Saad Lamouri

Synthesis of poly(furfuryl alcohol)/montmorillonite nanocomposites by direct in-situ polymerization

The purpose of this study was to obtain poly(furfuryl alcohol) nanocomposites with Algerian organically modified clay (termed 12-montmorillonite). The formation of poly(furfuryl alcohol) was confirmed by infrared spectroscopy (IR); the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The evolution of mechanical properties was also studied. The obtained results confirm the intercalation of molecules of salt in the clay layers, and a good interaction with the polymer, showing the formation of intercalated and/or exfoliated structures. The nanocomposites showed higher thermal stability compared to pure polymer, and the mechanical properties presented interesting and promising results.

A Comprehensive Study and Characterization of Colloidal Emeraldine-Base

Soluble emeraldine-base (PANI-EB) was prepared and its structure was characterized using 1H, 13C and 2D (COSY, HMQC and HMBC) NMR. The solubility of the polymer in two solvents (N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO), the structure of the solution (aggregation) and the behavior of polyaniline were studied by viscometry and by dynamic light scattering (DLS) in dilute solution. Viscometric behavior in NMP and Huggins constant determination confirm supramolecular interactions also evidenced by DLS; at end, the molecular weight of the soluble fraction of PANI-EB is determined.

Study of Electrical Conductivity of Para-Toluene Sulfonic Acid Doped Polyaniline/Polyester-Based Polyurethane Blends in the S-Band Frequency Range

Conducting polymer blends were prepared using polyaniline doped with para- toluene sulfonic acid (PTSA-PANI) and a polyester polyol-based polyurethane (PU). The morphological, thermal and dielectric properties of the PTSA-PANI/PU blends in the frequency range of 1–5 GHz (S band) were investigated. It was found that the morphology of the samples was affected by the PTSA-PANI loading, resulting in the formation of agglomerates and pathways when above 10 wt%. The thermal stability of the composites was improved with increased PTSA-PANI loading. The electrical conductivity percolation threshold was obtained at 2.5% of PTSA-PANI loading and the electrical conductivity reached the value of 0.13 S/m at a PTSA-PANI loading of 30 wt%. The obtained results for the PTSA-PANI/PU blends prepared indicate a high potential for their successful use in electrical and electromagnetic applications.

Preparation and characterization of a new polyaniline salt with good conductivity and great solubility in dimethyl sulfoxyde

In this study, we propose a novel conducting and soluble polyaniline salt prepared by chemical polymerization in the presence of new doping agent (IAs). This last is prepared by sulphonation of itaconic acid (IA) with concentrated sulphuric acid in THF. The obtained doped polyaniline (PANI-IAs) is extremely soluble in dimethyl sulfoxyde (DMSO) at room temperature, in which the solubility reach 44 mg mL -1 . The conductivity measurement of doped polyaniline powder precipitated in THF as dispersing medium gave a value of 0.13 S cm -1 when the emeraldine base form of polyaniline is fully protonated. The polyaniline salt sample is characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction, UV-Visible spectra and FTIR spectra.

Maghnite-H+ as Inorganic Acidic Catalyst in Ring Opening Polymerization of Dodecamethylcyclohexasiloxane

A new procedure for synthesizing a dimethyl siloxane polymer is addressed in the present work, which is based on the use of Maghnite-H+ as a green and environmentally friendly catalyst in the polymerization of dodecamethylcyclohexasiloxane (D6). The Maghnite-H+ is natural smectite clay, activated by a strong acid, sulfuric acid is generally the most used. The impact of acid activation appears in increasing the basal spacing of the Maghnite, it is confirmed by XRD analysis. The solvent-free polymerization of D6 by cationic route using the Maghnite-H+ has been made, the product obtained was characterized by different methods of analysis as IR, 1H NMR, 13C NMR and GPC. Temperature, time and mass content of catalyst were optimized so to obtain a yield and an average molecular mass large enough and without cyclic structures. Also, the thermal behavior of the polymer was investigated by DSC. At the end, a reaction mechanism was proposed which describes in detail the role played by the Maghnite-H+ during the various stages of the reaction.

A new approach for the polymerization of tetraphenyltetramethylcyclotetrasiloxane by an environmentally friendly catalyst called Maghnite-H+

Abstract This work is devoted to the study of the cationic ring opening polymerization of tetraphenyltetramethylcyclotetrasiloxane (D4Ph,Me), using a solid green catalyst prepared by the activation of a natural clay by sulfuric acid (Maghnite-H+). This treatment leads to the spacing of the montmorillonite sheets due to the substitution of the existing interlayer cations by the protons of the acid. This consequence is clearly shown on the X-ray diffraction (XRD) spectrum. The polymerization reaction proceeded in bulk and under mild conditions. Various tests were carried out by changing the temperature, the time and the catalyst mass content in order to increase, at the same time, the yield of the reaction and the average molecular mass of the polyphenylmethylsiloxane (PPMS) obtained. The structure of the PPMS obtained was identified by infrared (IR), 1H nuclear magnetic resonance (NMR) and 13C NMR analyses over different periods of time. The thermal behavior was investigated by differential scanning calorimetry (DSC) analysis. At the end, in order to show the role played by the Maghnite-H+ during the various reaction stages, a reaction mechanism was proposed.

Activated bentonite (Maghnite-H + ) as green catalyst for ring-opening polymerization of 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane

AbstractA new green technique to synthesize polysiloxane-type polymers is suggested based on use of chemically modified clay (Maghnite-H+) as heterogeneous, cost-effective, environmentally friendly catalyst for polymerization of 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane (V4D4) under gentle conditions and without solvent. Maghnite-H+ is an ion-exchanged montmorillonite prepared by treatment with sulfuric acid, which leads to increased interplanar spacing due to intercalation of acid protons between sheets, a crystalline change clearly seen in the X-ray diffraction (XRD) spectrum. Polymers obtained under different conditions were characterized by infrared (IR) and 1H and 13C nuclear magnetic resonance (NMR) analyses and their thermal behavior studied by differential scanning calorimetry (DSC) analysis. The average molecular mass and dispersity were followed by gel permeation chromatography (GPC) by varying the operating conditions. A reaction mechanism is proposed to understand the role played by Maghnite-H+ during the various stages of the reaction.

Synthesis and characterization of polyvinylmethylsiloxanes by cationic polymerization using a solid green catalyst

Abstract The present work is devoted to the synthesis and characterization of vinylsiloxane polymers produced by the use of an activated natural catalyst known as Maghnite-H+. The cationic ring opening polymerization of pentavinylpentamethylcyclopentasiloxane (V5D5) made it possible to obtain the desired polymeric materials. Through this study, we have adapted a new strategy of synthesis of a siloxane polymer with relatively high molecular mass, using a solid initiator activated by sulfuric acid, which has enabled us to combine the ecological aspect of synthesis and the effectiveness of the catalyst in this kind of reaction. Structural [infrared (IR), proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR)], thermal differential scanning (DSC) and chromatographic (GPC) characterization methods have allowed the products obtained to be identified and their various properties to be focused on. The kinetic study was made to determine the order of the reaction. The proposed reaction mechanism shows the advantages of Maghnite-H+.