Synthesis, Optical And Structure Properties Of Oxadiazole Substituted And Siloxane Blocked PPV

Polyphenylene Vinylene (PPV) and its derivatives are an important polymer electroluminescent material. PPV consists of benzene and ethylene alternated, which form a large conjugated polymer chain. PPV has a lot of defects, for example, it is insoluble and has poor thermal stability, low quantum efficiency and so on. The researchers have to modify the structure of PPV for application. Modification focus on two aspects, one is to introduce function group in the side chain, the other is to copolymerize with other group in the main chain.The usual method to modify the side chain is to introduce group on the 2,5 position of benzene. This would not only improve the transfer capability of PPV but also adjust the emission wavelength. The main chain modification refers to copolymerize with conjugated or unconjugated group to regulate the conjugation length, which aims to prevent fluorescence quenching as well as enhance thermal stability.Using monomer 1 and 2 as reagents, we succeeded in introducing Oxadiazole group in the side chain and Siloxane group in the main chain of PPV by Gilch reaction. Finally we obtained two novel PPV derivatives (MSiO-Oxa-PPV and PSiO-Oxa-PPV), which structures are confirmed by FT-IR. The new type organic electroluminescent materials have excellent performance in the luminescent properties and thermal stability, more than that is we get a novel blue light-emitting material. We have studied the polymers' optical properties and structure properties, got the conclusions as followed:1. UV-vis shows oxadiazole group absorption is at 300nm, PPV main chain absorption is at 410nm, PPV absorption peak is very weak, indicating that PPV main chain has been blocked;2. FL shows that the polymers'emission wavelength is at about 480nm, which belong to the blue wavelength;3. XRD shows that the polymers'structure are arranged orderly;4. SEM shows microstructure of the polymers are nano-scale grain.5. GPC shows statistical molecular weight for MSiO-Oxa-PPV and PSiO-Oxa-PPV is 110,000 and 10,000, which indicates we have obtained two polymers;6. DSC shows Tg of MSiO-Oxa-PPV and PSiO-Oxa-PPV are 165℃and 200℃, which perform an excellent thermal stability;...