Facile Green Strategy for Micro/Nano Structured Conducting Polyaniline-Clay Nanocomposite via...

Facile Green Strategy for Micro/Nano StructuredConducting Polyaniline-Clay Nanocomposite via TemplatePolymerization Using Amphiphilic Dopant, 3-PentadecylPhenol 4-Sulphonic Acid

J. D. SUDHA, V. L. REENA, C. PAVITHRAN

Chemical Sciences Division, Regional Research Laboratory CSIR, Thiruvananthapuram 695019, India

Received 9 January 2007; accepted 20 June 2007DOI: 10.1002/polb.21273Published online in Wiley InterScience (www.interscience.wiley.com).

ABSTRACT: Novel self-assembled nano/microstructured conducting PANICN was pre-pared by in situ intercalative emulsion polymerization of aniline in aqueous dispersionof clay using bifunctional amphiphilic dopant, 3-pentadecyl phenol-4-sulphonic acid(PDPSA) derivable from renewable resource. X-ray diffraction and scanning electronmicroscopy (SEM) studies revealed the formation of monolayer of protonated PANIintercalated nanoclays with template polymerized self-assembled micro/nanostruc-tured protonated PANI. Nano/micro structured PANIs were formed by the supra mo-lecular self-assembling of the inter-chain hydrogen bonding, inter-plane phenyl stack-ing and electrostatic layer by layer self-assembling (ELBS) between polarized alkylchains present dopant anions and were manifested using fourier transform infra redspectroscopy and differential scanning calorimetry. On the basis of the results, struc-ture-directing effect of ‘anilinium salt micelle’ was schematically illustrated in this ar-ticle. VVC 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2664–2673, 2007

Keywords: clay; conducting polymer; intercalating agent; micelles; morphology;nanocomposite; renewable resource; self assembling

INTRODUCTION

Polyaniline-clay nanocomposite (PANICN) repre-sents a new class of molecular composites withdiverse electrical, optical, mechanical, and ther-mal properties.1–3 PANI has been widely studiedbecause of simple preparation, good thermal sta-bility, environmental stability, and structure ver-satility. Clays are abundantly available naturalmaterials having high aspect ratio, high surfacearea, and are easy to modify. PANICN consistsof multilayered sandwich like elements in whichPANI chains are sandwiched between nano-claylayers.4

They are prepared by different strategies forpotential applications in nano-electronic devices,optical applications, rechargeable batteries, elec-tromagnetic interference shielding, and also formitigating electrical charge build up in lightweight structures.5–9 A promising way to controland enhance the PANI bulk properties is to organ-ize the polymer chains in the nanometer regime.10

Some ways to achieve nano-structured PANIinvolves the synthesis in micellar media,11,12

template-guided polymerization using poroussurfaces.13–15 Template provides a necessarytype of local environment when pH and chargedensity near the template molecules controlsthe shape of PANI to be obtained. Anothermethod is self-assembly based on selective con-trol of non covalent interaction (hydrogen bond-ing, van der Waals forces, p–p stacking, metal

Correspondence to: J. D. Sudha (E-mail: [email protected])

Journal of Polymer Science: Part B: Polymer Physics, Vol. 45, 2664–2673 (2007)VVC 2007 Wiley Periodicals, Inc.

2664

coordination or dispersive forces) that provides apowerful tool for the creation of well definedstructures.16,17 Mesomorphic behavior of hydro-gen bonded self-assembled complexes of methylsulphonic acid (MSA), polyvinyl pyridine (PVP),and 3-PDP (3-pentadecyl phenol), which is thestarting material for the preparation of PDPSA,was reported by Ikkala and Ten.18

Bentonite is an interesting inorganic hostmaterial used to prepare PANICN because ofits small particle size, capacity to swell andexchange cations for intercalation.19 This is oneof the most abundant naturally occurring 2:1phyllosilicate having layered structure in whichthin layers of aluminum silicate organize them-selves in a parallel fashion to form stacks with aregular van der Waals gap in between themcalled interlayer spacing or gallery. Substitutingions of lower charge for higher charge in both theoctahedral (e.g., Mg21 replacing Al31) and tetra-hedral (e.g., Al31 replacing Si41) sheets producesnegatively charged layers. In the interlayerregion there exists Na1 and Ca21, which can bereplaced with the alkyl ammonium or alkylphos-phonium ions rendering the clay organophilic.20

It was reported earlier that PANICN could beprepared by in situ intercalative emulsion poly-merization of aniline using dodecyl benzene sul-phonic acid (DBSA) as intercalating agent cumfunctionalized dopant.21 The presence of bothhydrophobic (alkyl) and hydrophilic (��SO3H)groups in DBSA, enables it to function as a sur-factant for reducing the inter gallery interactionand promoting the expansion of inter galleryspace. After intercalation of the anilinium ion,the extrinsic initiator ammonium persulphate(APS) can enter and initiate polymerization forgetting protonated PANI chain confined PAN-ICNs. Structurally, two kinds of PANICNs can beisolated: (i) intercalated nanocomposite wherepolymer chains are between the clay layers and aregular repeating distance can be observed; (ii)exfoliated nanocomposite where clay stacks aredelaminated forming individual layers and dis-persed within the PANI chains. The formation ofintercalated and/or exfoliated nanocompositedepends on clay/aniline/dopant ratio.19

Apart from the reported amphiphilic dopantsfrom the families of sulphonic acids,22 phos-phonic acids23 as well as phosphoric acid es-ters,24 we identified few similar molecular sys-tems derivable from 3-PDP,25 which is obtainedfrom cashew nut shell liquid. The presence ofboth hydrophobic (alkyl) and hydrophilic

(��O3H/��HPO4) groups enables it to function asan intercalating agent cum dopant similar toDBSA. It has been reported earlier that the mor-phology and physical properties of the nano-structured PANICN could be controlled by thesynthetic conditions, structure and amount ofthe dopants.26

Recently we reported the formation of nano/micro structured PANICN using pentadecyl phe-nyl phosphonic acid which is a monofunctionalamphiphilic dopant having phosphoric acidgroup meta to the alkyl chain.27 In this study,we report the studies on the synthesis and prop-erties of micro/nanostructured PANICNs using3-pentadecylphenol-4-sulphonic acid as interca-lating agent cum dopant which is a bifunctionalmolecule having sulphonic acid group ortho tothe alkyl chain and para to the hydroxyl group.On the basis of the SEM, XRD, DSC, and FTIRstudies, the mechanism of the formation ofnano/microstructured PANI is schematicallyillustrated by the ‘anilinium salt micelle’ tem-plate guided polymerization. Effect of composi-tional variation of aniline/dopant/clay on themorphology and other physical properties ofPANICNs are also discussed in this article.

EXPERIMENTAL

Materials

Aniline monomer (99.5% pure, Ranbaxy Chemi-cals, Bombay) was distilled under reduced pres-sure, APS, methyl alcohol (s.d. fine chem limited,Bombay, India) were used without further purifi-cation. Bentonite clay with cation exchangecapacity of 55 meq/100 g and a mean chemicalformula of (Na, Ca)0.33(Al1.67Mg0.33)Si4O10(OH)2nH2O (Loba Chemie, Bombay, India). Prior touse it was washed by saturated sodium chloridesolution many times and size fractionated toobtain Na-bentonite free of impurities. 3-penta-decyl phenol-4-sulphonic acid (PDPSA) was pre-pared from 3-pentadecyl phenol (cardanol),obtained by the double distillation of cashew nutshell liquid (cashew export promotion council,India) at 3–4 mmHg at 230–235 8C.

Instrumentation

UV-Vis absorption spectra of the PANI and PAN-ICN were studied by coating thin films of thesample on a glass plate and recorded the spectra

TEMPLATE POLYMERIZATION USING AMPHIPHILIC DOPANT 2665

Journal of Polymer Science: Part B: Polymer PhysicsDOI 10.1002/polb

using UV-Vis spectrophotometer [Shimadzumodel 2100] in the range of 300–1100 nm.

Elemental analysis was performed using Per-kin-Elmer elemental analyzer. PANI and PAN-ICNs were dispersed in potassium bromide andcompressed into pellets to record FTIR spec-trum. The measurements were made with afully computerized Nicolet impact 400D FTIRspectrophotometer. All spectra were correctedfor the presence of moisture and carbon dioxidein the optical path. 1H NMR spectrum wasrecorded in Bruker 300 MHz FTNMR equippedwith ASPECT-3000 computer after dissolvingthe sample in trifluoroacetic acid and lockingwith CDCl3 and tetra methyl silane as internalstandard.

The interlayer distance of the nanoclay andformation of self-assembled structures of sam-ples were analysed using powder X-ray diffrac-tometer (Philips X0pert Pro) with CuKa radiation(k � 0.154 nm) employing X0celarator detectorand monochromator at the diffraction beam side.Powder samples were used employing standardsample holder. Averaged 2h was used with the 2hresolution of 0.0028 from 28 to 108.

Electrical conductivity (rdc) of uniform sizedpressed pellets at 308C was measured using thestandard spring loaded pressure contact fourprobe method supplied by Scientific Equipment,Roorkee (India). The conductivity (r0) was calcu-lated using Van der Pauw relation

r0 ¼ ln 2=pd

� �I=V

� �;

where d is the thickness of the film.Morphological studies of PANICNs pelletised

powder samples were studied using scanningelectron microscope (SEM, JEOL make, modelJSM 5600 LV) at 15 kV accelerating voltage.

DSC scans were performed using DupontDSC 2010 differential scanning calorimeterattached to Thermal Analyst 2100 data solutionunder nitrogen atmosphere at a heating rate of10 8C/min.

Synthesis of 3-pentadecyl phenol-4-sulphonic acid

Ten gram of 3-PDP was mixed with 5 mL con-centrated H2SO4 in a 100-mL round bottomedflask using magnetic stirring at 80 8C for 2 hand 110 8C for 1 h. It was then dissolved in ice-cold water and washed with n-butanol. Adjustedthe pH to 7. Filtered, washed, and then acidified

to get the PDPSA. Further dried in a vacuumoven at 80 8C. Color and appearance—colorlesspowder. Yield-80%. Chemical structure of thePDPSA was characterized by elemental analysis,FTIR and 1H NMR. Mol. formula C21H39SO4

Elem. anal C: obs 64.9% cal 65.1% H: obs 10.0cal 10.07% S: obs 8.3% cal 8.2%. In FTIR spec-tra, the m (max) 2919, 2841, 1469– (CH2��) n,1605, 694 (Ar), 1227 (CO), 1305, 1195 (SO), 1032cm�1 (SO3).

1H NMR (CDCl3, ppm): d 0.8–0.9(3H, t, CH2��CH3), 1.25 (26H, bs, ��CH2��) n,2.8 (2H, t, Ph��CH2��) n, 5.7 (1H, bs, OH), 6.8–6.9 (3H, m, Ar), 7.0 (1H, d, ArC-5).

Preparation of PANI and PANICN

The general procedure for preparing PANI andPANICN are as follows. PANICN was preparedby the in situ intercalative emulsion polymeriza-tion method.21 About 2.5 g of bentonite wastaken in a three-necked flask fitted with a me-chanical stirrer and reflux condenser. Then dis-persed in 200 mL of deionized water by heatingand stirring at 80 8C for 3 h. An aqueous solu-tion of aniline 2.5 g (0.029 mol) containing 11.04g (0.029 mol) of 3-PDPSA was then added dropwise to the clay dispersion. Heating and stirringcontinued for 2–6 h. The mix was cooled downto 0 8C by keeping in an ice bath and a solutionof APS (0.03 mol) dissolved in 50 mL water wasadded drop wise to initiate the polymerization.Reaction continued for 3–4 h. PANICN was iso-lated by precipitating from methanol. It wasthen filtered, washed with deionized water,finally with methanol and then dried in a vac-uum oven for 3 days at 60 8C.

Experiments were performed with differentratios of aniline and 3-PDPSA. PANI-PDPSAwithout clay was also prepared for comparison.

RESULTS AND DISCUSSION

Preparation of PANI-PDPSA and PANICN-PDPSA

PANICN was prepared by the in situ inter-calative emulsion polymerization of aniliniumsulphonate complexes of PDPSA, in aqueous dis-persion of bentonite using APS as oxidant initia-tor21 as shown in Scheme 1. Experiments wereperformed with and without the presence of clayand also with different ratios of aniline toPDPSA. The induction period and polymeriza-tion time were recorded from the beginning of

2666 SUDHA, REENA, AND PAVITHRAN


Scheme 1. Preparation of polyaniline and polyaniline clay nanocomposite.

Scheme 2. Formation of self-assembled micro/nanostructured PANI and PANICNS.



the oxidant addition to the reaction mixtureuntil the color turned pale blue and dark green,respectively. PANI forms by oxidative radical po-lymerization of anililinium salt. When a newmonomer is added to the polymer chain, it isreduced and reoxidized through the medium. Atthe beginning, only the totally oxidized non con-ducting form of the PANI, the pernigranilineform is present (copper tint color).28 Polymeriza-tion continues and become conducting PANI(emeraldine green form) of the doped PDPSA.At this point, oxidation potential becomes slowand polymerization stops. In presence of clay,the induction period appeared to be longer thanin bulk polymerization because of the confine-ment of the reactants in the clay galleries.

UV-Vis Spectra

UV-Vis spectral technique is a very sensitivetool for studying the nature of PANI protonationand will show obvious difference between PANI-PDPSA and PANICN-PDPSA. The UV-Vis spec-tra of the PANI-PDPSA, PANICN-PDPSA areshown in Figure 1(a,b). PANI-PDPSA exhibitedtwo broad absorption maxima in the range of340–370 nm and 700–720 nm. The initialabsorption peak can be assigned as the p-p*transition in the reduced unit of polyaniline.29

The strong absorption peak emerges at �700nm is due to the head to tail coupling of anili-nium radical cations of the PANI-emeraldine

salt.30 But in the PANICN-PDPSA, this peakshowed a red shift which appeared as a broadabsorption band (called ‘‘free-carrier tail’’) in thenear infra red region. It is consistent with thedelocalization of electrons in the polaron bandpromoted by the extended conformation of thedoped PANI chains inside the nano claylayers.31

FTIR Spectra

FTIR spectral technique can be used for study-ing the interactions between the dopant anionand the PANI chains and also interactionbetween PANI chains and clay surface. FTIRspectra of pristine bentonite, PANI-PDPSA,PANICN-PDPSA are shown in Figure 2(a–c).The characteristic bands corresponding to pris-tine bentonite are 1023 [m (Si��O)], 911[d(Al��OH)] and 525 cm�1 (m (Si��O��Al)].32 Thevibration bands (C¼¼C stretching deformation ofthe quinoid33 shifted from 1590 to 1572 cm�1

and that of the benzenoid ring from 1502 to1485 cm�1) in PANI-PDPSA indicated longereffective conjugation lengths.34 However, from acloser look at the spectra that the band at 1295cm�1 for the PANI-PDPSA assigned as thestretching vibration of C��N [m (C��N)], is sig-nificantly shifted to 1301 cm�1 for PANICN-PDPSA as shown in Figure 2. This frequency

Figure 1. (a) PANI-PDPSA. (b) PANICN-PDPSA.[Color figure can be viewed in the online issue, whichis available at www.interscience.wiley.com.]

Figure 2. FTIR spectra of pristine (a) bentonite, (b)PANICN-PDPSA, (c) PANI-PDPSA.



shift of m (C��N) observed in PANICN-PDPSA iscaused by the interaction between PANI and thebasal surface of nano clay (i.e., N��H. . .O). Theabsorption bands around 3423, 3230, and 2300–2800 cm�1, reflect the organization of PANIchains by hydrogen bonded interaction involvingNH and NH1 groups.35 The bands at 1040 and506 cm�1 can be assigned to the absorption ofthe sulphonate anion.36

XRD

XRD is an efficient analytical tool to probe theextent of intercalation in polymer-clay nanocom-posite. During intercalation, the PANI- dopantchains get confined in the inter-clay plateletsand the distance between the stacked silicateplatelets increases in various ways dependingon the amount, conformation of the confinedprotonated PANI chains, layer charge density,and functionality of the intercalating agents.37–39

The d-spacing of the nanocomposite was calcu-lated from the angular positions 2h of theobserved <001> reflection peaks based on theBragg’s formula nk ¼ 2d sinh, where k is thewavelength of the X-ray beam and h is the dif-fraction angle. XRD patterns of bentonite,PANI-PDPSA, PANICN-PDPSA1, PANICN-PD-PSA2, PANICN-PDPSA3, and PANICN-PDPSA4are shown in Figure 3(a–f) respectively and thedetails are given in Table. The diffractionpattern of PANI-PDPSA exhibited two sharpdiffraction peaks at 2h ¼ 3.1o and 7.98 (d-spacingof 28.38 and 11.17 A) corresponding to the self-assembled protonated PANI-PDPSA layers.Similar observations were reported for theself-assembled layered structure of protonatedPANI-DBSAs with d-spacing of 27 A.40 The rel-atively narrow and intense diffractogram canbe attributed to the ordered structure inducedby the hydrogen bond interaction betweenPANI layers with the hydroxyl group ofPDPSA, as suggested for the supramolecularstructures formed from hydrogen-bonded com-plexes of polyvinyl pyridine (PVP) with MSAand 3-PDP.41

Bentonite showed d001 reflection at 2h ¼ 7.268corresponding to an interlayer spacing of 12.1 A.The XRD pattern of PANICN-PDPSA1 showedtwo peaks at 2h ¼ 2.518 and 4.758 correspondingto d- spacing of 35.19 A, 18.58 A. The latterreflection is due to shifting of d001 plane of theclay. Intercalation of mono layer of PANI pro-duces an enhancement of interlayer spacing ofthe layered material in the range of 4–9 A,depending on the dimension of the dopantanion.42–44 Bentonite has aluminium silicatelayer thickness corresponding about 9.6 A andinterlayer gap of 2.5 A due to the presence ofhydrated cations, exchangeable with organic cat-ions. Thus, in the present system, enhanance-ment of interlayer spacing by 9 A is occurred byintercalation of PANI–PDPSA monolayer. Thisvalue is close to the dimension of PANI-PDPSA

Figure 3. (a) Bentonite, (b) PANI-PDPSA, (c) PAN-ICN-PDPSA1, (d) PANICN-PDPSA2, (e) PANICN-PDPSA3 and (f) PANICN-PDPSA4.



doped polyaniline lying perpendicular to theplane of the clay surface. However, intensity ofthis peak decreases with increasing amount ofdopant and vanishes for aniline:dopant ratio of1:2 because of the increase in size of the micelleconcentration and disordering of the clay layers.

The second peak observed at the lower angle(2h ¼ �1.9o) with d-spacing of 45 A arises fromthe layer thickness of self-assembled PANI-PDPSA, engulfed on the clay surfaces. Thethickness varies with the amount of the dopant.PANICN-PDPSA1, PANICN-PDPSA2, PANICN-PDPSA3, and PANICN-PDPSA4 exhibited layerthickness in the order 35, 37, 45 and 46.5 Awith aniline:dopant molar ratio of 1:05, 1:1,1:1.5, and 1:2, respectively. It may be interest-ing to note that the self-assembled PANI-PDPSA in PANICN showed higher layer thick-ness than for PANI-PDPSA without clay (27 A).This indicates the formation of the modifiedPANI layered structures engulfed on clay par-ticles, as shown in Scheme 2. Formation ofsuch self-assembled structures by interaction ofalkyl chain substituted organic molecules hav-ing polar head group with clay surface wasreported by Brindley.45

SEM

SEM studies were carried out with the pelletizedpowder samples. The micrographs of protonatedPANI and PANICNs are shown in Figure 4. It isobserved that the microstructure of PANICNs ishighly dependent on the aniline/dopant ratio.Micrograph of PANI-PDPSA [Fig. 4(a)] revealedthe formation of hexagonal/tetragonal crystalli-tes. PANICN-PDPSA1 with aniline/dopant ratio1:0.5, showed nano-structured rods appeared tobe originating and growing out of the clay inter-layer/surface [Fig. 4(c)]. When the aniline/dopantratio is increased to 1:2, micro-structured rods/strips [Fig. 4(b)] were observed, possibly due toaggregation of the nano-structured rods. Figure4(d) shows the initial stage of the nanostructureformation of PANICN-PDPSA4. It shows thatnano-size rod shaped particles of PANI-PDPSAare formed in the beginning.

The micelle formed by the hydrophilic anilinewith the amphiphilic sulphonic acid will play arole in forming templates on the clay surface,which facilitate polymerization of anilinium saltin an ordered fashion. Hence the micro/nano-structured materials observed in PANI-PDPSAand PANICN-PDPSA can be suggested through

Figure 4. (a) PANI-PDPSA, (b) PANICN-PDPSA4, (c) PANICN-PDPSA2, (d)PDPSA1�An micelle containing nanoparticles of PANI.



‘‘micelle’’ guided template polymerization asshown in Scheme 2. PDPSA is built with twohydrophilic groups (SO3

� and OH) lying para tothe benzene ring with long alkyl chain meta to the��OH group and para to the ��SO3H. When ani-line is mixed with PDPSA, PDPSA1�An salt isformed by an acid–base reaction. Because the sur-face composed of ��SO3H, NH, OH groups, phenylrings and partially polarized long alkyl chain ofanions, they organize to form micelles and willprovide a wide variety of active sites for nuclea-tion.46,47 The free aniline can diffuse into thecenter of the micelles to form a core which uponpolymerization produce nanosize rods. Thesenanorods aggregate to form nano/micro structuredrods/strips through interactions including hydro-gen bonding, TT–TT interactions and ELBLS.48

DSC

Thermal phase transition changes of PANI andPANICNs were studied by DSC at a heatingrate of 10 8C/min in nitrogen atmosphere andthe DSC curves of PANI-PDPSA, PANICN-PDPSAs are depicted in Figure 5(a–d). PANI-PDPSA exhibited a broad transition tempera-ture while PANICN-PDPSAs exhibited twobroad endotherms between 140–170 8C. Onheating, PANICNs undergo change in energythat can arise from two factors. First transitionarises from the conformational change becauseof the hydrogen-bonded interaction of the proto-nated PANI-PANI chains.49 Second transitionmight be from the guest-host interaction bet-ween protonated PANI chains and the claylayer.50 The latter observation was further con-firmed by FTIR.

Conductivity

Conductivity data of PANI-PDPSA and PAN-ICN-PDPSAs are listed in Table 1. Conductivityof PANI-PDPSA is measured as 8.2 3 100 S/cm.PANICN-PDPSA showed conductivity in theorder of 7.11 3 10�2, 1.18 3 10�1, 4.3 3 100,and 5.11 3 100 S/cm when the [aniline]:[PDPSA]molar ratio varied from 1:0.25, 1:5, 1:1, and 1:2,respectively. Results showed that the conductiv-ity of PANICN is controlled by two factors. InPANICN, the clay layers interrupt the effectivedoping and induce the weak inter-chain interac-tion. This causes relatively low conductivity inPANICN PDPSAs compared with PANI-PDPSA.As the concentration of dopant increases, theextent of protonation also increases and thenumber of polarons (radical cations i.e., chargecarriers) increases. Conductivity can be exp-ressed as r ¼ nel, where ‘e’ is the electroniccharge, ‘n’ is the density of the charge carriers

Figure 5. (a) PANI-PDPSA, (b) PANICN-PDPSA3,(c) PANICN- PDPSA2, and (d) PANICN- PDPSA1.

Table 1. Experimental Details of Conductivity and XRD Data of PANI-PDPSA, PANICN-PDPSA

Sample Ratio of Aniline:Dopant Yield (%) Conductivity (S/cm)

XRD Results

d-Spacing Angle (2Y)

PANI-PDPSA 1:1 75 8.2 3 100 28.38, 11.17 3.18, 7.98PANICN-PDPSA1 1:0.5 55 7.17 3 10�2 35.19, 18.58 2.518, 4.758PANICN-PDPSA2 1:1 69 1.18 3 10�1 37.92, 18.71 2.338, 4.728PANICN-PDPSA 3 1:1.5 66 4.3 3 100 45.82, 18.9 (sharp) 1.938, 4.668PANICN-PDPSA 4 1:2 58 5.11 3 100 46.5, 18.9 (sharp) 1.98, 4.668Bentonite – – – 12.1 7.268



and ‘l’ is the mobility of the charge carrierrespectively. Thus the conductivity increaseswith the increase in concentration of dopant. Itis clear from the above results that with 15–20%loading of clay in PANICN exhibited conductiv-ity in the range of bulk PANIs because of thedelocalization of polaron band with the delocal-ized electron cloud as observed in UV-Vis spec-tra. These results are reminiscent with theobservations made by other researchers.5

CONCLUSIONS

In conclusion, we repot the structure-directingeffect of PDPSA derived from renewableresource for the formation of nano/microstruc-tured rods/strips both in PANI and PANICN. Itwas found that the morphology and size of thePANI strongly depend on the ratio of aniline toPDPSA. On the basis of the results obtainedfrom XRD and SEM images, we suggest thatthe self–assembled ‘‘aniline1�PDPSA rod-likemicelles’’ are responsible for directing the forma-tion of oriented PANI nanoparticles and PANInano/microstructures are made up of nanopar-ticles. Conductivity measurement showed thatwith 15–20% loading of clay in PANICNs exhib-ited conductivity in the range of bulk PANIbecause of the extended conformation of the con-fined PANI chains. The physical interactionsbetween the PANI chains and between the inter-calated PANI chain and silicate layer weremanifested through studies by FTIR and DSC.To conclude, PDPSA derived from renewableresource is a low cost dopant cum intercalatingagent which can be successfully used for thepreparation of well ordered electrically conduct-ing micro/nano structured polyaniline-clay nano-composite.

The authors are very grateful to Council of Scientificand Industrial Research (CSIR, India) for the finan-cial support from the Task force fund (COR 004) andISRO respond programme (GAP 109439). They arealso thankful to Mr. P. Prabhakar Rao, Scientist, Mr.P. Guruswamy and Mr. P. Mukundan for all the ana-lytical help and useful discussions.

REFERENCES AND NOTES

1. (a) Enzel, P.; Bein, T. Chem Mater 1992, 4, 819;(b) Pillion, J. E.; Thompson, M. E. Chem Mater1991, 3, 777; (c) Nazar, L. F.; Zhang, Z.; Zinkweg,

D. J Am Chem Soc 1992, 114, 6239; (d) Kanatzi-dis, M. G.; Wu, C.; Marcy, H. O.; Kannewurf, R.J Am Chem Soc 1989, 111, 4139.

2. Becker, O.; Cheng, Y.-B.; Varley, R. J.; Simon, G.P. Macromolecules 2003, 36, 1616.

3. (a) Zerda, A. S.; Lesser, A. J. J Polym Sci Part B:Polym Phys 2001, 39, 1137; (b) McCann, G. F.;Millar, G. J.; Bowmaker, G. A.; Cooney, R. P.J Chem Soc Faraday Trans 1995, 91, 4321.

4. (a) Cardin, D. J Adv Mater 2002, 5, 553; (b) Thia-garajan, M.; Samuelson, L. A.; Kumar, J.; Cholli,A. L. J Am Chem Soc 2003, 125, 11502; (c)Huang, J.; Kaner, R. B. J Am Chem Soc 2004,126, 851.

5. (a) Feng, B.; Su, Y. J Mater Sci Lett 2001, 20,293; (b) Chang, T. C.; Ho, S. Y. J Chin Chem Soc1992, 39, 209; (c) Frisch, H. L.; Xi, B.; Yang, N. L.High Perform Polym 2000, 12, 543; (d) Kim, B.H.; Jung, J. H.; Kim, J. W. Synth Met 2001, 117,115; (e) Kim, B. H.; Jung, J. H.; Kim, J. W. SynthMet 2001, 121, 1311.

6. Hotta, S.; Paul, D.R. Polymer 2004, 45, 7639.7. (a) Kim, B. H.; Jung, J. H.; Kim, J. W.; Choi, H.

J.; Joo, J. Synth Met 2001, 117, 115; (b) Kim, B.H.; Jung, J. H.; Kim, J. W.; Choi, H. J.; Joo, J.Synth Met 2001, 121, 1325; (c) Kim, J. W.; Kim,S. G.; Choi, H. J.; John, M. S. Makromol RapidCommun 1999, 20, 450; (d) Segal, E.; Aviel, G.;Narkis, M. Prog Eng Sci 2000, 40, 1915.

8. Adams, N.; Devasagayam, P.; Pomfret, S. J.;Abell, L.; Monkman, A. J Phys Condens Matter1998, 10, 8293; (b) Paul, R. K.; Pillai, C. K. S.Synth Met 2000, 114, 27.

9. Chan, H. S. O.; Nag, S. C.; Ho, P. K. Macromole-cules 1994, 27, 2159.

10. Desilvestro, J.; Scheifele, W. J. J Mater Chem1993, 3, 26.

11. Wei, Z.; Wan, M. Adv Mater 2002, 14, 1314.12. Kim, B. J.; Oh, S. G.; Han, M. G.; Im, S. S. Lang-

muir 2000, 16, 5841.13. Martin, C. R. Acc Chem Res 1995, 28, 61.14. Kerr, T. A.; Wu, H.; Nazar, L. F. Chem Mater

1996, 8, 2005.15. Lan, T. T.; Pinnavaia, J. Chem Mater 1994, 6,

2216.16. Boal, A. K.; Ilhan, F.; DeRouchey, J. E.; Albrecht,

T. T.; Russel, T. P.; Rotello, V. M. Nature 2000,404, 746; (b) Kumar, M. M.; Ober, C. K.; Thomas,E. L. Science 1997, 277, 1225; (c) Liu, A.; Cholli,W.; Nagarajan, A. L.; Kumar, R.; Tripathy, J. S.;Bruno, F.; Samuelson, L.; Kumar, J. J Am ChemSoc 1999, 121, 11345.

17. (a) Sudha, J. D. J Polym Sci: Polym Chem 2000,38, 2469; (b) Sudha, J. D.; Pillai, C. K. S. Polymer2005, 46, 6986.

18. Ikkala, O.; Ten, B. G. Chem Commun 2004, 19,2131.

19. (a) Grim, R. E. Clay Mineralogy. McGraw-Hill:New York 0490 HAY, HL 1966, p 384; (b) Weaver,



C. E.; Pollard, L. D. The Chemistry of Clay Min-erals; Elsevier: New York, 1973, p 15.

20. Vaia, R. A.; Krishnamurthy, R. In Polymer Nano-composite: Synthesis and Characterization andModeling; American Chemical Society: Washing-ton DC, 2001, p 1.

21. (a) Kim, B. H.; Jung, J. H.; Kim, J. W.; Choi, H.J.; Joo, J. Synth Met 2001, 117, 115; (b) Kim, B.H.; Jung, J. H.; Kim, J. W.; Choi, H. J.; Joo, J.Synth Met 2001, 121, 1311; (c) Kim, J. W.; Kim,S. G.; Choi, H. J.; John, M. S. Makromol RapidCommun 1999, 20, 450; (d) Segal, E.; Aviel, G.;Narkis, M. Prog Eng Sci 2000, 40, 1915.

22. (a) Adams, N.; Devasagayam, P.; Pomfret, S. J.;Abell, L.; Monkman, A. J Phys Condens Matter1998, 10, 8293; (b) Paul, R. K.; Pillai, C. K. S.Synth Met 2000, 114, 27.

23. Chan, H. S. O.; Nag, S. C.; Ho, P. K. Macromole-cules 1994, 27, 2159.

24. Laska, J.; Pron, A.; Lefrant, S. J Polym Sci PartA: Polym Chem 1995, 33, 1437.

25. (a) Paul, R. K.; Vijayanathan, V.; Pillai, C. K. S.Synth Met 1999, 104, 189; (b) Paul, R. K.; Pillai,C. K. S. Synth Met 2000, 114, 27.

26. (a) Cardin, D. J. Adv Mater 2002, 5, 553; (b) Thia-garajan, M.; Samuelson, L. A.; Kumar, J.; Cholli, A.L. J Am Chem Soc 2003, 125, 11502; (c) Huang, J.;Kaner, R. B. J Am Chem Soc 2004, 126, 851.

27. Sudha, J. D.; Sasikala, T. S. Polymer 2007, 48, 338.28. Lan, G. M.; Arthur, J. E. Synth Met 1995, 69, 85.29. Jia, W.; Segal, E.; Narkis, M.; Stegman, A. Polym

Adv Technol 2002, 13, 54.30. (a) Stubian, V.; Roy, R. J. Am Cer Soc 1961, 44,

625; (b) Gadsden, J. A. Infrared Spectra of Miner-als and Related Inorganic Compound, Vol. 45,Butterworth: London, 1975, p 7.

31. (a) Yue, J.; Epstein, A. J. J Am Chem Soc 1990,112, 2800; (b) Yue, J.; Wang, Z. H.; Cromack, K.R.; Epstein, A. J.; Macdiarmid, A. G. J Am ChemSoc 1991, 113, 2665; (c) Cao, Y.; Smith, P.; Heeger,A. J. Synth Met 1989, 32, 263.

32. Liu, Y. J.; Kanatzidis, M. G. Inorg Chem 1993,32, 2989.

33. (a) Cao, Y.; Li, S.; Xue, Z.; Guo, D. Synth Met1986, 16, 305; (b) Zheng, W.; Angelopolos, M.;

Epstein, A. J.; Mcdiarmid, A. G. Macromolecules1997, 30, 2953.

34. Chen, S. A.; Lee, H. T. Macromolecules 1995, 28,2858.

35. Wang, Y.; Rubner, M. F. Synth Met 1992, 47, 255.36. (a) Wu, C. G.; Yeh, Y. R.; Chen, J. Y.; Chiou, Y. H.

Polymer 2001, 42, 287; (b) Zheng, W.; Angelopolos,M.; Epstein, A. J.; Mcdiarmid, A. G. Macromole-cules 1997, 30, 2953.

37. Stutzmann, T.; Siffert, B. Clays Clay Miner 1977,25, 392.

38. Chen, S. A; Hwang, G. W. J Am Chem Soc 1995,117, 10055.

39. (a) Xia, Y.; Weisingerm, J. M.; MacDiarmid, A. G.Chem Mater 1995, 7, 443; (b) Joo, J.; Long, S. M.;Pogey, J. P.; Oh, E. J.; MacDiarmid, A. G.;Epstein, A. J Phys Rev B 1998, 57, 9567; (c)Chang, T. C.; Ho, S. Y.; Chao, K. J. J Chin ChemSoc 1992, 39, 209.

40. Taka, T.; Laakso, J.; Levon, K. Solid State Com-mun 1994, 92, 393.

41. Rukolainen, R.; Makinen, T.; Torkkeli, T.; Makela,R.; Serimaa, G.; Ten, B. G. Ikkala, O. Science1998, 280, 557.

42. (a) Wu, C. G.; Yeh, Y. R.; Chen, J. Y.; Chiou, Y. H.Polymer 2001, 42, 287. (b) Zheng, W.; Angelopo-los, M.; Epstein, A. J.; Mcdiarmid, A. G. Macro-molecules 1997, 30, 2953.

43. Chen, S. A.; Hwang, G. W. J Am Chem Soc 1995,117, 10055.

44. Lee, D.; Char, K.; Lee, S. W.; Park, Y.W. J MaterChem 2003, 13, 2942.

45. Brindley, G. W.; Moll, W. F. Am Mineralogist1965, 50, 1355.

46. Wei, Z. X.; Zhang, Z. M.; Wan, M. X. Langmuir2002, 18, 917.

47. Langer, J. J Adv Mater Opt Electron 1999, 9, 1.48. Hous, G. In Anionic Surfactant Organic Chemis-

try, Stache, H. W., Ed.; Marcel Dekker: New York,1995, p 82.

49. Ikkala, O.; Ten Brinke, G. Science 2002, 295, 2407.50. Vaia, R. A.; Teukolsky, R. K.; Giannelis, E. P.

Chem Mater 1994, 8, 1017.51. Mehrotra, G.E.P. Solid State Commun 1991, 77,

155.



Facile Green Strategy for Micro/Nano Structured Conducting Polyaniline-Clay Nanocomposite via...

Documents

Transcript of Facile Green Strategy for Micro/Nano Structured Conducting Polyaniline-Clay Nanocomposite via...