UV curable nanocomposites with tailored dielectric response

Abstract

Photopolymerization or UV curing represents a fast and solvent-free technique to obtain polymer-based composites, being one of the main methods used in lithographic processes, surface coatings and the manufacture of integrated circuits. This work reports on the development of UV curable barium titanate/ polyurethane acrylate (BaTiO3/PUA) composites with varying ceramic contents in order to tailor the dielectric response of the material. A good dispersion of the ceramic particles within the polymer matrix is obtained, together with a thermal stability of the composites up to 160 ºC. The inclusion of the BaTiO3 nanoparticles onto PUA photoresin slightly decrease the glass transition temperature of the organic matrix. The obtained white coloured films show mechanical flexibility with elongations at break up to 25%. The increase of BaTiO3 content leads to an increase of the dielectric constant up to 25 for sample with 65 wt% content. The size of the BaTiO3 nanoparticles proved not to be a key factor on determining the dielectric constant value of the composite for filler sizes up to 100 nm. Theoretical studies demonstrate that the model that better predict the behaviour of the BaTiO3/PUA composites is the Tinga model, giving insights on the physical phenomena determining the dielectric response of the materials. Thus, high dielectric UV curable composites are obtained suitable for microelectronics applications