Electrosynthesis And Properties Of Boronic Acid Functionalized Free-standing Conducting Polymer Films

Conducting polymers(CPs)continuous to attract extensive attention in fundamental research and practical applications due to their electrical and electrochemical properties similar to those of traditional semiconductors and metals.CPs are good candidates for application in domains of electronics,optoelectronics,sensors and energy equipment because they possess excellent characteristics including mild synthesis conditions,chemical structural diversity,adjustable conductivity and flexible structure.Boronic acid group is capable to form borate ester combine with dialcohols and react with Lewis base to form anions and fluoride ions,which make it a research hotspot in optical and electrochemical sensors and biomedical fields.In addition,as an electron-withdrawing group,organoboron substituents can regulate the energy gap of CPs,making boronic acid functionalized CPs one of promising candidates for application in the field of photoelectricity.In this thesis,three kinds of boronic acid group functionalized free-standing CPs films were prepared by electrosynthesis,and their electrochemical behavior,structural morphology,thermal stability,electrical conductivity and polymerization system of monomer were measured and analyzed.(1)A free-standing poly(5-indolylboronic acid)film with electrical conductivity of 0.09 S m^-1 was successfully electrosynthesized in the mixed system of boron trifluoride diethyl ether(BFEE),ACN and Bu₄NBF₄(0.1 M).The onset oxidation potential and polymerization system of 5-indolylboronic acid were optimized,and the initial oxidation potential of 5-indolylboronic acid was 0.75 V vs.AgCl when the BFEE content was 80%.Besides,FT-IR spectra indicated that the polymerization sites of 5-indolylboronic acid were C₂ and C₃ on the pyrrole ring.The electrochemical and thermal test results exhibited that the poly(5-indolylboronic acid)film has good electrochemical activity and high thermal stability.After 1300 K,the mass retention of the poly(5-indolylboronic acid)film is 61.4%.(2)High-quality free-standing poly(3-thiophene boronic acid)film with electrical conductivity of 0.027 S cm^-1 was successfully electrosynthesized by anodic oxidation method in the mixed system of BFEE,ACN and Bu₄NBF₄(0.1 M).The initial oxidation potential of 3-thiophene boronic acid was only 1.27 V when the BFEE content was 50%.FT-IR,UV-vis spectra and morphology of as-prepared polymer were analyzed in detail.In addition,the power factor of poly(3-thiophene boronic acid)was 0.0422?W m^-1 K^-2,which is much higher than that of polythiophene prepared in the same system(0.0074?W m^-1 K^-2).Introduction of boronic acid groups greatly improved the performance of polythiophene,including the thermal stability,electrical conductivity and thermoelectric performance.(3)Poly(1-naphthalene boronic acid)film with electrical conductivity of 0.03 S m^-1 was prepared successfully by anodic oxidation method in the mixed system of BFEE,CH₂Cl₂ and Bu₄NPF₆(0.1 M).The onset oxidation potential of the monomer was 1.0 V when the BFEE content was 40%.The FT-IR spectra indicated that the polymerization sites were at C₅ and C₈.The fluorescence spectra demonstrated that the poly(1-naphthalene boronic acid)was a good green emitter.Electrochemical and thermal analysis results showed that as-prepared polymer has good electrochemical stability and thermal stability.