SWELLABLE COLLOIDAL PARTICLES ARE SWELL

ABSTRACT
I will discuss soft matter experiments from my lab that explore fundamental questions about phase transition mechanisms and glasses. Briefly, soft materials deform easily when pushed, and some important examples include colloidal suspensions, emulsions, oil-water interfaces, polymer & surfactant solutions, liquid crystals, and mixtures thereof. Our recent work develops and takes advantage of a novel class of colloidal suspension composed of temperature-sensitive hydrogel particles; the temperature “knob” permits easy control of particle packing and simultaneous viewing by video microscopy [1]. These features, in turn, enable us to use colloidal crystals to answer fundamental questions about “how and where” crystal melting begins and about the mechanisms by which one crystal transforms to another during a solid-solid phase transition [2]. These features have also enabled us to critically explore open questions about disordered solids, e.g., how glasses rearrange internally when responding to mechanical stress [3]. After a broad introduction, I will describe these new experiments.

REFERENCES
[1] Yunker, P.J., Chen, K., Gratale, M.D., Lohr, M.A., Still, T., Yodh, A.G., Reports on
Progress in Physics 77, 056601 (Epub 2014).
[2] A.M. Alsayed, M.F. Islam, J. Zhang, P.J. Collings, A.G. Yodh, Science 309, 1207-1210 (2005); Y. Han, Y. Shokef, A. Alsayed, P. Yunker, T. C. Lubensky, A. G. Yodh, Nature 456,
898-903 (2008); Peng, Y., Wang, F., Wang, Z., Alsayed, A.M., Zhang, Z., Yodh, A.G., and
Han, Y., Nature Materials (Epub 2014).
[3] Chen, K., Ellenbroek, W.G., Zhang, Z.X., Chen, D.T.N., Yunker, P.J., Henkes, S., Brito, C., Dauchot, O., van Saarloos, W., Liu, A.J., and Yodh, A.G., Phys. Rev. Lett. 105, 025501 (2010); Chen, K., Manning, M.L., Yunker, P.J., Ellenbroek, W.G., Zhang, Z., Liu, A.J., and Yodh, A.G., Phys. Rev. Lett. 107, 108301 (2011); Still, T., Goodrich. C.P., Chen, K., Yunker, P.J., Schoenholz, S., Liu, A.J., and Yodh, A.G., Phys. Rev. E 89, (2014).