New insights into the nucleation and growth of PS nodules on nanoparticles by 3D cryo-electron tomography.

Taveau, Jean-Christophe; Nguyen, David; Perro, Adeline; Ravaine, Serge; Duguet, Etienne; Lambert, Olivier · Soft Matter · 2008

basic_science · Level V

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Abstract

The nucleation and growth of polystyrene (PS) nodules on 170 nm silica seeds under emulsion-polymerization conditions have been investigated for the first time by cryo-electron tomography. 3D arrangements were reconstructed from samples collected at several polymerization times (from 5 to 120 min). Early samples display the presence of small PS nodules bound to silica particles in a random distribution. For longer polymerization times, the number of PS nodules per silica seed decreases leading to octopod-like morphologies. The tomographic method allowed us to measure the contact angle that the growing PS nodules form with the silica bead surface. The average value of 142.4° remains constant over all of the observed period of the polymerization reaction. This contact angle appeared to be one of the key parameters for controlling the morphology of PS-silica biphasic particles.