Supramolecular Helical Miktoarm Star Polymers

We report a hydrogen-bonded supramolecular miktoarm star polymer containing three distinct helical arms. Our design involves two helical poly(methacrylamide) arms connected by a barbituric acid (Ba) at the center, prepared through the reversible addition-fragmentation chain-transfer polymerization with a bifunctional agent. Together with a telechelic helical poly(isocyanide) end-functionalized with a Hamilton Wedge (HW) that is complementary to Ba, the two components assemble into an AB(2)-type star copolymer. The assembly is driven by the hydrogen bonding between HW and Ba, which is quantified by H-1 NMR titration and isothermal titration calorimetry. Gel-permeation chromatography provides evidence for the formation of the desired miktoann star architecture. This strategy of site-specific functionalization on helical polymers provides a modular approach to preparing nonlinear supramolecular ensembles with topologically diverse building blocks.