Surface mechanics of polyacrylamide hydrogels following wear
In this work, the changes in elasticity of synthetic hydrogel surfaces following deliberate abrasive surface wear are measured. These polyacrylamide hydrogels – cross-linked polymers consisting of 92% water by mass – undergo surface wear, and their surface elastic properties before and after wear are measured. Quasi-static nanoindentations are performed on the surface using a colloidal probe in an atomic force microscope (AFM), and the elastic modulus is computed from the region of the curves fitting a Hertzian contact regime. The results show that the surfaces are stiffer directly after wear. These changes are recoverable, and after several days of resting underwater, the hydrogel’s surface stiffness characteristics return to similar values as before any wear is applied. From this, it can be deduced that wear removes a soft, swollen surface layer and reveals a stiffer bulk. Surfaces can undergo further wear and re-swell successfully with every repetition of the experiment. This research in surface mechanics of hydrogels after applied surface wear is applicable to load-bearing hydrogel surfaces in the human body.
Polyacrylamide hydrogels, wear, surface mechanics, longitudinal wear, stiffness, regenerating surfaces, AFM, nanoindentation
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign