HERRMANN JUNIOR, P. S. de P.

MANZOLI, A.

PASCHOALIN, R. T.

STEFFENS, C.

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Study of polyaniline films morphological properties with AFM in optical pH sensors.

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ICAM2009We hereby certify that the work"Study of polyaniline films morphological properties with AFM in optical pHsensors" (1564)by the authors Rafaella T Paschoalin, Clarice Steffens, Alexandra Manzoli and Paulo Sergiode Paula Herrmannwas presented on Poster form byALEXANDRA MANZOLIin the 11th International Conference on Advanced Materiais -ICAM 2009,occurred in Rio de Janeiro-RJ between september 20th to september 25th, 2009.Rio de Janeiro-RJ, september 25th, 2009.Guillermo Solorzano ElisaSaitovitchChairman ICAM2009 Program Chair11 til International Conferenceon Advanced MateriaisRio de JaneirQ Sra:dlICAM2009 SePt,ember20 . 25 I'Study of polyaniline films morphological properties w;th AFM in optical pHsensorsR.T..Paschoalln'l", C. Steffens (1) , A. Manzoli'" and P.S.P.Herrmann Jr.(W(1) Alan G. Macülarmid Institute for Innovation and Business and National NanotechnologyLaboratory for Agribusiness (LNNA), Embrapa Agricultural Instrumentation, P. O. Box 741, 13560-970, São Carlos, SP, Brazil, e-mail: herrmann@cnpdia.embrapa.br ;(2) Universidade Central Paulista, UNICEP, P. O. Box 511,13563-470, São Carlos, SP, Brazil.* Corresponding author.Abstract - In Ihis work, lhe effecl of pH was investigaled on lhe morphological properties of oplical pH sensors wilh Ihin filmsof polyaniline (PANI) as aclive layer. The oplical pH sensors were prepared by lhe line-patterning lechnique on PET (poly(elhylenelerephlhalale) substrate and coated wilh Ihin film of polyaniline emeraldine oxidalion state-Hcl (PANI-HCI) salt, oblained by "in sítu"polymerizalion melhod. The resulls showed that lhe pH has greal influence in lhe polymer layer morphology of Ihese sensors.The polyaniline (PANI) has appropriate optical properties for optical pH sensors. The PANI pHchange sensitive electronic absorption band is very broad [1] and its optical pH sensors are suitable tomeasurement in the ranqe of pH 2-12 [2]. This way, the optical pH sensors with thin films of PANI as pHsensing layer representa an interesting alternative to indicator-based sensor films due to their advantages interms of size, costs, and response time. .In this work, optical pH sensors were prepared by the line-patterning technique [3] on PET substrateand coated with a thin film of polyaniline by "in situ" polymerization method. The pH effect on morphologicalproperties of these sensors was analyzed with Dimension V (Veeco) atomic force microscope. The opticalpH sensors were immersed for five minutes in three different pHs (2, 7 and 12) and the 3D images areshowed in the Figure 2. Ali images were obtained in tapping ™ mode w!th scan rate of,1 Hz. The root-mean-square roughness (Rms) and rriean roughness (Ra) were calculated using WSxM 4.0 software from NanotecElectronica S.L. (copyright© November 2003). .It can be observed that optical sensors in pH 2 showed a higher value of roughness than that in pH 7and 12 (Figure 1). It was also verified that Ra and Rms values were very close. The PANI films morphologywere globular, showing a more flat surface for the pH 7 (Figure 2), which is in agreement with the lowestroughness value obtained with this pH. These results show that the pH has great influence in these sensorspolymer layer morphology.!:~:l..•.......··•.·b-_11••o.vpm0.001'11I...(a) (b) (c)Figure 1: Average roughness (Ra) Figure 2: 3D images of Ihin films of polyaniliQe on .optical pH sensors: a) pH 2. b) pH 7and rool mean square (Rms) 'in and c) pH 12. .differenl pH.References[1] D. Bloor, A. Monkman, Synth. Met. 21 (1987) 175. .[2] U.w. Grummt, A. Pron, M. Zagorska, S. Lefrant, Anal. Chim. Acta, 357 (1997) 253.[3] E.C. Venancio, L.H.C. Mattoso, P.S.P. Herrmann, A.G. MacDiarmid, SensoActuators B 130 (2008) 723 .."

Study of polyaniline films morphological properties with AFM in optical pH sensors.

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