Effect of dispersant viscosity for self-assembly process of barium titanate aggregates in material texture of polyvinylidene fluoride composites —evaluation of multifractal dimension (<i>D<sub>q</sub></i> [<i>q</i> = 0, 1, 2]) and dielectric properties—

In this paper, the properties of the barium titanate (BT)/polyvinylidene fluoride (PVDF) composites were controlled by the self-assembly of the BT secondary particle groups. The self-assembled BT/PVDF composites of 5–20 vol.% BT were prepared with the difference in the viscosity of polyethylene glycol (PEG) of dispersants involved in the self-assembly process. The multifractal properties and dielectric properties of the self-assembled BT/PVDF composites were investigated with controlling by the formation of the self-assembled BT secondary particle groups. The dielectric constant (ε′) increased with an increase in the average secondary particle area (S) of the BT particles. The S increased with an increase in the viscosity of PEG; whereas, the ε′ decreased with the increase in viscosity. The multifractal analysis indicated that the distribution of self-assembled BT secondary particle groups was affected by PEG viscosity. The sample with PEG1000 had aggregates with a BT/PVDF/BT heterointerface, the sample with PEG20000 had agglomerates with a BT/BT interface, and the sample with PEG2000 had both, aggregates and agglomerates. The BT/PVDF/BT heterointerface in the BT aggregates played an important role in improving the dielectric properties of the BT/PVDF composites. Overall, the viscosity of the dispersant affected the self-assembly process as well as the ε′. It was suggested that the multifractal properties and dielectric properties were controlled by the self-assembly of the BT secondary particle groups.