(403d) Complex Coacervation in Polyelectrolyte Brushes | AIChE

(403d) Complex Coacervation in Polyelectrolyte Brushes


Wang, Z. G., California Institute of Technology
The interfacial properties of polyelectrolyte complex coacervates has led to their use in a wide variety of industries, especially for encapsulation technologies. Only recently have studies focused on the behavior of coacervates near a solid surface. Understanding the underlying physics of coacervates near solid surfaces is essential for their eventual use in several applications, such as wet adhesives or lubrication. In this work, we explore the thermodynamic aspects of polyelectrolyte brushes that undergo complex coacervation. We use self consistent field theory to investigate how brush characteristics and phase behavior are modulated with solution conditions like pH, ionic strength, and the electrostatic properties of the the solid surface. We also study the interaction of two like-charge brushes in confinement to measure the adhesion strength between solid surfaces. We find that complex coacervation of the polyelectrolyte brush with oppositely charged polyelectrolyte in solution collapses the brush, and in confinement, coacervation induces attraction between the two surfaces. The transition from extended to collapsed depends greatly on the initial conformation of the brush before addition of free polyelectrolyte, which is determined by a variety of solution and surface characteristics. Our results can be used to guide design and experiments of polyelectrolyte brush systems that utilize the complex coacervation phase transition.