Shape-memory nanoparticles from inherently non-spherical polymer colloids

Samples of polymeric materials generally have no intrinsic shape; rather their macroscopic form is determined by external forces such as surface tension and memory of shear ( for example, during extrusion, moulding or embossing). Hence, in the molten state, the thermodynamically most stable form for polymer ( nano) particles is spherical. Here, we present the first example of polymer nanoparticles that have an intrinsic non-spherical shape. We observe the formation of high-aspect-ratio ellipsoidal polymer nanoparticles, of controlled diameter, made from main-chain liquid crystalline polymers using a mini-emulsion technique. The ellipsoidal shape is shown to be an equilibrium ( reversible) characteristic and a direct result of the material shape memory when a liquid crystal nanoparticle is in its monodomain form.