NM R Determination of the Fractal Geometry of Gels Around the Collapse Transition

Abstract

The increase in the surface to volume ratio at the collapse transition of gels can be exploited to allow for an NMR determination of the fractal dimension of the gel surface in the liquid state where this quantity is hard to measure with other techniques. The measured quantities are the ratio be­tween the spin-lattice and spin-spin relaxation times T₁/T₂ of the liquid component and the ratio of the masses or volumes of the gel before and after the collapse transition. The technique has been used to determine the surface fractal dimen­sion of a blood plasma gel.