天然氨基酸水溶液中聚吡咯的电化学合成及其表征

报道了各种天然α-氨基酸水溶液中电化学聚合吡咯获得氨基酸掺杂的聚吡咯.实验表明吡咯在酸性氨基酸电解质中的氧化聚合电位较低,速度较快;而在碱性氨基酸水溶液中几乎无法进行电化学聚合.在电化学聚合过程中,氨基酸既作为支持电解质,又作为对离子被掺杂到聚合物中.该聚吡咯的电导率被测定为0.3～1.0 S/cm,在酸性氨基酸溶液中得到的聚合物电导率明显高于酸性较弱的氨基酸溶液中得到的聚合物,同时聚合物还具有良好的电化学活性和电化学稳定性,在-0.5 V到+0.5 V区间有一对氧化还原峰,该氧化还原峰的形状和特性在100次循环后基本保持不变.通过扫描电镜和透射电镜照片可以看出,不同种氨基酸的掺杂对聚吡咯的形貌具有影响,由于氨基酸的软模板效应,在数种氨基酸水溶液中能制得具有纳米纤维结构的聚吡咯.

ELECTROCHEMICAL SYNTHESES OF POLYPYRROLES IN NATURAL AMINO ACID AQUEOUS SOLUTIONS AND THEIR CHARACTERIZATION

Amino-acid-doped polypyrroles obtained by electrochemical polymerization of pyrrole in various natural α-amino acid aqueous solutions under the nitrogen atmosphere have been studied in this paper.The experiments show that the oxidation potential is relatively low and the polymerization rate is relatively high in acidic amino acid solutions,but the electrochemical polymerization barely occurs in alkaline solutions.In the electrolytic polymerization process,the amino acids act both as supporting electrolytes,and as dopant ions doped into the polymer,which can be proved by Raman,FTIR,and UV-Vis spectra.The electronic conductivity of polypyrrole is measured in the range of 0.3 and 1.0 S/cm,and the conductivity of the products obtained in strong amino acid is obviously higher than that obtained in weak amino acid.The polymers exhibit good electrochemical activity and stability,the cyclic voltammograms of these polymers have a pair of oxidation-reduction peaks between -0.5 V and 0.5 V,and their shape and trait of the polymers can stay stable after 100 electrochemical cycles.Different amino acids have different effects on the shape of the polypyrrole,polypyrrole with nano-fiber structure forms in some of the amino acid solutions due to the soft template effect,which can be seen from the SEM and TEM images.