Abstract
The ability to replicate the load-bearing properties of articular cartilage is attractive for many engineering applications, particularly bearings where low friction, low wear, and high durability are required. Hydrogels are widely used materials spanning many diverse applications owing to their lubricity and unique mechanical/chemical properties. The poor mechanical characteristics of conventional hydrogels, especially their compressive behavior, limit their application in load-bearing applications despite their favorable properties such as poro/viscoelasticity and lubricity. This paper demonstrates a cartilage-inspired approach to produce a structure that benefits from water-swelling resistant and ultrafast recovery behavior of elastomers as well as the stress-relaxation and energy dissipation properties of hydrogels. A method is presented in this work to fabricate interconnected macro-porous elastomers based on sintering poly(methyl methacrylate) beads. The porous elastomer imparted structural support and resilience to its composite with an infused-grafted hydrogel. At 30% strain and depending upon the strain rate, the composite exhibited a load-bearing behavior that was 14-19 times greater than that of pristine hydrogel and approximately 3 times greater than that of the porous elastomer. The equilibrium elastic modulus of the composite was 452 kPa at a strain range of 10%-30%, which was close to the values reported for the modulus of cartilage tested with similar experimental parameters defined in this study. The dissipated energy for the composite at strain rates of 1 and 10-3 s-1 was enhanced by 25-, 25-, 5-, and 15-fold as compared to that for the pristine hydrogel and the porous elastomer, respectively. The cyclic loading tests at two strain rates showed that the composite immediately recovers its load-bearing properties with the maximum load recovery staying above 95% of its initial values throughout the testing. The permeability of the structures was measured experimentally, and the results showed a decrease of permeability by 3 orders of magnitude following hydrogel grafting.
| Original language | English |
|---|---|
| Pages (from-to) | 2694-2708 |
| Number of pages | 15 |
| Journal | ACS Applied Polymer Materials |
| Volume | 3 |
| Issue number | 5 |
| Early online date | 9 Apr 2021 |
| DOIs | |
| Publication status | Published - 14 May 2021 |
Bibliographical note
Funding Information:This study was funded by the Research Project Grant through the Leverhulme Trust entitled “Bio-inspired functional poro-elastic materials” (RPG-2017-281) and was carried out at the University of Leeds and Imperial College London. The authors express their sincere gratitude to Mr. Stuart Micklethwaite from the School of Chemical and Process Engineering, University of Leeds for the help with cryo-SEM sample preparation and image acquisitions. The authors would like to thank all the project partners whom had kind discussions on the topic and the methodology,
Publisher Copyright:
© 2021 American Chemical Society.
Keywords
- bioinspired hydrogel
- cartilage rehydration
- polyacrylamide gel
- polydimethylsiloxane sponge
- poro-elastic
- stress relaxation
- tough hydrogel composite
ASJC Scopus subject areas
- Process Chemistry and Technology
- Polymers and Plastics
- Organic Chemistry