Surfactant cast films

Controlled evaporation of SUVs and MLVs on substrates has been shown to result in the formation of ultrathin films which retained the regular bilayer structure of vesicles [69, 425-427]. These immobilized bilayers, termed as cast multibilayers , cast multibilayers , or ordered cast (ultrathin) films , have provided an alternative to LB films [425-446]. Alkylammonium surfactants with azobenzene (33) and glutamate (34) functionalities have been used, for example, in the preparation of cast-film-forming SUVs. X-ray diffraction... 

Chem. Descrip. Sodium phosphate ethoxylate (3 EO) in hexylene glyool Uses Surfactant, emulsifier for emulsion polymerization color enhanoer in resins, esp. acrylics gloss aid, color enhancer, dispersant, corrosion inhibitor, compatibilizer in paints/coatings Features Good mech. and storage stability produces cast films with antirusting props., exc. clarity, improved resist, to degradation by It. and heat reduced water sensitivity in dried films sodium salt of Dextrol OC-40 APE-free... 

Of notable significance to the discussion of UV-vis studies of PAT solvation is the work of Fraleoni-Morgera et al. [184]. They have found that the addition of a surfactant. Tween 80, can solubilize PHT in water. This process was studied using UV-vis by treating the polymer as its own optical probe. The spectrum of the aqueous polymer microemulsion shows a redshift with respect to the same polymer in THF, and vibronic structure similar to that of a drop cast film of the same. The results reveal that while the polymer is in solution, it is conformationally ordered due in part to the formation of aggregates and the interaction of the side chains with the solvent. 

A little more than a decade ago, Kunitake and coworkers described ordered films of water-insoluble surfactants cast onto solid surfaces from organic solvents or aqueous... 

Similar films can be made by mixing a protein solution with a vesicle dispersion of the surfactant, casting this mixture onto an electrode, and drying it. This technique is preferable because it is easier and faster, provides a known amount of protein in the film, and gave Mb-surfactant films that are slightly better ordered [20], Both techniques give comparable voltammetry. Film structure can be represented as in Figure 4. 

The films discussed in this chapter provide a complanentary set of alternatives for fundamental studies of redox enzymes, and for bioreactor and biosensor development. The layer-by-layer polyion- and nanoparticle-protein films have the best mechanical stability. However, cast polyion and surfactant-protein films are stable for a month when hydrodynamic flow is avoided. The cast polyion and surfactant films are the easiest to use for fundamental spectroscopic studies, which can provide information complementary to voltammetry. The liny amounts of protein (nmol range) in all these films lead to very significant cost and time economies. 

The implications for films cast from mixtures of enantiomers is that diagrams similar to those obtained for phase changes (i.e., melting point, etc.) versus composition for the bulk surfactant may be obtained if a film property is plotted as a function of composition. In the case of enantiomeric mixtures, these monolayer properties should be symmetric about the racemic mixture, and may help to determine whether the associations in the racemic film are homochiral, heterochiral, or ideal. Monolayers cast from non-enantiomeric chiral surfactant mixtures normally will not exhibit this feature. In addition, a systematic study of binary films cast from a mixture of chiral and achiral surfactants may help to determine the limits for chiral discrimination in monolayers doped with an achiral diluent. However, to our knowledge, there has never been any other systematic investigation of the thermodynamic, rheological and mixing properties of chiral monolayers than those reported below from this laboratory. 

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