pH-Dependent Friction of Polyacrylamide Hydrogels
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| Názov: | pH-Dependent Friction of Polyacrylamide Hydrogels |
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| Autori: | Allison L. Chau, Conor D. Pugsley, Madeleine E. Miyamoto, Yongkui Tang, Claus D. Eisenbach, Thomas E. Mates, Craig J. Hawker, Megan T. Valentine, Angela A. Pitenis |
| Zdroj: | Tribology Letters. 71 |
| Informácie o vydavateľovi: | Springer Science and Business Media LLC, 2023. |
| Rok vydania: | 2023 |
| Predmety: | 02 engineering and technology, 0210 nano-technology, 01 natural sciences, 0104 chemical sciences |
| Popis: | Polyacrylamide hydrogels are widely used in biomedical applications due to their tunable mechanical properties and charge neutrality. Our recent tribological investigations of polyacrylamide gels have revealed tunable and pH-dependent friction behavior. To determine the origins of this pH-responsiveness, we prepared polyacrylamide hydrogels with two different initiating chemistries: a reduction–oxidation (redox)-initiated system using ammonium persulfate (APS) and N,N,N′N′-tetramethylethylenediamine (TEMED) and a UV-initiated system with 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). Hydrogel swelling, mechanical properties, and tribological behavior were investigated in response to solution pH (ranging from ≈ 0.34 to 13.5). For polyacrylamide hydrogels in sliding contact with glass hemispherical probes, friction coefficients decreased from µ = 0.07 ± 0.02 to µ = 0.002 ± 0.002 (redox-initiated) and from µ = 0.05 ± 0.03 to µ = 0.003 ± 0.003 (UV-initiated) with increasing solution pH. With hemispherical polytetrafluoroethylene (PTFE) probes, friction coefficients of redox-initiated hydrogels similarly decreased from µ = 0.06 ± 0.01 to µ = 0.002 ± 0.001 with increasing pH. Raman spectroscopy measurements demonstrated hydrolysis and the conversion of amide groups to carboxylic acid in basic conditions. We therefore propose that the mechanism for pH-responsive friction in polyacrylamide hydrogels may be credited to hydrolysis-driven swelling through the conversion of side chain amide groups into carboxylic groups and/or crosslinker degradation. Our results could assist in the rational design of hydrogel-based tribological pairs for biomedical applications from acidic to alkaline conditions. Graphical abstract |
| Druh dokumentu: | Article |
| Jazyk: | English |
| ISSN: | 1573-2711 1023-8883 |
| DOI: | 10.1007/s11249-023-01779-4 |
| Rights: | CC BY |
| Prístupové číslo: | edsair.doi...........947b7c4a1d246edbf839181e9f3bb068 |
| Databáza: | OpenAIRE |
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Nájsť tento článok vo Web of Science | Abstrakt: | Polyacrylamide hydrogels are widely used in biomedical applications due to their tunable mechanical properties and charge neutrality. Our recent tribological investigations of polyacrylamide gels have revealed tunable and pH-dependent friction behavior. To determine the origins of this pH-responsiveness, we prepared polyacrylamide hydrogels with two different initiating chemistries: a reduction–oxidation (redox)-initiated system using ammonium persulfate (APS) and N,N,N′N′-tetramethylethylenediamine (TEMED) and a UV-initiated system with 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). Hydrogel swelling, mechanical properties, and tribological behavior were investigated in response to solution pH (ranging from ≈ 0.34 to 13.5). For polyacrylamide hydrogels in sliding contact with glass hemispherical probes, friction coefficients decreased from µ = 0.07 ± 0.02 to µ = 0.002 ± 0.002 (redox-initiated) and from µ = 0.05 ± 0.03 to µ = 0.003 ± 0.003 (UV-initiated) with increasing solution pH. With hemispherical polytetrafluoroethylene (PTFE) probes, friction coefficients of redox-initiated hydrogels similarly decreased from µ = 0.06 ± 0.01 to µ = 0.002 ± 0.001 with increasing pH. Raman spectroscopy measurements demonstrated hydrolysis and the conversion of amide groups to carboxylic acid in basic conditions. We therefore propose that the mechanism for pH-responsive friction in polyacrylamide hydrogels may be credited to hydrolysis-driven swelling through the conversion of side chain amide groups into carboxylic groups and/or crosslinker degradation. Our results could assist in the rational design of hydrogel-based tribological pairs for biomedical applications from acidic to alkaline conditions. Graphical abstract |
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| ISSN: | 15732711 10238883 |
| DOI: | 10.1007/s11249-023-01779-4 |