Counterion-Mediated Hydrogen Bonding Making Poly(styrenesulfonate)-Based Strong Polyelectrolytes pH-Responsive.

Area of Science:

• Materials Science
• Polymer Chemistry
• Physical Chemistry

Background:

• Poly(styrenesulfonate) (PSS) is a strong polyelectrolyte typically exhibiting pH insensitivity.
• This lack of pH responsiveness has limited the use of PSS in advanced smart material applications.
• Understanding the fundamental properties of PSS is crucial for developing novel functional materials.

Purpose of the Study:

• To investigate the pH-responsive behavior of PSS brushes.
• To elucidate the mechanism behind this pH responsiveness.
• To explore the potential of PSS in pH-sensitive smart materials.

Main Methods:

• Utilizing counterion-mediated hydrogen bonding (CMHB) as a mechanism.
• Analyzing the structural changes in PSS brushes at the microscale with decreasing pH.
• Investigating the impact of pH on physicochemical properties like hydration, stiffness, wettability, and adhesion.

Main Results:

• Demonstrated that CMHB induces pH responsiveness in PSS brushes.
• Observed increased hydrogen bonding between hydronium counterions and sulfonate groups as pH decreases.
• Reported a more ordered PSS brush structure and larger sulfonate tilt angles at lower pH.
• Confirmed pH-induced changes in hydration, stiffness, wettability, and adhesion.

Conclusions:

• Established a clear structure-property relationship for pH-responsive PSS brushes.
• Provided new fundamental insights into PSS brush properties.
• Significantly expanded the application potential of PSS-based strong polyelectrolytes in smart materials.