Single-Chain Folding of Diblock Copolymers Driven by Orthogonal H-Donor and Acceptor Units

Abstract

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, Đ = 1.09 and M n,SEC = 3900 Da, Đ = 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.

Advances in single chain technology

“…Particular emphasis is placed on dynamic (stimuli-responsive), [19][20][21][22][23] letter-shaped 24,25 and compositionally unsymmetrical single rings. [32][33][34][35][36][37][38][39][40][41][42] Interestingly, some of these complex multi-ring nano-objects can be considered as topological analogues of natural macrocyclic peptides found in various organisms. Illustrative examples are also included in this review.…”

Platinum(II)‐Crosslinked Single‐Chain Nanoparticles: An Approach towards Recyclable Homogeneous Catalysts

“…Following the "repeat unit approach", [26,27] the monomers styrene and 4-(diphenylphosphino)styrene were statistically copolymerized, incorporating the functional units directly into the polymer chain (Figure 1A). Following the "repeat unit approach", [26,27] the monomers styrene and 4-(diphenylphosphino)styrene were statistically copolymerized, incorporating the functional units directly into the polymer chain (Figure 1A).…”

Stepwise Unfolding of Single‐Chain Nanoparticles by Chemically Triggered Gates

“…[1][2][3] Proteins fold dynamically into more complex structures,s uch as a-helices and b-sheets.I ntramolecular hydrogen bonds,a romatic stacking, and hydrophobic interactions typically stabilize the formed architectures. However,n atures exquisite degree of control is beyond the reach of contemporary synthetic macromolecular chemistry.…”

“…[8,28] Thef ormation of the hydrogen bonds of the HW/CA moieties [18] as well as the host-guest interaction is verified in the 1D 1 HNMR spectrum ( Figure 1). [3,34] Changes in the aromatic region at 6.9-7.7 ppm, resonances c and d,a sw ell as the change of the CH 2 resonance e associated with the ethyl-eneoxy bridges of the B21C7 next to the phenol ring at 4.21 ppm indicate the interaction of the B21C7-AS moieties,asthe chemical environment changes due to the host-guest interaction ( Figure 1). [18] Thei mide proton resonances in the range of 11-13 ppm of CA are in ac oalescence regime,w here the resonances of the bound NH protons are very broad, likely due to as trong exchange broadening (see also Figure S35).…”

“…Before the unfolding behavior of P16 was investigated (see Figure 2b), the B21C7-AS motif in P6 was tested to evidence the unfolding abilities of the system in aS CNP context (see Figure 2a). [3,22] TheDLS data indicate atransition from intramolecular folding to the formation of intermolecular aggregates when going to higher concentrations.Starting at ac oncentration of approximately 8mgmL À1 ,i ntermolecular interactions dominate (cf. [3,22] TheDLS data indicate atransition from intramolecular folding to the formation of intermolecular aggregates when going to higher concentrations.Starting at ac oncentration of approximately 8mgmL À1 ,i ntermolecular interactions dominate (cf.…”