Solution Intercalation Research Articles

Phase Change Materials (PCMs) Based in Paraffin/Synthetic Saponite Used as Heat Storage Composites

Synthetic saponites were successfully used to prepare phase change materials (PCMs) based on paraffin/synthetic saponite. Paraffin/synthetic saponites PCMs were prepared by a solution intercalation process. The PCMs were characterized by powder X-ray diffraction, FT-IR spectroscopy, thermal analyses and nitrogen adsorption. The thermal properties and the stability of PCMs were measured by DSC analysis and from heating–cooling curves. The results showed that the prepared PCMs have a higher heating rate and a lower cooling speed than paraffin because the heat storage was improved with the synthetic saponite. A one-pot synthesis method for obtaining PCM has been successfully developed in this work. The material thus obtained had better results for heat storage applications.

Polyvinylpyrrolidone/Montmorillonite/Zinc Oxide Bionanosystems Prepared by Spray Drying

In this study, microparticles of bionanomaterials were obtained by polyvinylpyrrolidone, montmoril-lonite, and zinc oxide bionanosystems produced through solution intercalation technique combined with a spray-drying process, aiming for possible application as drug delivery systems. The final microparticles obtained were evaluated in terms of their production yield, which varies between 39.2% and 56.9%. Thermal analysis showed no major changes in Tg of the nanocomposites, compared to the pure PVP polymer. Scanning electron microscopy analysis revealed a pseudo-spherical shape and confirmed the micrometric size of the microparticles. Transmission electron microscopy analysis corroborated the embedding of montmorillonite and ZnO within the polymer phase. Nuclear magnetic resonance and X-rays diffraction were used to study the nanoparticles dispersion, indicating a predominant intercalated morphology. This study suggests that the applied methodology is suitable for the high yields synthesis of nanocomposites PVP based microparticles with uniform size and shape, which can be promising for the production of a new drug delivery system.

Comparison of Properties of Colorless and Transparent Polyimide Nanocomposites Containing Different Diamine Monomers.

To improve the optical properties of polyimide (PI) films, we prepared two series of colorless transparent PIs from the dianhydride 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and a diamine, either 2,2-bis(3-aminophenyl)hexafluoropropane (FDN) or 2,2-bis(3-amino-4-hydroxy-phenyl)hexafluoropropane (FDN-OH). Next, colorless PI (CPI) composite films were prepared by dispersing 0–1.00 wt % of organically modified clay (Cloisite 30B) in the intermediate poly(amic acid) (PAA) solution via solution intercalation, followed by imidization. The resultant CPI films had excellent optical transparency, which was achieved by reducing the charge-transfer effects by using a highly electronegative trifluoromethyl group and a kinked monomer structure. The thermal and mechanical properties, morphologies, and optical transparencies of the two as-synthesized CPI hybrid film series were investigated and compared. Electron microscopy observation of the two hybrid series revealed that the clay was well-dispersed with a nanoscale dispersion at all clay contents. However, agglomeration occurred at nanoclay loadings of 1.0 wt %. In addition, the effect of the presence of hydroxyl groups in the PI chain on various physical properties of the two CPI hybrids was also compared.

Adsorption performance of the polystyrene/montmorillonite composites: Effect of plasma treatment

Polystyrene/montmorillonite (PS/MMT) composite films with high adsorption activity were prepared via solution intercalation technique followed by treatment of composite films in low-pressure air plasma. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the impact of plasma on the elemental composition and morphology of the composite surface. It was revealed that plasma treatment of the PS/MMT composite led to an increase in wettability and adsorption performance. The removal kinetics of methylene blue dye from aqueous solutions was experimentally studied. It was determined that plasma processing of the composite resulted in a significant improvement of the MB adsorption process: the initial rate of the process increased by 4 times (from 1.2 × 10−8 to 4.8 × 10−8 mol/(g•min)). Adsorption kinetic curves are obeyed the pseudo-second order reaction equation.

Preparation of new enforcement polyamide nanocomposite filled by ternary layer double hydroxide and investigation of electrochemical activity, optical and thermal properties

Herein, we report synthesis and manipulation of new reinforced polyamide nanocomposites filled by modified ternary (Mg, Zn, Al) layered double hydroxide by a solution intercalation technique. First, a new optically and electrochemically active polyamide 5 containing a new combination of azobenzene unit, imine function, triphenylamine segment and pyridine moiety in the main chain was prepared by reaction of a newly dicarboxylic acid 3 and 2,6-diaminopyridine 4. Then, two resulting nanocomposites containing 3 and 6% of DLDH were prepared and structures, morphology, electrochemical activity, thermal and optically properties of them were investigated. Also, dye-modified ternary layered double hydroxide was obtained by a co-precipitation method. The π–π* transition related to trans azobenzene chromosphere showed a single absorption between 290 and 350 nm. The electrochemically active behavior of resulting films onto glassy carbon exhibited cyclic voltammetry peak at 0.5–0.9 V, which was enhanced by filling polymer matrix with modified DLDH. On the other hand, significant improvements at T5, T10 and char yields of resulting nanocomposites were observed as compared to the polymer.

Bare Conductive® role as filler in mechanical and electrical reinforcement of polyvinyl alcohol-based strain sensor

Polyvinyl alcohol (PVA) is a water-soluble polymer typically suited for food and biomedical applications. However, its non-conductive properties limit PVA potential as material in electronic or sensor-based devices. In order to enhance the electrical as well as mechanical properties of PVA, Bare Conductive ® (BC) paste was incorporated into PVA solution using solution intercalation method. It is discovered that the addition of BC could enhance the mechanical and electrical properties of PVA. The tensile test data showed that the presence of carbon black in BC had resulted in the tensile stress improvement at about 50-170 % as compared to that of the original value. On the other hand, the electrical conductivity of PVA/BC composite film at a higher wt% had demonstrated a significant increment in resistance/length ratio (1.86 kΩ/cm at 0.2 wt%BC).

Nanocomposites of polyimide with Various Modified LDHs: Synthesis, characterisation and towards improvement of, morphology, thermal stabilities, mechanical properties, gas permeation and gas selectivity

ABSTRACT Novel polyimide (PI) nanocomposite films were synthesised from diamine monomer (diamine 1B) and Pyromellitic dianhydride (PMDA) with various modified layered double hydroxides (LDHs) particles via solution intercalation polymerisation to poly(amic acid)s, followed by thermal imidization. Modified LDHs particles, including LDH-amino benzoate (M-LDHs) were prepared with the coprecipitation method. The intercalation of PI chains among the LDHs particles was examined using wide-angle X-ray diffraction (XRD) and electron microscopy (TEM) techniques. TEM photographs showed that most LDH layers were dispersed homogeneously into the matrix polymer on the nanoscale, although some particles of LDHs were agglomerated. Moreover, the addition of only a small amount of LDHs particles was enough to improve the thermal stabilities and mechanical properties of PI hybrid films. The thermo-optical properties were measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and ultraviolet-visible (UV–vis) spectrometry. As anticipated, though the gas permeability of pure gases, viz., He, N2, CH4 and CO2 exhibited decrease, it was not monotonous. A marked decrease in permeability of gases like CO2 and CH4, in comparison to relatively lower decrease in permeability of He was observed, especially at higher LDH loading. An increase in selectivity: α(He/CO2) and α(He/CH4), especially at higher LDH loading indicated the capability of nanocomposites to tune the selectivity favourably.

Novel bio-inspired three-dimensional nanocomposites based on montmorillonite and chitosan

In this study, inspired by nacre-like structural natural shells, novel three-dimensional (3D) nanocomposites based on natural nanoplatelets of montmorillonite (MMT) and polysaccharide of chitosan (CS) were prepared with solution intercalation and self-assembly process. The CS-intercalated-MMT nanoplatelets units acted as “bricks” and CS molecules acted as “mortar”, arranging in fairly well-ordered layered structure. With addition of glutaraldehyde (GA) and Pd2+ cations, synergistic toughening and strengthening effects of covalent and ionic bonds could be achieved. The best mechanical properties of the prepared 3D nanocomposites were observed as 5.6 KJ/m2 (impact strength), 3.3 GPa (flexural modulus), and 65.8 MPa (flexural strength), respectively, which showed higher toughness but lower flexural properties than natural pearl mussel shells. Nevertheless, both the impact and flexural properties of the prepared 3D nanocomposite were much higher than the other natural shell, i.e. green grab shell. Besides conventional methods characterizations, the nacre-like structure of the artificial 3D nanocomposite was further evidenced with positron annihilation lifetime spectroscopy characterizations. This work might facilitate a versatile platform for developing green 3D bionanocomposites with fairly good mechanical properties.

Preparation and characterization of dicarboxylic acid modified starch-clay composites as carriers for pesticide delivery

Modified starch based composites were prepared with bentonite/organobentonite for their potential use as carriers for pesticide delivery. Soluble starch was esterified with dicarboxylic acid chlorides. Mean degree of substitution of modified starches varied from 0.101 to 0.353. Composites were prepared by solution intercalation method using these esterified starches and bentonite or cetyltrimethylammonium bentonite as filler materials. TEM analysis of composites showed well exfoliated/intercalated structures. Atrazine as a model pesticide was encapsulated in them and encapsulation was found to be 83.52–92.83%. These composites were also found to be acted as controlled release matrices for atrazine and release pattern was diffusion controlled. As compared to the commercially available wettable powder formulation, the composites were able to release encapsulated atrazine in water for a longer period. The research showed that the prepared composites could be further investigated as carriers for controlled release formulations of pesticides to minimize dose and number of applications.

Significant effect of base assisted intercalates in synthesis of 2D semiconductor Ti3C2O2

Theoretical chemists have predicted that Ti2CO2 and Ti3C2O2 possess an indirect bandgap that causes them to transform into semiconductors. However, few experiments have reported the appropriate bandgap for Ti3C2O2 and Ti2CO2. In this study, we first proved that Ti3C2O2 is a semiconductor by using a base-assisted intercalation method. A comprehensive study, including spectroscopy measurements, a computational approach, and mechanism analysis, established the efficacy of using a base. Results showed that Ti3C2O2 with a bandgap of 0.66 eV can be easily obtained after low-temperature annealing by using a novel base-assisted intercalation method. By contrast, such compound was hardly obtained when a solution intercalation procedure was used. The significant effect of the base was demonstrated in the synthesis procedure and the mechanism. The theoretical calculation predicted that Ti3C2O2 is a semiconductor with an indirect bandgap of 0.63 eV from the generalized gradient approximation. This prediction is consistent with the experimentally determined value.

Effect of ethylene carbonate on properties of PVP-CsAlO2-LiClO4 solid polymer electrolytes

ABSTRACT Solid polymer electrolytes (SPEs) have been widely studied due to its extensive applications in high energy rechargeable batteries, supercapacitors, fuel cells, photoelectrochemical and electrochromic displays. Herein, SPEs based on polyvinyl pyrrolidone (PVP) doped with cesium aluminate (CsAlO2) nanoparticles (NPs), lithium perchlorate (LiClO4) as an electrolyte and varying amounts viz., 2, 4, 6 and 8 wt.% of ethylene carbonate (EC) as plasticizer have been fabricated by solution intercalation technique. The structural features of PVP-CsAlO2-LiClO4-EC SPEs have been studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The morphology of PVP-CsAlO2-LiClO4-EC SPEs has been examined by scanning electron microscopy (SEM). The thermal properties of the SPEs were characterized by the thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC) techniques. The TGA and DSC results revealed that a significant reduction in thermal stability and glass transition temperature (Tg) of PVP with an increase in EC content in SPE films. The optoelectrical properties of PVP-CsAlO2-LiClO4-EC SPE films have been evaluated using UV–visible spectroscopy. The band gap energy (Eg) was found to decrease with an increase in EC content, exhibiting a minimum of 4.23 eV for PVP-8 wt.% CsAlO2-15 wt.% LiClO4-8 wt.% EC. This could be ascribed to the formation of localized states and increased degree of disorder in the PVP-CsAlO2-LiClO4 SPE films. The integrated plasticizers increase the values of refractive index (RI), optical conductivity, and dielectric constants of PVP-CsAlO2-LiClO4 SPE films. The AC conductivity of the SPEs has been evaluated at room temperature using digital LCR meter in the frequency range 100 Hz – 5 MHz. The conductivity strongly depends on CsAlO2 NPs and EC plasticizer content in SPEs.

Highly-performing and low-cost nanostructured membranes based on Polysulfone and layered doubled hydroxide for high-temperature proton exchange membrane fuel cells

The low cost, reduced fuel crossover and ease of preparation make sulfonated Polysulfone (sPSU) a potential candidate to replace Nafion electrolyte in proton exchange membrane fuel cells (PEMFCs). To reach a satisfactory proton conductivity the general strategy involves the preparation of macromolecules with high ion exchange capacity (IEC), even at the cost of sacrificing their mechanical properties. In this study, sPSU with relatively low IEC was used as polymer matrix for the preparation of nanocomposite electrolytes by dispersing Mg/Al–NO3- Layered Double Hydroxides (LDH). sPSU-LDH membranes were prepared by solution intercalation method and characterized by XRD, TGA and DMA, whereas water dynamics and proton conductivity were investigated by NMR (PFG and T1) and EIS spectroscopies, respectively. The complete exfoliation and nanodispersion of the LDH platelets into the polymer enhance the thermo-mechanical resistance, the dimensional stability and the water retention capacity of the electrolytes. The formation of highly connected ion channels promotes an effective Ghrotthus-type mechanism for the proton transport also under dehydrating environment. Such features allowed proton conductivity values and electrochemical performances in single cell PEMFC distinctly higher than the Nafion recast, demonstrating the possibility to prepare cost-effective and high performing sPSU-based membranes able to operate under low-humidification and high temperatures conditions.

Performance of nano-K-doped zirconate on modified opto-electrical and electrochemical properties of gelatin biopolymer nanocomposites

Nanocomposite (NC) films based on biopolymer gelatin incorporated with varying amounts of K-doped zirconate (K2ZrO3) nanoparticles (NPs) have been fabricated by solution intercalation technique. NPs obtained by combustion method and their TEM result revealed the average size of NPs is 18 nm ± 2. The effects of NPs content on structural and morphological behaviors of gelatin nanocomposite (NCs) have been established by XRD, FTIR and SEM methods. AC conductivity (σ) was performed using LCR meter. The σ increases with an increase in frequency and dosage of NPs where the maximum σ obtained is 5.73 × 10–5 S/cm for gelatin/4 wt% K2ZrO3 at 25 °C. Cyclic voltammetry data displayed that gelatin–K2ZrO3 NCs have electrochemical stability in the range – 0.5 to + 1 V. Charge–discharge data exhibited a higher specific capacitance of 26.5 F/g with higher discharge time for NC doped with 4 wt% K2ZrO3 as compared to pure gelatin. The optical behaviors of NCs were deduced by UV–visible (UV) spectroscopy, where the data showed a higher absorption intensity with increasing NPs, while band gap energy was reduced from 4.18 eV for pure gelatin to 2.91 eV for gelatin/4 wt% K2ZrO3. Swelling and contact angle data showed gelatin NC films tend to be less wettability as compared to pure gelatin.

Thermal Conductivity Enhancement in Polymer-Clay Nanocomposite Using Casting Techniques

Nowadays, there is a need for efficiency and miniaturization in electronic products. However, in the chip level, heat dissipation can limit the performance of these gadgets. Semiconductor industries addressed this thermal management challenge by using thermal interface material. Previous studies have shown that polymer-clay nanocomposite has an enhanced thermal conductivity which can be used as a thermal interface material. In this study, the aim was to determine the effect of casting techniques on the microstructure and thermal conductivity of the polymer-clay nanocomposites. Solution intercalation method was used in fabricating the 5vol% polymer-clay nanocomposite. Organo-modified montmorillonite (MMT) was dispersed in unsaturated polyester (UP) matrix by means of high frequency ultrasonication and formed using two casting techniques; mold casting and tape casting. Results showed a slight increase in the thermal conductivity coefficient of the tape-casted samples at 2.99 W/m-K compared to the mold-casted samples at 2.87 W/m-K. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) results exhibited dispersed microstructure for both casting techniques. Polymer intercalation of ~16% increase in d-spacing of clay for mold-casted samples and with a ~20% increase in d-spacing of clay for tape-casted samples were observed. With these microstructure modifications, the increase in the thermal conductivity coefficient of the tape-casted samples can be attributed to the shear force employed by the tape casting technique.

Highly selective SPEEK/ENR blended polymer electrolyte membranes for direct methanol fuel cell

Sulfonated poly (ether ether ketone) (SPEEK) at higher degrees of sulfonation (DS) produced high proton conductivity, but it is impractical for DMFC application due to excessive swelling and severe methanol crossover. In this study, a novel blended membrane based on SPEEK at higher degrees of sulfonation (DS) of 80% and epoxidized natural rubber (ENR-50) are prepared at different mass ratio of SPEEK to ENR-50 (9.5:0.5, 9.0:1.0, 8.5:1.5, 8.0:2.0, and 7.5:2.5) via solution intercalation method. The influence of ENR-50 loading on the physical properties of SPEEK blends membranes was investigated and compared with the pristine SPEEK and Nafion117 membranes. The blended membranes were characterized by FTIR, which showed a successful chemical interaction between ENR-50 and SPEEK matrix. SEM images revealed a uniform dispersion of ENR-50 droplets in the polymer structure. The water uptake and methanol permeability of SPE50 membrane were found to be decreased with increasing of ENR-50 content. The highest proton conductivity of SPE50 membrane obtained was 47% higher than pure SPEEK, whereas the lowest permeability value obtained was 21 times lower than Nafion117 membrane. Consequently, incorporation of ENR-50 into SPEEK matrix has substantially enhanced the selectivity of the membrane by five folds. Apparently, this newly developed SPE blend membrane can be listed as one of the potential proton electrolyte membranes for the usage in DMFCs.

A Review on Barrier Properties of Poly(Lactic Acid)/Clay Nanocomposites.

Poly(lactic acid) (PLA) is considered to be among the best biopolymer substitutes for the existing petroleum-based polymers in the field of food packaging owing to its renewability, biodegradability, non-toxicity and mechanical properties. However, PLA displays only moderate barrier properties to gases, vapors and organic compounds, which can limit its application as a packaging material. Hence, it becomes essential to understand the mass transport properties of PLA and address the transport challenges. Significant improvements in the barrier properties can be achieved by incorporating two-dimensional clay nanofillers, the planes of which create tortuosity to the diffusing molecules, thereby increasing the effective length of the diffusion path. This article reviews the literature on barrier properties of PLA/clay nanocomposites. The important PLA/clay nanocomposite preparation techniques, such as solution intercalation, melt processing and in situ polymerization, are outlined followed by an extensive account of barrier performance of nanocomposites drawn from the literature. Fundamentals of mass transport phenomena and the factors affecting mass transport are also presented. Furthermore, mathematical models that have been proposed/used to predict the permeability in polymer/clay nanocomposites are reviewed and the extent to which the models are validated in PLA/clay composites is discussed.

Preparation of Chitosan Graft Polyacrylic Acid/Graphite Oxide Composite and the Study of its Adsorption Properties of Cationic Dyes

Chitosan-graft-polyacrylic acid/graphite oxide (CTS-g-PAA/GO) superabsorbent composite was prepared by solution intercalation graft copolymerization of chitosan (CTS), acrylic acid and graphite oxide (GO). The composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscope, thermogravimetric analysis and differential scanning calorimetry. Adsorption properties of cationic dyes such as rhodamine 6G (R6G) and methyl violet (MV) onto the composite were studied in detail. It was found that small amount of GO (0.02 g) can improve the adsorption capacities of dyes significantly. The interactions between GO and dye molecules are discussed. For R6G,there are both hydrogen bonds and the electrostatic interactions between CTS-g-PAA/GO composite and dye molecules, while for MV, there are only electrostatic interactions. The adsorption isotherms and kinetics were also studied. It was shown that adsorption of R6G was in accordance with the Langmuir isotherm equation, while that of MV met both the Langmuir and Freundlich equations. The adsorption kinetic of R6G and MV both were in accordance with the pseudo-second-order kinetic model.

Study on a novel poly (vinyl alcohol)/graphene oxide-citicoline sodium-lanthanum wound dressing: Biocompatibility, bioactivity, antimicrobial activity, and wound healing effect

Although graphene oxide (GO) is widely used as an antibacterial agent, its efficacy still needs to be improved. In this work, we present a novel medical dressing that improves antibacterial effect and promotes wound healing. Poly (vinyl alcohol)/graphene oxide-citicoline sodium-lanthanum (PVA/GO-CDPC-La) films were prepared by the solution intercalation method for usage in wound dressing applications. GO was modified by zwitterionic citicoline (CDPC) to improve the dispersibility of water-based polymers, while providing La3+ ions with more adsorption sites and enhancing the antibacterial properties of the film. Water absorption experiments showed that it could effectively absorb wound exudate while keeping the wound moist. In vitro cytotoxicity and cell adhesion experiments showed that the PVA/GO-CDPC-La films acknowlhad good biocompatible and promoted wound healing. Bacterial adhesion experiments showed PVA/GO-CDPC-La could greatly reduce the risk of wound infection. Furthermore, in vivo wound healing experiments showed that wounds treated with the film healed faster postoperatively and histological observations showed that a mature epidermal architecture was formed, which could be used as a wound-dressing material.

Enhanced performance of Mindel membranes by incorporating conductive polymer and inorganic modifier for application in direct methanol fuel cells

AbstractSulfonated polyethersulfone (SPES), polyaniline (PANI), and Cloisite 15 A® were used as modifiers for the fabrication of Mindel composite polymer electrolyte membranes (PEMs). Pristine Mindel and Mindel composite PEMs were fabricated by the solution intercalation technique. The presence of modifiers in the Mindel membrane matrix was confirmed by Fourier transform infrared (FTIR) studies. The primary characteristics of pristine Mindel and Mindel PEMs such as water uptake, methanol uptake, proton conductivity ion‐exchange capacity (IEC), and chemical and mechanical stability were evaluated. The pore size of Mindel/SPES/Cloisite 15 composite PEM was increased owing to the addition of SPES and Cloisite 15. The higher proton conductivity of 4.323 × 10−4 S cm−1, enhanced IEC of 0.482 mequiv. g−1, and maximum water uptake (%) of 38.12 were noted for Mindel/SPES/Cloisite membrane. Membrane selectivity of all Mindel PEMs was enhanced by the addition of modifiers. The results of this study indicate that Mindel composite membranes could be utilized as PEMs for direct methanol fuel cell (DMFC).

Multi-adaptability supercapacitor electrolyte based on Na-MMT/PDADMAC and application in wide temperature range

Polyelectrolyte is widely used in supercapacitors, but its poor matching with electrodes and narrow operating temperature range limit its further application. Here, Na-Montmorillonite/Poly dimethyl diallyl ammonium chloride (Na-MMT/PDADMAC) composite polyelectrolyte was prepared by solution intercalation and assembled into solid supercapacitor with three different electrodes (carbon, NiCo(OH)2 and Polypyrrole electrode). The result shows that Na-MMT/PDADMAC polyelectrolyte has a good matching performance with the three kinds of electrode. After 1000 cycles at 15℃, 35℃ and 50℃, the capacitance of all electrodes basically remain above 90%, showing wide operating temperature range. More interestingly, with the increase of Na-MMT, the combustion resistance of Na-MMT/PDADMAC solid polyelectrolyte film gradually increases, and the maximum flame resistance time can reach 50 s, indicating that the solid electrolyte film has good heat resistance. The good matching and wide temperature adaptation range with electrodes are mainly attributed to the addition of Na-MMT, which not only increases the ion migration rate, but also limits the thermal decomposition of PDADMAC molecular chain.