Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Poster Session III

CPP 33.21: Poster

Dienstag, 13. März 2018, 14:00–16:00, Poster C

Entanglement in semiflexible polyelectrolyte solutions — •Carlos Lopez — RWTH Aachen University

We present shear rheology data for solutions of semiflexible polyelectrolyte sodium carboxymethyl cellulose (NaCMC) in salt-free water and aqueous solutions of various electrolytes.

The plateau modulus (G_e), estimated from the crossover between the elastic modulus and loss modulus in oscillatory shear, scales as with concentration G_e ∼ c^1.7. The entanglement concentration is approximately independent of added salt concentration. The data presented here, along with a review of the literature suggests that electrostatics have only a weak effect on entanglements, despite having a large effect on polymer conformation.

The reptation model correctly predicts the variation of solution viscosities with concentration and molecular weight in high salt solution but fails in salt-free solution, where an exponent ≃ × 3 larger than the reptation prediction is observed.

These observations presented here clash with scaling arguments which assume that the entanglement tube diameter is proportional to the correlation length and hence dependent on solvent quality.