Study On Preparation Of Soluble Polyaniline And Luminescence Properties Of Its Nanocomposite Film With CdS

Conducting polymer-chalcogenide semiconductor nanocomposite luminescence film attracts more and more attention because it can overcome the disadvantages of inorganic and organic materials and can improve the efficieny and life-span of luminescence. But the types of its matrix are limited. It's proved that, polyaniline is a kind of hole-transport material and has luminescence character, but shortage of high performance for forming film supported by itself due to its poor solubility. But it is difficult to prepared polyaniline film. If the problem can be solved, polyaniline can act as a new type of matrix to prepare this kind of luminescence composite. In this paper, solubility of polyaniline in polar solvent was improved by sulfonation and copolymerization, and poly(aniline-co-o-anthranilic)(PAOAA) film with good quality was prepared. And nano-CdS/PAOAA composite luminescence film was further prepared with in-situ synthesis method. By way of sulfonation on emeraldine base polyaniline, sulfonated polyaniline(SPAN) was prepared. Effect of reaction conditions on conductivity and sulfonation degree of SPAN was discussed in detail. The relationship of sulfonation degree and solublility was also discussed. The conductivity of SPAN reaches above 10-2S/cm and the largest solubility in DMF is 12.33%. PAOAA was synthesized by copolymerization of aniline(An) with o-anthraniline(OAA). The solubility and conductivity of PAOAA were tested and the results indicate that monomer ratio of OAA/An has great effect on them. Compared with conductivity and solubility of SPAN, the conductivity of PAOAA goes down slightly(about 10-3S/cm), but the solubility is improved greatly, which can reach 100% in DMSO and NMP. The PAOAA film can be successfully prepared by using PAOAA solution in DMSO. By use of complexing function of -COOH on PAOAA chains, Cd2+ ions were introduced in PAOAA matrix through ion-exchang. Then nano-CdS/PAOAA composite film was prepared. CdS particles with different nanometers can be synthesized by changing the sulfonation conditions. Because of stabilization and steric hindrance function of PAOAA in the film, CdS particles have narrow particle sizes and can uniformly disperse in PAOAA, and mainly exist in amorphous state. The results of photoluminescence analysis indicate: the peak of exciting spectrum of nano-CdS/PAOAA composite film lies on its high-frequency peak of UV-Vis absorption spectrum; use a 350nm excitation light, a stronge PL emission emerges around 430nm and 520nm, which originated from PAOAA and CdS nanoparticles together; with the increase of CdS particle size and its content, the characteristic peak of CdS get stronger in PL spectra of nano-CdS/PAOAA composite film. Therefore, nano-CdS/PAOAA composite film with luminescence was prepared sucessfully based on polyaniline derivative PAOAA as a matrix.