Using laser interference to study the time development of structural inhomogeneities within hydrogels.

Hydrogels are materials composed of inhomogeneously crosslinked polymer chains. When exposed to aqueous solutions, hydrogels can expand up to ten thousand times their dehydrated size. The intense swelling of these materials, along with their inhomogeneous structure, results in varying polymer chain density in hydrated states. The inhomogeneous swelling of hydrogels still requires study. To better understand the time evolution of the polymer chain structure, our team is using two laser interference techniques (Bragg scattering and coherent interference) to develop a three dimensional mapping of polymer chains within hydrogel samples. We have developed a custom experimental apparatus to perform these laser studies, and our preliminary data suggests interesitng applications of the study of these expansion rates. Our goal is to characterize the distinct expansion properties of different hydrogel formulas through their swelling cycles and to create a laser interference lab which can host any number of undergraduate research projects in years to come.