Conducting polymers X: Dielectric constant, conduction mechanism and correlation between theoretical parameters and electrical conductivity of poly (N,N′-bis-sulphinyl p-phenylenediamine-2,6-diaminipyridine) and poly (N,N′-bis-sulphinyl p-phenylenediamine-3,5-diamine-1,2,4-trizole)

Abstract

Poly (N,N′-bis-sulphinyl p-phenylenediamine-2,6-diaminipyridine) (PBSPDP) and poly (N,N′-bis-sulphinyl p-phenylenediamine-3,5-diamine-1,2,4-trizole) (PBSPDT) were synthesized by Micheal addition polymerization method using thionyl chloride and characterized by the FTIR and 1H NMR techniques. The number average molecular weight (Ṁn) of BSPDP and BSPDT were calculated using 1H NMR data and are found to be ∼3984 and 2156 g/mole, respectively. DC and AC electrical conductivities were measured at different temperatures confirming the semiconductor behaviors due to the delocalization of electrons of N, S and O atoms. The dielectric constants of the two polymers were investigated and the σAC was found 5.8 × 10−5 Ω−1 m−1 for PBSPDP and 9.62 × 10−5 Ω−1 m−1 for PBSPDT at 90 °C and applied frequency about 3 MHz. A theoretical study was used to calculate LUMO and HOMO energies. The high negative charges in the nitrogen atoms as well as the low activation energies of PBSPDT than PBSPDP were attributed the increased values of electrical conductivities. The impedance analyses suggested that the equivalent circuit of the both PBSPDP and PBSPDT can be presented by parallel RC model. The conduction mechanism for the electrical conductivity of the prepared polymers was found to be overlapping large polaron tunneling (OLPT). These polymers may be promising for applications such as electrochemical sensors with attractive features such as ease of synthesis, high sensitivity and fast response time.