Preparation of nearly monodisperse pH-responsive microgels by radiation-induced dispersion polymerization

Nearly monodisperse poly(2-(diethylamino) ethyl methacrylate) (PDEA) microgels were prepared directly by radiation-induced dispersion polymerization in water/ethanol media using poly(vinylpyrrolidone) (PVP) as the stabilizer at room temperature under certain circumstance (appropriate ethanol/water ratio and monomer dosage), which afforded novel pH-responsive behavior with range of 600–2500 nm. This method takes the advantages of radiation-induction (no chemical initiator, temperature independent, uniform initiation with a high efficiency and so on) that may result in the formation of uniform polymer particles. PVP acted as not only a physical stabilizer, but also as a macromonomer to form the grafted copolymer, which was confirmed by the Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) and was important for the stabilization of microgels. The characterization (morphology, size and distribution, and swelling/deswelling kinetics) of PDEA microgels were carried out by the scanning electron microscope (SEM), dynamic light scattering (DLS) and turbidity studies.