Exploring the Long-Term Hydrolytic Behavior of Zwitterionic Polymethacrylates and Polymethacrylamides

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Science

Background:

• Hydrolytic stability is critical for polymers used in aqueous anti-fouling coatings.
• Long-term exposure data for these polymers is scarce.
• Novel polysulfabetaines were investigated for enhanced stability.

Purpose of the Study:

• To evaluate the hydrolytic stability of various polymers used in low-fouling coatings.
• To assess the long-term performance of these polymers in aqueous solutions across different pH levels.
• To determine the suitability of these polymers for anti-fouling applications.

Main Methods:

• Synthesis of nine different polymers, including established and novel polysulfabetaines.
• Storage of polymers in aqueous solutions (PBS, 1 M HCl, pH 10 buffer, 1 M NaOH) for one year.
• Analysis of polymer degradation using proton nuclear magnetic resonance (¹H NMR) spectroscopy.

Main Results:

• Polymers, including polymethacrylates, demonstrated high hydrolytic stability, with no degradation observed in PBS, 1 M HCl, or pH 10 buffer after one year.
• Poly(sulfobetaine methacrylamide) remained stable for one year even in 1 M NaOH.
• Monomers showed varying degrees of hydrolysis, from slow in PBS to very fast in 1 M NaOH.
• A partial lability was observed in the hemisulfate group of polysulfabetaines.

Conclusions:

• The studied polymers exhibit excellent hydrolytic stability, confirming their suitability for anti-fouling applications.
• Steric shielding is proposed as the mechanism for the observed polymer stability.
• While polysulfabetaines show promise, their hemisulfate group requires further consideration for specific applications.