Raman scattering and water structure in nonionic amphiphile solutions.
The structure of water in aqueous solutions of polyoxyethylene nonionic amphiphiles ${\mathrm{C}}_{10}$${\mathrm{E}}_{5}$, where ${\mathrm{E}}_{5}$ denotes ${\mathrm{H}}_{21}$(${\mathrm{OCH}}_{2}$${\mathrm{CH}}_{2}$${)}_{5}$OH, is studied by Raman scattering along an isothermal path crossing the isotropic one-phase region from 0 to 1 amphiphile volume fraction \ensuremath{\varphi}. The isotropic OH stretching-vibration spectrum points out a water behavior that depends on the amphiphile concentration. The data analysis is performed using the bond-percolation model developed for water. The interpretation of scattering data leads to the following structural picture for the water in the systems: for \ensuremath{\varphi} lower than 0.75, water is partially bound to the oxyethylene groups of the amphiphile; above \ensuremath{\varphi}=0.75 all water present in the system is bound. Analogously to the behavior of water in confined geometries, the structure of bound water presents a local fourfold-coordinated environment.
Formation of amorphous PbCrO4 nanoparticles depending on the quantitative control of interfacial water
By controlling water ratio in the micellar droplets, amorphous nanoparticles can be synthesized in the confined interfacial water, while nanocrystals are produced in the bulk water.
Nonionic surfactant mixtures. I. Phase equilibria in C10E4–H2O and closed‐loop coexistence
A detailed phase diagram for mixtures of the homogeneous nonionic surfactant 3,6,9,12‐tetraoxadocosanol (C10E4) with water is presented. Closed‐loop coexistence is shown to be a prominent feature in this system as well as in three other aqueous mixtures of nonionic surfactant to which it is compared: 3,6,9,12,15‐pentaoxapentacosanol (C10E5), decyldimethylphosphine oxide (C10PO), and dodecyldimethylphosphine oxide (C12PO). The sizes and locations of these curves are discussed in terms of a decorated lattice‐gas model of closed‐loop coexistence. The shape of one loop (C10E4) in the vicinity of its lower critical point is nonclassical; β is found to be 0.36±0.02. Sources of complexity in the diagram for C10E4–water are discussed.