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INFLUENCE OF FILLER DISPERSION ON THIN FILM POLYMER COMPOSITES SENSING PROPERTIES

Luigi Quercia 1Fausta Loffredo 2Girolamo Di Francia 1

1. Italian National Agency for New Technologies, Energy and the Environment (ENEA), Via del Vecchio Macello, Portici 80055, Italy
2. University of Naples "Federico II", Department of Physical Sciences, Napoli, Italy

Abstract

Carbon black/polymer composite are very interesting materials already used to produce vapor sensors. Sensor responses are due to vapor absorption properties of an insulating polymer whose electrical properties are modulated by a conductive "filler".
In this work we produce thin composite films characterized by different grade of dispersion of carbon black in polymer matrix (Poly(methyl-methacrylate), Poly(2 hydroxy-ethyl-methacrylate) and atactic poly(styrene)). These samples are obtained changing some process parameters (viscosity of polymer solution and type of spinning deposition) or using different conductive filler types. We have used different fillers all made of carbon, but with different particle sizes (from micrometers to nanometers), structure and chemical functionalization. In particular, we have used commercial carbon blacks, multi-walled carbon nanotubes and home made carbon nanoparticles. In order to improve the dispersion of the filler in the polymeric solution we have modified commercial carbon black by a Fenton type oxidation. In order to evaluate the filler size influence we have prepared carbon nanoparticles (5-20 nm) obtained by flame synthesis.
Size distribution of filler in polymer suspension and deposition method strongly influence homogeneity and conductivity of corresponding polymer composite films and finally their sensing properties.
We study filler dispersion in polymer matrix by dynamic light scattering, optical and electronic scanning microscopy, profile analysis and 4 point probe measurements. This has allowed to investigate about the influence of different fabrication parameters on film morphologies (homogeneity, grade of filler dispersion, size of filler aggregates) and conductivity. Testing to different VOCs the sensor devices, will show the influence of different morphology on the characteristics of the sensors responses (sensitivity, selectivity, response and recovery time).

 

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Presentation: oral at E-MRS Fall Meeting 2004, Symposium A, by Luigi Quercia
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-28 18:36
Revised:   2009-06-08 12:55