title: Polyphosphazene Based Star-Branched and Dendritic Molecular Brushes.
abstract: A new synthetic procedure is described for the preparation of poly(organo)phosphazenes with star-branched and star dendritic molecular brush type structures, thus describing the first time it has been possible to prepare controlled, highly branched architectures for this type of polymer. Furthermore, as a result of the extremely high-arm density generated by the phosphazene repeat unit, the second-generation structures represent quite unique architectures for any type of polymer. Using two relativity straight forward iterative syntheses it is possible to prepare globular highly branched polymers with up to 30 000 functional end groups, while keeping relatively narrow polydispersities (1.2-1.6). Phosphine mediated polymerization of chlorophosphoranimine is first used to prepare three-arm star polymers. Subsequent substitution with diphenylphosphine moieties gives poly(organo)phosphazenes to function as multifunctional macroinitiators for the growth of a second generation of polyphosphazene arms. Macrosubstitution with Jeffamine oligomers gives a series of large, water soluble branched macromolecules with high-arm density and hydrodynamic diameters between 10 and 70 nm.
authors.affiliation: Institute of Polymer Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, ,4040, Linz, Austria.
authors.forename: Helena
authors.initials: H
authors.lastname: Henke
authors.affiliation: Department of Applied Experimental Biophysics, Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, ,4020, Linz, Austria.
authors.forename: Sandra
authors.initials: S
authors.lastname: Posch
authors.affiliation: Institute of Polymer Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, ,4040, Linz, Austria.
authors.forename: Oliver
authors.initials: O
authors.lastname: Brüggemann
authors.affiliation: Institute of Polymer Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, ,4040, Linz, Austria.
authors.forename: Ian
authors.initials: I
authors.lastname: Teasdale
mesh_terms: D050091:Dendrimers / Q000138:chemical synthesis* / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D050091:Dendrimers; D009943:Organophosphorus Compounds; D011108:Polymers; C108974:poly(phosphazene)
keywords: biodegradable polymers; dendritic molecular brushes; macromolecular architectures; polyphosphazenes; star polymers