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Indentation: A simple, nondestructive method for characterizing the mechanical and transport properties of pH-sensitive hydrogels

Published online by Cambridge University Press:  23 November 2011

Yuhang Hu ,
Jin-Oh You ,
Debra T. Auguste ,
Zhigang Suo  and
Joost J. Vlassak
Yuhang Hu
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
Jin-Oh You
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
Debra T. Auguste
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
Zhigang Suo
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
Joost J. Vlassak*
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
*
a)Address all correspondence to this author. e-mail: vlassak@esag.harvard.edu
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Abstract

We use instrumented indentation to characterize the mechanical and transport behavior of a pH-sensitive hydrogel in various aqueous buffer solutions. In the measurement, an indenter is pressed to a fixed depth into a hydrogel disk and the load on the indenter is recorded as a function of time. By analyzing the load–relaxation curve using the theory of poroelasticity, the elastic constants of the hydrogel and the diffusivity of water in the gel can be evaluated. We investigate how the pH and ionic strength of the buffer solution, the hydrogel cross-link density, and the density of functional groups on the polymer backbone affect the properties of the hydrogel. This work demonstrates the utility of indentation techniques in the characterization of pH-sensitive hydrogels.

Keywords

DiffusionElastic properties
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 1: Focus Issue: Instrumented Indentation , 14 January 2012 , pp. 152 - 160
Copyright
Copyright © Materials Research Society 2011

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