Systematic investigation of functional core variation within hyperbranched polyglycerols

A novel series of hyperbranched polyether polyols with various n-alkyl amine cores (mono- and bifunctional) and photoactive cores (benzylamine and 1-naphthylmethylamine) have been prepared. Polymerization of glycidol was carried out in two ways, starting directly from primary amine initiators and from bisglycidolized amine initiators. NMR spectroscopy and size exclusion chromatography (SEC) showed good control over the molecular weights only, when bisglycidolized amines were used. Molecular weights and polydispersity of the hyperbranched polyglycerols prepared with these initiator-cores were in the range of 1600 to 8400 g/mol and of 1.5 to 2.5, respectively. MALDI-ToF mass spectrometry confirmed covalent attachment of the functional cores to the hyperbranched polymers. When using the bis-glycidolized amine-initiators, only functionally initiated polymers could be observed. In contrast, the direct amine-initiated polymers always showed the presence of nonfunctionalized PIG homopolymer. Steady-state and time-resolved fluorescence measurements further support covalent attachment and site isolation of the functional initiators within the hyperbranched structure. (C) 2008 Wiley Periodicals, Inc.