The interplay between softness and liquid-to-solid transition is one of the more general problem in nature. In this contribution we present the phase behavior of water suspensions of ultra low crosslinked poly(N-isopropylacrylamide) microgels is studied in three and two-dimensions. In three-dimensions the phase behavior is comparable to the one of regular crosslinked microgels: Coexistence between crystals and liquid and fully crystalline samples are observed (Fig. 1A). Small-angle neutron scattering measurements of the single particle form factors show no failure of the spherical shape, both in crystalline and disordered, overcrowded samples. At the oil-water interface, the compressions isotherms and the analysis of the atomic force microscopy images of depositions at different concentrations of the microgels reveal that in two-dimensions the crystallization is suppressed (Fig. 1B). The reason for this is the wide variation of the particle bulk moduli together with the reduced mobility of the particles due to the confinement. Furthermore, the degree of compression can be used to switch the property of the depositions from the linear polymer-like to the one of a suspension of colloidal particles. Fig. 1 A) Crystals formed by the ultra low crosslinked microgels in water suspensions, three dimensional. B) Disordered arrangement of microgels imaged with atomic force microscope after deposition, two dimensional.

Ultra low crosslinked microgels are ordered in bulk and disordered in two-dimensions

255th National Meeting (2018)

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