Microscopic observation of dynamics and structure in microgel suspensions

ORAL

Abstract

We use 3D confocal microscopy to understand the packing dynamics and structure of fluorescently labeled p(NIPAm-co-AAc) microgel colloidal particles. Such systems respond to changes in temperature, pH, and polymer content by changing size, morphology, and interaction behavior. We conduct experiments to understand this behavior in detail: our results show that the dynamics are dominated by attraction driven crystallization and concentration at low pH and concentration only at high pH. Crystal nucleation occurs homogeneously in the suspensions and does not appear to be restricted to geometric boundaries. The growth of crystals is nucleation-limited and can complete on the order of hours. Structural analysis of the crystals formed indicates that the stacking style is insensitive to charge, concentration, size, and stiffness of the particles and remains FCC.

*This work is supported by the Harvard MRSEC (DMR-0820484), and the NSF (DMR-1006546)

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Authors

  • Melaku Muluneh

    • Harvard University

  • Joris Sprakel

    • Wageningen University, The Netherlands
    • Wageningen University

  • Hans M. Wyss

    • Eindhoven University of Technology (a) Department of Mechanical Engineering, Materials Technology (b) Institute for Complex Molecular Systems
    • Eindhoven University of Technology, The Netherlands
    • Institute for Complex Molecular Systems and Department of Mechanical Engineering, Eindhoven University of Technology, 5600 MB Ein, The Netherlands

  • Johan Mattsson

    • University of Leeds, UK

  • David Weitz

    • Harvard University
    • Department of Physics and Division of Engineering and Applied Science, Harvard University, Cambridge, MA 02138
    • School of Engineering and Applied Sciences, Harvard University
    • Department of Physics, Harvard University, Cambridge, MA, United States
    • Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA