Electrosynthesis Of Conducting Polythiophene Derivatives And Investation Of The Electrochromic Properties

Conducting polythiophene derivatives with good electrochromic properties havepotential applications in the electrochromic devices. Electrochemical polymerizationhas been proved to be one of the most useful approaches for conducting polymersynthesis. In this dissertation, poly(3-bromo-4-methylthiophene)(PBrMeTh),poly(3,4-dibromothiophene)(PDBrTh), poly(3,3'-dimethyl-2,2'-bithiophene)(PDMeBTh) were successfully prepared by electrochemical polymerization in borontrifluoride diethyl etherate (BFEE), and the corresponding characterizations of thesehigh-quality correspondingpolymers were discussed. The electrochromic properties ofthesehigh-qualitycorresponding polymers werealso investigated.1. Poly(3-bromo-4-methylthiophene) (PBrMeTh) films were prepared in borontrifluoridediethyl etherate (BFEE)byelectrochemical polymerization. PBrMeTh filmsobtained from this medium showed good electrochemical behavior and good thermalstability with conductivity of 3×10-2 S cm-1. FT-IR spectroscopy showed thatpolymerization occurred atC(2) and C(5)positions.Fluorescent spectral studies indicatethat PBrMeTh film is a good blue-light emitter. The electrochromic properties of thepolymer films were investigated, indicating that PBrMeTh is a good electrochromicmaterial.2. High-quality poly(3,4-dibromothiophene) (PDBrTh) films were preparedelectrochemically by direct anodic oxidation of 3,4-dibromothiophene (DBrTh) inboron trifluoride diethyl etherate. The conductivity of this polymer is 0.46 S cm-1.PDBrTh films obtained from this medium showed good electrochemical behavior andgood thermal stability. Spectroelectrochemistry analysis of polymer revealed that this polymer film has good electrochromic properties. Moreover, dual type electrochromicdevice of PDBrTh with poly(3,4-diethylenedioxythiohene) (PEDOT) was constructed.Thiselectrochromicdeviceshows goodoptical contrast,distinctivecolor changes withtheabilityofgoodswitchingtimesandhashighcolorationefficiency.3. High-quality poly(3,3'-dimethyl-2,2'-bithiophene) (PDMeBTh) weresynthesized electrochemically in borontrifluoride diethyl etherate(BFEE) for the firsttime.Theconductivityofthepolymeris5.38 S cm-1.Characterizationsof theresultingpolymerwereperformedbycyclicvoltammetry,FT-IR,scanningelectronmicroscopy.Moreover, electrochromic properties of the polymer films were investigated. Thedual-type polymer electrochromic devices based on PDMeBTh and PEDOT were alsoconstructed. The colour of this electrochromic devicecan change from orange-yellowtobluerepeatedly,indicatingthatPDMeBTh isagoodelectrochromicmaterial.