Mapping the phase behavior of coacervate-driven self-assembly in diblock copolyelectrolytes

Area of Science:

• Polymer Science
• Physical Chemistry
• Materials Science

Background:

• Complex coacervation is a phase separation driven by electrostatic attraction between oppositely charged polymers.
• This phenomenon can drive the self-assembly of block copolyelectrolytes.
• Predicting coacervate self-assembly phase behavior is challenging due to numerous parameters and theoretical complexities.

Purpose of the Study:

• To predict the solution-phase assembly of diblock polyelectrolyte pairs using advanced coacervate theory.
• To investigate the influence of molecular design parameters, such as charged block fraction and polymer length, on coacervate self-assembly.
• To explore salt partitioning in microphase-separated block copolyelectrolytes.

Main Methods:

• Utilized recent theoretical advances in coacervate theory.
• Developed predictive models for block copolyelectrolyte self-assembly.
• Generated phase diagrams based on molecular design parameters and environmental conditions (e.g., salt concentration).

Main Results:

• Phase diagrams indicate self-assembly occurs at high polymer and low salt concentrations across various charge block fractions.
• Observed a reentrant transition at high polymer fractions, mimicking self-compatibilized homopolymer coacervate behavior.
• Drew parallels between salt concentration's role in coacervation-driven assembly and temperature's role in chi-driven assembly for intermediate charge block fractions.

Conclusions:

• The study provides theoretical predictions for complex coacervation-driven self-assembly in block copolyelectrolytes.
• Findings align with experimental observations, including reentrant transitions and behavior at high charge block fractions.
• The research offers insights into controlling polymer self-assembly through molecular design and environmental conditions.