scholarly journals Effects of Cooling Rates on Self-Assembling Structures of 12-Hydroxystearic Acid in an Ionic Liquid

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hiroyuki Takeno ◽  
Mai Kozuka
Keyword(s):  
Ionic Liquid ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Solution Temperature ◽  
Hydroxystearic Acid ◽  
Cooling Process ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Self Assembling ◽  
Polymorphic Forms

We investigated effects of cooling rates on self-assembling structures and mechanical and electrochemical properties of 12-hydroxystearic acid (12-HSA) in an ionic liquid (IL), 1-allyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide ([ABIm][TFSI]). The mixture of 12-HSA with [ABIm][TFSI] had an upper critical solution temperature (UCST) above the sol-gel transition temperature, and the microstructure of the ionogel was significantly affected by cooling rates, where it was prepared. The twisted self-assembling structure was formed during a slow cooling process at a rate of 0.4°C/min, whereas spherical domains caused by the liquid-liquid phase separation and radiate fibrous structure were observed for the quenched gel. The real-time small-angle X-ray scattering (SAXS) measurements for the ionogel during a slow cooling process at a rate of 0.4°C/min presented three different (001) peaks arising from long spacings of 46.5, 42.4, and 39.7 Å, which were also observed for SAXS curves of a neat 12-HSA. These results suggest that three polymorphic forms of 12-HSA are formed in the IL. The polymorphic form significantly affected the mechanical properties of the ionogel, whereas it did not affect the ionic conductivity. The ionic conductivity of the ionogel was close to that of a neat [ABIm][TFSI] irrespective of the polymorphic forms of 12-HSA.

scholarly journals Comparison of the Ionic Conductivity Properties of Microporous and Mesoporous MOFs Infiltrated with a Na-Ion Containing IL Mixture

2020 ◽  
Author(s):  
Joshua Tuffnell ◽  
Jędrzej K. Morzy ◽  
Rui Tan ◽  
Qilei Song ◽  
Caterina Ducati ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Ionic Conductivities ◽  
Zeolitic Imidazolate Framework ◽  
Hierarchically Porous ◽  
Framework Materials ◽  
Sol Gel Synthesis

IL@MOF (IL: ionic liquid; MOF: metal-organic framework) materials have been proposed as a candidate for solid-state electrolytes, combining the inherent non-flammability and high thermal and chemical stability of the ionic liquid with the host-guest interactions of the MOF. In this work, we compare the structure and ionic conductivity of a sodium ion containing IL@MOF composite formed from a microcrystalline powder of the zeolitic imidazolate framework (ZIF), ZIF-8 with a hierarchically porous sample of ZIF-8 containing both micro- and mesopores from a sol-gel synthesis. Although the crystallographic structures were shown to be the same by X-ray diffraction, significant differences in particle size, packing and morphology were identified by electron microscopy techniques which highlight the origins of the hierarchical porosity. After incorporation of Na0.1EMIM0.9TFSI (abbreviated to NaIL; EMIM = 1-ethyl-3-methylimidazolium; TFSI = bis(trifluoromethylsulfonyl)imide), the hierarchically porous composite exhibited a 40 % greater filling capacity than the purely microporous sample which was confirmed by elemental analysis and digestive proton NMR. Finally, the ionic conductivity properties of the composite materials were probed by electrochemical impedance spectroscopy. The results showed that despite the 40 % increased loading of NaIL in the NaIL@ZIF-8micro sample, the ionic conductivities at 25 °C were 8.4x10-6 and 1.6x10-5 S cm-1 for NaIL@ZIF-8meso and NaIL@ZIF-8micro respectively. These results exemplify the importance of the long range, continuous ion pathways contributed by the microcrystalline pores, as well as the detrimental effect of discontinuous and tortuous mesoporous pathways which show a limited contribution to the overall ionic conductivity. <br>

Iron-Silicate Glassy Films by Sol-Gel Conversion Induced by Rapid Thermal Processing

1998 ◽  
Vol 525 ◽  
Author(s):  
René E. Van De Leest ◽  
Fred Roozeboom
Keyword(s):  
Cooling Rate ◽  
Thermal Processing ◽  
Sol Gel ◽  
Rapid Thermal Processing ◽  
Iron Silicate ◽  
Precursor Film ◽  
Vibration Band ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Oh Groups

ABSTRACTThe sol-gel system iron triethoxide - tetraethylorthosilicate (TEOS) with the Fe/Si atomic ratio ranging from 0 to 1 has been investigated. Our study leads to the conclusion that the annealing method of the hydrolyzed precursor film determines the type of solid film formed. Annealing by Rapid Thermal Processing (RTP) with its high heating and cooling rates yields amorphous, glassy iron silicate films. These films result from polycondensation reactions between Si-OH and Fe-OH groups of the hydrolyzed precursors forming Fe-O-Si and Si-O-Si bonds. These bonds show a characteristic vibration band in FTIR spectra, which is most intense for Fe/Si = 1, and shifts for increasing Fe/Si ratio from 1073 down to 965 cm-1.The iron silicate film with Fe/Si =1 obtained by RTP displays an optical absorption band around 320 nm, which indicates that Fe3+-ions have a tetrahedral coordination similar to the Si4+-ions in Si02 and glass with tetrahedrally coordinated silicon and iron ions linked by bridging oxygen atoms. The films, typically 0.1 μm thick, annealed by RTP have a smooth, mechanically hard surface. This glassy structure can be formally presented as FeSiOx. Conventional furnace heating with low heating/cooling rates yields nanocrystalline films with predominantly Si-O-Si bonding in grains with sizes below 40 nm. More structural and chemical investigation is needed to elucidate the details of the structure and the formation mechanism of the amorphous compound, but we can conclude that the cooling rate has a direct effect on the degree of non-crystallinity of the compound. The high cooling rate of RTP will retain the Fe-O-Si bonds formed in a state of inequilibrium, and “quench” them in an amorphous, metastable glass compound, whereas slow cooling gives rise to nanocomposite film formation.

scholarly journals Alginate-g-PNIPAM-Based Thermo/Shear-Responsive Injectable Hydrogels: Tailoring the Rheological Properties by Adjusting the LCST of the Grafting Chains

2021 ◽  
Vol 22 (8) ◽  
pp. 3824
Author(s):  
Konstantinos Safakas ◽  
Sofia-Falia Saravanou ◽  
Zacharoula Iatridi ◽  
Constantinos Tsitsilianis
Keyword(s):  
Body Temperature ◽  
Rheological Properties ◽  
Sol Gel ◽  
Aqueous Media ◽  
Random Copolymer ◽  
Solution Temperature ◽  
Self Assembling ◽  
Potential Applications ◽  
Weak Gel ◽  
Phosphate Buffered Saline

Graft copolymers of alginate backbone and N-isopropylacrylamide/N-tert-butylacrylamide random copolymer, P(NIPAMx-co-NtBAMy), side chains (stickers) with various NtBAM content were designed and explored in aqueous media. Self-assembling thermoresponsive hydrogels are formed upon heating, in all cases, through the hydrophobic association of the P(NIPAMx-co-NtBAMy) sticky pendant chains. The rheological properties of the formulations depend remarkably on the NtBAM hydrophobic content, which regulates the lower critical solution temperature (LCST) and, in turn, the stickers’ thermo-responsiveness. The gelation point, Tgel, was shifted to lower temperatures from 38 to 20 °C by enriching the PNIPAM chains with 20 mol % NtBAM, shifting accordingly to the gelation temperature window. The consequences of the Tgel shift to the hydrogels’ rheological properties are significant at room and body temperature. For instance, at 37 °C, the storage modulus increases about two orders of magnitude and the terminal relaxation time increase about 10 orders of magnitude by enriching the stickers with 20 mol % hydrophobic moieties. Two main thermo-induced behaviors were revealed, characterized by a sol–gel and a weak gel–stiff gel transition for the copolymer with stickers of low (0.6 mol %) and high (14, 20 mol %) NtBAM content, respectively. The first type of hydrogels is easily injectable, while for the second one, the injectability is provided by shear-thinning effects. The influence of the type of media (phosphate buffer (PB), phosphate-buffered saline (PBS), Dulbecco’s modified Eagle’s medium (DMEM)) on the hydrogel properties was also explored and discussed. The 4 wt % NaALG-g-P(NIPAM80-co-NtBAM20)/DMEM formulation showed excellent shear-induced injectability at room temperature and instantaneous thermo-induced gel stiffening at body temperature, rendering it a good candidate for cell transplantation potential applications.

scholarly journals Comparison of the Ionic Conductivity Properties of Microporous and Mesoporous MOFs Infiltrated with a Na-Ion Containing IL Mixture

2020 ◽  
Author(s):  
Joshua Tuffnell ◽  
Jędrzej K. Morzy ◽  
Rui Tan ◽  
Qilei Song ◽  
Caterina Ducati ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Ionic Conductivities ◽  
Zeolitic Imidazolate Framework ◽  
Hierarchically Porous ◽  
Framework Materials ◽  
Sol Gel Synthesis

IL@MOF (IL: ionic liquid; MOF: metal-organic framework) materials have been proposed as a candidate for solid-state electrolytes, combining the inherent non-flammability and high thermal and chemical stability of the ionic liquid with the host-guest interactions of the MOF. In this work, we compare the structure and ionic conductivity of a sodium ion containing IL@MOF composite formed from a microcrystalline powder of the zeolitic imidazolate framework (ZIF), ZIF-8 with a hierarchically porous sample of ZIF-8 containing both micro- and mesopores from a sol-gel synthesis. Although the crystallographic structures were shown to be the same by X-ray diffraction, significant differences in particle size, packing and morphology were identified by electron microscopy techniques which highlight the origins of the hierarchical porosity. After incorporation of Na0.1EMIM0.9TFSI (abbreviated to NaIL; EMIM = 1-ethyl-3-methylimidazolium; TFSI = bis(trifluoromethylsulfonyl)imide), the hierarchically porous composite exhibited a 40 % greater filling capacity than the purely microporous sample which was confirmed by elemental analysis and digestive proton NMR. Finally, the ionic conductivity properties of the composite materials were probed by electrochemical impedance spectroscopy. The results showed that despite the 40 % increased loading of NaIL in the NaIL@ZIF-8micro sample, the ionic conductivities at 25 °C were 8.4x10-6 and 1.6x10-5 S cm-1 for NaIL@ZIF-8meso and NaIL@ZIF-8micro respectively. These results exemplify the importance of the long range, continuous ion pathways contributed by the microcrystalline pores, as well as the detrimental effect of discontinuous and tortuous mesoporous pathways which show a limited contribution to the overall ionic conductivity. <br>

Characterization of New Ionically Conducting Peo-Based Networks by Diffusion, Elasticity Modulus and Ionic Conductivity Measurements

1992 ◽  
Vol 293 ◽  
Author(s):  
Herve Cheradame ◽  
F. Desbat ◽  
P. Mercier-Niddam ◽  
S. Boileau
Keyword(s):  
Diffusion Coefficient ◽  
Ionic Conductivity ◽  
Elasticity Modulus ◽  
Sol Gel ◽  
Cation Transport ◽  
Lithium Cation ◽  
Conductivity Measurements ◽  
Conducting Materials ◽  
Diffusion Studies

AbstractIonically conducting materials containing PEO were prepared from telechelic di(methyl-diethoxy-silane) PEO, synthesized by the hydrosilylation of telechelic diallyl-PEO with methyldiethoxysilane. The network is obtained by the usual sol-gel chemistry. Then, it is filled with LiClO4 by diffusion of the salt and further drying. A comparison is made with the same kind of materials crosslinked using urethane chemistry. Diffusion studies show that the diffusion coefficient of solvent is similar for both types of materials, whilst the ionic conductivity is higher for the networks crosslinked with siloxane bonds. An experiment of diffusion of LiClO4 without solvent showed that this salt has a diffusion coefficient of the order of 2.10-8 cm2.sec-1 at 34°C. The conductivity calculated from this determination is compatible with the mechanism of lithium cation transport by the diffusion of salt molecules. Elasticity modulus measurements show that the salt aggregates are essentially located within the crosslinks at low concentration, but also in the PEO chains for salt concentrations higher than 1 mol/l.

scholarly journals Using Reverse Osmosis Membrane at High Temperature for Water Recovery and Regeneration from Thermo-Responsive Ionic Liquid-Based Draw Solution for Efficient Forward Osmosis

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 588
Author(s):  
Eiji Kamio ◽  
Hiroki Kurisu ◽  
Tomoki Takahashi ◽  
Atsushi Matsuoka ◽  
Tomohisa Yoshioka ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
High Temperature ◽  
Energy Saving ◽  
Osmotic Pressure ◽  
Reverse Osmosis ◽  
Forward Osmosis ◽  
Solution Temperature ◽  
Water Recovery ◽  
Temperature Dependent ◽  
Draw Solution

Forward osmosis (FO) membrane process is expected to realize energy-saving seawater desalination. To this end, energy-saving water recovery from a draw solution (DS) and effective DS regeneration are essential. Recently, thermo-responsive DSs have been developed to realize energy-saving water recovery and DS regeneration. We previously reported that high-temperature reverse osmosis (RO) treatment was effective in recovering water from a thermo-responsive ionic liquid (IL)-based DS. In this study, to confirm the advantages of the high-temperature RO operation, thermo-sensitive IL-based DS was treated by an RO membrane at temperatures higher than the lower critical solution temperature (LCST) of the DS. Tetrabutylammonium 2,4,6-trimethylbenznenesulfonate ([N4444][TMBS]) with an LCST of 58 °C was used as the DS. The high-temperature RO treatment was conducted at 60 °C above the LCST using the [N4444][TMBS]-based DS-lean phase after phase separation. Because the [N4444][TMBS]-based DS has a significantly temperature-dependent osmotic pressure, the DS-lean phase can be concentrated to an osmotic pressure higher than that of seawater at room temperature (20 °C). In addition, water can be effectively recovered from the DS-lean phase until the DS concentration increased to 40 wt%, and the final DS concentration reached 70 wt%. From the results, the advantages of RO treatment of the thermo-responsive DS at temperatures higher than the LCST were confirmed.

scholarly journals Fabrication and Analysis of Near-Field Electrospun PVDF Fibers with Sol-Gel Coating for Lithium-Ion Battery Separator

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 186
Author(s):  
Mark D. Francisco ◽  
Cheng-Tang Pan ◽  
Bo-Hao Liao ◽  
Mao-Sung Wu ◽  
Ru-Yuan Yang ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Specific Capacitance ◽  
Near Field ◽  
Sol Gel ◽  
Lithium Ion ◽  
Nonwoven Fabric ◽  
Electrospun Fibers ◽  
Gel Method ◽  
Sol Gel Method ◽  
Microtensile Testing

Environmental and economic concerns are driving the demand for electric vehicles. However, their development for mass transportation hinges largely on improvements in the separators in lithium-ion batteries (LIBs), the preferred energy source. In this study, innovative separators for LIBs were fabricated by near-field electrospinning (NFES) and the sol-gel method. Using NFES, poly (vinylidene fluoride) (PVDF) fibers were fabricated. Then, PVDF membranes with pores of 220 nm and 450 nm were sandwiched between a monolayer and bilayer of the electrospun fibers. Nanoceramic material with organic resin, formed by the sol-gel method, was coated onto A4 paper, rice paper, nonwoven fabric, and carbon synthetic fabric. Properties of these separators were compared with those of a commercial polypropylene (PP) separator using a scanning electron microscope (SEM), microtensile testing, differential scanning calorimetry (DSC), ion-conductivity measurement, cyclic voltammetry (CV), and charge-discharge cycling. The results indicate that the 220 nm PVDF membrane sandwiched between a bilayer of electrospun fibers had excellent ionic conductivity (~0.57 mS/cm), a porosity of ~70%, an endothermic peak of ~175 °C, better specific capacitance (~356 mAh/g), a higher melting temperature (~160 °C), and a stable cycle performance. The sol-gel coated nonwoven fabric had ionic conductivity, porosity, and specific capacitance of ~0.96 mS/cm., ~64%, and ~220 mAh/g, respectively, and excellent thermal stability despite having a lower specific capacitance (65% of PP separator) and no peak below 270 °C. The present study provides a significant step toward the innovation of materials and processes for fabricating LIB separators.

scholarly journals Upscaling of LATP synthesis: Stoichiometric screening of phase purity and microstructure to ionic conductivity maps

Ionics ◽  
2021 ◽  
Vol 27 (5) ◽  
pp. 2017-2025
Author(s):  
Nikolas Schiffmann ◽  
Ethel C. Bucharsky ◽  
Karl G. Schell ◽  
Charlotte A. Fritsch ◽  
Michael Knapp ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Sol Gel ◽  
Ion Conductivity ◽  
Process Window ◽  
Lithium Aluminum ◽  
Potential Candidate ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Battery Cell ◽  
Li Ion

AbstractLithium aluminum titanium phosphate (LATP) is known to have a high Li-ion conductivity and is therefore a potential candidate as a solid electrolyte. Via sol-gel route, it is already possible to prepare the material at laboratory scale in high purity and with a maximum Li-ion conductivity in the order of 1·10−3 s/cm at room temperature. However, for potential use in a commercial, battery-cell upscaling of the synthesis is required. As a first step towards this goal, we investigated whether the sol-gel route is tolerant against possible deviations in the concentration of the precursors. In order to establish a possible process window for sintering, the temperature interval from 800 °C to 1100 °C and holding times of 10 to 480 min were evaluated. The resulting phase compositions and crystal structures were examined by X-ray diffraction. Impedance spectroscopy was performed to determine the electrical properties. The microstructure of sintered pellets was analyzed by scanning electron microscopy and correlated to both density and ionic conductivity. It is shown that the initial concentration of the precursors strongly influences the formation of secondary phases like AlPO4 and LiTiOPO4, which in turn have an influence on ionic conductivity, densification behavior, and microstructure evolution.

scholarly journals Multiscale additive manufacturing of polymers using 3D photo-printable self-assembling ionic liquid monomers

2019 ◽  
Vol 4 (3) ◽  
pp. 580-585 ◽  
Author(s):  
Bineh G. Ndefru ◽  
Bryan S. Ringstrand ◽  
Sokhna I.-Y. Diouf ◽  
Sönke Seifert ◽  
Juan H. Leal ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Additive Manufacturing ◽  
Self Assembly ◽  
Low Cost ◽  
Low Resolution ◽  
Top Down ◽  
Bottom Up ◽  
Cost Approach ◽  
Self Assembling ◽  
Nanoscale Features

Combining bottom-up self-assembly with top-down 3D photoprinting affords a low cost approach for the introduction of nanoscale features into a build with low resolution features.

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