Reduction-cleavable hyperbranched polymers with limited intramolecular cyclization via click chemistry

Abstract

In this contribution, we present new reduction-cleavable hyperbranched disulfide bonds-containing poly(ester triazole)s with limited intramolecular cyclization, which can be synthesized by the Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) of A2 monomer of dipropargyl 3,3′-dithiobispropionate and B3 monomer of tris(hydroxymethyl)ethane tri(4-azidobutanoate). The hyperbranched poly(ester triazole)s possess numerous terminal groups and weight-average molecular weight up to 20,400 g mol−1 with a polydispersity index in the range 1.57–2.17. The CuAAC introduces rigid triazole units into the backbones of hyperbranched poly(ester triazole)s and reduces intramolecular cyclization, which is proved by topological analysis and 1H NMR spectroscopy. The disulfide bonds on backbones endow the reduction-cleavable feature to the hyperbranched poly(ester triazole)s at the presence of dithiothreitol. It gives a novel and convenient methodology for the synthesis of reduction-responsive functional polymer with controlled topologies, and the reduction-cleavable hyperbranched poly(ester triazole)s with limited intramolecular cyclization are expected to possess potential in the application of stimuli-responsive anticancer drug nanocarriers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2374–2380