Smart PVA-g-NIPAAm nanohydrogels preparation by a fast and facile free radical polymerization in dilute aqueous solution

Biocompatible stimuli-responsive nanohydrogels based on Nisopropylacrylamide (NIPAAm) is gaining attention for numerous potential applications in various biomedical andbiotechnological fields, including controlled drug delivery systems, artificial organs, on–off switches, and so on. [1–4].The work described here concerns the preparation of nanohydrogels of NIPAAm based on concepts of intra molecular collapsing in dilution condition by a novel method.In our method, free radicals are generated by hydrogen peroxide (H2O2) as initiator on linear biocompatible PVAchains at boiling point of water. From these sites, in dilute aqueous solution, where the distances between macromolecules are relatively high, NIPAAm graftpolymerization and intramolecular crosslinking can occurs simultaneously and lead to nanohydrogels formation. Furthermore, at temperature such above the LCST association of collapsed hydrophobic PNIPAAm chains creates additional physical crosslinking points.