Static inhomogeneities and dynamic fluctuations of temperature sensitive polymer gels

The static inhomogeneities and dynamic fluctuations in polymer gels have been studied by light scattering as a function of the gel preparation temperature, Tprep, and the cross-link density. The light scattered intensity of polymer gels was decomposed to two parts; the intensities due to the thermal fluctuations, IF, and the frozen inhomogeneities, IC. The analysis employing ensemble ( ) and time averaging ( ) of light scattered intensity disclosed that (the thermal fluctuations) depends neither on the cross-link density nor the temperature of gel preparation, but on the temperature of observation. On the other hand, (the frozen inhomogeneities) is a function of both temperatures at preparation and at observation. This clearly shows that gel is matter with dynamic fluctuations superimposed on the static frozen inhomogeneities. The latter are built-in inhomogeneities due to topological constraints of the gel by cross-linking formation.