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Abstract
Spatially non-uniform stresses within thin elastic structures can be used to define a wide variety of buckling modes that provide control over the three-dimensional shapes of materials. By incorporating stimuli-responsive polymer networks within such constructs, it is possible to prepare materials with dynamically reconfigurable shapes and properties. In this regard, light represents an attractive stimulus for actuating shape changes with high resolution in both space and time. While prior efforts to use light as a switching stimulus for driving shape transformations of hydrogels have in large part been hampered by slow photochemical switching kinetics, we have recently studied how photothermal actuation of nanocomposite gels allows for rapid and highly reversible shape changes and motion of gel sheets. Such approaches allow for the precise definition of not only the shape of, but also the interactions between, buckled polymer particles. In particular, we have studied the assembly of multiple shape-controlled hydrogel sheets due to shape-defined capillary interactions.
Bio
Ryan Hayward is a Professor of Polymer Science and Engineering at the University of Massachusetts Amherst. He received degrees in Chemical Engineering from Princeton University (B.S.E, 1999) and the University of California, Santa Barbara (Ph.D., 2004), and was a post-doctoral fellow in Engineering and Applied Sciences at Harvard University from 2004-2005. His group’s research covers a variety of topics in polymers and soft materials, with a focus on thin films and interfaces. Recent areas of interest include swelling-induced deformation of constrained and micro-patterned stimuli-responsive gels, and solution state self-assembly of polymer and particle-based nanostructures. Ryan has received several awards, including the Presidential Early Career Award for Scientists and Engineers (PECASE), the 2013 Journal of Polymer Science Innovation Award, and the 2014 John H. Dillon Medal of the American Physical Society. He serves as an Associate Editor for the journal ACS Macro Letters.