The swelling interface number as a criterion for prediction of diffusional solute release mechanisms in swellable polymers
Article first published online: 8 APR 2003
Copyright © 1983 John Wiley & Sons, Inc.
Journal of Polymer Science: Polymer Physics Edition
Volume 21, Issue 6, pages 983–997, June 1983
How to Cite
Peppas, N. A. and Franson, N. M. (1983), The swelling interface number as a criterion for prediction of diffusional solute release mechanisms in swellable polymers. J. Polym. Sci. Polym. Phys. Ed., 21: 983–997. doi: 10.1002/pol.1983.180210614
- Issue published online: 8 APR 2003
- Article first published online: 8 APR 2003
- Manuscript Accepted: 27 DEC 1982
- Manuscript Received: 18 JUN 1982
When a glassy polymer containing a uniformly dispersed solute is brought in contact with a penetrant, solute diffusion will be associated with the transport mechanism and penetration velocity of the penetrant in the polymer. Analysis and prediction of mechanisms of diffusional solute release may be obtained through a new dimensionless number, the swelling interface number, Sw, which compares the relative mobilities of the penetrant and the solute in the presence of macromolecular relaxations in the polymer. It is shown that a sufficient and necessary criterion for time-independent diffusional solute release rates from these swellable systems is that the Sw be smaller than 10−2. The swelling interface number Sw may be related to easily determined structural and thermodynamic parameters of the solute/polymer/penetrant system. Preliminary experimental results of dynamic water swelling of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) and diffusional release of theophylline from initially glassy copolymers show that decreasing values of Sw are related to increased pseudo-case-II transport kinetics of the solute.