Investigations on the Interfacial Tension Induced Self‐Assembly in Tuning the 2D Morphology of Polypyrrole at Water/Chloroform Interface

Abstract

Self-assembly of reactive intermediates at the interface of an immiscible liquid mixture is an emerging bottom-up approach in constructing 2D functional materials. Herein, a mechanistic investigation of the vital role of various oxidants in the self-assembly of reactive intermediates at the water/chloroform interface in pyrrole polymerization is reported. The energetics of one-electron transfer between pyrrole and the hydrated metal ions of the oxidant is rationalized successfully using density functional calculations. The electron microscopic and X-ray characterization techniques confirm the relatively uniform distribution of crystalline metal nanoparticles throughout the polymeric matrix. The predominance of the water/chloroform interface in thinning the polymeric sheets to 1.1 nm, by confining the assembly of polypyrrole (PPy) sheets as minimum as three layers, is approximated from atomic force microscopy images. The metal encapsulated PPy sheets are proved to have potential application in the electrochemical sensing of a potent biomarker, dopamine (DA). The electrochemical detection of DA with the limit of detection of 0.24 μm and their printability on a commercially available screen-printed electrode to detect an appreciable current affirm their potential for various electrochemical sensing applications.

Interfacial tension driven adsorption of MnO2 nanoparticles at the liquid/liquid interface to tailor ultra-thin polypyrrole sheets

“…35 The spontaneity of the redox reaction between the monomer and oxidant depends on the decrease in the thermodynamic Gibbs free energy (ΔG °). 24 Here, the monomer pyrrole and the oxidant KMnO 4 form an electrode couple in which the pyrrole (Py) is oxidized to a pyrrole radical cation (Py •+ ) ( pyrrole works as the anode) and KMnO 4 gets reduced to MnO 2 (KMnO 4 works as the cathode) as shown in eqn ( 1) and ( 2). From the electrochemical series, the standard reduction potentials of the pyrrole and KMnO 4 are −0.9 V and 0.595 V, respectively.…”

“…1A 3). 18,24,43 The interfacial adsorption of MnO 2 attached oligomers, or short-chain polymers, acts as the driving force for the confined 2-D growth of PPy sheets. The 2-D ordering of PPy chains and the layer-by-layer growth of π-π stacked 2-D aligned PPy chains at the water/chloroform interface resulted in PPy/MnO 2 sheets at the end of 15 hours (Fig.…”

“…24 This could be due to the highly crystalline nature of MnO 2 that subsides the diffractions caused by amorphous PPy. 24 The peaks at 2θ = 13.461°, 20.874°, 28.829°, 37.507°, 62.818°, 69.688°, 77.101°, and 84.152°can be attributed to the Bragg diffractions caused by the (110), ( 200), (310), ( 211), ( 521), ( 541), ( 402) and (512) planes, respectively. 32,54,60 The XRD spectrum (Fig.…”

“…22 The preferential adsorption of NPattached oligomers at the interface and subsequent product confinement led to the formation of ultra-thin films with attached nano-sized particles. [23][24][25] Thus, a unique one-pot synthesis of polymer thin films with encapsulated NPs is an effective strategy to confine NPs at the L/L interface or tune the polymer morphology to ultra-thin sheets.…”

“…1,27 The nanostructure tuning to ultra-thin 2-D films at the L/L interface is impelled by the self-organization of reactive mole-cular species at the interface of two immiscible liquids. [24][25][26] The conventional methods are tedious to synthesize thin films due to the material characteristics (insolubility, dispersibility, transparency, and homogeneity) or stringent deposition conditions. 22 The L/L interface-assisted method ensures the facile deposition of thin films of single or multi-component materials that are effortlessly transferred to any substrates ( plastic or flexible substrates).…”