Facile synthesis of poly N-isopropylacrylamide/acrylamide-quantum dots hybrid hydrogels and their fluorescence temperature sensitive behaviors

Poly (N-isopropylacrylamide) (PNIPAM) is an intelligent hydrogel which exhibits volume transition in response to temperature change. This work reports the PNIPAM/AM-QDs hybrid hydrogels, in which N-isopropylacrylamide, acrylamide as monomers and CdTe/CdS quantum dots (QDs) as filler, are prepared by glow discharge electrolysis plasma (GDEP). The hydrogels are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), FTIR spectra, differential scanning calorimetry (DSC) and PL spectra, as well as the swelling rate, temperature sensitivity and fluorescence reversibility. The results show that the PNIPAM hydrogels and QDs are cross-linked by coordination bond, and the QDs are well dispersed and combined firmly in the networks of the hydrogels. The phase transition temperature of PNIPAM/AM-QDs hybrid hydrogels is 32.5°C. The fluorescence intensity of hydrogels is 1490 a.u. and 20 a.u. at 20 and 40°C, respectively. Furthermore, the luminescence intensity of hydrogels is almost not weakened after five heating-cooling cycles, which should be used as a temperature-controlled light switch.