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Ring-opening polymerization of epoxy end-terminated polyethylene oxide (PEO) as a route to highly crosslinked materials with exceptional swelling behavior. Dianionic glycerol and glycolic acid initiators
R. M. Laine, H-J. Sun, S.G. Kim, J. Rush, M. Mollan, and M. Lodaya
crosslinked polyethylene oxide, highly swellable, drug delivery
Highly swellable polyethylene oxide (PEO) gels were made by anionic ring-opening polymerization of diepoxy-endcapped PEO3400 and PEO8000 using dianionic glycerol and glycolic acid initiators at scales of up to 50 g diepoxide. The glycerol-derived materials swell to almost 20 times their mass in water. The driving force for rapid swelling appears to arise during “crystallization,” as segments between crosslinks are forced to pack under conditions that create high energy domains within the material. Solvation and therefore swelling are driven by the release of the resulting packing energy. These observations may offer insight into methods for designing other highly swellable materials. When the polyfunctional initiators have groups with different reactivities (e.g. alkoxide vs carboxylate), as might be expected, the more nucleophilic functional group appears to dominate the ROP process.
International Polymers J.
2007
56
1006-15
article