Processable polyaniline suspensions through in situ polymerization onto nanocellulose

Synthesis and Characterization of Polyaniline Emeraldine Salt (PANI-ES) Colloids Using Potato Starch as a Stabilizer to Enhance the Physicochemical Properties and Processability

Conductive polymers, such as polyaniline (PANI), have interesting applications, ranging from flexible electronics, energy storage devices, sensors, antistatic or anticorrosion coatings, etc. However, the full exploitation of conductive polymers still poses a challenge due to their low processability. The use of compatible stabilizers to obtain dispersible and stable colloids is among the possible solutions to overcome such drawbacks. In this work, potato starch was used as a steric stabilizer for the preparation of colloidal polyaniline (emeraldine salt, ES)/starch composites by exploiting the oxidative polymerization of aniline in aqueous solutions with various starch-to-aniline ratios. The polyaniline/starch bio-composites were subjected to structural, spectroscopic, thermal, morphological, and electrochemical analyses. The samples were then tested for their dispersibility/solubility in a range of organic solvents. The results demonstrated the formation of PANI/starch biocomposites with a smaller average size than starch particles, showing improved aqueous dispersion and enhanced solubility in organic solvents. With respect to previously reported PANI-EB (emeraldine base)/starch composites, the novel colloids displayed a lower overall crystallinity, but the conductive nature of PANI-ES enhanced its electrochemical properties, resulting in richer redox chemistry, particularly evident in its oxidation behavior, as observed through cyclic voltammetry. Finally, as proof of the improved processability, the colloids were successfully integrated into a thin polyether sulfone (PES) membrane.

Synthesis and characterization of polyaniline-based composites using cellulose nanocrystals as biological templates

Polyaniline (PANI) is considered as an ideal electrode material due to its remarkable Faradaic activity, exceptional conductivity, and ease of processing. However, the agglomeration and poor cycling stability of PANI largely limit its practical utilization in energy storage devices. To address these challenges, PANI was synthesized via a facile one-pot, two-step process using cellulose nanocrystals (CNCs) as bio-templates in this work. Zeta potential and particle size measurements revealed that the CNC template could impart improved dispersion stability to the synthesized PANI, which exhibited a decrease in average particle size from 1100 nm to 300 nm as a function of 10 % CNCs. Furthermore, the effect of CNC loadings on the performance of PANI was systematically investigated. The results showed that the specific capacitance of PANI/CNC increased from 102.52 F·g-1 to 138.12 F·g-1 with the CNC loading increase from 0 to 10 wt%. Particularly, the PANI/CNC composite film with a 1:9 ratio (C-P-10 %) demonstrated a capacity retention of 84.45 % after 6000 cycles and an outstanding conductivity of 526 S·m-1. This work generally offers an effective solution for the preparation of high-performance PANI-based composites, which might hold great promise in energy storage device applications.

Pickering emulsions as an effective route for the preparation of bioactive composites: A study of nanocellulose/polyaniline particles with immunomodulatory effect

Several studies have reported on application of cellulose particles for stabilizing Pickering emulsions (PE). Here we employ an original approach that involves using these particles as a part of advanced composite colloids made of conducting polymer polyaniline (PANI) and cellulose nanocrystals (CNC) or nanofibrils (CNF). PANI/cellulose particles were prepared using oxidative polymerization of aniline in situ in the presence of CNC or CNF. The type and amount of celluloses (CNC vs CNF) and concentration of precursors (aniline monomer and oxidant) used in the reaction determined properties of the colloidal particles, such as size, morphology and content of PANI. The particles demonstrated intriguing biological characteristics, including no cytotoxicity, antibacterial activity against Staphylococcus aureus and Escherichia coli, antioxidant activity and related immunomodulatory activity. For the first time, such composites were used to successfully stabilize oil-in-water PE with undecane or capric/caprylic triglyceride oils. The properties of the emulsions were determined by the PANI/cellulose particles and oil used. The key finding of the study is the demonstrated ability of PANI/cellulose particles to stabilize PE, as well as the excellent antioxidant activity and ROS scavenging action originating from PANI presence, indicating potential of such systems for use in biomedicine, particularly for wound healing.

Synthesis, Properties, Applications, and Future Prospective of Cellulose Nanocrystals

The exploration of nanocellulose has been aided by rapid nanotechnology and material science breakthroughs, resulting in their emergence as desired biomaterials. Nanocellulose has been thoroughly studied in various disciplines, including renewable energy, electronics, environment, food production, biomedicine, healthcare, and so on. Cellulose nanocrystal (CNC) is a part of the organic crystallization of macromolecular compounds found in bacteria's capsular polysaccharides and plant fibers. Owing to numerous reactive chemical groups on its surface, physical adsorption, surface grating, and chemical vapor deposition can all be used to increase its performance, which is the key reason for its wide range of applications. Cellulose nanocrystals (CNCs) have much potential as suitable matrices and advanced materials, and they have been utilized so far, both in terms of modifying and inventing uses for them. This work reviews CNC's synthesis, properties and various industrial applications. This review has also discussed the widespread applications of CNC as sensor, acoustic insulator, and fire retardant material.

Harnessing Nature's Ingenuity: A Comprehensive Exploration of Nanocellulose from Production to Cutting-Edge Applications in Engineering and Sciences

Primary material supply is the heart of engineering and sciences. The depletion of natural resources and an increase in the human population by a billion in 13 to 15 years pose a critical concern regarding the sustainability of these materials; therefore, functionalizing renewable materials, such as nanocellulose, by possibly exploiting their properties for various practical applications, has been undertaken worldwide. Nanocellulose has emerged as a dominant green natural material with attractive and tailorable physicochemical properties, is renewable and sustainable, and shows biocompatibility and tunable surface properties. Nanocellulose is derived from cellulose, the most abundant polymer in nature with the remarkable properties of nanomaterials. This article provides a comprehensive overview of the methods used for nanocellulose preparation, structure-property and structure-property correlations, and the application of nanocellulose and its nanocomposite materials. This article differentiates the classification of nanocellulose, provides a brief account of the production methods that have been developed for isolating nanocellulose, highlights a range of unique properties of nanocellulose that have been extracted from different kinds of experiments and studies, and elaborates on nanocellulose potential applications in various areas. The present review is anticipated to provide the readers with the progress and knowledge related to nanocellulose. Pushing the boundaries of nanocellulose further into cutting-edge applications will be of particular interest in the future, especially as cost-effective commercial sources of nanocellulose continue to emerge.

Development of nanocellulose fiber reinforced starch biopolymer composites: a review

In the last few years, there are rising numbers for environmental waste due to factors such as plastic based food packaging that really need to get enough attention in order to prevent the issue from becoming worse and bringing disaster to society. Thus, the uses of plastic composite materials need to be reduced and need to be replaced with materials that are natural and have low degradation to preserve nature. Based on the statistics for the global, the production of plastic has been roughly calculated for passing 400 million metric tons every year and has a high probability of approaching the value of 500 million metric tons at the year of 2025 and this issue needs to be counteracted as soon as possible. Due to that, the increasing number for recent development of natural biopolymer, as an example starch, has been investigated as the substitution for the non-biodegradable biopolymer. Besides, among all biodegradable polymers, starch has been considered as promising substitution polymer due to its renewability, easy availability, and biodegradability. Apart from that, by the reinforcement from the nanocellulose, starch fiber has an increasing in terms of mechanical, barrier and thermal properties. In this review paper, we will be discussing the up-to-date development of nanocellulose fiber reinforced starch biopolymer composites throughout this century.

Mechanically Enhanced Nanocrystalline Cellulose/Reduced Graphene Oxide/Polyethylene Glycol Electrically Conductive Composite Film

Traditional conductive materials do not meet the increasing requirements of electronic products because of such materials' high rigidity, poor flexibility, and slow biodegradation after disposal. Preparing flexible conductive materials with excellent mechanical properties is an active area of research. The key to flexible conductive materials lies in the combination of the polymer matrix and conductive components. This combination can be achieved by making a film of renewable nano-microcrystalline cellulose (NCC) and reduced graphene oxide (rGO) with excellent electrical conductivity-by simple filtration and introducing polyethylene glycol (PEG) to enhance the functionality of the composite film. Graphene imparted conductivity to the composite film, which reached 5.67 S·m^-1. A reinforced NCC/rGO/PEG-4 composite film with a thickness of only 21 μm exhibited a tensile strength of 30.56 MPa, which was 83% higher than that of the sample without PEG (16.71 MPa), and toughness of 727.18 kJ·m^-3, which was about 132% higher than that of the control sample (NCC/rGO, 313.86 kJ·m^-3). This ultra-thin conductive composite film-which can be prepared simply, consists of environmentally sustainable and biodegradable raw materials, and exhibits excellent mechanical properties-has substantial potential for applications in e.g., flexible electronic wearable devices, electrodes, and capacitors.

Physicochemical Properties and Atomic-Scale Interactions in Polyaniline (Emeraldine Base)/Starch Bio-Based Composites: Experimental and Computational Investigations

The processability of conductive polymers still represents a challenge. The use of potato starch as a steric stabilizer for the preparation of stable dispersions of polyaniline (emeraldine base, EB) is described in this paper. Biocomposites are obtained by oxidative polymerization of aniline in aqueous solutions containing different ratios of aniline and starch (% w/w). PANI-EB/Starch biocomposites are subjected to structural analysis (UV-Visible, RAMAN, ATR, XRD), thermal analysis (TGA, DSC), morphological analysis (SEM, Laser Granulometry), and electrochemical analysis using cyclic voltammetry. The samples were also tested for their solubility using various organic solvents. The results showed that, with respect to starch particles, PANI/starch biocomposites exhibit an overall decrease in particles size, which improves both their aqueous dispersion and solubility in organic solvents. Although X-ray diffraction and DSC analyses indicated a loss of crystallinity in biocomposites, the cyclic voltammetry tests revealed that all PANI-EB/Starch biocomposites possess improved redox exchange properties. Finally, the weak interactions at the atomic-level interactions between amylopectin–aniline and amylopectin–PANI were disclosed by the computational studies using DFT, COSMO-RS, and AIM methods.

Electrospinning of Electroconductive Water-Resistant Nanofibers of PEDOT-PSS, Cellulose Nanofibrils and PEO: Fabrication, Characterization, and Cytocompatibility

Electrically conductive composite nanofibers were fabricated using poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT-PSS) and cellulose nanofibrils (CNFs) via the electrospinning technique. Poly(ethylene oxide) (PEO) was used to assist the electrospinning process, and poly(ethylene glycol) diglycidyl ether was used to induce chemical cross-linking, enabling stability of the formed fibrous mats in water. The experimental parameters regarding the electrospinning polymer dispersion and electrospinning process were carefully studied to achieve a reproducible method to obtain bead-free nanofibrous mats with high stability after water contact, with an electrical conductivity of 13 ± 5 S m^-1, thus making them suitable for bioelectrochemical applications. The morphology of the electrospun nanofibers was characterized by scanning electron microscopy, and the C/S ratio was determined with energy dispersive X-ray analysis. Cyclic voltammetric studies showed that the PEDOT-PSS/CNF/PEO composite fibers exhibited high electroactivity and high stability in water for at least two months. By infrared spectroscopy, the slightly modified fiber morphology after water contact was demonstrated to be due to dissolution of some part of the PEO in the fiber structure. The biocompatibility of the PEDOT-PSS/CNF/PEO composite fibers when used as an electroconductive substrate to immobilize microalgae and cyanobacteria in a photosynthetic bioelectrochemical cell was also demonstrated.

Electrochemical Preparation of Polyaniline- Supported Cu-CuO Core-Shell on 316L Stainless Steel Electrodes for Nonenzymatic Glucose Sensor

In this article, we reported the elaboration of a nonenzymatic glucose sensor based on the polyaniline-supported Cu-CuO core-shell structure prepared on the 316L stainless steel electrode by electrochemical methods. In the first step, polyaniline (PANI) film was electrodeposited on the 316L substrate from a solution of 0.1 M aniline and 0.5 M sulfuric acid in absolute ethanol by the cyclic voltammetry (CV) method. In the second step, the copper particles were electrodeposited on the PANI film from CuCl2·2H2O 0.01 M precursor prepared in a KCl 0.1 M solution by the CV method. In the third step, Cu particles were partially oxidized to CuO by the CV method in a NaOH 0.1 M electrolyte to form a Cu-CuO core-shell structure supported on the PANI film. The as-prepared electrode (Cu-CuO/PANI/316L) was used to detect glucose in a NaOH 0.1 M solution. The Cu-CuO/PANI/316L sensor exhibited a linear range of 0.1–5 mM (R2 = 0.995) with a detection limit of 0.1 mM (S/N = 3) and high sensitivity of (25.71 mA·mM−1·cm−2). In addition, no significant interference was observed from sucrose, maltose, lactose, and ascorbic acid. The results showed that the polyaniline-supported Cu-CuO core-shell structure has the potential to be applied as an electrode material for the nonenzymatic glucose sensor.

Manipulation of Fibril Surfaces in Nanocellulose-Based Facilitated Transport Membranes for Enhanced CO2 Capture

The transition toward sustainable processing entails the use of biobased alternatives as functional materials to reduce the overall carbon footprint. Nanocellulose, due to its natural availability, biodegradability, excellent mechanical properties, tunable surface, and high aspect ratio, is attracting more and more interest as a nanoscale additive in polymeric membranes. In this work, an effective way to modify nanocellulose fibril surfaces for performance enhancement in CO₂ separation membranes has been demonstrated. The functionalization promptly triggered intrinsic property responses in favor of nanofiber dispersion and CO₂ transport. Thin composite membranes containing the modified nanofibers in water-swelling poly(vinyl alcohol) (PVA) as well as in the blend of sterically hindered polyallylamine (SHPAA) and PVA were fabricated and tested using humid gas permeation tests. Defect-free ultrathin (300 nm) hybrid selective layers containing evenly distributed nanofibers were successfully coated. The addition of nanocellulose exhibited enhanced CO₂ permeance and CO₂/N₂ selectivity compared to those of the neat PVA membranes. CO₂ permeance up to 652 GPU and a CO₂/N₂ selectivity of 41.3 with SHPAA/PVA blend were documented. Functionalization plays a categorical role in the dispersion of nanocellulose fibrils in the SHPAA/PVA blend, increasing the steric stabilization and interface compatibility with the polymer matrix. The tuned interface with PEG groups act as sites for water clusters retention and increased CO₂ solubility, thus creating fast diffusion pathways for CO₂ transport.

Nanocellulose applications in sustainable electrochemical and piezoelectric systems: A review

Recent studies advocate the use of cellulose nanomaterials (CNs) as a sustainable carbohydrate polymer in numerous innovative electronics for their quintessential features such as flexibility, low thermal expansion and self-/directed assembly within multiphase matrices. Herein, we review the contemporary advances in CN-built electrochemical systems and highlight the constructive effects of these nanoscopic entities once engineered in conductive composites, proton exchange membranes (PEMs), electrochromics, energy storage devices and piezoelectric sensors. The adopted strategies and designs are discussed in view of CN roles as copolymer, electrolyte reservoir, binder and separator. Finally, physiochemical attributes and durability of resulting architectures are compared to conventional materials and the possible challenges/solutions are delineated to realize the promising capabilities. The volume of the up-to-present literature in the field indeed implies to nanocellulose overriding importance and the presented angles perhaps shed more lights on prospect of the biosphere's most dominant biomaterial in the energy-related arena that deserve attention.

Conductive bacterial cellulose by in situ laccase polymerization of aniline

Conductive and colored bacterial cellulose (BC) was developed by entrapment of polyaniline (PANi) onto dry BC membranes. The polyaniline was produced by in situ green polymerization of aniline by Myceliophthora thermophila laccase at pH = 4, 25°C, in the presence of a mediator, 1-hydroxybenzotriazol (HBT), using two different reactors, a water bath (WB) and an ultrasonic bath (US). MALDI-TOF and 1H NMR characterization of the experiment solutions confirmed the efficient polymerization of aniline by laccase. The dried BC membranes with entrapped polyaniline showed electrical conductive behavior and strong coloration, opening novel routes for the exploitation of functionalized bacterial cellulose as a green material for technical textiles, wearables, and other applications.

A Surfactant Directed Microcrystalline Cellulose/Polyaniline Composite with Enhanced Electrochemical Properties

In this study a cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used as a soft template for in situ chemical polymerization of aniline on the surface of microcrystalline cellulose (MCC). The morphology of the wire-like and porous nanostructure of the resulting composite was highly dependent on the MCC and CTAB concentrations. The effect of the MCC and CTAB concentrations on the electrochemical and morphological properties of the polyaniline (PAni) nanocomposite was studied. Cyclic voltammograms of modified PAni/MCC/CTAB electrode displayed a high current response and the effect of scan rate on the current response confirmed a diffusion controlled process on the surface of the electrode that makes it suitable for sensor applications. The overlapping characteristic peaks of pure PAni and MCC caused peak broadening at 3263 cm^-1 in the IR spectra of PAni/MCC/CTAB nanocomposite that revealed the interaction between NH of PAni and OH group of MCC via electrostatic interactions. The addition of MCC to PAni through chemical polymerization decreased the thermal stability of composite compared to pure PAni. Lower crystallinity was observed in the XRD diffractogram, with 2 theta values of 22.8, 16.5, and 34.6 for PAni/MCC, confirming the formation of PAni on the MCC surface.

Cellulose Nanofiber-Based Polyaniline Flexible Papers as Sustainable Microwave Absorbers in the X-Band

A series of flexible, lightweight, and highly conductive cellulose nanopapers were fabricated through in situ polymerization of aniline monomer on to cellulose nanofibers with a rationale for attenuating electromagnetic radiations within 8.2-12.4 GHz (X band). The demonstrated paper exhibits good conductivity due to the formation of a continuous coating of polyaniline (PANI) over the cellulose nanofibers (CNF) during in situ polymerization, which is evident from scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The free hydroxyl groups on the surface of nanocellulose fibers promptly form intermolecular hydrogen bonding with PANI, which plays a vital role in shielding electromagnetic radiations and makes the cellulose nanopapers even more robust. These composite nanopapers exhibited an average shielding effectiveness of ca. -23 dB (>99% attenuation) at 8.2 GHz with 1 mm paper thickness. The fabricated papers exhibited an effective attenuation of electromagnetic waves by a predominant absorption mechanism (ca. 87%) rather than reflection (ca. 13%), which is highly desirable for the present-day telecommunication sector. Unlike metal-based shields, these demonstrated PANI/CNF papers have given a new platform for designing green microwave attenuators via an absorption mechanism. The prime novelty of the present study is that these robust PANI/CNF nanopapers have the ability to attenuate incoming microwave radiations to an extent that is 360% higher than the shielding effectiveness value reported in the previous literature. This makes them suitable for use in commercial electronic gadgets. This demonstrated work also opens up new avenues for using cellulose nanofibers as an effective substrate for fabricating conductive flexible papers using polyaniline. The direct current conductivity value of PANI/CNF nanopaper was 0.314 S/cm, which is one of the key requisites for the fabrication of efficient electromagnetic shields. Nevertheless, such nanopapers also open up an arena of applications such as electrodes for supercapacitors, separators for Li-S, Li-polymer batteries, and other freestanding flexible paper-based devices.

Cellulose and nanocellulose-based flexible-hybrid printed electronics and conductive composites - A review

Flexible-hybrid printed electronics (FHPE) is a rapidly growing discipline that may be described as the precise imprinting of electrically functional traces and components onto a substrate such as paper to create functional electronic devices. The mass production of low-cost devices and components such as environmental sensors, bio-sensors, actuators, lab on chip (LOCs), radio frequency identification (RFID) smart tags, light emitting diodes (LEDs), smart fabrics and labels, wallpaper, solar cells, fuel cells, and batteries are major driving factors for the industry. Using renewable and bio-friendly materials would be advantageous for both manufacturers and consumers with the increased use of (FHPE) electronics in our daily lives. This review article describes recent developments in cellulose and nanocellulose-based materials for FHPE, and the necessary developments required to propagate their use in commercial applications. The aim of these developments is to enable the creation of FHPE devices and components made almost entirely of cellulose materials.

Advanced Materials through Assembly of Nanocelluloses

There is an emerging quest for lightweight materials with excellent mechanical properties and economic production, while still being sustainable and functionalizable. They could form the basis of the future bioeconomy for energy and material efficiency. Cellulose has long been recognized as an abundant polymer. Modified celluloses were, in fact, among the first polymers used in technical applications; however, they were later replaced by petroleum-based synthetic polymers. Currently, there is a resurgence of interest to utilize renewable resources, where cellulose is foreseen to make again a major impact, this time in the development of advanced materials. This is because of its availability and properties, as well as economic and sustainable production. Among cellulose-based structures, cellulose nanofibrils and nanocrystals display nanoscale lateral dimensions and lengths ranging from nanometers to micrometers. Their excellent mechanical properties are, in part, due to their crystalline assembly via hydrogen bonds. Owing to their abundant surface hydroxyl groups, they can be easily modified with nanoparticles, (bio)polymers, inorganics, or nanocarbons to form functional fibers, films, bulk matter, and porous aerogels and foams. Here, some of the recent progress in the development of advanced materials within this rapidly growing field is reviewed.

Preparation, Characterization, and Electrochromic Properties of Nanocellulose-Based Polyaniline Nanocomposite Films

On the basis of nanocellulose obtained by acidic swelling and ultrasonication, rodlike nanocellulose/polyaniline nanocomposites with a core-shell structure have been prepared via in situ polymerization. Compared to pure polyaniline, the nanocomposites show superior film-forming properties, and the prepared nanocomposite films demonstrate excellent electrochemical and electrochromic properties in electrolyte solution. Nanocomposite films, especially the one prepared with 40% polyaniline coated nanocomposite, exhibited faster response time (1.5 s for bleaching and 1.0 s for coloring), higher optical contrast (62.9%), higher coloration efficiency (206.2 cm²/C), and more remarkable switching stability (over 500 cycles). These novel nanocellulose-based nanorod network films are promising novel electrochromic materials with excellent properties.

Polyaniline-modified nanocellulose prepared from Semantan bamboo by chemical polymerization: preparation and characterization

Polyaniline/crystalline nanocellulose (PANi/CNC) was prepared via in situ oxidative polymerization of aniline in the presence of crystalline nanocellulose from Semantan bamboo (Gigantochloa scortechinii).

Use of nanocellulose in printed electronics: a review

Since the last decade, interest in cellulose nanomaterials known as nanocellulose has been growing. Nanocellulose has various applications ranging from composite reinforcement to rheological modifiers. Recently, nanocellulose has been shown to have great potential in flexible printed electronics applications. The property of nanocellulose to form self-standing thermally stable films has been exploited for producing transparent and smooth substrates for printed electronics. However, other than substrates, the field of printed electronics involves the use of inks, various processing methods and the production of flexible electronic devices. This review aims at providing an overview of the use and potential of nanocellulose throughout the printed electronics field.

Antibacterial activity of silver nanoparticles synthesized In-situ by solution spraying onto cellulose

Spray technique was used for the adsorption of in-situ silver nanoparticles (AgNPs) onto and inside the surface of nano- and micro- fibrillar cellulose (NFC and MFC) as well as filter paper. The abundance of hydroxyl and carboxyl groups located in NFC and MFC are used to stabilize Ag ions (Ag(+)) which were then in-situ reduced to (AgNPs) by chemical or UV reduction. The surface characteristic features, elemental analysis, particle size as well as size distribution of the obtained MFC, NFC and filter paper loaded with AgNPs were characterized via field emission scanning electron microscopy connected to energy dispersive X-ray spectroscopy (FESEM- EDX) and transmission electron microscopy (TEM). The associated chemical changes after growth of AgNPs onto the cellulose substrates were assessed by fourier transform infra-red (FT-IR) while the thermal stability of such systems were investigated by thermogravimetrical analyses (TGA). The antibacterial properties of AgNPs loaded NFC, MFC and filter paper as well was investigated against Escherichia Coli. The resulted data indicate that the particle size was found to be 11 and 26nm for AgNPs nucleated on NFC and MFC-based papers respectively. The antibacterial activity of AgNPs loaded MFC exhibited higher antibacterial activity than that of AgNPs loaded NFC. Overall, the present research demonstrates facile and fast method for in-situ antibacterial AgNPs loading on cellulose substrates.

Enzymes as Green Catalysts for Precision Macromolecular Synthesis

The present article comprehensively reviews the macromolecular synthesis using enzymes as catalysts. Among the six main classes of enzymes, the three classes, oxidoreductases, transferases, and hydrolases, have been employed as catalysts for the in vitro macromolecular synthesis and modification reactions. Appropriate design of reaction including monomer and enzyme catalyst produces macromolecules with precisely controlled structure, similarly as in vivo enzymatic reactions. The reaction controls the product structure with respect to substrate selectivity, chemo-selectivity, regio-selectivity, stereoselectivity, and choro-selectivity. Oxidoreductases catalyze various oxidation polymerizations of aromatic compounds as well as vinyl polymerizations. Transferases are effective catalysts for producing polysaccharide having a variety of structure and polyesters. Hydrolases catalyzing the bond-cleaving of macromolecules in vivo, catalyze the reverse reaction for bond forming in vitro to give various polysaccharides and functionalized polyesters. The enzymatic polymerizations allowed the first in vitro synthesis of natural polysaccharides having complicated structures like cellulose, amylose, xylan, chitin, hyaluronan, and chondroitin. These polymerizations are "green" with several respects; nontoxicity of enzyme, high catalyst efficiency, selective reactions under mild conditions using green solvents and renewable starting materials, and producing minimal byproducts. Thus, the enzymatic polymerization is desirable for the environment and contributes to "green polymer chemistry" for maintaining sustainable society.

Enhancing the electrochromic response of polyaniline films by the preparation of hybrid materials based on polyaniline, chitosan and organically modified clay

Electrochromic materials based on PAni, chitosan and clay show distinct colour variation depending on the compound present in the hybrid material.

Agarose–guar gum assisted synthesis of processable polyaniline composite: morphology and electro-responsive characteristics

An electroactive, electroconducting, processable polyaniline composite is developed via agarose–guar gum assisted polymerization.