Soft Materials Research

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Hydrogel Mechanics

We study the mechanics of stimuli-responsive hydrogels.  Hydrogels are used in many different applications from sensors and actuators in microfluidic devices to drug delivery.  The focus of our research is the development of constitutive equations to describe the mechanics of stimuli-responsive hydrogels and experimental techniques to describe these findings.   We have used these constitutive models to determine interfacial properties on a variety of substrates.   Hydroxy-ethyl methacrylate dimethal-amino ethyl methacrylate (HEMA-DMAEMA) in particular is a smart hydrogel that responds with a volumetric change when introduced to an external stimulus and finds its primary use in microfluidic device design.  Much of the work here has concentrated on the mechanics of this particular hydrogel.

Inter-facial Adhesion

Fundamental research on hydrogels can be used by device designers to aid in the fabrication of microfluidic devices used in scientific fields such as genomics, proteoemics and metabelomics.  We study the swelling and interfacial detachment of HEMA-DMAEMA stimuli-responsive hydrogels on different substrates potentially used in these microfluidic devices.  Hydrogels can be used in tissue engineering applications as an extra-cellular matrix and additionally in micro-patterning applications for the culturing of cells.

Viscoelastic Properties of HEMA-DMAEMA

We explore the linear and non-linear viscoelastic properties of stimuli-responsive hydrogels.  HEMA-DMAEMA are stimuli-responsive hydrogels that exhibit different viscoelastic behavior when exposed to different pH buffer solutions and we characterize this behavior.

Relevant Publications

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.