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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...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2017
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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. |
format | Online Article Text |
id | pubmed-6318615 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
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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