The surface activity of chroman-6 (CR-6) and chroman-6 palmitoyl ester (PCR-6) and the interactions with lipid membranes, using 1,2-dipamitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) monolayers, were determined. 8-Anilino-1-naphthalenesulfonic acid titration indicates that none of these molecules was able to form aggregates in aqueous media. The presence of a palmitoyl chain in PCR-6 increases strongly the surface activity of the parent compound (CR-6), rendering a molecule to form stable monomolecular layers. The interaction of both compounds with DPPC and DOPC, measured at constant area or in a compression isotherm model, follows the same trend. Miscibility studies performed with DPPC/CR-6 or PCR-6 indicate that the energies involved are small. The presence of CR-6 and PCR-6 has a soft influence on the compressibility of the Langmuir mixed films. Differential scanning calorimetry studies indicate that CR-6 and PCR-6 modify the temperature and cooperativity of the transition from gel to liquid crystal process in DPPC vesicles.

Esters of L-ascorbic acid with long-chain fatty acids (E-304) are employed as antioxidants in foods rich in lipids. Although their enzymatic synthesis offers some advantages compared with the current chemical processes, most of the reported methods employ the immobilized lipase from Candida antarctica as biocatalyst and free fatty acids or activated esters as acyl donors. In order to diminish the cost of the process, we have investigated the synthesis of ascorbyl oleate and ascorbyl palmitate esters with the immobilized Thermomyces lanuginosus lipase Lipozyme TL IM-which is significantly less expensive than Novozym 435-and triglycerides as source of fatty acids. Lipozyme TL IM gave rise to a lower yield of 6-O-ascorbyl oleate than Novozym 435 when using triolein (64 vs. 84%) and olive oil (27 vs. 33%) as acyl donors. Both 6-O-ascorbyl oleate and 6-O-ascorbyl palmitate displayed excellent surfactant and antioxidant properties. The Trolox Equivalent Antioxidant Capability values for the oleate and palmitate were 71 and 84%, respectively, of those obtained with L-ascorbic acid; however, both derivatives were able to stabilize soybean oil towards peroxide formation.

Soy oil microemulsions has been optimized for systems made of phosphated oleyl ether 3EO as surfactant, oleic acid, diethyleneglycol monoethyl ether, and water. The soy oil solubilization has been estimated as a function of different ratios between surfactant/oleic acid (5/95, 10/90, 15/85, and 20/80) and water/glycol (4/1, 2/1, 1/1, 1/2, and 1/4). The maximum simultaneous solubilization of soy oil and hydrophilic phase (water plus glycol) in ratios 3/1, 1/1, and 1/3 (besides the 1/0 and 0/1) was considered. In order to display the widest microemulsion area, the better ratios surfactant/oleic acid were 10/90, 15/85, and 20/80 when water and glycol ratios were 1/2 and 1/4. For these systems, the transition between W/O, bicontinuous and O/W microemulsions were followed through electrical conductivity changes.

The influence of surfactant structure on the formation of lamellar liquid crystals with very low surfactant concentration was investigated for systems composed of oleic acid, diethyleneglycol ethyl ether and water. Surfactants belonging to anionic and cationic families were checked: phosphated oleyl ether 3 EO (PO 3 EO), triethanolamine oleate (TEAO) and sodium lauryl ether sulphate (SLES) as anionic surfactants and two alkyl trimethylammonium bromide type (C 12 TAB and C 14 TAB) as cationic surfactants. For each of the surfactants, the appropriate relationships between surfactant, oleic acid and glycol to furnish lamellar liquid crystals when these basic compositions were further diluted with water were established. The appropriate ranges of dilution allowing the liquid crystal formation were also determined. These liquid crystals presented an attractive appearance because of their transparency and high viscosity, although in the beginning of its formation, a short range of less viscous compositions (so called liquid/gel compositions) appears in some cases. Through water dilution, the initial surfactant percentages are noticeably reduced being possible liquid crystals with 2–5 wt% of surfactant.

The influence of the fatty acid structure on the formation of transparent gels with lamellar liquid crystal structure, for systems composed of an anionic surfactant, fatty acid, diethyleneglycol ethyl ether and water, was investigated. The influence of the alkyl chain length, for both saturated and unsaturated fatty acids, was considered. Moreover, for a given alkyl chain length, the influence of polyunsaturation was also considered. The results obtained indicate that with saturated fatty acids, it is not possible to form lamellar liquid crystals with the appearance of transparent gels, and that in the case of unsaturated acids, the influence of the alkyl chain length is more important than the degree of unsaturation.

Lamellar liquid crystal formulation, with very low surfactant content, was optimized for the system made of phosphated oleyl ether 3 mol ethylene oxide as anionic surfactant, oleic acid as hydrophobic ingredient, diethyleneglycol monoethyl ether as cosolvent and water. The appropriate relationships between surfactant, fatty acid and glycol to promote the lamellar liquid crystal structure through further water dilution, were established. The physical appearance of these liquid crystals corresponded to viscous transparent gels. The realms of existence of the gels were stated in terms of minimum–maximum percentage of water incorporated. The main goal of this research was to decrease the surfactant content (in the range of 2–5%) needed to form liquid crystals, when usually high percentages are necessary. The study was completed with the rheological behaviour and structural parameters of some of these transparent gels. The attractive aspect of the samples, the perfect transparency and compactness, as well as the similarity to the lamellar liquid crystal structure of the intercellular lipids in the stratum corneum, permit consideration of such gels as adequate topical formulations both in cosmetics and pharmaceuticals.

Two peptides based on the active SIKVAV sequence were synthesized and hydrophobically modified through attachment of a myristoyl residue to the amino terminal group. A comparative study was carried out on the physicochemical properties of both parent and hydrophobically modified structures. Properties studied were hydrophobicity, surface activity, spreadability on aqueous surfaces, penetration in lipid monolayers, aggregation and haemolytic activity. Results obtained indicate that myristoyl containing peptides form micelles at 10(-6) M concentration, whereas parent peptides start to aggregate at 10(-5) M. All of them are able to spread on aqueous surfaces forming stable monolayers. Concerning their haemolytic activity only one of the sequences promotes a partial lysis of erythrocytes after 30 min incubation at 37 degrees C and 10(-5) M concentration in the media.

The preparation of biocompatible microemulsions of soybean oil in systems made of anionic surfactant, oleic acid, water, and several glycols was considered. The selected glycols were ether derivatives (methyl, ethyl, dimethyl, and diethyl ether) of ethylene glycol and diethylene glycol. The study was performed using pseudoternary phase diagrams in which the three apexes were occupied by soybean oil, a combination of surfactant/oleic acid, and a combination of water/glycol, respectively. The widest regions of microemulsions were obtained for systems containing methyl ether and especially ethyl ether of both ethylene glycol and diethylene glycol. The two latter compounds allowed the preparation of oil-in-water, bicontinuous, and water-in-oil microemulsions with final surfactant contents of 3–4%.

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 (pC(20)), 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.

The necessary conditions were established by which several biocompatible ingredients (phosphated oleyl ether 3 mol ethylene oxide as surfactant, oleic acid as the lipophilic ingredient, and diethylene glycol monoethyl ether and 1,2-propanediol as glycols) were combined to formulate transparent gels through dilution with water. This study was carried out at three constant levels of surfactant concentration (5, 10, and 15%), which determined in each case the appropriate ratios between the other three components to give transparent gels. These ratios were expressed as the global ratios between oleic acid and the two glycols together (ranging from 1∶9to 1∶3), whereas the internal ratios between the glycols moved in each case from 1∶0 to 0∶1. The systems with 5% of initial surfactant and a global ratio between oleic acid and the glycols of 1∶7 appeared to be the most effective for minimizing the final surfactant content. They furnished transparent gels at specified levels of water dilution, resulting in final surfactant concentrations in the range of 2–4%. Microscopic observation of the gels through polarized light showed the typical pattern of a lamellar liquid crystal structure. The mild characteristics of these gels, given their low surfactant content and the harmlessness of the other components, in addition to their attractive transparency and the rheological characteristics of plastic fluids make them suitable for application as topical formulations in the cosmetic or pharmaceutical fields.

One of the essential factors involving the formulation of pearl concentrates is the adequate selection of the surfactant base composition in which the pearliser agent (ethyleneglycol distearate) will crystallize during the cooling stage. To dispose an appropriate surfactant base to maintain these crystals in suspension, implies to have a particular aggregation structure, given by both the composition (nature of the surfactants and mixing ratio of combination between them) and its total surfactant concentration in the aqueous medium. This study has been centred on the optimization of the surfactant base composed by sodium lauryl ether sulfate (SLES) and coconut diethanolamide (CDEA). The changes in viscosity occurring when surfactant concentration increases, associated to the sequence of the different kind of micelle aggregates, allowed to select the most appropriate pearliser suspending phase: a micelle phase disc like in shape. Its parallel orientation to the surface under shear application, reflects the incident light rays back to the surface producing the best pearling effect. The optimized pearl concentrate composition consisted in 20 % of ethyleneglycol distearate, 23 % of the total surfactant mixture [SLES/CDEA] in ratio 20/80, and 57 % of water.

Skin care companies try to find the best way for cutaneous hygiene in defective skin conditions. Novel strategies to ensure extra-mild non-soap surfactant cleansing products should be searched for and designed. Among possible strategies, the control of the physicochemical behaviour of surfactants in solution seems to be a promising approach to minimize their irritant properties. To assess this, we have tested – with 28 healthy volunteers by means of 48-hour patch testing – the irritant capacity of the following solutions: sodium lauryl sulphate (SLS) 1% w/w, disodium cocoyl glutamate (SCG) 1% w/w, sodium PEG-4 lauramide carboxylate (SLC) 1% w/w and the mixtures SLS 1% w/w + SCG 1% w/w and SLS 1% w/w + SLC 1% w/w. The cutaneous responses were evaluated by visual scoring and bioengineering measurements of transepidermal water loss, laser Doppler cutaneous blood flow and skin colour reflectance. The experimental values of all bioengineering end-points and visual scores have shown that the addition of co-surfactants to a constant dose of SLS produces a significant reduction of skin irritation notwithstanding an increase in the total surfactant concentration. The physicochemical studies show that the control of the physicochemical behaviour of surfactants in solution could be a promising approach to develop cleansing products with a less damaging effect on the skin.

Sucrose, maltose, leucrose, maltotriose, and beta-D-dodecylmaltoside fatty acid esters with acyl chains having 12 to 18 carbon atoms were enzymatically synthesized and their surface properties -critical micelle concentration, surface tension in water, and interfacial tension between water and xylene- were evaluated. The synthesized esters present critical micelle concentration (CMC) values in the range 2-250 muM with surface tension values ranging from 24.5 to 36.5 mN/m, and interfacial tension values from 1.0 to 9.4 mN/m depending on the compound. For the same acyl chain, CMC values were in the order maltotriose < leucrose < maltose < sucrose. The longest the fatty acid displays the lowest CMC, showing a decrease of one order of magnitude when the chain length was increased by six carbon atoms. beta-D-dodecylmaltoside monoesters exhibited high efficiency as water-in-oil emulsifiers. All the newly synthesized di- and trisaccharide-based surfactants displayed better surface-active properties and higher solubility compared with similar monosaccharide esters.

The new water-soluble amphiphilic phosphines R-(C6H4)-(OCH2CH2)(n)P(Ph)CH2CH2SO3-Na (R = tert-octyl, (n) over bar = 1.4, 5.1, 11.2; R = n-nonyl, <($<(n)over bar> = 1.6, 5.6, 11.4) and RP(Ph)CH2CH2SO3Na (R = n-octyl, CH3(OCH2CH2)(3)) have been synthesized and characterized by NMR (H-1, C-13, P-31) and ES mass spectroscopy. The respective Pd(II) complexes were prepared by reaction with PdCl2(COD). Water solutions of ligands and Pd(II) complexes exhibit surfactant properties that have been studied by surface tension measurements, The critical micelle concentration (cmc) and the area occupied per molecule absorbed in the air/water interface were determined. These data show that the cmc's of ligands are significantly higher than those of their respective metal complexes. This finding can be understood by considering the metal complex as a pseudo gemini surfactant. The values of area occupied per molecule in the interface show that ligands with a middle polyether chain yielded the metal complexes with the highest metal concentration in the interface.

Enzymatic synthesis of fatty acid esters of di- and trisaccharides is limited by the fact that most biological catalysts are inactivated by the polar solvents (e.g. dimethylsulfoxide, dimethylformamide) where these carbohydrates are soluble. This article reviews the methodologies developed to overcome this limitation, namely those involving control over the reaction medium, the enzyme and the support. We have proposed the use of mixtures of miscible solvents (e.g. dimethylsulfoxide and 2-methyl-2-butanol) as a general strategy to acylate enzymatically hydrophilic substrates. We observed that decreasing the hydrophobicity of the medium (i.e. lowering the percentage of DMSO) the molar ratio sucrose diesters versus sucrose monoesters can be substantially enhanced. The different regioselectivity exhibited by several lipases and proteases makes feasible to synthesise different positional isomers, whose properties may vary considerably. In particular, the lipase from Thermomyces lanuginosus displays a notable selectivity for only one hydroxyl group in the acylation of sucrose, maltose, leucrose and maltotriose, compared with lipase from Candida antarctica. We have examined three immobilisation methods (adsorption on polypropylene, covalent coupling to Eupergit C, and silica-granulation) for sucrose acylation catalysed by T. lanuginosus lipase. The morphology of the support affected significantly the reaction rate and/or the selectivity of the process.

The influence of the gas type, air or nitrogen, and the treatment time in an RF glow discharge treatment on the shrink resistance properties of knitted wool fabric and wetting properties of keratin fibres were studied. Wetting properties were determined by means of contact angle measurements on single keratin fibres. This method allows measuring accurately the influence of the plasma gas type and treatment time on fibre hydrophilicity, and its modification with the time elapsed after plasma treatment. The modification of the surface properties should be taken into account, especially, when a biopolymer after-treatment is applied to achieve wool shrink resistance. Surface chemical changes were studied by means of XPS. Topographical changes in the wool fibre surface were observed by scanning electron microscopy (SEM) and surface damage was evaluated by means of the Herbig sac formation.Both air and nitrogen plasma treatments impart shrink resistance to wool fabric and hydrophilic properties to the keratin fibres. Even short exposure times are found to be enough to decrease drastically the advancing water contact angle and, therefore, to increase the shrink resistance effect. Slight differences were observed between the air and nitrogen plasma treatments. The time elapsed after the plasma treatment promotes an increase of the advancing contact angle and a decrease of chitosan adsorption. The plasma treatments studied here modify chemically the epicuticle but it is not removed.

Wetting properties of a solid surface can change as a consequence of chemical treatment. There is a relationship between the molecular structure of a surface and the macroscopic properties of this surface such as wetting and adhesion. Information on the surface energy of a solid was obtained by calculating polar and dispersion force contributions by means of contact angle determination. The superficial modification undergone by human hair treatments with or without hydrogen peroxide at alkaline pH was studied by means of wetting force measurements. The wetting increase in treated human hair fibers was analyzed following the Hüttinger method using contact angle data, taking into account the acid-base and dispersion components of the total wetting adhesion work. The hydrogen peroxide treatment at alkaline pH leads to a partial removal of hydrocarbon chains and to the formation of ionic groups (cysteic acid residues) on the outer scale cell surface. The latter phenomenon was observed by means of an increase in the acid-base adhesion work versus water wetting liquid at alkaline pH. Copyright 2001 Academic Press.

In this paper, a systematic investigation into the structure-property relationship of long-chain N-alkyl amide 1, O-alkyl ester arginine 2, and N-acyl arginine methyl ester analogues 3 is reported. The surface properties were studied by adsorption isotherm curves. Biological properties such as antimicrobial activity, hemolysis, ocular irritation, aquatic toxicity, and biodegradability are discussed and correlated with some specific parameters of the surfactants. These surfactants constitute a novel class of bio-based materials of low toxicity, excellent surface properties, and a wide antimicrobial activity. They selectively disrupt bacteria membranes at submicellar concentrations, but not erythrocytes or skin cell membranes. The presence of two positive cationic charges enhances the antimicrobial activity. The incorporation of ester functionality accelerates biodegradation, From the data obtained, it was concluded that the hydrophobicity is a negative parameter for the toxicity and biodegradability of these surfactants.

Water soluble benzimidazolone derivatives were synthesized by grafting the 6-deoxy-3-O-methyl-D-glucopyranos-6-yl group on the N-3 nitrogen atom of two benzimidazolone units which are linked by either alkylene (type V) or alkyloxypropylene (type VI) groups. Glucopyranosyl groups increase the water solubility (Sw). However, in type V compounds, Sw is very sensitive to the alkyl chain junction length (Sw = 56 10(-4) to 0.13 10(-4) mol.L-1, from n = 4 to n = 12 carbon atoms), whereas for type VI compounds, Sw remains very high (Sw >0.5 mol.L-1, i.e. > 400 g.L-1) when the alkyl chain length varies from n = 4 to n = 16 carbon atoms. Moreover type VI compounds show both micelle formation with characteristic CMC and lamellar lyotropic liquid crystal, while type V do not. The incorporation of type VI compounds to an ethoxylated nonionic surfactant system increases significantly the HLB temperature. It is also showed that Mg2+ and Sr2+ cations are complexed in CH3CN by both type V and type VI compounds with close complexation constant values.