Nanosize Surface Electromodification of Carbon Fibers by Conductive Polymers  and Their Characterizations Prof.Dr.A.Sezai.SARAÇ Istanbul Technical University Department of Chemistry & Polymer Science and Technology Maslak 80626 Istanbul,Turkey

of polymeric composites Carbon fiber reinforcement of polymeric composites Carbon fibers(CF) are used in composites(i.e.,PAN based CF) in order to produce materials of lower density and greater strength. advanced structural materials: aircraft, spacecraft, and suspension bridges – The most widely used composite material in tactical aircraft is a carbon fibre/epoxy A polymeric ‘interface’ acting as a coupling agent, improve the interfacial properties between reinforcing (carbon) fibers and the polymeric matrix . 5-7μ A.S. Sarac, A. Bismarck, E. Kumru, J. Springer,Synth. Met. 123 (2001) 411-423 E.Kumru,J.Springer,A.S.Sarac,A.Bismarck.,  Synth. Met.  123(2001)391-402

Biosensor Appl. Electromodified carbon fibers also have potential for biosensor applications as microelectrodes -working in small volumes of solutions- Homogeneous Conductive Polymer coated -surface functionalities is suitable for the miniaturization of electrode system for a particular analyte. Several copolymer and polymer coated electrodes(Cz based) were shown to be an effective disposable microelectrode system for the determination of p-aminophenol at low detection limits M. Jamal, E. Magner, A.S.Sarac, Sensors and Actuators 97 (2004)59-66

Carbon Fiber Reinforcement applying force to a composite material, the brittle matrix cracks at low stress levels > fibres take over Woven fiber Epoxy resin –polymer matrix

The structure & comp. of copolymeric films, plays an important role on the final properties of modified carbon surface The coating parameters & characterization of these functionalised thin films are important . Improving the interfacial adhesion Advanced Composites- Interfacial adhesion control the level of fiber/matrix adhesion A.S.Sarac,M.Serantoni,,A.M.T.Syed,V.J.Cunnane ,Appl.Surface Sci.,(2004) 229,13-18 A.S.Sarac,A.M.T.Syed,M.Serantoni,,V.J.Cunnane J.Mater.Sci.Lett.(2004) 39,2945-2950

Surface Analysis (the characterizations of electrografted thin polymeric film ~10-50nm film characterizations-Fast and simple for org. thin film coating & charac. -Nanosize Change of functionality of surface) Spectroscopic Functionalities FTIR-ATR Raman Composition - XPS,EDX,FIBSIMS Electrochemical Impedance Spectroscopic studies Morphological SEM AFM

AFM of Electrogrowth of P[Cz-co-AAm] onto HOPG Graphite Higher scan rates (100 mV/s) : thin (hf  22 nm) coatings . Lower scan rates (≤ 50 mV/s) ~50 nm A.Bismarck,A.Menner,J.Barner,A.F.Lee,K.Wilson, J.Springer,J.P.Rabe,A.S.Sarac, Surface Coat .Tech. 145(2001)164-175

Current density vs cycle number (▪): 1. 53V (●): 1 Current density vs cycle number (▪): 1.53V (●): 1.04 V and the coating thickness (▫) from the ellipsometric angles

Galvanostatic vs. Cyclic voltammetry polymerization rate vs.film growth. CV : Galvanostatic process thin coating (hf  15 nm) & smoother (RMS = 13 nm),

polyethylenedioxythiophene (PEDOT) AFM of Untreated Carbon fiber(r~5.6 μ) polyethylenedioxythiophene (PEDOT)

Polyterthiophene/CF

Electrocoating of polytetrathiophene onto carbon fiber by cyclic voltammetry 10mM TEABF4/MeCN. 10 cycles at 100mVs-1 2 mM Polytetrathiophene in 10 mM TEABF4 / PC , 20 mV/s ,RMS 50 nm (1mm2) 5 scan SARAC,A.S.,EVANS,U.,SERANTONI,M.,CUNNANE,V.J.,Carbon 41,14 (2003) 2725-2730

polytetrathiophene formation on the surface

polymethylcarbazole

Poly[MCz] on CFME in 0.1 M NaClO4 in PC at 100 mV/s.

Poly[MPy] on CFME in 0.1 M NaClO4 in PC at 100 mV/s.

Poly[MPy-co-MCz] on CFME in 0 Poly[MPy-co-MCz] on CFME in 0.1 M NaClO4 in PC at 100 mV/s, [MPy]& [MCz]=0.001 M

Poly[MPy-co-MCz] in monomer-free solution Poly[MPy-co-MCz] in monomer-free solution. a) 10 mV/s, b) 20 mV/s, c) 50 mV/s, d) 100 mV/s, e) 200 mV/s in a 0.1 M NaClO4 / PC solution. All samples were subsequently cycled 8 times

Scan rate dependence of the copolymer film : Plots of anodic and cathodic peak currents vs. the square root of scan rate Inset: : change in anodic and cathodic peak currents with scan rate in monomer free solution of 0.1M NaClO4/PC Randles Selvic ip = (2.69 x 108) n3/2 A C D1/2 ν1/2

Effect of feed ratio of monomers on current ,solid state conductivity and yield.

Comparison the peak current densities of electro-growth of the copolymer films obtained by CV and solid state conductivity in different monomer ratios

Anodic peak current densities of Poly[MPy-co-MCz] in different electrolytes using multiple (50 cycles) in monomer-free solution at 100 mV/s, [MPy] &[MCz]=0.001 M.

Poly(N-vinylcarbazole-co-Vinylbenzenesulfonic acid) Ungrafted CF, P[NVCz-co-VBSA] grafted CF 100 mA 4 hrs 200mA 2 hrs Element   NVCzVBSA2 NVCzVBSA3 C 76.57 85.83 N 2.84 3.76 O 15.20 9.03 S 2.83 0.15 Element   NVCzVBSA2 NVCzVBSA3 C 76.57 85.83 N 2.843 3.76 O 15.2 9.033 S 2.825 0.147

Poly[NVCz-coVBSA] NVCzVBSA3

Reflectance FTIR of thin carbazole copolymer film on CF

Poly[Methylthiophene-co-carbazole]

Reflectance FTIR & EDX of electrografted P[MeTh-co- Cz] thin copolymer film A.S.Sarac, J.Springer., Surface Coat.Tech.(2002) 160,227-238

Raman Spectra 1330 cm-1 C=C , 1567cm-1 C-C ring

XPS P[Cz-co-MeTh] Carbon fiber C=S C-N C=O P[Cz-co-MeTh] Carbon fiber at different initial comonomer feed ratios A.S.Sarac, M.Serantoni, T.Syed, J.Henry, V.J.Cunnane, J.B.McMonagle, Appl.Surface Sci.. 243(1-4)( 2005) 183-198 A.S.Sarac, A.MT.Syed, M.Serantoni, J.Henry, V.J.Cunnane, J.B.McMonagle. Appl.Surface Sci. Sci.222,1-4(2004) 148-165

Reflectance FTIR of vinyl group in copolymer

Poly[MeTh-co-NVCz]

Electrocoated carbon fibre single fibre pull-out test Electrocoated carbon fibre single fibre pull-out test. a)The fibre was partially pulled-out of the electrodeposited coating. b) fibre completely pulled-out of the electrodeposited coating. The adhesive strength CF/PMMA matrix resulted in 100% improved in thin and homogeneous PMMA coatings. (the interfacial shear strength not so good in thicker coatings) So, electrocoating of MMA can improve the interfacial performance of a carbon fibre reinforced PMMA model composite.

% concentration (determined from XPS ) versus cps (determined from FIBSIMS measurements ) P[NVCz-co-MeTh] M.Serantoni, A.S.Sarac,D.Sutton,V.J.Cunnane, Surface Coat.Tech..( 2005) (in press)

Nanosize Surface chemistry & Morphology of CP electrografting onto Carbon Foam & CF surface &Electrochemical Impedance Their Applications Thin conductive polymer films can be covalently electrografted onto the CF Surface structure and composition can be analysed in nanoscale (> 20 nm)(XPS,Raman ,FTIRATR) Surface morphology (SEM,AFM) improve the interfacial shear strength reinforcement appl. biosensor applications

Istanbul Bosphorous Asia-Europe                                                   Istanbul Bosphorous Asia-Europe sarac@itu.edu.tr http://atlas.cc.itu.edu.tr/~sarac/ http://www.kimya.itu.edu.tr/saraca/