Phase diagram investigations of symmetric microemulsions of water-n-decane-C10E4-PEP5-PEO5 in the semidilute regime suggested the existence of anisotropic mesophases (C10E4, n-decyl tetraoxyethylene glycol ether; PEP5-PEO5, poly(ethylenepropylene)-co-poly(ethylene oxide), MPEP ) MPEO ) 5 kg mol -1 ). Performing a temperature scan on a sample at fixed composition, we observed an alternating sequence of eight two-phase regions and six one-phase regions. The composition of the sample was chosen to contain equal volumes of water and oil and an overall weight fraction of surfactant and polymer of 0.20. We examined the nature of the lyotropic mesophases and the coexisting phases by measuring the line splitting of 2 H NMR spectra. The experiments unequivocally reveal the existence not only of a lamellar (LR) but also of a normal hexagonal (H1) and a reverse hexagonal (H2) phase.

We present a first time-resolved deuterium NMR study on wormlike micelles under shear. For the investigation, a micellar system made of soybean phosphatidylcholine (lecithin), D2O, and cyclohexane was studied in the concentrated regime, in the vicinity of the isotropic/nematic transition but positioned in the equilibrium isotropic phase. The D2O dispersed in the micellar core was used as a probe to study the relaxation of a shearing-induced nematic phase back to the isotropic liquid state, after cessation of shear. The whole process was followed through time-resolved deuterium spectra and was characterized by a continuous decrease of the measured quadrupolar splitting, proportional to the nematic order parameter

Summary: This paper presents the synthesis of two polymeric surfactants, consisting of a polysiloxane backbone with amphiphilic side chains of the nonionic oligo(ethylene oxide) type, and their phase behavior in aqueous solution, investigated by polarizing microscopy and deuterium NMR spectroscopy using D2O as a probe. Two different side chains, which are isomeric glycerol derivatives, were synthesized and attached to poly(methyl hydrogen siloxane) by a hydrosilylation reaction, resulting in a tail‐type and a mid‐type polysurfactant. The side chains of the tail‐type system are fixed at the end of the hydrophobic moiety, whereas the side‐chains of the mid‐type system are tethered to the polymer backbone by a short spacer close to the hydrophilic‐hydrophobic junction of the amphiphile. Both polymers form a lamellar phase in aqueous solution over a wide range of concentrations, whereas the side chain precursors do not form lyomesophases. The cloud curve and the lamellar region are observed at lower temperatures in the mid‐type polysurfactant.Structures of the isomeric polymers forming lamellar phases.magnified imageStructures of the isomeric polymers forming lamellar phases.

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