Synthesis and Characterization of Hollow-Sphered Poly(N-methyaniline) for Enhanced Electrical Conductivity Based on the Anionic Surfactant Templates and Doping.

Chatrawee Direksilp,Anuvat Sirivat

doi:10.3390/polym12051023

Chatrawee Direksilp, Anuvat Sirivat

Open Access

https://doi.org/10.3390/polym12051023

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Journal: Polymers	Publication Date: May 1, 2020
Citations: 19	License type: CC BY 4.0

Affiliation: Chulalongkorn University, Petromat

Abstract

Poly(N-methylaniline) (PNMA) is a polyaniline derivative with a methyl substituent on the nitrogen atom. PNMA is of interest owing to its higher solubility in organic solvents when compared to the unsubstituted polyaniline. However, the electrical conductivity of polyaniline derivatives suffers from chemical substitution. PNMA was synthesized via emulsion polymerization using three different anionic surfactants, namely sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and dioctyl sodium sulfosuccinate (AOT). The effects of surfactant structures and concentrations on electrical conductivity, doping level, crystallinity, morphology, and thermal stability were investigated. The re-doping step using perchloric acid (HClO4) as a dopant was sequentially proceeded to enhance electrical conductivity. PNMA synthesized in SDBS at five times its critical micelle concentration (CMC) demonstrated the highest electrical conductivity, doping level, and thermal stability among all surfactants at identical concentrations. Scanning electron microscopy (SEM) images revealed that the PNMA particle shapes and sizes critically depended on the surfactant types and concentrations, and the doping mole ratios in the re-doping step. The highest electrical conductivity of 109.84 ± 20.44 S cm−1 and a doping level of 52.45% were attained at the doping mole ratio of 50:1.

Highlights

Micro- and nanostructured conductive polymers have been of interest in nanoscience and nanotechnology
An acidic molecule in an acidic solution and a surfactant were simultaneously utilized in the PNMA synthesis as a dopant and a template, respectively
The obtained particle shapes and sizes were strongly dependent on surfactant structures and concentrations

Summary

Introduction

Micro- and nanostructured conductive polymers have been of interest in nanoscience and nanotechnology. The unique properties from the nanoscale, namely the large surface area, high electrical conductivity, and light weight when compared to bulk conductive polymers, are attractive for nanoelectronics and nanodevices [1,2], chemical sensors and biosensors [3,4], energy conservation and storage (batteries, supercapacitors, photovoltaics, fuel cells, solar cells) [5,6], electromagnetic interference shielding [7], biomedical devices [8,9], and electroactive devices [10]. A simple, cheap, and powerful process to produce nanostructured polymers is the soft-template method including micro-/mini-emulsion polymerization, reversed micro-emulsion polymerization, and layer-by-layer self-assembly based on the self-assembly of surfactants. The soft-template method does not require elaborate post-treatment process to remove the template [2,5,12].

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