DENSITY DISTRIBUTION OF CALCIUM-INDUCED ALGINATE GELS - A NUMERICAL STUDY

Charged polysaccharides often form hydrogels in the presence of cation s. In many applications the polymer network density distribution and a ssociated physical properties are of major practical importance. Depen ding on the detailed conditions, the resulting gel density may vary fr om fully homogeneous to strongly inhomogeneous. We have established a simple set of coupled chemical reaction-diffusion equations to model t he gelling process of calcium-induced alginate gels. The necessary alg orithms for numerical solution of the resulting simultaneous parabolic differential equations have been developed both for one-dimensional m odels and three-dimensional models with cylindrical or spherical symme try. The algorithms make use of the Crank-Nicolson implicit finite dif ference method. The results of the numerical analyses of the gel forma tion can be divided into several different regimes depending on the ph ysical and chemical parameters of the alginates and the cations. The n umerical results are in good agreements with reported experimental res ults. (C) 1995 John Wiley & Sons, Inc.