Characterization of polypropylene/layered silicate nanocomposites prepared by single-step method

The extent of organo-modified clay (C93A) platelets dispersion in polymer matrix and crystallization and melting behavior of iPP-based nanocomposites prepared by a single-step melt-mixing method were investigated by wide-angle X-ray diffraction (WAXD), transmission (TEM), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). WAXD patterns revealed exfoliated structure of nanocomposites containing 1 wt% clay, and mixed intercalated/exfoliated structure at higher concentration of nanoclay. The isothermal crystallization proceeds faster in the matrix polymer (iPP/PP-g-MA) than in nanocomposite samples. The results obtained for T _m ^o suggest that the presence of nanoclay has induced a perfection of the formed crystals. The presence of C93A particles in PP leads to increase in crystallization peak temperature implying nucleating ability of clay particles, which was more pronounced in exfoliated than in mixed intercalated/exfoliated system.     

Synthesis of polybenzoxazine/clay nanocomposites by in situ thermal ring‐opening polymerization using intercalated monomer

A new class of polybenzoxazine/montmorillonite (PBz/MMT) nanocomposites has been prepared by the in situ polymerization of the typical fluid benzoxazine monomer, 3‐pentyl‐5‐ol‐3,4‐dihydro‐1,3‐benzoxazine, with intercalated benzoxazine MMT clay. A pyridine‐substituted benzoxazine was first synthesized and quaternized by 11‐bromo‐1‐undecanol and then used for ion exchange reaction with sodium ions in MMT to obtain intercalated benzoxazine clay. Finally, this organomodified clay was dispersed in the fluid benzoxazine monomers at different loading degrees to conduct the in situ thermal ring‐opening polymerization. Polymerization through the interlayer galleries of the clay led to the PBz/MMT nanocomposite formation. The morphologies of the nanocomposites were investigated by both X‐ray diffraction and transmission electron microscopic techniques, which suggested the partially exfoliated/intercalated structures in the PBz matrix. Results of thermogravimetric analysis confirmed that the thermal stability and char yield of PBz nanocomposites increased with the increase of clay content. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Microscopic structures of adsorbed cationic porphyrins on clay surfaces: molecular alignment in artificial light-harvesting systems

The intercalation behavior of cationic porphyrin derivatives within the interlayer spaces of nano-layered clay minerals has been investigated. The porphyrins were successfully intercalated by the newly adopted method of repeated freeze-thaw cycles. The absorption spectra of the porphyrins were compared in the solution phase, adsorbed onto the exfoliated clay nano-sheets, intercalated within the interlayer spaces of clay sheets dispersed in water and intercalated in dry films. Substantial red shifts of the λ_max values in the absorption spectra of the porphyrins were observed on the exfoliated clay sheets, and further red shifts were induced within the interlayer space. The dry films of the intercalated samples exhibited the largest red shifts. X-ray diffraction studies revealed that the clearance space between the layers in these intercalated hybrid compounds is only large enough for the porphyrins to be rigidly packed parallel to the clay layer. For the exfoliated clay nano-sheets, theoretical calculations were carried out on the correlation between the dihedral angle of the meso-substituted pyridiniumyl plane vs. the porphyrin ring and the λ_max of the porphyrin Soret band. An extrapolation of the experimental λ_max value to the correlation curve, afforded the dihedral angle to be 61.6°. The microscopic structure of the adsorbed state of the cationic porphyrins on the exfoliated clay nano-sheets was, thus, proposed to involve an orientation parallel to the clay surface, with a distance of 0.15 nm from the surface, which implies the expulsion of the solvent water molecules.     

Nonisothermal cold crystallization behavior and kinetics of polylactide/clay nanocomposites

The nonisothermal cold crystallization behavior of intercalated polylactide (PLA)/clay nanocomposites (PLACNs) was studied using differential scanning calorimetry, polarized optical microscope, X‐ray diffractometer, dynamic mechanical thermal analysis, and Fourier transform infrared spectrometer. The results show that both the cold crystallization temperature (T_cc) and melting point (T_m) of PLA matrix decreases monotonously with increasing of clay loadings, accompanied by the decreasing degree of crystallinity (X_c%) at the low heating rates (≤5 °C/min). However, the X_c% of PLACNs presents a remarkable increase at the high heating rate of 10 °C/min in contrast to that of neat PLA. The crystallization kinetics was then analyzed by the Avrami, Jezioney, Ozawa, Mo, Kissinger and Lauritzen–Hoffman kinetic models. It can be concluded that at the low heating rate, the cold crystallization of both the neat PLA and nanocomposites proceeds by regime III kinetics. The nucleation effect of clay promote the crystallization to some extent, while the impeding effect of clay results in the decrease of crystallization rate with increasing of clay loadings. At the high heating rate of 10 °C/min, crystallization proceeds mainly by regime II kinetics. Thus, the formation of much more incomplete crystals in the PLACNs with high clay loadings due to the dominant multiple nucleations mechanism in regime II, may have primary contribution to the lower crystallization kinetics, also as a result to the higher degree of crystallinity and lower melting point in contrast to that of neat PLA. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1100–1113, 2007     

Long‐lived layered silicates‐immobilized 2,6‐bis(imino)pyridyl iron (II) catalysts for hybrid polyethylene nanocomposites by in situ polymerization: Effect of aryl ligand and silicate modification

Heterogeneous‐layered silicate‐immobilized 2,6‐bis(imino)pyridyl iron (II) dichloride/MMAO catalysts, in which the active polymerization species are intercalated within sodium‐ and organomodified‐layered silicate galleries, were prepared for producing hybrid exfoliated polyethylene (PE) nanocomposites by means of in situ polymerization. The inorganic filler was first treated with modified‐methylaluminoxane (MMAO) to produce a supported cocatalyst: MMAO reacts with silicates replacing most of the organic surfactant, thus modifying the original crystallographic clay order. MMAO anchored to the nanoclay was able to activate polymerization iron complexes initiating the polymer growth directly from the filler lamellae interlayer. The polymerization mechanism taking place in between the montmorillonite lamellae separates the layers, thus promoting deagglomeration and effective clay dispersion. Transmission electron microscopy revealed that in situ polymerization by catalytically active iron complexes intercalated within the lower organomodified clay led to fine dispersion and high exfoliation extent. The intercalated clay catalysts displayed a longer polymerization life‐time and brought about ethylene polymerization more efficiently than analogous homogeneous systems. PEs having higher molecular masses were obtained. These benefits resulted to be dependent more on the filler nature than on the ligand environment around the iron metal center and the experimental synthetic route. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 548–564, 2009     

Flow injection determination of anionic polyelectrolytes using an anionic surfactant-selective plasticized poly(vinyl chloride) membrane electrode detector

 A potentiometric flow injection method for the determination of anionic polyelectrolytes utilizing a flow-through type surfactant-selective electrode detector is described. The method is based on the detection of the concentration increase of anionic surfactant liberated from a reagent stream containing an ion associate between cationic polyelectrolyte, poly(diallyldimethylammonium chloride) and anionic surfactant, dodecylbenzenesulfonate, which is caused by the formation of a polyion complex between cationic and anionic polyelectrolytes. The response of the electrode detector as a peak-shaped signal was obtained for injected anionic polyelectrolyte samples. A linear relationship was found to exist between peak height and the logarithmic concentration of potassium poly (vinyl sulfate) (PVSK) with a slope of 30 mV decade^-1 in a concentration range of 1.0×10^-4 to 1.0×10^-3 mol/L. Identical relationships were obtained for sodium alginate and carageenan (also anionic polyelectrolytes) as for PVSK but with a lower sensitivity. The detection limit for PVSK was 2.5×10^-5 mol/L. The relative standard deviation for 5 injections of a 2.5×10^-4 mol/L PVSK solution was 1.3% and the sampling rate was ca. 10 samples h^-1. Received: 9 April 1996/Revised: 8 July 1996/Accepted: 14 July 1996     

Impact of the clay organic modifier on the morphology of polymer–clay nanocomposites prepared by in situ free‐radical polymerization in emulsion

Poly(styrene‐co‐butyl acrylate) copolymers were prepared by free‐radical random copolymerization of styrene and butyl acrylate in emulsion in the presence of 10% of surface‐modified sodium montmorillonite (Na‐MMT). The objective of this work was to evaluate the impact of the clay organic modifier in terms of its chemical structure, its degree of interaction within the clay galleries surface, and its ability to copolymerize with monomers, on the morphology and properties of the final nanocomposite prepared. Na‐MMT was modified using different organic modifiers, namely: sodium 1‐allyloxy‐2‐hydroxypropyl (Cops), 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS), N‐isopropylacrylamide (NIPA), and sodium 11‐methacryloyloxy‐undecan‐1‐yl sulfate (MET), respectively. The morphology and properties of the nanocomposites obtained were found to be dependant on the clay organic modifier. X‐ray diffraction (XRD) and transmission electron microscopy indicated that, nanocomposites at 10% clay loading with Cops‐, NIPA‐, and MET‐modified clays, yielded intercalated to partially exfoliated structures, whereas AMPS‐modified clay gave a nanocomposite with a fully exfoliated structure. All polymer–clay nanocomposites were found to be more thermally stable than neat poly(S‐co‐BA) as were determined by TGA. However, nanocomposites with intercalated structures exhibited greater thermal stability relative to fully exfoliated ones. Furthermore, nanocomposites with exfoliated structures exhibited higher storage moduli (G^I) than partially exfoliated once, whereas intercalated structure showed the lowest G^I values. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3619–3628, 2008     

Molecular Dynamics Study of N-Dodecyl-N,N-Dimethyl-3-Ammonio-1-Propanesulfonate Mono-Layer Adsorbed at the Air/Water Interface

Molecular dynamics (MD) simulation has been carried out to investigate the properties of a mono-layer of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB12-3) adsorbed at the air/water interface. The simulation results show that SB12-3 can form a closely packed mono-layer at the air/water interface, the anionic sulfonic groups of the hydrophilic head group have stronger interactions with the water molecules by comparison with the cationic quaternary nitrogen of the hydrophilic head group, and water molecules can gather more easily and aggregate around the sulfonic groups. With the addition of the Ca²⁺ ions, the number of hydrogen bonds between the SB12-3 surfactant molecules and water molecules remains almost unchanged, which may explain the salt resistance behavior for SB12-3 especially for di-valent ions. The hydrophobic tail in SB12-3 is more ordered in the beginning of the chain.     

Stereoregular P(MMA)‐clay nanocomposites by metallocene catalysts: In situ synthesis and stereocomplex formation

This contribution reports the synthesis and characterization of stereochemically controlled, as well as crystalline stereocomplex, P(MMA)‐clay nanocomposites using metallocene complexes and alane‐intercalated clay activators. The ligand elimination and exchange reactions involving Lewis acids E(C₆F₅)₃ (E = Al, B) and an organically modified montmorillonite clay were employed to synthesize the alane‐intercalated clay activators. When combined with dimethyl metallocenes of various symmetries, these clay activators brought about efficient MMA polymerizations leading to in situ polymerized, stereochemically controlled P(MMA)‐intercalated clay nanocomposites. The most noticeable thermal property enhancement observed for the clay nanocomposite P(MMA), when compared with the pristine P(MMA) having similar molecular weight and stereomicrostructure, has a considerable increase in T_g (≥10 °C). Mixing of dilute THF solutions of two diastereomeric nanocomposites in a 1:2 isotactic to syndiotactic ratio, followed by reprecipitation or crystallization procedures, yielded unique double‐stranded helical stereocomplex P(MMA)‐clay nanocomposites with a predominantly exfoliated clay morphology. Remarkably, the resulting crystalline stereocomplex P(MMA) matrix is resistant to the boiling‐THF extraction and its clay nanocomposites exhibit high T_m of 201 to 210 °C. Furthermore, the stereocomplex P(MMA)‐clay nanocomposite shows a one‐step, narrow decomposition temperature window and a single, high maximum rate decomposition temperature of 377 °C. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2581–2592, 2007     

药物-无机复合材料姜黄素嵌入镁铝水滑石的合成、表征及缓释性能的研究

采用共沉淀和离子交换方法将药物姜黄素(Cur)嵌入到Mg-Al-LDHs层间,制备了一种新型的药物-无机复合材料,借助XRD,FTIR和TG-DTA等手段对样品进行了表征。结果表明,Cur阴离子以平行或者单层、沿其短轴方向垂直嵌入到层间;与主体层板通过氢键与静电作用形成超分子结构;该超分子结构姜黄素-水滑石复合材料与姜黄素相比,其热稳定性、耐酸性及缓释性能均有大幅度提高,缓释实验数据符合Bhaskar方程和一级动力学方程模型。     

Thermogravimetric study of <Emphasis Type="Italic">n</Emphasis>-alkylammonium-intercalated montmorillonites of different cation exchange capacity

Three n-alkylammonium salts of varying alkyl chain length were ion exchanged with montmorillonites (MMT) of different cation exchange capacity (CEC). The intercalated MMTs were characterized by thermogravimetry (TG), XRD, FTIR to acquire an insight into the intergallery structural arrangement of the organic alkylammonium cations (AAC). The increment in the intergallery spacing from XRD pattern was correlated with chain length and interlayer arrangement of AAC. Multiple organic mass-loss stages in thermogravimetric analysis indicate two types of anchorage of AAC in intercalated clay. CEC of MMT was found to influence the intergallery confinement and excess adsorption of AAC.     

Thermogravimetric analysis of different molar mass ammonium cations intercalated different cationic forms of montmorillonite

Different cationic forms of montmorillonite, mainly K-, Na-, Ca- and Mg-montmorillonites were intercalated in this study via ion exchange process with mono-, di-, and triethanolammonium cations. The developed samples were characterized by TG, XRD, and CHNS techniques. Thermogravimetric study of ammonium-montmorillonites shows three thermal transition steps, which are attributable to the volatilization of the physically adsorbed water and dehydration, followed by the decomposition of the intercalated ammonium cations and dehydroxylation of the structural water of the modified clay, respectively, while untreated and cationic forms of montmorillonite showed only two decomposition steps. The type of ammonium cation has affected both desorption temperature (Position) and the amount of the adsorbed water (intensity). XRD results show a stepwise change in the crystallographic spacings of montmorillonite with the molar mass of ammonium cation, reflecting a change in the structure of the clay. CHNS data confirm the intercalation of ammonium cations into the interlayer space of montmorillonite and corroborate the effect of the molar mass of ammonium cation on the amount adsorbed by the clay.     

Studies on the conducting nanocomposite prepared by in situ polymerization of aniline monomers in a neat (aqueous) synthetic mica clay

The in situ polymerization of the anilinium‐intercalated synthetic mica clay can easily result in an intercalated polyaniline (PANI)/clay nanocomposite. The FT‐IR spectra demonstrated a significant shift for ν_{(C? N)} at 1292 cm^?1 of the templated polymerized and intercalated PANI molecules. A red shift of λ_max for PANI was found from UV–vis spectra. The intercalated PANI also expanded the clay basal spacing seen from WAXD patterns. The degradation rate and temperature of the nanocomposites were found to alleviate and increase compared to neat PANI, respectively. The microscopic examinations including TEM, SEM, and AFM pictures of the nanocomposite demonstrated an entirely different and more compatible morphology. Conductivity of nanocomposite gradually increased with PANI and apparent increase was found when intercalated PANI content reached 40.6 wt %, the possible percolation threshold. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1800–1809, 2008     

Investigation of Nanoscopic Free Volume and Interfacial Interaction in an Epoxy Resin/Modified Clay Nanocomposite Using Positron Annihilation Spectroscopy

Epoxy/clay nanocomposites are synthesized using clay modified with the organic modifier N,N‐dimethyl benzyl hydrogenated tallow quaternary ammonium salt (Cloisite 10A). The purpose is to investigate the influence of the clay concentration on the nanostructure, mainly on the free‐volume properties and the interfacial interactions, of the epoxy/clay nanocomposite. Nanocomposites having 1, 3, 5 and 7.5 wt. % clay concentrations are prepared using the solvent‐casting method. The dispersion of clay silicate layers and the morphologies of the fractured surfaces in the nanocomposites are studied using X‐ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The observed XRD patterns reveal an exfoliated clay structure in the nanocomposite with the lowest clay concentration (≤1 wt. %). The ortho‐positronium lifetime (τ₃), a measure of the free‐volume size, as well as the fractional free volume (f_v) are seen to decrease in the nanocomposites as compared to pristine epoxy. The intensity of free positron annihilation (I₂), an index of the epoxy–clay interaction, decreases with the addition of clay (1 wt. %) but increases linearly at higher clay concentrations. Positron age‐momentum correlation measurements are also carried out to elucidate the positron/positronium states in pristine epoxy and in the nanocomposites. The results suggest that in the case of the nanocomposite with the studied lowest clay concentration (1 wt. %), free positrons are primarily localized in the epoxy–clay interfaces, whereas at higher clay concentrations, annihilation takes place from the intercalated clay layers.     

Study of the catalytic behavior of montmorillonite/iron(III) and Mn(III) cationic porphyrins

Two samples of montmorillonite (one of Brazilian origin, BNC1 clay, and the other STX-1, supplied by the Clay Mineral Society Repository (University of Missouri, USA) were allowed to react with biomimetic metalloporphyrins of Fe(III) and Mn(III) in cationic form. The compounds were characterized by several techniques, showing that the metalloporphyrins molecules were adsorbed at the surface of the clay platelet crystals. The catalytic activities of the intercalated complexes for the oxidation of alkane were dependent upon the concentration of the porphyrin immobilized in the clay and factors such as the metal ion species in the porphyrins, choice of solvent, and concentration of the iodosylbenzene oxidant. Good selectivity to cyclohexanol instead of cyclohexanone was observed for the catalytic oxidation of cyclohexane by iodosylbenzene.     

Heterogeneous reactions of gaseous HNO3 and NO2 on the clay minerals kaolinite and pyrophyllite

Airborne clay mineral particles have long atmospheric lifetimes due to their relatively small size. To assess their impact on trace atmospheric gases, we investigated heterogeneous reactions on prototype clay minerals. Diffuse reflectance infrared spectroscopy identified surface-adsorbed products formed from the uptake of gaseous nitric acid and nitrogen dioxide on kaolinite and pyrophyllite. For kaolinite, a 1:1 phyllosilicate, HNO3 molecularly adsorbed onto the octahedral aluminum hydroxide and tetrahedral silicon oxide surfaces. Also detected on the aluminum hydroxide surface were irreversibly adsorbed monodentate, bidentate, bridged, and water-coordinated nitrate species as well as surface-adsorbed water. Similar adsorbed products formed during the uptake of NO2 on kaolinite at relative humidity (RH) of 0%, and the reaction was second order with respect to reactive surface sites and 1.5 +/- 0.1 for NO2. Reactive uptake coefficients, calculated using Brunauer, Emmett, and Teller surface areas, increased from (8.0 +/- 0.2) x 10(-8) to (2.3 +/- 0.4) x 10(-7) for NO2 concentrations ranging from 0.56 x 10(13) to 8.8 x 10(13) molecules cm(-3). UV-visible spectroscopy detected gaseous HONO as a product for the reaction of NO2 on wet kaolinite. The uptake of HNO3 on pyrophyllite, a 2:1 phyllosilicate, resulted in stronger signal for nitric acid molecularly adsorbed on the silicon oxide surface compared to kaolinite. Monodentate, bridged, and water-coordinated nitrate species bound to aluminum sites also formed during this reaction indicating that reactive sites on edge facets are important for this system. The uptake of NO2 on pyrophyllite, gammaBET = (7 +/- 1) x 10(-9), was significantly lower than kaolinite because NO2 did not react with the dominant tetrahedral silicon oxide surface. These results highlight general trends regarding the reactivity of tetrahedral silicon oxide and octahedral aluminum hydroxide clay surfaces and indicate that the heterogeneous chemistry of clay aerosols varies with mineralogy and cannot be predicted by elemental analysis.     

Gas-phase Meerwein reaction of epoxides with protonated acetonitrile generated by atmospheric pressure ionizations

Ethylnitrilium ion can be generated by protonation of acetonitrile (when used as the LC-MS mobile phase) under the conditions of atmospheric pressure ionizations, including electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) as well as atmospheric pressure photoionization (APPI). Ethylnitrilium ion ( CH₃ - C o \mathop N⁺ HCH_3 - C \equiv \mathop N\limits^ + H and its canonical form CH₃ - \mathop C⁺ = NHCH_3 - \mathop C\limits^ + = NH) is shown to efficiently undergo the gas-phase Meerwein reaction with epoxides. This reaction proceeds by the initial formation of an oxonium ion followed by three-to-five-membered ring expansion via an intramolecular nucleophilic attack to yield the Meerwein reaction products. The density functional theory (DFT) calculations at the B3LYP/6-311 + G(d,p) level show that the gas-phase Meerwein reaction is thermodynamically favorable. Collision-induced dissociation (CID) of the Meerwein reaction products yields the net oxygen-by-nitrogen replacement of epoxides with a characteristic mass shift of 1 Da, providing evidence for the cyclic nature of the gas-phase Meerwein reaction products. The gas-phase Meerwein reaction offers a novel and fast LC-MS approach for the direct analysis of epoxides that might be of genotoxic concern during drug development. Understanding and utilizing this unique gas-phase ion/molecule reaction, the sensitivity and selectivity for quantitation of epoxides can be enhanced.     

Use of marker ion and cationic surfactant plastic membrane electrode for potentiometric titration of cationic polyelectrolytes

A plasticized poly (vinyl chloride) (PVC) membrane electrode sensitive to stearyltrimethylammonium (STA) ion is applied to the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by potentiometric titration, using a potassium poly (vinyl sulfate) (PVSK) solution as a titrant. The end-point of the titration is detected as the potential change of the plasticized PVC membrane electrode caused by decrease in the concentration of STA ion added to the sample solution as a marker ion due to the ion association reaction between the STA ion and PVSK. The effects of the concentration of STA ion, coexisting electrolytes in the sample solution and pH of the sample on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 2×10⁻⁵ to 4×10⁻⁴ N for Cat-floc, glycol chitosan, and methylglycol chitosan.     

Confinement and controlled release of quinine on chitosan–montmorillonite bionanocomposites

To accomplish the controlled‐release systems based on layered clay minerals, one of the best ways is to intercalate organic molecules into the interlayer gallery of clay minerals. Into a series of chitosan (CS) intercalated montmorillonite (MMT) nanocomposites, prepared via ion‐exchange route, antimalarial drug [quinine (QUI)] was loaded to act as effective drug delivery systems. Among the CS–MMT nanocomposites, higher drug adsorption with decreasing CS concentration was observed. CS–MMT and CS–MMT/QUI intercalated compounds were characterized by powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis. The synthesized nanocomposites, filled in the gelatin capsules followed by coating of Eudragit® L 100, were tested for in vitro drug release performance in the sequential buffer environments at 37 ± 0.5 °C. As no drug release (0%) was observed in the gastric fluid, the coating of Eudragit® L 100 to the capsules is highly adequate. However, the drug release rate was comparatively faster from the CS intercalated clay with compare with pure clay. The drug release kinetic data revealed that the release of QUI from the nanocomposites can be explained by modified Freundlich model. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation and properties of aramid/layered silicate nanocomposites by solution intercalation technique

Polymer—clay nanocomposites were synthesized from aromatic polyamide and organoclay using the solution intercalation technique. Polyamide chains were produced through the reaction of 4,4′‐oxydianiline (ODA) and isophthaloyl chloride (IPC) in N, N′‐dimethyl acetamide, using stoichiometry yielding chains with carbonyl chloride end groups. The intercalation of sodium montmorillonite (Na‐MMT) was carried out using p‐phenylene diamine as a swelling agent through an ion exchange reaction. Different concentrations of organoclay were blended with the polyamide solution for complete dispersion of clay throughout the matrix. The resulting composite films were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), mechanical testing, thermogravimetry (TGA), differential scanning calorimetry (DSC) and water absorption measurements. The XRD pattern and morphology of the nanocomposites revealed the formation of exfoliated and intercalated clay platelets in the matrix. The film containing a small amount of clay was semitransparent and had a tensile strength of the order of 70 MPa (relative to the 52 MPa of the pure aramid). Thermal decomposition temperatures were in the range of 300–450°C and the weight of the samples remaining after heating to 900°C was found to be roughly proportional to the clay loading. DSC showed a systematic increase in the glass transition temperature with increase in clay content. Water absorption of the pristine aramid film was rather high (5.7%), which reduced upon loading of organoclay. Copyright © 2008 John Wiley & Sons, Ltd.