Mesospheres in nano-armor: probing the shape-persistence of molten polymer colloids.

We utilize Brillouin light scattering to investigate the shape-persistence of polystyrene-silica core-shell particles by recording their vibrational eigenmodes as a function of temperature. The thin silica shell (tens of nm) protects the polymer core from changing its spherical shape at temperatures above its glass transition temperature Tg, readily obtained from the same experiment. The rigidity of the confined core is enhanced compared to the bare core.