Temperature-Sensitive Hydrogel-Particle Films from Evaporating Drops
Tim Still , * Peter J. Yunker , Kasey Hanson , Zoey S. Davidson , Matthew A. Lohr , Kevin B. Aptowicz , and A. G. Yodh
A simple method to prepare temperature-sensitive films composed of micrometer-sized colloidal hydrogel particles using evaporating drops of colloidal suspensions is demonstrated. The films range in thickness from a monolayer to approximately fifty particle diameters depending on initial particle volume fraction. Sessile droplets of hydrogel-particle suspensions are evaporated on silicon wafers. The fi lm is formed from particles spread densely over the air–water interface which then cross-link and are deposited on the surface during the evaporation process. The resultant thin films exhibit a temperature-responsiveness characteristic of the individual particles permitting modulation of size, shape, porosity, and optical transmission.
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