(17b) Influence of Charge Fraction and Sequence on Polyelectrolyte Solution and Brush Properties

Polyelectrolytes exhibit unique solution properties compared to neutral polymers due to charge repulsion along the backbone that increases chain size and results in viscoelastic behavior even at low polymer concentration. Consequently, polyelectrolytes are extensively used in industrial applications, including as thickeners and rheology modifiers for aqueous coatings and flocculation agents for colloids and wastewater treatment. They also play a fundamental role in biological processes, including intracellular phase separation and joint lubrication. Polyelectrolytes may also be anchored onto surfaces to create brush architectures that offer flexible design parameters for imparting tailored interfacial functionality at the nanoscale. The influence of charge sequence and fraction on polyelectrolyte solution and brush behavior, however, is lacking. Here, we use solid phase peptide synthesis (SPPS) and surface-initiated copper(0) controlled radical polymerization (SI-CuCRP) to produce polymers with controlled sequence and charge fractions. Systematic studies using small-angle X-ray scattering (SAXS) and 3D single molecule tracking reveal that charge fraction and sequence influence polyelectrolyte solution conformation and phase behavior, as well as brush height and transport properties.