Viscoelastic properties of a 3D-Printable high-dielectric paste with surface-modified BaTiO3

In this study, a polystyrene-block-polyisoprene-block-polystyrene (SIS) based dielectric paste was fabricated using barium titanate (BT) as dielectric filler in order to produce organic-inorganic composites for 3D dispenser printing applications. Since a high loading of inorganic filler is generally required to obtain high dielectric properties, the surface of BT was modified with two different phosphonic acids having functional groups resembling the groups contained in the block copolymer, in order to achieve a high compatibility between the filler and the polymer matrix. Upon incorporation of 80 wt% of BT in SIS, the dielectric constant was found to be approximately 3 times higher than that of bare SIS. The surface modification of the filler enhanced its dispersion within the polymer matrix, as confirmed by the surface morphology of the composite film at a high filler content. The desired viscoelasticity was achieved through the fine-tuning of the total solid content, and consequently, the potential application of the composite as 3D printable paste was demonstrated through the formation of a layer-by-layer printed structure on a flexible substrate.