Didier ROUX - Academia.edu (original) (raw)

Papers by Didier ROUX

Zeitschrift für Physikalische Chemie, 1996

Journal de Physique Lettres, 1984

Re~u le 25 juin 1984, accepte le leI' aout 1984) Résumé. 2014 Le diagramme de phases composition-... more Re~u le 25 juin 1984, accepte le leI' aout 1984) Résumé. 2014 Le diagramme de phases composition-température du système AOT-eau-décane présente une ligne de points critiques. Nous avons examiné le comportement critique de ce système en fonction de deux paramètres qui contrôlent les interactions entre gouttelettes E/H, à savoir la température et le rapport eau sur savon. Le comportement critique est étudié à l'aide de la diffusion de la lumière. Nos résultats indiquent un comportement de type liquide-gaz. Ils sont en bon accord avec les théories du groupe de renormalisation pour les phénomènes critiques. Abstract. 2014 The phase diagram composition-temperature of the AOT-water-decane system presents a line of critical points. This line has been approached along two paths which control the interactions between W/O droplets. The two parameters investigated are the temperature and the water over surfactant ratio. The critical behaviour has been followed by using light scattering. The data indicate a liquid-gas type behaviour and are in good agreement with the renormalization group theories for critical phenomena.

Micellar Solutions and Microemulsions, 1990

Some general features of field variables and critical phenomena in multicomponent systems are dis... more Some general features of field variables and critical phenomena in multicomponent systems are discussed. Critical behavior of surfactants in solution is specially examined, and results for a ternary system composed with pentanol, water, and sodium dodecyl sulfate (SDS) are presented. The study of the phase diagram leads us to evidence of a critical point and an associated field-like variable. The critical behavior is studied using the temperature (path I) and the field variable (path II) as variables. In both cases, an Ising-like behavior is found.

Europhysics Letters (EPL), 1989

Physical Review Letters, 2001

Http Www Theses Fr, 2000

BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

L'Économie, le Travail, l'Entreprise

Novel active principle carriers containing non-ionic surfactants are disclosed. The surfactants m... more Novel active principle carriers containing non-ionic surfactants are disclosed. The surfactants mainly consist of sucrose and fatty acid esters and form onion-structured microcapsules within which the active material is encapsulated. Compositions suitable for use as food, diet food, cosmetics or pharmaceuticals, containing at least one active material or additive encapsulated in said microcapsules, are also disclosed.

Springer Proceedings in Physics, 1990

Surfactants in solution may associate into two-dimensional aggregates (membranes) which self-orga... more Surfactants in solution may associate into two-dimensional aggregates (membranes) which self-organize either in liquid crystalline phases or, more surprisingly, in a liquid isotropic phase made of connected bilayers. A review of what is known about this phase is presented. Structural and thermodynamical models of the phase are described together with experimental results.

The Journal of Physical Chemistry, 1985

Light scattering and photon correlation spectroscopy have been utilized in studying the effect of... more Light scattering and photon correlation spectroscopy have been utilized in studying the effect of the surfactant chemical nature on micellar interactions in W/O microemulsions. Specifically, the surfactant chemical structure has been altered at the molecular level by adding a ramification near the polar head group. This influence of surfactant structure on micellar interactions has been examined through a series of five homologues of SDS, each variation containing a larger ramification. Analysis of the dispersed phase composition and of the light-scattering data indicates that the amphiphilic surface area occupied per surfactant molecule (including the alcohol contribution) is constant. The increase in the individual surfactant molecule polar head surface area is balanced by a decrease in the alcohol content of the interfacial film. As one proceeds through the SDS series, a definite decrease (from positive to largely negative) has been found for values of second virial coefficients. In terms of attractive potential, this indicates an evolution from hard spheres to largely attractive spheres.

Springer Proceedings in Physics, 1987

The understanding of interactions between membranes has attracted a lot of attention in the last ... more The understanding of interactions between membranes has attracted a lot of attention in the last decade, the reason being the relevance of these interactions in biological processes such as cell-cell interactions. The basic forces between membranes are the van der Waals attraction and the electrostatic repulsion [1]. Besides these two well known forces PARSEGIAN, RAND and coworkers [2] have shown in the last decade that there is another short range interaction between phospholipid bilayers embedded in water. This repulsive interaction is attributed to the hydration of the head groups and decays exponentially with a typical length of 3 A. More recently, HELFRICH [3] has proposed that thermally induced out of plane fluctuations of membranes in a multilayer system can lead to a long range repulsive interaction. The crucial elastic modulus which controls the strength of this interaction is kc associated with the bending energy of a single membrane. For this steric interaction to compete with the microscopic forces (that is, van der Waals and electrostatics), kc has to be of order kBT simply because the interaction is induced by thermal fluctuations. Steric repulsion is also known to be the dominant interaction associated with wandering walls of incommensurate phases [4]. Despite much theoretical [5,6] and experimental [7,8] effort the experimental relevance of this interaction to biological membranes remains controversial.

Journal de Physique, 1985

2014 Nous présentons des résultats obtenus par diffusion de la lumière en différents points d'une... more 2014 Nous présentons des résultats obtenus par diffusion de la lumière en différents points d'une ligne critique d'un système microémulsion quaternaire. Cette ligne débute par un point critique extreme. Les points critiques ont été approchés, soit en faisant varier la température à composition constante (chemin I), soit en faisant varier le rapport eau sur savon (X) à température constante (chemin II). Pour chaque point critique examiné, les valeurs des exposants critiques 03BD et 03B3 mesurées le long des deux chemins sont proches. Elles varient continûment des valeurs d'Ising à des valeurs très petites quand le point critique considéré s'approche du point critique extreme. Ce comportement critique complexe est analysé à l'aide des résultats du diagramme de phase. Abstract 2014 We present light scattering results obtained for a four-component microemulsion system in several distinct positions of a critical line. This line starts at a critical end point The critical points were approached either by raising the temperature at fixed composition (path I) or by increasing the water over surfactant ratio X at constant temperature (path II). For each critical point investigated, the critical exponents 03BD and 03B3 associated with the X variable (path II) are close to those obtained with the temperature (path I). They vary continuously from the Ising values to largely smaller ones as the critical end point is approached. This complex critical behaviour is discussed in relation with the phase diagram findings.

Dynamics of Ordering Processes in Condensed Matter, 1988

The nucleation and growth of “Breath Figures”, the patterns formed when vapor condenses onto a co... more The nucleation and growth of “Breath Figures”, the patterns formed when vapor condenses onto a cold surface, are investigated for water. They have been studied by simultaneous microscopic and light-scattering observations. The parameters of the growth: contact angle θ of the drops with the surface, incident gas flow, degree of supersaturation, have been varied. For θ = 90., the growth of the pattern (after an initial period during which the surface coverage and the droplet polydispersity reach a constant value), is self-similar in time. The radius of an average droplet grows with a power law with exponent np ≃ 0.75, whereas the growth of a single droplet between two coalescences obeys a power law with a lower exponent ns ≃ 0.23. Comparisons are made between the experiments, theory s and numerical simulations.

Physical Review Letters, 1991

pictures View other presentations The Spherulites ® : an innovative encapsulation system for acti... more pictures View other presentations The Spherulites ® : an innovative encapsulation system for active ingredients