Characterization of the Lamellar Phase Aerosol OT/Water System by NMR Diffusion Measurements

Incorporation of substituted acrylamides to the lamellar mesophase of Aerosol OT

“…Qualitatively there is a difference between the central peak in the two cases: when the peak arises from isotropic water is usually narrower, since the microcrystallites always have a certain size. In the present case the peak in the transparent samples is broadened and decreases with time, which suggests that it is associated with microcrystallites that are due to an unrelaxed state [38]. Since both the macroscopic appearance and the texture under optical microscope indicate that these samples are monophasic and consist of only one lamellar phase, it appears that these samples contain some microcrystallites in addition to larger ordered domains.…”

Evolution of a Lamellar Domain Structure for an Equilibrating Lyotropic Liquid Crystal

“…However, small deviations from this apparent global isotropy can be observed using DDCOSY. 32 The results obtained regarding anomalies in the 25 wt % samples may be compared with anomalies found in the study by Coppola et al 13 on a range of AOT/water concentrations. These authors found that the lower concentration samples (∼25 wt %) were much more susceptible to perturbation by agitation than those at high concentration (∼60 AOT %).…”

“…Indeed the lamellar categorization for AOT is known to be problematic, and a number of prior studies indicate that various behaviors (lamellar repeat distance, Raman intensities, conductivity, and water diffusion coefficient) of this phase change anomalously over the concentration range. 1,4,[8][9][10][11][12][13] The characterization of defect and domain structures in lyotropic liquid crystals has long been a source of query and debate. 13,[20][21][22][23] Many microscopic techniques suffer from an inability to characterize samples at the macroscale; for example, transmission electron microscopy (TEM) 24,25 and scanning electron microscopy (SEM) enable site-specific defects to be imaged and a qualitative picture of defect types to be obtained at length scales of 10 nm to 100 µm, but, even at low magnification, only a relatively small area of a sample can be investigated.…”

An NMR and SAXS investigation of DMFC composite recast Nafion membranes containing ceramic fillers

“…The time between 90 • and 180 • rf pulses is τ, γ is the magnetogyric ratio, δ is the duration of the gradient pulses, ∆ is the time between the leading edges of the gradient pulses (time of the diffusion) and D is the self-diffusion coefficient. The diffusion studies were performed on a Home-built NMR spectrometer operating at 16 MHz for protons [14]. The 90 • rf pulse length was 9 s, ∆ and g were held constant to 0.020 s and 0.50 T/m, respectively.…”