tailieunhanh - Fourier transforms infrared study on the role of nickel-nanoclusters incorporated in polyaniline films having structure of layer by layer

Fourier transform infrared (FTIR) studies showed the changes in a relative intensity of stretching vibrations of the PANI and PANI-Ni films, in a band of 1480 and 1590 cm-1 , as well as those in a band of 1200 and 1350 cm-1 , and evidenced the conversion of quinoid form of PANI to bipolaron structure, and finally to the more delocalized polaronic sites during protonation. This also shows that nickel-nanoclusters play a role as a source supplying protons to promote the protonation, giving a change in population of quinoid and aromatic forms of PANI, and increasing a number of NH bond. By the promoted protonation, the pernigraniline base and emeraldine base that were formed during electrosynthesis will be transformed into emeraldine salt forms having NH2 + groups breaking the coupling between the P-electrons of nitrogen, and making new positive sites. This may make advantages for the. | Journal of Chemistry Vol. 44 1 P. 128 -132 2006 FOURIER TRANSFORMS INFRARED STUDy ON THE ROLE OF NICKEL-NANOCLUSTERS INCORPORATED IN POLyANILINE FILMS HAVING STRUCTURE OF LAyER By LAyER Received 26 July 2005 TRAN TRUNG Department of Electrochemistry Faculty of Chemical Technology HUT summary Fourier transform infrared FTIR studies showed the changes in a relative intensity of stretching vibrations of the PANI and PANI-Ni films in a band of 1480 and 1590 cm1 as well as those in a band of 1200 and 1350 cm1 and evidenced the conversion of quinoid form of PANI to bipolaron structure and finally to the more delocalized polaronic sites during protonation. This also shows that nickel-nanoclusters play a role as a source supplying protons to promote the protonation giving a change in population of quinoid and aromatic forms of PANI and increasing a number of NH bond. By the promoted protonation the pernigraniline base and emeraldine base that were formed during electrosynthesis will be transformed into emeraldine salt forms having NH2 groups breaking the coupling between the P-electrons of nitrogen and making new positive sites. This may make advantages for the shuttling of electrons between polaronic sites consisting of C-N and C-N . Two processes on which the conversion of quinoid-to-aromatic form of PANI can be done are proposed as follows i- during the one-step process the conversion occurs simultaneously in the coupling several segments of the same kind of PANI ii- meanwhile the two-step process the conversion and the coupling occur alternatively. Key words FTIR PANI Ni-nanoclusters conversion protonation. I - INTRODUCTION So far polyaniline PANI is still one of the most widely studied organic conducting polymers because an important concern of practical applications of PANI is the strongly dependence of its conductivity on the synthesis approach and its parameters nature of electrolyte and of dopants etc. This gives a number of various approaches to prepare a lot of