Cross‐linked lyotropic liquid crystal (LLC) assemblies represent a new class of polymer materials for membrane applications. These materials are formed by the phase‐segregation and self‐assembly of polymerizable amphiphiles in water into condensed ordered ensembles that can be cross‐linked in situ with retention of microstructure. The resulting LLC polymer networks have ordered, nanometer‐scale aqueous and cross‐linked organic domains, which can be used to affect gas solubility and diffusivity through the polymer to help separate molecules via the solution–diffusion mechanism. The open aqueous domains can also be used for pore transport and size exclusion with resolution on the molecular size level. The use and application potential of cross‐linked LLC assemblies as gas separation membranes, selective vapor barrier materials, and water nanofiltration and desalination membranes are presented.
Self-consistent mean-field theory gives an expression for the giant dipole resonance energy which depends on κ (the enhancement of the dipole sum rule by exchange currents). The value of κ needed to fit the GDR is much smaller than that obtained from the integrated photoabsorption cross section, in Suzuki's treatment. A corrected treatment which resolves this discrepancy is given here. 相似文献
A study has been made both of secondary reactions occurring during the reaction of I2 with GeH4, and of the direct reaction between I2 and GeH3I. Both these studies show that the abstraction reaction occurs about 30 times faster than the reaction in the temperature range of 425–446 K. This information is used to show that iodine substitution weakens Ge–H bonds by 14.4 ± 2.5 kJ/mol and that D(H2IGe? H) = 332 ± 10 kJ/mol (79.3 kcal/mol). Possible reasons for the effects of halogen substituents on Ge? H and Si? H bond strengths are discussed. 相似文献
