Lattice Boltzmann method simulations of swelling of cuboid-shaped IPN hydrogel tablets with experimental validation

The swelling behavior of IPN hydrogel tablets in the shape of cuboid or rectangular parallelepiped tablets in contact with buffer solutions at different pH and temperature conditions were estimated by a three-dimensional multiple-relaxation-time lattice Boltzmann (LB) model. Adsorption isotherms were obtained experimentally for tablets of IPN hydrogel formulation immersed in buffer solution at 298.15 and 310.15 K at pH equal to 4.48, 7.25, and 8.225, and those of copolymer hydrogel formulation at 298.15 K at pH equal to 4.48, 7.25, and 8.225. A computational method based on an LB model is used to simulate the hydrogels swelling, employing dimensionless units of length and mass. The discretization error estimation of the computational simulations was calculated by the grid convergence index method. Excellent correlations were achieved between the computational data and experimental values of mass swelling percentage, achieving coefficients of determination equal to or higher than 0.993 for the finest grids. The equilibrium diffusion coefficient at low pH values is higher than at large pH values. The simulations allowed us to estimate the equilibrium diffusion coefficient for each case; a qualitative property of the polymer, and to observe how the inner regions of a sample are hydrated in the time domain, both of which cannot be done experimentally.