Cyclodextrin-based biodegradable polymer stars: : Synthesis and fluorescence studies

Polymer stars built using aliphatic polyester arms and a β-cyclodextrin (β-CD) core are prepared by two synthetic methodologies. The CD core stars offer the intriguing potential of loading molecules of interest into two zones by exploiting the host–guest chemistry of the hydrophobic CD core and by physical trapping in the polymer arms. Core-first syntheses were achieved through the ring-opening polymerization of rac-lactide, l-lactide, β-butyrolactone and lactide/glycolide monomers generating seven-armed stars with a heptakis(2,6-di-O-methyl)-β-CD core. Arm-first syntheses were achieved through the copper-catalyzed azide-alkyne cycloaddition of alkyne-terminated poly(lactic acid)s, poly(3-hydroxybutyrate) and a heptakis-azido-β-CD. For both synthetic strategies, use of the industry standard catalyst, Sn(Oct)2, gave polymers with broadened dispersities (1·3–1·7) when compared to aluminum complexes supported by salen ligands (