Star-shaped polymers have been prepared by anionic polymerization of ethylene oxide and oxirane derivatives such as allyl glycidyl ether (AGE) onto a bile acid core. Bile acids (BA) are natural amphiphilic compounds that exist in the gastrointestinal tract and help in the digestion of fats by the formation of micellar aggregates. They are used as a core in the preparation of homo- and copolymers bearing chains of poly(ethylene glycol) (PEG), poly(AGE) (PAGE) and its derivatives. BA-PEG polymers can form large micellar aggregates which are capable of solubilizing hydrophobic molecules (drugs), making them interesting systems with potential use as drug delivery vehicles. PEGylated lithocholic acid showed interesting thermoresponsive properties with both lower and upper critical solution temperatures (LCST and UCST). The star-shaped BA-PAGE derivatives exhibit thermosensitive properties in aqueous solutions; and this thermosensitivity can be tuned by the degree of acetylation. The aggregation of these polymers has been studied by light scattering and other techniques. The block copolymers BA-PAGE-PEG manifested an interesting two-step aggregation process. This family of star-shaped polymers provides a useful repertoire of materials with potential biomedical applications.

Thermosensitive star-shaped polymers with a cholane core

243rd National Meeting (2012)

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