Synthesis And Characterization Of New Type Schiff Based Thiophene Conjugated Copolymers

Polythiophene and its derivates have been aroused much interest due to theirbroad application prospects in hi-tech fields, such as polymer light-emitting diodes,biosensors, organic transistors, nonlinear optical devices, polymer solar cells andelectrochromic materials. Phenylacetylene polymers have excellent optical properties;they are widely used in the luminescent field. In addition, introduction of variousfunctional group into thiophene monomer which in the main chain can control thecopolymers energy band gap. Therefore, in this paper,3-formylthiophene as mainmonomer, and two monomers which containing Schiff base in the side chain weresynthesized by Schiff base reaction. Schiff based thiophene monomers werecopolymerized with alkoxy substituted phenylacetylene, pyridine,3-butyl-thiophene,azobenzene by using metal complexes catalysis (Sonogashira and Yamamoto reaction),and its photoelectric properties were preliminary investigated and studied. This articleis concluded five parts as follows:(1) Development situation of conjugated polymers, the research background,significance, application prospect of polythiophene and polyphenylacetylenederivatives were briefly dicussed. The conjugated polymer’s synthetic method and thegeneral properties of the Schiff base compounds were briefly introduced.(2)2,5-dibromo-3-formylthiophene as main monomer, three kinds of copolymerwhich containing3-formylthiophene and alkoxy substituted phenylacetylene unitswere synthesized by Sonogashira reaction, and photoelectric properties of thecopolymer were preliminary discussed. The study found that as increase side chainsof copolymers could improve the copolymers each properties. The solubility andquantum efficiency of the copolymer are more obvious; they dissolved in the commonsolvents, the quantum efficiency of copolymer PTC-PE12in the solution achieved to62.7%. In addition, these copolymes have a better molecular stacking, when methanolcontents in their THF solution were0%,50%and80%, they emits green, yellow and orange light respectively.(3)4-amino-1,2,4-triazole was introduced into thiophene as side chain by Schiffbase reaction. This Schiff based monomer was copolymerized with alkoxy substitutedphenylacetylene. The chemical structure of the copolymers was characterized andconfirmed by1H-NMR, FT-IR, GPC. The optical and electrical properties of thecopolymers were verified by UV-vis, PL and cyclic voltammetry. The study foundthat the copolymers in THF solution emit green light, with maximum emission peak at495-505nm and545-560nm in solution state and film state respectively. Thefluorescence quantum efficiency of copolymer PTT-PE4reached to42.7%.(4) Three kinds of copolymer which containing3-methyne(4-butoxyaniline)thiophene and alkoxy substituted phenylacetylene were synthesized by Sonogashirareaction. The structure and electrochemical properties of the copolymers werecharacterized and studied by FT-IR, GPC, UV-vis and cyclic voltammetry. The resultshowed that the copolymers have not fluorescence properties, their maximum UV-visabsorption peaks were at410-417nm.(5)2,5-bromo-3-methyne(4-butoxyaniline) Thiophene as the the main monomer,with2,5-dibromo-3-butyl-thiophene,2,5-dibromopyridine and4-4’-iodine azobenzenewere copolymerized by Yamamoto reaction respectively, the optical and electricalproperties of three copolymers were studied. The study showed that copolymerPⅠand PⅡemit yellow-green light in chloroform solution. The energy band gaps ofthe copolymers were1.67eV,1.26eV.