title: Aggregation and thermoresponsive properties of new star block copolymers with a cholic acid core.
abstract: Poly(allyl glycidyl ether) (PAGE) and poly(ethylene glycol) (PEG) blocks were sequentially grown via anionic polymerization to form four block copolymer arms on a cholic acid (CA) core, yielding star block copolymers (CA(AGE(8)-b-EG(n))(4)) with low polydispersities (ca. 1.05). The introduction of PAGE segments into CA(PEG)(4) significantly reduced their crystallinity. The polymers can aggregate in water at room temperature above their critical aggregation concentration. The copolymers are thermoresponsive; their behavior in aqueous solutions was studied by the use of UV-visible spectroscopy, dynamic light scattering, and transmission electron microscopy. Their cloud points vary from 13 to 55 °C with increasing length of the PEG segments. Double thermoresponsive behavior was observed with short PEG segments because of a two-step transition process: small micelles are formed upon heating and then further aggregate into micellar clusters through the association of PEG chains.
authors.affiliation: Department of Chemistry, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada.
authors.forename: Cancan
authors.initials: C
authors.lastname: Li
authors.forename: Christine
authors.initials: C
authors.lastname: Lavigueur
authors.forename: X X
authors.initials: XX
authors.lastname: Zhu
mesh_terms: D019826:Cholic Acid / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry*; D008968:Molecular Conformation; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D004852:Epoxy Compounds; D011092:Polyethylene Glycols; D019826:Cholic Acid; C054361:allyl glycidyl ether