Impedimetry and microscopy of electrosynthetic poly(propylene imine)-co-polypyrrole conducting dendrimeric star copolymers

Abstract

A novel generation 2 poly(propylene imine)-co-polypyrrole conducting dendrimeric star copolymer (G2PPI-co-PPy) was synthesised electrochemically by oxidative copolymerization of pyrrole and pyrrole-functionalised dendrimer (G2PPI-2Py) in LiClO4 NMR spectra of G2PPI-2Py gave a new chemical shift at 8.1ppm for N=CH, which confirmed the incorporation of 2-pyrrole aldehyde into the PPI dendrimer structure. Strong FT-IR bands appeared at 1630cm−1 for N=C in the dendrimer moiety and at 729cm−1 for C-H at the α-position of the PPy ring. Electroanalysis of the polymer films deposited on Pt electrode indicated that G2PPI-co-PPy has a lower electrochemical charge transfer resistance (Rct) value compared to PPy. The decrease in Rct is due to the increase in the conjugation length of the polymer as a result of the linking of the highly conjugated PPy to the PPI dendrimer. Bode impedimetric analysis indicates that Pt|G2PPI-co-PPy is a semiconductor with a maximum phase angle shift of 45.3° at 100MHz. The scanning electron microscopy (SEM) image of G2PPI-co-PPy revealed conical PPy structures growing around a spherical core as predicted by the reaction mechanism for the formation of the dendritic star co-polymer.