Intercalation Rate Research Articles

Development of Poma/Ptaa Layer-By-Layer Films As Active Material for Electrochromic Devices

Besides those need concerning the energy conversion and storage, there are many different forms to save energy in the modern society. Among then, the use of smart windows which control the amount of light in modern buildings has become an important issue in the last years. Besides, the same kind of devices, in a different configuration, are used, for many years, as rear drive mirror in automobiles. A large class of optically active materials have been proposed to be applied in electrochromic windows, and among them, conducting polymers are a promising choice. These materials change their color upon reversible electrochemical redox cycles, which changes also their electronic properties, such as electronic conductivity. Coupled to the electronic redox reactions, there are ion intercalation (deintercalation) to compensate the generated charges and which are described as the slow step during the redox reaction. As consequence, there are several papers in the literature aiming at to optimize the redox reaction rate to improve the electrochromic device properties. In the present work, we investigate the electrochromic properties of layer-by-layer poly(o-methoxyaniline)-poly(3-thiophene acetic acid), POMA/PTAA, films and compare then with POMA films prepared by casting. The main technique used to characterize the materials has been the potentiostatic steps, between -0.2 V and 0.5 V, and collecting both, the current density and the optical density, measured at 700 nm, during the experiments. The results have shown that the changes in the optical densities for the LBL POMA/PTAA films are larger than those observed in POMA casting ones. Besides, the rate of the change is faster for the LBL material. In this last sense, the optical density change period has been 1 s for the pure POMA film while it is 0.4 s for the LBL one. A second effect is that, considering the same charge, there is a variation of 26 % in the transmittance for POMA film while it is 46 % for the LBL POMA/PTAA one. A third important effect is an increase of the change in the optical density as the number of bilayers is increased for the LBL films. Unexpected, for pure POMA sample, there is a decrease in the optical change as the film mass is increased. Probably, this last effect is a consequence of the decrease in the ion intercalation rate or even a deactivation of the deep portion of the film, under the experimental conditions used during the potentiostatic step. As described above, LBL film presents a different behavior. It is described in previous papers that this material, LBL POMA/PTAA, present self-doping effect. In this sense the ion intercalation total amount decreases significantly due to the self-doping effect which means an interaction between H+ and COO- groups in the PTAA polymer, and the amine (or imine) groups in POMA chains. Finally, there is an important increase in the optical and electrochemical results upon continuous cycling. Under this condition, the LBL film remains optically and electrochemically stable for at least 3000 cycles.

Dissecting the Dynamic Pathways of Stereoselective DNA Threading Intercalation

DNA intercalators that have high affinity and slow kinetics are developed for potential DNA-targeted therapeutics. Although many natural intercalators contain multiple chiral subunits, only intercalators with a single chiral unit have been quantitatively probed. Dumbbell-shaped DNA threading intercalators represent the next order of structural complexity relative to simple intercalators, and can provide significant insights into the stereoselectivity of DNA-ligand intercalation. We investigated DNA threading intercalation by binuclear ruthenium complex [μ-dppzip(phen)4Ru2]4+ (Piz). Four Piz stereoisomers are defined by the chirality of the intercalating subunit (Ru(phen)2dppz) and the distal subunit (Ru(phen)2ip), respectively, each of which can be either right-handed (Δ) or left-handed (Λ). We used optical tweezers to measure single DNA molecule elongation due to threading intercalation, revealing force-dependent DNA intercalation rates and equilibrium dissociation constants. The force spectroscopy analysis provided the zero-force DNA binding affinity, the equilibrium DNA-ligand elongation Δxeq, and the dynamic DNA structural deformations during ligand association xon and dissociation xoff. We found that Piz stereoisomers exhibit over 20-fold differences in DNA binding affinity, from a Kd of 27 ± 3 nM for (Δ,Λ)-Piz to a Kd of 622 ± 55 nM for (Λ,Δ)-Piz. The striking affinity decrease is correlated with increasing Δxeq from 0.30 ± 0.02 to 0.48 ± 0.02 nm and xon from 0.25 ± 0.01 to 0.46 ± 0.02 nm, but limited xoff changes. Notably, the affinity and threading kinetics is 10-fold enhanced for right-handed intercalating subunits, and 2- to 5-fold enhanced for left-handed distal subunits. These findings demonstrate sterically dispersed transition pathways and robust DNA structural recognition of chiral intercalators, which are critical for optimizing DNA binding affinity and kinetics.

Soft X-ray Exposure Promotes Na Intercalation in Graphene Grown on Si-Face SiC.

An investigation of how electron/photon beam exposures affect the intercalation rate of Na deposited on graphene prepared on Si-face SiC is presented. Focused radiation from a storage ring is used for soft X-ray exposures while the electron beam in a low energy electron microscope is utilized for electron exposures. The microscopy and core level spectroscopy data presented clearly show that the effect of soft X-ray exposure is significantly greater than of electron exposure, i.e., it produces a greater increase in the intercalation rate of Na. Heat transfer from the photoelectrons generated during soft X-ray exposure and by the electrons penetrating the sample during electron beam exposure is suggested to increase the local surface temperature and thus the intercalation rate. The estimated electron flux density is 50 times greater for soft X-ray exposure compared to electron exposure, which explains the larger increase in the intercalation rate from soft X-ray exposure. Effects occurring with time only at room temperature are found to be fairly slow, but detectable. The graphene quality, i.e., domain/grain size and homogeneity, was also observed to be an important factor since exposure-induced effects occurred more rapidly on a graphene sample prepared in situ compared to on a furnace grown sample.

The preparation of the hydrotalcite-based composite phase change material

MgAlCO3-Hydrotalcite (HT) was prepared via hydrothermal synthesis method in this paper. Then the HT was organically modified. The composite PCM was prepared with the organic HT and paraffin via the liquid intercalation. The interlayer groups of HT were investigated using a Fourier Transform Infrared Spectroscopy (FTIR) before and after modification. The microscopic structure of the organic HT/paraffin composite PCM was characterized using a Scanning Electron Microscope (SEM). The thermal properties were measured using a Differential Scanning Calorimeter (DSC) and a thermal constant analyzer. The results showed that the HT prepared via the hydrothermal synthesis had single crystal phase and high crystallinity. The layer spacing of the organic HT was expanded. The intercalation rate of paraffin was 25.9wt% in the organic HT. The phase transition temperature and the phase change enthalpy of the organic HT/paraffin composite PCM were 26.2°C and 29.8J/g, respectively.

Lithium Iron Phosphate Nanosheet Nests As Cathode Material for Li-Ion Batteries

Nano Electrochemistry Laboratory, College of Engineering, The University of Georgia, Athens, GA 30602. Lithium-ion batteries are the current state-of-the-art energy storage technology for advanced electric vehicles and portable power applications due to their high energy density. The need for low cost lithium ion batteries has driven the development of inexpensive LiFePO4 cathodes, which offer a relatively high specific capacity (170 mAh·g-1) and relatively high discharge potential plateau (3.45 V) at a fraction of the cost of other materials. In additional to the low electrical conductivity, one of the major drawbacks of this material is the inherently slow lithium diffusion. Unlike spinel or layered structures, the olivine structure of LiFePO4 allows lithium diffusion in only one direction and therefore severely limits the intercalation rate due to slow solid-state diffusion. This limitation could be overcome by de-sizing the material in the < 010 >, the direction of diffusion. This can be achieved by synthesizing LiFePO4 nanosheet nests (LFP-NSN) using a directed growth method adapted and modified from a synthesis procedure reported earlier.1 Figure 1 shows the scanning electron microscopy (SEM) image of the LFP-NSN synthesized by our modified procedure. Figure 2 shows the X-ray diffraction (XRD) pattern of the synthesized LFP-NSN, which compares well with the XRD pattern of orthorhombic, olivine-type LiFePO4 from the library. For battery testing, the synthesized structures were mixed in a ratio 80:10:10 of LFP-NSN: Super C carbon: poly(vinylidine fluoride) in N-methyl pyrrolidone to form a slurry that was cast on aluminum foil to be used as the cathode in CR2032 lithium ion coin cells for testing and evaluation. Fig. 1: a) SEM image and b) XRD pattern (black) with LiFePO4 characteristic peaks identified in red of LFP-NSN synthesized by a solvothermal reaction. Acknowledgements: The authors would like to thank Dr. Tina Salguero and Dr. Zhengwei Pan for their help in this project. * Corresponding Author: rama@uga.edu Reference: 1. Y. Zhao, L. Peng, B. Liu and G. Yu, Single-Crystalline LiFePO4 Nanosheets for High-Rate Li-Ion Batteries. Nano letters 2014, 14, 2849-2853. Figure 1

Enhanced electrochemical performance of mesoporous carbon with increased pore size and decreased pore wall thickness

As anode materials for Lithium-ion batteries, mesoporous materials such as mesoporous carbon can deliver high rate and stability on cycling owing to their unique mesostructure. Especially, the critical dimensions of pore size and wall thickness may highly influence the rate of intercalation. Herein a novel mesoporous carbon with increased pore size and decreased pore wall thickness is prepared by sacrificing Sn nanoparticles embedded in the carbon wall of CMK-3, and exhibits superior cycle and rate performances than normal CMK-3. Thus the structural parameters of mesoporous carbon are very important to its electrochemical performance and should be optimally controllable.

The Limited Effect of VC in Graphite / NMC Cells

Degradation at the electrode surfaces is one of the major reasons behind capacity fade in a well-constructed battery. The presence of electrolyte additives is known to alter the electrode particle surface which may in turn lead to changes in rates of intercalation as well as side-reactions. In particular, VC has been studied extensively for different lithium-ion chemistries and been shown to improve columbic efficiency of some electrodes. In the present study, the effect of vinylene carbonate (VC) as an electrolyte additive in a graphite/NMC 333 (lithium-nickel-manganese-cobalt oxide) cell is investigated. The study shows that the addition of VC improves the rate performance especially at moderately high rates. A new three-electrode cell design with Li as a reference electrode was used in this study. The three-electrode cell was particularly useful in studying the effect of VC on the rate performance of each electrode. The rate of side reactions is found to decrease with the addition of VC. Despite these important performance improvements, no significant improvement in the capacity retention is observed. This suggests that the side reactions in Gr./NCM cells consist of two types, those that go to repair cracked SEI on the anode and results in a net consumption of Li from the cathode and those that reform SEI components that dissolve from the anode and are oxidized at the cathode. The VC appears to reduce the second type but have negligible effect on the first. This also indicates that columbic efficiency measurements are not a reliable indicator of cell life with regard to short term capacity fade.

Intercalation Compounds from LiH and Graphite: Relative Stability of Metastable Stages and Thermodynamic Stability of Dilute Stage Id

The intercalation of lithium into graphite was studied at temperatures between 400 and 550 °C by heating mixtures of LiH and graphite powders with molar ratios 4:1, 1:1, and 1:6 under dynamic vacuum for periods between 1 and 72 h. These conditions probe the formation and thermal stability of metastable staged Li–graphite intercalation compounds (Li-GICs) close to the competing formation of the thermodynamically stable carbide Li2C2. Li-GICs of stages I (LiC6, Aα), IIa (Li0.5C6, AαA), IIb (Li∼0.33C6, AαABβB), III (Li∼0.22C6, AαAB), IV (Li∼0.167C6), and dilute stage lithium Id have been identified and characterized by powder X-ray diffraction and Raman spectroscopy. The rate and extent of intercalation (i.e., the achieved stage of Li-GIC) depends on LiH activity and temperature. Stage I was only observed for temperatures above 500 °C. At 400 °C, the highest intercalation corresponded to stage IIb, which was obtained after 2 and 24 h for 4:1 and 1:1 reaction mixtures, respectively. Lower-staged Li-GICs attained at temperatures below 500 °C deintercalate upon prolonged dwelling with the exception of stage IIa, which can be maintained for very long periods (several days) in the presence of LiH. At temperatures above 500 °C, the kinetically controlled formation of Li-GICs is followed by Li2C2 carbide formation. It is shown that the Li-GIC Id coexists with Li2C2 at temperatures up to 800 °C and that the Li content of Id (solubility of Li in graphite) increases between 550 and 800 °C. Consequently, Id with a temperature-dependent homogeneity range should be added as a stable phase in the Li–C phase diagram. A sketch of a revised Li–C phase diagram is provided.

Intercalation and retention of carbon dioxide in a smectite clay promoted by interlayer cations.

A good material for CO2 capture should possess some specific properties: (i) a large effective surface area with good adsorption capacity, (ii) selectivity for CO2, (iii) regeneration capacity with minimum energy input, allowing reutilization of the material for CO2 adsorption, and (iv) low cost and high environmental friendliness. Smectite clays are layered nanoporous materials that may be good candidates in this context. Here we report experiments which show that gaseous CO2 intercalates into the interlayer nano-space of smectite clay (synthetic fluorohectorite) at conditions close to ambient. The rate of intercalation, as well as the retention ability of CO2 was found to be strongly dependent on the type of the interlayer cation, which in the present case is Li+, Na+ or Ni2+. Interestingly, we observe that the smectite Li-fluorohectorite is able to retain CO2 up to a temperature of 35°C at ambient pressure, and that the captured CO2 can be released by heating above this temperature. Our estimates indicate that smectite clays, even with the standard cations analyzed here, can capture an amount of CO2 comparable to other materials studied in this context.

A molecular dynamics study of lithium grain boundary intercalation in graphite

Lithium-ion diffusion rates in graphitic battery anodes have been shown to vary greatly in experiments, with numerous hypotheses to explain this behavior. Here, we model several grain boundaries using molecular dynamics and quantify intercalation from the free surface. A significant variation in intercalation rates is revealed as dictated by local bond structure where the grain boundary intersects the free surface. Data presented may help explain dramatic differences in diffusion rates and permit more accurate predictions of lithium-ion battery performance.

Uveal melanoma cells utilize a novel route for transendothelial migration.

Uveal melanoma arises in the eye, and it spreads to distant organs in almost half of patients, leading to a fatal outcome. To metastasize, uveal melanoma cells must transmigrate into and out of the microvasculature, crossing the monolayer of endothelial cells that separates the vessel lumen from surrounding tissues. We investigated how human uveal melanoma cells cross the endothelial cell monolayer, using a cultured cell system with primary human endothelial cell monolayers on hydrogel substrates. We found that uveal melanoma cells transmigrate by a novel and unexpected mechanism. Uveal melanoma cells intercalate into the endothelial cell monolayer and flatten out, assuming a shape and geometry similar to those of endothelial cells in the monolayer. After an extended period of time in the intercalated state, the uveal melanoma cells round up and migrate underneath the monolayer. VCAM is present on endothelial cells, and anti-VCAM antibodies slowed the process of intercalation. Depletion of BAP1, a known suppressor of metastasis in patients, increased the amount of transmigration of uveal melanoma cells in transwell assays; but BAP1 depletion did not affect the rate of intercalation, based on movies of living cells. Our results reveal a novel route of transendothelial migration for uveal melanoma cells, and they provide insight into the mechanism by which loss of BAP1 promotes metastasis.

The dynamics of Fe intercalation on pure and nitrogen doped graphene grown on Pt(111) probed by CO adsorption

Abstract In this paper we compare by temperature programmed desorption the intercalation rate of Fe nanoparticles supported on pure and nitrogen doped graphene grown on Pt (111). Carbon monoxide desorption from Fe sites is used to probe the overall quantity of Fe present onto the graphene surface. We do not observe any appreciable difference of CO desorption temperature induced by N functionalities of graphene; however we notice a faster intercalation for Fe nanoparticles deposited on N-doped graphene with respect the those supported on pure graphene. We relate this phenomenon to nanoholes created by pyridinic and pyrrolic functionalities and/or to the lower bond enthalpy of C N with respect to C C bonds. Scanning tunneling microscopy and X-ray photoelectron spectroscopy are used as complementary techniques to identify the N functionalities and to characterize the morphological defectivity of the graphene films.

Long-term stability of fluorine–graphite intercalation compound prepared under high pressure of fluorine

Fluorine–graphite intercalation compounds were prepared from highly oriented pyrolytic graphite (HOPG) and natural graphite under high pressure of fluorine (16MPa) at room temperature and were analyzed by means of X-ray diffraction. The rate of intercalation under high pressure of fluorine was higher than that under ordinary pressure. The compositions of the compounds obtained from HOPG and natural graphite were estimated by the weight change before and after fluorination to be C3.41F and C5.62F, respectively. They were blue–black compounds composed of two different phases. One phase is a conventional stage II CxF with the repeat distance of ca. 0.93–0.96nm which was the same compound as that obtained under ordinary pressure of fluorine, and the other was also a stage II with a different repeat distance of ca. 1.03–1.18nm. The fluorine species intercalated between the graphene layers can easily move between both phases and the phase transition occurs periodically. The decomposition rate of fluorine-intercalated HOPG was extremely low and it shows a long-term stability in air for 26years.

Benzylamine-directed growth of olivine-type LiMPO4nanoplates by a supercritical ethanol process for lithium-ion batteries

Olivine-type LiMPO4 (M = Fe, Mn, Co and Ni) cathode materials hold promise for next-generation of lithium-ion batteries and future applications as hybrid electric vehicles or electric vehicles. In lithium intercalation olivine compounds, the lithium diffusion along a channel is highly anisotropic which is mainly confined to the channel along the [010] direction. Thus, nanosheets or nanoplates with shortened Li ion diffusion distance along the [010] direction are enabled to accelerate the lithium intercalation rate and improve power density of the batteries. Herein, we report the production of high-quality thin LiMPO4 nanoplates with exposed {010} facets by a rapid supercritical fluid processing. The unique structure of the olivine nanocrystals with a shortened Li ion diffusion pathway allows fast extraction/insertion of Li ions in the structures. Thus, the LiMPO4 nanoplates provide high capacity and high rate capacity and excellent cyclability.

Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study.

Different materials in form of sponge, hydrogel and film have been developed and formulated for treating and dressing burn wounds. In this study, the potential of Laponite, a gel forming clay, in combination with an antimicrobial agent (mafenide), as a wound dressing material was tested in vitro. Laponite/mafenide (Lap/Maf) hydrogel was formulated in three different ratios of Lap/Maf 1:1, 1:2, 1:3. Laponite/mafenide/alginate (Lap/Maf/Alg) film was also formulated by combining Lap/Maf gel (1:1) with alginate. Intercalation rate of mafenide into the layers of Laponite nanoparticles and physico-chemical properties, including wound dressing characteristics of materials were studied using various analytical methods. Furthermore, the degradation of materials and the release profile of mafenide were investigated in simulated wound exudates fluid and antibacterial effectiveness of the eluted mafenide was tested on a range of bacterial species. The cytotoxicity of materials was also evaluated in skin fibroblast culture. The results showed that mafenide molecules were intercalated between the nano-sized layers of Laponite. The eluted mafenide showed active antibacterial effects against all three tested bacteria. All intercalated mafenide released from Lap/Maf 1:1 and 1:2 gel formulations and nearly 80% release from 1:3 formulation during test period. No significant difference was observed in release profile of mafenide between Lap/Maf/Alg film and Lap/Maf formulations. Wound dressing tests on Lap/Maf/Alg film showed it is a breathable dressing and has capacity to absorb wound exudates. The study showed that prepared Lap/Maf composite has the potential to be used as an antibiotic eluting gel or film for wound healing application. Additionally, Laponite has shown benefits in wound healing processes by releasing Mg(2+) ions and thereby reducing the cytotoxic effect of mafenide on fibroblast cells.

Fabrication of nano serpentine-potassium acetate intercalation compound and its effect as additive on tribological properties of the fabric self-lubricating liner

The nano Serpentine-Potassium Acetate (Ser-KAc) organic intercalation compound was prepared by treating the nano-serpentine particles with potassium acetate through ultrasonication vibration. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry–thermogravimetry (DSC–TG), and X-ray diffractometry (XRD) were performed to study the effects of the ultrasonication power, ultrasonication time and intercalation temperature on the interlaminar spacing and intercalation rate of the compound. Remarkable intercalation effects were achieved under certain ultrasonication condition. Comparative studies on the tribological properties of the fabric self-lubricating liners with different concentrations of the nano-serpentine or nano Ser-KAc compound additives were conducted. It showed that addition of nano-serpentine or nano Ser-KAc compound improves the wear resistance of the liners to varying degrees but slightly decreases their antifriction performance in an applicative range. In this paper, a model of the unworn fabric self-lubricating liner modified with Ser-KAc compound were developed according to the experimental results. It was found that the liner with 2wt% nano Ser-KAc compound additive exhibited excellent tribological performances.

Enhancing the efficiency of lithium intercalation in carbon nanotube bundles using surface functional groups.

The effect of surface functionalization on the ability and kinetics of lithium intercalation in carbon nanotube (CNT) bundles has been studied by comparing the dynamical behaviors of lithium (Li) ions in pristine and -NH2 functionalized CNTs via ab initio molecular dynamics simulations. It was observed that lithium intercalation has been achieved quickly for both the pristine and surface functionalized CNT bundle. Our calculations demonstrated for the first time that CNT functionalization improved the efficiency of lithium intercalation significantly at both low and high Li ion density. Moreover, we found that keeping the nanotubes apart with an appropriate distance and charging the battery at a rational rate were beneficial to achieve a high rate of lithium intercalation. Besides, the calculated adsorption energy curves indicated that the potential wells in the system of -NH2 functionalized CNT were deeper than that of the pristine CNT bundle by 0.74 eV, and a third energy minimum with a value of 2.64 eV existed at the midpoint of the central axis of the nanotube. Thus, it would be more difficult to remove Li ions from the nanotube interior after surface functionalization. The barrier for lithium diffusion in the interior of the nanotube is greatly decreased because of the surface functional groups. Based on these results, we would suggest to "damage" the nanotube by introducing defects at its sidewall in order to improve not only the capacity of surface functionalized CNTs but also the efficiency of lithium intercalation and deintercalation processes. Our results presented here are helpful in understanding the mechanism of lithium intercalation into nanotube bundles, which may potentially be applied in the development of CNT based electrodes.

Theory of Chemical Kinetics and Charge Transfer based on Nonequilibrium Thermodynamics

Advances in the fields of catalysis and electrochemical energy conversion often involve nanoparticles, which can have kinetics surprisingly different from the bulk material. Classical theories of chemical kinetics assume independent reactions in dilute solutions, whose rates are determined by mean concentrations. In condensed matter, strong interactions alter chemical activities and create variations that can dramatically affect the reaction rate. The extreme case is that of a reaction coupled to a phase transformation, whose kinetics must depend not only on the order parameter but also on its gradients at phase boundaries. Reaction-driven phase transformations are common in electrochemistry, when charge transfer is accompanied by ion intercalation or deposition in a solid phase. Examples abound in Li-ion, metal-air, and lead-acid batteries, as well as metal electrodeposition-dissolution. Despite complex thermodynamics, however, the standard kinetic model is the Butler-Volmer equation, based on a dilute solution approximation. The Marcus theory of charge transfer likewise considers isolated reactants and neglects elastic stress, configurational entropy, and other nonidealities in condensed phases. The limitations of existing theories recently became apparent for the Li-ion battery material LixFePO4 (LFP). It has a strong tendency to separate into Li-rich and Li-poor solid phases, which scientists believe limits its performance. Chemists first modeled phase separation in LFP as an isotropic "shrinking core" within each particle, but experiments later revealed striped phase boundaries on the active crystal facet. This raised the question: What is the reaction rate at a surface undergoing a phase transformation? Meanwhile, dramatic rate enhancement was attained with LFP nanoparticles, and classical battery models could not predict the roles of phase separation and surface modification. In this Account, I present a general theory of chemical kinetics, developed over the past 7 years, which is capable of answering these questions. The reaction rate is a nonlinear function of the thermodynamic driving force, the free energy of reaction, expressed in terms of variational chemical potentials. The theory unifies and extends the Cahn-Hilliard and Allen-Cahn equations through a master equation for nonequilibrium chemical thermodynamics. For electrochemistry, I have also generalized both Marcus and Butler-Volmer kinetics for concentrated solutions and ionic solids. This new theory provides a quantitative description of LFP phase behavior. Concentration gradients and elastic coherency strain enhance the intercalation rate. At low currents, the charge-transfer rate is focused on exposed phase boundaries, which propagate as "intercalation waves", nucleated by surface wetting. Unexpectedly, homogeneous reactions are favored above a critical current and below a critical size, which helps to explain the rate capability of LFP nanoparticles. Contrary to other mechanisms, elevated temperatures and currents may enhance battery performance and lifetime by suppressing phase separation. The theory has also been extended to porous electrodes and could be used for battery engineering with multiphase active materials. More broadly, the theory describes nonequilibrium chemical systems at mesoscopic length and time scales, beyond the reach of molecular simulations and bulk continuum models. The reaction rate is consistently defined for inhomogeneous, nonequilibrium states, for example, with phase separation, large electric fields, or mechanical stresses. This research is also potentially applicable to fluid extraction from nanoporous solids, pattern formation in electrophoretic deposition, and electrochemical dynamics in biological cells.

Intercalation of cetyl trimethylammonium ion into sericite in the solvent of dimethyl sulfoxide

In order to improve the microenvironment between layers of sericite in the manufacture of polymer/sericite nanocomposites, a pre-modified sericite was intercalated by cetyl trimethylammonium ion (CTA+) in a dimetzhyl sulfoxide (DMSO) solvent. The relevant experimental conditions, such as intercalating time, temperature, solid content and pH value, were optimized, and the intercalated sericite was characterized by X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy analyses. At an intercalation rate of 94%, the amount of CTA+ intercalated in the interlayer space of sericite was 36.3% and an expansion of d001 value from 1.00nm to 5.07nm was observed. The intercalated CTA+ in the interlayer space of sericite adopted a paraffin-type bilayer configuration with a tilting angle of 53.6°. Due to its unique structure, DMSO would be better than water as the solvent for intercalation of organic cations. The intercalated sericite was more suitable to combine with polymer to form polymer/sericite nanocomposites.

ChemInform Abstract: Ordered Mesoporous Metal Oxides: Synthesis and Applications

AbstractReview: 237 refs.