Design And Synthesis Of Large Planar Conjugated Polymers

Generally speaking, conjugated polymers own unique optical and electrical properties.As polymers, they also possess design-ability and good thermal stability. For some conjugated polymers, although the strong rigidity brings about some problems, for example, hard to be processed and poor flexibility, it usually can be solved by connected with flexible chain segments. So conjugated polymers have been highly focused on by academic and industrial fields, and they have been used in fields such as photovoltaic cells, image sensing, field-effect transistor, etc.Planar conjugated polymers are an important kind of conjugated polymers. The main chain of planar conjugated polymer is made up of cyclic structures which almost completely limited the repeating units to freely rotate, at the same time, both configurational isomerization and conformational isomerization have been almost eliminated. As a result, the polymers possess larger conjugated planes and larger electron delocalization range which are good for improving the polymers' fluorescence quantum efficiency and conductivity.Unfortunately, structural defects are often produced during the chemical reactions. The existence of structural defects has an important influence on the polymers' properties just like the optical and electrical properties, thermal stability and other properties. What's more,planar conjugated polymers have strong rigidity which is not good for dissolving and processed.Aimed at the problems existed in planar conjugated polymers, we take2,7-di-tert-butylpyrene as the basic material to prepare the monomer carrying with borate,then the monomer and halogenated aromatic hydrocarbons are used as reactants to synthesize the planar conjugated polymers by the Suzuki coupling reaction and twice ring-closing reactions. Pyrene itself is a planar conjugated micro-molecule which owns unique optical and electrical properties. The introduction of pyrene can reduce the reactive sites during the ring-closing reactions as well as reduce the chance of structural defects generated in the course of reaction. Based on this idea, some studies have been carried out, as follows:1. The compounds a1 and a2 were obtained by the chemical reaction of 2,7-di-tertbutylpyrene and bis(pinacolato)diboron; 1-bromo-4-tert-butylbenzene was used as the starting materials to synthesize the compound b3,and the compound c3 was synthesized from the very beginning material 4-tert-butylaniline.2. Compound s1 was prepared by the Suzuki reaction, then the goal compound x1 was obtained by twice ring-closing reactions. CF3 COOH was used as catalyzer in the first ring-closing reaction to get compound m1, and Mo Cl5 was used in the second one to produce x1. s2, m2, x2 were obtained respectively by the methods used in the synthesis of s1, m1, x1.3. P1, P2 and P3 were also synthesized respectively by the methods used in the synthesis of s1,m1, x1.4. We investigated their UV-vis absorption and fluorescence spectra properties, the data shows that red shift phenomenon are happened in both the polymers and oligomers. The more the ring-closing reactions have been done, the more obvious that red shift phenomenon is happened. The thermal properties of the polymers and model compounds were tested by using thermogravimetric analyzer(TGA). The result showed that both the polymers and oligomers have good thermal stability. Cyclic voltammetry was applied to test their electrochemistry properties. The band gap of x1 is 1.78 eV, and the band gap of x2 is 2.90 eV. For the polymers have poor solubility in dichloromethane, the electrochemistry properties have not been tested out by Cyclic voltammetry. And the solubility of polymers needs to be further improved.