The Deswelling of IPN Hydrogel Tablets by Lattice Boltzmann Method

The deswelling of cylindrical copolymeric and interpenetrating-polymer-network (IPN) hydrogel tablets was simulated by employing the lattice Boltzmann (LB) method. Polyvinyl alcohol (PVA) was employed as an interpenetrated phase. The mass concentration of the diffusing species released from the polymer network as a function of time was obtained experimentally at 298.15 and 310.15 K. The computational method utilized to simulate the deswelling of hydrogel samples is based on a two-dimensional multiple-relaxation-time (MRT) LB model with axisymmetric symmetry. The discretization errors of the simulations were calculated using the grid convergence index (GCI) method. The computational method simulated the deswelling behavior with high reliability according to the experimental data, reaching coefficients of determination equal to or greater than 0.98500 for the finest grid in each case. These simulations allowed us to obtain the equilibrium diffusion coefficient and, furthermore, to observe how the normalized swelling concentration profile of two samples with the same formulation at different temperatures changes during the deswelling process, which is not possible experimentally. The PVA as an interpenetrated phase in hydrogel samples of acrylamide slows down the deswelling process and reduces the effect of the temperature on the extrapolated equilibrium diffusion coefficient during deswelling according to the copolymeric samples.