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

: Schönemann, Eric; Laschewsky, Andre; Rosenhahn, Axel

Volltext ()

Polymers. Online resource 10 (2018), Nr.6, Art. 639, 23 S.
ISSN: 2073-4360
Deutsche Forschungsgemeinschaft DFG
LA611/14-1; Neue zwitterionische Polymere für "low-fouling" Oberflächen
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IAP ()
polyzwitterions; stability; polymer degradation; hydrolysis; polysulfobetaine; polysulfabetaine; anti-fouling materials

The hydrolytic stability of polymers to be used for coatings in aqueous environments, e.g. to confer anti-fouling properties, is crucial. However, long-term exposure studies on such polymers are virtually missing. In this context, we synthesized a set of nine polymers that are typically used for low-fouling coatings, comprising the well-established poly(oligoethylene glycol methylether methacrylate), poly(3-(N-2-methacryloylethyl-N,N-dimethyl)¬ammonio¬propanesulfonate) (sulfobetaine methacrylate), and poly(3-(N-3-methacryamidopropyl-N,N-dimethyl)ammonio-propane¬sulfonate) (sulfobetaine methacrylamide) as well as a series of hitherto rarely studied polysulfabetaines, which had been suggested to be particularly hydrolysis-stable. Hydrolysis resistance upon extended storage in aqueous sol ution is followed by 1H NMR at ambient temperature in various pH regimes. Whereas the monomers suffered slow (in PBS) to very fast hydrolysis (in 1 M NaOH), the polymers, including the polymethacrylates, proved to be highly stable. No degradation of the carboxyl ester or amide was observed after 1 year in PBS, 1 M HCl or in sodium carbonate buffer of pH 10. This demonstrates their basic suitability for anti-fouling applications. Poly(sulfobetaine methacrylamide) proved even to be stable for 1 year in 1 M NaOH without any signs of degradation. The stability is ascribed to a steric shielding effect. The hemisulfate group in the polysulfabetaines, however, was found to be partially labile.