Scalable and Low Cost Synthesis of Highly Conducting Polypyrrole Nanofibers Using Oil–Water Interfacial Polymerization under Constant Stirring

Abstract

In the present work, we report a low cost and scalable oil-water interfacial polymerization method to synthesize one-dimensional (1-D) highly conducting polypyrrole (PPy) nanofibers doped with p-toluenesulfonic (p-TSA) and hydrochloric (HCl) acids. Polymerization of pyrrole (monomer) has been carried out at the interface formed between the immiscible oil and aqueous water droplets under constant magnetic stirring at room temperature. Formation of smaller diameter (16-20 nm) PPy nanofibers has been confirmed from the high resolution transmission electron microscopy (HRTEM) studies, and the average diameter of p-TSA doped PPy nanofibers is found to be smaller than that of HCl doped nanofibers. The polymer chain ordering or crystallinity of both p-TSA and HCl doped PPy nanofibers have been studied with X-ray diffraction (XRD). Studies of Fourier transform infrared (FTIR) spectra suggest the presence of all the characteristic vibration bands in doped PPy nanofibers. The doping of PPy nanofibers has been confirmed from the formation of polaron and bipolaron bands in their UV-vis spectra. The optical band gap energy (E) and Urbach energy (E) for PPy nanofibers doped with p-TSA and HCl doped PPy nanofibers were determined from their UV-vis absorption spectra. The red shift of the polaron absorption band in p-TSA doped PPy nanofibers confirms a higher conjugation length of the polymer nanofiber chains than that in the HCl doped PPy nanofibers. Thermogravimetric (TGA) and derivative plots of TGA studies predict that PPy nanofibers doped with p-TSA are thermally and structurally more stable as compared to HCl doped PPy nanofibers. Current-voltage (I-V) characteristics exhibit nonlinear behavior with voltage in both p-TSA and HCl doped PPy nanofibers.

Synthesis and factor affecting on the conductivity of polypyrrole: a short review

“…The surfactant is used in a small quantity to stabilize the droplets of oil in water or water in oil 109 . Some researchers have also performed microemulsion polymerization to oil‐water (O‐W) or water‐oil (W‐O) interfacial polymerization 110,111 . In microemulsion polymerization, surfactant micelles may act as soft templates to generate polymeric particles, and the shape of micelles depends on the surfactant type and operational conditions 66 .…”

“…Surfactants with longer carbon chains reportedly produce larger nanoparticles than shorter carbon chains of surfactant molecules as they provide more inner space to enable necessary polymerization 6 . Moreover, microemulsion polymerization is found to increase the yield of PPy nanoparticles, that is, the extent of π‐conjugation along the polymer backbone and the ordered arrangement of macromolecular chains 111 . Figure 14A,B shows the pictorial diagram and flow chart of the synthesis of PPy nanofibers using microemulsion polymerization.…”

“…(A) Pictorial diagram of microemulsion polymerization of PPy, 111 reproduced by permission from ACS, and (B) flow chart of the synthesis of PPy nanofibers using microemulsion polymerization…”

Preparation and Characterization of Polymeric Microfibers of PLGA and PLGA/PPy Composite Fabricated by Solution Blow Spinning

“…The first one below 130 °C is attributed to water loss and other volatiles . The second one in the range of 130–265 °C is attributed to the elimination of dopant anions from the PPy chains . The third one above 265 °C with maximum decomposition temperature rate (Tmd) at 335 °C is attributed to thermal decomposition of degradation or decomposition of the main PPy.…”

“…[17] The second one in the range of 130-265 C is attributed to the elimination of dopant anions from the PPy chains. [34] The third one above…”