In order to obtain functionalized PET lms with thermosensitive surface

thermoresponsive polymer

poly(N-iso-propylacrylamide) (PNIPAM) was grafted from the surface of PET films via surface initiated atom transfer radical polymerization (SI-ATRP).Polar groups of carboxyl were produced on the surface of PET lms through alkaline hydrolysis and oxidation

then the ATRP initiator was immobilized on the surface of PET lms.And the ATRP was carried out at 30 ℃ in the presence of CuCl as a catalyst

ME6TREN as a ligand

and (30 ∶70

V/V) acetone/H2O as a reaction medium.The composition

structure and morphology of the surface of PET film and modified PET films were characterized by attenuated total reflection Fourier transform infrared spectroscopy (FTIR/ATR)

X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).And the surface properties of modified PET films were studied by contact angle measurements.The data showed that the structure and composition of the polyester film were changed after grafting

which demonstrated the successfully grafting of PNIPAM from the surface of PET films.Further more

with the increase of the reaction time

the grafting rate on the film surface increased

the grafting density increased to 0.239 mg/cm2 when the polymerization time was 16 h.It suggests that the SI-ATRP is a living radical polymerization.And the PET films modified by PNIPAM layers were stimulus-responsive with temperature indicating the successful functionalization of PET films.