One-pot synthesis of microcapsules with nanoscale inclusions

Temperature responsive poly(N-isopropylmethacrylamide) (pNIPMAm) microgel capsules around 1 µm containing multiple poly(N-isopropylacrylamide) (pNIPAm) nanoinclusions were prepared. This structure was achieved through the addition of a cross-linked pNIPMAm shell to stable, monodispersed aggregates of pNIPAm chains. This one-pot synthetic approach resulted in core/shell microgels at high temperature wherein only the shell (pNIPMAm) component contained stable, covalent cross-links between chains. Thus, upon decreasing the temperature following synthesis, the majority of the encapsulated pNIPAm chains escaped from the shell, resulting in nearly hollow microcapsules. Remnant pNIPAm segments in the microcapsule then form nanoparticulate inclusions upon raising the temperature.