Preparation and properties of stereoregular poly(hydroxyethyl methacrylate) polymers and hydrogels |
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Authors: | D.E. Gregonis G.A. Russell J.D. Andrade A.C. deVisser |
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Affiliation: | Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA;Department of Materials Science, Free University, de Boelelaan 1115, Amsterdam, The Netherlands |
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Abstract: | Linear poly(hydroxyethyl methacrylate) (PHEMA) has been synthesized in highly syndiotactic and highly isotactic configurations. The high syndiotactic PHEMA prepared by u.v. photolysis at ?40° C was found by 13C n.m.r. to have a tactic triad content of 84% syndio, 16% hetero and 0% iso. High isotactic PHEMA was prepared by anionic polymerization of benzoxyethyl methacrylate in toluene followed by selective hydrolysis of the benzoate ester, and was observed by 13C n.m.r. to have a 5% syndio, 15% hetero and 80% isotactic triad content. A linear PHEMA polymer formed by radical polymerization at 60°C in ethanol solvent was found to have a tactic triad content of 58% syndio, 42% hetero and 0% iso. These polymers have been crosslinked with hexamethylene diisocyanate and their water swelling properties determined as functions of temperature and crosslinker concentration. Isotactic PHEMA exhibited greater aqueous swelling below 30° C than the syndiotactic PHEMA samples. The stereochemistry of the polymer chain is shown to be a factor in determining the swelling behaviour of hydrophilic methacrylate gels. |
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