F. Comelles

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.

Structure-Activity Relationships for Sorption of Alkyl Trimethyl Ammonium Compounds on Activated Sludge

Abstract Association of quaternary ammonium based surfactants with activated sludge from wastewater treatment plants has been studied. Adsorption isotherms on activated sludge particles and surface properties of a series of alkyl trimethyl ammonium compounds have been investigated. The effect of alkyl chain length and the water hardness in those physical-chemical properties have been evaluated. Adsorption on sludge increased with increasing the alkyl chain length in the cationic surfactant molecule. Linear relationships between critical micelle concentration (-log CMC) and efficiency of adsorption at the liquid/gas interface (pC20), and the number of carbon atoms in the alkyl chain length were found for the alkyl trimethyl ammonium compounds. Water hardness decreased the CMC values of the tested alkyl trimethyl ammonium homologues and the extent of their sorption to activated sludge. Langmuir and Freundlich adsorption isotherms described satisfactorily the equilibrium adsorption of the cationic surfactants on activated sludge.

Applications of ternary systems in specific cosmetic formulations

The study of ternary systems leads to the understanding of the physico‐chemical aspect and allows the contribution of the different components to a cosmetic formulation to be developed.

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.

Use of microemulsions as vehicles for nucleophilic reagents in cosmetic formulations

The modifications of chemical reactivity induced in the human hair during its treatment with oxidative (H2O2) or reductive (HSO3Na) agents via a micellar or a microemulsion system have been investigated. For this purpose, phase diagrams of micellar solutions and microcmulsions with H2O2 or NaSO3H have been made in order to find out the corresponding areas of solubility. The properties of conductivity, surface tension and light scattering of various monophasic compositions as a function of their water content, have been studied.

BUTYL LACTATE: A USEFUL COSURFACTANT TO PREPARE O/W MICROEMULSIONS WITH SDS

ABSTRACT The possibility of substitution of the conventional pentanol as cosurfactant by butyl lactate, on the preparation of OAV microemulsions in a system with SDS as anionic surfactant, is investigated. Whereas a narrow region of OAV microemulsion is described for the system with pentanol for a critical ratio 85/15 between water and SDS, butyl lactate leads to wider regions of solubility for different water/surfactant proportions, making easy the preparation of these microemulsions. Besides this advantage, being butyl lactate obtained from renewable resources and considered as a safe and biodegradable product, the microemulsions prepared with this cosurfactant could be applied in technological fields as cosmetic and dermopharmaceutical, where the biological agressivity of pentanol could avoid any practical application. As a complementary study, the influence that 1,3-buryleneglycol as polar cosolvent exert on the microemulsion regions, was also considered. Although according to experimental data given ...

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.

Transparent formulations of a liposoluble sunscreen agent in an aqueous medium.

Transparent formulations of a liposoluble sunscreen in an aqueous medium were studied, taking into account the different chemicals of a selected system situated in the vertices of a regular tetrahedron: sunscreen agent, co‐solvent, (surfactants ± mineral oil) mixture (in the tetrahedron base) and water as the fourth component. Several compositions were selected at optimized component ratios after which water was added progressively. Clear gel and liquid compositions were obtained yielding a sunscreen agent that it suitable for conventional use. The physico‐chemical properties of some compositions were assessed in terms of water/sunscreen agent content.

Selective incorporation of the polar ingredients on the formulation of clear gels through phase diagrams

This paper attempts to systematize the preparation of cosmetic formulations by means of phase diagrams. The general criteria used to adapt the usually complex cosmetic systems to simple ternary diagrams W/O/S, consists of grouping the different ingredients according to their functional characteristics (hydrophilics, lipophilics and amphiphilics) that are located respectively in the corresponding vertices W, O and S. Thus, the polar ingredients are always incorporated simultaneously as a single phase, over the initial combinations O/S according to the classical titration procedure. Selective incorporation of the polar ingredients by means of the so‐called double‐titration procedures was studied. Independent consideration of the polar ingredients leads to modelling of the system in a regular tetrahedron in which the components are located at the four vertices. Several possibilities of double‐titration procedures are considered in the tetrahedron depending on the different sequences of incorporating the polar ingredients. The results obtained show a critical influence of the double‐titration procedures on two main aspects: limits of existence of the transparent gel realms, and rheological behaviour of some selected compositions. The different possibilities compared with the fixed characteristics obtained by the conventional method of preparation constitute an advantage in adapting a final formulation to the specific needs.

Surfactants in Wool Chlorination

The aim of this work has been to undertake a systematic study of wool chemical reactivity against sodium hypochlorite solutions at different pH levels in the absence and presence of surfactant solutions. The degradative effect on wool fibers of the oxidative treatments has been considered in terms of the cysteic acid formed as a consequence of cystine residue rupture. In addition, the adsorption of the surfactant by the fibers during the chlorination treatments has been determined, in an attempt to correlate both parameters (cysteic acid and surfactant adsorption) in order to op timize the process.