INVESTIGATING THE EFFECT OF WATER ON THE POROSITY OF POLYMER FILM FORCONTROLLED DRUG-DELIVERY

This paper describes the effects of water on the properties of ethylce llulose films. The change of density, morphology, porosity, and drug t ransport properties of ethylcellulose films with the water contents in the polymer solutions were investigated. Due to the strong-hydrogen-b onding property of water, the process of dissolving and mixing of ethy lcellulose in a solvent (ethanol) was dramatically changed when a nons olvent (water) was added in this system. Since the solubility paramete r difference between water and-the rest of components, and the evapora ting rate difference between ethanol and water could caused the phase separation of polymer solution during the film-forming process, the po rosity of ethylcellulose films increased with water content in the pol ymer solutions. The film density and the drug permeability of ethylcel lulose films were found to decrease and increase with water content in the polymer solutions, respectively; and these results are very consi stent with the porosity increase of ethylcellulose films.