Synthetic Metals 156 (2006) 379–386

Vapour phase polymerisation of pyrrole on cellulose-basedtextile substrates

L. Dall’Acqua a, C. Tonin a,∗, A. Varesano a, M. Canetti b, W. Porzio b, M. Catellani b

a CNR-ISMAC, Institute for Macromolecular Studies, C.so G. Pella, 16 Biella, Italyb CNR-ISMAC, Institute for Macromolecular Studies, Via E. Bassini, 15 Milano, Italy

Accepted 27 December 2005Available online 10 March 2006

Abstract

Conducting textiles were prepared embedding polypyrrole in natural and man made cellulose-based fibres, such as cotton, viscose, cupro andlyocell, by means of in situ polymerisation. Chemical vapour phase deposition of polypyrrole is a suitable process for producing electro-conductivecomposites in two steps: (a) fabric impregnation with an aqueous solution of oxidant and dopant and subsequent drying; (b) exposition to pyrrolevapour and polymerisation.

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Comparative morphological and structural analysis was carried out on the conducting viscose prepared with both vapour and liquid phasesrocesses and some significant differences in the structural, calorimetric and electrical properties were highlighted, due to the different methodsf preparation. Vapour phase prepared fabrics show a high uniform polypyrrole coating on the fibre surface and its partial penetration inside themorphous zones of the fibre bulk.

WAXD analysis shows that the conducting fabrics preserve the crystalline structure of the cellulose matrix, while SAXS results evidence theresence of a nanoparticle dispersion of polypyrrole in the cellulose matrix. Polypyrrole–cellulose conducting composite textiles show gooderformances to light exposure and washing fastness tests.

2006 Elsevier B.V. All rights reserved.

eywords: Polypyrrole; Vapour phase deposition; Conductive polymer; Cellulose; Textile

. Introduction

Conductive polymers have attracted the attention of a greatumber of researchers in the textile field due to their potentialpplications in composites with natural, artificial or syntheticbres [1–9]. The affinity to several kinds of fibres, yarns and fab-ics with doped conjugated polymers, permits the production ofomposite textiles with improved electrical properties. Fabricsoated with or containing conductive polymers are suitable forechnological applications such as electromagnetic interferenceEMI) shielding [4–6], heat generation [7], cooling system [8]nd electro-static discharge (ESD) [9].

Polypyrrole (Ppyr) is one of the most suitable conductiveolymers for deposition on textile materials due to its excellentonductivity and relevant environmental stability [10,11]. Ppyr

∗ Corresponding author.E-mail address: c.tonin@bi.ismac.cnr.it (C. Tonin).

is commonly produced by electrochemical synthesis or chemicaloxidative polymerisation in aqueous solution and shows goodaffinity with natural and artificial fibres. Textile substrates canbe easily covered with a Ppyr layer by immersion of the fabric inthe polymerisation solution containing pyrrole (Pyr), an oxidantand a doping agent.

Recent research carried out in our laboratories, shows thatpolypyrrole can be embedded in natural and man made cellulose-based fibres, such as cotton, viscose, cupro and lyocell, by meansof internal polymerisation taking place in the amorphous regionof the fibres [12]. Pyrrole was applied by a simple finishingprocess at room temperature from an aqueous solution of themonomer that penetrates into the cellulose substrate similarly toa non-reactive dye. Subsequent polymerisation caused its per-manent insolubility in the internal fibre structure, leading to highlevels of fastness to washing and to light exposure, without sig-nificant modification of the mechanical properties of the fibres.

In this work an alternative process, consisting of polymeri-sation of the pyrrole monomer in vapour phase on a viscose

379-6779/$ – see front matter © 2006 Elsevier B.V. All rights reserved.

oi:10.1016/j.synthmet.2005.12.021

380 L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386

fabric has been studied. The fabric was previously impregnatedwith an oxidant and a doping agent in aqueous solution and thenexposed to pyrrole vapour at 60 ◦C. The process is inexpensive,solvent-free and allows the recovery of both the dopant and oxi-dant solutions along with the unreacted monomer.

In the conducting textiles prepared with this method, thepolypyrrole amount was estimated by means of the weight incre-ment and related to the spectroscopic and calorimetric data.The fibre morphology, thermal stability and chemical interactionbetween Ppyr and cellulose, for different loadings, were investi-gated. The mechanical properties of the textiles are affected bythe polymerisation process but the washing and light fastness arevery good. The conductivity of the samples depends on the poly-mer amount, and both the electrical and thermal properties arestrongly influenced by the temperature and atmosphere ageing.To prevent oxidation by air silicon-based coatings were appliedafter polymerisation.

2. Experimental

2.1. Materials and methods

Viscose standard fabric with 146 g m−2 weight, 0.6 mmthickness and 13.22 �m average fibres diameter, was pur-chased from EMPA Testmaterialen (CH). Pyrrole monomer(Pyr, >97%) and dopant (antraquinone-2,6-disulfonic acid dis-o(r1

miatPsfFt3wdo

tai31rt

iutr

2.2. Analysis and characterisation

Microscopic investigations were performed by a LeicaDMLP Light Microscope and a 435 VP LEO (Leica ElectronOptics) scanning electron microscope (SEM), using an acceler-ation voltage of 15 kV and 20 mm working distance. The fibreswere mounted on aluminium specimen stubs with double-sidedadhesive tape and sputter coated with a 20 nm thick gold layerin rarefied argon, using an Emitech K 550 Sputter Coater, witha current of 20 mA for 180 s.

FT-IR spectra were obtained by using a Thermo NicoletNexus with attenuated total reflection technique (ATR SmartEndurance). Spectra were recorded in the range from 4000 to550 cm−1, with 100 scansions and a resolution of 4 cm−1.

Differential scanning calorimetry (DSC) was performed witha Mettler Toledo DSC 821, calibrated by indium standard. Thecalorimeter cell was flushed by 100 ml min−1 of nitrogen. About3 mg of fibres were used in each test using an aluminium cru-cible. The temperature program was set in the range from 25 to500 ◦C, at a heating rate of 10 ◦C/min collecting the data by theMettler Toledo Star System.

Wide-angle X-ray diffraction (WAXD) measurements wereobtained at room temperature using a Siemens diffractometermodel D-500 equipped with a Siemens FK 60–10, 2000 W Cutube (Cu K� radiation, λ = 0.154 nm). The operating voltageand current were 40 kV and 40 mA, respectively. The data werec

cmsFT2wdpnac[h

d6fsDPwibRapis

dium salt, >97%) were purchased from Fluka, the catalystferric chloride hexahydrate, 98%) from Aldrich. The weightatio between dopant and oxidant used for polymerisation was:5.39 (w/w).

The conducting fabrics obtained from vapour phase poly-erisation were prepared as follows. Fabric samples were

mpregnated with both oxidant and dopant in aqueous solution,gitated (130 rpm) for 1 h, dried for 24 h at room tempera-ure then suspended in a closed vessel thermostated at 60 ◦C.yrrole was added in the bottom vessel, and the polymeri-ation lasted for 8 h. The excess polymer was then removedrom the fibre surface by washing in an Electrolux WascatorOM 71MP laboratory washing machine at standard condi-

ions (program 8A: 30 ◦C, 1 g l−1 of ECE phosphate detergent,0 min, according to ISO 26330:1994). The polymerised textilesere coated, before the electrical measurements, with poly-imethylsiloxane oil to protect the fabrics from atmosphericxidation.

The conducting fabrics obtained by polymerisation in solu-ion were prepared using weight ratios among monomer, catalystnd dopant of 1:9:1.67 (w/w). The fabric samples were soakedn aqueous solution containing both catalyst and dopant, for0 min, then pyrrole was added and the polymerisation ran for5 h at room temperature [12]. The excess polymer was thenemoved from the fibres surface by the above-described labora-ory washing machine.

The samples were labelled VPV(x) (viscose/polypyrrolen vapour phase) and VPL(x) (viscose/polypyrrole in liq-id phase), were x indicates the FeCl3 amount in g l−1 inhe impregnation solution and in the polymerisation solution,espectively.

ollected from 5 to 35 2θ◦ at 0.02 2θ◦ intervals.Small-angle X-ray scattering (SAXS) measurements were

onducted at 22 ◦C with a Kratky Compact Camera. Monocro-atized Cu K� radiation (λ = 0.154 nm) was supplied by a

tabilized Siemens Krystalloflex 710 generator and a SiemensK 60–04, 1500 W Cu target tube operated at 40 kV and 25 mA.he scattered intensity was counted at 197 angles in the rangeθ = 0.15–3.0◦, by using a step scanning proportional counterith pulse height discrimination. The measurements were con-ucted orienting the fibre axis of the sample in the directionerpendicular and parallel to the axis of the primary beam, alter-atively. The blank was subtracted from the sample scatteringfter correction for the sample absorption. A de-smearing pro-edure was applied to correct instrumental-broadening effects13]. For all SAXS measurements the abscissa variable was= 4π sin θ/λ.

The textile and electrical properties were evaluated after con-itioning the samples for 24 h in standard atmosphere (20 ◦C,5% R.H.). The measurement of the fibre fineness was per-ormed by means of a Reynold & Branson projection micro-cope. Tensile properties were measured by an Instron 5500Rynamometer at constant rate elongation (CRE) interfaced toC software Instron Merlin Version 8.12.00. Washing fastnessas determined by means of an Original Hanau Linitest accord-

ng to UNI EN ISO 105-C06 A1S. Light fastness was measuredy an Atlas Xenotest Alpha, according to UNI EN ISO 105-B02.ubbing fastness, dry and moist, were obtained by a SDL device,ccording to UNI EN ISO 105-X12. The washing cycles wereerformed in an Electrolux Wascator FOM 71MP-Lab wash-ng machine at fixed temperature and standard conditions. Allamples were tumble-dried after washing. Electrical properties

L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386 381

Fig. 1. SEM picture of (a) pristine viscose, magnification 3000×, and SEM pictures of VPV samples prepared with increasing FeCl3 concentrations; (b) 9 g l−1,magnification 1290×; (c) 18 g l−1, 1180×; (d) 27 g l−1, 1940×.

were evaluated by means of an electrical circuit consisting ofa Metrel potentiometer (0–230 V, 50 Hz), a digital MultimeterEscort 170, a Supertester 680 G ammeter and six terminals. Thetemperature on the textile surface was measured by means of aRaytek Raynger ST infrared thermometer.

3. Results and discussion

Viscose is a cellulose textile fibre largely used for conven-tional and technical application, obtained by cellulose regen-eration from carbon disulphide solution. The classical viscosefibre morphology shows a smooth surface profile with a typicalmulti-lobe cross-section due to the production process. A set ofconductive viscose fabrics was prepared by wet impregnationand successive polymerisation of pyrrole in vapour phase ontocellulose in a closed vessel at 60 ◦C.

At room temperature pyrrole is a liquid, with boiling temper-ature 130 ◦C. The enthalpy of vapourization can be calculated,as a function of the temperature, by the following formula (1):

�vH◦ = A exp(−βTr)(1 − Tr)

β (1)

where A = 62.7 kJ mol−1, β = 0.2964, Tr is the reduced tempera-ture (Tr = T/Tc), T the actual temperature and Tc = 366.7 ◦C is thecritical temperature of pyrrole [14]. The monomer molar frac-

tion calculated by means of the Antoine equation at 60 ◦C and1 bar was about 9% [15].

The morphology of pristine viscose is shown in Fig. 1a. TheVPV samples, analysed by SEM, shows a well-deposited layerof conducting polymer on the fibre surface (Fig. 1). At lowconcentrations of FeCl3 (9 g l−1) in the impregnation solution(oxidant + doping agent), a thin layer of polymer was deposited(Fig. 1b). The increase of the oxidant concentration (18 and27 g l−1) produces a thicker and less homogeneous layer of Ppyrdeposited on the fibres as shown in Fig. 1c and d.

In Fig. 2 the different morphologies of the fibres polymerisedin vapour and liquid phases are compared. The figure showsthat the vapour deposition method produces fibres with a uni-form conductive layer, while cellulose samples prepared withliquid polymerisation show Ppyr aggregates on the fibre surface(Fig. 2b). The cross-section images of the cellulose/Ppyr fibresobtained by transmitted light microscope on both VPV and VPLsamples are reported in Fig. 2c and d. The conducting fabricsprepared with polymerisation in liquid phase show a completeand homogeneous penetration of polypyrrole in the fibre bulk(see Fig. 2d), while VPV samples show a partial penetration ofPpry into the fibres with a concentration gradient from surface tothe centre (Fig. 2c). This morphological difference depends onthe polymerisation condition: in aqueous solution the celluloseswells and both monomer and reagents can uniformly penetrate

382 L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386

Fig. 2. SEM pictures of cellulose/Ppyr textiles prepared with FeCl3 concentrations of 9 g l−1 (a) VPV sample, magnification 5850×, and (b) VPL sample, magnification5670×; transmission light microscopy of cross-section fibres: (c) VPV 500× and (d) VPL, 200×, samples obtained with the same oxidant concentration (9 g l−1).

into the core of the fibres were polymerisation occurs, while inthe vapour phase polymerisation takes place from the exteriorto the core. The diffusion and the polymerisation of Pyr into thefibre core are slow and inhomogeneous because of the obstruc-tion of the already present polymer.

The conjugated polymer amount in the textiles was estimatedby means of the weight increase of the fabrics. The weightincrease of a VPV sample prepared with an oxidant concen-tration of 27 g l−1 is 95% and it is due to the presence of conju-gated polymer, dopant and oxidant traces. In Fig. 3 the weightincreases as a function of FeCl3 concentration in the impregna-tion solution are reported for both VPV and VPL textiles. Forlow oxidant amounts the weight increases are similar for VPLand VPV samples; for FeCl3 concentration up to 10 g l−1 thetextiles prepared in vapour phase are heavier due to the prepa-ration method that allows a better penetration of oxidant anddopant inside the fibres.

The thermal properties of viscose/Ppyr composites were stud-ied by DSC. In Fig. 4 the DSC thermograms of pristine viscose,pure Ppyr synthesised in vapour phase, oxidant and dopant pow-der are reported. Pure EMPA viscose shows a quite narrow peakof decomposition at 344 ◦C with an enthalpy of decomposition,determined by peak integration, of −130.13 J g−1. DSC anal-ysis of pure Ppyr displays a two-step peak of decomposition:the first centred at 256 ◦C and the second, very broad, at 390 ◦C

(not shown in Fig. 4 because outwith the considered range).In addition, two endothermic peaks at 114 and 162 ◦C indi-cate the presence of dopant and FeCl3, respectively, in the Ppyrbulk.

Fig. 3. Weight increase as a function of FeCl3 concentration in the impregnationaqueous solution for VPL (�) and VPV (�) samples.

L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386 383

Fig. 4. Comparison between DSC analysis of pure viscose, oxidant, dopantreagent and pure Ppyr synthesised in vapour phase.

Fig. 5 shows DSC analysis of VPV samples prepared withdifferent concentration of FeCl3 in the impregnation solution.A progressive broadening of the cellulose decomposition peakand a shift toward lower temperatures occur by increasing FeCl3concentration until 4.5 g l−1. When the oxidant amount exceeds9 g l−1, the decomposition peak becomes very large with a max-imum at around 254 ◦C. In addition a marked exothermic eventoccurs at 301.6 ◦C, which is probably due to the cellulose inter-action with residue from both the dopant and the oxidant. Thisbehaviour has been observed in cotton thermal analysis, andattributed to a base-catalysed cellulose dehydration reaction inpresence of ions such as potassium [16].

The Ppyr excess was removed after polymerisation from thefibre surface by domestic washing at standard conditions. TheVPV(9) sample was washed at temperatures varying from 30 to60 ◦C and DSC analysis was carried out with the aim of testing

FF

Fig. 6. Comparison of DSC analysis of VPV(9) sample after different washingcycles.

the thermal behaviour of the clean fabric. With an increase ofthe washing temperature, the endothermic decomposition peakshifts to 329 ◦C, and the temperature of the exothermic peakincreases from 300 to 333 ◦C (see Fig. 6). After a washingcycle at 60 ◦C the exothermic peak completely disappears. Theincreased thermal stability of the textiles after washing indicatesthat reversible interactions between reagents and substrate occurduring the vapour polymerisation process.

The FT-IR spectrum of viscose shows the typical features ofcellulose, a broad peak at 3318 cm−1 due to (O H)str, a peak at2886 cm−1 due to (C H)str and a large absorption between 1136and 933 cm−1, which results from the contribution of variousfunctional groups, namely (C C)str, (C O)str and (C O C)str.It is worth noting the small peak at 1637 cm−1 is due to a partialoxidation of the alcoholic to carbonyl functional groups as aresult of natural ageing of cellulose [17].

The spectral features of pure Ppyr are also well known inliterature [18–23], the spectrum shows (C C)str absorption at1550 cm−1, (C C)str at 1450 cm−1, (C N)str at 1300 cm−1 andthe characteristic bending modes (565, 783, 1036, 1170 cm−1).In Fig. 7 the FT-IR spectra of VPV fabrics prepared with increas-ing FeCl3 concentration are reported. Cellulose absorptions arevisible in VPV samples even at high oxidant concentration. ThePpyr peak at 1550 cm−1, which is not superimposed to cellulosefeatures, strongly increases with FeCl3 amount; the integrationof this peak can be correlated with the weight increase (Fig. 3),a

cas(pb

iV

ig. 5. DSC analysis of pure viscose and VPV samples prepared with increasingeCl3 concentration.

nd can be used as a method of quantitative analysis [12].WAXD measurements were performed on pure EMPA vis-

ose, VPL(90) and VPV(9) fabrics; the textiles were cut, mixednd pressed to obtain randomly oriented samples. The viscosehows the typical profile of cellulose II crystalline modificationsee Fig. 8). The crystalline structure of the cellulose matrix isreserved both in the viscose/polypyrrole composites preparedy liquid phase and in vapour phase.

The Lorentz-corrected SAXS scattering profiles registeredn the perpendicular direction to the fibre axis, for the EMPA,PL and VPV samples, are reported in Fig. 9. The plot of the

384 L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386

Fig. 7. FT-IR spectra of pure viscose and VPV samples prepared with increasingFeCl3 concentration.

Fig. 8. WAXD profiles of pure EMPA viscose, VPL and VPV.

Fig. 9. SAXS: Lorentz-corrected intensity-scattering profiles registered in theperpendicular direction to the fibre axis of pure EMPA viscose, VPL and VPV.

Fig. 10. SAXS: intensity-scattering profiles registered in the parallel directionto the fibre axis of pure EMPA viscose, VPL and VPV.

EMPA sample shows a maximum relative to a periodicity (L)of the system. The increase of the scattering intensity and rela-tive sharpening of the periodicity peak, registered for the VPVsample, is evidence of the distribution of polypyrrole compo-nent in the amorphous phase of the cellulose. Similar L valuesof 14.0 and 13.5 nm were calculated for the EMPA and VPVsamples, respectively. The broadened profile registered for theVPL fabric, is probably due to the large amount of large domainsof polypyrrole stuck on the fibre surface, as evidenced by SEManalysis [12]. Anyway, a small shoulder was evidenced in theangular position where the EMPA sample showed the maximumscattering.

A continuous scattering profile was evidenced for all samples,when investigated in the parallel direction to the fibre axis (seeFig. 10). However, while the scattering profiles of the EMPAand VPL samples were overlapped, a meaningful increase inthe scattering intensity was evidenced for the VPV sample. Bysubtraction of the pure EMPA viscose profile from that of theVPV fabric, the scattering relative to the Ppyr component wasobtained and elaborated according to the Hosemann-Joerchelapproach [24,25]. The values of hm and h0 were calculated fromthe plot reported in Fig. 11. hm corresponds to the maximum of

Fo

ig. 11. SAXS: Hosemann-Joerchel plot relative to the polypyrrole componentf VPV sample.

L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386 385

the curve, h0 is the intercept of the tangent in the flex point, inthe right side of the curve, with h-axis.

The ratio of these two values gives the M* parameter, bymeans of which it is possible to derive the average radius of theparticles ym and the polydispersity gy:

ym = 0.96

hm

9.6 − 2M∗√

7.5 − M∗ (2)

gy =√

M∗ − 2.1

9.6 − 2M∗ (3)

The value of the average interparticle distance (lm) can beobtained by:

lm = 2π

hm(4)

The values of 1.5 and 8.0 nm were calculated for ym andlm, respectively. The calculated gy value equal to 0.75, is anindication of the high distribution of the particle size.

Mechanical and physical tests were performed on the fab-rics in order to evaluate the most significant textile properties.Comparison has been performed between pure Viscose, VPVand VPL samples. Tensile strength and elongation of the fabricsare shown in Table 1. Variations occur on VPL samples as acphodcdiitfa

mtfsPat

Fig. 12. Curves of current vs. applied voltage for different VPV samples.

The electrical conductivity of VPV samples was determinedin a conditioned laboratory (20 ◦C, 65% R.H.). Washed sampleswere cut to the same size (6 × 6 cm.), coated with silicon-basedoil, and placed in the electrical circuit with six equidistant termi-nals. The electrical properties decrease by 70–80% in 2 weeksdue to atmospheric ageing, after this time the conductivity is sub-stantially unchanged. The application of siliconic oil as a coatingon the conductive fibres sensitively slows down the resistanceincreasing. The conductivity loss is essentially an oxidation pro-cess due to oxygen rather than to either the light or heat action,because the samples were stored in a conditioned dark box. Volt-age was progressively increased up to 200 V or stopped whenthe system started decomposing due to heat generated by Jouleeffect. The resulting graph current–voltage, for VPV system,is reported in Fig. 12, and has a linear fit until VPV(9) and anexponential fit for higher FeCl3 concentrations. It is worth notingthat the current increment depends on both the amount of Ppyrembedded in the fabric and the doping level of the polymer andit is not linearly related to the oxidant concentration in the solu-tion. Thus the huge change in conductivity due to the increase ofthe oxidant concentration is probably due to the higher amountof Ppyr embedded and to its doping level as well. Fig. 13 showsthe behaviour of temperature versus voltage for the consideredsystems, whose shapes can be fitted by exponential curves withthe following general equation:

T

TC (22.5

S Wa

V –V –V CoV DisV CoV Dis

onsequence of the polymerisation reaction. In the liquid phaserocess, the cellulose structure remains unchanged even forigh Ppyr loadings, according to microscopic analysis. On thether hand, the mechanical properties of VPV samples stronglyecrease by effect of the higher oxidant concentrations. In theonducting textiles prepared in vapour phase, the FeCl3 oxi-izes the cellulose structure more effectively, because with thempregnation method non-negligible amounts of catalyst remainn the final polymer. Drying after impregnation also increaseshe local concentration and thus the oxidation reaction on theabric. No significant differences were found between the weftnd the warp directions, because of the plain weave.

Both VPV and VPL samples have good fastness perfor-ances to washing, light exposure and dry rubbing, particularly

he fabrics prepared in vapour phase. However, a poor rubbingastness has been observed to moist tests (see Table 1). A pos-ible explanation stems from a weak bond formation betweenpyr and cellulose, due to an intermediate layer of the oxidantnd the dopant. The polymer detachment by rubbing can be dueo this layer in moist conditions.

able 1omparison of mechanical and physical properties of viscose, VPV(9) and VPL

amples Strip strength

Strength at break (N) Elongation at break (%)

iscose weft 381.79 24.13iscose warp 311.53 15.41PV weft 139.83 13.32PV warp 96.61 9.45PL weft 358.08 24.39PL warp 312.54 20.18

= T 0 + ae−kV (5)

), in weft and warp direction

shing fastness Light fastness Rubbing fastness

– –– –

lour degradation: 4–5 Colour degradation: 6–7 Dry: 4–5charge colour: 5 Moist: 1lour degradation: 4–5 Colour degradation: 6-7 Dry: 3–4charge colour: 5 Moist: 1

386 L. Dall’Acqua et al. / Synthetic Metals 156 (2006) 379–386

Fig. 13. Plot of temperature vs. applied voltage for different VPV samples.

where V is the applied potential, T0 the initial temperature andT is the final temperature.

4. Conclusions

Chemical vapour phase deposition of conducting polypyrroleis a suitable process to produce electro-conductive cellulose tex-tiles with low reagents wastes. The process, studied for viscose,although generally applicable, consists of two steps: (1) fabricimpregnation with an aqueous solution of oxidant and dopantand subsequent drying; (2) exposition to pyrrole vapour andpolymerisation.

The fabrics polymerised in vapour phase (VPV samples)show highly uniform Ppyr coating on the fibre surface, witha partial penetration of polypyrrole inside the amorphous zonesof fibre bulk.

The morphology and both the structural and electrical prop-erties of conducting viscose prepared by liquid phase (VPLsamples) and vapour phase depositions have been compared.VPV samples show a more uniform polypyrrole layer withoutaggregates on the fibre surface than VPL. Polypyrrole pene-tration into the fibre bulk is quite complete for VPL samples,whereas only a partial penetration was observed in VPV sam-ples, and the segregation of a part of oxidant and dopant insidethe fibres was highlighted by DSC analysis.

t

SAXS results evidence the presence of nanoparticle dispersionof polypyrrole in the cellulose matrix for the VPV samples. Onthe other hand the scattering profile obtained for VPL fabricsuggested the presence of a continuous phase characterised bylarge domains of polypyrrole.

Fastness performances to washing, light exposure and dryrubbing were consistent for textile uses, while poor fastness hasbeen observed to moist rubbing tests. A decrease in strength wasobserved on the VPL samples during the FeCl3 impregnation.

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