Polyelectrolyte Complex Coacervation across a Broad Range of Charge Densities

Polyelectrolyte complex coacervates of homologous (co)polyelectrolytes with a near-ideally random distribution of a charged and neutral ethylene oxide comonomer were synthesized. The unique platform provided by these building blocks enabled an investigation of the phase behavior across charge fractions 0.10 <= f <= 1.0. Experimental phase diagrams for f = 0.30-1.0 were obtained from thermogravimetric analysis of complex and supernatant phases and contrasted with molecular dynamics simulations and theoretical scaling laws. At intermediate to high f, a dependence of polymer weight fraction in the salt-free coacervate phase (w(P,c)) of w(P, c) similar to f(0.37 +/- 0.01) was extracted; this trend was in good agreement with accompanying simulation predictions. Below f = 0.50, w(P, c) was found to decrease more dramatically, qualitatively in line with theory and simulations predicting an exponent of 2/3 at f <= 0.25. Preferential salt partitioning to either coacervate or supernatant was found to be dictated by the chemistry of the constituent (co)polyelectrolytes.

Automated summary

Polyelectrolyte complex coacervates were synthesized using homologous (co)polyelectrolytes with a near-ideally random distribution of a charged and neutral ethylene oxide comonomer, allowing for investigation of phase behavior and salt partitioning. Experimental results were in good agreement with simulation predictions, showing consistency in trends and behaviors across different charge fractions.