Supramolecular Polymerization

The three major growth mechanisms, namely, isodesmic, ring-chain, and cooperative growth, by which supramolecular polymerizations occur, are reviewed. Supramolecular polymerizations can be classified on the basis of three different principles. These include the physical nature of the noncovalent force that lies at the origin of the reversible interaction, the type of monomer(s) used, and the evolution of the Gibbs free energy of the polymer as a function of conversion. The addition of a second and third dimension will result in additional interaction energies and hence will directly influence the free energy of the self-assembled polymer as the concentration or temperature is changed. Polymerization reactions involving covalent bond formation mostly occur under kinetic control because the potential barrier for the back reaction is often much larger than for the forward reaction. Due to strong kinetic nonlinearities in the growth process and the continuous supply of chemical energy through GTP hydrolysis, these structures exhibit higher level emergent phenomena.