6533b7d8fe1ef96bd126b567
RESEARCH PRODUCT
Polymer solutions: Equilibrium clusters versus shear clusters
Bernhard A. Wolfsubject
Mesoscopic physicsYield (engineering)Materials sciencePolymers and PlasticsEntropy productionOrganic ChemistryThermodynamics02 engineering and technology010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesGibbs free energyCondensed Matter::Soft Condensed MatterShear (sheet metal)symbols.namesakeVolume fractionMaterials ChemistryCluster (physics)symbols0210 nano-technologyGlass transitiondescription
Abstract Polymer solutions are inhomogeneous on mesoscopic scales as a result of chemical bonds linking their monomeric units. This situation leads to polymer clusters within which the polymer concentration c cluster is only a small fraction of the overall concentration c. The ratio c/ c cluster (overlap parameters Ω ) quantifies the number of clusters that need to overlap to yield c. Equilibrium clusters (minimization of Gibbs energy) and shear clusters (minimization of entropy production) differ fundamentally where Ω equil ≥ Ω shear . Only in the vicinity of the glass transition temperature and at high concentration the opposite is the case. Experimental information on Ω equil as a function of φ, the volume fraction of polymer, yields coil-overlap and cross-over concentrations in agreement with the results of scattering studies; analogous information on Ω shear (φ) gives access to cross-over concentrations under shear. Theoretical aspects and questions of practical interest arising from the observed differences between equilibrium and shear clusters are being discussed.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2021-01-01 | Polymer |