Preparation of poly(propylene)/clay layered nanocomposites by melt intercalation from pristine montmorillonite (MMT)

Poly(propylene)/clay nanocomposites were prepared by melt intercalation, using pristine montmorillonite (MMT), hexadecyl trimethyl ammonium bromide (C16), poly(propylene) (PP) and maleic acid (MA) modified PP (MAPP), The nanocomposites structure is demonstrated using X‐ray diffraction (XRD) and high resolution electronic microscopy (HREM). Our purpose is to provide a general concept for manufacturing polymer nanocomposites by melt intercalation starting from the pristine MMT. We found different kneaders (twin‐screw extruder or twin‐roll mill) have influence on the morphology of the PP/clay nanocomposites. Thermogravimetric analysis (TGA) shows that the thermal stability of PP/clay nanocomposites has been improved compared with that of pure PP. Copyright © 2003 John Wiley & Sons, Ltd.     

The rhodamine B intercalation of montmorillonite

Using photometric methods the dissociation constants and weight fractions of rhodamine B dimer in water solutions at different concentrations were determined. The montmorillonite (SWy) samples were fully intercalated with rhodamine B (RhB) solutions at various monomer/dimer ratios. The amount of rhodamine B in fully intercalated montmorillonite (RhB-SWy) increases with increasing concentration of dye in water solutions, i.e., with increasing dimer/monomer ratio. The sum of exchangeable guest cations in RhB-SWy is approximately constant (0.900 meq g(-1)) for all samples, because RhB-SWy samples with prevailing dye monomer also contain higher amounts of non-exchanged alkali elements. The experimental data are supported by calculated structure models that illustrate the changes in RhB-SWy structure depending on monomeric and/or dimeric arrangement of guests. The analysis of the calculated structure models confirmed the existence of two phases with different basal spacings, d approximately 1.8 and approximately 2.3 nm, revealed by X-ray diffraction.     

Preparation of thermosetting polyurethane nanocomposites by montmorillonite modified with a novel intercalation agent

A novel thermosetting polyurethane (TSPU)/organic montmorillonite (OMMT) nanocomposite has been synthesized. N‐diamino octadecyl trimethyl ammonium chloride (DODTMAC) was used as an intercalation agent to treat Na⁺‐montmorillonite (MMT) and form a novel kind of OMMT. Fourier transform infrared spectroscopy (FT‐IR), wide angle X‐ray diffraction (WAXD), and thermogravimetric analysis (TGA) data indicated that the MMT was successfully intercalated by this intercalation agent, as evidenced by the fact that the basal spacing of MMT galleries was expanded from 1.5 to 3.2 nm. This OMMT was used to prepare the TSPU nanocomposites. Both the reinforcing and compatibilizing performance of the filler were investigated. Tensile tests showed that the tensile strength of TSPU/OMMT‐4 was the highest, and was about 3.62 times higher than that of the pure TSPU, and also the elongation at break showed an enhancement. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) measurements illustrated that the glass transition temperature of the TSPU/OMMT‐4 nanocomposite was improved from 0.5 to 6.5 °C, which corresponded to the restriction of the soft segments of TSPU. The highest initial and center temperatures of TSPU/OMMT‐4 obtained from TGA were due to the highest retard effect of the TSPU molecular chains. WAXD studies showed that the formation of the nanocomposites in all the cases with the almost disappearance of the peaks corresponding to the basal spacing of MMT. SEM and TEM were used to investigate the morphologies of the TSPU/OMMT‐4 nanocomposite, and demonstrated that the nanocomposite was comprised of a well dispersion of a mixture of intercalated and exfoliated silicate layers throughout the matrix. It was proposed that the nano‐reinforcing effect caused by the well‐dispersed silicate layers might reduce the amount and size of voids and increase the length of the crack‐spreading path during tensile drawing. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 519–531, 2007.     

Preparation and characterization of poly(propylene carbonate)/montmorillonite nanocomposites by solution intercalation

Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability and low glass transition temperatures (T_g) have limited its applications. To improve the thermal properties of PPC, organophilic montmorillonite (OMMT) was mixed with PPC by a solution intercalation method to produce nanocomposites. An intercalated-and-flocculated structure of PPC/OMMT nanocomposites was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal and mechanical properties of PPC/OMMT nanocomposites were investigated by thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), and electronic tensile tester. Due to the nanometer-sized dispersion of layered silicate in polymer matrix, PPC/OMMT nanocomposites exhibit improved thermal and mechanical properties than pure PPC. When the OMMT content is 4 wt%, the PPC/OMMT nanocomposite shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC.     

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.     

Swelling, intercalation, and exfoliation behavior of layered ruthenate derived from layered potassium ruthenate

The intercalation chemistry of a layered protonic ruthenate, H_0.2RuO_2.1·nH₂O, derived from a layered potassium ruthenate was studied in detail. Three phases with different hydration states were isolated, H_0.2RuO_2.1·nH₂O (n=0, 0.5, 0.9), and its reactivity with tetrabutylammonium ions (TBA⁺) was considered. The layered protonic ruthenate mono-hydrate readily reacted with TBA⁺, affording direct intercalation of bulky tetrabutylammonium ions into the interlayer gallery. Fine-tuning the reaction conditions allowed exfoliation of the layered ruthenate into elementary nanosheets and thereby a simplified one-step exfoliation was achieved. Microscopic observation by atomic force microscopy and transmission electron microscopy clearly showed the formation of unilamellar sheets with very high two-dimensional anisotropy, a thickness of only 1.3±0.1 nm. The nanosheets were characterized by two-dimensional crystallites with the oblique cell of a=0.5610(8) nm, b=0.5121(6) nm and γ=109.4(2)° on the basis of in-plane diffraction analysis.     

Thermal stability of methacrylamide/montmorillonite intercalation complex

Thermal stability of methacrylamide intercalated octadecylammonium montmorillonite (OD-M/MA) is limited by rapid desorption of methacrylamide (MA) at 140°C. It was improved by -irradiation. The irradiation intercalation complex OD-M/MA shows significant shift of the whole desorption process towards higher temperatures. However, part of the adsorbed organic material is released at 50°C signalizing presence of some volatile fractions. Decomposition products of the intercalated material and long-chain alkylamides in the acetone extract indicate complex reactions between MA and octadecylammonium chains. An additional swelling of the silicate structure occurs after -ray initiation and is probably related to the reaction products with a certain degree of cross-linking in the interlayers.     

基于胶束插层方法制备高热稳定性和大层间距有机化蒙脱土

采用不同方法制备了多种有机化蒙脱土,并分别采用X射线衍射仪、红外光谱分析仪、热重分析仪、电感耦合等离子体发射光谱仪、元素分析仪、扫描电子显微镜对产物进行了表征,并提出了有机物插层新方式——胶束插层.结果表明:适量钠基蒙脱土(Na-MMT)、十六烷基三甲基溴化铵(CTAB)和磷酸三苯酯(TPP)在丙酮/水的混合溶剂中进行溶液插层,得到的有机化蒙脱土具有更大的层间距,比单纯采用CTAB的插层效果显著.产物中含有约21.54%的CTAB和17.47±1.05%的TPP,插层机理为CTAB-TPP胶束插层.该有机化蒙脱土的初始热降解温度比单纯CTAB插层蒙脱土最多提高了17.4℃.采用该方法制备的改性蒙脱土既可以进一步提高蒙脱土的层间距,又可以封闭TPP于MMT的片层间,阻止TPP挥发;同时克服季铵盐改性蒙脱土的热稳定性低的问题,得到了层间距大、热稳定性高的有机化蒙脱土,为有机化蒙脱土在高熔点聚合物改性方面提供了条件.     

Melt intercalation of polystyrene in layered silicates

We have studied the melt intercalation of polystyrene into organically modified sodium bentonite, a layered, mica-type silicate, using a variety of techniques. Wide-angle X-ray scattering experiments on polymer/silicate hybrid samples demonstrate that intercalation of polymer chains leads to an ∼25% increase in the spacing between silicate layers. The magnitude of this increase, compared with the radius of gyration of the melt polymer, implies a flattened conformation of chains in the galleries. Low voltage scanning electron microscopy reveals voids in the intercalated hybrid matrix that correspond to regions where pristine polymer was present in the physical mixture of polymer and silicate before intercalation. Differential scanning calorimetry shows that only unintercalated polymer contributes to the measured glass transition trace, so that the magnitude of the trace is diminished upon intercalation. © 1996 John Wiley & Sons, Inc.     

Thermal properties of polystyrene nanocomposites formed from rigid intercalation agent‐treated montmorillonite

Polystyrene (PS)/clay nanocomposites were prepared with two different new intercalation organophilic clays, the phosphonium salt (APP) and the ammonium 4‐(4‐adamantylphenoxy)‐1‐butanamine (APB) salts, by emulsion polymerization technique. X‐ray diffraction and transmission electron microscopy were performed to characterize the layered structures of APB‐ and APP‐treated polymer–clay nanocomposites, and both resulted in exfoliated structures. Molecular weights of PS obtained from these nanocomposites are slightly lower than the virgin PS formed under similar polymerization conditions. Coefficient of thermal expansion showed approximately a 44–55% decrease for APB‐ and APP‐intercalated clay nanocomposites relative to the pure PS. Both T_g and thermal decomposition temperature of the PS component in the nanocomposite are higher than the virgin PS, implying that the presence of clay is able to enhance thermal stabilities of the PS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1781–1787, 2007     

Effect of the intercalation conditions of a montmorillonite with octadecylamine

Intercalation of montmorillonite with octadecylamine under several conditions is reported. Octadecylamine was protonated in situ with HCl to obtain octadecylammonium cations. Water and water/ethanol mixtures were used as reaction medium, and the ratios amine/clay and HCl/amine were also varied. Intercalation was successful when the amine/clay ratio was in the range 1-3 mmol/g; optimal results were obtained for an amine/clay ratio of 2.0 mmol/g. For a given amine/clay ratio, the HCl/amine ratio also influences the intercalation. Basal spacings of the intercalated solids were between 13.4-36.7 angstroms. The amount of organic matter incorporated into the solids also varied widely; up to 40 wt% is fixed. Specific surface area is very low in all the intercalated solids because of the blockage of the clay porosity by the organic molecules. Co-intercalation of octadecylammonium and of the inorganic polycation [Al13O4(OH)24(H2O)12]7+ was also considered, giving rise to intercalated solids with basal spacings between 17 and 22 A, also with a high fixation of organic matter.     

Effects of montmorillonite interlayer micro-circumstance on the PP melting intercalation

1-Octadecyl-3-methylimidazolium chloride ([C₁₈ mim]Cl) is a kind of imidazolium ionic liquid with high thermal stability. [C₁₈ mim]Cl was used to modify pristine Na-montmorillonite and a series of organo-montmorillonite (OMMT) with different loading levels of 1-octadecyl-3-methylimidazolium cation ([C₁₈ mim]⁺) were obtained. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) results show that there are different loading levels and aggregative state of [C₁₈ mim]⁺ in the interlayer of OMMT. The effects of OMMT interlayer micro-circumstances on the PP melting intercalation were studied by XRD and transmission electron microscopy (TEM). Results indicate that the melting intercalation of PP into the interlayer of OMMT is not only related with d-spaces but also has something to do with the interlayer micro-circumstance of OMMT. Based on these facts, three types of interlayer absorption models of [C₁₈ mim]⁺ in the interlayer of OMMT were conceived. In addition, the aggregative state of [C₁₈ min]⁺ in the interlayer of OMMT, interlayer polarity and d-spaces of OMMT were discussed. According to these models, we try to illustrate the effect of interlayer micro-circumstance of OMMT on the PP melting intercalation.     

Synthesis of co-containing aluminosilicates with a microporous layered columnar structure from montmorillonite clays

The conditions of synthesis of cobalt-containing aluminosilicates with a microporous layered columnar structure from montmorillonite clays were correlated with their texture characteristics. The main factors governing the texture properties of the material were shown to be the montmorillonite content in natural clay, the calcination temperature, and the type of hydrolyzing agent and OH^?: Me ⁿ⁺ ratio during the preparation of the modifying solution.     

Preparation of an intercalation compound of layered titanic acid H2Ti4O9 with methylene blue

Intercalation of methylene blue into layered titanic acid H₂Ti₄O₉ was examined by a guest exchange method using a propylammonium-H _x Ti₄O₉ intercalation compound as the intermediate. Methylene blue cations were arranged in the interlayer space obliquely to the layer surface. The visible spectrum of the intercalation compound suggested that the methylene blue cations were in an associated state in the interlayer space of H₂Ti₄₀₉. The intercalated methylene blue cations underwent a reversible electrochemical redox reaction in the dark, indicating that intercalation compounds of H₂Ti₄O₉ can be applied to a modified electrode.     

The intercalation of metalloporphyrin complex anions into layered double hydroxides

Investigations to elucidate the structures of the cobalt(III) and manganese(III) complexes of tetra(p-sulfonatophenyl)porphinate anions (M(III)TSPP; M = Co and Mn), intercalated in Mg-Fe/Cl and Mg-Al/Cl layered double hydroxides (LDHs) have been carried out. Powder X-ray diffraction analysis, IR and UV-vis diffuse reflectance spectroscopy of Co(III)TSPP and Mn(III)TSPP intercalated into the interlayer spaces of LDH resulted in their perpendicular alignment against the host layers in the plane of the hybrid.     

Interdigitation, interpenetration and intercalation in layered cuprous tricyanomethanide derivatives

Reaction of Cu(I), tricyanomethanide (tcm , C(CN)3-) and L = either hexamethylenetetramine (hmt), 4,4'-bipyridine (bipy) or 1,2-bis(4-pyridyl)ethene (bpe) gives crystals of [Cu(tcm)(hmt)] (1), [Cu(tcm)(bipy)] (2) and [Cu(tcm)(bpe)] x 0.25 bpe x 0.5 MeCN (3), respectively. Crystal structure analysis shows 1-3 all contain closely related puckered (4,4) sheets composed of tetrahedral Cu(I) ions bridged by 2-connecting tcm- and L. The crystal packing, however, varies markedly with L. In 1 the sheets interdigitate in pairs. In 2 the sheets participate in parallel interpenetration in pairs. In 3 guest bpe and MeCN molecules are intercalated in channels formed by the stacking of the sheets.     

The intercalation of transition metal salen complexes into layered MoS2

Exfoliation-restack method has been employed to synthesize the intercalation compounds based on the cationic complexes [M(Salen)]⁺ (M = Mn³⁺, Fe³⁺, Co³⁺; Salen = N, N′-ethylene-bis(salicylaldimine)) into the layered MoS₂. Their conductivity is in the range of 0.04–0.1 S/cm, which is much higher than the pristine MoS₂. Magnetic measurement indicated that the intercalation compounds [Mn(Salen)]_0.18MoS₂ · 0.25H₂O and [Fe(Salen)]_0.12MoS₂ · 0.3H₂O exhibit the temperature-dependent paramagnetism, which obviates from the Curie–Weiss law due to the temperature-independent paramagnetism of the exfoliated MoS₂ slabs, while [Co(Salen)]_0.14MoS₂ · 0.5H₂O exhibits the almost temperature-independent paramagnetism. All three intercalation compounds do not show magnetic spin crossover behavior.     

Reactions of metallocenes during intercalation into the layered TiSe2 lattice

The intercalation of metallocenes (Cp₂Co, Cp₂Fe, and Cp₂Ni, where Cp is η⁵-C₅H₅) from the gas phase into the TiSe₂ lattice and of cobaltocene from solutions in acetonitrile, carbon tetrachloride, and chloroform into TiSe₂ was studied. The insertion of metallocenes from the gas phase into the TiSe₂ lattice gives rise to the TiSe₂(Cp₂M)_0.3 compounds (M = Co or Fe) having the same stoichiometry. The reactions with the use of acetonitrile as the solvent for metallocenes, which facilitates the insertion, afford not only the intercalation complex but also the reaction product of metallocene and acetonitrile, viz., (η ⁵-C₅H₅)Co(η⁴-C₅H₅CH₂CN) (1). In the reactions of cobaltocene with chloroform or carbon tetrachloride in the presence of titanium diselenide, only the addition product, viz., (η ⁵-C₅H₅)Co(η₄-C₅H₅CCl₃) (2), was isolated. The structures of complexes 1 and 2 were studied by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 876–880, May, 2007.     

The intercalation of bicyclic and tricyclic carboxylates into layered double hydroxides

Twenty-four nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised for the first time. Eight carboxylates were successfully intercalated into [LiAl₂(OH)₆]Cl·yH₂O, [Ca₂Al(OH)₆]NO₃·yH₂O, and [Mg₂Al(OH)₆]NO₃·yH₂O, and the products fully characterised. Guest species incorporated include 1-adamantane carboxylate (1-AC) and 5-norbornene-2-endo-3-exo-dicarboxylate. In some cases, carbonate anions were co-intercalated with the organic guest, and in others poorly crystalline aluminium hydroxides formed as by-products. Sharper resonances were observed in the ¹³C solid-state NMR spectra of the 1-AC intercalates than in the spectrum of pure 1-AC, suggesting increased order in the arrangement of the cyclic cages in the intercalates. Where possible, time-resolved in situ X-ray diffraction was employed to study the nanoscopic steps involved in the intercalation reactions. These investigations showed that the reactions are one-step processes, proceeding directly to the fully exchanged intercalate with no intermediate phases. The intercalation processes were found to be nucleation controlled.