research article structural and electrochemical...

Research ArticleStructural and Electrochemical Analysis of PMMA Based GelElectrolyte Membranes

Chithra M Mathew K Kesavan and S Rajendran

Department of Physics Alagappa University Karaikudi Tamil Nadu 630 004 India

Correspondence should be addressed to S Rajendran sraj54yahoocom

Received 24 September 2014 Revised 19 December 2014 Accepted 23 December 2014

Academic Editor Sheng S Zhang

Copyright copy 2015 Chithra M Mathew et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

New gel polymer electrolytes containing poly(vinylidene chloride-co-acrylonitrile) and poly(methyl methacrylate) are preparedby solution casting method With the addition of 60wt of EC to PVdC-ANPMMA blend ionic conductivity value 0398 times10minus6 S cmminus1 has been achieved XRD and FT-IR studies have been conducted to investigate the structure and complexation in the

polymer gel electrolytes The FT-IR spectra show that the functional groups C=O and CequivN play major role in ion conductionThermal stability of the prepared membranes is found to be about 180∘C

1 Introduction

During the past two decades solid-state polymer and poly-mer gel electrolytes have attracted great interest because ofthe possibility of their usage in lithium batteries becausepolymer gel electrolytes are leakage-free and have muchhigher ionic conductivity The dissolution of low latticeenergy salts into a solvating polymer leads to the formationof polymer electrolyte These can conduct ions and themobility of these ions can be improved by the addition ofplasticizers [1] A number of methods have been reportedfor improving the ionic conductivity andmechanical stabilityof polymer electrolytes including copolymerization graft-ing physical cross-linking blending plasticization and theaddition of inert ceramic oxides to the matrix Numerousstudies have been carried out on polyacrylonitrile (PAN)poly(vinylidene fluoride) (PVdF) poly(methyl methacrylate)(PMMA) poly(vinyl chloride) (PVC) [2] poly(vinyl acetate)(PVAc) poly(ethylene oxide) (PEO) and so forth Althoughthese polymer electrolytes exhibit high ionic conductivitiesexceeding 10minus5 S cmminus1 after blending most of them havevarious deficiencies preventing them from being used incommercial lithium batteries [3]

Optimized PVdC-ANPMMA blend ratio on the basisof electrochemical analysis has been reported as 5050wt

in our previous work [4] It has been reported that theaddition of plasticizer can enhance the polymer flexibilityand hence the better ionic conduction In order to providea detailed description about the effect of plasticizer onthe poly(vinylidene chloride-co-acrylonitrile) (PVdC-AN)membranes three different formulations of PVdC-AN elec-trolyte films have been prepared and analysed using vari-ous techniques such as FT-IR Electrochemical Impedanceanalysis and X-ray diffraction LiBF

4

has been chosen asionic salt in this present study since it has low lattice energyThe dielectric constant of the plasticizer is an importantparameter that affects the ionic conduction Higher dielectricconstant results in better dissociation of the salt as the num-ber of free mobile charge carriers increased The researcherswho initiated the study on LiBF

4

mentioned the multipleadvantages of LiBF

4

as compared with other lithium salts(eg less toxicity than LiAsF

6

and higher safety than LiClO4

)In the present study one of the host polymers used is PMMAsince it is an amorphous polymer with excellent mechanicalproperty and is less reactive towards the lithiumelectrode andit induces favourable passivation of ions [5] Also PVdC-ANandPMMAhelp better electron pair formation of CequivNC=Oand CminusOminusC which can coordinate with cations from lithiumsalt to form polymer-salt complexes and hence provide ionicconduction [6]

Hindawi Publishing CorporationInternational Journal of ElectrochemistryVolume 2015 Article ID 494308 7 pageshttpdxdoiorg1011552015494308

2 International Journal of Electrochemistry

2 Materials and Methods

Poly(vinylidene chloride-co-acrylonitrile) (PVdC-AN Avg119872119908

150000 Aldrich USA) poly(methyl methacrylate)(PMMA Avg 119872

119908

120000 Aldrich USA) plasticizer ethy-lene carbonate EC (Alfa Aesar India) and electrolyte saltlithium tetrafluoroborate (LiBF

4

Aldrich USA) were usedas received All electrolyte membranes were prepared bysolution casting technique Appropriate weights of PVdC-AN PMMA and LiBF

4

were dissolved separately in theorganic solvent tetrahydrofuran (THFMerck India) at roomtemperature The polymer and salt solutions were mixed andthen stirred continuously for 12 h to obtain a homogeneoussolution The plasticizer ethylene carbonate was added to thepolymer solution with ratios 20 40 60 and 80wt Theobtained homogeneous highly viscous solution was alloweddegassing to remove air bubbles and cast onto the well-cleaned petri-dishes to get the desired thin film membranesThen the solvent was allowed to evaporate slowly at 60∘Cfor about 6 h using vacuum oven Finally the harvested elec-trolyte membranes were analysed using various techniquesThe PVdC-ANPMMA blend electrolyte membrane with80wt ethylene carbonate could not form a freestandingfilm and was in the form of a gel at room temperature Themembranes with 20 40 and 60wt of EC were denoted asR1 R2 and R3 respectively

The X-ray diffraction patterns were recorded with acomputer controlled Xrsquopert PRO PANalytical diffractome-ter in the scanning range 2120579 = 10 to 80∘ using Cu-K120572(wavelength 120582 = 1541 A) radiation as a source The FourierTransform Infrared (FT-IR) spectra of the samples wererecorded withThermofisher Nicolet iS10 FT-IR Spectrometerin the range of 4000ndash400 cmminus1 in the transmittance modeThe electrochemical analysis of the polymer electrolytes wascarried out by sandwiching the electrolyte film betweenstainless steel blocking electrodes using 120583-Autolab Type-IIIPotentiostatGalvanostat in the frequency range 1Hzndash1MHzThe measurements were taken between 303K and 353KThevalue of bulk resistance 119877

119887

was found to be the intercept onthe 119909-axis of the impedance plot The conductivity (120590) wascalculated using

120590 =119897

119877119887

119860 (1)

where 119897 is the thickness of the polymer electrolyte film 119877119887

isthe bulk resistance and 119860 is the surface area of the polymerelectrolyte film [7]

All the polymer complexes were subjected to thermalanalysis which was carried out using Perkin Elmer Pyris-6 TGDTA Analyzer The thermogravimetric curves wererecorded in nitrogen atmosphere from room temperatureto 600∘C The heating rate was 10∘Cmin From TG plotstemperature of maximum process rate temperature at theend of decomposition and weight loss were determined

3 Results and Discussion

31 Structural Analysis Structural analysis of the preparedpolymer complexes was carried out using X-ray diffraction

PVdC-AN

PMMA

R1

R2

R3

10 20 30 40 50 60 70 80

Inte

nsity

(au

)

(101

)

(020

) (202

)(0

22)

(311

)

Angle 2120579 (deg)

LiBF4

Figure 1 XRD patterns of PVdC-ANPMMAECLiBF4

mem-branes

method The diffraction pattern of PVdC-ANPMMA-ECLiBF

4

based membranes is shown in Figure 1The graphsshow that PVdC-AN exhibits semicrystalline peaks at angles2120579 = 4025 4676 and 6794∘ and PMMA shows an amor-phous natureThe intense peaks of LiBF

4

in Figure 1 at angles2120579 = 187 267 281 377 446 528 and 5793∘ reveal the crys-talline nature of the ionic salt All of these crystalline peaks arefound to have disappeared when the polymer plasticizer andsalt were mixed togetherThus XRD patterns of the preparedpolymer membranes in Figure 1 reveal the amorphous naturewhich is essential for a polymer electrolyte The interactionbetween the polymer atoms plasticizer and lithium ionsdisturbed the polymer network which leads to a decrease incrystallinity The amorphous nature of complexes indicatesthat the lithium salt is not crystallized in the film but rathermolecularly dispersed within the polymer in the presenceof EC With the increase in the content of EC complexesbecame completely amorphous without any trace of diffrac-tion halos It is known that high intensity diffraction peaksare associated with high crystallinity and broader diffractionhumps for their semicrystallineamorphous nature Hencethe broadening of diffraction peaks reveals the enhancementof the amorphous nature of PVdC-ANPMMALiBF

4

ECpolymer electrolyte membranes In addition the absencesof diffraction peaks of both polymer and salt in preparedcomplexes reveal the good miscibility of polymer and saltwith plasticizer at the molecular level These results suggestthat the incorporated lithium salts were dissolved in theamorphous region of polymer in the presence of plasticizerand the ionic conductivity of polymer electrolyte given by theamorphous phase of the complex [8]

32 Functional Group Analysis The FT-IR spectra of PVdC-ANPMMA electrolyte membranes are shown in Figure 2The spectra of pure samples such as PVdC-AN PMMA EC

International Journal of Electrochemistry 3

4000 3500 3000 2500 2000 1500 1000 500

R3

PVdC-AN

C-H

C=O

C-HPMMA O=H

Tran

smitt

ance

()

R1

R2

EC

C=O

Wavenumber (cmminus1)

CequivN

120572-Methyl120572-Methyl

Figure 2 FT-IR transmission spectra of PVdC-ANPMMAEC-LiBF4

membranes

and LiBF4

are also included in both graphs for the com-parison purpose The ndashCH

2

asymmetric stretching C(Cl2

)symmetric stretching and the C(Cl

2

) bending of vinylidenechloride in pure PVdC-ANwere observed at 1038ndash1073 cmminus1751ndash656ndash606 cmminus1 and 568ndash446 cmminus1 respectively in thespectrum of the copolymer However in the spectra of poly-mer electrolytes these bands are found shifted in complexesas ethylene carbonate (EC) ratio decreases which is dueto the structural reorganization of the polymer The strongstretching vibration of the Nitrile group CequivN of PVdC-AN isobserved at 2247 cmminus1 in the complexes [9] In acrylonitrile-based electrolytes the Li+ ions associate with the nitrogenatoms since the Nitrile is a strong electron dopant whereasin methacrylate-based electrolytes the lithium ions associatewith oxygen atoms It is clear that when the compositionof EC is increased the transmittance intensity of the CequivNgroup in PVdC-AN is decreased and can be explained bythe interaction between functional groups of both polymersand it may vary with the composition This signifies thestrong interaction of Li+ ions with the Nitrile group Itis clear that as the plasticizer composition increases thefree volume between the polymer chains and the segmentalmobility increases hence the vibrational intensity in thespectra gets reducedThese two conditions enhance the fasterconduction of mobile ions Also the symmetrical stretchingof the carbonyl group 120583(C=O) at 1725 cmminus1 and ether group(CminusOminusC) at 1100minus1200 cmminus1 in PMMA [10] had been foundto be broadened and intensity is reduced significantly in thecomplexes It can be observed that the C=O bending bandwhich appears at 718 cmminus1 in the spectrum of pure EC hasshifted to higher wavenumber region in all the complexes andhas become more intense as EC composition increases Thismay be due to the interaction between Li+ of the salt andC=O bending band [11] The vibrational band at 1073 cmminus1 of

R1R2R3

1 10 100 1k 10k 100 k 1M10minus9

10minus8

10minus7

10minus5

10minus6

120590998400 (S

cmminus

1 )

Frequency f (Hz)

Figure 3 Variation of ac conductivity with respect to frequency forPVdC-ANPMMAECLiBF

4

membranes

BF4

minus anion observed in the polymer complexes indicates thedissociation of LiBF

4

in the polymer [12] It is very clear thatthe characteristic peak CequivN is more intense in the spectraof polymer complex than in pure PVdC-AN which revealsthe good miscibility and strong bonding between PVdC-ANand PMMAThe vibrational peaks at 1388 cmminus1 and 754 cmminus1can be attributed to the 120572-methyl group vibrations and thepeak at 1444 cmminus1 can be assigned as bending vibration of theCndashH bonds of the ndashCH

3

group in PMMA and are foundshifted in the complexes [13] Based on this finding webelieve that the oxygen atom from PMMA contributed to thestronger interaction with lithium cation than the nitrogenatom from PVdC-AN in blend membranes while Nitrilegroup alone makes good interaction with lithium cation insingle polymer membranes The presence of ndashOH grouparound 3500 cmminus1 in the spectra ofmembranesmay be due tothe absorption of moisture during sample loading for FT-IRanalysis

33 Conductance Spectra Thevariation of120590ac with frequencyof different compositions of PVdC-ANPMMA at room tem-perature has been given in Figure 3 Generally the electrodepolarization direct current conductivity and the dielec-tric relaxation phenomena could be distinguished at lowintermediate and high frequencies respectively [14] Fromthe figure it can be seen that the low frequency electrodeeffects represented by the deviation from flat conductivityare completely absent in all the films The ac conductivitypatterns show frequency independent plateau in the lowfrequency region and exhibit dispersion at higher frequenciesowing to the contribution of polymer segmental motionThisbehaviour obeys Jonscher power law 120590ac(120596) = 120590dc + 119860120596

119899where 120590dc is the dc conductivity (frequency independentplateau in the low frequency region) 119860 is the preexponential


00

303K313K323K

333K343K353K

Z998400 (Ohm)

minusZ998400998400

(Ohm

)

10k 20k 30k 40k 50k

10k

20k

30k

40k

50k

Figure 4 Impedance response of R3 = PVdC-ANPMMAEC-LiBF4

polymer electrolyte membranes at different temperature

factor 120596 is the angular frequency (120596 = 2120587119891) and 119899 isthe fractional exponent [15] The values of 120590dc 119860 and 119899are determined by fitting the 120590ac(120596) = 120590dc + 119860120596

119899 and aretabulated in Table 1 Generally for ionic conductors powerlaw exponents (119899) can be between 1 and 0 indicating the ideallong-range pathways and diffusion limited hopping (tortuouspathway) respectively The highest dc conductivity of theionically conducting polymer electrolytes is found in theorder of 10minus6 S cmminus1 for R3 (EC = 60wt) in Figure 3

34 Ionic Conductivity Studies In conductance spectra thehighest ionic conductivity has been observed for R3 =PVdC-AN(46)PMMA(46)LiBF

4

(8)EC(60) membranes inthe overall range of temperatures studied The typicalimpedance plot for the polymer membrane R3 from roomtemperature to 353K is shown in Figure 4 It is found that asthe plasticizer ratio increases the ionic conductivity valuesalso increase which is due to the increment of the mobilityof charge carriers in the polymer-salt complexesThis may bedue to the plasticizer which enhances the polymer segmentalmobility and the number of free volumes between thepolymer chains and hence leads to greater conduction ofmobile ions The maximum ionic conductivity is found tobe for the membrane with 60wt of plasticizer This maybe due to the oxygen atom from PMMA contributing to thestrong interaction with lithium cation when plasticizer ratioincreased which is in accordance with FT-IR spectra

The variations of log120590 with the inverse of absolute tem-perature for all the prepared polymer electrolyte films are pre-sented in Figure 5 The figure shows that the increase of tem-perature increases the conductivity of polymer electrolytesover the temperature range studiedThe nonlinear behaviourof the temperature dependence of the ionic conductivity canbe explained usingVTF (Vogel-Tamman-Fulcher) expression120590 = 119860119879

minus12 exp(minus119861119870(119879 minus 1198790

)) where 119860 is a constant

28 29 30 31 32 33 34

R1R2R3

minus90

minus80

minus70

minus60

minus50

minus40

minus30

1000T (Kminus1)

(S cm

minus1 )

log120590

Figure 5 Plot of temperature versus log conductivity for PVdC-ANPMMAECLiBF

4

proportional to the number of charge carriers119861 is a constantand 119879

0

is the temperature at which configurational entropybecomes zero This reveals that the ionic conductivity andviscoelastic properties of polymer electrolytes are closelyrelated to each other Due to the addition of the plasticizingagent ethylene carbonate (EC) to polymer combinations theviscosity of complex gets reduced Since both macroscopicflow of polymer and local segmental motion are possiblefor viscous solutions it is suggested that the local segmentalmotion plays an important role in ion-migration in thepolymer electrolytes [16]

The diffusion theory can explain well the change inconductivity with respect to temperature The diffusion coef-ficient of small particles in such amorphous polymer elec-trolyte media can be expressed as 119863 = 119892119889V exp(minus120574119881lowast119881

119891

)where 119892 cong 16 119889 is the distance through which theparticles are transported (effectively a molecular diameter)V is the velocity of the particle (proportional to 11987912) 120574is a factor to allow for overlap of free volume 119881lowast is thecritical volume required for migration of the particle and119881119891

is the free volume of the medium The basic conceptof diffusion theory is that transport of the particles in amedium depends upon the formation of holes large enoughfor diffusive displacementThe statistical redistribution of thefree volume results in hole formation and its probability isgiven by the exponential term of the diffusion coefficient [17]The diffusion coefficient and ionic conductivity can be relatedby Nernst-Einstein relation Therefore a good fit of theconductivity data of plasticized electrolytes to VTF relationimplies that the conductivity change with temperature isdominated by the change in the diffusion coefficient (ionicmobility) which can be explained by free volumemechanismThe carrier lithium ions in the polymer electrolyte movefrom one site to another and will be redistributed around thesite when the free volume is large enough for their diffusive


Table 1 Comparison of parameters obtained from fitting the experimental data to power law 120590ac(120596) = 120590dc + 119860120596119899 of PVdC-

ANPMMAECLiBF4 at room temperature

Serial number PVdC-ANPMMALiBF4EC (wt) 120590dc (10minus7) (S cmminus1) 119860 119899

R1 4646820 00025 411119864 minus 10 049R2 4646840 00308 245119864 minus 10 058R3 4646860 04371 363119864 minus 11 087

0

500

1000

1500

2000

2500

R1R2R3

Frequency (Hz)1 10 100 1k 10k 100 k 1M

120576998400

(a)

0

1000

2000

3000

4000

5000

6000

Frequency (Hz)R1R2R3

1 10 100 1k 10k 100 k 1M

120576998400998400

(b)

Figure 6 Dielectric constant (a) and dielectric loss (b) versus frequency

displacement (lt119881lowast119894

) The polymer segments associated withions continuously rearrange because the electrolytes are ina rubbery state This redistribution of free volume is mainlycaused by the segmental motion in polymer electrolytes andthis rearrangement changes the local position of the carrierions Thus it can be seen that the ion-migration does nothappen by itself Thus the repeating of the association of thecarrier ions to the polymer segments the segmental motionwith associated ions and the dissociation from the polymersegments may result in ionic transportTherefore it is provedthat the temperature dependence of ionic conductivity andsegmental mobility closely correlate with each other

35 Dielectric Studies The dielectric response is generallydescribed by the complex permittivity 120576lowast = 1205761015840 minus 11989412057610158401015840 wherereal 1205761015840 (or the dielectric constant 120576

119903

) and imaginary 12057610158401015840 (ordielectric loss 120576

119894

) components are the storage and loss ofenergy in each cycle of applied electric field Figures 6(a) and6(b) show the variation of dielectric constants (1205761015840 and 12057610158401015840) withfrequency for different EC value of PVdC-ANPMMA basedpolymer blend electrolytes It can be seen that both 1205761015840 and 12057610158401015840are dispersed at lower frequency and they are independent athigher frequency The dielectric constant is found decreasedwith the increase in frequency for all concentrations whichmay be due to relaxation process [18]

0 100 200 300 400 5000

20

40

60

80

100R2

R3R1

Wei

ght (

)

R1R2R3

Temperature (∘C)

Figure 7 Thermogravimetric (TG) curves of polymer membranes

36 Thermogravimetric Analysis It is noted from Figure 7that the TGA of polymer complexes R1 R2 and R3 exhibittwo-step degradation All the samples almost completed the


decay (weight loss is about 80) at the end of the process thatis at 500∘C The samples R1 R2 and R3 show weight loss ofabout 3 2 and 3 respectively at 90∘C and this weight lossmay be due to the moisture or by the evaporation of residualsolvent which is used in the sample preparation The two-degradation steps at 200 and 383∘C are generally attributedto scissions at the chain-end initiation and random internalscission of the polymer chain respectively During thermaldegradation of PMMA the production of free radicals atlow temperature participates in the further depolymerizationat high temperatures through chain transfer processes Eventhough vinylidene chloride polymers are extremely resistantto biodegradation oxidation and permeation of small par-ticles they are extremely durable under most conditionsHowever when these types of polymers are heated above120∘C they are thermally unstable and undergo a degrada-tive dehydrochlorination [19] The significant change in thepolymerrsquos original highly ordered structure at 170∘C in TGAplot can be observed which indicates the breakage of CH

2

bonds in the polymer chain and the expansion of the CndashClcarbon-halogen bonds which leads to the elimination of thehalogen atoms at sites along the polymer chain [20]Thus theloss of the chlorine atoms from the polymer chain results in asignificant change in the stability of the polymer electrolyteSince degradation apparently begins in VDC units adjacentto comonomer units acrylonitrile copolymers release a smallamount of ammonia and hydrogen cyanide (HCN) as well ashydrogen chloride (HCl) and methyl methacrylate polymersrelease methyl chloride in addition to hydrogen chloride onthermal degradation [21] All the prepared samples incorpo-rating different ratios of ethylene carbonate exhibitmaximumthermal stability of about 180∘C and show appreciable weightlosses of about 12 10 and 12 respectively at 180∘C Theweight loss observed in the temperature range 180ndash270∘Cis mainly due to the degradation of polymer lithium saltand plasticizer The second-step degradation of membranesshows weight losses of 58 59 and 59 at 383∘CThe residualmass of about 20 at 600∘C can be assigned to the carbona-ceous residue formed in both previous stages The resultsobtained show that the degradation process of the polymerelectrolyte complexes depends not only on their compositionbut also on the chemical structure of the componentswhereby the components of various concentrations exhibitmutual interactions [22]

4 Conclusion

PVdC-AN-based polymer electrolytes were prepared by sol-vent casting technique The polymer electrolytes with plas-ticizer EC and PMMA have been subjected to EIS FT-IRand also XRD studies With the addition of 60wt of ECto PVdC-ANPMMA blend ionic conductivity of 0398 times10minus6 S cmminus1 has been achieved The increase of temperaturenonlinearly increases the ionic conductivity of polymercomplex over the studied temperature range XRD resultssuggest that the incorporated lithium salts were dissolvedin the amorphous region of polymer in the presence ofplasticizer and the ionic conductivity of polymer electrolyte is

given by the amorphous phase of the complex The complexformation of polymer electrolyte was confirmed from FT-IR spectra The thermal analysis leads to the conclusion thatdegradation process of gel polymer electrolyte depends notonly on the chemical structure of the components but alsoon their composition where the components of the variousratios exhibit mutual interactions

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors thank the University Grants Commission(UGC) Government of India for the financial support (F no40-4592011(SR))

References

[1] M S Ding ldquoConductivity and viscosity of PC-DEC and PC-ECsolutions of LiBF4rdquo Journal of the Electrochemical Society vol151 no 1 pp A40ndashA47 2004

[2] D K Roh J T Park S H Ahn H Ahn D Y Ryu and JH Kim ldquoAmphiphilic poly(vinyl chloride)-g-poly(oxyethylenemethacrylate) graft polymer electrolytes interactions nanos-tructures and applications to dye-sensitized solar cellsrdquo Elec-trochimica Acta vol 55 no 17 pp 4976ndash4981 2010

[3] J R Kim SW Choi SM JoW S Lee and B C Kim ldquoElectro-spun PVdF-based fibrous polymer electrolytes for lithium ionpolymer batteriesrdquo Electrochimica Acta vol 50 no 1 pp 69ndash752004

[4] W-P Hsu and C-F Yeh ldquoMiscibility studies of binary andternary mixtures of tactic poly(methyl methacrylates) withpoly(vinylidene chloride-co-acrylonitrile)rdquo Journal of AppliedPolymer Science vol 75 no 10 pp 1313ndash1321 2000

[5] C M Mathew K Kesavan and S Rajendran ldquoDielectric andthermal response of poly[(vinylidene chloride)-co-acryloni-trile]poly(methyl methacrylate) blend membranesrdquo PolymerInternational 2014

[6] M Ulaganathan C M Mathew and S Rajendran ldquoHighlyporous lithium-ion conducting solvent-free poly(vinylidenefluoride-co-hexafluoropropylene)poly(ethyl methacrylate)based polymer blend electrolytes for Li battery applicationsrdquoElectrochimica Acta vol 93 pp 230ndash235 2013

[7] R Baskaran S Selvasekarapandian G Hirankumar and M SBhuvaneswari ldquoVibrational ac impedance and dielectricspectroscopic studies of poly(vinylacetate)-NN-dimethylfor-mamide-LiClO

4

polymer gel electrolytesrdquo Journal of PowerSources vol 134 no 2 pp 235ndash240 2004

[8] B K Money K Hariharan and J Swenson ldquoA dielectric relax-ation study of nanocomposite polymer electrolytesrdquo Solid StateIonics vol 225 pp 346ndash349 2012

[9] T Hwang L Pu S W Kim Y-S Oh and J-D NamldquoSynthesis and barrier properties of poly(vinylidene chloride-co-acrylonitrile)SiO

2

hybrid composites by sol-gel processrdquoJournal of Membrane Science vol 345 no 1-2 pp 90ndash96 2009

[10] A Ahmad M Y A Rahman M S Sursquoait and H HamzahldquoStudy of MG49-PMMA based solid polymer electrolyterdquo TheOpen Materials Science Journal vol 5 pp 170ndash177 2011


[11] Z Osman and A K Arof ldquoFTIR studies of chitosan acetatebased polymer electrolytesrdquo Electrochimica Acta vol 48 no 8pp 993ndash999 2003

[12] S-W Song T J Richardson G V Zhuang T M Devine andJ W Evans ldquoEffect on aluminum corrosion of LiBF

4

additioninto lithium imide electrolyte a study using the EQCMrdquoElectrochimica Acta vol 49 no 9-10 pp 1483ndash1490 2004

[13] G Duan C Zhang A Li X Yang L Lu and X Wang ldquoPrepa-ration and characterization of mesoporous zirconia madeby using a poly (methyl methacrylate) templaterdquo NanoscaleResearch Letters vol 3 no 3 pp 118ndash122 2008

[14] M Ravi S Bhavani K Kiran Kumar and V V R NarasimahaRao ldquoInvestigations on electrical properties of PVPKIO4polymer electrolyte filmsrdquo Solid State Sciences vol 19 pp 85ndash93 2013

[15] P K Karahaliou N Xanthopoulos C A Krontiras and S NGeorga ldquoDielectric response and ac conductivity analysis ofhafnium oxide nanopowderrdquo Physica Scripta vol 86 no 6Article ID 065703 2012

[16] C Tang K Hackenberg Q Fu P M Ajayan and H ArdebilildquoHigh ion conducting polymer nanocomposite electrolytesusing hybrid nanofillersrdquo Nano Letters vol 12 no 3 pp 1152ndash1156 2012

[17] C M Mathew M Shanthi and S Rajendran ldquoThermal andimpedance studies of poly(vinylidene chloride-co-acryloni-trile)-based gel polymer electrolyterdquo Journal of ThermoplasticComposite Materials 2013

[18] N Rajeswari S Selvasekarapandian S Karthikeyan et alldquoConductivity and dielectric properties of polyvinyl alcohol-polyvinylpyrrolidone poly blend film using non-aqueousmediumrdquo Journal of Non-Crystalline Solids vol 357 no 22-23pp 3751ndash3756 2011

[19] B A Howell ldquoThe application of thermogravimetry for thestudy of polymer degradationrdquo Thermochimica Acta vol 148pp 375ndash380 1989

[20] H Cheng C Zhu B HuangM Lu and Y Yang ldquoSynthesis andelectrochemical characterization of PEO-based polymer elec-trolytes with room temperature ionic liquidsrdquo ElectrochimicaActa vol 52 no 19 pp 5789ndash5794 2007

[21] R A Wessling D S Gibbs P T DeLassus B E Obi and B AHowell ldquoVinylidene chloride monomer and polymersrdquo inKirk-Othmer Encyclopedia of Chemical Technology vol 24 pp 882ndash923 John Wiley amp Sons New York NY USA 4th edition 1997

[22] A Leszczynska J Njuguna K Pielichowski and J R Baner-jee ldquoPolymermontmorillonite nanocomposites with improvedthermal properties Part I Factors influencing thermal stabilityand mechanisms of thermal stability improvementrdquo Ther-mochimica Acta vol 453 no 2 pp 75ndash96 2007

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


2 Materials and Methods

Poly(vinylidene chloride-co-acrylonitrile) (PVdC-AN Avg119872119908

150000 Aldrich USA) poly(methyl methacrylate)(PMMA Avg 119872

119908

120000 Aldrich USA) plasticizer ethy-lene carbonate EC (Alfa Aesar India) and electrolyte saltlithium tetrafluoroborate (LiBF

4

Aldrich USA) were usedas received All electrolyte membranes were prepared bysolution casting technique Appropriate weights of PVdC-AN PMMA and LiBF

4

were dissolved separately in theorganic solvent tetrahydrofuran (THFMerck India) at roomtemperature The polymer and salt solutions were mixed andthen stirred continuously for 12 h to obtain a homogeneoussolution The plasticizer ethylene carbonate was added to thepolymer solution with ratios 20 40 60 and 80wt Theobtained homogeneous highly viscous solution was alloweddegassing to remove air bubbles and cast onto the well-cleaned petri-dishes to get the desired thin film membranesThen the solvent was allowed to evaporate slowly at 60∘Cfor about 6 h using vacuum oven Finally the harvested elec-trolyte membranes were analysed using various techniquesThe PVdC-ANPMMA blend electrolyte membrane with80wt ethylene carbonate could not form a freestandingfilm and was in the form of a gel at room temperature Themembranes with 20 40 and 60wt of EC were denoted asR1 R2 and R3 respectively

The X-ray diffraction patterns were recorded with acomputer controlled Xrsquopert PRO PANalytical diffractome-ter in the scanning range 2120579 = 10 to 80∘ using Cu-K120572(wavelength 120582 = 1541 A) radiation as a source The FourierTransform Infrared (FT-IR) spectra of the samples wererecorded withThermofisher Nicolet iS10 FT-IR Spectrometerin the range of 4000ndash400 cmminus1 in the transmittance modeThe electrochemical analysis of the polymer electrolytes wascarried out by sandwiching the electrolyte film betweenstainless steel blocking electrodes using 120583-Autolab Type-IIIPotentiostatGalvanostat in the frequency range 1Hzndash1MHzThe measurements were taken between 303K and 353KThevalue of bulk resistance 119877

119887

was found to be the intercept onthe 119909-axis of the impedance plot The conductivity (120590) wascalculated using

120590 =119897

119877119887

119860 (1)

where 119897 is the thickness of the polymer electrolyte film 119877119887

isthe bulk resistance and 119860 is the surface area of the polymerelectrolyte film [7]

All the polymer complexes were subjected to thermalanalysis which was carried out using Perkin Elmer Pyris-6 TGDTA Analyzer The thermogravimetric curves wererecorded in nitrogen atmosphere from room temperatureto 600∘C The heating rate was 10∘Cmin From TG plotstemperature of maximum process rate temperature at theend of decomposition and weight loss were determined

3 Results and Discussion

31 Structural Analysis Structural analysis of the preparedpolymer complexes was carried out using X-ray diffraction

PVdC-AN

PMMA

R1

R2

R3

10 20 30 40 50 60 70 80

Inte

nsity

(au

)

(101

)

(020

) (202

)(0

22)

(311

)

Angle 2120579 (deg)

LiBF4

Figure 1 XRD patterns of PVdC-ANPMMAECLiBF4

mem-branes

method The diffraction pattern of PVdC-ANPMMA-ECLiBF

4

based membranes is shown in Figure 1The graphsshow that PVdC-AN exhibits semicrystalline peaks at angles2120579 = 4025 4676 and 6794∘ and PMMA shows an amor-phous natureThe intense peaks of LiBF

4

in Figure 1 at angles2120579 = 187 267 281 377 446 528 and 5793∘ reveal the crys-talline nature of the ionic salt All of these crystalline peaks arefound to have disappeared when the polymer plasticizer andsalt were mixed togetherThus XRD patterns of the preparedpolymer membranes in Figure 1 reveal the amorphous naturewhich is essential for a polymer electrolyte The interactionbetween the polymer atoms plasticizer and lithium ionsdisturbed the polymer network which leads to a decrease incrystallinity The amorphous nature of complexes indicatesthat the lithium salt is not crystallized in the film but rathermolecularly dispersed within the polymer in the presenceof EC With the increase in the content of EC complexesbecame completely amorphous without any trace of diffrac-tion halos It is known that high intensity diffraction peaksare associated with high crystallinity and broader diffractionhumps for their semicrystallineamorphous nature Hencethe broadening of diffraction peaks reveals the enhancementof the amorphous nature of PVdC-ANPMMALiBF

4

ECpolymer electrolyte membranes In addition the absencesof diffraction peaks of both polymer and salt in preparedcomplexes reveal the good miscibility of polymer and saltwith plasticizer at the molecular level These results suggestthat the incorporated lithium salts were dissolved in theamorphous region of polymer in the presence of plasticizerand the ionic conductivity of polymer electrolyte given by theamorphous phase of the complex [8]

32 Functional Group Analysis The FT-IR spectra of PVdC-ANPMMA electrolyte membranes are shown in Figure 2The spectra of pure samples such as PVdC-AN PMMA EC


4000 3500 3000 2500 2000 1500 1000 500

R3

PVdC-AN

C-H

C=O

C-HPMMA O=H

Tran

smitt

ance

()

R1

R2

EC

C=O


CequivN



membranes

and LiBF4


2



2


R1R2R3

1 10 100 1k 10k 100 k 1M10minus9

10minus8

10minus7

10minus5

10minus6

120590998400 (S

cmminus

1 )

Frequency f (Hz)


4

membranes

BF4


4


3





00

303K313K323K

333K343K353K

Z998400 (Ohm)

minusZ998400998400

(Ohm

)

10k 20k 30k 40k 50k

10k

20k

30k

40k

50k






4





28 29 30 31 32 33 34

R1R2R3

minus90

minus80

minus70

minus60

minus50

minus40

minus30

1000T (Kminus1)

(S cm

minus1 )

log120590


4


0



119891








0

500

1000

1500

2000

2500

R1R2R3


120576998400

(a)

0

1000

2000

3000

4000

5000

6000


1 10 100 1k 10k 100 k 1M

120576998400998400

(b)





119903


119894


0 100 200 300 400 5000

20

40

60

80

100R2

R3R1

Wei

ght (

)

R1R2R3

Temperature (∘C)





2


4 Conclusion





Acknowledgment


References








4




2






4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


4000 3500 3000 2500 2000 1500 1000 500

R3

PVdC-AN

C-H

C=O

C-HPMMA O=H

Tran

smitt

ance

()

R1

R2

EC

C=O


CequivN



membranes

and LiBF4


2



2


R1R2R3

1 10 100 1k 10k 100 k 1M10minus9

10minus8

10minus7

10minus5

10minus6

120590998400 (S

cmminus

1 )

Frequency f (Hz)


4

membranes

BF4


4


3





00

303K313K323K

333K343K353K

Z998400 (Ohm)

minusZ998400998400

(Ohm

)

10k 20k 30k 40k 50k

10k

20k

30k

40k

50k






4





28 29 30 31 32 33 34

R1R2R3

minus90

minus80

minus70

minus60

minus50

minus40

minus30

1000T (Kminus1)

(S cm

minus1 )

log120590


4


0



119891








0

500

1000

1500

2000

2500

R1R2R3


120576998400

(a)

0

1000

2000

3000

4000

5000

6000


1 10 100 1k 10k 100 k 1M

120576998400998400

(b)





119903


119894


0 100 200 300 400 5000

20

40

60

80

100R2

R3R1

Wei

ght (

)

R1R2R3

Temperature (∘C)





2


4 Conclusion





Acknowledgment


References








4




2






4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

303K313K323K

333K343K353K

Z998400 (Ohm)

minusZ998400998400

(Ohm

)

10k 20k 30k 40k 50k

10k

20k

30k

40k

50k






4





28 29 30 31 32 33 34

R1R2R3

minus90

minus80

minus70

minus60

minus50

minus40

minus30

1000T (Kminus1)

(S cm

minus1 )

log120590


4


0



119891








0

500

1000

1500

2000

2500

R1R2R3


120576998400

(a)

0

1000

2000

3000

4000

5000

6000


1 10 100 1k 10k 100 k 1M

120576998400998400

(b)





119903


119894


0 100 200 300 400 5000

20

40

60

80

100R2

R3R1

Wei

ght (

)

R1R2R3

Temperature (∘C)





2


4 Conclusion





Acknowledgment


References








4




2






4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






0

500

1000

1500

2000

2500

R1R2R3


120576998400

(a)

0

1000

2000

3000

4000

5000

6000


1 10 100 1k 10k 100 k 1M

120576998400998400

(b)





119903


119894


0 100 200 300 400 5000

20

40

60

80

100R2

R3R1

Wei

ght (

)

R1R2R3

Temperature (∘C)





2


4 Conclusion





Acknowledgment


References








4




2






4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



2


4 Conclusion





Acknowledgment


References








4




2






4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




4





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article structural and electrochemical...

Documents