Supramolecular Polymers in Aqueous Media

Abstract

This review discusses one-dimensional supramolecular polymers that form in aqueous media. First, naturally occurring supramolecular polymers are described, in particular, amyloid fibrils, actin filaments, and microtubules. Their structural, thermodynamic, kinetic, and nanomechanical properties are highlighted, as well as their importance for the advancement of biologically inspired supramolecular polymer materials. Second, five classes of synthetic supramolecular polymers are described: systems based on (1) hydrogen-bond motifs, (2) large π-conjugated surfaces, (3) host-guest interactions, (4) peptides, and (5) DNA. We focus on recent studies that address key challenges in the field, providing mechanistic understanding, rational polymer design, important functionality, robustness, or unusual thermodynamic and kinetic properties.

Controlling supramolecular polymerization through multicomponent self‐assembly

“…[4][5][6][7][8] Many exciting applications have emerged for supramolecular polymers and supramolecular materials, [9][10][11][12][13] that incorporate mechanical, 14 biological, [15][16][17][18][19] optical, 20 or electronic functionalities. 21,22 Similar to covalent polymers, mechanistic investigations of supramolecular systems have highlighted the need to differentiate between the thermodynamically controlled cooperative nucleation-elongation mechanism, noncooperative isodesmic self-assembly or ringchain equilibria, 8,[23][24][25][26][27][28][29][30] and kinetically controlled self-assembly pathways. 22,[30][31][32][33][34][35][36][37][38][39][40][41][42] However, despite the large advances in elucidating mechanistic details, strategies to rationally manipulate mechanisms and self-assembly pathways in supramolecular polymerization remain scarce.…”

“…21,22 Similar to covalent polymers, mechanistic investigations of supramolecular systems have highlighted the need to differentiate between the thermodynamically controlled cooperative nucleation-elongation mechanism, noncooperative isodesmic self-assembly or ringchain equilibria, 8,[23][24][25][26][27][28][29][30] and kinetically controlled self-assembly pathways. 22,[30][31][32][33][34][35][36][37][38][39][40][41][42] However, despite the large advances in elucidating mechanistic details, strategies to rationally manipulate mechanisms and self-assembly pathways in supramolecular polymerization remain scarce. While it is possible to use the toolbox of supramolecular and physical organic chemistry to tune the affinity of a monomer for itself, via molecular design or via concentration and temperature dependent selfassembly, precise engineering of molecular weight, shape, and size of the produced supramolecular polymer remains challenging.…”

“…Water represents a unique medium for self-assembly [44][45][46] and robust supramolecular systems can only be produced by combining weak noncovalent interactions with hydrophobic shielding. 30,43,[47][48][49] Compared to the extraordinary achievements in precision polymer synthesis via living and controlled covalent polymerization processes, [50][51][52][53][54][55][56][57][58][59] supramolecular chemists have only just learned how to developed strategies that allow similar control over polymer length, sequence and morphology. The discussion in this highlight article is focussed on four strategies that have been developed as promising methodologies to control supramolecular polymerization using two or more building blocks, in order to produce well-defined materials with respect to architecture, size, stability, and stimuliresponsive properties.…”

“…A detailed understanding of the supramolecular polymerization mechanisms has been recognized to be fundamentally important in order to design self-assembled functional nanomaterials. 8,[23][24][25][26][27][28][29][30][120][121][122] Sijbesma and coworkers have shown that bifunctional phosphine (P(Phe) 2 C 12 (Phe) 2 P)-based palladium(II) coordination polymers can be obtained with high molecular weights of 7 3 10 5 g mol 21 , after preparing the polymers in the melt (Fig. 3).…”

“…These could be reduced by the addition of what the authors call a chain terminator, a monofunctional (N-methyl)imidazolyl Znporphyrin. In the light of recent developments in manipulating the kinetic stabilities and kinetic pathways in selfassembled supramolecular complexes [128][129][130][131][132][133][134][135][136] and supramolecular polymers, 22,[30][31][32][33][34][35][36][37][38][39][40][41][42]130,[137][138][139][140][141][142][143][144][145] it is interesting to note, that the addition of the chain stopper to the polymers did not lead to instantaneous disassembly. 127 The expected depolymerization and shortening of the polymers based on the comonomer feed ratio was only observed when the di-and monofunctional comonomers were premixed in a good FIGURE 3 (a) Chemical structures for the bi-and monofunctional phosphine ligands, P(Phe) 2 C 12 (Phe) 2 P and P(Phe) 2 C 12 , in order to prepare palladium(II)-based coordination polymers.…”