Synthesis, Characterization, and Star Polymer Assembly of Boronic Acid End-Functionalized Polycaprolactone

Boronic acid end functionalized polycaprolactone (PCL) polymers were synthesized by ring opening polymerization using a pinacol boronate ester containing (Bpin) initiator The polymerization provides access to boron terminated polymers (i e Bpin PCL OH) with narrow molecular weight distributions (PDI = 1 09) Postsynthetic manipulation of the polymer s terminal hydroxyl group by copper catalyzed azide alkynecycloaddition chemistry provides a series of bis end functional ized polymers with significant structural diversity at the ter mini Deprotection of the boronate ester end group was accomplished with an acidic solid phase DOWEX resin The boronate ester deprotection methodology does not result in hydrolysis of the polymeric backbone The boronic acid tipped polymers were converted into star polymer assemblies using thermal dehydration and ligand facilitated trimenzation Ther mal dehydration of (HO)(2)B PCL OAc to the corresponding bor oxine based star polymer assembly was inefficient and lead to degradation products Ligand facilitated tnmenzation using either pyridine or 7 azaindole as the Lewis base was efficient and mild (c) 2010 Wiley Periodicals Inc J Polym Sci Part A Polym Chem 48 5767-5774 2010