Additive-free synthesis of poly(n-vinyl pyrrolidone) and poly(n-isopropylacrylamide) nanogels with controlled sizes

An easy method is proposed to prepare poly(vinyl pyrrolidone) (PVP) and poly(N-isopropylacrylamide) (PNiPAAm) nanogels with sizes less than 100 nm. The underlying principle dilute polymer solutions in acetone/water mixtures where acetone acts break tridimensional structure of water hence disrupting the H-bonds bridging coils causing separation shrinkage their sizes. Irradiation these by gamma-rays directly leads formation intramolecular crosslinks within resulting smaller precursor coils. While average size PVP irradiated only 236 nm, they were reduced about 44 nm when irradiation was carried out at near theta compositions. PNiPAAm also synthesized irradiating solutions. Multimodal coil distribution converted into monomodal 70 low dispersity addition acetone. such yielded 50 size. Stability followed for 1 year not showing any changes or distributions. Nanogels characterized dynamic light scattering, scanning electron microscopy, atomic force microscopy techniques.