Free Volume Properties Research Articles

Eco-friendly non-fluorinated membranes for renewable energy storage

The European Union is studying the possibility of prohibiting the use of fluorinated-based materials which could limit the use of the most studied and used Nafion and Nafion-like membranes for any applications. Therefore, this study focuses on the preparation and performance evaluation of green, non-fluorinated proton exchange membranes in a chlor-alkali-based reversible electrochemical cell system for renewable energy storage applications. The membranes were prepared by casting and cross-linking of polyvinyl alcohol (PVA) with varying chitosan (CS) concentrations (5–20 wt%), followed by sulfonation using diluted sulfuric acid at room temperature. CS concentrations significantly influenced membrane's physicochemical properties, including ion exchange capacity, ionic conductivity, mechanical strength, and water uptake. Positron annihilation lifetime spectroscopy revealed a correlation between free volume properties and other membrane characteristics. A custom-designed 3D-printed electrochemical cell was developed, capable of operating in reversible mode (both electrolysis and fuel cell modes) with a zero-gap configuration. The PVA/CS (20 wt%) membrane outperformed Nafion, exhibiting a lower voltage (4 V vs. 6 V) in electrolysis mode at 50 mA cm⁻2 and a higher specific power density (2.7 vs. 1.9 mW cm⁻2 mgPt) in fuel cell mode. The obtained results demonstrate that crosslinked PVA/CS non-fluorinated based membranes can be sulfonated using diluted sulfuric acid and work effectively in reversible chlor-alkali electrochemical cells.

Effect of thermal pre‐compressing on ionic conductivity and mechanical properties of PEO‐based solid‐state electrolytes

AbstractPolyethylene oxide (PEO)‐based solid polymer electrolytes are regarded as promising electrolyte materials because of their safety and flexibility. However, low ionic conductivity at ambient temperature and poor mechanical properties have been a hindrance to its development. In this work, we thermally compressed the PEO‐based electrolytes and explored the ionic conductivity, mechanical performance, free volume, and thermal properties of the electrolyte under different thermal pre‐compressing strains (TPC‐strains). The results show that TPC‐strain can significantly improve the ionic conductivity, in‐plane strength, stiffness, and cell specific capacity as well as the mechanical integrity of solid polymer electrolytes within the battery environment. However, it also results in a reduction in the modulus and stiffness of the SPEs in the through‐plane. In particular, applying a TPC‐strain of 10%–20% to the SPEs by thermal compressing may be a suitable option, which can increase the ionic conductivity of the through‐plane to a factor of 3.4 compared with the uncompressed electrolyte, and increase the in‐plane strength by up to 141%, resulting in better mechanical integrity during charging/discharging processes. At the same time, the compression modulus can be maintained at 80% or higher.

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

AbstractPolymer electrolyte membranes (PEMs) play a vital role in electrochemical devices, facilitating ion conduction while blocking gases and electrons. Their effectiveness is closely linked to their microstructural properties, especially the free volume, which impacts ionic conductivity, mechanical strength, and overall device performance. This study examines the behavior of PVC/PMMA/SSA blends under electric fields, using Positron Annihilation Lifetime Spectroscopy (PALS) to assess free volume and dielectric properties. The study involved preparing and characterizing membranes through x‐ray diffraction (XRD), thermogravimetric analysis (TGA), and PALS. XRD results indicated semi‐crystalline structures with changes in intensity due to temperature variations, while TGA highlighted changes in thermal stability under different electric fields. PALS measurements showed that free volume varied with temperature and electric field strength, influencing the material's dielectric and mechanical characteristics. The results revealed that higher electric fields reduced free volume while enhancing dielectric properties. The dielectric constant and loss were found to depend on frequency, which was affected by the polar SO3H groups. Impedance spectroscopy provided further insights into the electrical properties, showing increased dc conductivity with stronger electric fields. A correlation between the free volume investigated from PAL and the electrical properties was observed. This study emphasizes the significance of free volume and external electric field in optimizing PEMs for advanced energy applications.

On the intermolecular interactions and mechanical properties of polyvinyl alcohol/inositol supramolecular complexes

Hydrogen-bond (H-bond) cross-linking has recently been proven a promising strategy for simultaneously improving strength, toughness, and ductility of H-bonded polymers. However, there has been a lack of a fundamental understanding of how H-bond cross-linking works on a molecular level. To fill this knowledge gap, coarse-grained (CG) simulation provides a possibility because of its high computational efficiency and access to longer lengths and time scales. However, existing coarse-grained force fields and potential functions exhibit an inability to accurately describe H-bonded polymer systems. Herein, we report a modified CG model to understand the H-bond crosslinking effect of small molecules, inositol (IN) on polyvinyl alcohol (PVA), with reference to MARTINI 3.0 parameters and empirical data. The simulation results show that incorporating IN molecules results in a significant improvement in the strength, ductility, and toughness of PVA, which is in good agreement with experimental data. Moreover, the modified CG model establishes a close correlation between IN content, water content, tensile rate and glass transition, free volume, chain movement and mechanical properties of PVA. The results show that the yield strength of PVA initially increases and then decreases with the addition of IN. The maximum yield stress of PVA at IN-1.0 is approximately 155 MPa, representing a 33% increase compared to that of PVA. Additionally, the glass transition temperature (Tg) reaches 80.2 °C, ∼2.8 °C higher than that of pure PVA. This work develops a modified CG model for understanding intermolecular interactions and mechanical properties of H-bonded polymer systems on a molecular level. This understanding is expected to help expediate the material design and properties optimization of strong and tough polymeric materials.

Ultrastrong and High-Tough Thermoset Epoxy Resins from Hyperbranched Topological Structure and Subnanoscaled Free Volume.

The strength and toughness of thermoset epoxy resins are generally mutually exclusive, as are the high performance and rapid recyclability. Experimentally determined mechanical strength values are usually much lower than their theoretical values. The preparation of thermoset epoxy resins with high modulus, high toughness, ultrastrong strength, and highly efficient recyclability is still a challenge. Here, novel hyperbranched epoxy resins (Bn, n = 6, 12, 24)with imide structures by a thiol-ene click reaction. Bn shows an excellent comprehensive function in simultaneously improving the strength, modulus, toughness, low-temperature resistance, and degradability of diglycidyl ether of bisphenol-A (DGEBA). All the mechanical properties first increase and then decrease with minimization of the free volume properties. The improvement is attributable to uniform molecular holes or free volume by a molecular mixture of linear and hyperbranched topological structures. The precise measurement and controllability of the molecular free volume properties of epoxy resins is first discovered, as well as the imide structure degradation of crosslinked epoxy resins. The two conflicts are successfully resolved between strength and toughness and between high performance during service and high efficiency during degradation. These findings provide a route for designing ultrastrong, tough, and recyclable thermoset epoxy resins.

Effect of Aromatic Rings in AESO-VDM Biopolymers on the Local Free Volume and Diffusion Properties of Polymer Matrix

In this work, the influence of aromatic rings on the local free volume of cured mixtures of acrylate epoxidized soybean oil (AESO) and vanillin dimethacrylate (VDM) was investigated. Cross-linking took place under the influence of UV light in the presence or absence of a photoinitiator. The local free volume and its homogeneity were characterized using the Positron Annihilation Lifetime Spectroscopy (PALS) technique. It was found that increasing the content of VDM, which contains aromatic rings, caused a decrease in the local free volume of the cured polymer network, with consequences for the diffusion properties of the polymer, which were tested for the case of water. Another consequence of increasing the content of VDM was a decrease in the conversion of double bonds in the finally cured samples, characterized by near-infrared spectroscopy (NIR). This finding illustrates a case where the decrease in free volume is not necessarily related to an increase in the crosslinking density of the polymer, but is a consequence of the presence of an increase in the occupied volume of aromatic rings in the volume of the polymer.

Detailed investigation on the insulation and permeability characteristics of rigid polyurethane foam loaded with micron-sized Turkey feather powder depending on the free volume change

This study brokes new ground to understand the insulation and permeability performances of rigid polyurethane foams (RPUFs) containing the different contents of micron-sized turkey feather powders (TFPs) depending on the free volume change for the first time. The effects of TFPs loading on the RPUFs were investigated by the examination of their structural and chemical features (particle size and ATR-FTIR analyses), free volume property (PALS analysis), insulation features (thermal conductivity and sound absorption tests), permeability performance (air and water vapor permeability tests) and cellular topology (SEM). PALS analysis results revealed that the addition of TFPs into the foams led to the sharp decrease in all free volume parameters since TFPs caused the formation of the disordered cells by occupying the holes in the matrix. Furthermore, both thermal conductivity and acoustic performance of the resulting foams get worse when compared to unfilled RPUF. This results were attributed to the formation of thinner and weaker cells during polymerization, reduction in the amount of CO2 inside the cells, enhancement in the solid-phase level in the matrix due to the increasing of volumetric density. Additionally, the foam samples with high content of TFPs showed considerably lower air and water vapor permeabilities when compared to neat RPUFs due to the dominant hydrophobic character of the keratin and reduction in the degree of vacancies in the matrix. SEM analysis also revealed that TFPs showed good compatibility with RPUF, but the distorted and irregular shaped cellular morphology was obtained at high contents.

Fluorination as a powerful tool for improving water/salt selectivity of hydrophilic polyethersulfone

Fluorination is an important tool for tuning polymer free volume properties, but the effect of fluorination on the water/salt transport properties of desalting polymers remains uncertain. In this work, a series of novel cysteine-based polyethersulfones (PES-Cys and PES-Cys-2F, PES-Cys-6H and PES-Cys-6F, PES-Cys-8H, and PES-Cys-8F) were designed in pair (4,4'-difluorodiphenyl sulfone versus 3,3',4,4'-tetrafluorodiphenyl sulfone, bisphenol A versus hexafluorobisphenol A, and 4,4'-dihydroxybiphenyl versus decafluorobiphenyl). Upon casting into membranes via the solvent evaporation method, the membranes/polymers were characterized by 1H NMR, FTIR, XRD, DSC, Zeta potential, and the water/salt transport properties of the membranes was investigated systematically. It has been demonstrated that fluorination brings out greater spatial site resistance, stronger hydrophobicity, and higher electronegativity to polyethersulfone chains, leading to decreased water sorption but increased salt sorption. Fluorinated polyethersulfone displayed higher water diffusion coefficient because the C–F group can shatter water clusters into water molecules, which can diffuse more rapidly. Fluorinated polyethersulfone exhibit superior water/salt selectivity, with the most rigid PES-Cys-8F of the highest fluorine content showing water/salt selectivity over the empirical upper bound line. The enhanced water/salt selectivity is mostly because that fluorination improves water permeability by significantly increasing the water diffusion coefficient, while the electrostatic barrier provided by the electronegative fluorine atoms inhibits salt diffusion. This study provides valuable theoretical guidance for future molecular design of antioxidant desalting polymers.

Thermal aging mechanism of PBT energetic elastomer based on the evolution of microstructure

3,3-bis(azidomethyl) oxetane and tetrahydrofuran copolymer (PBT)-based thermosetting polyurethane is an ideal energetic elastic matrix for high-energy, low-smoke, and insensitive solid propellants used in the field of aeronautics and aerospace. Its aging during long-term storage will cause deterioration of the mechanical properties of the propellant, which will bring serious security risks when working. To explore the thermal aging mechanism, the PBT elastomer was prepared and then aged at 40 °C, 60 °C, and 70 °C. Starting from characteristic structures that affect the mechanical properties of elastomer, active groups, hydrogen bonds, chemical crosslinking, free volume, crystallization, microphase separation, and mechanical properties of the PBT elastomer during thermal aging were analyzed by fourier transform-infrared (FT-IR) spectroscopy, swelling method, positron annihilation lifetime spectrum (PALS), X-ray diffraction (XRD), dynamic mechanical analysis (DMA), and uniaxial tensile test, respectively. Here, we found that the thermal aging of the PBT elastomer was a coupling process of several aging effects and showed a segmented feature. Destruction of hydrogen bonds, degradation of urethanes and oxidative crosslinking between polyether backbones successively dominated the thermal oxidation process of the PBT elastomer. This work is of great significance for the development of antiaging technologies for the PBT propellant and lays the foundation for the establishment of a mechanical property deterioration model based on microstructure evolution.

Experimental investigation of the structural features of polycarbonate (PC) filled with bismuth nitrate pentahydrate (BNP) composite films in terms of free volume defects probed by positron annihilation lifetime spectroscopy

The effect of bismuth nitrate pentahydrate (BNP) on the properties and microstructural features of polycarbonate (PC) has been investigated using PALT, XRD, SEM, EDX, TG, ATR-FTIR and tensile mechanical measurements. Positron Annihilation Lifetime Spectroscopy reveals that the ortho-positronium lifetime and its corresponding intensity significantly decrease as the filler level of BNP in PC (in the composite) increases from 0.3 wt% up to 5.0 wt%. This is due to the increasing fraction of positrons that annihilate with the filler particles and also in the interfacial layers of the filler and the host polymer. Fourier Transform Infrared spectra show that there is no significant shift in the IR bands of the composite when compared to those of pure PC, and so there is little molecular level interaction between PC and BNP. The micrographs of SEM revealed a random distribution of filler particles in the composite, and there is the formation of agglomerates of BNP at higher filler levels. There is an increase in the degree of crystallinity of the composite films due to the addition of the crystalline filler, which was confirmed by XRD analysis. Tensile mechanical tests confirmed the improved tensile strength of prepared composites at lower and moderate filler levels, from 0.0 wt % up to 2.5 wt%. The free volume properties of the composite films are correlated with its tensile mechanical properties.

Study of modified PVDF membranes with high-capacity adsorption features using Quantum mechanics, Monte Carlo, and Molecular Dynamics Simulations

Petrochemical wastewater should be appropriately handled to avoid pollution in natural water. A current research field in this area is to use super hydrophilic membranes with simultaneous superoleophobicity for separating emulsified oil from water. In this study, molecular simulations approaches such as molecular dynamics (MD), Monte Carlo (MC), and quantum mechanics (QM) simulations were used to scrutinize the behavior of adsorption capacities of neat and modified PVDF membranes. For this, PVDF grafted with N-isopropylacrylamide (NIPAAm), azobisisobutyronitrile (AIBN) and also blended with different weight percentages of poly[oligo(ethylene glycol) methacrylate] (PEGMA)-g-1-butyl-3-vinyl imidazolium bromide (BVIm-Br) (PEGMA-co-BVIm-Br) copolymer, as a super hydrophilic agent, to create different membranes compositions. It has been demonstrated in QM simulations that the PVDF-(PEGMA-co-BVIm-Br)-Water-oil configurations facilitate electron transfer more effectively than the other configurations. This makes PVDF-(PEGMA-co-BVIm-Br) a suitable adsorbent for water compared to the neat PVDF. Moreover, the adsorption energy of adsorbates on the membranes with different compositions as adsorbents was estimated using the MC method via Adsorption Locator of Materials Studio (MS) software. Based on the results from the MC simulations, more water molecules were adsorbed into the membrane structure when the hydrophilic agent (PEGMA-co-BVIm-Br) was added to it, which indicates a greater degree of hydrophilicity. Finally, MD simulations were employed to consider the hydrophilic agent effect (PEGMA-co-BVIm-Br) on the physicochemical properties of the membrane structures, such as X-ray diffraction (XRD) pattern, glass transition temperature (Tg), cohesive energy density (CED), fractional free volume (FFV), solubility parameters (δ), and mechanical properties.

Microstructural study of different thick dimethacrylate-based samples using different amounts of photoinitiator

The influence of the thickness and concentration of photoinitiator on the free volume properties of a dental material based on dimethacrylate was investigated in situ by positron annihilation lifetime spectroscopy.

CO2 Capture Improvement in Polyetherimide Membranes: Effect of Ionic Liquid on the Molecular Mobility

The research described here was aimed at the development of polymeric membranes based on polyetherimide (PEI) containing the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium hexafluorophosphate ([BMMIM]PF6). The preparation of the PEI-based membranes was carried out via casting of solutions with the incorporation of the IL. The prepared membranes were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for thermal and free volume properties. CO2 sorption and permeation properties were measured to evaluate the CO2 capture performance of the membranes. The fractional free volume (FFV) of the membranes was around 15%. The incorporation of IL increased the CO2 sorption capacity, promoting an increase of 330% in the solubility coefficient (KD) and resulted in a decrease of 96% in CO2 permeability when compared to the control membrane. The presence of IL in the PEI matrix significantly altered the structural and transport characteristics of the analyzed membranes, being efficient for CO2 capture, as they showed a high CO2 solubility and a decrease in CO2 permeation.

Synthesis and Characterization of Polyimides with Naphthalene Ring Structure Introduced in the Main Chain.

In this paper, a new aromatic diamine monomer 4,4'-(2,6-naphthalenediyl)bis[benzenamine]) (NADA) was synthesized and a series of modified PI films containing naphthalene ring structure obtained by controlling the molar ratio of NADA monomer, ternary polymerization with 4,4'-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). The effects of the introduction of the naphthalene ring on the free volume and various properties of PI were investigated by molecular dynamic simulations. The results show that the comprehensive properties of the modified films are all improved to some extent, with 5% thermal weight loss temperature (Td5%) of 569 °C, glass transition temperature (Tg) of 381 °C, tensile strength of 96.41 MPa, and modulus of elasticity of 2.45 GPa. Dielectric property test results show that the dielectric constant (Dk) of the film at 1 MHz is reduced from 3.21 to 2.82 and dielectric loss (Df) reduced from 0.0091 to 0.0065. It is noteworthy that the PI-1 dielectric constant is reduced from 3.26 to 3.01 at 10 GHz with only 5% NADA doping, which is expected to yield the best ratio and provide the possibility of industrial production.

Role of side-chain length on gas transport of CO2/CH4 mixtures in polymers with side-chain porosity

Polymers of intrinsic microporosity (PIMs) are traditionally formed from ladder backbones, but recent synthetic advances have allowed for the formation of non-traditional PIMs using a poly(ladder) motif, whereby rigid PIM-like sidechains are appended onto more flexible backbones. The effect of side-chain length on free volume and gas transport properties was recently evaluated for a methoxy-functionalized poly(ladder) (OMe-ROMP). In this study, we elaborate on the role of side-chain length and its influence on mixed-gas performance and plasticization stability for OMe-ROMP. Pure-gas sorption results are also reported, including hysteresis effects from CO2 conditioning. Taken together, this study reveals the role of side-chain length on gas sorption, diffusion, and plasticization for CO2/CH4 separations. We conclude that the length of a rigid side chain in the poly(ladder) motif is a valuable structural parameter to control sorption, diffusion, and stability towards plasticization for gas separation membrane materials.

Performance of SiO2 Filled Functional Polypropylene Substrates for 5th Generation Communication

Three grades of functional polypropylene (FPP)/silica (SiO2) (FPPASP16 xSiO2 y, FPPASP17 xSiO2 y and FPPASP18 xSiO2 y) and their crosslinked FPP/SiO2 (CLFPPASP16 xSiO2 y, CLFPPASP17 xSiO2 y and CLFPPASP18 xSiO2 y) nanocomposites were satisfactorily made for applying as fifth generation (5 G) mobile communication substrates. Significantly smaller linear thermal expansion coefficient (LCTE) but larger dielectric constant (εr), dielectric loss (tan δ) and onset degradation temperature (DTonset) were acquired for CLFPPa xSiO2 y than those of the corresponding FPPa xSiO2 y sequence having identical SiO2 loadings. It is worth emphasizing that substantially smaller εr, tan δ and LCTE values were acquired for every FPPa xSiO2 y and CLFPPa xSiO2 y sequence filled with appropriate SiO2 loadings. Quite small εr/tan δ ( 2.41/0.00539, 2.36/0.00361, 2.53/0.00653, 2.52/0.00671, 2.46/0.00461 and 2.62/0.00821, all measured at 1 MHz) and LCTE (∼140 ppm/°C, 152 ppm/°C, 75 ppm/°C, 127 ppm/°C, 142 ppm/°C and 56 ppm/°C) values suitable for 5 G communication were acquired for FPPASP16 95SiO2 5, FPPASP17 94SiO2 6, FPPASP18 95SiO2 5, CLFPPASP16 95SiO2 5, CLFPPASP17 94SiO2 6 and CLFPPASP18 95SiO2 5 filled with optimum loadings of SiO2 nanoparticles, respectively. All free volume properties estimated for every FPPa xSiO2 y and CLFPPa xSiO2 y sequence enlarged to a largest value as the SiO2 loadings approached the corresponding optimum value. Possible reasons accounting for these substantially diminished dielectric and LCTE and improved thermal degradation properties of the FPPa xSiO2 y and CLFPPa xSiO2 y films are proposed.

Free volume and gas transport properties of hydrolyzed polymer of intrinsic microporosity (PIM-1) membrane studied by positron annihilation spectroscopy

In this work, a series of hydrolyzed polymers of intrinsic microporosity (PIMs) membranes were successfully synthesized under alkaline conditions. Positron annihilation lifetime measurement is employed to analyze the pore structure of the hydrolyzed PIMs. In the original PIM-1, there are two kinds of pores, i.e. micropores with radius of 4.32 Å and ultramicropores with radius of 2.58 Å. The size of all the pores shows a continuous decrease with increasing hydrolysis time, which is confirmed by the reduced chain-to-chain spacing in the hydrolyzed PIMs measured by X-ray diffraction. Meanwhile, the fractional free volume also shows decrease after the hydrolysis process, while the relative number of ultramicropores increases. Benefiting from the smaller pore size in the hydrolyzed PIMs membrane, the gas molecules with smaller size (such as CO 2 ) can be separated more efficiently. The selectivity of CO 2 /CH 4 of hydrolyzed PIMs reaches up to 30.05 with a relatively high CO 2 permeability of 140.58 Barrer, which exceeds the Robeson’s 1991 upper bound. Our results indicate that the hydrolyzed polymers of intrinsic microporosity membranes are promising candidates for gas separation membrane in the future. • A series of hydrolyzed PIMs membranes were synthesized under alkaline conditions. • The process shortens the reaction time and improves the gas separation performance. • The logarithm of P shows a linear relationship with 1/FFV. • Positron lifetime measurements indicate the free volume adjusts the selectivity.

Synergistic effect of thermal crosslinking and thermal rearrangement on free volume and gas separation properties of 6FDA based polyimide membranes studied by positron annihilation

Two kinds of polyimide membranes 6F-AP and 6F-AP/DA (APAF:DABA=3:2) were synthesized and heated between 300–450 °C to study the effect of thermal treatment on the chain structure and gas transport performance of membranes. Fourier Transform Infrared (FI-IR) and X-ray diffraction (XRD) measurements show that heating causes rearrangement of polyimide into rigid polybenzoxazole which prevents the effective stacking of polymer chains leading to the increase of d-spacing and fractional free volume. Positron annihilation results confirm the increase of both size and number of free volume due to the thermal rearrangement. The addition of DABA monomer into 6F-AP causes crosslinking during heating, which results in tightening of the rigid chain spacing of benzoxazole, thus leading to slight decrease in the size and number of free volume. The increase in fraction free volume induced by thermal rearrangement can significantly improve the gas permeability of 6F-AP series membranes, which increases from 16.2 and 3.9 barrer to 271.4 and 200.3 barrer for H2 and CO2, respectively, after increasing the heating temperature from 300 to 450 °C. But this is accompanied by a decrease in gas selectivity due to the increase in free volume size. Finally, by careful tailoring the free volume structure through thermal rearrangement and crosslinking, the 6F-AP/DA polyimide treated at 400 °C exhibits a H2 permeability of 196.4 barrer and a H2/CH4 ideal selectivity of 90, which is above the 2008 Robeson upper bound. Our results indicate that by designing the functional groups of the reaction monomer plus appropriate thermal treatment, the microstructure of polyimide membrane can be effectively adjusted for high-performance gas separation.

CF3-MOF enhanced pervaporation selectivity of PDMS membranes for butanol separation

Direct separating butanol from fermentation broth via pervaporation is considered as the most effective method to realize solvent enrichment, which is dominated by membranes. Herein, MOF (MAF-9) with CF3 group is doped into PDMS matrix to enhance the butanol pervaporation, especially selectivity. The super-hydrophobicity of MAF-9 caused by CF3 groups allows the preferential adsorption and permeation for butanol molecules, thus increasing the membrane selectivity; while its appropriate pore diameter renders the exquisite diffusion pathways towards the butanol molecules, thus increasing the membrane flux. Results show that the loading-optimized MAF-9/PDMS MMM has 53 of separation factor and 848 g m−2 h−1 of membrane flux, which are increased by 24% and 16%, respectively, compared with pure PDMS membrane. TGA, FT-IR, BET, and XRD are conducted to characterize the thermal stability, morphology and structure of MAF-9; PALS, SEM, AFM, SD and TGA are tested to evaluate the free volume property, morphology, adsorption capacity and thermal stability of membranes, respectively. Conditions including particle loading, feed temperature and feed concentration are also optimized in this study.

A scalable ball milling strategy to endow SnS anode electrodes with free volume property for enhanced electrochemical performance

SnS/G-x% anode with free volume has been fabricated by a scalable ball milling technology. The free volume effectively relief the volume expansion/shrinkage SnS, an optimized electrochemical performance is being made at graphite content of 15 wt%.