Polymer surfactant complex

Whereas the charge continuously decreases with increasing SDS content, the surface tension has a minimum near the 1 1 charge ratio. Such complexes were used for the separation of silver particles on zeolite. The separation of such fine particles was impossible with commercial flocculants, but successful with PCSs. 

PSCs can be also used as flocculants in montmorrilonite dispersions [128]. An anionic surfactant (SDS) was combined with a cationic polymer (PDADMAC). At a 1 1 molar ratio, optimal flocculation was obtained owing to the formation of an insoluble surfactant-polymer complex in the presence of particles. Such interactions may lead to a flocculation mechanism that combines polymer adsorption, charge neutralization, and hydrophobic interactions. Other experiments have shown that a similar flocculation process can be achieved by using a cationic surfactant and anionic polymer [127]. 

Hannah et al. [32] have shown that this type of anionic-cationic complex, formed from 0.1% polymer JR and 1% SDS does indeed sorb to the hair. Water can remove only some 30% of this JR-SDS complex, and SDS and salts are no more effective, leaving some 60% (approximately 0.1 mg complex per gram hair) strongly bound to the hair. Analogous complexes with other cationic polymers have been used for binding or for increasing the substantivity of ingredients to the hair [3,4]. 

Polyethyleneimine (PEI) was used commercially in the 1960s and shortly thereafter removed from hair products. However, because of new and improved synthetic techniques, it may be making a comeback. Furthermore, several interesting scientific studies have been conducted with this polymer. They illustrate some useful principles relevant to the adsorption of cationic polymers to keratin fibers. There are two signihcant structural differences between PEI and polymer JR  

Polyethyleneimine is formed from the aziridine ethyleneimine, and its chemistry has been reviewed by Woodard [42]. 

Although PEI is not quaternized, it is highly cationic because a large number of its amine groups are protonated even near neutral pH. Woodard [42] indicates that at pH 10.5, 4% of the amine nitrogens are protonated at pH 8,25% and at pH 4,50%. Therefore, PEI would have a charge density of approximately 176 at pH 8, or nearly four times the frequency of cationic sites as polymer JR. 

Three different polyethyleneimrnes have been described with regard to their interactions with human hair PEI-6 (MW 600) PEI-600 (MW 60,000) and PEI-600E, which is PEI-600 reacted with an almost equivalent amount of ethylene oxide. This reaction with ethylene oxide forms quaternary nitrogen groups and increases the molecular weight to approximately 100,000 [28,42]. 

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On the basis of the above experimental results, the expected conformations of polymer-surfactant complexes at the oil-water interface are depicted in Fig. 2.19. In case I, the added polymer associates with excess surfactants present in the bulk solution, but the complexes prefer to remain in the bulk phase. Alternately, the polymer-surfactant complexes are unable to displace the adsorbed surfactant molecules from the liquid-liquid interface. Irrespective of the amount of polymer-surfactant concentration in the bulk, the experimental decay length values remain comparable to the Debye lengths, corresponding to the concentration of ion species in the bulk solution (Eq. (2.11)). This means that the force profile is... 

Figure 2.19. Schematic diagram of polymer-surfactant complex on emulsions droplets for cases I, II, and III. (Adapted from [74,75].)...

C. Stubenrauch, P.A. Albouy, R. Kitzling, and D. Langevin Polymer/Surfactant Complexes at the Water/Air Interface A Surface Tension and X-Ray Reflectivity Study. Langmuir 16, 3206 (2000). 

Fig. 23 Schematic representation of the formation of polymer surfactant complexes for the pyrene-labeled (polyacrylic acid)-dodecyltrimethylammonium bromide system for high (high pH) and low (low pH) degrees of ionization...

Recent investigations have shown that the behavior and interactions of surfactants in a polyvinyl acetate latex are quite different and complex compared to that in a polystyrene latex (1, 2). Surfactant adsorption at the fairly polar vinyl acetate latex surface is generally weak (3,4) and at times shows a complex adsorption isotherm (2). Earlier work (5,6) has also shown that anionic surfactants adsorb on polyvinyl acetate, then slowly penetrate into the particle leading to the formation of a poly-electroyte type solubilized polymer-surfactant complex. Such a solubilization process is generally accompanied by an increase in viscosity. The first objective of this work is to better under-stand the effects of type and structure of surfactants on the solubilization phenomena in vinyl acetate and vinyl acetate-butyl acrylate copolymer latexes. 

Deposition of Polyquaternium-7 and Polyquaternium-10 from anionic shampoos has been reported to be greatly decreased as a result of the formation of negatively charged polymer/surfactant complexes that are repulsed by negatively charged keratin surfaces [152,157], As was stated earlier, however, these association complexes are still resistant to removal from hair [51]. 

Higher-molecular-weight glycols are believed to form true polymer-surfactant complexes in which the glycol is in the form of a random coil bound to the surfactant with its hydrophilic groups oriented toward the aqueous phase. Here the dye is solubilized in the POE-rich region (Tokiwa, 1973b). 

SDS-l-pentanol-PEO and water-toluene-SDS-l-pentanol-PEO systems and they found an increasing droplet size as a function of the polymer content. Controversial discussions followed [59,60]. If the elastic moduli were the only affected magnitudes one would argue With increasing bending rigidity ( case 1 ) the fluctuations would be diminished, and the radius would decrease due to the opposite surface-to-volume effects. The opposite trends would support case 2 . However, the size could also be changed by polymer incorporation inside the surfactant layer or by polymer-surfactant complexes inside the water domains. These effects would influence the droplet size differently. 

Linse P., Piculell L., Hansson P., Models of polymer—surfactant complexation. In Kwak J. C., ed. Polymer—Surfactant Systems. Surfactant Science Series 77. New York Marcel Dekker, 1998 193-238. 

Water-soluble conjugated polyelectrolytes interact with oppositely charged surfactants forming polymer-surfactant complexes. The polymer urfactant interaction induces changes in the conformation [22[ and optical properties [22-24] of the pol3nner including narrowed absorption and enhanced fluorescence quantum efficiency. In addition, the fluorescence quenching efficiency of... 

The kinetics of 2,4-dinitrophenyl-acetate hydrolysis catalyzed by polymers containing imidazole, carboxylic acid, oxidation groups and their complexes with surfactants, such as 1-cetylpyridinium chloride and cetylundecyldimethylammonium bromide, was determined by spectrophotometry [57]. Catalytic rate constants of the second-order-rate increase with a rise in the surfactant concentration until they reach a plateau at a polymer/surfactant ratio of 1 6. Anionic surfactant does not accelerate the polymer-catalyzed hydrolysis. The catalytic mechanism of a polymer/surfactant complex enables the penetration of the substrate into a pseudophase of a soluble complex. This leads to an increase of the ester concentration in the neighbourhood of a polymer imidazole fragment and accelerates the process. Such a pseudophase promotes the protonation of imidazole rings. 

Anionic sulfonated polyacrylamide (PAMS) is also found to increase amine flotation of quartz. Although PAMS does not adsorb on the negatively charged quartz and cause no direct activation of amine adsorption, the polymer-surfactant electrostatic interaction can lead to the formation of complexes. This polymer-surfactant complex can reduce the armoring of bubbles and lead to flotation. The anionic polymer can also bridge the adsorbed amine to the amine on the bubble surface and enhance flotation under saturated adsorption conditions. The hydration effect of the polymer may also be responsible for the enhanced flotation in this case. 

The interfacial behaviour of surfactant-polymer mixtures, utilized for example in the stabilization of suspensions, depends on a complex interplay between different pair interactions. Addition of a polymer can either remove surfactant from a surface or enhance its adsorption, and vice versa, depending on the relative stability of the polymer-surfactant complexes in solution and at the interface. 

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