Synthesis And Properties Of Luminescent Liquid Crystals Based On Carbonized Polymer Dots

As an excellent fluorescent substance,carbonized polymer dots（CPDs）are widely used in organic light emitting diode（OLED）,fluorescent probe and bioimaging because of its high fluorescence quantum efficiency,low cost,chemical inertia,low cytotoxicity,photo stability and excellent biocompatibility.In this thesis,two kinds of solid-state luminescent liquid crystals are prepared by grafting traditional liquid crystal molecules onto the surface of CPDs.The relationship between structure and properties of luminescent liquid crystals and the effect of surface-modified liquid crystals on their optical properties are further studied.The specific work mainly focuses on the following two aspects,1.The structure and morphology of CPD-LC were characterized by means of NMR(¹H NMR,¹³C NMR),Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscopy（TEM）and dynamic light scattering（DLS）.The phase behavior and liquid crystal properties of the sample are investigated by thermogravimetry（TGA）,differential scanning calorimetry（DSC）,polarizing microscope（POM）and one-dimensional wide-angle X-ray diffraction（1D-WAXD）.The results show that CPD-LC exhibit excellent liquid crystal behavior by grafting rod-like liquid crystal molecules onto the surface of CPD.In addition,the photophysical properties of CPD-LC are studied by UV,PL and PLQY.The results show that CPD-LC exhibit stronger luminescence in the solution state and higher luminescence efficiency in the solid film state.The results show that the obtained CPD-LC produced show excellent liquid crystal performance and high luminous efficiency in the aggregation state.2.Furthermore,a carbonized polymer dots-luminescent liquid crystal（CPD-Chol）grafted with cholesterol is designed and synthesized.The structure and morphology of CPD-Chol are also investigated by ¹H NMR,¹³C NMR,FT-IR,XPS,TEM and DLS.Then the phase behavior and liquid crystal properties of the sample are investigated by TGA,DSC,POM and 1D-WAXD.CPD-Chol grafted with cholesterol also has liquid crystal property.The results of UV-Vis and PL show that CPD-Chol exhibits higher luminescence efficiency in both solution and solid-state film.It means that the obtained strategy to prepare luminescent liquid crystal by grafting liquid crystal units on CPD surface is effective,which opens a new way for the research of luminescent liquid crystal.