Supramolecular polymerizations and main-chain supramolecular polymers

The past few decades have seen a significant growth in the field of supramolecular polymerizations, in which (reversible) noncovalent interactions (e.g., hydrogen bonding, metal-ligand coordination, π-π stacking, etc.) between (macro)monomeric units are utilized to build polymeric assemblies. These polymeric aggregates can exist in an equilibrium state between low and high molecular weight species, which in turn opens the door to a new matrix of properties. For example, such supramolecular polymers are potentially an interesting class of stimuli- or environmentally responsive, "smart" materials. Additionally, the establishment of an equilibrium during the assembly process imparts on the system the ability to "proofread" assemblies and, depending on the nature of the (macro)molecules, can allow efficient access to controlled, well-defined nanostructures. This Perspective will focus on the basic concepts of such supramolecular polymerizations, such as mechanism of assembly growth, and the effects of growth kinetics, phase segregation, and growth on the surface has on the assembly and properties of the resulting supramolecular polymers, highlighting these concepts with selected literature examples.