Unusual thermo-responsive behaviors of poly(NIPAM-co-AM)/PEG/PTA composite hydrogels

Abstract Poly(NIPAM- co -AM)/PEG/PTA composite hydrogels were synthesized by aqueous copolymerization of N -isopropylacrylamide (NIPAM) and acrylamide (AM) in the presence of polyethylene glycol (PEG) using potassium persulfate (KPS) as an initiator at 70 °C. N,N′ -methylenebisacrylamide (BIS) and phosphortungstic acid (PTA) acted as chemical and physical crosslinking agents, respectively. The hydrogel was found with unusual and reversible thermo-responsive behaviors. The hydrogel exhibited a higher critical solution temperature (UCST) of 59.6 °C which can be readily tuned by the amount of PEG. This work provided a facile way to adjust the phase transition temperature of hydrogels and a new insight to develop novel stimuli-responsive hydrogels.