Fe2+/Fe3+ REDOX COUPLE-DOPED POLYSILOXANE COMPOSITES AS CONDUCTIVE POLYMER FILMS
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Date
2025-12-04
Authors
Asmaa, Salim
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Publisher
An-Najah National University
Abstract
This study investigated the development of a novel polymer material combining polymer flexibility with electrical conductivity by doping non-conductive polysiloxane with highly efficient Faraday-active iron (Fe²⁺/Fe³⁺) pairs. Despite the high thermal and chemical stability potential of polysiloxane, there is limited electrical conductivity and the application of iron ions has not been studied.
This study aimed to prepare iron-doped polysiloxane thin films and investigate their structural, electrical, and chemical properties using FTIR, UV-Vis, TGA, and AFM techniques, along with J-V and VNA conductivity measurements and electrochemical analyses (CV and EIS).
The iron integration in the polymer network was confirmed by the results, and the electronic transition and absorption bands that correspond to Fe²⁺/Fe³⁺ interaction with Si–O–Si groups were observed. Thermal and surface studies verified that minor structural modifications were observed but that the materials remained stable. Quantitatively, the conductivity depends on the polymer concentration, the redox couple concentration, the film thickness, and annealing temperature. Optimal performance was achieved with 0.01 g polymer, 2.0 g FeCl₂ plus 2.54 g FeCl₃; a final thickness of 783 nm; and annealing at 150°C for one hour.
The optimal sample’s conductivity reached a value of 7.2 × 10^(-5) S/cm, which is hundreds of times higher than the pure polysiloxane. CV and EIS proved that the film contained an efficient and stable redox system, while a significant reduction happened in the resistance against charge transfer. This demonstrates that the conductivity mechanism is dependent on electron hopping between Fe²⁺ and Fe³⁺. Additionally, the chemical stability tests (after 6 months) were consistent with the stability of the main polymer bonds and there was no degradation of the structural structure.
This research paves a foundation for the construction of semiconducting polymer materials that may be exploited for sensors, flexible electronics, smart membranes and electrochemical applications. Other redox systems (Co, Mn, Ni) should be investigated or iron and carbon materials or MOFs can be used to enhance future performance.