Supramolecular liquid crystallinity as a mechanism of supramolecular polymerization

Two types of supramolecular self-assembling polymers should be distinguished: the open type characterized by units with binding sites exposed to the surface and thus capable of extended growth (e.g. some synthetic and natural supramolecular polymers), and the closed type with binding sites internally compensated yielding well defined oligomeric complexes (e.g. DNA, collagen,haemoglobin). The growth of the open assemblies may be defined as a supramolecular polymerization. Both types form corresponding supramolecular liquid crystalline (SLC) phases, but the behaviour of the closed-type SLC is generally indistinguishable from that of liquid crystals formed by molecularly dispersed units. Quite different is the case of the open-type SLC when the anisotropic forces stabilizing the nematic phase interact with the contact forces that promote the growth of theassembly. In this case a cooperative enhancement of growth occurs simultaneously with the formation of the ordered phase. The theoretical basis for the growth coupled to orientation mechanism, laid down to explain the formation of linear micelle aggregates, may apply to most types of supramolecular polymerization. Outstanding resulting expectations are a large degree of supramolecular polymerization, orientation, superimposition of other growth mechanisms, dampened polydispersity and termination steps.