共轭支链含腈基的聚对苯乙烯衍生物的合成及光谱特征

Synthesis,Characterization and Optical Properties of Cyano-containing Conjugated Side-chains PPV Derivatives

通过HECK法共聚将腈基引入聚对苯乙烯(PPV)的共轭支链,得到聚合物D iCN-PPV。通过核磁共振(1H-NMR)、质谱(MS)、元素分析及GPC确定了组成和分子量。探索了聚合反应时间和温度对聚合物分子量及产率的影响。结果表明,该聚合物具有较高的热稳定性(Td>247℃),在100℃反应62 h可以得到产物分子量Mn=1.76×104,分散度Pd=1.9,产率50%。以紫外吸收光谱及荧光光谱分析了该聚合物溶液及其膜的基本光谱特征,表明D iCN-PPV中D-A(Donor-Acceptor)给受体的结构发生分子内的能量转移,从而导致了新的能级结构。它的荧光为红光λm ax=645 nm,是一种潜在的有机红光新材料。

Since electroluminescence （EL） for an organic semiconductor was reported, Poly（ phenylenevinylene） （PPV） derivates are the most promising materials for organic light-emitting diodes （OLEDs）. To realize more brightness and luminescence efficiency, the strong electron-withdrawing CN groups were introduced to conjugated side chains because cyano group posses strong electron-deficiency and electron-transporting characteristics. Moreover, bigger side chains structures could reduce aggregation state in solid film, which is suitable to OLEDs. A new alternating copolymer DiCN-PPV containing bis （2-phenylacrylonitrile） -2,5-dibromo-1,4- phenylene） and 1-（heptyloxy）-4-（octyloxy）-2,5-divinylbenzene was successfully synthesized via Heck polymerization with moderate yields. Since Poly（phenylenevinylene） （PPV） posses strong electron-rich and holetransporting characteristics and cyano group is obviously a electron-deficiency material, the donor-acceptor conjugated structures could change the energy band gap and light-emitting color. The polymer was charactered by 1^H-NMR, MS, element analysis and GPC. It possesses good thermal stability （ Ta 〉 247 ℃ ） and is adequate for the fabrication processes of optical-electric devices. In the optimized polymerization reaction conditions, the polymer of DiCN-PPV （ Mn = 1.76 × 10^4 ,Pa = 1.9, production rate 50% ） was soluble in common organic solvents . The absorption spectrum of DiCN-PPV solution shows two absorption peak and that of film shows one absorption peak, which means a new energy level was formed after energy transfer between donor and acceptor units. Moreover, the onset of absorption edge is located at 623 nm in solid film, which is red shift by 80 nm than that in solution because more aggregation conformation were formed in solid state. Photoluminescence（PL） spectra coincide with above conclusion and the fluorescence peaks of DiCN-PPV in solution and solid film, were at 573 nm and 645 nm, respectively. Because of λmax n =645 nm in solid film, it can be a potential red light-emitting material for fabrication of organic light-emitting diodes （OELD）.