The phase behavior of long hydrophobic A−B type silicone surfactants, Me3SiO−(Me2SiO) m - 2−Me2SiCH2CH2CH2−O−(CH2CH2O) n H (Si m C3EO n ), in water and water + octamethylcyclotetrasiloxane (D4) was investigated by studying phase behavior and small-angle X-ray scattering. Si25C3EO15.8 forms a reverse micellar cubic phase (I2) in water and water + D4 systems. This cubic phase is highly thermally stable in a surfactant−water binary system. The thermal stability decreases monotonically with addition of silicone oil. Although the solubilization of water in the reverse cubic phase is low, a very large amount of excess water can be incorporated in a so-called reverse cubic phase based concentrated emulsion. The emulsion stability is enhanced upon addition of silicone oil. D4 molecules penetrate into the surfactant palisade layer in the reverse micelles forming the I2 phase and expand the effective cross-sectional area per surfactant, a S (penetration). The continuous penetration of oil destabilizes the I2 phase structure, and therefore the melting temperature of the phase decreases. The incorporation of D4 into the I2 phase in the aqueous mixtures of Si14C3EO7.8, Si25C3EO7.8, Si25C3EO12.2, and Si25C3EO15.8 varies with both the hydrophilic and lipophilic chain lengths of silicone surfactants.

The authors reviewed the correlations of power consumption in unbaffled and baffled agitated vessels with several kinds of impellers, which were developed in a wide range of Reynolds numbers from laminar to turbulent flow regions. The power correlations were based on Kamei and Hiraoka's expressions for paddle and pitched paddle impellers. The calculated correlation values agreed well with experimental ones, and the correlations will be developed the other types of impellers.

The A−B-type silicone copolymer, Me3SiO−(Me2SiO)23−Me2SiCH2CH2CH2−O−(CH2CH2O)51.6H (Si25C3EO51.6), forms only lamellar liquid crystal (Lα) in water over a whole range of concentrations. Rich phase behavior was observed upon addition of conventional nonionic surfactant, C12EO5, whose molecular weight is ∼1/10 of Si25C3EO51.6. For both amphiphiles, f, the volume fraction of hydrophilic part in amphiphile, is the same, and f = 0.5. C12EO5 alone forms aqueous micellar solution (Wm), normal hexagonal (H1), bicontinuous cubic (V1), lamellar (Lα), and reverse micellar solution (Om) phases in water with increasing surfactant concentration. On the other hand, Wm, discontinuous micellar cubic (I1), Lα, reverse bicontinuous cubic (V2), and reverse hexagonal (H2) phases are successively formed in water at a 70/30 weight ratio of Si25C3EO51.6/C12EO5. A reduction in the effective cross-sectional area per amphiphile at hydrophobic surface (a S) takes place upon addition of C12EO5 in the mixed system. A small amphiphile, C12EO5, is dissolved in the copolymer Lα phase, and a relatively small amount of surfactant occupies a rather large area at an interface of aggregates, although the a S for Si25C3EO51.6 in the Lα phase is more than double that for C12EO5. Hence, the surfactant mainly dictates the morphology or amphiphile-layer curvature in the mixed system. The copolymer is practically insoluble in the Lα phase of C12EO5 due to the packing constraint. Hence, two Lα phases coexist in a surfactant-rich region at W S = 0.75, where W S is the weight fraction of total amphiphile in the system. On the other hand, the copolymer Lα phase changes to the I1 phase with increasing the surfactant mixing fraction at W S = 0.55. The spherical micelle in the I1 phase has a double-layer structure in which the surface is covered by surfactant and the core is pure poly(dimethylsiloxane) chain.

Linear, long poly(oxyethylene) poly(dimethylsiloxane) surfactants, formula Me 3 SiO-form reverse micelles in oil such as poly(dimethylsiloxane) and hydrocarbons. The critical micellar concentration (CMC) decreases dramatically with increasing the hydrophilicchain length of the surfactant, whereas the difference in hydrophobic chain length has less influence on the CMC. Hence, the segregation of the poly(oxyethylene) (EO) chain from nonpolar medium is a main factor to form aggregates in oil. Since the lipophilic surfactants used in this study have very long hydrophilic and hydrophobic chains compared to conventional nonionic surfactants, they also form liquid crystals in nonpolar medium such as discontinuous reverse micellar cubic and reverse hexagonal phases at a high surfactant concentration and even in the absence of solvent. Judging from SAXS data, oil penetrates in the palisade layer of surfactant, increasing the preferred negative curvature and relaxing the packing restriction of the hydrophobic chain. Although a normal micellar cubic phase is always changed to a micellar solution upon dilution with water, the present reverse micellar phase coexists with oil in a wide range of composition in the squalane system.