Syntheses And Properties Of Fluorescent Graphene-Poly(vinyl Alcohol) Polymer Materials

Fluorescent polymer materials have excellent photophysical and photochemical properties due to the excellent properties of the polymer and fluorescent substance,and have been used as new functional materials in many fields,such as biological fluorescent labeling,fluorescent probe detection and analysis technique,fluorescent chemical sensor,nonlinear optical devices and photoconductive resins and so on.In this paper,dye intermediate was prepared from p-hydrazino-benzenesulfonic acid,and the squaraine dye(SD)was synthesized by condensation of the dye intermediate and squaric acid.SD as the parent compound was combined with p-aminoazobenzene or benzylamine to obtain two squaraine dye derivatives.SD-PVA binary fluorescent polymer materials and SD-HG-PVA ternary fluorescent polymer materials were synthesized by the combination of the squaraine dye with polyvinyl alcohol(PVA)and/or hydrophilic graphene(HG)in solutions via physical method which carried out by the mixing of SD,PVA and/or HG under ultrasound at room temperature and chemical method by the mixing of the active ester of SD,PVA and/or HG stirring at room temperature for 24 h.The products were characterized by SEM,TEM,XRD,AFM,IR,UV-Vis and fluorescence spectra.The results showed as follows:(1)The maximum UV-Vis absorption wavelength of SD in water was 631 nm,the maximum fluorescence emission wavelength was 654 nm,and the degradation rate was 43.46% after irradiation 120 min under UV lamp.(2)After SD composited with PVA via physical or chemical methods,the maximum UV-Vis absorption wavelengths shifted to 645~649 nm,the maximum emission wavelength shifted to 666~668 nm,and the fluorescence intensity significantly increased.the photo-stability was significantly enhanced due to the degradation rates decreased(36.72 %,28.66 %);(3)After the modification by HG,the degradation rates were further decreased(3.47 %,3.34 %),and the weight loss rate at 230-500 ℃ also decreased,indicating that the addition of HG not only enhanced the photo-stability of the fluorescent composites butalso enhanced the thermo-stability.SEM,TEM and AFM showed that the surface of the composites was smooth and uniform,and the fracture surface clearly revealed the layered-structures.The composites as new type of composite materials could be used widely in many fields due to the excellent fluorescence properties,photo-and thermo-stability and mechanical properties.