| 31. |
- Karlsson, Johan, et al.
(author)
-
The effect of alendronate on biomineralization at the bone/implant interface.
- 2016
-
In: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 104:3, s. 620-629
-
Journal article (peer-reviewed)abstract
- A recent approach to improve the osseointegration of implants is to utilize local drug administration. The presence of an osteoporosis drug may influence both bone quantity and quality at the bone/implant interface. Despite this, the performance of bone-anchoring implants is traditionally evaluated only by quantitative measurements. In the present study, the osteoporosis drug alendronate (ALN) was administrated from mesoporous titania thin films that were coated onto titanium implants. The effect that the drug had on biomineralization was explored both in vitro using simulated body fluid (SBF) and in vivo in a rat tibia model. The SBF study showed that the apatite formation was completely hindered at a high concentration of ALN (0.1 mg/mL). However, when ALN was administrated from the mesoporous coating the surface became completely covered with apatite. Ex vivo characterization of the bone/implant interface using Raman spectroscopy demonstrated that the presence of ALN enhanced the bone mineralization, and that the chemical signature of newly formed bone in the presence of ALN had a higher resemblance to the pre-existing mature bone than to the bone formed without drug. Taken together, this study demonstrates the importance of evaluating the quality of the formed bone to better understand the performance of implants. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A 104A: 620-629, 2016.
|
|
| 32. |
- Khan, Ziyauddin, et al.
(author)
-
Mass Transport in “Water-in-Polymer Salt” Electrolytes
- 2023
-
In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 35, s. 6382-6395
-
Journal article (peer-reviewed)abstract
- “Water-in-polymer salt” electrolytes (WiPSEs) based on potassium polyacrylate (PAAK) belong to a new family of “water-in-salt” electrolytes that is envisioned as a potential solution for large-scale supercapacitors to balance the electric grid at short time scales. The WiPSEs display a broad electrochemical stability window up to 3 V, yet they are nonflammable and provide high ionic conductivity (100 mS/cm) as required in high-power devices. However, the transport of matter in PAAK-based WiPSEs has not been studied. In this work, we have extensively characterized PAAK by spectroscopic methods such as Raman spectroscopy and NMR diffusometry to determine the state of water and elucidate the mechanism of ionic transport as well as its interplay with water and polymer chain dynamics, which reveals that a significant proportion of the transport in WiPSEs is attributed to hydrated cations. The results are further supported by molecular dynamics (MD) simulations. Finally, the potential of WiPSEs based on PAAK is demonstrated in an activated carbon-based supercapacitor operating up to 2 V with reasonable self-discharge. This proof of concept shows promise for low-cost and large-scale supercapacitors.
|
|
| 33. |
- Kumar, Divyaratan, et al.
(author)
-
Water-in-Polymer Salt Electrolyte for Long-Life Rechargeable Aqueous Zinc-Lignin Battery
- 2024
-
In: Energy & Environmental Materials. - : John Wiley & Sons. - 2575-0356 .- 2575-0348.
-
Journal article (peer-reviewed)abstract
- Zinc metal batteries (ZnBs) are poised as the next-generation energy storage solution, complementing lithium-ion batteries, thanks to their cost-effectiveness and safety advantages. These benefits originate from the abundance of zinc and its compatibility with non-flammable aqueous electrolytes. However, the inherent instability of zinc in aqueous environments, manifested through hydrogen evolution reactions (HER) and dendritic growth, has hindered commercialization due to poor cycling stability. Enter potassium polyacrylate (PAAK)-based water-in-polymer salt electrolyte (WiPSE), a novel variant of water-in-salt electrolytes (WiSE), designed to mitigate side reactions associated with water redox processes, thereby enhancing the cyclic stability of ZnBs. In this study, WiPSE was employed in ZnBs featuring lignin and carbon composites as cathode materials. Our research highlights the crucial function of acrylate groups from WiPSE in stabilizing the ionic flux on the surface of the Zn electrode. This stabilization promotes the parallel deposition of Zn along the (002) plane, resulting in a significant reduction in dendritic growth. Notably, our sustainable Zn-lignin battery showcases remarkable cyclic stability, retaining 80% of its initial capacity after 8000 cycles at a high current rate (1 A g-1) and maintaining over 75% capacity retention up to 2000 cycles at a low current rate (0.2 A g-1). This study showcases the practical application of WiPSE for the development of low-cost, dendrite-free, and scalable ZnBs. A dendrite-free and long-life cycle Zn-lignin battery was demonstrated using water-in-polymer salt electrolyte.
|
|
| 34. |
- Liu, Jian, 1985, et al.
(author)
-
Electrically Programmed Doping Gradients Optimize the Thermoelectric Power Factor of a Conjugated Polymer
- 2024
-
In: Advanced Functional Materials. - 1616-3028 .- 1616-301X. ; 34:18
-
Journal article (peer-reviewed)abstract
- Functionally graded materials (FGMs) are widely explored in the context of inorganic thermoelectrics, but not yet in organic thermoelectrics. Here, the impact of doping gradients on the thermoelectric properties of a chemically doped conjugated polymer is studied. The in-plane drift of counterions in moderate electric fields is used to create lateral doping gradients in films composed of a polythiophene with oligoether side chains, doped with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4TCNQ). Raman microscopy reveals that a bias voltage of as little as 5 V across a 50 µm wide channel is sufficient to trigger counterion drift, resulting in doping gradients. The effective electrical conductivity of the graded channel decreases with bias voltage, while an overall increase in Seebeck coefficient is observed, yielding an up to eight-fold enhancement in power factor. Kinetic Monte Carlo simulations of graded films explain the increase in power factor in terms of a roll-off of the Seebeck coefficient at high electrical conductivities in combination with a mobility decay due to increased Coulomb scattering at high dopant concentrations. Therefore, the FGM concept is found to be a way to improve the thermoelectric performance of not yet optimally doped organic semiconductors, which may ease the screening of new materials as well as the fabrication of devices.
|
|
| 35. |
- Martinelli, Anna, 1978, et al.
(author)
-
A H2/O2 Fuel Cell for In situ μ-Raman Measurements. In-depth Characterization of an Ionic Liquid Filled Nafion Membrane
- 2012
-
In: Fuel Cells. - : Wiley. - 1615-6846 .- 1615-6854. ; 12:2, s. 169-178
-
Journal article (peer-reviewed)abstract
- We report the design of a H2/O2 (fuel) cell for in situ μ-Raman spectroscopic measurements. The horizontal orientation of the cell is conceived to allow the penetration of the laser beam along the z-axis from one electrode to the other. We show that during in-depth analyses the Raman signal is not significantly lost and the axial resolution is sufficiently good to allow quantitative and qualitative spectral interpretation. We report “proof of principle” tests performed on Nafion membranes swelled with protic ionic liquids to demonstrate the validity of the design and the potentiality of the method. Our results confirm that this experimental setup can efficiently be used to follow structural changes and concentration gradients in the electrolyte of a fuel cell operando. In particular, we have been able to resolve both in time and in space the hydration state of the membrane as well as spatial variations for the coordination shell during a compositional transient state.
|
|
| 36. |
- Martinelli, Anna, 1978, et al.
(author)
-
A New Solid-State Proton Conductor: The Salt Hydrate Based on Imidazolium and 12-Tungstophosphate
- 2021
-
In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 143:34, s. 13895-13907
-
Journal article (peer-reviewed)abstract
- We report the structure and charge transport properties of a novel solid-state proton conductor obtained by acid-base chemistry via proton transfer from 12-tungstophosphoric acid to imidazole. The resulting material (henceforth named Imid3WP) is a solid salt hydrate that, at room temperature, includes four water molecules per structural unit. To our knowledge, this is the first attempt to tune the properties of a heteropolyacid-based solid-state proton conductor by means of a mixture of water and imidazole, interpolating between water-based and ionic liquid-based proton conductors of high thermal and electrochemical stability. The proton conductivity of Imid3WP·4H2O measured at truly anhydrous conditions reads 0.8 × 10-6 S cm-1 at 322 K, which is higher than the conductivity reported for any other related salt hydrate, despite the lower hydration. In the pseudoanhydrous state, that is, for Imid3WP·2H2O, the proton conductivity is still remarkable and, judging from the low activation energy (Ea = 0.26 eV), attributed to structural diffusion of protons. From complementary X-ray diffraction data, vibrational spectroscopy, and solid-state NMR experiments, the local structure of this salt hydrate was resolved, with imidazolium cations preferably orienting flat on the surface of the tungstophosphate anions, thus achieving a densely packed solid material, and water molecules of hydration that establish extremely strong hydrogen bonds. Computational results confirm these structural details and also evidence that the path of lowest energy for the proton transfer involves primarily imidazole and water molecules, while the proximate Keggin anion contributes with reducing the energy barrier for this particular pathway.
|
|
| 37. |
- Martinelli, Anna, 1978, et al.
(author)
-
A structural study on ionic-liquid-based polymer electrolyte membranes
- 2007
-
In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 154:8, s. G183-G187
-
Journal article (peer-reviewed)abstract
- We have investigated novel proton conducting membranes synthesized through the gelification of poly(vinylidene fluoride-co-hexafluoropropylene) in aprotic ionic liquids. Mobile protons were introduced by doping the system with the strong bis(trifluoromethanesulfonyl)imide acid (HTFSI), which is chemically compatible with the ionic liquids through the common TFSI- anion. The obtained membranes are thermally stable up to 115°C set by the melting of the polymer phase. At this temperature, the conductivity is on the order of 10-2 S cm-1. Raman and infrared spectroscopy show no chemical interactions between the components, indicating that the bulklike nature of the doped ionic liquids preserved within the membrane, as is the thermal stability and the high conductivity. © 2007 The Electrochemical Society.
|
|
| 38. |
- Martinelli, Anna, 1978, et al.
(author)
-
A study on the state of PWA in PVDF-based proton conducting membranes by Raman spectroscopy
- 2007
-
In: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 178:7-10, s. 527-531
-
Journal article (peer-reviewed)abstract
- Polymer composite proton conducting membranes with increasing amount of tungstophosphoric acid (PWA) have been synthesized starting from poly(vinylidene) fluoride and alumina. Membranes could be prepared with an acid loading up to 16.7 wt.%. The conductivity of the membranes increases with acid loading up to 10- 3 Scm- 1 at the highest loading. The membrane matrices have a good thermal stability up to 240 °C, however a loss of water absorbed during the preparation procedure is observed at a considerably lower temperature. Raman spectroscopy showed that in the membrane the polymer adopts a conformation that could promote a separation into hydrophilic/hydrophobic sites. An interaction between alumina and PWA is also found that might limit the conductivity of the membranes.
|
|
| 39. |
|
|
| 40. |
- Martinelli, Anna, 1978, et al.
(author)
-
An investigation of the sol-gel process in ionic liquid/silica gels by time resolved Raman and 1H NMR spectroscopy
- 2012
-
In: Physical Chemistry Chemical Physics. - 1463-9084 .- 1463-9076. ; 14:38, s. 13216-13223
-
Journal article (peer-reviewed)abstract
- We report, by employing time resolved Raman and nuclear magnetic resonance (NMR) spectroscopy, on the gelation process in ionogels. These are prepared from a non-aqueous sol–gel reaction in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C1C6ImTFSI). Raman and NMR spectroscopies are complementarily used to decipher the chemical reactions that occur during synthesis and to clarify the state of the ionic liquid up to, and well beyond, gelation. We find that the ionic liquid concentration affects both the reaction rate and the gelation time (tgel). In addition, NMR and Raman data reveal inherently different roles of the cation and the anion in the gelation process. While the oscillating behavior of the TFSI Raman signature at 740 cm−1 is mainly an effect of solvation and chemical composition, the evolution of the relative chemical shifts (Δδ) of different hydrogen atoms on the imidazolium correlates with gelation, as does the width of the chemical shift of –OH containing groups (δOH). We also observe that in the confined state the TFSI anion preferably adopts the cisoid conformation and experiences a stronger ion–ion interaction.
|
|
