Free-Standing Temperature-Sensitive Hydrogel-Particle Membranes from Evaporating Drops

ORAL

Abstract

We demonstrate a simple method using evaporating colloidal drops to prepare temperature-sensitive membranes composed of micron-sized colloidal hydrogel particles that are up to a few particle diameters thick. Sessile droplets of hydrogel particle suspension were evaporated on silicon wafers. The radially outward flows that drive the common coffee-ring effect push hydrogel particles towards the drop edge wherein the particles attach to the air-water interface. Most of these microgel particles move radially inward along the interface and coat the drop surface. The particles are then cross-linked, forming a membrane. The resultant thin films exhibit a temperature-responsiveness characteristic of the individual particles, permitting modulation of membrane size, shape, and optical transmission. We understand the optical properties using a Mie scattering model and an assumed membrane structure.

*We acknowledge support from grants PENN-MRSEC DMR11-20901, NASA NNX08AO0G, and DMR-1205463. KBA acknowledges support from grant DMR-1206231.

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Authors

  • Tim Still

    • University of Pennsylvania
    • Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104

  • Peter Yunker

    • School of Physics, Georgia Institute of Technology, Atlanta, GA 30332

  • Kevin Aptowicz

    • Department of Physics, West Chester University, West Chester, PA 19383

  • Kasey Hanson

    • Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104

  • Zoey Davidson

    • Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104

  • Matthew Lohr

    • Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104

  • A.G. Yodh

    • Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104