Soft Materials Research

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Hydrogel Mechanics

Our research focuses on the mechanics of stimuli-responsive hydrogels, particularly their constitutive modeling and experimental characterization. We aim to develop predictive frameworks that capture the complex, time-dependent behavior of these materials under various external stimuli. By integrating theoretical modeling with experimental validation, we seek to advance the understanding of hydrogel mechanics for applications in biomedical devices and soft robotics.

Below are the key aspects of our work:

1. Applications of Hydrogels:
   • Utilized in sensors, actuators in microfluidic devices, and drug delivery systems.
2. Research Focus:
   • Development of constitutive equations to describe the mechanical behavior of stimuli-responsive hydrogels.
3. Experimental Techniques:
   • Employed to validate constitutive models and characterize mechanical responses.
4. Interfacial Properties:
   • Investigated on various substrates using developed models.
5. HEMA-DMAEMA Hydrogel:
   • A smart hydrogel exhibiting volumetric changes in response to external stimuli, with primary applications in microfluidic device design.
6. Primary Research Emphasis:
   • Mechanics and behavior of HEMA-DMAEMA under different conditions.

Inter-facial Adhesion

Hydrogels play a crucial role in microfluidic device fabrication and tissue engineering. This research focuses on the swelling behavior and interfacial detachment of HEMA-DMAEMA stimuli-responsive hydrogels on various substrates. Key points include:  The development of constitutive models to describe the swelling-induced stress and mechanical response of these hydrogels.  Experimental techniques to quantify interfacial adhesion and detachment mechanics under varying environmental conditions.

1. Microfluidic Device Applications:
   • Hydrogels aid in fabricating microfluidic devices for genomics, proteomics, and metabolomics.
2. Swelling & Interfacial Behavior:
   • Study of HEMA-DMAEMA hydrogels to understand their adhesion and detachment on different substrates.
3. Tissue Engineering Relevance:
   • Hydrogels serve as an extracellular matrix for cell culture applications.
4. Micro-Patterning Utility:
   • Potential use in structured cell culturing through controlled hydrogel patterning.

Viscoelastic Properties of HEMA-DMAEMA

Stimuli-responsive hydrogels, such as HEMA-DMAEMA, exhibit distinct linear and non-linear viscoelastic properties under varying pH conditions. This study aims to characterize their mechanical response to different buffer environments.

• Investigate viscoelastic behavior of HEMA-DMAEMA hydrogels.
• Analyze both linear and non-linear viscoelastic properties.
• Examine response to different pH buffer solutions.
• Characterize mechanical changes due to environmental stimuli.

Relevant Publications

1. Willis, J. A., Trevino, A., Nguyen, C., Benjamin, C. C., & Yakovlev, V. V. (2023).  Photodynamic Therapy Minimally Affects HEMA-DMAEMA Hydrogel Viscoelasticity. Macromolecular Bioscience, 2300124.
2. Willis, J. A., Trevino, A., Nguyen, C., Benjamin, C. C., Yakovlev, V. V. Photodynamic therapy effects on hydrogel viscoelastic properties. In Photonics in Dermatology and Plastic Surgery 2023 (Vol. 12352, pp. 91-99). SPIE.
3. Karimineghlani, P., Youssef, A. A., & Benjamin, C. C., Energy dissipation in phase change salogels under shear stress. Polymer, 124977 (2022).
4. P.Prabhakaran, C.C.Benjamin (2019). Energy Dissipation in pH-sensitive hydrogels subjected to large amplitude oscillatory shear.  (accepted 10-28-19) Mechanics of Materials.
5. Benjamin, C. C., Lakes, R. S., & Crone, W. C. (2018). Measurement of the stiffening parameter for stimuli-responsive hydrogels. Acta Mechanica, 229(9), 3715-3725.
6. Benjamin CC, Craven RJ, Crone WC, Lakes RS. Viscoelastic characterization of pH-sensitive 2-hydroxyethyl methacrylate (2-dimethylamino) ethyl methacrylate HEMA-DMAEMA hydrogels. Polymer Testing. 2018 Nov 2.
7. Benjamin, C. C., Lakes, R. S., & Crone, W. C. (2017). Viscoelastic Relaxation of HEMA-DMAEMA Responsive Hydrogels. In Experimental and Applied Mechanics, Volume 4(pp. 153-158). Springer, Cham.
8. Benjamin, C. C., Springmann, J. C., Chindhy, S. A., & Crone, W. C. (2014). Experimental Tools for Responsive Hydrogel Characterization. In Fracture and Fatigue, Volume 7 (pp. 7-11). Springer, Cham.
9. Crone, W. C., Chindhy, S., Springmann, J. C., & Benjamin, C. (2013). Experiments on Hydrogels of Varying Shape. In Mechanics of Biological Systems and Materials, Volume 5 (pp. 217-222). Springer, New York, NY.