Temperature-responsive ionic-crosslinked polymeric nanocapsules via 'self-templating' approach

The temperature-responsive ionic-crosslinked polymeric nanocapsules (TRICNs) were fabricated via the 'self-templating' approach from the poly(tert-butyl acrylate-co-N-isopropylacrylamide-co-acrylic acid) (poly(tBA-co-NIPAm-co-AA)) terpolymer nanoparticles prepared via the emulsifier-free emulsion polymerization. After the surface carboxyl groups of the terpolymer nanoparticles were crosslinked with calcium ions, the TRICNs were achieved after the cores of the shell-crosslinked nanoparticles had been etched by being dissolved with acetone. Transmission electron microscope (TEM) showed the particle size of the individual nanocapsules was about 200 nm with the inner diameter of about 140 nm. The lower critical solution temperature (LCST) of the TRICNs was found to be about 31°C from the dynamic light scattering (DLS) analysis. Furthermore, the nanocapsules could disintegrate in acidic media while they were stable in the neutral or alkaline media.