A remarkable correlation exists between the degree of expansion of polyurethane foams and the structure of the reacting premixes. Polyurethane foams obtained from reacting premixes containing microemulsions are highly expanded. The expansion rate is proportional to the volume fraction of microemulsion in the premix. The stability of premixes with and without microemulsion is completely different suggesting distinct creaming mechanisms. We apply this idea to synthesize polyurethane foams from microemulsions successfully. This approach can be used to rationalize the design of polyurethane formulations leading to highly expanded foams. (c) 2005 Elsevier Ltd. All rights reserved.

Surfactant-containing systems are characterized by the self-assembly of aggregated units that endow the bulk level with emergent physical properties. The aggregates themselves take on different shapes from lamellae to spheres. During the last decade the soft matter complexity in this field has been contributed by the polymeric component. I will focus on the addition of amphiphilic copolymers in structured surfactant phases on simple shapes, i.e., flat bilayers, cylinders and spheres. In all cases, the hydrophobic block of the copolymer adsorbs on the surfactant layer, whereas the hydrophilic tails remain in the aqueous solvent and decorate the film. The guest component modifies both the elastic properties of the film and the interactions between the surfactant mesoscopic objects. Small angle neutron scattering is the main experimental technique we used to reveal and analyse some of these polymer-induced modifications.

Fluorescence recovery after pattern photobleaching is used to measure the self-diffusion of surfactant molecules, along cylinders and perpendicular to their main axis in an oriented hexagonal lyotropic phase. Unexpectedly, while the motion along cylinders is diffusive, a superdiffusive behavior is observed in the direction perpendicular to the cylinder axis. Moreover, varying the lattice parameter, we found that the perpendicular diffusion time is governed only by the number of cylinders to cross, providing experimental evidence for superdiffusion with a bounded step length.

We have developed a detailed numerical method based on the Caille model to fit Small Angle Neutron Scattering profiles of powder-oriented lyotropic lamellar phases. We thus obtain quantitative values for the Caille parameter and the smectic penetration length from which we can derive the smectic compression modulus and the membrane mean bending modulus. Our method, applied to a surfactant lamellar phase system decorated by amphiphilic copolymers, provides excellent fits for any intermembrane spacing or membrane concentration over the entire q-range of the SANS experiments. We compare our fits with those obtained from the model of Nallet et al. (J. Phys. II 3, 487 (1993)), which is reviewed. Good fits are obtained with both methods for samples exhibiting "hard" smectic order (sharp Bragg peak, moderate small angle scattering). Only our procedure, however, gives good fits in the case of "soft" smectic order (smooth Bragg peak, strong small angle scattering). A quantitative criterion to discriminate between these "soft" and "hard" samples is also proposed, based on a simple analogy with smectic-A liquid crystal in contact with an undulating solid surface. This allows us to anticipate the type of thermodynamic information that can be derived from the fits.