In this study, a poly(N-vinylpyrrolidone)-graft-poly(N-isopropylacrylamide) hydrogel
(PVP-g-PNIPAM) was synthesized through the ‘‘grafting from” process. Grafting of temper-
ature responsive poly(N-isopropylacrylamide) (PNIPAM) brushes was carried out from the
poly(N-vinylpyrrolidone) (PVP) synthesized with free radical polymerization and function-
alized with ATRP initiator, PVP–Br, which was performed through a bromination reaction
between pendant allylic groups of the PVP and N-bromosuccinimide (NBS). The structure
of the initiator and PVP-g-PNIPAM was characterized by ultraviolet and visible (UV/Vis)
absorption, nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infra-
red (FTIR) measurements. Scanning electron microscope (SEM) morphology measurement
displayed some dendritic grafted chains dangling onto the pore wall of the hydrogel.
The characteristic in response to the change in environmental temperature was investi-
gated by the ?uorescence anisotropy and UV/Vis transmittance measurements. The results
showed that the PVP-g-PNIPAM hydrogel exhibited rapid response to the change in envi-
ronmental temperature due to free and mobile graft chains compared with the P(VP-co-
NIPAM) hydrogel, which was prepared by free radical copolymerization in this work.