Swelling and binding effects in a polymeric microfiber model for controlled drug release.

The diffusion of model molecules from water dispersions of ethylenevinyl-N,N-diethylglycinate copolymer microfibers has been studied in different conditions. The influence of pH on diffusion rate has been related to water association and swelling effects following structural transitions induced in the copolymer by the acidic medium, rather than to difference in binding of the diffusing species to the macromolecule.