Α-zirconium Phosphate Research Articles

Effective Intercalation and Exfoliation of Nanoplatelets in Epoxy via Creation of Porous Pathways

A new surface modification approach for improving intercalation and exfoliation efficiency of layered nanoplatelets is introduced on the basis of α-zirconium phosphate (α-ZrP) nanoplatelets. The intercalation of α-ZrP nanoplatelets was carried out using a number of different organic surface modifiers and their combinations. It is found that porous pathways, which can be created by incorporating a combination of a linear long-chain amine and a bulky, short-chain amine as intercalating agents, can lead to speedier and more effective intercalation. Consequently, fully exfoliated polymer nanocomposites can be more easily prepared. The intercalation/exfoliation mechanisms accounting for the observed effectiveness are discussed.

Characteristics of Surfactant-Zirconium Phosphate Composites with Expanded Interlayer Separation

Surfactant-zirconium phosphate composites were prepared by surfactant cetyltrimethylammonium bromide intercalating to α-zirconium phosphate. The interlayer spacing of the lamellar structure was greatly expanded to 39.6 Å, as compared to 7.6 Å of α-zirconium phosphate. The molar ratio of surfactant to α-zirconium phosphate in the composites was found to be 1/1.46. The expanded interlayer separation is beneficial for complicated guest molecules intercalating to the galleries of the composites.

Studies on the preparation and structure of polyacrylamide/α-zirconium phosphate nanocomposites

In this paper, a novel polyacrylamide(PAM)/α-zirconium phosphate(α-ZrP) nanocomposite was successfully synthesized by exfoliation-adsorption and in-situ intercalative polymerization. The microstructure of PAM/α-ZrP nanocomposites was confirmed by X-ray diffraction measurement, transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM). The results suggested that the α-ZrP lamellae were dispersed well in PAM matrix, which indicated the formation of the exfoliated nanocomposites in the low inorganic loading of α-ZrP (≤5 wt%). With the increase of the inorganic loadings, the intercalated structure of PAM/α-ZrP nanocomposites was dominant with the d-spacings of about 1.50–1.58 nm corresponding to the inorganic loadings in the range of 10–20 wt%. Moreover, besides the electrostatic adsorption, it was also found that there may be some weak effect such as hydrogen bonding or protonation between the host and guest investigated using fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG )analysis, which resulted in the enhancement of the thermal properties on the decomposition process of PAM/α-ZrP nanocomposites by the retardant effect of the exfoliated or intercalated α-ZrP nanometer lamellae.

Preparation of Exfoliated Epoxy/α-Zirconium Phosphate Nanocomposites Containing High Aspect Ratio Nanoplatelets

High-crystallinity α-zirconium phosphate (α-ZrP) crystals which contain stacks of high aspect ratio nanoplatelets were synthesized and exfoliated with tetra-n-butylammonium hydroxide in aqueous dispersion. The exfoliated α-ZrP nanoplatelets were then transferred into water-miscible organic solvents, such as acetone, by centrifugation and re-dispersion. The resulting exfoliated α-ZrP nanoplatelets in organic solvents can be easily utilized to prepare polymer nanocomposites. Through such an approach, epoxy/α-ZrP nanocomposites containing high aspect ratio α-ZrP nanoplatelets have been prepared. The presence of the well-exfoliated nanocomposite structure is confirmed by powder X-ray diffraction and transmission electron microscopy.

Preparation of silylated α-zirconium phosphate and its thermal behavior

Porous zirconium phosphate was prepared by silylation with organic silanes. Octylamine was intercalated into α-Zr(HPO 4) 2·H 2O for expanding interlayer spacing and 1,2-bis(dimethylchlorosilyl)ethane (BMCE) was used for silylation of inorganic layers in toluene. The number of octhylamine molecules intercalated was similar to the number of phosphorus in the inorganic layers. On the other hand, that of BMCE molecule after silylating treatment was much smaller than that of phosphorus. The interlayer spacing of silylated compound was confirmed to expand via high-temperature XRD patterns and was preserved on thermal treatment up to around 500 °C. The maximum specific surface area of the silylated compound heated at 300 °C was around 70 m 2/g, though that was smaller for silylated compounds heated at higher and lower temperature.

Vibrational spectra and H-bondings in anhydrous and monohydrate α-Zr phosphates

A new FTIR and FT-Raman investigation on α-zirconium phosphate (Zr(HPO 4) 2·H 2O) and its anhydrous form has been performed in order to obtain an affordable assignment of their vibrational spectra as well as to highlight the hydrogen bonding structure formed by the P-OH groups and the intercalated water molecules. To this end the spectral changes induced by both temperature and isotopic exchange were observed on several high-purity grade samples of different morphology especially prepared and well characterized by SEM, RX, DSC and TGA. In particular, it is also presented as a detailed discussion of the results obtained by FTIR-PAS for different sample morphology. The observed spectra have been analyzed and interpreted according to the α-Zr(HPO 4) 2·H 2O crystal structure and H-bond geometry. The obtained results allowed to clarify the mechanism of the α-Zr(HPO 4) 2·H 2O→ α-Zr(HPO 4) 2 dehydration process as well as the H-bonding changes involved in the high temperature phase transition of anhydrous α-Zr(HPO 4) 2.

Synthesis and characterization of composite membranes based on α-zirconium phosphate and silicotungstic acid

The functional properties of the composite membrane generated from polyvinyl alcohol, zirconium phosphate and silicotungstic acid are described. The fabricated membranes were characterized by using FT-IR, XRD, TGA, DSC and SEM techniques. These fabricated membranes showed reduced methanol cross over (for possible application in DMFC) relative to that of Nafion ® 115. A maximum proton conductivity of 10 −2 S cm −1 at 60% RH was attained with 30 wt% STA incorporated composite membrane. This is however lower than that observed for Nafion ® 115 at 100% RH.

Preparation of α-zirconium phosphate nanoplatelets with wide variations in aspect ratios

Synthetic α-zirconium phosphate (α-ZrP) layer structures have been prepared via three different approaches. By controlling the concentration of reactants, temperature, pressure, and using a complexing agent, α-ZrP with a wide variation in aspect ratios has been prepared. Synthetic α-ZrP can be easily intercalated by amines and then exfoliated in epoxy to prepare polymer nanocomposites. Nanocomposites that contain exfoliated α-ZrP nanoplatelets with wide variations in aspect ratios can be utilized as model systems to study the structure–property relationship in polymer nanocomposites.

Improved quasi-solid dye-sensitized solar cells by composite ionic liquid electrolyte including layered α-zirconium phosphate

The authors reported a composite quasi-solid electrolyte by adding layered α-zirconium phosphate (α-ZrP) to the iodide/tri-iodide ionic liquid, 1-methyl-3-propylimidazolium dihydrophosphate, electrolyte including 4-tert-butylpyridine, which markedly improved photovoltaic properties of quasisolid dye-sensitized solar cells (DSSCs). When adding 6wt% α-ZrP, photoenergy conversion efficiency of the DSSC increases by a factor of more than 2 to 2.61%, compared to a DSSC without α-ZrP. This enhancement is primarily explained by studying dark reaction, diffusion coefficient of tri-iodide ions, exchange current density in the interface of electrolyte/Pt counterelectrode, and lifetime of electrons in mesoscopic TiO2 film.

Morphology and mechanical behavior of exfoliated epoxy/α-zirconium phosphate nanocomposites

The morphology and mechanical properties of synthetic α-zirconium phosphate (α-ZrP) based epoxy nanocomposites with 1 and 2 vol% of α-ZrP loadings were investigated. The state of exfoliation and dispersion were confirmed by X-ray diffraction and direct transmission electron microscopy imaging at various locations in the samples. Significant improvements in tensile modulus and tensile strength were observed. In this study, it is found that the fracture toughness values of the exfoliated epoxy nanocomposite systems are comparable to that of the neat epoxy. Detailed fracture mechanisms investigation indicates that no sign of crack deflection or nanoplatelet debonding is observed. Only a straight crack path is present. The nanoplatelets are broken into two halves as the crack propagates through them, indicating an existence of strong bonding between the nanoplatelet and epoxy matrix.

Enhanced exchange current density and diffusion coefficient of iodide-based liquid electrolyte by layered α-zirconium phosphate

Here, we firstly reported a composite electrolyte prepared by adding α-zirconium phosphate into the iodide/triiodide liquid electrolyte including 4- tert-butylpyridine (TBP). The obtained composite electrolyte exhibited very good electrochemical property. The exchange current density ( I 0) and the diffusion coefficient of triiodide ( D I 3 - ) were both enhanced markedly. It was proved that the intercalation behavior of TBP into layered α-ZrP could be responsible for their enhancement. The mechanism for the enhancement of I 0 and D I 3 - were investigated in detail, supported by X-ray diffraction (XRD) electrochemical impedance spectra (EIS) and limiting current measurements.

Intercalation and Exfoliation: A Review on Morphology of Polymer Nanocomposites Reinforced by Inorganic Layer Structures

ABSTRACT This review aims to address the morphology issues of polymer nanocomposites based on inorganic layer structures. Depending upon the degree of dispersion of nano-sized layer structure, polymer composites can be divided into three main categories: microcomposites, intercalated nanocomposites, and exfoliated nanocomposites. The exfoliated nanocomposites can be subdivided into ordered and disordered exfoliations. An intermediate morphology between intercalation and exfoliation, known as partial exfoliation, is also commonly seen. The above differences in morphology lead to significant variations in physical and mechanical properties of polymer nanocomposites. This review uses epoxy/clay nanocomposites to illustrate the development and recent achievements in the syntheses and exfoliation of polymer nanocomposites. Herein, a recent study on an epoxy nanocomposite based on synthetic α-zirconium phosphate is reviewed. The potential impact of using the synthetic α -zirconium phosphate as a reinforcement phase to develop fundamental understanding of the physical and mechanical behavior of polymer nanocomposites is discussed.

Protein/DNA/Inorganic Materials: DNA Binding to Layered α‐Zirconium Phosphate Enhances Bound Protein Structure and Activity

Successful intercalation of calf thymus DNA into the galleries of layered alpha zirconium phosphate (α-Zr(HPO4)2· H2O, α-ZrP) was facilitated by met-hemoglobin (Hb) and tetrabutylammonium (TBA) hydroxide. Intercalation of DNA, in turn, improved the properties of the co-intercalated protein. The protein structure, for example, was improved significantly and activities were enhanced by more than fivefold.

Spectroscopic studies of tris(2,2′-bipyridine)ruthenium(II) intercalated to modified α-zirconium phosphate

This paper presented the absorption and fluorescence spectra as well as luminescence lifetime of tris(2,2′-bipyridine)ruthenium(II) (abbreviated as Ru(bpy) 3 2+) intercalated to modified α-zirconium phosphate in aqueous media. The results showed extensive red shifts of the absorption band of the metal complex (from 454 to 482 nm) and blue shifts of the emission maximum (from 610 to 582 nm) as compared to that of free chromophore. On the other hand, the luminescence intensities and the excited-state lifetimes of the metal complex were dramatically increased. X-ray diffraction (XRD) patterns of the powder samples indicated that intercalation of Ru(bpy) 3 2+ into modified α-zirconium phosphate reduced somewhat the interlayer separation from 18.6 to 17.1 Å. In addition, spectroscopic measurements for Ru(bpy) 3 2+ with modified α-zirconium phosphate in ethanol media were also proceeded. No significant difference was observed, which implied that Ru(bpy) 3 2+ could not enter into modified α-zirconium phosphate in ethanol media.

Tuning the Properties of Hb Intercalated in the Galleries of α-ZrP with Ionic Strength: Improved Structure Retention and Enhanced Activity

The influence of ionic strength on the behavior of met-hemoglobin (Hb) bound to layered α-zirconium phosphate (α-ZrP) was investigated. Small increases in the ionic strength (5 mM to 80 mM K2HPO4, pH 7.2) indicated large improvements in the bound protein structure, activity, and stability. The number of ZrP units occupied per bound Hb (stoichiometry) increased from 773 to 2000 units. The Soret absorption band and the corresponding circular dichroism (CD) spectra (Soret) indicated that there are considerable improvements in the protein structure around the heme pocket with increase in ionic strength. Monitoring the UV−CD in the 190−250 nm range indicated only minor changes with ionic strength, and some formation of α-helical coiled coils was indicated. The peroxidase-like activity of the bound Hb increased approximately threefold when the ionic strength was increased from 10 mM to 40 mM K2HPO4 (pH 7.2). Free Hb did not indicate similar improvements in structure or activity. Differential scanning calorimetr...

Intercalation of polyetheramines into α-zirconium phosphate

Intercalation phenomena are important to many fields of science including chemistry because of the possibility of combining properties of two materials in a host–guest composite. The intercalation of α-zirconium phosphate with Jeffamines of different molecular weight is investigated. The interlayer spacing depends on the Jeffamine's chain length. The compounds are characterized by X-ray diffraction, infra-red spectroscopy and NMR. Interlayer spacings as large as 88 A were recorded. Similar intercalates were utilized to prepare an epoxy resin–zirconium phosphate nanocomposite.

Intercalation Mechanism and Interlayer Structure of Hexadecylamines in the Confined Space of Layered α-Zirconium Phosphates

Well-defined hexadecylamine (HDA) intercalated structures, either interdigitated layers, bilayers, or hybrid layers of both, in a confined space of highly functionalized layered alpha-zirconium phosphates (alpha-ZrPs) have been prepared based on the two-step intercalation mechanism and these distinct intercalated structures can serve as a model system to investigate the interactions of two monolayers whose amphiphilic tails are adjacent to each other. At the first intercalation step, the electrostatic interaction between HDAs and alpha-ZrP is dominant and results in an interdigitated layer structure (d(001) = 3.0 nm) and the interdigitated layer is saturated at around phi = 50%, where phi is the weight fraction of intercalated HDAs in the intergallery of alpha-ZrP. For phi higher than 50%, the bilayer structure (d(001) = 4.3 nm) emerges due to further hydrophobic interaction between HDAs initially grafted to alpha-ZrP and unanchored HDAs and the relative fraction of the bilayer structure over the interdigitated layer increases with the increase in the intercalated amount of HDAs. The intriguing morphology of alpha-ZrP tactoids intercalated with HDAs in coexisting bilayers and interdigitated layers is observed by using microtomed TEM and the two-step intercalation has also been verified with TGA and FT-IR. Also, a structural transition from the bilayers to the interdigitated layers is monitored by using in situ synchrotron WAXS showing that the hydrophobically intercalated HDAs are selectively deintercalated at a relatively low decomposition temperature around 220 degrees C.

Lead recovery from PbZrO 3 using wet ball-mill technique and hydrothermal synthesis of α-zirconium phosphate from wastewater for resource recovery

Lead recovery from lead zirconate (PbZrO 3) ceramics was investigated using a wet ball-mill treatment in H 2SO 4 aqueous solution. Subsequently crystalline α-zirconium phosphate (α-Zr(HPO 4) 2·H 2O) was synthesized using a hydrothermal technique in order for the resource recovery of zirconium in the wastewater after the wet ball-mill treatment. A wet ball-mill treatment in 4.5 M H 2SO 4 aqueous solution for 24 h was capable of converting more than 99.9% of the Pb initially included in the PbZrO 3 to solid state PbSO 4 with a purity of 98%. On the other hand, the Zr in the PbZrO 3 was dissolved into the acidic solution during the treatment. The Pb and Zr metal elements coexisting in PbZrO 3 were successfully separated by the wet ball-mill technique. Then, resource recovery of zirconium in the wastewater was examined. Crystalline α-Zr(HPO 4) 2·H 2O was synthesized by hydrothermal treatments in 3.1–12.5 M H 3PO 4 aqueous solutions at temperatures of 120–240 °C for a duration of 70 h. The hydrothermally prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and then they were also evaluated in terms of cation exchange capacity (CEC) measurement and thermogravimetric (TG) analysis.

Protein annealing: Thermal treatment of met-hemoglobin bound to α-zirconium phosphate/phosphonates results in initial denaturation followed by recovery of activity and structure

Thermal stability of met-hemoglobin (Hb) intercalated in three layered solid materials was investigated at 60 °C. At this temperature, free Hb undergoes rapid thermal denaturation, which is accompanied by the loss of its peroxidase-like activity and protein secondary structure. Heating of Hb intercalated in the galleries of α-zirconium(IV) phosphate (at 60 °C) also indicated initial loss of peroxidase-like activity of bound Hb, within 2 h. Continued equilibration of Hb bound to this solid (at 60 °C) indicated steady increase in its activity (>50%), as a function of continued equilibration at this temperature. The extent of this recovery also depended on the type surface functions present on the solid, and these are in the order α-Zr(PO 3CH 2CH 2COOH) 2 > α-Zr(PO 3CH 2COOH) 2 > α-Zr(HPO 4) 2. In the case of α-Zr(PO 3CH 2CH 2COOH) 2, the recovered activity was nearly twice as much as the activity, before heating. The circular dichroism spectra of the samples, heated at 60 °C for various time intervals, also indicated the initial loss of structure followed by significant recovery. This behavior is highly unusual, and these are the very first examples of activity recovery of proteins bound to solids, upon thermal treatment at moderate temperatures. These studies clearly indicate the important role of layered solids and their surface functions in the recovery of Hb structure. Annealing could be a useful method in recovering or improving the activities of specific proteins bound to selected solid surfaces.

Effect of Crystallinity on the Intercalation of Monoamine in α-Zirconium Phosphate Layer Structure

When the α-zirconium phosphate is of low crystallinity, guests are easy to intercalate into the entire gallery space, even at low intercalation ratio, and achieve a large interlayer distance. With increasing crystallinity, the intercalation turns out to be more difficult. A high degree of intercalation can only be achieved at a high intercalation ratio.