Influence of Surfactant-Protein Interaction on the Wall Structure of Microcapsules

Abstract Adsorption from solutions of sodium dodecylbenzene sulfonate (SDBS) and gelatin mixtures, on the dispersed paraffin oil droplets surface has been investigated. The adsorbed amount of SDBS and gelatin was estimated by the concentration determinations in the continuous phase, after the oil droplets were removed by centrifugation. From adsorption data, total adsorbed mass of SDBS and gelatin per unit surface area, adsorbed mass of each component, and moles of adsorbed SDBS per gram of gelatin have been calculated. From the prepared emulsions, containing SDBS, gelatin, and formaldehyde (as a crosslinking agent), microcapsules have been produced by the spray drying method, and stability of microcapsules was observed during six months of storage at room temperature. It was possible to obtain stable microcapsules only when emulsions were prepared with preadsorbed SDBS. It was found that stability of microcapsules depended not only on the amount of SDBS and gelatin adsorbed, but also on the type of molecular interaction. The stable microcapsules were formed when the adsorbed mass of gelatin was greater than that of SDBS i.e., when an ionic mechanism of interaction in the adsorption layer was present. With increasing adsorption of the SDBS molecule, a hydrophobic mechanism of interaction appears, which changes the conformational properties of gelatin molecules and reduces the stability of microcapsules.