Time-Dependent Diffusion Studies on Miglyol Molecules Confined in Permeable Polymeric Capsules

Abstract.

Time-dependent diffusion studies have been done on miglyol molecules confined in ε-caprolactone polymeric capsules prepared by an emulsification–diffusion technique. The nuclear magnetic resonance diffusometry technique implemented in our investigations is the so-called fringe field stimulated echo (FFStE) technique. With FFStE technique, high gradients are available (22 T/m in our experiments) which allow the measurements of the apparent diffusion coefficient for diffusion times between 1 and 300 ms. No internal gradient effects or eddy current effects are to be expected in our measurements. The experimental data have been compared with the theoretical dependence in the short-time limit which allowed us to extract the capsule dimensions. The coincidence with the dimension observed from an electron micrograph is remarkable.