Synthesis And Electrochromic Properties Of Conjugated Polymers Based On 3,4-Propylenedioxythiophene Or Quinoxaline Units

Since it was discovered,conductive polymers have been widely used in smart windows,light-emitting diodes,energy-saving materials,and optical displays because of their good photoelectric properties,various color changes,and strong plasticity.At the same time,people have been trying hard to expect to develop polymers with better performance.In this dissertation,the monomers based propylenedioxythiophene and quinoxaline were synthesized by modifying the molecular structure at the first step.Then a variety of conjugated polymers with excellent properties were synthesized by chemical polymerization and a series of tests containing electrochemical properties and chemical properties based these polymers were measured.In Chapter 2,we selected propylenedioxythiophene and thiophene as the acceptor units and benzotriazole as the acceptor unit.Then three polymers were synthesized by chemical polymerization,named PTBE-1,PTBE-2 and PTBE-3,respectively.All three polymers can convert from red neutral to light gray oxidation states.In the dynamic performance test,the three polymers showed a large optical contrast both in the visible and near-infrared r_egions.In particular,the contrast of PTBE-2 and PTBE-3 in the visible region can reached more than 40%,this is a considerable value among the visible region.Combined with their lower response time and greater coloring efficiency,it can be expected that they can have a wide range of applications in the field of electrochromic materials.In Chapter 3,we selected thiophene and carbazole as the donor units,benzotriazole and quinoxaline as the acceptor units,successfully synthesized three polymers:PTBCQ-1,PTBCQ-2,and PTBCQ-3.When the film changes from a neutral state to an oxidized state,the color of PTBCQ-1 changed from maroon to dark gray,PTBCQ-2 changed from crow cyan to light slate gray,and PTBCQ-3 changed from brick red to dark gray.In the kinetic test,all the three polymers exhibited excellent optical contrast and large coloring efficiency in the near-infrared region and maybe applied in the near-infrared electrochromic field.In Chapter 4,we selected propylenedioxythiophene,methoxythiophene and thiophene as the donor units and quinoxaline as the acceptor unit to synthesize three polymers:PTQET-1,PTQET-2.,PTQET-3.All the three polymers exhibited lower optical band gap values?1.51 eV,1.42 eV and 1.29 eV,respectively?,and showed a rapid color change between neutral and oxidized states?PTQET-1 changed from ink gray to floralwhite.PTQET-2 changed from pale black to navy blue,PTQET-3 changed from dark gray to brick red?.The three polymers exhibited high optical contrast and coloring efficiency in the near-infrared region.It is worth noting that PTQET-2 had a very low response time?less than 1 s?both in the visible and near-infrared regions,and can maintained a stable optical contrast under different pulse times,which undoubtedly makes it popular in future applications.In Chapter 5,we prepared a black copolymer PTBEID by the copolymerization of a red polymer PTBE-3 and another blue polymer PTID.The polymer can achieve rapid conversion from neutral black to oxidized blue-gray.PTBEID exhibited high optical contrast and coloring efficiency both in the visible and near-infrared regions,and simultaneously showed a low response time.All the results show that PTBEOD can be an excellent electrochromic material.