Molecular Tracer Diffusion in Nondilute Polymer Solutions: Universal Master Curve and Glass Transition Effects

This is the authors' abstract. We don't add key points for this paper.

Using fluorescence correlation spectroscopy, we investigated the diffusion dynamics of a molecular probe in solutions of polystyrene and polybutadiene with different molar masses ( M w ) and molecular architectures (stars, combs) over a broad concentration range ( c ). Whereas the tracer diffusion coefficient D was found to be insensitive to variations in M w and architecture, the obtained master plot D ( c ) was polymer-specific, reflecting additional friction effects related to the concentration-dependent glass transition temperature T g ( c ). This effect is fully suppressed for the same probe diffusion in poly(dimethylsiloxane) solutions with very low and virtually concentration-independent T g . Hence, a universal master curve of D vs c can be obtained when T g ( c ) is accounted for.