The Preparation And Emission Color Tuning Of Fluorescent Microspheres And Nanoparticles Based On Poly(P-Phenylenevinylene)

Fluorescent microspheres and fluorescent nanoparticles have been widely used in many fields as a kind of new fluorescent materials, such as sensing and detecting, optical encoding, bioimaging, photoelectric devices and etc. In recent years, conjugated polymers have received continuous interests in the study as fluorophors, because of their large advantages in processing and optical properties over small fluorophor molecules. In this thesis, fluorescent microspheres and nanoparticles were prepared with poly(p-phenylenevinylene)s(PPVs) as the fluorophor, and the tuning of emission colors of both microspheres and nanoparticles were realized.System 1: Different from the preparation of fluorescent microspheres with PPV as the fluorophor in our previous study(the PPV precursor was converted into PPV by the thermal elimination in solid state), the method of heterogeneous catalytic thermal elimination was used and the influences of elimination time and temperature on microspheres were studied. The emission of microspheres red shifted with the increasing of elimination temperature. The heterogeneous catalytic thermal elimination here has several advantages over the elimination in solid phase with lower elimination temperature needed and more controllable preparation process.System 2: The method that the sulfonium groups in the polymer precursor(pre-PPV) are partly substituted by relatively stable methoxy groups followed by selectively elimination of sulfonium groups to control the conjugation length in the polymer backbone was studied. That the fluorescence color of PPV and the microspheres coated with PPV tuned from green to blue was realized simply and effectively through this method, and the tuned fluorescent colors displayed more stability compared with those obtained via changing the elimination temperature in system 1.System 3: The PPV nanoparticles were prepared by self-assembly of pre-PPV and PPV chains during the thermal elimination process. Based on the method for color tuning in system 2, PPV nanoparticles with different fluorescence color ranging from blue to green could be obtained. The size of PPV nanoparticles was found to be influenced by the degree of substitution.