Synthesis And Electrochromic Properties Of Conjugated Polymers Based On Propylenedioxythiophene Or Tetrabromoquinoxaline Phenanthro Phenazine

Conjugated conductive polymers have attracted extensive attention and research since they were discovered because of their excellent processability,various color changes,outstanding optical properties,fast response time,band gap is easy to control,they were widely used in smart windows,displays,sensors,military camouflage equipment,automotive rearview mirrors and other fields.Up to now,various types of conjugated conductive polymers have been widely reported by researchers,but their properties are different.In order to better explore conductive polymers,we have synthesized a series of polymers using novel monomers.As we all know,bandgap is considered as an important parameter to determine the electrochromic properties of polymers.Polymers with low bandgap are likely to become good conductive materials due to their intrinsic conductor or semiconductor properties in the ground state.There are a lot of ways to reduce the band gap,the most effective and commonly used method is D-A method.Because the electron-rich and electron-deficient groups alternately exist in the D-A type conjugated polymer backbone,electrons are transferred efficiently within the molecule,leading to the enhanced delocalization of?electrons,thereby obtaining a polymer with low band gap,which makes the polymer have excellent electrochemical and optical properties.In the second to fourth chapters of this study,we synthesized tetrabromoquinoxaline phenanthro phenazine and 3,4-propylenedioxythiophene as the main acceptor and donor units,respectively.In Chapter 2,PTPE-1,PTPE-2 and PTPE-3 were synthesized by thiophene,tetrabromoquinoxaline phenanthro phenazine and 3,4-propylenedioxythiophene by changing the ratio of donor to acceptor and chemical polymerization.Polymers PIPE-1,PIPE-2 and PIPE-3 were synthesized by dithiophene,tetrabromoquinoxaline phenanthro phenazine and 3,4-propylenediothiophene in Chapter 3.In Chapter 4,Polymers PBPE-1,PBPE-2 and PBPE-3 were synthesized by benzodithiophene,tetrabromoquinoxaline phenanthro phenazine and 3,4-propylenediothiophene.A series of tests were conducted on these polymers to research their electrochromic properties,the results showed that the characteristics of polymers can be tuned by adjusting the ratio of donor to acceptor and the polymers have high thermodynamic stability and more than two color changes.The optical band gaps about PTPE-1 to PTPE-3 are less than 1.85 eV,and the optical contrast and dynamic stability of PTPE-3 are particularly excellent,the optical contrast of PIPE-1 and PIPE-2 in visible and near infrared regions are higher than 40% and 60%,respectively.The response time of PIPE-2 in near infrared region is only 0.35 s.The optical band gaps are1.98 eV for PBPE-1,2.01eV for PBPE-2 and 2.03 eV for PBPE-3,the coloration efficiency of PBPE-3 at 504 nm and 1500 nm are as high as 513 cm²·C^-1 and 475 cm²·C^-1,respectively.In Chapter 5,the polymers PBBE-1,PBBE-2 and PBBE-3 with yellowish green in neutral state were synthesized by using benzenediboronic acid dipinacol ester,brominated butyl-triphenylamine and 3,4-propenyldioxythiophene.The response time are 0.57s for PBBE-1 at 365 nm,0.32 s and 0.30 s for PBBE-2 at 435 nm and 1200 nm,respectively,the optical contrast of PBBE-3 at 1550 nm is as high as 89.30%.Such rapid response time and high coloration efficiency will become excellent candidates in the field of electrochromism.