Polymolecular aggregates

Thus, in these two examples the most stable species in solution is not that found in die crystal. The long lifetimes of the metastable species in solution at low temperatures may indicate that the dissolution process leads initially to polymolecular aggregates in which the intermolecular hydrogen bonds are maintained. 

Micelles are large polymolecular aggregates in solutions. They are thermodynamically stable because of intermolecular interactions. Some... 

NXgeli (1858 and later ) introduces the concept "micelle" for a polymolecular aggregate which has internal crystal structure the solid colloids are "Micellvcrbande", the sols "Micellarlosungen". In contrast to crystals which also have external crystal structure, they form non-stoichiometric compounds with the medium (water). Van Bemmelen (1877 and later ) has confirmed this latter point for many gels by the introduction of adsorption as the explanatory principle (he still speaks of absorption) in this case we therefore find the introduction of boundary surface phenomena. 

When now at the beginning of the twentieth century textbooks on colloid science begin to appear, the standpoint is generally that colloidal solutions are dispersions of polymolecular aggregates. In Freundlich s "Kapillarchemie" emphasis is indeed... 

Such cases have been occasionally reported, but appear to the author to be not established. The polymolecular films of Harkins and Morgan (Proc. Nat. Acad. Set., II, 637 (1925)) were with substances which spread very badly and are almost certainly largely present as aggregates precipitated on the surface, not spread at all Lyons and Rideal, and Schulman and Ridcal (Proc. Roy. Soc. A, 124, 344 (1929) 130, 284 (1931)) described bimolecular films of fatty acids on alkaline solutions, but Adam and Miller (ibid., 142, 401 (1933)) found these to consist of mixtures of collapsed small aggregates, very thick, and monomolecular films. 

According to Cockbain, they proposed that the aggregation results from a polymolecular adsorption of the surfactant on the droplet surface. After the formation of a monolayer with hydrophilic groups oriented toward the aqueous phase, a second layer is built with the hydrophobic part of the molecules oriented toward the aqueous phase. The interactions between these hydrophobic portions would cause the aggregation. 

Molecular recognition processes may be used to induce and control processes between polymolecular assemblies such as organization of, and binding to, molecular layers and membranes [11,40], selective interaction of vesicles with molecular films [41], aggregation and fusion of vesicles bearing complementary recognition groups [42,43], etc. 

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