Single-chain folding of diblock copolymers driven by orthogonal h-donor and acceptor units

We report the precision single-chain folding of narrow dispersity diblock copolymers via pairwise orthogonal multiple hydrogen bonding motifs and single chain selected point folding. Well-defined linear polystyrene (PS) and poly(n-butyl acrylate) (PnBA) carrying complementary recognition units have been synthesized via activators regenerated by electron transfer/atom transfer radical polymerization (ARGET ATRP) utilizing functional initiators yielding molecular weights of M_n,SEC = 10900 Da, ł = 1.09 and M_n,SEC = 3900 Da, ł = 1.10, respectively. The orthogonal hydrogen bonding recognition motifs were incorporated into the polymer chain ends of the respective building blocks (to yield an eight shaped single chain folded polymers). Diblock copolymer formation was achieved via the Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reaction, while the single-chain folding of the prepared linear diblock copolymer-at low concentrations-was driven by orthogonal multiple hydrogen bonds via three-point thymine-diaminopyridine and six-point cyanuric acid-Hamilton wedge self-association. The self-folding process was followed by proton nuclear magnetic resonance (¹H NMR) spectroscopy focused on the respective recognition pairs at low temperature. In addition, the single-chain folding of the diblock copolymer was analyzed by dynamic light scattering (DLS) and concentration dependent diffusion ordered NMR spectroscopy (DOSY) as well as atomic force microscopy (AFM), providing a limiting concentration for self-folding (in dichloromethane at ambient temperature) of close to 10 mg mL^-1.