Synthesis and Characterization of Four Random copolymers Containing Fluorene as Electron Donors and Benzotriazole, Benzothiadiazole, Pyrido[3,4-b]pyrazine as Electron Acceptors

Four copolymers, poly(fluorene-pyrido[3,4-b]pyrazine) (PFPP), poly(benzotriazole-fluorene-pyrido[3,4-b]pyrazine) (PBTFPP), poly(benzotriazole-fluorene-benzothiadiazole) (PBTFBD), poly(benzothiadiazole-fluorene-benzothiadiazole) (PBDFBD)were synthesized successfully. Afterwards, a series of characterization, including cyclic voltammetry (CV), spectroelectrochemistry, kinetics, colorimetry and thermal gravimetric analysis were carried out to fully investigate the properties of the copolymers we got. Their band gaps are 1.87 eV, 1.91 eV, 1.97 eV and 1.98 eV, respectively. From neutral state to oxidized state, PFPP changes from thistle to transparent gray, PBTFPP changes from tan to transparent gray, PBTFBD changes from sienna to lightslategray, and PBDFBD changes from rosybrown to lightgrey. The coloration efficiencies are 269.91cm 2 ·C -1 for PFPP, 177.45cm 2 ·C -1 for PBTFPP, 241.92cm 2 ·C -1 for PBTFBD, and 174.67cm 2 ·C -1 for PBDFBD in near infrared region. Except for PFPP, all the other three copolymers are stable and could be good candidates in electrochromic application.