Controlled Synthesis Of The Helical Structure Of Chiral Conductive Polyaniline And Its Derivatives

Synthesis of structures with controlled helicity has always been a challenge in the field of polymer.Chiral polyaniline(PANI)as a conducting polymer has potential applications as chiral catalysts,chiral electrodes,chiral sensors,chiral stationary phases and so on.In this paper,we used aniline and p-phenylenediamine or N-phenyl-p-phenylenediamine as raw materials to synthesize different kinds of aniline oligomers,and the structure of synthetic aniline oligomers were characterized by Fourier infrared spectrometry and Nuclear magnetic resonance at first.Then chiral polyaniline and its derivatives were synthesized with the chemical oxidation method by introducing methyl,ethyl,methoxy and chlorine groups to aniline monomer,D-camphorsulfonic acid(D-CSA)as chiral induction agent and doping agent,using different kinds of aniline oligomers as auxiliary,ammonium persulfate(APS)as the initiator and oxidant.Then tailoring of helical conformation of substituted polyanilines by controlling steric hindrance.We explored the types of substituents,copolymerization process,the concentration of monomers and polymerization temperature,the types and amount of oligomer,the types and amount of adding inorganic salts to regulate helical structure of polyaniline and polyaniline derivatives.Finally,the formation mechanism of helical structure of the polyaniline and its derivatives were discussed in detail.In this paper,Fourier infrared spectrometry(FT-IR)is used to characterize the structure of polymer.Circular dichroism spetroscopy(CD)and UV-vis spectrophotometer(UV-vis)are used to study the optical activity and helical structure of polyaniline and its derivatives.The results suggest that the introduction of substituent not only causes optical activity changing,but also changes the conformation from "extended coil" to "compact coil" conformation.The results of characterization of chiral polyaniline and its derivatives indicate that we can realize the controllable synthesis of helical structure of of polyaniline and its derivatives by regulating the molar ratio of aniline and its derivatives,the concentration of monomers and polymerization temperature,the types and amount of oligomer,the types and amount of adding inorganic salts.In addition,the theoretical simulation results show that the position of the substituents can also regulate the helical conformation of polymer.Thermal stability of the alkyl substituted polyaniline by TGA is lower than PANI.It is found that morphology of chiral polyaniline and its derivatives show fibrous,but the fiber length of the derivatives is shorter than PANI and unevenly disperses by SEM.The conductivity of polyaniline derivatives by digital four-probe tester methods is characterized lower than PANI,but the solubility of polyaniline derivatives is improved in common organic solvents.