Temperature and pH dual responsive crosslinked polymeric nanocapsules via surface-initiated atom transfer radical polymerization

Novel intelligent nanocapsules with temperature-responsive crosslinked shells and pH responsive brushes on their inner walls have been designed and prepared by using the “polymerization from template” strategy via the surface-initiated atom transfer radical polymerization (SI-ATRP) technique with silica nanoparticles as the sacrificial templates. The two-steps sequential SI-ATRP procedure provided the poly(tert-butyl acrylate) (PtBA) brushes on the inner walls of the temperature-responsive crosslinked poly(N-isopropylacrylamide) (PNIPAm) shells. Then the ester groups in the nanocapsules were transformed chemically into carboxyl groups after etching the silica templates with HF. The environmental responsive characteristics of the dual responsive crosslinked hollow nanocapsules (DRCNs) were characterized with dynamic light scattering (DLS) system in aqueous solutions. The intelligent nanocapsules are expected to be used for the controlled releasing of drugs.