Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and Experimental Study

F Camerin and MA Fernandez-Rodriguez and L Rovigatti and MN Antonopoulou and N Gnan and A Ninarello and L Isa and E Zaccarelli, ACS NANO, 13, 4548-4559 (2019).

DOI: 10.1021/acsnano.9b00390

Soft particles display highly versatile properties with respect to hard colloids and even more so at fluid fluid interfaces. In particular, microgels, consisting of a cross-linked polymer network, are able to deform and flatten upon adsorption at the interface due to the balance between surface tension and internal elasticity. Despite the existence of experimental results, a detailed theoretical understanding of this phenomenon is still lacking due to the absence of appropriate microscopic models. In this work, we propose an advanced modeling of microgels at a flat water/oil interface. The model builds on a realistic description of the internal polymeric architecture and single-particle properties of the microgel and is able to reproduce its experimentally observed shape at the interface. Complementing molecular dynamics simulations with in situ cryo-electron microscopy experiments and atomic force microscopy imaging after Langmuir-Blodgett deposition, we compare the morphology of the microgels for different values of the cross- linking ratios. Our model allows for a systematic microscopic investigation of soft particles at fluid interfaces, which is essential to develop predictive power for the use of microgels in a broad range of applications, including the stabilization of smart emulsions and the versatile patterning of surfaces.

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