bhadra et al

8/6/2019 Bhadra et al

http://slidepdf.com/reader/full/bhadra-et-al 1/11

Journal of Chemical Engineering and Materials Science Vol. 2(1), pp. 1-11, January 2011Available online at http://www.academicjournals.org/jcemsISSN-2141-6605 ©2011 Academic Journals

Full Length Research Paper

Polyaniline based anticorrosive and anti-moldingcoatingSambhu Bhadra, Nikhil K. Singha and Dipak Khastgir *

Rubber Technology Centre, Indian Institute of Technology, Kharagpur, India, 721302.

Accepted 11 March, 2010

Polyaniline (PAni) was synthesized by miniemulsion polymerization. One coating solution of poly(epichlorohydrine-co-ethylene oxide) (ECO) and another of ECO and PAni mixture were prepared in amixture of solvents and then applied on cast iron and stainless steel coupons using spin coatingtechnique. The efficiency of these coatings to retard the environmental rust formation was studied asper the ASTM D610-01 and the rate of corrosion was determined electrochemically using a potentiostat/galvanostat. The efficiency of these two coatings to resist the mold/ fungal growth was estimated as perthe ASTM D5590-00. The results revealed that the PAni can retard the corrosion to a great extent byaccelerating the formation of a passive Fe 2O3 layer on the cast iron and stainless steel surfaces. PAnialso has the ability to impede the mold growth by escalating the release of chlorine dioxide (ClO 2).

Key words: Corrosion, polyaniline, iron, stainless steel, SEM.

INTRODUCTION

The intrinsically conducting polymers (ICP) haveimportant potential as a protecting material against

corrosion on metal surfaces (Beck et al., 1994; Ahmedand MacDiarmid, 1996; Sitaram et al., 1997; Camalet etal., 1998; Martins et al., 2002; Tallman et al., 2002; Irohet al., 2003; Tan and Blackwood, 2003; Zarras et al.,2003). Among the available ICPs, polyaniline (PAni) isthe most promising polymer because of its ease ofsynthesis, tunable properties, low cost monomer andgood thermal stability (Genies et al., 1990, Gospodinovaand Terlemezyan, 1998; Bhadra et al., 2009). Threelayers of coating are required with traditional materials toobtain an adequate protection of metal surfaces againstcorrosion. Whereas, a single coat of ICP can provide thesame degree of protection, leading to the substantial

savings of material as well as cost of application(Wessling, 1998).The majority of the literature focusing on the use of

conducting polymers as anticorrosive coating mainly

*Corresponding author. E-mail: [email protected]. Tel:91-3222-283192. Fax: 91-3222-282292

Abbreviations: PAni, Polyaniline; ECO, epichlorohydrine-co-ethylene oxide; ICP ,Intrinsically conducting polymers.

deals with the electrodeposition of ICP on metal surfaces(Lu et al., 1995, Camalet et al., 1999, Ozyilmaz et al.,

2005a, Ozyilmaz et al., 2005b, Grgur et al., 2006).However, this technique is time consuming and notsuitable for mass application involving different shapeand size of metal surfaces. Therefore, organic coatingcontaining ICP may be a better choice for massapplication. In this study, a coating containing PAniparticles as ICP and poly (epichlorohydrine-co-ethyleneoxide) (ECO) as the base polymer was applied on themetals and paper coupons and the efficiency of thecoating to retard the corrosion and mold/fungal growthwas investigated. The PAni was chosen as a corrosionprotecting ICP because of its out standing properties asmentioned earlier. The ECO was selected as a base

matrix because of its high polarity and therefore expectedto have good compatibility with the PAni. Moreover, theECO is saturated in nature, therefore inherently moreresistance to atmospheric oxidation. In general, corrosionstudy is carried out electrochemically using potentiostat/ galvanostat and the rate of corrosion is obtained inmillimeter per year (Yeh et al., 2001; Yeh et al., 2004).

However, the validity of such test to assess thepractical situation may not be always realistic. Therefore,environmental corrosion test is essential to understandthe potential of ICP as an anticorrosive material for metalsurfaces. However, the available literature on the



2 J. Chem. Eng. Mater. Sci.

Figure 1. Different structures of polyaniline (PAni).

Figure 2. Effect of weight percentage of the PAni content on the DCconductivity of ECO-PAni mixture .

environmental corrosion study of the PAni coating onmetal surfaces is relatively less. In this study,environmental corrosion test was performed as per theASTM D610-01. The rate of electrochemical corrosionwas also estimated from the potentiostat/ galvanostatstudy. The organic coating containing an ICP may alsoprovide a protection against the fungal growth.

The fungicidal/ mold protection efficiency of ECO-PAnicoating was also evaluated following the ASTM D5590-00. Sufficient corrosion studies have been carried out onICP coated mild steel (Lu et al., 1995; Camalet et al.,1996; Camalet et al., 1998; Ozyilmaz et al., 2005a; Grguret al., 2006). However, corrosion studies on ICP coatedcast iron and stainless steel (SS) are relatively less

(Camalet et al., 1998; Spinks et al., 2002). Therefore, twodifferent substrates were selected for the present study,namely cast iron and stainless steel in order toinvestigate the effectiveness of PAni to retard thecorrosion on those surfaces under experimentalconditions.

EXPERIMENTALS

Materials

Poly (epichlorohydrine-co-ethylene oxide) (ECO), Tg = - 30°C,ML1+4 at 100°C = 90 - 102) was obtained from Aldrich. Agar powderwas purchased from HiMedia laboratories Pvt. Ltd., Mumbai, India.



Aniline, 1-methyl 2-pyrrolidinone (NMP), ethyl methyl ketone (MEK),ammonium peroxydisulphate (APS) and stannous chloride wereprocured from Merck Ltd., Mumbai, India. Hydrochloric acid (HCl)was acquired from Ranbaxy. Sodium dodecyl sulphate (SDS) andcetyl alcohol were obtained from Loba Chemie, Mumbai, India.Methanol was supplied by SISCO Research Laboratories Pvt. Ltd.,Mumbai, India. Stainless steel: EN-standard Steel no. k.h.s DIN1.4401, EN standard Steel name X5CrNiMo17-12-2, SAE grade316, UNS S31600 was procured from Piyush Steel (India) Pvt. Ltd.Cast iron: BS - 497-76, Fe 94.3 C 3.4, Si 1.8, Mn 0.5 was obtainedfrom Unicast, India.

Synthesis of polyaniline (PAni)

0.01 mol SDS (2.9 g), 0.04 mol (9.7 g) cetyl alcohol and 100 mldeionized (DI) water were placed in a beaker, stirred for one hourwith a high-speed mechanical stirrer to form miniemulsion. To thisminiemulsion, 0.1 mol (9.3 g) aniline and 10 ml HCl were added,stirred and then the polymerization reaction was started through thedrop-wise addition of APS solution (0.1 mol (22.8 g) APS in 100 mlDI water). The polymerization reaction was carried out for 6 h at 0 -5°C with constant stirring. After 6 h of polymerization, the reaction

was stopped through the addition of 50 ml of methanol. Thereaction mixture was then stirred with a mild reducing agent (0.01mol (2.2 g) of SnCl 2 and 10 ml HCl) for 1 h. A deep green PAni wasprecipitated, which was filtered, washed with DI water and finallydried in a vacuum oven at room temperature (Bhadra et al., 2006).The DC conductivity of the resultant PAni was 0.015 S cm -1.

Depending on the oxidation state and protonation level, the PAnican either be highly conducting or insulating in nature. Differentstructures of PAni are presented in Figure 1. The doped halfoxidized and half reduced emeraldine base (EB) form issignificantly conducting, whereas fully reduced leucoemeraldinebase (LEB) and fully oxidized pernigraniline base (PNB) are mainlyinsulating in nature (Bhadra et al., 2006). The synthesized PAni isconducting in nature, which suggests that it contains highconcentration of EB form.

Preparation of coating solutions

5 wt.% of ECO was dissolved in 4:1 MEK and NMP solvent mixture.Different weight percentage of PAni with respect to the ECO wasadded to ECO solutions and the mixtures were agitated for 6 h witha mechanical stirrer. The solid content of each mixture wasmeasured and excess solvent was added wherever needed tomaintain a 5 wt.% total solid content in each of these mixtures.Increasing the PAni concentration in the mixture, the conductivitywas increased at a faster rate up to the 10 wt.% of PAni (Figure 2).With further increase in the loading of PAni, the rate of increase ofconductivity was relatively slow and few PAni particles started tosettle down. Therefore, for all experiment, a mixture containing 10wt.% of PAni with respect to the ECO and 5 wt.% total solid content

was maintained. The mixture containing 5 wt.% total solid contentwith 10 wt.% of PAni with respect to the ECO was designated“ECO-PAni”. A coating solution of ECO in a mixture of samesolvents was also prepared for the comparison.

Characterization

DC conductivity

The DC conductivity of the PAni powder was measured using milli-ohm meter, GOM 802, GW Instek, Taiwan. Sample pellet from PAnipowder was prepared with the help of Perkin Elmer hydraulic press.

The DC conductivity of ECO solution and ECO-PAni mixture was

Bhadra et al. 3

measured using a systronics conductivity meter 304 (Ahmedabad,India).

Environmental corrosion/ rust testing under high humid conditions

Cast iron and stainless steel coupons (2 x 3 cm 2) were cleaned withHCl followed by acetone, and then dried in a vacuum oven at 100°Cfor 4 h. These coupons were then spin coated (SCU-2005, ApexInstrument Co., Kolkata, India) with the ECO solution and ECO-PAni mixture. Double coat was applied with a speed of 2000 rpm,for 40 s at room temperature, and then dried for 4 h in a vacuumoven at 100°C. The thickness of the coating was estimated from thescanning electron microscopic (SEM) (JSM 5800, JEOL, JAPAN)image. The coated coupons were gold coated and top view SEMimages were captured in order to estimate the coating thickness(Figure 3). The thickness of the coating in all samples was ~35 µm.For the environmental corrosion test, the coated coupons weremounted on a perforated platform (with water underneath toincrease the humidity) inside a desiccator. The lid of the desiccatorwas kept partially opened for the passage of air and light. Thehumidity inside the desiccator was detected in the level RH ~90%.A photograph using a digital camera was taken at the start of theexperiment (0 days) and another photograph was taken after 14days of exposure to high humid atmosphere. The degree ofcorrosion/ rust generated on the metal surfaces was rated as perthe ASTM D610-0.

Determination of corrosion rate by electrochemical method

The ECO solution and ECO-PAni mixture were spin coated onmetal coupons (1 x 1 cm 2) with coating thickness ~35 µm. Theapplication of coat and measurement of coating thickness wereaccomplished according to the procedure discussed earlier. TheECO and ECO-PAni coated coupons were then used as the

working electrode in the electrochemical cell in such a fashion sothat the coated side of the coupon came in direct contact with theelectrolyte (5% NaCl solution). The edges of the coupons weresealed with quick setting epoxy cement. All electrochemicalmeasurements such as corrosion potential, polarization resistanceand corrosion current were measured using a Meinsbergerpotentiostat/ galvanostat, model: PS6, Germany, in a standardcorrosion cell equipped with a platinum counter-electrode and asaturated calomel electrode (SCE) as a reference electrode.

The open circuit potential (OCP) at the equilibrium state of thesystem was recorded as the corrosion potential ( E corr in volts vs.SCE). The potentiodynamic scanning was carried out by sweepingthe applied potential from 300 mV below to 300 mV above the E cor

value at the scan rate of 2 mV sec -1 and the corresponding currentchange was recorded. The polarization resistance ( R p in .m 2

value was obtained from the slope of the potential vs. current plot.The corrosion current ( I corr ) was determined by superimposing astraight line along the linear portion of the cathodic or anodic curveand extrapolating it through the E corr . The corrosion rate ( R corr), inmillimeter per year, (mm y –1 ) was calculated using the Equation 1(Yeh et al., 2001, 2004):

.).(0254.013×

××=

d A

W E I R corr

corr

(1)

where, E.W. is the equivalent weight, I corr in mA m –2 , A is the area inm2 and d is the density in g m –3 .




Figure 3. SEM images, top view was taken to obtain the coating thickness (a) is

ECO coating and (b) is ECO-PAni coating, both have thickness ~35 µm .

Fungal/ mold growth testing

Both the ECO and ECO-PAni were coated on 2 x 3 cm 2 hard papercoupons. Agar powder was spread on a petri dish to prepare a bed,water was sprayed on the agar bed and then the coated couponswere placed on the wetted agar bed. The whole assembly was keptunder high humid conditions as discussed earlier and water wasspread everyday. All these arrangement was made to createsuitable environment for the mold growth. One photograph wastaken at the beginning of the experiment (0 days) and the secondphotograph was taken after four weeks. The mold growth was rated

as per the ASTM D5590-00.

RESULTS AND DISCUSSION

Environmental rust protection by the ECO and ECO-PAni coatings

On exposure to a humid atmosphere, metal surfaces arecorroded at different rates depending on the type ofcoating present on their surfaces. Figures 4 and 5 showthe photographs of the ECO and ECO-PAni coated cast

iron coupons, respectively, after exposure to humidconditions for 14 days. There was a generation of generalrust on the ECO coated iron coupons after exposure tohumid atmosphere for 14 days. The degree of rustformation was 15 - 30% on the iron coupons coated withthe ECO. Whereas, there was only pinpoint rustformation on the iron coupons coated with the ECO-PAniand the area of rust formation was less than 1% of thetotal coated surface. As per the ASTM D610-01, the rust

formation is graded from 0 to 10 depending on the area(%) of rust formation with in the specified period. As perthe ASTM grading, the level of rust grade for the ECOcoated coupons is 2, whereas the same for the ECO-PAni coated coupons is 6. The lower the grade, thepoorer the protection against rust formation.

These results revealed that the ECO-PAni coating hassuperior rust protection ability on iron surface comparedto that of the ECO coating. The environmental corrosiontest was also carried out on the stainless steel substratecoated with ECO and ECO-PAni, but significant amountof rust was not developed with the specified period of



Bhadra et al. 5

Figure 4. Photographs of the ECO coated iron couponsafter exposure to the high humid atmosphere for 14 days.Images a, b, c, d are obtained from different spots .

Figure 5. Photographs of the ECO-PAni coated ironcoupons after exposure to the high humid atmosphere for14 days. Images a, b, c, d are obtained from differentspots .




Figure 6. Mechanism for the corrosion protection of PAni on iron surfacevia the formation of passive oxide layer.

testing. The mechanism for the protection against rustformation by PAni is discussed in the following section.

33

03 +→+

++ FePAniFePAni mmm

(2)

4424 220

+→++−+ mOH PAniOmH mOPAni m

(3)

362 2323

+→+−+

O H OFeOH Fe (4)

PAni m+ oxidizes Fe/Fe 2+ to Fe 3+ and itself is reduced toPAni 0 (Equation 2 and Figure 6a). The PAni again getsoxidized to PAni m+ (Equation 3) after the reaction withdissolved oxygen. Fe reacts with the OH – ion (Equation4 and Figure 6b) to form a hard insoluble Fe O passivelayer. The generation of the passive Fe 2O3 oxide layer isaccelerated due to the redox catalytic effect of PAni. Thispassive layer prevents the oxidation of inner metalsurfaces and thus protects/ retards the corrosion of the

iron. This process occurs in cyclic order till the PAni layerremains active (Rout et al., 2003; Nguyen et al., 2004).

The SEM images of the corroded surfaces of thecoated iron coupons were captured after exposure tohigh humid conditions for 14 days in order to identify theformation of oxide layers (Figure 7). A fine compact oxidelayer was observed on the ECO-PAni coated iron surface(Figure 7a), whereas few discrete bigger spots for oxideformation were observed on the ECO coated iron surface(Figure 7b). These discrete spots on the ECO coatedsurface allow the diffusion of oxygen and moisture tocause further corrosion, whereas relatively densed oxidelayer on the ECO-PAni coated surface prevent thediffusion process leading to the better protection againstenvironmental corrosion (Rout et al., 2003).

Electrochemical corrosion rate on ECO and ECO-PAni coated metal surfaces

The Tafel plots for the ECO and ECO-PAni coated steelcoupons are shown in Figures 8a and 8b respectively.Corrosion protection by the ECO and ECO-PAni coatingcould be judged from the values of the corrosion potential



Bhadra et al. 7

Figure 7. SEM images of the (a) ECO-PAni coated iron couponand (b) ECO coated iron coupon after exposure to the high humidatmosphere for 14 days.

Figure 8. The Tafel plots for the ECO (a) and ECO-PAni (b) coated steelcoupons .




Table 1. Corrosion potential ( E corr), polarization resistance ( R p), corrosion current(I corr ), and corrosion rate ( R corr ) of ECO and ECO PAni.

Sample E corr (mV) I corr (mA m –2 ) R p ( .m 2) R corr (mm y –1 )ECO -320 30 0.29 1.5ECO-PAni +170 9 1.08 0.4

(E corr), polarization resistance ( R p ), corrosion current(I corr ), and corrosion rate ( R corr ), as listed in Table 1. TheE corr , I corr and R p values for the ECO-PAni coating aremuch higher compared to those of the ECO coating.Substantially higher values of these parameters signifythat the ECO-PAni is superior to the ECO as a corrosionprotecting coating. In fact, the calculated rate of corrosionfor the ECO coated surface is 3.5 times faster than that ofthe ECO-PAni coated surface. The electrochemicalcorrosion test on cast iron failed to produce reproducibleresults because of uneven surface. Therefore, theseresults were not reported.

Mold/fungal resistance efficiency of ECO and ECO-PAni coatings

Mold is a type of fungus, black or green in color, whichgrows under damp and moist environment in absence ofsufficient sunlight and air flow. Mold generation isobserved on left over food, on walls of toilet andbathroom etc. Mold growth requires the presence of moldspores (bacteria), sufficient moisture, and food forbacteria. To control the mold growth, the level of moisturehas to be controlled, which is a challenging task. It is verydifficult to control the mold growth on surfaces byapplying only paints, because paints act as food supplierfor the bacteria, which are responsible for the moldgeneration and accelerate the mold growth. Theeffectiveness of PAni to control the mold growth was alsoinvestigated in this study.

Figure 9a shows the images of four coated coupons atthe start of the experiment. Top two coupons were coatedwith the ECO and the bottom two coupons were coatedwith the ECO-PAni. Figure 9b shows the mold growth onthese coated coupons after specified period of time andconditions as discussed earlier. Through visual

inspection, the generation of mold on each coatedcoupon was observed after four weeks. However, theextent of mold growth was much higher on the ECOcoated coupons compared to that of the ECO-PAnicoated coupons. The ECO coated coupons showed >10% mold growth after 4 weeks, whereas the ECO-PAnicoated coupons showed trace of mold growth after thesame time of exposure. The mold growth was rated asper the ASTM D5590-00. The mold growth rate on theECO and ECO-PAni coated coupons are 2 and 1,respectively. This observation suggests that the PAni hasability to retard the mold/fungal growth.

The probable mechanism for the mold protection by theHCl doped PAni is illustrated in Figure 10. In the dopedPAni, HCl is present both as a dopant as well as anabsorbed material. During reaction (a) HCl may lead tothe formation of a hypochlorus acid (HOCl) by oxidation(Folkes et al., 1995) and (b) The doped PAni is convertedto an undoped amine. The HOCl thus formed may giverise to a chlorine dioxide (ClO 2) through different internalreactions (step c) (Adam et al., 1992; Wentworth et al.,1965). (c) The ClO 2 formed is reduced by extractingelectrons from the amine, forming an aminium cation andthe chlorite anion. (d) The aminium cation is converted toan iminium cation after loosing of a proton from anadjacent carbon atom and oxidizes another ClO 2molecule. This iminium chlorite is unstable to differentnucleophilic attack and it releases ClO 2 slowly for alonger period of time in presence of moisture. This ClO 2 isa superior oxidizing agent and it can protect, retard or killthe growth of bacteria, molds, fungi, algae, protozoa andvirus (Wellinghoff and Kampa, 1999). This process maytake place in cyclic order with the continuous generationof iminium chlorite till the PAni is active.Dehydrohalogenation is often encountered in chlorinecontaining polymers like ECO. As a result the ECO mayrelease some HCl. However, only the ECO coating is noteffective to reduce the mold growth.

Conclusion

Polyaniline (PAni) was synthesized by miniemulsionpolymerization. Cast iron and stainless steel couponswere coated with the poly (epichlorohydrine-co-ethyleneoxide) (ECO) solution and ECO-PAni mixture byspin coating with coating thickness ~35 µm. The rustgrowth study on the cast iron (as per the ASTM D610-01)revealed that the protection against rust generation on

the ECO-PAni coated iron surfaces was much better thanthat of the ECO coated iron surfaces. Theelectrochemical corrosion study revealed that the rate ofcorrosion on the ECO coated stainless steel surfaceswas almost 3.5 times faster than that of the ECO-PAnicoated surfaces. Both the results confirmed that the PAnidispersed in the ECO served as a good anticorrosiveagent for metal surfaces like cast iron and stainless steel.The efficiency of these two coatings to retard the mold/ fungal growth was estimated as per the ASTM D5590-00.The results suggested that the ECO-PAni coating hasability to retard the mold growth. The mechanism for the



Bhadra et al. 9

Figure 9. Mold / fungal growth test: (a) top Petri dish contains freshly ECO (upper cards) and ECO-PAni(lower cards) coated cards, (b) bottom Petri dish contains same samples in same position but thisphotograph was taken after 4 week exposure to a suitable environment for mold / fungal growth




Figure 10. Schematic for the formation of chlorine dioxide (c) from the HCl doped PAni(a), conversion of an amine precursor (b) to an iminium chlorite (d) and release ofchlorine dioxide (ClO 2) gas from iminium chlorite due to nucleophilic attack .

protection of corrosion and mold by the PAni has beendiscussed elaborately. PAni protects the corrosion byaccelerating the formation of a passive Fe 2O3 layer oniron surfaces and retards the mold growth by escalatingthe release of chlorine dioxide (ClO 2).

REFERENCES

Adam LC, FhbiBn I, Suzuki K, Gordon G (1992). Hypochlorous aciddecomposition in the pH 5-8 region. Inorg. Chem., 31: 3534-3541.

Ahmed N, MacDiarmid AG (1996). Inhibition of corrosion of steels withthe exploitation of conducting polymers. Synth. Met. 78: 103-110.

Beck F, Michaelis R, Schloten F, Zinger B (1994). Filmformingelectropolymerization of pyrrole on iron in aqueous oxalic-acid.Electrochim. Acta, 39: 229-234.

Bhadra S, Singha NK, Khastgir D (2006). Polyaniline by newminiemulsion polymerization and the effect of reducing agent onconductivity. Synth. Met., 156: 1148-1154.

Bhadra S, Singha NK, Lee JH, Khastgir D (2009). Progress inpreparation, processing and applications of polyaniline. Prog. Polym.Sci., 34: 783–810.

Camalet JL, Lacroix JC, Aeiyach S, Ching KC, Lacaze PC (1996).Electrodeposition of protective polyaniline films on mild steel. J.Electroanal. Chem., 416: 179-182.

Camalet JL, Lacroix JC, Aeiyach S, Ching KC, Lacaze PC (1998).Electrosynthesis of adherent polyaniline films on iron and mild steel inaqueous oxalic acid medium. Synth. Met., 93: 133-142.

Camalet JL, Lacroix JC, Aeiyach S, Ching KC, Lacaze PC (1999).Electrodeposition of polyaniline on mild steel in a two step process.Synth. Met., 102: 1386-1387.

Folkes LK, Candeias LP, Wardman P (1995). Kinetics and mechanismsof hypochlorous acid reactions. Arch. Biochem. Biophys., 323: 120-126.

Genies EM, Boyle A, Lapkowski M, Tsintavis C (1990). Polyaniline: Ahistorical survey. Synth. Met., 36: 139-182.

Gospodinova N, Terlemezyan L (1998). Conducting polymers preparedby oxidative polymerization: Polyaniline. Prog. Polym. Sci., 23: 1443-1484.

Iroh JO, Zhu Y, Shah K, Levine K, Rajagopalan R, Uyar T, Donley M,Mantz R, Johnson J, Voevolin NN, Balbyshev VN, Khramov AN(2003). Electrochemical synthesis: A novel technique for processingmulti-functional coatings. Prog. Org. Coat., 47: 365-375.

Lu WK, Elsenbaumer RL, Wessling B (1995). Corrosion protection ofmild steel by coatings containing polyaniline. Synth. Met., 71: 2163-2166.

Martins JI, Bazzaoui M, Reis TC, Bazzaoui EA, Martins L (2002).Electrosynthesis of homogeneous and adherent polypyrrole coatingson iron and steel electrodes by using a new electrochemicalprocedure. Synth. Met., 129: 221-228.

Nguyen TD, Nguyen TA, Pham MC, Piro B, Normand B, Takenouti H(2004). Mechanism for protection of iron corrosion by an intrinsicallyelectronic conducting polymer. J. Electroanal. Chem., 572: 225-234.

Ozyilmaz AT, Kardas G, Erbil M, Yazici B (2005a). The corrosionperformance of polyaniline on nickel plated mild steel. Appl. Surf.Sci., 242: 97-106.

Ozyilmaz AT, Tuken T, Yazici B, Erbil M (2005b). The electrochemical



synthesis and corrosion performance of polyaniline on copper. ProgOrg. Coat., 52: 92-97.

Rout TK, Jha G, Singh AK, Bandyopadhyay N, Mohanty ON (2003).Development of conducting polyaniline coating: A novel approach tosuperior corrosion resistance. Surf. Coat. Technol., 167: 16-24.

Sitaram SP, Stoffer JO, OKeefe TJ (1997). Application of conductingpolymers in corrosion protection. J. Coat. Technol., 69: 65-69.

Spinks GM, Dominis AJ, Wallace GG, Tallman DE (2002). Electroactiveconducting polymers for corrosion control. J. Solid State.Electrochem., 6: 85-100.

Tallman DE, Spinks G, Dominis A, Wallace GG (2002). Electroactiveconducting polymers for corrosion control. J. Solid State.Electrochem., 6: 73-84.

Tan CK, Blackwood DJ (2003). Corrosion protection by multilayeredconducting polymer coatings. Corr. Sci., 45: 545-557.

Wellinghoff ST, Kampa JJ (1999). Amine-containing biocidalcompositions containing a stabilized chlorite source. US Patent, pp.5, 914,120.

Bhadra et al. 11

Wentworth JF, Hefler JR (1965). Process for the treatment of water.Oaklawn, US Patent, 3,082,146.

Wessling B (1998). Dispersion as the link between basic research andcommercial applications of conductive polymers (polyaniline). Synth.Met., 93: 143-154.

Yeh JM, Liou SJ, Lai CY, Wu PC (2001). Enhancement of corrosionprotection effect in polyaniline via the formation of plyaniline-claynanocomposite. Chem. Mater., 13: 1131-1136.

Yeh JM, Liou SJ, Lin CG, Chang YP, Yu YH, Cheng CF (2004).Effective enhancement of anticorrosive properties of polystyrene bypolystyrene-clay nanocomposite materials. J. Appl. Polym. Sci., 92:1970-1976.

Zarras P, Anderson N, Webber C, Irvin DJ, Irvin JA, Guenthner A,Stenger-Smith JD (2003). Progress in using conductive polymers ascorrosion-inhibiting coatings. Rad. Phys. Chem., 68: 387-394.

bhadra et al

Documents