Small-angle neutron scattering dilute solution

Galant, C. Amiel, C. Wintgens, V. Sebille, B. Ternary complexes with poly(j8-cyclodextrin), cationic surfactant, and polyanion in dilute aqueous solution a viscometric and small-angle neutron scattering study. Langmuir 2002, 18, 9687-9695. 

The Debye function describes the q dependence of scattering data from dilute solutions of ideal chains. Such dilute solutions can either be obtained in a (9-solvent or by having a dilute solution of ordinary chains in a melt of perdeuterated chains. Small-angle neutron scattering data for four dilute concentrations of poly(methyl methacrylate) (PMMA with 2.50 000 g/mol ) in perdeuterated PMMA are shown to be fit by the Debye... 

Even in dilute solutions they associate (49, 50). Published sizes of the micelles vary from 2 to 4 run. Sophisticated analytical techniques such as small-angle X-ray diffraction (SAXS), small-angle neutron scattering (SANS), and NMR were used to study the asphaltene particle or micelle sizes (51). MacKay (15) reported that a MWtof 10,000 g/mol would correspond to a 2 to 4-nm cluster. This is very much smaller than a 1-pm water droplet, and considered to be 1/100 to 1/1000 the droplet diameter. This topic is worthy of a review on its own. However, the colloidal properties of asphaltenes, micelles, and... 

In Table 1 we present the Zp values determined in THF and two different THE/DME mixtures. These values, on the order of 1 rm, are comparable to those reported by Discher and coworkers [38,70] and by Bates and coworkers [71,72] for PEO-PI cylindrical micelles with a core diameter of 20 nm in water. Here PEG denotes poly(ethylene oxide). Bates and coworkers deduced their values of Zp from small-angle neutron scattering experiments, whereas Discher and coworkers determined the Zp values using fluorescence microscopy. The fact that the Zp values that we determined from viscometry are comparable to those of the PEO-PI cyUndrical micelles with similar core diameters again suggests the validity of the YFY theory in treating the nanofiber viscosity data. This study demonstrates that block copolymer nanofibers have dilute solution properties similar to those of semi-flexible polymer chains. 

Most of the methods for determining the molecular weights and sizes of polymers (with the exception of small-angle neutron scattering) require dissolving the polymers in proper solvents first. The measurements are then carried out on dilute solutions. 

The spatial arrangement of the polymer chain is called its conformation. Conformations can be determined in dilute solutions by lightscattering, and in the bulk state by small-angle neutron scattering (SANS). Conformations can also be estimated theoretically from the structure and molecular weight of the polymer. 

Gamez-Corrales R, Berret JF, Walker L, Oberdisse J (1999) Shetir-thickening dilute surfactant solutions the equilibrium structure as studied by small-angle neutron scattering. Langmuir 15 6755-6763... 

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