Polymer/surfactant interactions

Abstract

and Summary Polyelectrolytes and oppositely charged surfactants form precipitation complexes which, in many cases, can be completely resolubilized by excess surfactant. In general, maximum precipitation appears to correspond to a single layer of surfactant adsorbed on the polymer, and the resolubilized form to a double layer of surfactant. Prior to formation of the latter, the complexes are highly surface active. An analysis of the solubility diagrams of a cationic hydroxyethyl cellulose derivative, and a homologous series of sodium alkyl sulfates, has provided a value of the adsorption energy, Φ, of these surfactants into the first layer. The value of Φ, viz., 1.1 kT per CH2 group, is somewhat higher than the corresponding value for micelle formation. Studies with a number of surfactants show that polymer/surfactant interaction is most favorable (a) the longer the hydrocarbon chain of the surfactant, (b) the straighter the chain, and (c) when the head group is terminal to the chain. Departures from these conditions reduce the extent of interaction and render difficult resolubilization of the complex. From results on a range of polymers, it is concluded that resolubilization of the precipitated complex is also difficult if the charge density of the polymer is too high.

Interactions between cationic starch and anionic surfactants

“…With the highly substituted CS (DS=0.772), the redissolution is no longer complete. This is also a well-known behaviour of systems redissolving by charge reversal mechanism (Goddard and Hannan, 1977).…”

“…For example, interactions of surfactants with cationised cellulose, has been studied by (Goddard et al, 1976(Goddard et al, , 1977 and nonionic cellulose ethers have been subject of extensive studies by (Piculell, Lindman et al, 1992). The structure of starch is very similar to cellulose, but the difference on the bindings, which link the monoglucose units to form the polymer, makes their chemical behaviour very different.…”

DNA-lipid systems: A physical chemistry study

“…The other two observations mentioned need to be further studied; the observed insolubility may correspond to a quantitative rather than qualitative difference from other polymers and might then be possibly rationalized in terms of the very high linear charge density (18,19), one charge per 1.7 Å (for the double-helix B-form) (14). The salt effect was shown to be complex (11) since the associative phase separation could be both enhanced and decreased depending on the conditions.…”

Interactions between Catanionic Vesicles and Oppositely Charged PolyelectrolytesPhase Behavior and Phase Structure

“…The catanionic system is composed by SDS-DDAB at fixed surfactant mixing ratio of X DDAB ) 0.29. Values for JR400-SDS lines are taken from the work of Goddard et al 43 ( Figure 5); for LM200-SDS lines are from the work by Guillemet et al 31 ( Figure 5). that a much larger surfactant-to-hydrophobe ratio is to be attained for redissolution in the former system.…”