Clay Mineral Polymer Nanocomposites Research Articles

Synthesis and characterization of conducting aniline and o-anisidine nanocomposites based on montmorillonite modified clay

A study on clay mineral polymer nanocomposites (CPN), namely polyaniline/montmorillonite-cetyltrimethylammonium bromide (PANI/Mt-CTAB), poly o-anisidine/montmorillonite-cetyltrimethylammonium bromide (poly(o-ANIS)/Mt-CTAB) and poly o-anisidine-co-aniline/montmorillonite-cetyltrimethylammonium bromide (poly(o-ANIS-co-ANI)/Mt-CTAB), synthesized by oxidative chemical polymerization method is presented. The nanocomposites have been characterized by Fourier transform infrared spectroscopy, UV–vis spectroscopy, and cyclic voltammetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and thermogravimetry and differential scanning calorimetry analysis. By UV–vis measurements different electronic transitions for the CPNs were pointed out. The voltammograms indicate that the synthetized materials are electroactive. The FTIR analysis reveals the characteristic bands of the polymers and of the Mt-CTAB. The shift of the bands to higher/lower wavenumbers demonstrate the interaction between the pristine polymers macromolecular chains and the montmorillonite (Mt). The intercalation of the polymers inside the mineral clay was confirmed by the increased interlayer distance connected with the position of the 011 diffraction plane of the Mt., and the intercalation and exfoliation states were highlighted in the scanning and transmission electron microscopy images.The obtained results are encouraging in respect with the purpose to use them in the field of photovoltaic applications.

Hybrid organo-montmorillonite produced by simultaneous intercalation of phosphonium and ammonium/amine based surfactants

This study describes the preparation and characterization of hybrid organo-modified montmorillonite (OMt) produced by intercalation of phosphonium-based plus ammonium and/or amine-based surfactants, aiming to improve thermal and compatibility properties for the manufacture of clay mineral polymer nanocomposites (CPN). The choice of the surfactants was based on previous studies, which have pointed out that the phosphonium-based surfactant provided the clay mineral a high thermal stability but low d001-value and hydrophobicity. On the other hand, ammonium-based compounds presented inverse properties, i.e., low thermal stability and high d001-value. The present work was supported by design of experiments (DOE) considering different surfactant concentrations. The materials were analyzed by thermogravimetric analysis (TGA) to evaluate the thermal stability and relative reactional yield, by X-ray diffraction (XRD), to evaluate the surfactant intercalation by d001 of the clay, also by Fourier-transform infrared spectroscopy (FTIR) and contact angle, to verify the components interaction and the hydrophobicity. The hybrid montmorillonites presented intermediate properties, as thermal stability and basal space, when compared with the clay modified by the single modifiers. The intercalated species were arranged in paraffin-type structure and their conformation and tilt angle changed by increasing the ammonium concentration. Statistical analysis allowed knowing the concentration effects of each surfactant on hybrid materials. From the statistical models, an optimized formulation considering the maximum d001-value, Tonset (initial temperature of thermal degradation) and yield responses was prepared, which had its significance tested by Anova and F-test, and was validated by experimental values.

Mechanical and Thermal Properties of Poly(Tetrahydrofurfuryl Methacrylate) Nano-Composites

ABSTRACTTo obviate the brittleness and improve the mechanical properties of poly(tetrahydrofurfuryl methacrylate) (PTHFMA), clay mineral nano-composites of PTHFMA with two different montmorillonites (MMT), Cloisite® 20A and Cloisite® 30B, were prepared. The mechanical properties were investigated by dynamic mechanical analysis (DMA) and nanoindentation. The thermal properties of the nano-composites were studied using thermogravimetric analysis (TGA). According to the DMA results, tanδ was increased by addition of the clay, leading to the improvement in the mechanical properties which was also confirmed by the nanoindentation results. TGA thermograms showed better thermal stability for the nano-composites compared to that of the homopolymer. Considering all results, the clay mineral polymer nano-composites (CPN) with Cloisite® 20A exhibited better properties compared to those with Cloisite® 30B. Transmission electron microscopy (TEM) micrographs, and X-ray diffraction (XRD) patterns validated intercalation-exfoliation of the clay mineral layers for the Cloisite 20A and intercalation of the Cloisite 30B in the polymer matrix.

Feasible preparation and characterization of tunable novel montmorillonite/block-copolymers based composites as potential dual adsorbent candidates

This study was mainly focused on exploring the possible intercalation of block-(diblock or triblock) copolymers into montmorillonite (Mt) to obtain clay mineral polymer nanocomposites (CPN) aiming to increase the interlayer space and application of Mt. The extent of the effect on interlayer space of Mt during reaction was studied in details. N2 adsorption isotherms and X-ray diffraction (XRD) studies were used to confirm the formation of CPN. It was found that the intercalation of polymers enhanced the interlayer space of Mt along with a shift of [001] plane 2θ (6.8°) to lower values. The corresponding interlayer space was increased from 12.65Å to 40.85Å. The intercalation of polymers to form CPN favors both structural orientations and functional groups for the preferential adsorption of both ionic (cationic and anionic inorganic) and non-ionic (organic, NOC) pollutants. Uptake of both organic (toluene; ethylbenzene; and xylene; in brief TEX) and inorganic (Cu2+, Pb2+ and Cr2O72−) pollutants were explored and highlighted in this study. The observed log KOC values for the distribution of organic pollutants onto CPN are significantly high in this study. In all cases the adsorption of Pb2+ was comparatively larger than that of Cu2+. Among all the obtained CPN, M-D-DMF displayed enhanced adsorption of both organic and inorganic pollutants and hence it was concluded as a potential candidate.

Quantification and key factors in delamination of (Mg1 − yNiy)1 − xAlx(OH)2(NO3)x·mH2O

Dispersions of delaminated layered double hydroxides (LDH) contain nanosheets of interest for single particle studies and for preparation of different types of clay mineral-clay mineral or clay mineral–polymer nanocomposites and coatings. Reproducible methods were currently benchmarked, key parameters influencing the degree of delamination were identified, and prerequisites for achieving high yield delamination routes evaluated. Inert synthesis, screening by turbidity measurements and gravimetric quantification allowed identification of how various parameters influence delamination. For (Mg1−yNiy)1−xAlx(OH)2(NO3)x·mH2O preparative parameters as hydrothermal treatment, drying conditions and pH during synthesis have significant impact on delamination abilities. Poorly delaminating Ni0.75Al0.25(OH)2(NO3)0.25·mH2O LDH is by adequate hydrothermal treatment converted to a material that undergoes almost complete delamination. The adopted procedures allow systematic studies on how preparative parameters as well as more chemical parameters such as interlayer chemistry and cationic composition in the brucite like layers interacts with solvent properties. Improved insight into parameters controlling delamination properties open up for routes on large scale manufacturing of clay mineral-clay mineral nanocomposites requested for novel types of catalysts. Particles, dispersions and nanosheets were characterized by ICP-OES, CN-analysis, turbidity, XRD, TEM, SAXS, AFM and XPS measurements.

Effect of the montmorillonite intercalant and anhydride maleic grafting on polylactic acid structure and properties

The goal of this work is to prepare maleic anhydride grafted poly(lactic acid) (PLAgMA) according to a method described by Hwang et al. in order to investigate its effect as matrix and as compatibilizer on the dispersion of two organic nanofillers into PLA matrix, as well as its effect as compatibilizer on rheological and barrier properties of clay mineral–PLA nanocomposites. Two different montmorillonites, Cloisite® 20A and Cloisite® 30B, are used in this study. The latter is classically used in pristine PLA nanocomposites. The clay mineral polymer nanocomposites are prepared by the incorporation of 3 mass % of each layered silicate into PLA, PLAgMA and PLA/PLAgMA via melt blending. Transmission electron microscopy micrographs of the PLAgMA/Cloisite® blends showed the presence of intercalated and partially exfoliated areas with Cloisite® 20A and re-aggregation of the layered silicates with Cloisite® 30B. These results are confirmed by rheological behaviors, which showed their dependence on the content of maleic anhydride and nature of montmorillonite. Water vapor permeations (WVP) were strongly reduced by the incorporation of Cloisite®, and the better results are obtained with C20A/PLA containing 5 mass % of PLAgMA.

Antibacterial activities of copper nanoparticle-decorated organically modified montmorillonite/epoxy nanocomposites

Organically modified montmorillonite (OMt) was decorated by copper nanoparticles (with average diameters of 10 to 20nm) at three different mass percentages at room temperature. Such OMt-Cu nanohybrid was incorporated into Mesua ferrea L. seed oil modified epoxy resin (BPSE) to obtain clay mineral polymer nanocomposites (CPN). The nanohybrids and CPN were characterized by SEM, XRD, HRTEM and FTIR and UV–visible spectroscopic techniques. The antimicrobial efficacy of the as-prepared OMt-Cu nanohybrid and OMt-Cu/epoxy nanocomposites was also premeditated and significant antibacterial activity against ubiquitous Gram negative bacteria Klebsiella pneumonia and Gram positive bacteria Staphylococcus aureus was observed. In addition the OMt-Cu/epoxy nanocomposites exhibited enhancement in thermostability over the pristine system by 15°C and tensile strength and in scratch hardness by 2.5 and 2.1units respectively along with marginal improvement in the elongation at break value. The study reveals that the OMt-Cu/epoxy nanocomposites have the potentiality to be used as advanced antimicrobial materials.

Preparation of clay mineral polymer nanocomposites by adsorption in solution

Novel clay mineral polymer nanocomposites (CPN) were prepared by direct addition of a polyesteramide (PEA) solution to organomontmorillonites (OMt). PEA matrices were obtained by the anionic copolymerization of ε-caprolactam (CLA) and ε-caprolactone (CLO) containing 20–100mol% of CLO units. The matrices were used to test the exfoliation of two OMt (Cloisite 30B and Cloisite 25A). The extent of exfoliation was dependent on the mutual interaction of all three components (polymer, solvent and OMt). The degree of OMt–solvent interaction was assessed from the swelling factor and basal distance, the latter being measured by the WAXS method. The polymer–solvent interaction was determined from the limiting viscosity numbers measured for each solvent used. Several of the copolymer–solvent–OMt combinations resulted in nanocomposites with a fully- or partially-exfoliated structure.

Hydrothermal synthesis of magadiite

Intercalation of organic guest species into layered silicates is a way to construct clay mineral–polymer nanocomposites. An example is magadiite Na 2Si 14O 29·9H 2O which like smectites intercalates organic species. Using hydrous silica precipitated from water glass with dilute HCl in aqueous dispersions of NaOH and Na 2CO 3, well-crystallized magadiite as a single phase was synthesized at 150 °C for 24 h or 170 °C for 9 h.

Organo clay mineral–melted polyolefin nanocomposites Effect of surfactant/CEC ratio

Abstract Clay mineral–polymer nanocomposites are prepared by dispersing solid organo clay minerals in two different melted polyolefin matrices, namely polyethylene (PE) and ethylene vinyl acetate (EVA). The organo clay minerals are prepared by adding different amounts of surfactant corresponding to the CEC of the pristine clay mineral. The characteristics of the organo clay minerals are obtained by XRD, IR spectroscopy, TGA, and swelling volume measurements. The amount of added surfactant has a direct effect on the interlayer separation and organophilicity–hydrophilicity balance of the clay mineral, evidencing a particular behavior transition about OMt1.2 The intercalation of PE is found to be dependent on the interlayer distance of the organo clay minerals while EVA intercalates in the organo clay minerals whatever the amount of surfactant (> 0.5CEC), leading to the same interlayer spacing (4 nm). The polymer intercalation is more homogeneous in clay minerals having high surfactant loading corresponding to 1.5 and 2 CEC. Cone calorimeter results of the studied nanocomposites show a PHRR reduction of 32% for PE–OMt1.5 and of 47% for EVA–OMt1. For both polymers, the best compromise between mechanical and thermal properties, is obtained for organoclay filler obtained with an amount of added surfactant in a range 1–1.5 CEC.