ABSTRACT

Introduction .......................................................................................................... 79

Length Scales of Gels and Emulsions............................................................... 81

Emulsions ...................................................................................................... 82

Gels................................................................................................................. 83

Mass Transport Studies Using a Combination of Microscopy and

NMR Diffusometry.......................................................................................... 85

Diffusion in Heterogeneous Materials...................................................... 86

General Features of Emulsions and Gels................................................. 89

Microstructure-Based Modeling of Water Diffusion .............................. 91

Microstructure ...................................................................................... 91

Calculation of the Propagator............................................................ 92

Comparisons between Microstructure-Based Diffusion

Calculations and NMR Diffusometry .......................................... 93

Probe Diffusion............................................................................................. 95

Acknowledgments ............................................................................................... 97

References ............................................................................................................. 98

Many products are composed of heterogeneous structures of vital

importance to properties such as the diffusion of water and soluble

compounds, release of active compounds, behavior of molecules in complex

structures, consistency, microbial growth, water binding, etc. Yet there is a

lack of knowledge about how to use microstructure design to tailor-make

properties related to water management. One reason is that we know too

little about how a certain complex structure affects the mass transport in

relation to heterogeneity or connectivity over a wide range of length scales.

We also lack techniques for approaching time-dependent structural changes

and interactions between the material and the solvents or solutes.