Polysoap, natural

Modification of poly(2-vinylpyridine) with a long-chain K-dodecyl bromide was the first published example of a polysoap in the literature [192]. (The term polysoap arises from the fact that the resulting modified polyelectrolyte displays similar properties to that of an ordinary soap [192,193].) Dependent on the aqueous solution conditions and the nature of the hydrophobe, modified polyelectrolytes can associate either intramolecularly or intermolecularly [194], and this has created interest from a technological perspective potential applications include use as associative thickeners and rheology modifiers [195]. 

Although several natural polysoaps have been discovered [79, 80], the vast majority of polysoaps are synthetic polymers. As a basic requirement the polymers must have an appropriate hydrophilic-hydrophobic balance HLB to allow for water solubility on one hand (not just dispersion ), but sufficient hydrophobic parts to enable aggregation on the other. Considering the successful and unsuccessful systems in the literature, it seems that the required HLB for polysoaps is slightly more hydrophilic than for low molecular weight surfactants (see also Sect. 4.2). 

These steric problems with their consequences should affect all vinylic surfactant polymers, independent of the inherent surface curvatures of the different models of polymeric micelles (see Sect. 4.2). Thus, vinylic surfactant homopolymers of other than tail end geometry should be of very limited use as polysoaps. In fact, very few exceptions to the geometry controlled model of solubility have been reported [82, 106, 128, 225, 289-291]. In these examples, the chemical integrity of the polymers prepared, the attributed structures, or the polymeric nature may be questioned considering the results obtained for very similar compounds [115,232,309], But even if these exceptions are real, this rule will help to design new monomers and polymers. 

Basically, two types of solubilization studies can be distinguished. In the first type, solubilization is only a tool to incorporate probe molecules into the polysoaps, to learn of the nature of hydrophobic domains available, e.g. their size, form and polarity etc. ( qualitative solubilization ). The majority of such studies employs dye probes whose spectral properties are sensitive to the environment of the chromophore [20, 362-366]. The second, less frequent type... 

The effects of the polymer geometry and of the nature of the backbone are interdepending. Considering Fig. 29, only a hydrophobic backbone will provide a hydrophobic interior of polymeric micelles for polysoaps of the tail end geometry, whereas only a hydrophilic backbone will provide a favourable polarity profile for polysoaps of the head type . Accordingly, optimized ... 

The problem of emulsification and stabilization of dispersions is still to be addressed. At present, only mostly qualitative statements are available. E.g., good emulsifying properties are implied for the reported use of polysoaps in emulsion polymerization [376] and for the stabilization of latexes [50, 214], Good emulsifying properties are reported as well for natural polysoaps [79, 80], Oligomeric polysoaps are efficient emulsifiers for liquid hydrocarbons [82]. High dispersing efficiency for alumina particles is claimed for some polymerized surfactants [377, 378]. But structure-property relationships are still to be... 

Organic molecules with limited water solubility were solubilized by those poly soaps for which viscosity studies indicated micellar behavior (6). The solubilization had varied effects on the viscosity of the polysoap solutions, depending on the nature of the solubilized compound and the concentration... 

The intrinsic viscosity [q] (ml/g) of the polysoap in the organic phase is given as a function of a in Figure 8. A marked dependence of [ti] on the nature of the ion and opposite to the trend of the thermodynamic constant (which increases in the direction Na>K>Cs, cf. Figure 5) is displayed. Qualitatively, one may say that the occurrence of intramolecular polymer-polymer bonds is greater for the ions the most in need of hydration. 

The interaction between an acidic phospholipid, the natural (wheat) phosphatidylinositolmonophosphate PI and a linear cationic polysoap the poly(2-methyl-5-vinyl-hexylpyridinium bromide) PVPC6 has been studied with mixed spread monolayers and with hydrated (40%, w/w) mixed bilayers. The "electrostatic" interaction between PI and PVPC6 involves monolayer condensation and affects the bilayers hydration. In addition, the free energy of the bilayers structural water is modulated by this interaction. 

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