Synthesis And Property Research Of Polyaniline Induced By Chiral Camphor Sulfonic Acid

The Chiral polyaniline is a special kind of conductive polymers, and has goodapplication prospect in electrochemical asymmetric synthesis, chiral recognition, chiralresolution and microwave absorbing etc. This paper using ammonium persulfate (APS)as the evocating agent and oxidant, using self-assembly synthesis method hassynthesized polyaniline with obvious single-helical characteristics. Fourier infraredspectrometry (FT-IR), UV-vis spectrophotometer (UV-vis), scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), circulationcurrent-voltage characters curve (CV), tafel polarization characteristic curve (TAF) andopen circuit potential curve (OCP) methods are used to characterized and analyzed thechiral polyaniline structure. The results show that: the ammonium persulfate (APS) asthe initiator and chiral camphor sulfonic acid (CSA) as inducer and doping agent,polyaniline with obvious single chiral performance can be got by polymerizing aniline.(1) Chiral polyaniline was successfully synthesized using the method ofself-assembly. Through the analysis in different CSA amount used, the APS dosage,reaction time and reaction temperature conditions have effects on the electrochemicalperformance of chiral polyaniline, to optimize the synthesis process, and explains thatwhen the dosage ratio of CSA: An: APS is1.5:1:1.2, and in ice-water bath conditionreacts about12hours of the preparation, chiral polyaniline electrode has the bestelectrochemical performance. Using UV-vis, FTIR, SEM and TEM to characterize andanalyze the structure of product, the results show that the chiral polyaniline of preparedby this method has obvious fibrous structure.(2) Using open circuit potential (OCP) method has researched and analyzed thechiral intense degree of polyaniline product. Controlling the dosage of An and APS witha molar ratio1:1, with aniline ratio of CSA/An at (1.5-2.0)/1, in ice water bath about15hours of reaction, the chiral degree and production yield rate of chiral polyaniline arekeeping relatively higher level, and the various electrochemical performance are well.When CSA usage increases, the degree of polyaniline hand is increased, but when CSAand An proportion is more than1.5, the increasing is not significant; the chiral degree ofpolyaniline firstly increases, and then there will be reduced trend with polymerizationtime, when the response time is about15hours, achieve maximum; along withincreasing the temperature of reaction system, chiral intense degree of product comes down. The results may be due to that when the CSA dosage increased, polyanilinedoped level is increased, causing to the electrochemical performance increasing, butwhen CSA amount is too large, due to that the polyaniline chain doped has been close tothe saturated state, so with the dosage increase of CSA, doping level has no obviouschange, so the electrochemical performance tends to be stable. The synthesis process ofpolyaniline can be divided into two phases, the chain growth stage and the configurationgrowth stage. Chain reaction growth stage is faster, and the configuration growth stageis relatively much slower. So when the polymerization reaction time is more than twohours, along with the growth of the polymerization time, polymerization production ratehas no big change, but chiral extent will continue to increase, but when the responsetime is too long, because the remains APS of the system makes the polyaniline mainchains over oxidized, chiral degree would be faintly reduced; When the temperature ofreacting system is high, the free radical production in the system is overmuch, easycause the annihilation of free radicals and the peroxidization of polyaniline chain, so thechiral degree of product and polymerization yield rate will also decreases.(3) Chiral polyaniline is used in recognizing the configuration of small moleculesamino acids. Through the CV, TAF and OCP tests of chiral polyaniline electrodes in leftand dextral alanine (D/L-Ala) electrolyte, the configuration recognizing ability of chiralpolyaniline has been explained. Experiments were using the (+)-and(-)-PANI electrodeas work-electrodes, D/L-Ala as electrolytes for electrochemical analysis, theexperimental results show that when the configuration of PANI and electrolyte isconsistent, chiral polyaniline electrode peak current and peak area of CV are bigger,TAF corrosion potential, polarization resistance and open circuit potential higher, andTAF corrosion current smaller. Through the analysis, the reason for this is when bothconfiguration consistent, small molecular electrolyte can dope into the PANI main chaineasily, improve the degree of doped polyaniline, and strengthen the activity of PANImain chain; when the configuration is opposite, electrolyte is hard to doped PANI, andcan’t make polyaniline activity improve. Research shows that, chiral polyaniline can beused in recognizing the configuration small chiral molecules amino acids.