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Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH

The swelling of polyelectrolyte hydrogels usually depends on the pH, and if the pH is high enough degradation can occur. A microindentation device was developed to dynamically test these processes in whey protein isolate hydrogels at alkaline pH 7–14. At low alkaline pH the shear modulus decreases d...

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Autores principales: Hu, Wei, Martin, Francois, Jeantet, Romain, Chen, Xiao Dong, Mercadé-Prieto, Ruben
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6318615/
https://www.ncbi.nlm.nih.gov/pubmed/30920539
http://dx.doi.org/10.3390/gels3040044
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author Hu, Wei
Martin, Francois
Jeantet, Romain
Chen, Xiao Dong
Mercadé-Prieto, Ruben
author_facet Hu, Wei
Martin, Francois
Jeantet, Romain
Chen, Xiao Dong
Mercadé-Prieto, Ruben
author_sort Hu, Wei
collection PubMed
description The swelling of polyelectrolyte hydrogels usually depends on the pH, and if the pH is high enough degradation can occur. A microindentation device was developed to dynamically test these processes in whey protein isolate hydrogels at alkaline pH 7–14. At low alkaline pH the shear modulus decreases during swelling, consistent with rubber elasticity theory, yet when chemical degradation occurs at pH ≥ 11.5 the modulus decreases quickly and extensively. The apparent modulus was constant with the indentation depth when swelling predominates, but gradients were observed when fast chemical degradation occurs at 0.05–0.1 M NaOH. In addition, these profiles were constant with time when dissolution rates are also constant, the first evidence that a swollen layer with steady state mechanical properties is achieved despite extensive dissolution. At >0.5 M NaOH, we provide mechanical evidence showing that most interactions inside the gels are destroyed, gels were very weak and hardly swell, yet they still dissolve very slowly. Microindentation can provide complementary valuable information to study the degradation of hydrogels.
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spelling pubmed-63186152019-01-17 Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH Hu, Wei Martin, Francois Jeantet, Romain Chen, Xiao Dong Mercadé-Prieto, Ruben Gels Article The swelling of polyelectrolyte hydrogels usually depends on the pH, and if the pH is high enough degradation can occur. A microindentation device was developed to dynamically test these processes in whey protein isolate hydrogels at alkaline pH 7–14. At low alkaline pH the shear modulus decreases during swelling, consistent with rubber elasticity theory, yet when chemical degradation occurs at pH ≥ 11.5 the modulus decreases quickly and extensively. The apparent modulus was constant with the indentation depth when swelling predominates, but gradients were observed when fast chemical degradation occurs at 0.05–0.1 M NaOH. In addition, these profiles were constant with time when dissolution rates are also constant, the first evidence that a swollen layer with steady state mechanical properties is achieved despite extensive dissolution. At >0.5 M NaOH, we provide mechanical evidence showing that most interactions inside the gels are destroyed, gels were very weak and hardly swell, yet they still dissolve very slowly. Microindentation can provide complementary valuable information to study the degradation of hydrogels. MDPI 2017-11-18 /pmc/articles/PMC6318615/ /pubmed/30920539 http://dx.doi.org/10.3390/gels3040044 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Hu, Wei
Martin, Francois
Jeantet, Romain
Chen, Xiao Dong
Mercadé-Prieto, Ruben
Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title_full Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title_fullStr Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title_full_unstemmed Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title_short Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH
title_sort micromechanical characterization of hydrogels undergoing swelling and dissolution at alkaline ph
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6318615/
https://www.ncbi.nlm.nih.gov/pubmed/30920539
http://dx.doi.org/10.3390/gels3040044
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