title: Synthesis of well-defined graft copolymers by combination of enzymatic polycondensation and "click" chemistry.
abstract: Aliphatic polyesters having pendant azide groups were prepared by enzymatic polycondensation in the presence of lipase from Candida antarctica type B (CAL-B). The grafting reaction to the N(3)-functional polyester was carried out quantitatively at room temperature using copper-catalyzed azide-alkyne cycloaddition (CuAAC, "click" reaction) with monoalkyne-functional poly(ethylene oxide) (alkyne-PEO, M(n) = 750 g/mol). Furthermore, both enzymatic polycondensation and "click" reaction were carried out successfully in sequential one-pot reaction. The graft copolymer was surface-active and self-assembled in water. The graft copolymer had a critical aggregation concentration (cac) of 3 × 10(-2) μM in water determined by surface tension measurements. Above cac, the graft copolymer formed single chains and aggregates having a hydrodynamic radius of ∼75 nm. Furthermore, the surface activity of the polymers at the air-water interface was studied by Langmuir trough measurements. The Langmuir isotherm of the graft polymer showed a pseudoplateau resulting from desorption of PEO chains into the subphase upon compression.
authors.affiliation: Martin Luther University Halle-Wittenberg, Department of Chemistry, D-06099 Halle (Saale), Germany.
authors.forename: Toufik
authors.initials: T
authors.lastname: Naolou
authors.forename: Karsten
authors.initials: K
authors.lastname: Busse
authors.forename: Jörg
authors.initials: J
authors.lastname: Kressler
mesh_terms: D001386:Azides; D005656:Fungal Proteins; D008049:Lipase / Q000378:metabolism*; D011091:Polyesters / Q000138:chemical synthesis*; D011092:Polyethylene Glycols; D011108:Polymers / Q000138:chemical synthesis*; D013499:Surface Properties; D013501:Surface-Active Agents
chemical_list: D001386:Azides; D005656:Fungal Proteins; D011091:Polyesters; D011108:Polymers; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D008049:Lipase; C431349:lipase B, Candida antarctica