Electrophoretic Mobility of Soft Particles in Concentrated Suspensions

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Polymer Science

Background:

• Electrophoretic mobility is crucial for understanding colloidal particle behavior in suspensions.
• Soft particles, coated with polyelectrolytes, exhibit complex interactions influenced by their structure and the surrounding electrolyte.
• Existing models often simplify particle structure or suspension concentration, limiting applicability.

Purpose of the Study:

• To develop a general theory for the electrophoretic mobility of spherical soft particles in concentrated electrolyte suspensions.
• To investigate the influence of particle volume fraction and polyelectrolyte layer thickness on mobility.
• To provide limiting cases for hard particles and polyelectrolytes.

Main Methods:

• Development of a general theory based on Kuwabara's cell model.
• Analysis of soft particles modeled as hard cores with a polyelectrolyte layer.
• Derivation of approximate analytic expressions for negligible relaxation effects.

Main Results:

• The theory reproduces known results for hard particles (thin layer) and polyelectrolytes (no core).
• For thin polyelectrolyte layers (d<
• For thick polyelectrolyte layers (d>>a), mobility strongly decreases with increasing particle volume fraction.

Conclusions:

• The developed theory provides a comprehensive framework for soft particle electrophoretic mobility in concentrated suspensions.
• The thickness of the polyelectrolyte layer is a critical factor determining the concentration dependence of mobility.
• This work offers insights into the behavior of complex colloidal systems relevant to various applications.