Disclosing the nature of thermo-responsiveness of poly(N-isopropyl acrylamide)-based polymeric micelles: aggregation or fusion?

The apparent size increase of poly(N-isopropyl acrylamide) (PNIPAM)-based polymeric micelles upon heating was usually ascribed to their volume growth or aggregation in aqueous solution. Herein we designed a photo-cross-linkable PNIPAM-based copolymer and proposed another thermo-responsive behaviour - fusion, which is disclosed by transmission electron microscopy (TEM) after in situ fixing morphologies at desired temperatures.