Properties of core-shell structured nanopowders of molecular crystals fabricated by dry grinding

摘要

A generic way to prepare nano-sized molecular crystals in large scale is described. The dry mechanical grinding of a mixture of molecular crystals with surface-modified Stober silica nanoparticles gave voluminous hybridised powders with core-shell nanostructures, which were revealed by TEM and EFTEM measurements. Fluorescence spectra of the hybrids of emissive crystals suggested that crystal structures of the bulk are preserved even after the milling. Calorimetric measurements disclosed that melting points of crystals are lowered as a result of the nanohyhridisation and that the depression of melting point and heat of fusion are reversibly proportional to shell thickness.