Water diffusion in hydroxyethyl methacrylate (HEMA)-based hydrogels formed by γ-radiolysis
✍ Scribed by Hill, David J T; Lim, McKenzie C H; Whittaker, Andrew K
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 258 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0959-8103
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✦ Synopsis
Polymer hydrogels based upon methacrylates are used extensively in the pharmaceutical industry, particularly as controlled release drug delivery systems. These materials are generally prepared by chemically initiated polymerization, but this can lead to the presence of unwanted initiator fragments in the polymer matrix. In the present work, initiation of polymerization by girradiation of hydroxyethyl methacrylate, with and without added crosslinkers, has been investigated, and the diffusion coef®cients for water in the resulting polymers have been measured through mass uptake by the polymers. The diffusion of water in poly(hydroxyethyl methacrylate) at 310 K was found to be Fickian, with a diffusion coef®cient of 1.96 AE 0.1 Â 10 11 m 2 s À1 and an equilibrium water content of 58%. NMR imaging analyses con®rmed the adherance to a Fickian model of the diffusion of water into polymer cylinders. The incorporation of small amounts (0.2±0.5 wt%) of added ethyleneglycoldimethacrylate-based crosslinkers was found to have only a small effect on the diffusion coef®cient and the equilibrium water content for the copolymers.