Investigation of the effect of surface phosphate ester dispersant on viscosity by coarse-grain modeling of BaTiO$_3$ slurry.

To understand the role of phosphate ester dispersant, we investigated the rheology of a BaTiO$_3$ slurry. For the model case, a coarse-grain molecular dynamics (CGMD) simulation was performed with the butyral polymer didodecyl hydrogen phosphate (DHP), in the toluene/ethanol solvent. By systematically analyzing the effect of DHP from an atomic-scale first principle and from all-atom MD to micro-scale CGMD simulation, we investigated how the adsorption of a DHP dispersant on a BaTiO$_3$ surface affects the microstructure rheology of a BaTiO$_3$ slurry. The first-principle and all-atom MD simulation suggests that DHP molecules prefer to locate near the BaTiO$_3$ surface. CGMD simulation shows a reduction in viscosity with an increase in dispersants, suggesting that the dispersant population near the BaTiO$_3$ surface plays a key role in controlling the rheology of the BaTiO$_3$ slurry. In this study, we propose an approach for understanding the BaTiO$_3$ slurry with molecular-level simulations, which would be a useful tool for efficient optimization of slurry preparation.