Thermosensitive hollow capsules based on thermoresponsive polyelectrolytes

Thermosensitive hollow capsules were successfully fabricated by the layer-by-layer deposition onto colloid particles of oppositely charged diblock copolymers each containing a poly (N-isoproprylacrylamide) (PNIPAM) block and by the subsequent decomposition of the core. The multilayer growth was characterized by electrophoresis and single particle light scattering. By combining confocal microscopy observation and FRAP measurements, we showed that the morphology and the permeability of the capsules change upon heating in aqueous solution. The decrease of size accompanied by a decrease of the permeability with increasing temperature was attributed to structural rearrangements in the shell. However, this process is only partially reversible upon cooling, limiting the thermoresponsive behavior of the capsules.