| Autor: |
Kilian, H. -G., Lagaly, G., Corti, M., Mallamace, F., Deriu, A., Cavatorta, F., Cabrini, D., Middendorf, H. D. |
| Zdroj: |
Trends in Colloid & Interface Science V; 1991, p461-464, 4p |
| Abstrakt: |
Using small-angle neutron scattering (SANS), we have studied Scoh(Q) patterns from agarose gels as a function of concentration, H/D contrast, and temperature. Four characteristic regions become apparent in logS vs logQ plots as C increases up to ∼0.5 g agarose/g water. In the intermediate Q region (0.005 ⩽ Q ⩽ 0.075 Å−1), we find extended linear segments in log-log plots. The slopes of these, i.e., the exponents D in S(Q) ∞ Q−D, can be related to scaling parameters which reflect both the (limited) fractal structure of such gels and their inherent polydispersity. Comparison of measured SANS curves with computer simulations has also been done for model gels. − To address questions relating to the network dynamics, we have measured quasi-elastic spectra at μeV resolution (IN10 at ILL) for fully H2O-exchanged gels. Most of the lines observed can be separated into a central, slightly broadened peak superimposed on a broad, background-like Lorentzian reflecting mainly water translational modes. The observed behaviour can be related to the current description of the dynamics of polymeric chains in solution and shows a crossover from a Rouse-like behaviour (Q<0.5 Å−1) to a higher Q region where the broadening mainly reflects Brownian motions of local segments, as well as limited diffusion of the water of hydration. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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