Phosphonic Acid Groups Research Articles

Dynamic Temperature Control System for the Optimized Production of Liquid Metal Nanoparticles

Nanoparticles (NPs) of gallium-based liquid metal (LM) alloys have potential applications in flexible electronics, drug delivery, and molecular imaging. They can be readily produced using top-down methods such as sonication. However, the sonication process generates heat that can cause dealloying of NPs through hydrolysis and oxidation of gallium. This limits the sonication power and period that can be applied for disrupting LM into smaller particles with high concentrations. Also, it remains challenging to achieve long-term colloidal stability of NPs in biological buffers. Here, we develop a dynamic temperature control system for improving the production performance of LM NPs. The enhanced performance is reflected by the significantly increased particle concentration, the decreased overall particle size, the prevention of the formation of oxide nanorods, and the versatility of producing NPs of different types of alloys. In addition, we design a brushed polyethylene glycol polymer with multiple phosphonic acid groups for effectively anchoring the NPs. More importantly, we discover that phosphate can effectively passivate the surface of NPs to further improve their stability. Using these strategies, the produced NPs remain stable in biological buffers for at least six months. Thus, the proposed methods can unleash the vast potential of LM NPs for biomedical applications.

Polyanionic self-healing hydrogels for the controlled release of cisplatin

The development of multifunctional self-healing hydrogels is limited by the lack of simple methods to prepare multifunctional polymers. In this work, a multifunctional polymer containing phenylboronic acid (PBA) and phosphonic acid (PA) groups was prepared via a one-step Kabachnik-Fields (KF) reaction and free radical polymerization followed by an effective hydrolysis reaction. The negatively-charged polymer can react with poly(vinyl alcohol) to generate a polyanionic self-healing hydrogel under mild conditions (25 °C, pH = 7.4) via dynamic borate ester bonds. The hydrogel has a low cytotoxicity and can be used for 3D cell culture. The negative charged PA groups in this hydrogel efficiently bind positively-charged cisplatin, resulting in a significant improvement of its safety. The polyanionic self-healing hydrogel demonstrates a new application of the KF reaction in interdisciplinary areas that will prompt broader studies on multicomponent reactions in polymer chemistry and material science.

Organic-inorganic backbone with high contents of proton conducting groups: A newly designed high performance proton conductor

To prepare new high temperature organic-inorganic proton conductor for applications in proton exchange membrane fuel cells (PEMFC), 2,4,6-triphosphono-1,3,5-triazine (TPT) was synthesized and reacted with three different types of metal ions (Ce, Zr and Fe) in varied molar ratios. In each TPT molecule, three phosphonic acid groups were introduced into the triazine ring to obtain an organic compound with high content of proton conducting groups, which was then reacted with metal ions to ensure the insolubility in water aiming to avoid leaking during PEMFC operation. CeTPT(1:2) exhibited good thermal stability up to 200 °C and showed crystalline phase. MTPT exhibited high ion exchange capacity (IEC, 1.53–2.12 meq. g−1). CeTPT(1:2) exhibited highest proton conductivity among all samples, which reached 0.116, 0.070 and 0.034 S cm−1 at 100% relative humidity (RH), 50% RH and anhydrous conditions at 180 °C, respectively. The corresponding activation energy for proton conduction was 14.5, 16.0 and 21.5 kJ mol−1 at 100% RH, 50% RH and anhydrous conditions, respectively. The mechanism for proton conduction was proposed according to the activation energy. The proton conductor can find promising applications in fuel cells, corrosion inhibition and water desalination due to its good thermal stability and high IEC.

A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO-Based Dye-Sensitized Solar Cells.

The anchoring group of a sensitizer may strongly affect the overall properties and stability of the resulting dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthetic solar cells (DSPECs). The properties of seven perylene monoimide (PMI) dyes have been comprehensively studied for their immobilization on nanocrystalline NiO film. The PMI dyes differ only by the nature of the anchoring group, which are: carboxylic acid (PMI-CO2 H), phosphonic acid (PMI-PO3 H2 ), acetyl acetone (PMI-acac), pyridine (PMI-Py), aniline (PMI-NH2 ), hydroxyquinoline (PMI-HQ), and dipicolinic acid (PMI-DPA). The dyes are investigated by cyclic voltammetry and spectroelectrochemistry and modeled by TD-DFT quantum chemical calculations. The mode of binding of these anchoring groups is investigated by infrared spectroscopy and the stability of the binding to NiO surface is studied by desorption experiments in acidic and basic media. The phosphonic acid group is found to offer the strongest binding to the NiO surface in terms of stability and dye loading. Finally, a photophysical study by ultrafast transient absorption spectroscopy shows that all dyes inject a hole in NiO with rate constants on a subpicosecond timescale and display similar charge recombination kinetics. The photovoltaic properties of the dyes show that PMI-HQ and PMI-acac give the highest photovoltaic performances, owing to a lower degree of aggregation on the surface.

On-device lead sequestration for perovskite solar cells.

Perovskite solar cells, as an emerging high-efficiency and low-cost photovoltaic technology1-6, face obstacles on their way towards commercialization. Substantial improvements have been made to device stability7-10, but potential issues with lead toxicity and leaching from devices remain relatively unexplored11-16. The potential for lead leakage could be perceived as an environmental and public health risk when using perovskite solar cells in building-integrated photovoltaics17-23. Here we present a chemical approach for on-device sequestration of more than 96 per cent of lead leakage caused by severe device damage. A coating of lead-absorbing material is applied to the front and back sides of the device stack. On the glass side of the front transparent conducting electrode, we use a transparent lead-absorbing molecular film containing phosphonic acid groups that bind strongly to lead. On the back (metal) electrode side, we place a polymer film blended with lead-chelating agents between the metal electrode and a standard photovoltaic packing film. The lead-absorbing films on both sides swell to absorb the lead, rather than dissolve, when subjected to water soaking, thus retaining structural integrity for easy collection of lead afterdamage.

Local Structures and Dynamics of Imidazole Molecules in Poly(vinylphosphonic acid)–Imidazole Composite Investigated by Molecular Dynamics

The composite materials of acidic polymers and imidazole (Im) exhibit good high-proton conduction, making them potentially useful in proton-exchange membrane fuel cells. The proton conduction mechanism must be clearly elucidated for the design of future high proton-conduction materials. This study examines the local hydrogen-bonding structures and dynamics of Im for proton-conducting poly(vinylphosphonic acid)-Im (PVPA-xIm) composites by using molecular dynamics simulations. Radial distribution functions (RDFs) characterize the hydrogen bonds between Im or imidazolium cation (ImH+) and phosphonic acid (PA) group and among Im molecules. RDFs and diffusion coefficients suggest that the intercalation of Im to PVPA reduces Im mobility because of the interaction between Im and PA groups. However, similar to pure Im, the amount of Im with fast rotational motions increases as the amount of Im increases. Our study leads us to conclude that long-range proton transport occurs through the hydrogen-bonding network of...

Polymers of vinylphosphonic acid, acrylonitrile, and methyl acrylate and their nanofibers

AbstractIn this study, a small amount of vinylphosphonic acid was used to produce fire‐retardant copolymers and terpolymers from acrylonitrile and methyl acrylate. The structures of copolymer and terpolymers were elucidated by 1H‐NMR and phosphorous analysis. Thermal decomposition of vinylphosphonic acid‐containing copolymers and terpolymers started at lower temperatures than of poly(acrylonitrile‐co‐methyl acrylate). Methyl acrylate contributes to the thermal resistance of the terpolymers. Poly(acrylonitrile‐co‐methyl acrylate‐co‐vinylphosphonic acid) with a phosphorous content about 0.25% burned at a slower rate and emitted less smoke compared to poly(acrylonitrile‐co‐methyl acrylate). The burning tests showed that both copolymer and terpolymers containing vinylphosphonic acid behaved as a fire‐retardant polymer. The phosphonate and phosphonic acid groups in the copolymer and terpolymers accelerate the cyclization of nitrile groups and inhibit the fire in the gas phase. Nanofibers were successfully produced by the electrospinning method from the copolymers and terpolymers containing vinylphosphonic acid moiety.

Phosphonic Acid Coupling Agent Modification of HAP Nanoparticles: Interfacial Effects in PLLA/HAP Bone Scaffold.

In order to improve the interfacial bonding between hydroxyapatite (HAP) and poly-l-lactic acid (PLLA), 2-Carboxyethylphosphonic acid (CEPA), a phosphonic acid coupling agent, was introduced to modify HAP nanoparticles. After this. the PLLA scaffold containing CEPA-modified HAP (C-HAP) was fabricated by selective laser sintering (frittage). The specific mechanism of interfacial bonding was that the PO32− of CEPA formed an electrovalent bond with the Ca2+ of HAP on one hand, and on the other hand, the –COOH of CEPA formed an ester bond with the –OH of PLLA via an esterification reaction. The results showed that C-HAP was homogeneously dispersed in the PLLA matrix and that it exhibited interconnected morphology pulled out from the PLLA matrix due to the enhanced interfacial bonding. As a result, the tensile strength and modulus of the scaffold with 20% C-HAP increased by 1.40 and 2.79 times compared to that of the scaffold with HAP, respectively. In addition, the scaffold could attract Ca2+ in simulated body fluid (SBF) solution by the phosphonic acid group to induce apatite layer formation and also release Ca2+ and PO43− by degradation to facilitate cell attachment, growth and proliferation.

Ethyl phosphoric acid grafted amino-modified polybenzimidazole with improved long-term stability for high-temperature proton exchange membrane applications

A series of membranes based on amino-modified polybenzimidazole with grafted ethyl phosphonic acid have been successfully prepared. Firstly, the amino-modified polybenzimidazole (PBI-NH2-X) was synthesized, then the ethyl phosphoric acid (EPA) were grafted on to PBI-NH2-X to obtained amino-modified polybenzimidazoles with grafted ethyl phosphonic acid groups (PBI-NH2-EPA-X). EPA is introduced into the matrix to improve the H3PO4 doping level and proton conductivity of the membranes. The obtained membranes display good dimensional and thermal stability. Long-term stability of the grafted membranes is much better than the pristine PBI membranes. Moreover, PBI-NH2-EPA-15 shows a proton conductivity of 0.062 S cm−1 at 170 °C, which is 342% higher than that of PBI.

Insights on uranium uptake mechanisms by ion exchange resins with chelating functionalities: Chelation vs. anion exchange

Abstract X-ray absorption fine structure analysis has been successfully used to determine the coordination environment and therefore uptake mechanism towards the uranyl cation for a selection of commercially available ion exchange resins in non-saline and saline conditions ([Cl−] = 22.7 g L−1, 0.64 M) similar to those found in sea water. The resins tested were Purolite S985, S910 and S957, Dowex M4195, Ps-EDA, Ps-DETA and Ps-PEHA, which contain polyamine, amidoxime, mixed sulfonic/phosphonic acid, bispicolylamine, ethylenediamine, diethylenetriamine and pentaethylenehexamine functional groups, respectively. Purolite S910 and S957 were both found to extract the uranyl cation through a chelation mechanism. The uranium coordination environment on uranyl loaded Purolite S910 was found to be either tetra- or hexa-coordinate in the equatorial plane, with a 2:1 ratio of amidoxime:uranium in the fit suggesting either monodentate or η2 coordination by two amidoxime groups. The uranium environment for uranyl loaded Purolite S957 was found to be tetra-coordinate in the equatorial plane, with both sulfonic and phosphonic acid groups being involved in sorption. The presence of chloride in the loading solution had no effect on the uranyl coordination environment observed on any of the resins. In contrast, Dowex M4195, Purolite S985, Ps-EDA, Ps-DETA and Ps-PEHA exhibited an anion exchange mechanism for uranyl uptake as the corresponding extended X-ray absorption fine structure (EXAFS) data best fit a [UO2(SO4)3]4− structure.

Highly efficacious entrapment of Th (IV) and U (VI) from rare earth elements in concentrated nitric acid solution using a phosphonic acid functionalized porous organic polymer adsorbent

It is challenging to extract Th (IV) and U (VI) from rare earth elements (REEs) in concentrated acidic solution. Herein, a nanoporous polymer adsorbent P (DVB-VPA) bearing phosphonic acid groups has been synthesized by solvothermal copolymerization of divinylbenzene (DVB) and vinylphosphonic acid (VPA). The maximum adsorption capacity (qmax) for Th (IV) and U (VI) onto P (DVB-VPA) was estimated to be 354.6 and 216.5 mg g−1 at 298 K in 4 mol L−1 of hydrogen nitrate media, which were much larger than most of the adsorbents reported previously. Besides, P (DVB-VPA) exhibited a good selectivity for Th (IV) and U (VI) from REEs in concentrated nitric acid solution, since the values of the selectivity for Th (IV) and U (VI) over La (III), Ce (III), Eu (III), Nd (III) and Sm (III) were 82.2% and 72.5%, respectively. XPS analysis revealed that the adsorption mechanism was achieved through the complexation of PO ligands anchored onto the polymer skeleton of P (DVB-VPA) with thorium and uranium. Due to P (DVB-VPA) showed a larger binding force toward Th (IV) than U (VI), both q max and selectivity for Th (IV) in concentrated hydrogen nitrate media was larger than those for U (VI) on P (DVB-VPA), which has been confirmed by DFT calculations.

Novel proton exchange membranes based on sulfonated poly (ether-ether-ketone)/phosphonic acid-functionalized siloxane

Novel proton exchange membranes of sulfonated poly (ether-ether-ketone)/phosphonic acid-functionalized siloxane were prepared by sol–gel method using sulfonated poly (ether-ether-ketone) as the matrix and phosphonic acid-functionalized siloxane as the crosslinking agent. Phosphonic acid-functionalized siloxane was prepared from tetra sodium of 1-hydroxyethane-1, 1-diphosphonic acid (HEDP·Na4) and 3-isocyanatopropyltriethoxysilane (IPTES). The FTIR results suggest that HEDP·Na4 was anchored into IPTES and Si-O-Si crosslinked network was formed successfully. The prepared membranes were stable up to 220 °C without any degradation and exhibited excellent dimensional stability and mechanical performance. The proton conductivity of the AES-X increased with the increase of phosphonic acid groups, especially for AES-3, 4, of which the proton conductivity was higher than that of Nafion117 at 80 °C and the proton conductivity of AES-3 was up to 0.0378 S cm−1 under 140 °C. The power density of the DMFC MEA fabricated with the AES-3 could reach 157 mW cm−2 at 60 °C.

Studies on new highly phosphonated poly (ether ether ketone) based promising proton conducting membranes for high temperature fuel cell

The present study deals with the development of poly ether ether ketone (PEEK) based proton exchange membrane (PEM) having phosphonic acid as protogenic moiety. The synthesis of phosphonated PEEK was carried out in two simpler steps i.e. chloromethylation followed by phosphonation through Michaelis-Arbuzov reaction. The product was further investigated for structural property through FTIR, 1H NMR, 13C NMR, 31P NMR and XRD while thermal properties were analysed by TGA. Other physical properties such as ion exchange capacity, water uptake and proton conductivity were determined for the prepared membranes to execute their suitability as PEM. The presence of phosphonic acid group provides good thermal and chemical stability to the membranes. The high substitution degree (1.11–1.56) achieved in present case was favourable for providing significant proton conductivity of 0.047 S/cm at 120 °C under hydrated conditions to the corresponding membranes which entitle them as potential candidate for PEMs in fuel cells at high temperature.

Organometallic Iridium(III) Complex Sensitized Ternary Hybrid Photocatalyst for CO2 to CO Conversion.

A series of heteroleptic iridium(III) complexes functionalized with two phosphonic acid (-PO3 H2 ) groups (dfppy IrP, ppy IrP, btp IrP, and piq IrP) were prepared and anchored onto rhenium(I) catalyst (ReP)-loaded TiO2 particles (TiO2 /ReP) to build up a new IrP-sensitized TiO2 photocatalyst system (IrP/TiO2 /ReP). The photosensitizing behavior of the IrP series was examined within the IrP/TiO2 /ReP platform for the photocatalytic conversion of CO2 into CO. The four IrP-based ternary hybrids showed increased conversion activity and durability than that of the corresponding homo- (IrP+ReP) and heterogeneous (IrP+TiO2 /ReP) mixed systems. Among the four IrP/TiO2 /ReP photocatalysts, the low-energy-light (>500 nm) activated piq IrP immobilized ternary system (piq IrP/TiO2 /ReP) exhibited the most durable conversion activity, giving a turnover number of ≥730 for 170 h. A similar kinetic feature observed through time-resolved photoluminescence measurements of both btp IrP/TiO2 and TiO2 -free btp IrP films suggests that the net electron flow in the ternary hybrid proceeds dominantly through a reductive quenching mechanism, unlike the oxidative quenching route of typical dye/TiO2 -based photolysis.

Preparation and characterization of PVA proton exchange membranes containing phosphonic acid groups for direct methanol fuel cell applications

In this paper, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), which is an organic phosphonic acids (OPA), is selected as the protic media to prepare phosphonated proton exchange membranes based on polyvinyl alcohol (PVA) by solution casting technique. The obtained PVA membranes were characterized using fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and wide angle X-ray diffraction (WAXD). The proton conductivities and the methanol permeabilities through the membranes were investigated in terms of various OPA content. The proton conductivity of the PVA membrane measured at room temperature was close to that of the nafion-117 membrane measured under the same test conditions (1.02 × 10−3 S·cm−1). But in the low relative humidity (50%), the proton conductivity of the phosphonic proton exchange membrane has a conductivity of up to 8.17 × 10−5 S·cm−1, which was significantly higher than that of the sulfonate proton exchange membrane. The methanol permeabilities of the PVA membranes were in the range of 10−7 to 10−6 cm2/s in the room temperature, depending on the OPD content. The thermal stability of the composite membrane was enhanced with incorporating of PBTCA by presenting high initial decomposition temperature.

Synthesis of polyaminophosphonic acid-functionalized poly(glycidyl methacrylate) for the efficient sorption of La(III) and Y(III)

After synthesis of parent PGMA micro-particles by dispersion polymerization method, diethylenetriamine (DETA) is grafted on the polymer (DETA-PGMA). In the last step, methylene phosphonic groups are grafted on DETA-PGMA by reaction of phosphonic acid groups onto amine functions in the presence of formaldehyde to produce polyaminophosphonic acid sorbent (PPA-PGMA). The sorbent is characterized by elemental analysis, FTIR spectrometry, XPS, XRD, TG-TDA and SEM-EDX analyses. The sorption properties of the material are tested for the sorption of La(III) and Y(III): the effect of pH on sorption performance is investigated before studying uptake kinetics, sorption isotherms (and thermodynamics), metal desorption and sorbent recycling. Maximum sorption capacities reach up to 0.79 mmol La g−1 and 0.73 mmol Y g−1 at pH 5 (optimum initial pH value). Sorption isotherms are characterized by a saturation plateau: the Langmuir equation fits well data. The sorption on micron-sized particles is fast and equilibrium is reached within 3–4 h: the kinetic profiles are modelled by the Crank equation (resistance to intraparticle diffusion) though the pseudo-first order rate equation fits well experimental data. Nitric acid (0.5 M) solutions can be used for metal recovery and the sorbent is re-used for at least 6 cycles of sorption and desorption with limited decrease in performance (less than 7%). The sorbent has a preference at pH 5 for La(III) vs. Y(III) but the selectivity coefficient is not high enough for potentiating the selective separation of the two metals.

Extremely high extraction ability of bisphosphonic acid type extraction reagent for a series of rare earth metal ions

A bisphosphonic acid type extraction reagent has been synthesised and employed to investigate the extraction behaviour towards rare-earth metals. The new reagent exhibited extremely high extraction ability for these ions. This ability was also accompanied by low leakage of extractant into the aqueous phase reflecting the reagent’s hydrophobic nature and the presence of partially undissociated phosphonic acid groups.

Adsorption of Phosphonic-Acid-Functionalized Porphyrin Molecules on TiO2(110)

We studied the adsorption geometry and bonding of mono- and tetraphosphonic-acid-functionalized tetraphenylporphyrin molecules on rutile TiO2(110) surfaces. The investigation was carried out by means of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure (NEXAFS) measurements. We found that the molecules bind covalently to the surface in a mixed monodentate and bidentate mode implying deprotonation of one or two phosphonate hydroxyl groups. Our NEXAFS data suggest that molecules containing one functional phosphonic acid group are on average tilted further away from the surface than molecules with four functional groups. The highest occupied electronic state of both molecules is in the band gap at 2.1 eV below the Fermi level. Our results demonstrate that the number of functional phosphonic acid groups determine the adsorption geometry of tetraphenylporphyrins.

Preparation of polymer electrolyte membranes based on poly(phenylene oxide) with different side chain lengths of phosphonic acid

ABSTRACTA series of poly(phenylene oxide) (PPO) polymers bearing phosphonic acid groups on the methyl group and on the phenyl ring are synthesized as membrane materials for fuel cell applications. These phosphonic acid‐based PPO membranes exhibited high chemical resistance, dimensional stability, and good proton conductivity even under low humidity condition. Among the membranes, the one in which the phosphonic acid moiety is attached to the polymer main chain with CO(CH2)5 shows highest proton conductivity under overall conditions even though it has the lowest water uptake and IEC value. A well‐defined separation of the hydrophilic and hydrophobic phases suggests the phosphonic acid groups to form proton conduction channels via interchain hydrogen bonding. A high storage modulus of the membranes in various temperature ranges indicates that the membranes are suitable for use under a high temperature and low humidity conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019

Ab initio Study of Anchoring Groups for CuGaO2 Delafossite-Based p-Type Dye Sensitized Solar Cells.

Here we report the first theoretical characterization of the interface between the CuGaO2 delafossite oxide and the carboxylic (–COOH) and phosphonic acid (–PO3H2) anchoring groups. The promising use of delafossites as effective alternative to nickel oxide in p-type DSSC is still limited by practical difficulties in sensitizing the delafossite surface. Thus, this work provides atomistic insights on the structure and energetics of all the possible interactions between the anchoring functional groups and the CuGaO2 surface species, including the effects of the Mg doping and of the solvent medium. Our results highlight the presence of a strong selectivity toward the monodentate binding mode on surface Ga atoms for both the carboxylic and phosphonic acid groups. Since the binding modes have a strong influence on the hole injection thermodynamics, these findings have direct implications for further development of delafossite based p-type DSSCs.