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Characterization of Hydrogel Deformation Using Two-Parameter Hyperelastic Models.
Joseph M Scalet1, Faiz Mandani1, Stevin H Gehrke1
1Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA.
Gels (Basel, Switzerland)
|February 26, 2026
Summary
This study compares hyperelastic models for hydrogel deformation, finding Ogden and Rubinstein-Panyukov models better capture material behavior than the standard neo-Hookean model, offering insights into gel network structures.
Area of Science:
- Materials Science
- Polymer Science
- Rheology
Background:
- Hydrogels are widely modeled using the neo-Hookean model, which is accurate only within a limited strain range.
- Understanding hydrogel deformation over broader ranges is crucial for applications and for elucidating network structure.
Purpose of the Study:
- Evaluate hyperelastic models (Mooney-Rivlin, Ogden, Rubinstein-Panyukov, Localization) as alternatives to the neo-Hookean model for poly(ethylene glycol diacrylate) (PEGDA) hydrogels.
- Assess model performance across various precursor molecular weights and synthesis concentrations.
- Gain insights into hydrogel network structures, particularly the role of entanglements.
Main Methods:
- Synthesized PEGDA hydrogels via photopolymerization with varying molecular weights (700-4000 Da) and concentrations (5-30 wt%).
- Applied uniaxial compression tests to the synthesized hydrogels.
- Fitted experimental data to four hyperelastic models and assessed fits using Mooney plots (reduced stress vs. inverse extension ratio).
Main Results:
- The Ogden model provided the best fit to stress-strain curves and Mooney plots across the broadest range of PEGDA formulations.
- Localization and Rubinstein-Panyukov models accurately described low-strain behavior and compression maxima for concentrations above the overlap concentration (c*).
- Model parameters indicated that entanglements significantly influence hydrogel behavior, with their contribution decreasing as network concentration increases.
Conclusions:
- The Ogden, Rubinstein-Panyukov, and Localization models offer superior alternatives to the neo-Hookean model for describing hydrogel deformation.
- Two-parameter models show significant potential for understanding complex hydrogel deformation behavior and network properties.
- Entanglement effects are significant across all tested concentrations, providing key insights into the mechanical response of PEGDA hydrogels.
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