Molecular self-assembly is a process in which molecules (or parts of molecules) spontaneously form ordered aggregates without guidance or management from an outside source. There are two types of molecular self-assembly, intramolecular self-assembly and intermolecular self-assembly. Most often the term molecular self-assembly refers to intermolecular self-assembly, while the intramolecular analog is more commonly called folding. The notion of self-assembled polymers covers large polymerlike structures formed by reversible or non-reversible aggregation of (effective) monomers or smaller polymers. Self-assembling polymers tend to form under appropriate conditions all sorts of large aggregates such as spherical or cylindrical micelles which may in turn effectively behave as huge polymers.
Systems in which polymerization is believed to take place under condition of chemical equilibrium between the polymers and their respective monomers are termed equilibrium polymers (EP). Examples include liquid sulfur and selenium, giant surfactant micelles, supramolecular aggregates of dyes, dipolar colloids and protein filaments. EP differ from conventional "quenched" or "dead" polymers in that they can break and recombine. This has profound consequences for their rheological behaviour. (It also affects the way they can be investigated in computer simulation.) Hence, giant micelles are often referred to as living polymers (LP) in the surfactant literature. This is potentially confusing since they are distinct from systems that reversibly polymerize stepwise, in the presence of a fixed number of initiators, for wich this term was coined by M. Szwarc 50 years ago.
Self-assembled linear structures like giant cylindrical micelles or discotic molecules in solution stacked in flexible columns are systems reminiscent of polydisperse polymer solutions, ranging from dilute to concentrated solutions as the overall monomer density and/or the chain length increases. These supramolecular polymers have an equilibrium length distribution, the result of a competition between the random breakage of chains and the fusion of chains to generate longer ones. This scission-recombination mechanism is believed to be responsible of some peculiar dynamical properties like the Maxwell fluid rheological character for entangled micelles. Simulations employing simple mesoscopic models provide a powerful approach to test mean-field theories or scaling approaches allow to to rationalize the structural and kinetic properties of these soft matter systems.
More information on equilibrium polymers