What is diffusion in polymer solutions & gels?

Diffusion in polymer solutions and gels has been studied by various techniques such as gravimetry, membrane permeation, fluorescence and radioactive labeling. These studies have led to a better knowledge on polymer morphology, transport phenomena, polymer melt and controlled release of drugs from polymer carriers.

How do particles facilitate their own diffusion in a polymer gel?

Accordingly, no wonder so many scientists are looking for the physical mechanism explaining how particles facilitate their own diffusion in a polymer gel giving rise to a perfect filter. For instance, recently it has been found that binding-mediated mechanisms can contribute to enhance diffusion of particles in a gel .

How is diffusion through a polymer gel qualitatively different?

We consider a gel composed of N small star-shaped polymers, in a two-dimensional square box of linear length L with periodic boundary conditions. Note that diffusion through a polymer gel is qualitatively different in two and three dimensions because in two dimensions there is no way to go around a linear filament.

What is the diffusion rate of polymers?

Diffusion in polymers is complex and the diffusion rates should lie between those in liquids and in solids. It depends strongly on the concentration and degree of swelling of polymers. Consequently, it remains a challenge to understand, predict and control the diffusion of small and large molecules in polymer systems.

What are the characteristics of particle diffusion in gels?

In addition, other important characteristics of particle diffusion in gels, such as the stiffness of the gel structure and hydrodynamic interactions, can be taken into account through coarse-grained simulations.

Can a universal equation describe solute diffusion in concentrated polymer solutions?

These models cannot be employed to describe solute diffusion in concentrated polymer solutions. The universal equation proposed by Phillies is a useful equation (simple form, good correlation with experimental data) to fit diffusion data of both small-sized diffusants and macromolecules in all concentration regimes, excepted for melt-like region.