Controlling the size and swellability of stimuli-responsive polyvinylpyrrolidone–poly(acrylic acid) nanogels synthesized by gamma radiation-induced template polymerization

Polymeric pH-sensitive hydrogel nanoparticles (nanogels) of narrow size distributions were directly prepared by gamma radiation-induced polymerization of acrylic acid (AAc) in an aqueous solution of polyvinylpyrrolidone (PVP) as a template polymer. The driving force of PVP/PAAc nanoparticles formation was attributed to the complexation between PAAc (proton-donor) and PVP (proton-acceptor) through the hydrogen bonding interaction. In addition to the hydrogen bonding interaction between the components, the nanoparticles are further stabilized by covalent bonds as a result of the radiation-induced crosslinking process. Particle size and swellability of the prepared nanogels can be controlled by feed composition and concentration, PVP molecular weight as well as irradiation dose, temperature, and atmosphere. The prepared PVP/PAAc nanogel particles were characterized by dynamic light scattering (DLS), viscometry, transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques.