Solvent Intercalation Research Articles

Effects of the electrolyte content on the electrical permittivity, thermal stability, and optical dispersion of poly(vinyl alcohol)–cesium copper oxide–lithium perchlorate nanocomposite solid‐polymer electrolytes

ABSTRACTSolid‐polymer electrolytes (SPEs) in the form of poly(vinyl alcohol) (PVA) doped with various amounts (5, 10, and 15 wt %) of lithium perchlorate trihydrate (LiClO4·3H2O) and 2 wt % cesium copper oxide (Cs2CuO2) nanoparticles were fabricated by a solvent intercalation method. The obtained nanocomposites were evaluated for their chemical structure and microstructural and morphological behaviors via Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy methods, respectively. The obtained dielectric behaviors, alternating‐current conductivity, dielectric modulus, and dielectric relaxation of the SPEs depended on the volume fraction of the electrolyte. Linear behavior of the current–voltage characteristics for all of the SPE films was observed with a slight deviation at a higher voltage. The thermal behaviors of the PVA–Cs2CuO2–LiClO4 films were evaluated by differential scanning calorimetry and thermogravimetric analysis. The refractive index, band‐gap energy, and optical dispersion were examined with UV–visible spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45852.

Elucidating the Key Role of a Lewis Base Solvent in the Formation of Perovskite Films Fabricated from the Lewis Adduct Approach.

High-quality perovskite films can be fabricated from Lewis acid-base adducts through molecule exchange. Substantial work is needed to fully understand the formation mechanism of the perovskite films, which helps to further improve their quality. Here, we study the formation of CH3NH3PbI3 perovskite films by introducing some dimethylacetamide into the PbI2/N,N-dimethylformamide solution. We reveal that there are three key processes during the formation of perovskite films through the Lewis acid-base adduct approach: molecule intercalation of solvent into the PbI2 lattice, molecule exchange between the solvent and CH3NH3I, and dissolution-recrystallization of the perovskite grains during annealing. The Lewis base solvents play multiple functions in the above processes. The properties of the solvent, including Lewis basicity and boiling point, play key roles in forming smooth perovskite films with large grains. We also provide some rules for choosing Lewis base additives to prepare high-quality perovskite films through the Lewis adduct approach.

Atomically Thin Layers of Graphene and Hexagonal Boron Nitride Made by Solvent Exfoliation of Their Phosphoric Acid Intercalation Compounds.

The development of scalable and reliable techniques for the production of the atomically thin layers of graphene and hexagonal boron nitride (h-BN) in bulk quantities could make these materials a powerful platform for devices and composites that impact a wide variety of technologies (Nature 2012, 490, 192-200). To date a number of practical exfoliation methods have been reported that are based on sonicating or stirring powdered graphite or h-BN in common solvents. However, the products of these experiments consist mainly of few-layer sheets and contain only a small fraction of monolayers. A possible reason for this is that splitting the crystals into monolayers starts from solvent intercalation, which must overcome the substantial interlayer cohesive energy (120-720 mJ/m2) of the van der Waals solids. Here we show that the yield of the atomically thin layers can be increased to near unity when stage-1 intercalation compounds of phosphoric acid are used as starting materials. The exfoliation to predominantly monolayers was achieved by stirring them in medium polarity organic solvents that can form hydrogen bonds. The exfoliation process does not disrupt the sp2 π-system of graphene and is gentle enough to allow the preparation of graphene and h-BN monolayers that are tens of microns in their lateral dimensions.

Extension of the Highly Mobile Membrane Mimetic to Transmembrane Systems through Customized in Silico Solvents.

The mechanics of the protein-lipid interactions of transmembrane proteins are difficult to capture with conventional atomic molecular dynamics, due to the slow lateral diffusion of lipids restricting sampling to states near the initial membrane configuration. The highly mobile membrane mimetic (HMMM) model accelerates lipid dynamics by modeling the acyl tails nearest to the membrane center as a fluid organic solvent while maintaining an atomic description of the lipid headgroups and short acyl tails. The HMMM has been applied to many peripheral protein systems; however, the organic solvent used to date caused deformations in transmembrane proteins by intercalating into the protein and disrupting interactions between individual side chains. We ameliorate the effect of the solvent on transmembrane protein structure through the development of two new in silico Lennard-Jones solvents. The parameters for the new solvents were determined through an extensive parameter search in order to match the bulk properties of alkanes in a highly simplified model. Using these new solvents, we substantially improve the insertion free energy profiles of 10 protein side chain analogues across the entire bilayer. In addition, we reduce the intercalation of solvent into transmembrane systems, resulting in native-like transmembrane protein structures from five different topological classes within a HMMM bilayer. The parametrization of the solvents, in addition to their computed physical properties, is discussed. By combining high lipid lateral diffusion with intact transmembrane proteins, we foresee the developed solvents being useful to efficiently identify membrane composition inhomogeneities and lipid binding caused by the presence of membrane proteins.

Crystallization of HC(NH2)2PbI3 Black Polymorph by Solvent Intercalation for Low Temperature Solution Processing of Perovskite Solar Cells

One of the critical problems in fabrication of flexible perovskite modules and resolving their reliability issue remains the necessity to utilize high temperature annealing for synthesis of perovskite and electron transport layers. Here, we provide a breakthrough in addressing these challenges by demonstrating low temperature synthesis of both of these layers. HC(NH)2PbI3 (commonly known as FAPbI3) has two polymorphs, a high temperature-stable black FAPbI3 perovskite-type pseudocubic polymorph (α-phase) and a low temperature-stable yellow non-perovskite hexagonal polymorph (δ-phase). In order to understand the crystallization kinetics of the FAPbI3 black polymorph, a PbI2-NMP complex is fabricated via solvent intercalation between the adjacent I-Pb-I layers. Utilizing structural, electrical, and thermal analyses, the connection between solvent intercalation and the crystallization of the FAPbI3 black polymorph is established. It is found that the solvent intercalation in the PbI2 crystal causes lattice st...

Effect of C70 rotation on the photoluminescence spectra of compressed C70*mesitylene

The efficient photoluminescence (PL) emission of solvated fullerenes has attracted significant interest because of their potential applications. Uncovering the possible factors that govern the PL emission of solvated fullerenes thus becomes important for the purpose of application. Here, we report a high pressure study on a typical solvated fullerene, C70*mesitylene, using the diamond anvil cell technique with associated spectroscopic measurements. Our Raman and PL spectra show that there is a change in the pressure dependence for the normalized PL intensity in solvated samples during the rotational transition. It indicates that the rotational state of C70 is a critical factor which can influence the PL emission of solvated samples. The optical absorption (OA) spectra further suggest that the C70–C70 interactions in solvated samples compared with those in desolvated samples are hindered under pressure because of the intercalation of solvent, which makes the PL emission in solvated samples more sensitive to the change in C70 rotations under pressure. Copyright © 2016 John Wiley & Sons, Ltd.

Preparation, adhesion and barrier properties of bituminous composite coatings on steel 37

A series of bitumen/nano clay nanocomposite have been prepared through solvent intercalation technique by using mechanical agitation and sonication process. The structure of nanocomposite coatings was investigated by TEM, low angle X-ray diffraction and Fourier-transform infrared spectroscopy. To investigate barrier properties of nanocomposite coatings, polarization, salt fog test and pull-off adhesion tests have been employed. The results showed that bitumen/MMT nanocomposite coatings were superior to the pristine bitumen coating in corrosion protection effects. Also, it was observed that the corrosion protection of bitumen/clay nanocomposite coatings improved as the clay loading is increased up to 4 wt.%

Cycling Performance and Interfacial Phenomena of High-Energy Li-Ion Battery with Sulfur-Based Cathode and Silicon-Based Anode

Li-ion battery market is currently expanding from small, portable batteries to electric vehicles and energy storage systems. To meet the demands, more than doubled energy density than that of currently used batteries is required. The energy density of current batteries, which consist of lithium metal oxide cathode and graphite anode materials, is however limited. A general approach to increase the energy density of a battery is the replacement of current cathode and anode active materials to higher capacity materials, and electrolyte that is interfacially compatible to them. Recently, sulfur-based cathode and silicon-based anode materials are considered as one of the most promising active materials for high-energy batteries. Earlier reports on sulfur-based cathode and silicon composite anode in half-cells showed a good cycling performance.1,2 However, there are just a few reports on the full-cell with those materials.3,4 To date, the best performance of full-cell was obtained when being assembled with carbon composite of elemental sulfur cathode, lithiated nanosphere Si/SiOx anode and a polysulfide-containing electrolyte, showing the capacity of 750 mAhg-1 and capacity retention of 85 % at the 500th cycle.3 However, the combination of sulfur-based cathode and silicon-based composite anode in a full-cell face several common issues such as the lack of Li+ source of sulfur cathode, solvent intercalation into graphite anode, and possible interfacial reaction between anode and soluble polysulfide formed during cycling. To overcome those issues, researchers have used Li2S instead of sulfur, fabricated anode with functional binder to prevent solvent intercalation, and modified electrolyte with polysulfide additive.3-5 However, interfacial reaction behavior in full-cells is unknown. In this study, we demonstrate good cycling performance of a full-cell composed of a new micron-sized sulfur-based cathode material and submicron-sized lithiated silicon-based anode material. Correlation between the cycling performance and interfacial phenomena would be discussed in the meeting. Acknowledgements This work was supported under the framework of international cooperation program managed by National Research Foundation of Korea (2015K2A5A3000068) and German Academic Exchange Service (57141898), and by the Ministry of Trade, Industry & Energy (10049609) of Korea, and Nano-Material Technology Development Program by the Ministry of Science, ICT and Future Planning (2009-0082580) of Korea.

Solvation, exchange and electrochemical intercalation properties of disodium 2,5-(dianilino)terephthalate

The development of intercalation chemistry in the early 70s has particularly enabled the deployment of novel and efficient electrode materials for electrochemical storage. A striking example is the commercialization of the first lithium-ion (rocking-chair) battery in 1991. Recently, a resurgence of new intercalation structures has occurred with the development of sodium-ion batteries, and therefore materials able to reversibly accommodate sodium ions in layered or porous solids (e.g., 3d transition-metal oxides). However, not only metal cations can be incorporated into multi-dimensional structures but also polar molecules and anions especially in 2-D host lattices where they can be accommodated through chemical or electrochemical reactions, respectively. Herein, we specifically report on disodium 2,5-(dianilino)terephthalate as a multifunctional organic intercalation material able to chemically exchange metal cations and accommodate organic polar molecules as well as host anions under electrochemical charging conditions. Powder X-ray diffraction measurements coupled with other analytical techniques were performed for evidencing the Na/Li exchange reaction as well as the solvent intercalation. Moreover, galvanostatic cycling tests and impedance spectroscopy measurements were performed to demonstrate the occurrence of anion intercalation process and the resulting effect on the conductivity of the analogous dilithium 2,5-(dianilino)terephthalate compound.

Controlling the properties of graphene produced by electrochemical exfoliation

The synthesis of graphene with controllable electronic and mechanical characteristics is of significant importance for its application in various fields ranging from drug delivery to energy storage. Electrochemical exfoliation of graphite has yielded graphene with widely varying behavior and could be a suitable approach. Currently, however the limited understanding of the exfoliation process obstructs targeted modification of graphene properties. We here investigate the process of electrochemical exfoliation and the impact of its parameters on the produced graphene. Using in situ optical and electrical measurements we determine that solvent intercalation is the required first step and the degree of intercalation controls the thickness of the exfoliated graphene. Electrochemical decomposition of water into gas bubbles causes the expansion of graphite and controls the functionalization and lateral size of the exfoliated graphene. Both process steps proceed at different time scales and can be individually addressed through application of pulsed voltages. The potential of the presented approach was demonstrated by improving the performance of graphene-based transparent conductors by 30times.

HIGHLY IMPERMEABLE NANOCOMPOSITES OF BROMINATED BUTYL RUBBER WITH MODIFIED MONTMORILLONITE CLAY

ABSTRACT Incorporation of nanoclays in vulcanized rubber can enhance the barrier and mechanical properties, with the aid of intercalation, exfoliation, or both. Achieving a high degree of dispersion such as intercalation and exfoliation is critical for obtaining optimal properties. In this work, a stepwise approach was developed to disperse the natural montmorillonite (MMT) clay modified with a quaternary ammonium salt in brominated butyl rubber (BIIR). The solvent intercalation method followed by mechanical shear was used to effectively intercalate/exfoliate the MMT bundles. Special consideration was given to effectively remove the solvent from the solvent intercalated master batch. The nanocomposites fabricated using this technique showed a high degree of intercalation and exfoliation along with improved barrier, dynamic mechanical, and mechanical properties. This improvement in properties offers an opportunity for this material to be used in high-end applications requiring improved mechanical as well as barrier properties; an example is a thinner tire inner liner with reduced hysteresis, lower running temperatures, and reduced fuel consumption.

Pressure-induced transformation and superhard phase in fullerenes: The effect of solvent intercalation

We studied the behavior of solvated and desolvated C60 crystals under pressure by in situ Raman spectroscopy. The pressure-induced bonding change and structural transformation of C60s are similar in the two samples, both undergoing deformation and amorphization. Nevertheless, the high pressure phases of solvated C60 can indent diamond anvils while that of desolvated C60s cannot. Further experiments suggest that the solvents in the solvated C60 act as both spacers and bridges by forming covalent bonds with neighbors in 3D network at high pressure, and thus, a fraction of fullerenes may preserve the periodic arrangement in spite of their amorphization.

Substrate-Induced Solvent Intercalation for Stable Graphene Doping

Here, we report a substrate-induced intercalation phenomenon of an organic solvent at the interface between monolayer graphene and a target substrate. A simple dipping of the transferred chemical vapor deposition (CVD)-grown graphene on the SiO₂ substrate into chloroform (CHCl₃, CF), a common organic solvent, induces a spontaneous formation of CF clusters beneath the basal plane of the graphene as well as inside the wrinkles. The microscopic and spectroscopic observations showed the doping behavior of monolayer graphene, which indicates the adsorption of CF to monolayer graphene. Interestingly, the intercalated organic solvent showed remarkable stability for over 40 days under ambient conditions. To reveal the underlying mechanism of the stable solvent intercalation, desorption energy of CF molecules at the graphene/substrate interface was measured using Arrhenius plots of the conductance change upon time and temperature. Two stages of solvent intercalations with high desorption energies (70 and 370 meV) were observed along with the consecutive shrinkage of the solvent clusters at the basal plane and the wrinkles, respectively. Moreover, the theoretical calculation based on density functional theory (DFT) also shows the strong intercalation energy of CF between monolayer graphene and the SiO₂ substrate, which results from the stabilization of the graphene-SiO₂ interactions. Furthermore, the thermal response of the conductance could be utilized to maintain a certain degree of p-doping of monolayer graphene, which provides the facile, sustainable, and controllable large-area doping method of graphene for future generation of printed flexible electronics.

Preparation and evaluation of polymer/clay nanocomposite surface treatments for concrete durability enhancement

In this work, the effectiveness of nanocomposite surface treatments as protective systems for concrete substrates was evaluated. The study was carried out on hybrid organic–inorganic systems prepared by solvent intercalation of an organomodified montmorillonite into two commercial resins: a coating and a pore liner. The obtained nanocomposite systems at 2, 4 and 6 wt% of nanoclay were applied on concrete substrates and characterized to evaluate their protection performances in comparison with the plain resins. In particular, the effect of the different treatments on liquid and vapor water barrier properties, salt attack resistance, porosity, surfaces water repellency and color changes were analyzed. The results demonstrated that the nanoclay addition can significantly improve the protection effectiveness of both the used plain resins, with chromatic modifications undetectable to the naked eye. However, the extent of the obtained gain strongly depends on the chemical nature and therefore on the mechanisms of action of the matrix.

THE ROLE OF CLAY IN ELECTRO-RESPONSIVE SMART POLYMER NANOCOMPOSITE MATERIALS

Smart nanocomposites of the conducting polymers such as polyaniline and polypyrrole with clay were investigated especially for electro-responsive electrorheological (ER) materials. These conducting polymer/clay nanocomposites were prepared via either in-situ polymerization, emulsion polymerization or solvent intercalation as well as pickering emulsion. Internal structure and thermal properties of these nanocomposites were examined via XRD, TEM, and thermogravimetric analyzer. Moreover, their ER behaviors were measured via a rotational rheometer with an external electric field controller. ER fluids based on different conducting polymer/clay nanocomposites demonstrated diverse ER characteristics such as yield stress and flow curve. Typical models were also used to investigate the rheological behaviors of the polymer/clay based ER fluid.

Phase transition of conducting polymer/clay nanocomposite suspensions under an electric field

Nanocomposites of conducting polyaniline and poly(o-ethoxyaniline) with clay were synthesized via emulsion polymerization and solvent intercalation, respectively, and then applied for electrorheological (ER) materials under an applied electric field. The morphology and intercalated nanostructures were analyzed via TEM images and XRD spectra. The ER performances of synthesized conducting polymer/clay nanocomposites-based ER fluids dispersed in silicone oil were investigated, exhibiting both electric field-dependent shear stress and yield stress. A suggested Cho–Choi–Jhon model was further employed to describe the shear stress curves.

Synthesis and Characterization of Aliphatic-aromatic Random Copolyester/clay Nano-biocomposites

Aliphatic-aromatic biodegradable random copolyester, poly (butylene sebacate-co-butylene isophthalate) (PBSeI) was synthesized by a two step direct melt polycondensation method. This copolyester was characterized by solubility studies, viscosity measurements, infrared, 1H-NMR, 13C-NMR and thermal data. However, to be a real alternative to classical synthetic polymers and find applications, the thermal properties of biodegradable polymers have to be improved. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to create polymers with characteristic properties. In the present study, the nano-biocomposites were synthesized by dispersing different weight percentages (1, 3 and 5%) of organo-modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by the solvent intercalation method. Structural characterization and thermal analysis were carried out to better understand, the relationship between the structuring of the nanofillers and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of the OMMT-clay in the polyester networks. The scanning electron microscopy and high resolution transmission electron microscopy analyses showed that there was no phase separation between the two components which confirmed the compatibility of polyester with the organo-modified clay system. The results show that clay incorporation improved the thermal properties of PBSeI due to the exfoliated structure of the nanocomposites formed, and thus may increase the applicability of this biodegradable polymer in different fields.

Permanent adsorption of organic solvents in graphite oxide and its effect on the thermal exfoliation

The dispersion of graphite oxide (GO) in organic solvents followed by their evaporation at relative high temperature resulted in a strong adsorption of the solvent molecules in the graphitic interlayers as confirmed by 13C magic-angle-spinning NMR. Three series of solvents, alcohols (1-methanol, 1-propanol, 1-pentanol, 1-heptanol), aromatics (benzene, toluene, p-xylene, chlorobenzene) and chloride compounds (dichloromethane, chloroform, carbon tetrachloride) were studied to understand the interaction of graphite oxide with solvents. The distribution of basal interlayer spacing changed due to solvent intercalation and this distribution was particularly different for each solvent series. Even though there was on average 1 solvent molecule per 100 carbon atoms of GO, they had a profound effect on the thermal properties of the resulting GO. The exfoliation temperature was drastically reduced by the presence of the solvents due to the increase of the interlayer spacing and the reducing power of the solvent.

Intercalation of solvent and polymer in galleries of mobile clay platelets by a Monte Carlo simulation

AbstractThe intercalation of solvent particles and polymer chains of concentration Cw = 0.2 and Cp = 0.2, respectively, in a layer of (4) clay platelets is studied by a Monte Carlo simulation on a cubic lattice. Polymer chains and platelets are modeled by bond fluctuations. Besides the excluded volume, a set of polymer‐clay (cs) and solvent‐clay (ws) interactions with (i) cs = 1, ws = −2, (ii) cs = −2, ws = 1 and (iii) cs = ws = −2 are considered. The global dynamics of platelets is constrained due to the presence of three components, i.e., solvent, polymer, and platelets, which retain their interstitial spacing with well‐defined galleries. Intercalation of solvent particles and polymer chains (low molecular weight) occurs with their attractive interaction with the platelets, which further reinforces the layered clay morphology. The density profiles of the solvent particles are similar to previous studies with platelets in a mobile solvent. The density profile of polymer chains differs considerably from the platelets in a polymer matrix alone, particularly with its attractive interaction (ii). For the same attractive interaction of solvent and polymer chains with the clay platelets (iii), the solvent particles (the smallest constituents) intercalate the fastest in the clay galleries, whereas the intercalation of polymer chains decreases with their molecular weight. The polymer density profiles, both longitudinal (x) and transverse (y), show maxima peaks around outer platelets (surface) of the layer and decay sharply both in the adjacent galleries and in the bulk. The amplitude of oscillation in the transverse density profiles, a measure of the degree of intercalation, decreases with increasing molecular weight of the polymer. The intercalation of the polymer is driven by its attractive interaction at the low molecular weight, but reduces considerably at high molecular weight because of both entanglement and larger radius of gyration. Variations of the gyration radius of the diffusing polymer chains with molecular weight and interaction with the clay are consistent with the results of their corresponding density profiles. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2487–2500, 2009

Studies on aliphatic -aromatic random copolyester- based nano-biocomposite materials

Aliphatic-aromatic biodegradable random copolyester, poly (butylene succinate-co-butylene isophthalate) PBSI was synthesised by a two step direct melt polycondensation method. This copolyester was characterised by solubility, viscosity measurements, IR, 1 H NMR, 13 C NMR and thermal studies. But, to be a real alternative to classical synthetic polymers and find applications, biodegradable polymer properties have to be enhanced. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to achieve the polymers with characteristic property. In present study, the nano- biocomposites were synthesised by dispersing different weight percentage (1, 3 and 5 %) of organo modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by solvent intercalation method. The structural characterisation and thermal analysis have been carried out to understand better the relationship between the nanofillers structuring and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of OMMT-clay in the polyester networks. The results show that the clay incorporation and the obtained structures enhanced the thermal properties of PBSI, and thus may increase the applicability of this biodegradable polymer in different fields.