Diffusive desorption of small solute molecules from amorphous polymers: poly(methyl methacrylate), poly (vinyl acetate) and poly(n-alkyl 2-cyanoacrylates)
✍ Scribed by W.R. Vezin; A.T. Florence
- Book ID
- 103075343
- Publisher
- Elsevier Science
- Year
- 1981
- Tongue
- English
- Weight
- 579 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0014-3057
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✦ Synopsis
Diffusion coefficients of some aromatic substances in poly(vinyl acetate) and poly(methyl methacrylate) have been measured from desorption rates into aqueous buffers from solid solutions of diffusant in cast polymer films. With ordinary spectrophotometric instrumentation, extension of the measurable range of the diffusion coefficient at infinite dilution to below 10 2~ m 2 sec-' is sometimes possible. Measures values below 10 -~2 m2sec -1 are generally much more quickly obtained, and are apparently at least as reproducible as those obtained by time-lag methods, permitting differential effects of diffusant molecular weight and shape to be studied, with solutes of higher molecular weight than those to which previous published studies were confined. Diffusion coefficients of the same solutes in a number of poly(n-alkyl 2-cyanoacrylates) were measured by desorption from polymer particles and films. The rank order and general dependence of diffusivity upon molecular weight and shape is similar in all three polymers. There is a tendency for the ionic and basic solutes to become bound, probably by covalent linkage, to poly(n-alkyl 2-cyanoacrylate) molecular chain ends.