Research On The Role Of Different Biomolecules In The Synthesis Of Chiral Polyaniline

The aim of this paper is to study the properties and mechanism of chiral polyaniline induced by different biological molecules which servers as chiral inducing agents.The three main aspects are showed below :(1)In dodecyl benzene sulfonic acid(DBSA)micelle system,different quantities of inactivated hemoglobin were used as chiral inducing agents to synthesize the chiral polyaniline with the ammonium persulfate(APS)as oxidant.(2)The properties of the polyaniline induced by RNA and DNA were compared and discussed through a series of characterization.We found that RNA is more favorable to get the polyaniline with good crystallinity and better thermal stability.(3)The properties of the polyaniline induced by different cyclodextrins were studied through different experiments.Based on the data,the mechanism of chiral polyaniline induced by cyclodextrin was deduced.Above all,in the synthesis of chiral polyaniline induced by hemoglobin,2mg,6mg,and 10 mg inactivated hemoglobin were used to induce the synthesis of chiral polyaniline.Results showed that the quantities of the inactivated hemoglobin had little influence on the chiral polyaniline.The circular dichroism spectroscopy presented the typical characteristic absorption peaks of chiral polyaniline and the intensity of absorption peak raised with the increasing quantities of inactivated hemoglobin.The Fourier transform infrared spectroscopy showed that the inactivated hemoglobin was successfully doped into the chiral polyaniline.In addition,the chiral properties of the chiral polyaniline after the dedoped and redoped process were observed by circular dichroism spectroscopy,which showed that the chiral polyaniline induced by the inactivatied hemoglobin preserved more stable chiral structure.The shape of the polyaniline was observed through the Field Emission Scanning Electron Microscopy(FESEM)which showed that the chiral polyaniline synthesized in the presence of different quantities of inactivated hemoglobin had similar nanofibrous structure,and with the increasing of the inactivated hemoglobin quantities,the diameter of the fibers became smaller and smaller.Further more,the polyaniline was characterized by UV-Vis absorption spectroscopy(UV-vis),thermogravimetric analysis(TGA)and X-ray diffraction analysis(XRD).R esults showed that the product had good thermal stability,electrical conductivity and crystal structure.More over,the circular dichroism spectroscopy of the chiral polyaniline induced by RNA and DNA was compared.It showed that the characteristic absorption peaksof chiral polyaniline apperaed at 460 nm as expected.It was known to us that compared with RNA,DNA has a double helix structure.Our experiments proved that the double helix was not necessary to the synthesis of chiral polyaniline.We also found that the pH value had a great influence on the chirality of polyaniline induced by RNA.However the opposite result was achieved for DNA.In addition,it was found that the content of both RNA and DNA little influence on the chirality of the polyaniline.Elemental analysis,TGA and XRD also indicated that RNA was more suitable to be doped into polyaniline with good thermal stability and high crystallinity.Finally,the properties and mechanism of polyaniline induced by different cyclodextrins were studied.We found that the cyclodextrins can induce the synthesis of chiral polyaniline successfully in DBSA micellar system.By the optimization of reaction conditions,we can found that the pH value,the concentration of cyclodextrin and the concentration of aniline affected the reaction.Results also showed that the variety of cyclodextrins had great influence on the chirality.It can be seen from the chart that,the polyaniline induced by hydroxypropyl beta-Cyclodextrin presented the greatest chiral intensity.Compared to beta-Cyclodextrin,there was a negative peak at620 nm from the CD spectra of modified beta-cyclodextrin-PANI.It was deduced that the steric hindrance of the substituent on cyclodextrin reduced the binding point of the cyclodextrin to aniline and the polymer,which resulted the difference of optical activity.SEM showed that the chiral conductive polyaniline synthesized in the presence of different cyclodextrins had a nanofiber structure with a diameter of15-30 nm and a length of about 690 nm.