J. Sanchez Leal

Ecological properties of alkylglucosides

Abstract The good application properties of the alkylpolyglucosides and the development of economical and efficient production processes have promoted an increasing usage of these surfactants. From the study of two ecological properties, biodegradability and toxicity, the environmental compatibility of these surfactants have been evaluated. Different alkylglucosides have been studied: pure n-alkylglucosides (C 8 C 12 ) and commercial alkylgtutxeides oligomeric mixtures. Total biodegradation was studied on both Ready Biodegradability tests and Simulation tests. Toxicity tests were carried out on both Daphnia magna and luminiscent bacteria ( Photobacteriram phasphoreum ). Results obtained in the study on the ecological properties of alkylpolyglucosides allow to conclude the environmental acceptability of this new class of nonionic surfactants.

Permeability changes of phospholipid vesicles caused by surfactants

The partition coefficient at equilibrium of different surfactants between the aqueous phase and the lipid bilayer of small unilamellar vesicle (SUV) liposome has been determined. The release of the fluorescent agent 5-(6) carboxyfluorescein from the interior of liposomes, induced by a nonionic surfactant octylphenol ethoxylated with 10 units of ethylene oxide (Triton X-100), by two anionic surfactants — sodium dodecyl sulphate and sodium dodecyl ether sulphate — and by an amphoteric surfactant dodecyl betaine was studied at sub-solubilizing concentrations. The following increasing order of the partition coefficients obtained for each surfactant can be observed: Triton X-100 > sodium dodecyl ether sulphate > sodium dodecyl sulphate > dodecyl betaine. There was a strong positive association between coefficient of partition and the ability of the different surfactants to modify the permeability of liposomes. The importance of the presence of ethylene oxide units in the molecular structure of the surfactant in relation to alter the partition coefficient in front of SUV liposomes is indicated.

Monomer-micelle equilibrium in the diffusion of surfactants in binary systems through collagen films

Three different binary systems (two anionic/nonionic and one anionic/amphoteric) were selected to study the behavior of these mixtures in their diffusion through a collagen film and the formation of micelle aggregates in such systems. The inhibition observed in the surfactant diffusion of anionic/nonionic and anionic/amphoteric binary mixtures through a collagen film, in comparison with that of single surfactants, has been related to the behavior of these binary systems in the micellization process. The surfactant flux in these systems is mainly determined by the monomeric species. The modification of the equilibrium monomers-micelle aggregates shown by these surfactant binary systems could be also associated with the reduction of the irritancy power for such binary systems.

Effect of homolog distribution on the toxicity of alcohol ethoxylates

Previous work established a high correlation between the potential environmental toxicity of oxyethylenated nonionic surfactants and the average degree of ethoxylation. For this reason, it was considered of interest to determine whether a narrow- or broad-range homolog distribution of polydisperse commercial alcohol ethoxylates would influence toxicity. Ethoxylated fatty alcohols, both linear and branched, were synthesized with sodium hydroxide or an unconventional calcium-based catalyst. Toxicity tests were run onDaphnia magna and luminescent marine bacteria. Toxicity of ethoxylated alcohols as a function of type of ethoxylate homolog distribution (narrow or broad) and average degree of polyaddition is analogous for both test species. However, narrow-range ethoxylates show lower toxicity values than conventional ethoxylates. Differences in toxicity values between broad- and narrow-range ethoxylates depend on the degree of ethoxylation.

Permeability changes in the phospholipid bilayer caused by nonionic surfactants

Abstract The liposome-nonionic surfactant interaction is investigated through the disrupting effect promoted by these surfactant molecules on unilamellar liposome vesicles (mean vesicle size 100 nm) prepared by reverse-phase evaporation. This interaction leads, at the outset, to modifications in the permeability of vesicles which are monitored by changes in the release of the fluorescent dye 5 (6)-carboxyfluorescein (CF) trapped inside the phospholipid bilayers. The nonionic surfactant tested was octylphenol polyethoxylated with, on average, between 8.5 and 20.0 ethylene oxide units, in the subsolubilizing range of surfactant concentrations. The coefficient of the equilibrium partition of each surfactant between the aqueous phase and the lipid bilayer is investigated. The surfactant that shows the highest value from the partition coefficients obtained is the octylphenol with 9.5 ethylene oxide units. There seems to exist a positive correlation between the partition coefficient of the surfactant and its ability to modify the permeability of liposomes. The importance of the hydrophilic-lipophilic balance (HLB) of each surfactant tested on the modification of partition coefficients versus the liposomes is noted.

The alteration of permeability of small unilamellar liposomes by amphoteric alkylbetaine surfactants

Abstract The partition coefficients have been determined for a series of amphoteric alkyl betaine surfactants (alkyl chain lengths C-10, C-12, and C-14), partitioning between the aqueous phase and the lipid bilayer of small unilamellar vesicle liposomes (SUV) made from egg phosphatidylcholine and phosphatidic acid (9:1 molar ratio). The release of the fluorescent agent 5-(6)carboxyfluorescein, induced by the surfactants, was studied at sub-solubilizing concentrations. The following order of the partition coefficients was obtained for the surfactants: tetradecylbetaine > dodecylbetaine > decylbetaine. There was a strong correlation between the partition coefficient and the ability of the different surfactants to modify the permeability of liposomes.

Transparent gels: study of their formation and assimilation of active ingredients through phase diagrams

Multicomponent gel formulations capable of assimilating, simultaneously, several active ingredients of potential application in the cosmetic field were studied.

Sodium lauryl sulphate/amphoteric surfactant interactions: selective diffusion through a collagen film

Diffusion tests of anionic, amphoteric and mixtures of amphoteric/anionic surfactants have been performed using a collagen film.

Influence of the polar phase in the formulation of cosmetics.

Frequently, the incoporation of the polar phase, as a second step in the formulation of a cosmetic, is considered as a simple dilution process. This work shows the influence of the polar phase on the final formulation, according to its constitution as well as the method of incorporation. Modelling the system through a regular tetrahedron suggests alternative ways to the usual method of incorporation (direct titration with a polar phase with a given composition), based on selective incorporation of the polar ingredients (double titration procedures). Depending on the constitution of the polar phase, it is possible to obtain different kinds of formulations (gel, liquids, …), and, depending on the different possibilities of incorporation of the polar ingredients, identical compositions can be formulated in terms of percentage of their components, but showing different rheological characteristics, allowing an adaptation to the required specific needs of formulation.

Physicochemical Behavior of Hercosett/Anionic Surfactant Dispersion and Application on Untreated Wool to Impart Shrinkproofing

The physicochemical properties of dispersions made with the cationic resin Hercosett 57 and anionic surfactants have been investigated. The influence of the hydrocarbon chain and the anionic groups of surfactants has been investigated to determine the relationship between the components and their interactions. The application of resin surfactant complexes on untreated wool samples to confer shrink resistance has also been investigated.