0000000000368731
AUTHOR
Giacomo Maisano
Effects of isotopic substitution on the conformational properties of polymeric aqueous solutions
Abstract This work deals with a side-by-side comparison between the PEO conformational properties in H 2 O and D 2 O. The gyration radius, evaluated by SANS, the hydrodynamic radius, evaluated by PCS, and the Raman D-LAM band analysis furnish valuable information on the structural arrangement of the molecules. The findings clearly show different behavioural properties of the polymer in H 2 O and D 2 O.
Correlation spectroscopy in molten and supercooled antimony trichloride.
Correlation spectroscopy measurements performed on molten and supercooled antimony trichloride with the homodyne technique show correlation functions that have a nonexponential behavior. Two well-defined distributions of correlation times can be observed in different temporal regions. This behavior is discussed in terms of a structural relaxation of clusters dynamically formed by intermolecular and interchain bonds. The Arrhenius plot of these correlation times shows a linear behavior with the same activation energy for both. In contrast, the activation energy of shear viscosity has a different value, showing that the processes determining the temperature behavior of \ensuremath{\tau} and $…
Quasi-elastic light scattering in polymer-containing microemulsion
Abstract Quasi-elastic light scattering (QELS) was performed in dilute water in oil microemulsion stabilized by AOT surfactant. The water-soluble polyethylene oxide (PEO) with low molecular weight (8000) added to the microemulsion seems to be confined within the aqueous microphase, since PEO is insoluble in oil (n-heptane). The measurements by QELS of diffusion coefficient, at dilute concentrations, allow determination of the size of the droplets. The phase diagram of the microemulsion undergoes remarkable changes on addition of the polymer. The results show that at fixed R ( water surfactant ratio) the droplets decrease their size as the concentration of polymer increases. This occurrence …