Dual Light-emitting Properties Of Hydroxy Polylactic Acid And Waterborne Polyurethane Based On Benzophenone Derivatives

The dual-emission polymers prepared in this paper have good application prospects in biological testing.This paper aims to obtain a better optical performance, more convenient processing, less toxica and emission at room temperature phosphorescence/fluorescent material.The contents and results are as follows:The first job is designed and synthesized (4-((2-hydroxyethyl) (methyl) amino) phenyl) benzophenone (NBP) and (4-chlorophenyl) (4-((2-hydroxyethyl) (methyl) amino) benzophenone (NBP-Cl), and the structure characterized by infrared spectra (FTIR) and nuclear magnetic resonance spectra (1H-NMR and 13C-NMR) and the optical properties of the moleculars were characterized by UV-VIS-NIR spectrograph and spectrofluorimeter..NBP and NBP-Cl are very similar:a chlorine atom substituted on its UV absorption slightly red shift at 365nm UV irradiation, both of the two moleculars are blue-green fluorescence in dichloromethane solution and they will appeare blue-green fluorescence at 77K, but the phosphor is not obvious; solid powders are both green fluorescence, which aslo emit blue-green fluorescence at 77K, whileas the phosphor is not obviou.The fluorescence lifetime of NBP monomers in the solid state is 4.86 × 10-8 seconds,while the fluorescence lifetime of NBP-methylene chloride solution is 3.754 × 10-9 seconds; The fluorescence lifetime of NBP-Cl monomer in the solid state is 2.5 × 10-7 seconds, while the fluorescence lifetime of NBP-Cl-methylene chloride solution is 8.01 × 10-10 seconds.Then we use the prepared different molecular weights and dual light-emitting properties of polylactic acid (PLA), which polymerized by L-lactide ring-opening polymerization with NBP and NBP-Cl respectively to be the initiators, and the choice of IR,1H NMR and 13C NMR spectra were used to characterize the structure of the PLA and molecular weight calibration of the PLA. With the increasing of the molecule weight of NPB-PLA and NBP-Cl-PLA, the higher the thermal decomposition temperature appeared, and all of the different molecular weights of pla showed a strong crystalline. With the increase of the content of NBP, maximum UV absorption peak (λmax) of NPB-PLA red-shifts; and NPB-Cl-PLA,whice contains chlorine atoms chromophore, appears red-shift.Under the UV light irradiation, strong blue-green fluorescence(in the air) and blue-green fluorescenc/green mixed phosphorescence (in a vacumn) can be observed.The phenomenon indicate that NBP-PLA1-10 are both fluorescence and phosphorescence dual light-emitting polymer. Likewise NBP-Cl-PLA also showed the same properties.Then we use PLA containing mixed phosphorescence-fluorescence properties as the soft segment of waterborne polyurethane, as well as NBP and NBP-Cl waterborne polyurethane were prepared and characterized the structure by IR, and characterized the molecular weight by GPC; DSC test showed that when the ratio of hard and soft segments is consistent, the greater the molecular weight of the polyurethane is, the Tg of hard segment is higher; Malvern test results show that the choice of PLA as soft segment of waterborne polyurethane increase the particle size. All waterborne polyurethane that we prepared possess good dual emission performance.As the increase of the WPU-NBP relative molecular mass, the excitation peak of aqueous WPU fluorescence spectra blue shifts, while the emission peak of the film in air and in vacuum appear redshift phenomenon; In the case of the presence of chlorine atoms, WPU excitation peak and fluorescence emission peak have obvious redshift.