Azobenzene-terminated PNIPAM (PNIPAM-AZO) with temperature and light dual-sensitive properties was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAM) with azobenzene-containing trithiocarbonate (TTC-AZO) RAFT reagent
and the structure was confirmed by UV-Vis
FTIR and 1H-NMR spectroscopy.The thermosensitivity and photosensitivity of PNIPAM-AZO aqueous solutions were investigated.The results show that PNIPAM-AZO aqueous solutions have rapid and reversible trans-cis photoisomerization properties.The lower critical solution temperature (LCST) of PNIPAM-AZO is lower than that of poly(N-isopropylacrylamide) (PNIPAM)
and the LCST of PNIPAM-AZO decreases with the increase of both polymer number molecular weight and aqueous solution concentration
and increases as the molecular weight distribution broadens.The LCST of PNIPAM-AZO aqueous solutions of higher concentrations first decreases and then increases when the addition amount of -cyclodextrin (-CD) increases.However
for lower concentrations of PNIPAM-AZO aqueous solutions
the LCST first increases and then remains fairly constant.When subjected to ultraviolet (UV) and visible light irradiation alternately
the LCST of PNIPAM-AZO aqueous solution increases and decreases reversibly with a temperature amplitude of 0.7 K