Calcium alginate barrier films modified by montmorillonite clay

The goal of decreasing the permeation of small molecules through calcium alginate films is addressed by incorporating small amounts of montmorillonite clay into the polymer. Incorporation is achieved by (i) blending up to 3 wt% pre-exfoliated montmorillonite into sodium alginate polymer solutions, (ii) casting thin films, (iii) cross-linking the chains with calcium chloride solution into insoluble calcium alginate, and (iv) drying the resulting cross-linked materials. Exfoliation and dispersion of the montmorillonite platelets is assessed by light scattering and small-angle X-ray scattering. The barrier properties of the impregnated films were gauged by permeation of benzaldehyde using a Hanson-Research diffusion cell. Decreased permeability is found at clay loadings below 3 wt%.