Carboxymethyl Cellulose (CMC) as a Template for Laccase-Assisted Oxidation of Aniline.

Euijin Shim,Hye Rim Kim,Carla Silva,Jennifer Noro,Artur Cavaco-Paulo

doi:10.3389/fbioe.2020.00438

Abstract

Polyaniline (PANi) is a conducting polymer which has been subject of intensive research on the exploitation of new products and applications. The main aim of the work is the development of a conductive bacterial cellulose (BC)-based material by enzymatic-assisted polymerization of aniline. For this, we study the role of carboxymethyl cellulose (CMC) as a template for the in situ polymerization of aniline. Bacterial cellulose was used as the supporting material for the entrapment of CMC and for the in situ oxidation reactions. The amount of CMC entrapped inside BC was optimized as well as the conditions for laccase-assisted oxidation of aniline. The new oligomers were evaluated by spectrometric techniques, namely 1H NMR and MALDI-TOF, and the functionalized BC surfaces were analyzed by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and reflectance spectrophotometry. The conductivity of the developed materials was evaluated using the four-probe methodology. The oligomers obtained after reaction in the presence of CMC as template display a similar structure as when the reaction is conducted only in BC. Though, after oxidation in the presence of this template, the amount of oligomers entrapped inside BC/CMC is considerably higher conferring to the material greater electrical conductivity and coloration. The use of CMC as a template for aniline oxidation on BC seems to be a promising and cheap strategy to improve the yield of functionalization and increment the properties of the materials, namely electrical conductivity and coloration.

Highlights

Conductive materials have been gaining scientific attention due to the increasing need for new technologies for the exploitation of electronic sensor devices, energy-storage, and intelligent clothing (Sapurina and Shishov, 2012)
From the results presented it is perceptible that when carboxymethyl cellulose (CMC) is entrapped inside bacterial cellulose (BC) and used as polymerization template, the amount of polymer inside the BC network is higher than when the polymerization is conducted using BC without CMC
We study the role of CMC as a template for the enzymatic polymerization of aniline inside BC membranes

Summary

Introduction

Conductive materials have been gaining scientific attention due to the increasing need for new technologies for the exploitation of electronic sensor devices, energy-storage, and intelligent clothing (Sapurina and Shishov, 2012). The use of templates, like sulfonated polystyrene as sodium salt (SPS), the calcium salt of ligninosulfonate, micelles composed by sodium dodecylbenzenesulfonate (SDBS), or vesicles made-up of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) have been described as favoring the polymerization of aniline (Walde et al, 2019). The templates, due to a localization of the reaction in their vicinity, direct the regioselectivity of the monomer coupling reaction, favoring para-over ortho-coupling of oxidized aniline These compounds have dopant action (counter ions), which balance the positive charge on the PANi, thereby stabilizing the PANi-Emeraldine salt structure, crucial for electrical conductivity. The template works by forming polymer– polymer complexes which are stabilized via non-covalent binding forces among hydrogen bonds, electrostatic and hydrophobic interactions during polymerization (Kim et al, 2004; Yue et al, 2016)

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