Clay/Conductive Polymer Nanocomposites

This chapter describes the main strategies for designing clay nanocomposites of the most investigated inherently conductive polymers, namely, polypyrrole, polyaniline, and polythiophenes including poly(3,4-ethylenedioxythiophene) polystyrene sulfonate. It is shown that premodification of clays is an essential step to successful intercalation or exfoliation by conductive polymers. Toward this end, surfactants, reactive diazonium, and silanes permit the preparation of adhesive clay sheets for the conductive polymers once polymerization is triggered. Exfoliated nanocomposites usually exhibit superior properties compared to intercalated ones. Through selected applications (e.g., conductive fillers, catalysts, sensors, ultracapacitors), it is clear that research on clay–conductive polymer nanocomposites will continue to grow because these materials combine the best of two worlds: low-cost abundant minerals with remarkable nanostructural properties and nanostructuring abilities on the one hand and ease of synthesis, reactivity, and electrical conductivity of conjugated polymers on the other hand.Scopu

Synthesis and structural characterization of a new macrocyclic polysiloxane-immobilized ligand system

A new porous solid macrocyclic 1,4,7,11,14-pentaazapentadecane-3,15-dione polysiloxane ligand system of the general formula P–(CH2)3–C11H22O2N5 (where P represents [Si–O] n siloxane network) has been prepared by the reaction of polysiloxane-immobilized iminobis(N-(2-aminoethyl)acetamide) with 1,3-dibromopropane. The FTIR and XPS results confirm the introduction of the macrocyclic functional ligand group into the polysiloxane network. The new macrocyclic polysiloxane ligand system exhibits high potential for the uptake of metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+)

Data on the fabrication of hybrid calix [4]arene-modified natural bentonite clay for efficient selective removal of toxic metals from wastewater at room temperature

Fresh water resources on the earth are less than 0.2%; meanwhile, around 80% of the freshwater is consumed daily in agriculture, industries, and household activities [1–2]. There is an essential need to develop efficient adsorbents for wastewater treatment [1–6], in this regards, hereafter we present the rationale synthesis and characterization of hybrid natural bentonite clay modified with Calix [4] arene (denoted as B-S-Calix) as efficient adsorbents for toxic metals from wastewater. This is driven by the facile photo-radical thiol-yne addition among the thiolated clay and an alkynylated calix[4]arene. The morphology, surface modifications, and Thermal degradation of B, B-S, and B-S-Calix were investigated using TEM, FTIR, and TGA techniques. The adsorption performance of B, BS and B-S-Calix towards toxic metals including cadmium (II) ion [Cd (II)], zinc (II) ion [Zn(II)], lead(II) ion [Pb(II)], strontium(II) ion [Sr (II)], cobalt(II) ion [Co (II)], copper(II) ion [Cu(II)], and mercury (II) ion [Hg(II)] from wastewater were benchmarked 25 °C. These data are related to the article entitled “hybrid Clay/Calix[4]arene Calix[4]arene-clicked clay through thiol-yne addition for the molecular recognition and removal of Cd(II) from wastewater’’ [7]

Rational synthesis, characterization, and application of environmentally friendly (polymer–carbon dot) hybrid composite film for fast and efficient UV-assisted Cd²⁺ removal from water

Background: Carbon dots (CDs) are of particular interest in numerous applications. However, their efficiency for heavy metal removal from wastewater was not yet reported. Herein, we rationally synthesized CDs from petroleum coke waste via hydrothermal treatment in the presence of ammonia. Results: This drove the formation of outstanding photoluminescent, water-soluble, biocompatible, and high yield of monodispersed sub-5 nm CDs. The CDs are co-doped with high 10% of N and 0.2% of S. The as-prepared CDs possess unprecedented photoluminescent properties over broad pH range making these dots unique efficient pH sensor. Conclusions: Chitosan (CH)–CDs hybrid hydrogel nanocomposite film was further prepared as a platform membrane for the removal Cd2+ metal from wastewater. The as-prepared CH–CDs membranes show relatively good mechanical properties, based on stress resistance and flexibility to facilitate handling. The equilibrium state was reached within 5 min. Intriguingly, the UV-light illuminations enhanced the Cd2+ removal efficiency of the photoluminescent CDs substantially by four times faster under. It was found that adsorption followed pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity at 25 °C was found to be 112.4 mg g−1 at pH 8. This work paves the way to new applications of CDs in water treatment.[Figure not available: see fulltext.]

Anti-corrosive and oil sensitive coatings based on epoxy/polyaniline/magnetite-clay composites through diazonium interfacial chemistry

Epoxy polymer nanocomposites filled with magnetite (Fe3O4) clay (B), named (B-DPA-PANI@Fe3O4) have been prepared at different filler loading (0.1, 0.5, 1, 3, 5 wt. %). The surface modification of clay by polyaniline (PANI) is achieved in the presence of 4-diphenylamine diazonium salt (DPA). The effects of the nanofiller loading on Tensile, mechanical and dielectric properties were systematically studied. Improved properties was highlighted for all reinforced samples. The addition of only 3 wt. % of the filler enhanced the tensile strength of the composites by 256%, and the glass transition temperature Tg by 37%. The dielectric spectra over a broad frequency showed a robust interface between the hybrid (B-DPA-PANI@Fe3O4) fillers and epoxy matrix. The results showed most significant improvement in corrosion inhibition using electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl, as well as a significant response in oil sensing test. High charge transfer resistance of 110 × 106 Ω.cm2 using 3-wt % of filler was noted compared to 0.35 × 106 Ω.cm2 for the pure epoxy. The results obtained herein will open new routes for the preparation of efficient anticorrosion sensor coatings. © 2018, The Author(s).NPRP Award from the Qatar National Research Fund (a member of Qatar Foundation) [8-878-1-172

Can Plasmon Change Reaction Path? : Decomposition of Unsymmetrical Iodonium Salts as an Organic Probe

Plasmon-assisted transformations of organic compounds represent a novel opportunity for conversion of light to chemical energy at room temperature. However, the mechanistic insights of interaction between plasmon energy and organic molecules is still under debate. Herein, we proposed a comprehensive study of the plasmon-assisted reaction mechanism using unsymmetric iodonium salts (ISs) as an organic probe. The experimental and theoretical analysis allow us to exclude the possible thermal effect or hot electron transfer. We found that plasmon interaction with unsymmetrical ISs led to the intramolecular excitation of electron followed by the regioselective cleavage of C–I bond with the formation of electron-rich radical species, which cannot be explained by the hot electron excitation or thermal effects. The high regioselectivity is explained by the direct excitation of electron to LUMO with the formation of a dissociative excited state according to quantum-chemical modeling, which provides novel opportunities for the fine control of reactivity using plasmon energy.Peer reviewe

Beyond graphene oxide: Laser engineering functionalized graphene for flexible electronics

Carbon nanomaterials, especially graphene, are promising due to their abundance and the possibility to exploit them in lightweight, flexible, and wearable electronics enabling paradigms such as the Internet of Things. However, conventional methods to synthesize and integrate graphene into functional materials and flexible devices are either hazardous, time demanding, or excessively energy-consuming. To overcome these issues, here we propose a new concept based on the laser processing of single-layer diazonium-functionalized graphene. This is a safe, inexpensive, and environmentally-friendly method making it a competitive alternative for graphene-device fabrication. Flexible chemiresistors exhibit sensitivity for breath (water vapor and CO2) and ethanol detection up to 1500% higher than laser-reduced graphene oxide devices. We attribute this enhanced sensitivity to an optimal balance between structural defects and electrical conductivity. Flexible electronic circuits demonstrate a superb resilience against scratching and high current stability up to 98% with durability against 180° bending cycles for continuous operation of several weeks. This work can impact biomedical technology and electronics where tunable electrical conductivity, sensitivity, and mechanical stability are of uttermost importance. © 2020 The Royal Society of Chemistry

Preparation and optical properties of novel bioactive photonic crystals obtained from core-shell poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microspheres

Optical properties of polymer microspheres with polystyrene cores and polyglycidol-enriched shells poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) (P(S/PGL) particles with number average diameters Dn determined by scanning electron microscopy equal 237 and 271 nm), were studied before and after immobilization of ovalbumin. The particles were synthesized by emulsifier-free emulsion copolymerization of styrene and polyglycidol macromonomer (poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol)) initiated with potassium persulfate. Molar fraction of polyglycidol units in the interfacial layer of the microspheres determined by XPS was equal 42.6 and 34.0%, for the particles with Dn equal 137 and 271 nm, respectively. Colloidal crystals from the aforementioned particles were prepared by deposition of particle suspensions on the glass slides and subsequent evaporation of water. It was found that optical properties of colloidal crystals from the P(S/PGL) microspheres strongly depend on modification of their interfacial layer by covalent immobilization of ovalbumin. The coating of particles with ovalbumin resulted in decreasing their refractive index from 1.58 to 1.52

Chapter 1 - Overview: Clay Preparation, Properties, Modification

This chapter reviews clay physicochemical properties and general methods of modification with a view to making a clay–polymer nanocomposite. The first part includes an overview of clays, their different structures, and their physicochemical properties. The second part concerns a literature survey of the most applied methods of organic modification of clays. New trends are also highlighted.This chapter was made possible by NPRP award [8-878-1-172] from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors

Versatile biogenesis of Silver-Copper nanoparticles over arylated pulp sugarcane bagasse- derived biochar: high catalytic performance

Agrowaste-derived materials for the supporting of nanocatalysts is attracting a great attention due to the abundance and the physicochemical features they provide as bio-sourced underlying materials. The main idea is built around the conversion of junk material into functional material, a journey of waste from "trash to treasure". Herein, we suggest a versatile method to elaborate phytochemically reduced Ag/Cu nanoparticles supported on aryl-sulfonated sugarcane bagasse pulp-derived biochar. Biochar was first prepared by a slow pyrolysis of the biomass at 500°C under N2:H2 95%:5% inert atmosphere. Thereafter, in-situ arylation of the biochar surface has been performed to obtain SO3H-biochar. Silver and copper ions loading in SO3H-biochar has been established via a wet impregnation in a hydroalcoholic medium. Finally, the natural liquid extract of sugarcane bagasse has been employed to reduce the metallic ions instead of the toxic NaBH4 very commonly used, the obtained SO3H-biochar@Ag/Cu has been characterized by XRD, XPS, SEM and RAMAN spectroscopy. The catalytic activity of the nanocomposite has been investigated in the oxidative degradation of malachite green oxalate. A total mineralization of the dye has been registered and the experimental data was found to give a relatively good fitting to the pseudo-first-order model with a mineralization apparent constant rate equals to 65 10-3 min-1