Influence of filler dispersion on thin film composites sensing properties

In this work, we produce thin composite films characterized by different grade of dispersion of carbon black in polymer matrix (Poly(methyl-methacrylate) and Poly(2 hydroxy-ethyl-methacrylate)). 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 order to improve the dispersion of the filler in the polymeric solution, we have modified commercial carbon black by a Fenton type oxidation. Size distribution of filler in polymer suspension and deposition method strongly influences homogeneity and conductivity of corresponding polymer composite films and finally their sensing properties. We study filler dispersion by dynamic light scattering, optical and scanning electronic microscopy (SEM). This has allowed investigating 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.