5 wt% GO (d) 2 wt% GO (e) 2.5 wt% GO (f) 3 wt% GO.

25

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 8: AFM topographic images of PSSA/PVA blend and PSSA/PVA/GO composite films (a) PSSA/PVA blend (b) 0.5 wt% GO(c) 1 wt% GO (d) 1.5 wt% GO (e) 2 wt% GO (f) 2.5 wt% GO (g) 3 wt% GO.

26

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 9 (a): Dielectric constants of PSSA/PVA (50/50) blends as a function of frequency at

AC C

EP

TE D

various temperatures.

Fig. 9 (b): Dielectric constants of PSSA/PVA/GO composites with 0.5 wt% GO loading as a function of frequency at various temperatures.

27

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 9 (c): Dielectric constants of PSSA/PVA/GO composites with 1 wt% GO loading as a

AC C

EP

TE D

function of frequency at various temperatures.

Fig. 9 (d): Dielectric constants of PSSA/PVA/GO composites with 1.5 wt% GO loading as a function of frequency at various temperatures.

28

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 9 (e): Dielectric constants of PSSA/PVA/GO composites with 2 wt% GO loading as a

AC C

EP

TE D

function of frequency at various temperatures.

Fig. 9 (f): Dielectric constants of PSSA/PVA/GO composites with 2.5 wt% GO loading as a function of frequency at various temperatures.

29

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 9 (g): Dielectric constants of PSSA/PVA/GO composites with 3 wt% GO loading as a

AC C

EP

TE D

function of frequency at various temperatures.

Fig. 10 (a): Dielectric loss tangent (tan δ) plots of PSSA/PVA blend (50/50) as a function of frequency at various temperatures.

30

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 10 (b): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 0.5 wt%

AC C

EP

TE D

GO loading as a function of frequency at various temperatures.

Fig. 10 (c): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 1 wt% GO loading as a function of frequency at various temperatures.

31

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 10 (d): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 1.5 wt%

AC C

EP

TE D

GO loading as a function of frequency at various temperatures.

Fig. 10 (e): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 2 wt% GO loading as a function of frequency at various temperatures.

32

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 10 (f): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 2.5 wt%

AC C

EP

TE D

GO loading as a function of frequency at various temperatures.

Fig. 10 (g): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 3 wt% GO loading as a function of frequency at various temperatures.

33

ACCEPTED MANUSCRIPT Table 1: Feed compositions of PSSA/PVA/GO composites. PVA (wt %) 50

GO (wt %) 0

2

29.5

70

0.5

3

29

70

1

4

28.5

70

1.5

5

28

70

6

27.5

70

7

27

70

RI PT

1

PSSA (wt %) 50

2

2.5 3

SC

No.

Table 2: Surface roughness parameters obtained from AFM images for PSSA/PVA blend

Samples PSSA/PVA blend 0.5 wt % GO loading 1 wt % GO loading

2 wt % GO loading 2.5 wt % GO loading

Sq (nm)

8.71

11.14

9.11

11.75

9.51

12.98

28.62

38.80

33.19

44.12

57.32

84.29

75.85

101.29

EP

3 wt % GO loading

Sa (nm)

TE D

1.5 wt % GO loading

.

M AN U

and PSSA/PVA/GO composite films.

Table 3: Water contact angle (θo), surface energy (mJ/m2) and work of adhesion (mJ/m2) for

AC C

PSSA/PVA blend and PSSA/PVA/GO composite films. Samples

Contact angle

Surface energy

Work of adhesion

(θo)

(mJ/m2)

(mJ/m2)

PSSA/PVA blend

78.15+ 0.06

36.64 + 0.04

86.71

0.5 wt % GO Loading

48.70+ 0.05

54.51 + 0.03

119.47

1 wt % GO Loading

50.84+ 0.07

52.02 + 0.03

117.41

1.5 wt % GO Loading

53.18+ 0.05

51.91 + 0.03

115.10

2 wt % GO Loading

61.51+ 0.05

46.92 + 0.03

106.30

2.5 wt % GO Loading

65.86+ 0.01

44.27 + 0.01

101.40

3 wt % GO Loading

66.21+ 0.05

44.05 + 0.03

101.00

34

ACCEPTED MANUSCRIPT Table 4: Summary of dielectric properties of PSSA/PVA/GO composites with different GO loadings.. GO Loading (wt%)

Dielectric Constant (ε)

1

0

82.67, 50 Hz, 150oC

Dielectric Loss Tangent (tanδ) 1.56, 50 KHz, 140oC

2

0.5

118.79, 50 Hz, 150oC

1.69, 50 KHz, 140oC

3

1

150.05, 50 Hz, 150oC

1.73, 50 KHz, 140oC

4

1.5

163.31, 50 Hz, 150oC

1.79, 50 KHz, 140oC

5

2

191.38, 50 Hz, 150oC

2.17, 50 KHz, 140oC

6

2.5

262.40, 50 Hz, 150oC

2.42, 50 KHz, 140oC

7

3

297.91, 50 Hz, 150oC

2.64, 50 KHz, 140oC

M AN U

SC

RI PT

No.

Table 5: Comparison of dielectric constant obtained for PSSA/PVA/GO composites and PVA composite from literature. Filler

PVA/PVDF -rGO PVA/GO PVA/BZT PVA/ MWCNT PVA/PZT PSSA/ PVA/GO

2.2 vol% 5 wt % 50 vol% 10 wt%

Dielectric Loss Tangent (tanδ)

Frequency (Hz)

Temp (oC)

Ref

225

0.5

2

RT

29

800 1350 95

10 1.2 350

3 100 300

RT 120 150

62 63 64

1.7 2.6

2 50

RT 150

65 Present work

Dielectric Constant (ε)

EP

TE D

Composite

AC C

3 wt % 3 wt %

110 297.91

35

ACCEPTED MANUSCRIPT Figures and Table Captions:

Fig. 1: Protocol for the synthesis of PSSA/PVA/GO composites. The photographs of bottles shows PSSA/PVA/GO dispersion having different GO loadings (a) 0.5 wt % GO (b) 1 wt % GO (c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % GO (f) 3 wt % GO.

RI PT

The photographs of PSSA/PVA/GO composite films with different GO loadings are also shown where (a) 0.5 wt % GO (b) 3 wt % GO (c) composite film is bent to demonstrate its flexibility.

Fig. 2: Photographs of PSSA/PVA/GO composite films with different GO loading

SC

(a) PSSA/PVA (50/50) blend (b) 0.5 wt % GO (c) 1 wt % GO (d) 1.5 wt % GO (e) 3 wt % GO.

M AN U

Fig. 3: Schematic representation of the possible interaction between PSSA, PVA and GO. Fig. 4: FTIR spectra of PSSA/PVA/GO composite films (a) 0.5 wt % GO (b) 1 wt % GO (c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % (f) 3 wt % GO. Fig. 5: Raman spectra of Graphite, GO and PSSA/PVA/GO composite films (a) Graphite (b) GO (c) 0.5 wt % GO (d) 1 wt % GO (e) 1.5 wt % GO (f) 2 wt % GO (g) 3 wt % GO.

TE D

Fig. 6: XRD spectra of PSSA/PVA/GO composite films (a) 0.5 wt % GO (b) 1 wt % GO (c) 1.5 wt % GO (d) 2 wt % GO (e) 2.5 wt % (f) 3 wt % GO. Fig. 7: SEM micrographs of PSSA/PVA/GO composites (a) 0.5 wt% GO (b) 1 wt% GO (c) 1.5 wt% GO (d) 2 wt% GO (e) 2.5 wt% GO (f) 3 wt% GO.

EP

Fig. 8: AFM topographic images of PSSA/PVA blend and PSSA/PVA/GO composite films (a) PSSA/PVA blend (b) 0.5 wt% GO (c) 1 wt% GO (d) 1.5 wt% GO

AC C

(e) 2 wt% GO (f) 2.5 wt% GO (g) 3 wt% GO.

Fig. 9 (a): Dielectric constants of PSSA/PVA (50/50) blends as a function of frequency at various temperatures.

Fig. 9 (b): Dielectric constants of PSSA/PVA/GO composites with 0.5 wt% GO loading as a function of frequency at various temperatures.

Fig. 9 (c): Dielectric constants of PSSA/PVA/GO composites with 1 wt% GO loading as a function of frequency at various temperatures. Fig. 9 (d): Dielectric constants of PSSA/PVA/GO composites with 1.5 wt% GO loading as a function of frequency at various temperatures.

36

ACCEPTED MANUSCRIPT Fig. 9 (e): Dielectric constants of PSSA/PVA/GO composites with 2 wt% GO loading as a function of frequency at various temperatures. Fig. 9 (f): Dielectric constants of PSSA/PVA/GO composites with 2.5 wt% GO loading as a function of frequency at various temperatures. Fig. 9 (g): Dielectric constants of PSSA/PVA/GO composites with 3 wt% GO loading as a

RI PT

function of frequency at various temperatures. Fig. 10 (a): Dielectric loss tangent (tan δ) plots of PSSA/PVA blend (50/50) as a function of frequency at various temperatures.

Fig. 10 (b): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 0.5 wt%

SC

GO loading as a function of frequency at various temperatures.

Fig. 10 (c): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 1 wt% GO loading as a function of frequency at various temperatures.

M AN U

Fig. 10 (d): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 1.5 wt% GO loading as a function of frequency at various temperatures. Fig. 10 (e): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 2 wt% GO loading as a function of frequency at various temperatures. Fig. 10 (f): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 2.5 wt%

TE D

GO loading as a function of frequency at various temperatures. Fig. 10 (g): Dielectric loss tangent (tan δ) plots of PSSA/PVA/GO composites with 3 wt% GO loading as a function of frequency at various temperatures. Table 1: Feed composition of PSSA/PVA/GO composites.

EP

Table 2: Surface roughness parameters obtained from AFM images for PSSA/PVA blend and PSSA/PVA/GO composite films.

AC C

Table 3: Water Contact angle (θo), surface energy (mJ/m2) and work of adhesion (mJ/m2) for PSSA/PVA/GO composite films.

Table 4: Summary of dielectric properties of PSSA/PVA/GO composites with different GO loadings.

ACCEPTED MANUSCRIPT Highlights:


Graphene Oxide was prepared from natural graphite using modified Hummers method.

blend matrix.

RI PT


Novel PSSA/PVA/GO composites were prepared by reinforcing GO into PSSA/PVA
Molecular level dispersion of GO in PSSA/PVA blend matrix was successfully achieved.

GO in PSSA/PVA blend matrix..

SC


Enhancement in the dielectric constant was observed due to effective reinforcement of
PSSA/PVA/GO composites with high dielectric performances can be considered for

AC C

EP

TE D

M AN U

energy storage applications.