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Membrane technologies and materials development appear crucial for the hydrogen/natural gas separation in the impending transition to the hydrogen economy. Transporting hydrogen through the existing natural gas network could result less expensive than a brand-new pipe system. Currently, many studies are focused on the development of novel structured materials for gas separation applications, including the combination of various kind of additives in polymeric matrix. Numerous gas pairs have been investigated and the gas transport mechanism in those membranes has been elucidated. However, the selective separation of high purity hydrogen from hydrogen/methane mixtures is still a big challenge and nowadays needs a great improvement to promote the transition towards more sustainable energy source. In this context, because of their remarkable properties, fluoro-based polymers, such as PVDF-HFP and NafionTM, are among the most popular membrane materials, even if a further optimization is needed. In this study, hybrid polymer-based membranes were deposited as thin films on large graphite surfaces. Different weight ratios of PVDF-HFP and NafionTM polymers supported over 200 μm thick graphite foils were tested toward hydrogen/methane gas mixture separation. Small punch tests were carried out to study the membrane mechanical behaviour, reproducing the testing conditions. Finally, the permeability and the gas separation activity of hydrogen/methane over membranes were investigated at room temperature (25 °C) and near atmospheric pressure (using a pressure difference of 1.5 bar). The best performance of the developed membranes was registered when the 4:1 polymer PVDF-HFP/NafionTM weight ratio was used. In particular, starting from the 1:1 hydrogen/methane gas mixture, a 32.6% (v%) H2 enrichment was measured. Furthermore, there was a good agreement between the experimental and theoretical selectivity values.

The current research is devoted to fabricating a superhydrophobic coating on alumina surfaces via a facile one-step electrospinning technique. The wettability properties of the as-prepared coating were investigated. The polymeric coatings exhibited a water contact angle (WCA) of about 152° ± 3 and a sliding angle (SA) is 4 ± 2°. However, a WCA of 154 ± 2° and a SA of 3 ± 2° were recorded after the addition of Al2O3 nanoparticles. The wettability of the prepared coatings has also been inspected after exposure to intense UV irradiation of 0.89 W/(m2 nm) and high-temperature degree of 60 °C, for 500 h. It was found that the measured WCA and water contact hysteresis (WCAH) for the poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP/Al2O3 nanocomposite 150 ± 1° and 10 ± 1° compared with 122 ± 4° and 22 ± 4° of pure PVDF-HFP, respectively. The morphology of the superhydrophobic coating was explored, illustrating the construction of a beaded fiber structure. The surface roughness of the fabricated super water-repellent coatings was recorded using an atomic force microscope (AFM). The electrochemical behavior of superhydrophobic coating was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl solution before and after exposure to UV radiation. The research outcomes promote a one-step fabrication technique to prepare polymeric superhydrophobic coatings with good resistance for corrosion and degradation under UV irradiation.

Growing environmental concerns are stimulating researchers to develop more and more efficient materials for environmental remediation. Among them, polymer-based hierarchical structures, attained by properly combining certain starting components and processing techniques, represent an emerging trend in materials science and technology. In this work, graphene oxide (GO) and/or carbon nanotubes (CNTs) were integrated at different loading levels into poly (vinyl fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and then electrospun to construct mats capable of treating water that is contaminated by methylene blue (MB). The materials, fully characterized from a morphological, physicochemical, and mechanical point of view, were proved to serve as membranes for vacuum-assisted dead-end membrane processes, relying on the synergy of two mechanisms, namely, pore sieving and adsorption. In particular, the nanocomposites containing 2 wt % of GO and CNTs gave the best performance, showing high flux (800 L × m−2 h−1) and excellent rejection (99%) and flux recovery ratios (93.3%), along with antifouling properties (irreversible and reversible fouling below 6% and 25%, respectively), and reusability. These outstanding outcomes were ascribed to the particular microstructure employed, which endowed polymeric membranes with high roughness, wettability, and mechanical robustness, these capabilities being imparted by the peculiar self-assembled network of GO and CNTs.

In order to improve the multifunctionality of polymer composites for advanced applications a novel tri-composite material is presented based on the inclusion of MFI zeolite and the ionic liquid (IL) 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) in an electroactive poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. Tri-composites were produced by solvent casting with a relative overall filler content up to 40 wt.%. A compact film morphology is obtained, and the polymer degradation temperature and degree of crystallinity are independent on the filler content and type. On the other hand, the polymer crystalline phase depends on the presence of the IL but is independent of its content. Regarding the mechanical properties, it is observed that the IL has a plasticizing effect with a significant contribution to the reduction of the Young's modulus from 151 MPa for the pristine polymer to 92 MPa for the 30 wt.%/10 wt.% IL/MFI content sample. A high ionic conductivity value at room temperature of 3.9 × 10−5 S.cm−1 was obtained for the tri-composite with the highest IL content (30 wt.%/10 wt.% IL/MFI). The tri-composite system was studied as solid polymer electrolyte (SPE) for battery and bending actuator applications, demonstrating the multifunctionality of the material. The sample with the best cycling performance was observed for the highest MFI content (10 wt.%/30 wt.% IL/MFI) with a discharge capacity value of 110 mAh.g−1 and maintaining almost 80% of its initial capacity after 30 cycles at the C/10 rate. Regarding to the bending performance, the best bending actuation was detected for highest IL content (30 wt.%/10 wt.% IL/MFI), related to the ionic conductivity of the sample. Thus, it is demonstrated that the new tri-composite system, due to its tunable characteristics as a function of the relative IL and zeolite contents, is suitable for a next generation of multifunctional polymer composite materials for advanced applications., The authors thank FCT (Fundaçã para a Ciência e a Tecnologia) for financial support under the framework of Strategic Funding grants UIDB/04650/2020, UID/FIS/04650/2021, UID/EEA/04436/2021 and UID/QUI/0686/2021; and support from FEDER funds through the COMPETE 2020 Programme (projects PTDC/FIS-MAC/28157/2017 and POCI-01-0145-FEDER-007688) and MIT-EXPL/TDI/0033/2021, POCI01-0247-FEDER-046985. Grants SFRH/BD/140842/2018 (J.C.B.), 2021.07361.BD (R.S.P.), and SFRH/BPD/121526/2016 (D.M.C) and contracts under the Stimulus of Scientific Employment, Individual Support CEECIND/00833/2017 (R.G.) and 2020.04028 CEECIND (C.M. C.) are acknowledged. Financial support from the Basque Government under the ELKARTEK program is also acknowledged.

Lithium-ion batteries are popular energy storage devices due to their high energy density. Solid electrolytes appear to be a potential replacement for flammable liquid electrolytes in lithium batteries. This inorganic/hybrid solid electrolyte is a composite of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, (poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) polymer and sodium superionic conductor (NASICON)-type Li1+xAlxTi2−x(PO4)3 (LATP) ceramic powder. The structure, morphology, mechanical behavior, and electrochemical performance of this composite solid electrolyte, based on various amounts of LiTFSI, were investigated. The lithium-ion transfer and conductivity increased as the LiTFSI lithium salt concentration increased. However, the mechanical strength apparently decreased once the percentage of LITFSI was over 60%. The hybrid electrolyte with 60% LiTFSI content showed high ionic conductivity of 2.14 × 10−4 S cm−1, a wide electrochemical stability window (3–6 V) and good electrochemical stability. The capacity of the Li|60% LiTFSI/PVDF-HFP/LATP| LiFePO4 solid-state lithium-metal battery was 103.8 mA h g−1 at 0.1 C, with a high-capacity retention of 98% after 50 cycles.

Poly(vinylidene fluoride) (PVDF) and its copolymers exhibit excellent piezoelectric properties and are potential materials for high efficiency energy harvesting devices. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films are prepared by the solution casting method. The prepared film is then subjected to mechanical stretching and poling process. By adjusting the temperature of the poling process and the elongation ratio of the mechanical stretching process, the relative content of β-phase F(β) increases significantly, leading to high piezoelectric performance. The maximum output voltage of the PVDF-HFP films poled at 40°C reaches 3.67 V, 71% higher than that of the films poled at room temperature. Fourier transform infrared spectroscopy analysis (FTIR), XRD (X-ray diffraction), and differential scanning calorimetry are used to investigate the influences of mechanical stretching and poling process on the crystal structure to discover the enhancement mechanism. This work provides a straightforward and low-cost route to prepare high piezoelectric PVDF-HFP-based materials.

In this work, electrospun yarns were produced by a nanofiber yarn spinning machine with a conical collector. In the first part, two different polymers (PAN and PVDF-HFP) were used in nanofiber yarn spinning with two different types of conical collector which are made of stainless steel and aluminium. In the second part, four different types of aluminium collector having different wall thickness and surface properties were used. For all yarns produced, the effect of different parameters has been analyzed in terms of fibre fineness distribution, yarn fineness and yarn linear density, yarn strength and breaking elongation. The results show that yarns produced by using aluminium collector are finer and have higher strength compare to the ones produced by stainless steel collector while PVDF-HFP nanofiber yarns are finer and have higher tensile strength compare to PAN. The results also show that yarns get coarser while fibres get finer as the collector wall thickness is increased in general. Scientific and Technological Research Council of Turkey (TuBTAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [117M166] We would like to gratefully acknowledge Scientific and Technological Research Council of Turkey (TuBTAK) for its support (Project no: 117M166). We also would like to thank Dr. Ylmaz Guven for his support during electric field simulation.

[EN] In this study, two different non-ionic surfactants have been evaluated as a plasticizer in lithium polymer electrolytes and compared with an organic carbonate-based plasticizer. To that end, non-ionic surfactants with different molecular weight and structure have been selected (Triton? X-100 and Brij?L23) and compared with organic carbonates (EC:DEC1:1) as plasticizers in lithium polymer electrolytes. The effect of the plasticizer content, salt content and surfactant characteristics on properties such as ionic conductivity, thermal stability and electrochemical stability of lithium polymer electrolytes has been studied. The results obtained show that the non-ionic surfactants studied as plasticizers (Triton? X-100 and Brij?L23) give lithium polymer electrolytes with higher thermal and electrochemical stability than organic carbonates, thus making them promising plasticizers for lithium polymer electrolytes, especially for high voltage lithium-ion batteries. Surfactant structure could influence the ionic conductivity of the polymer electrolytes, with the linear surfactants being more suitable for this application., This research was funded by the Centro de Desarrollo Tecnologico Industrial-CDTI (ALMAGRID Project-CER-20191006) and by the Instituto Valenciano de Competitividad EmpresarialIVACE-FEDER (MATER Project-IMDEEA/2019/48)

Solid-state batteries (SSBs) are gaining attention as they promise to provide better safety and a higher energy density than conventional liquid electrolyte batteries. Solid polymer electrolytes (SPEs) are promising candidates due to their flexibility providing better interfacial contact between electrodes and the electrolyte. However, SPEs exhibit very low ionic conductivity at ambient temperatures, which prevents their practical use in batteries. Herein, a simple and effective technique of hot press rolling is demonstrated to improve ionic conductivity and, hence, the performance of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)-based solid polymer electrolyte. Applying hot press rolling to the electrolyte membrane induced structural changes in the grain boundaries, which resulted in a reduction in the crystallinity of the material and, hence, an increase in the amorphous phase of the material, which eased the movement of the lithium ions within the material. This technique also improved the surface of the membrane, making it homogeneous and smoother, which resulted in better interfacial contact between the electrodes and electrolyte. Electrochemical tests were carried out on electrolyte membranes treated with and without hot press rolling to evaluate the effect of the treatment. The hot pressed electrolyte membrane showed significant improvements in its ionic conductivity and transference number. The cycling performance of the LFP/Li batteries using a hot press rolled electrolyte was also evaluated, which gave a specific discharge capacity of 134 mAh/g at 0.1 C. These results demonstrate that hot press rolling can have a significant effect on the electrochemical performance of solid polymer electrolytes.

The demand for more efficient energy storage devices has led to the exponential growth of lithium-ion batteries. To overcome the limitations of these systems in terms of safety and to reduce environmental impact, solid-state technology emerges as a suitable approach. This work reports on a three-component solid polymer electrolyte system based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), the ionic liquid 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), and clinoptilolite zeolite (CPT). The influences of the preparation method and of the dopants on the electrolyte stability, ionic conductivity, and battery performance were studied. The developed electrolytes show an improved room temperature ionic conductivity (1.9 × 10–4 S cm–1), thermal stability (up to 300 °C), and mechanical stability. The corresponding batteries exhibit an outstanding room temperature performance of 160.3 mAh g–1 at a C/15-rate, with a capacity retention of 76% after 50 cycles. These results represent a step forward in a promising technology aiming the widespread implementation of solid-state batteries., FCT (Fundação para a Ciência e Tecnologia) for financial support under the framework of Strategic Funding grants UID/CTM/50025/2021, UID/FIS/04650/2021, UID/EEA/04436/2021 and UID/QUI/0686/2021; and support from FEDER funds through the COMPETE 2020 Programme (projects PTDC/FISMAC/28157/2017 and POCI-01-0145-FEDER-007688). Grants SFRH/BD/140842/2018 (J.C.B.) and SFRH/BPD/121526/2016 (D.M.C) and contracts under the Stimulus of Scientific Employment, Individual Support CEECIND/00833/2017 (R.G.) and 2020.04028 CEECIND (C.M.C.) are acknowledged. Financial support from the Basque Government under the ELKARTEK program, Basque University System Research Groups, IT-1290-19 and the University of the Basque Country (GIU18/197). is also acknowledged

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films incorporating 40 %wt. of different types of imidazolium ionic liquids (ILs) comprising different magnetic anions (tetrachloroferrate [FeCl4] - , tetrathiocyanatocobaltate [(SCN)4Co]2 - and tetrachlorocobaltate [CoCl4] - ) and imidazolium cation chain lengths 1-butyl-3-methyl imidazolium and 1-ethyl-3-methyl imidazolium, have been developed for humidity sensing applications. The influence of the different ILs into the morphology of the IL/PVDF-HFP composites has been evaluated, being observed a porous structure independently of the IL anion type and cation chain length. The inclusion of the ILs into PVDF-HFP induces the polymer crystallization into the electroactive β phase, being the increase more noticeable for PVDF-HFP/[Bmim][FeCl4], which reaches a β phase content of 85%. The degree of crystallinity slightly decreases with the incorporation of the filler, the incorporation of [Bmim]2[CoCl4], [Bmim]2[Co(SCN)4], and [Emim]2[Co(SCN)4] leading to a degree of crystallinity between 11 and 13%. A decrease in the thermal stability and the yield strength is observed in the hybrid samples with respect to neat PVDF-HFP, being this decrease more noticeable for the PVDF-HFP/[Bmim]2[Co(SCN)4] samples. Further, the highest magnetization has been obtained for the PVDF-HFP/[Bmim]2[Co(SCN)4] and PVDF-HFP/[Bmim][FeCl4] composites with similar filler concentrations. The suitability of the developed materials for humidity sensing has been evaluated by analysing the impedance variation with varying relative humidity from 30% to 85%. [Bmim]2[CoCl4]/PVDF-HFP displays the highest relative humidity (RH) sensing response of -2245 ±240 Ω/RH. Finally, the applicability of the developed hybrid IL/polymer composites has been demonstrated by the development of a real time breathing monitoring device., This work was supported by the Portuguese Foundation for Science and Technology (FCT) under strategic funding UIDB/04650/2020, UID/FIS/04650/2020, UID/QUI/0686/2020, UIDB/50006/2020, UIDP/50006/2020 and LA/P/0008/2020UIDB/50006/2020 and UIDP/50006/2020, project PTDC/FIS-MAC/28157/2017, and grants 2021.08158.BD (J. S.), SFRH/BD/145345/2019 (L.C.F.), SFRH/BD/131729/2017 (N.P), and Investigator FCT Contract 2020.02915.CEECIND (D.M.C) and 2020.04028.CEECIND (C.M.C.). The authors acknowledge funding by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RBC43/AEI/10.13039/501100011033. The authors also acknowledge funding from the Basque Government Industry Department under the ELKARTEK program. Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, EGEF and ESF) is gratefully acknowledged.

With the aim of increasing the mechanical and biological properties of different materials, a supercritical CO2 (SC-CO2) assisted technique was used to include a polymer with a natural origin (levan) in membranes of cellulose acetate (CA) and polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP). CA-levan membranes were characterized by interconnected pores ranging from 9 to 13 μm; due to levan addition, composite membranes increased their mechanical resistance and cells adhesion (from 8% to 30%). In the second system, the processing of a PVDF-HFP-DMSO-levan colloidal suspension system caused a morphological modification and the generation of a foam-like structure; a decrease of the mechanical resistance and an increase of cells adhesion (from 8% to 35%) were observed. Stress-strain responses for both systems were fitted using two different hyperelastic equations, Yeoh and Ogden; deviations from experimental data lower than 15% were obtained. In conclusion, SC-CO2 assisted process was able to generate composite structures with levan, accessible to the cells; i.e., transforming polymers like CA and PVDF-HFP in potentially useful materials for biological applications.

Anti-icing or passive strategies have undergone a remarkable growth in importance as a complement for the de-icing approaches or active methods. As a result, many efforts for developing icephobic surfaces have been mostly dedicated to apply superhydrophobic coatings. Recently, a different type of ice-repellent structure based on slippery liquid-infused porous surfaces (SLIPS) has attracted increasing attention for being a simple and effective passive ice protection in a wide range of application areas, especially for the prevention of ice formation on aircrafts. In this work, the electrospinning technique has been used for the deposition of PVDF-HFP coatings on samples of the aeronautical alloy AA7075 by using a thickness control system based on the identification of the proper combination of process parameters such as the flow rate and applied voltage. In addition, the influence of the experimental conditions on the nanofiber properties is evaluated in terms of surface morphology, wettability, corrosion resistance, and optical transmittance. The experimental results showed an improvement in the micro/nanoscale structure, which optimizes the superhydro-phobic and anticorrosive behavior due to the air trapped inside the nanotextured surface. In addi-tion, once the best coating was selected, centrifugal ice adhesion tests (CAT) were carried out for two types of icing conditions (glaze and rime) simulated in an ice wind tunnel (IWT) on both as-deposited and liquid-infused coatings (SLIPs). The liquid-infused coatings showed a low water adhesion (low contact angle hysteresis) and low ice adhesion strength, reducing the ice adhesion four times with respect to PTFE (a well-known low-ice-adhesion material used as a reference). Project RTI2018-096262-B-C41-MAITAI, funded by MCIN/AEI/10.13039/501100011033 and by ERDF 'A way of making Europe'. Grant PRE2019-090656: funded by MCIN/AEI/10.13039/501100011033 and by ESF 'Investing in your future'. Project PJUPNA1929 funded by MCIN/AEI/10.13039/501100011033 and by ERDF 'A way of making Europe' and by BEI.

Considering the high levels of materials used in the fields of electronics and energy storage systems, it is increasingly necessary to take into consideration environmental impact. Thus, it is important to develop devices based on environmentally friendlier materials and/or processes, such as additive manufacturing techniques. In this work, poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are prepared by direct-ink-writing (DIW) by varying solvent evaporation temperature and fill density percentage. Different morphologies for both polymers are obtained, including dense films and porous membranes, as well as different electroactive β-phase content, thermal and mechanical properties. The dielectric constant and piezoelectric d33 coefficient for dense films reaches up to 16 at 1 kHz and 4 pC N−1, respectively for PVDF-HFP with a fill density of 80 and a solvent evaporation temperature of 50 °C. Porous structures are developed for battery separator membranes in lithium-ion batteries, with a highest ionic conductivity value of 3.8 mS cm−1 for the PVDF-HFP sample prepared with a fill density of 100 and a solvent evaporation temperature of 25 °C, the sample showing an excellent cycling performance. It is demonstrated that electroactive films and membranes can be prepared by direct-ink writing suitable for sensors/actuators and energy storage systems., The authors thank the FCT (Fundação para a Ciência e Tecnologia) for financial support under the framework of Strategic Funding grants UID/CTM/50025/2021, UID/FIS/04650/2021, UID/EEA/04436/2021 and UID/QUI/0686/2021; and supported by FEDER funds through the COMPETE 2020 Programme under the project number PTDC/FIS-MAC/28157/2017 and POCI-01-0145-FEDER-007688. The authors also the grant SFRH/BD/140842/2018 (J.C.B.) and contracts under the Stimulus of Scientific Employment, Individual Support CEECIND/00833/2017 (R.G.) and Contract 2020.04028.CEECIND (C.M.C.). The authors thank funding by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43 / AEI / 10.13039/501100011033 and from the Basque Government under the ELKARTEK, HAZITEK and PIBA (PIBA-2018-06) programs is also acknowledged.

In this research, the influences of the addition of PVP to PVDF-HFP polymers and the preparation of thin films using a solvent casting method were studied. The PVDF-HFP and polymer blend PVDF-HFP/PVP thin films with a nanostructured surface were investigated using scanning electron microscopy, differential scanning calorimetry, nanoindentation, and dielectric spectroscopy. The results showed that the PVP formed a dispersed phase (the poorer conductive islands) in the PVDF-HFP polymer matrix, which reduced its mechanical properties. The crystallinity of PVDF-HFP polymer decreased with the addition of PVP by 7.4%, but the PVP induced the formation of the polar β-phase of PVDF-HFP. Therefore, an improved dielectric response is expected, but it was not significantly improved even though the polar β-phase was detected. The contrasting effect was attributed to less conductive PVP islands on the surface of the PVDF-HFP/PVP polymer blend, which decreased its conductivity.

Gel polymer electrolytes have the advantages of both a solid electrolyte and a liquid electrolyte. As a transitional product before which a solid electrolyte can be comprehensively used, gel polymer electrolytes are of great research value. They can reduce the risk of spontaneous combustion and explosion caused by leakage during the use of conventional liquid electrolytes. Poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF–HFP), a material with excellent performance, has been widely utilized in the preparation of gel polymer electrolytes. Here, PVDF–HFP-based gel polymer membranes with polyvinyl pyrrolidone (PVP) pores were prepared using a phase inversion method, and Octavinyl-polyhedral oligomeric silsesquioxane (OVAPOSS) was doped to improve its temperature resistance as well as its ionic conductivity, to enhance its safety and electrochemical performance. The final prepared polymer membrane had a porosity of 85.06% and still had a certain mechanical strength at 160 °C without any shrinkage. The gel polymer electrolyte prepared with this polymer membrane had an ionic conductivity of 1.62 × 10−3 S·cm−1 at 30 °C, as well as an electrochemical window of about 5.5 V. The LiCoO2-Li button half-cell prepared therefrom had a specific capacity of 141 mAh·g−1 at a rate of 1C. The coulombic efficiency remained above 99% within 100 cycles and the capacity retention rate reached 99.5%, which reveals an excellent cycling stability.

Na0.25K0.25Bi0.5TiO3 (NKBT) perovskite particles are synthesized by solid-state method and used as a filler for polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) co-polymer. X-ray diffraction analysis of NKBT powders shows that the particles have a rhombohedral perovskite crystal structure (R3c symmetry). Raman spectroscopy reveals that the co-polymer crystallizes predominantly into the mixture of polar β- and γ-crystals, while there is also a contribution of the non-polar α-crystal phase. The introduction of the NKBT into the PVDF-HFP results with an increase in effective dielectric permittivity and this effect depends on the inorganic content in the composite. The most interesting result of the present study is that the introduction of NKBT particles induces the appearance of an additional transition peak in the dielectric spectra of the co-polymer matrix. At the fixed frequency of ~2 kHz, the observed process appears at ~10 °C (about 45° above the glass transition temperature) and its magnitude strongly depends on the amount of the NKBT in the composite. Dielectric spectroscopy measurements of the composites are carried out in the wide range of frequencies (from 0.1 Hz to 1 MHz) and temperatures (from −100 to 100 °C). They reveal that the novel process can be clearly distinguished in the frequency range between 160 Hz and ~50 kHz. © 2021 The Authors

Textile-based pressure sensors have garnered considerable interest in electronic textiles due to their diverse applications, including human–machine interface and healthcare monitoring systems. We studied a textile-based capacitive pressure sensor array using a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/ionic liquid (IL) composite film. By constructing a capacitor structure with Ag-plated conductive fiber electrodes that are embedded in fabrics, a capacitive pressure sensor showing high sensitivity, good operation stability, and a wide sensing range could be created. By optimizing the PVDF-HFP:IL ratio (6.5:3.5), the fabricated textile pressure sensors showed sensitivity of 9.51 kPa−1 and 0.69 kPa−1 in the pressure ranges of 0–20 kPa and 20–100 kPa, respectively. The pressure-dependent capacitance variation in our device was explained based on the change in the contact-area formed between the multi-filament fiber electrodes and the PVDF-HFP/IL film. To demonstrate the applicability and scalability of the sensor device, a 3 × 3 pressure sensor array was fabricated. Due to its matrix-type array structure and capacitive sensing mechanism, multi-point detection was possible, and the different positions and the weights of the objects could be identified.

Lithium-air batteries (LABs) continue to receive attention as a promising power source because they possess a high theoretical energy density of 3436 Wh L&minus, 1. However, the remaining Li2O2 resulting from the irreversible decomposition of Li2O2 during the charge process is one of the key challenges so as to address the deterioration of the cycling performance of LABs. In this study, we propose and report a redox-mediated polymer catalyst (RPC) as a cathode catalyst being composed of LiI and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with multi-wall carbon nanotubes (MWCNTs) as the cathode material. In the RPC, iodine molecules are chemically combined with the PVDF-HFP chain. The as-prepared RPC exhibits increased cycling performance by 194% and decreased overpotential by 21.1% at 0.1 mA cm&minus, 2 compared to the sample without LiI molecules. Furthermore, these results suggest that the RPC consisting of a polymer chain and redox mediators will be extensively utilized as highly efficient catalysts of LABs.

Chemical pollutants, such as methyl orange (MO), constitute the main ingredients in the textile industry wastewater, and specifically, the dyeing process. The use of such chemicals leads to huge quantities of unfixed dyes to make their way to the water effluent and consequently escalates the water pollution problem. This work investigates the incorporation of hydrophobic carbon nanospheres (CNS) prepared from the pyrolysis of acetylene using the chemical vapor deposition technique with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in order to enhance its hydrophobicity. Moreover, a deep eutectic solvent (DES) was used to enhance the membrane’s porosity. The former was based on the quaternary ammonium salt (N,N-diethyl-ethanol-ammonium chloride) as a chemical addition throughout the membrane synthesis. Direct contact membrane distillation (DCMD) was employed to assess the performance of the modified membrane for treatment of MO contaminated water. The phase inversion method was used to embed various contents of CNS (i.e., 1.0, 3.0, and 5.0 wt.%) with 22:78 wt.% of PVDF-co-HFP/N-Methyl-2-pyrrolidone solution to prepare flat-sheet membranes. The membrane embedded with 5 wt.% CNS resulted in an increase in membrane hydrophobicity and presented considerable enhancement in DCMD permeation from 12 to 35 L/h.m2 with salt rejection >99.9%. Moreover, the composite membrane showed excellent anti-biofouling and mechanical characteristics as compared to the pristine counterpart. Using this membrane, a complete rejection of MO was achieved due to the synergistic contribution of the dye negative charge and the size exclusion effect.

Submitted by Guilherme Dognani (dognani.g@gmail.com) on 2020-10-27T18:37:20Z No. of bitstreams: 1 Dognani, G _2020_TeseDeDoutorado.pdf: 5383570 bytes, checksum: 8951fe090eeeb437a21b05e3f2947110 (MD5) Approved for entry into archive by ALESSANDRA KUBA OSHIRO ASSUNÇÃO (alessandra@fct.unesp.br) on 2020-10-27T20:42:37Z (GMT) No. of bitstreams: 1 dognani_g_dr_prud.pdf: 5383570 bytes, checksum: 8951fe090eeeb437a21b05e3f2947110 (MD5) Made available in DSpace on 2020-10-27T20:42:37Z (GMT). No. of bitstreams: 1 dognani_g_dr_prud.pdf: 5383570 bytes, checksum: 8951fe090eeeb437a21b05e3f2947110 (MD5) Previous issue date: 2020-09-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) O consumo mundial de água tem aumentado em cerca de 1% ao ano desde a década de 1980 devido à combinação do rápido crescimento populacional, do desenvolvimento socioeconômico e das mudanças nos padrões de consumo da população mundial. Hoje, cerca de 2 bilhões de pessoas vivem em países que sofrem alto estresse hídrico sem o acesso a água limpa, devido aos altos índices de poluição. Assim, a crise atual deixa de ser apenas relacionada à quantidade disponível e passa a ocupar patamares alarmantes em relação à qualidade da água consumida. Neste sentido, novos materiais estão sendo desenvolvidos afim de descontaminar/remediar fontes de água com diferentes tipos de contaminantes. Neste trabalho, foram produzidas membranas porosas de PVDF-HFP por meio de eletrofiação, estudando a variação de parâmetros e a relação do tempo na densidade de fibras e então testes de adsorção foram realizados. Inicialmente o estudo dos parâmetros foi realizado a fim de produzir materiais com propriedades para aplicação em membranas de destilação, filtração e adsorção. As membranas eletrofiadas foram recobertas com polianilina (PAni) por meio da polimerização in situ em sua superfície a fim de criar uma membrana com capacidade de remoção de íons cromato de meios aquosos. A morfologia e estrutura das membranas foram avaliadas antes e após o recobrimento da superfície com polianilina; os resultados mostram o sucesso do processo de polimerização in situ na deposição de moléculas de PAni nas nanofibras de PVDF-HFP. As membranas de alta porosidade e área superficial foram então testadas quanto sua capacidade de remoção de íons cromato e dicromato de meio aquoso em altas e baixas concentrações. Os testes de adsorção estática mostraram a eficiência na remoção dos íons metálicos, encontrando uma capacidade de adsorção de aproximadamente 15 mg/g; a capacidade de remoção foi também avaliada em função do valor do pH e do tempo de adsorção. Testes dinâmicos de adsorção em diferentes vazões e volumes de solução de cromo foram também realizados. O estudo de dessorção confirmou ainda a reciclabilidade da membrana PVDF-HFP/PAni, mostrando uma eficiência superior a 70%, mesmo após 5 ciclos de utilização. Quando testado em baixas concentrações, que buscam simular efluentes industriais descartados em córregos e rios, a membrana PVDF-HFP/PAni teve uma eficiência de remoção de espécies de Cr(VI) acima de 80% quando em concentrações de até 0,3 mg/L. Para estas baixas concentrações do contaminante o processo de adsorção ocorreu de forma espontânea e exotérmica. Por fim a eficiência das membranas foi avaliada por meio de teste de viabilidade celular para células de peixe expostas à solução de Cr(VI) após o processo de adsorção, aumentando em torno de 19% a viabilidade de células. Diante das caracterizações realizadas e dos estudos de adsorção, dessorção e viabilidade celular, conclui-se que a membrana desenvolvida neste trabalho se mostra como um material de potencial aplicação em descontaminação de águas, adsorvendo espécies aniônicas de cromo presente em meio aquoso, promovendo um ambiente aquático mais seguro para espécies que vivem ou utilizam de alguma forma estas águas. The world water consumption has been increasing about 1% per year since the 1980s due to the combination of rapid population growth, socioeconomic development and changes in the consumption patterns of the world population. Nowadays, about 2 billion people live in countries that suffer from high water stress without access to clean water, due to high levels of pollution. Thus, the current crisis is no longer just related to the quantity available and starts to occupy alarming levels in relation to the quality of the water consumed. In this sense, new materials are being developed in order to decontaminate/remediate water sources with different types of contaminants. In this study, porous membranes of PVDF-HFP were produced by electrospinning; the production parameters and the fibers density relationship were studied, then the adsorption tests were carried out. Initially the study of parameters was carried out in order to produce materials with properties to apply in distillation, filtration and adsorption membranes. The electrospun membranes were coated with polyaniline (PAni) by in situ polymerization in order to create a membrane capable of removing chromate ions from aqueous media. The morphology and structure of the membranes were evaluated before and after the polyaniline-coated surface, the results show the success of in situ polymerization process to deposit the PAni molecules in the PVDF-HFP nanofibers. The high porosity and surface area membranes were then tested for their ability to remove chromate and dichromate ions from aqueous medium in high and low concentrations. The static adsorption tests showed the efficiency in metal ions removal, finding an adsorption capacity of approximately 15 mg/g; the removal capacity was also evaluated according to the pH value and the contact time. Dynamic adsorption tests at different flows rate and volumes of chromium solutions were also performed. The desorption study confirmed the recyclability of the PVDF-HFP/PAni membrane, showing an efficiency over 70%, even after 5 cycles of use. When tested in low concentrations, which aim simulate an industrial effluents released in streams and rivers, the PVDF-HFP/PAni membrane had an efficiency of removing Cr(VI) species over 80% when in concentrations over to 0.3 mg/L of Cr(VI). For these low concentrations of contaminant, the adsorption process occurred spontaneously and by exotherm process. Finally, the membrane efficiency was evaluated through cell viability test on fish cells exposed to the Cr(VI) solution after the adsorption process, the cell viability increased about 19%. Given the characterizations carried out and the studies of adsorption, desorption and cell viability, it is concluded that the membrane developed in this work shows itself as a material of potential application in water decontamination, adsorbing anionic species of chromium present in aqueous medium, promoting an environment safer aquatic environment for species that live or use these waters in some way. According the characterizations and the studies of adsorption, desorption and cell viability, it is concluded that the membrane developed in this work proved to be a material with potential application in water decontamination, adsorbing anionic species of chromium present in aqueous medium, and promoting an safer aquatic environment for species that live or use these waters in some way. FAPESP: 2015/21261-2 FAPESP: 2017/03638-7

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O2) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li+ distribution. To tackle this complex dilemma, here, an HSE with rigid Li1.5Al0.5Ge1.5(PO4)3 (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li+ diffusion network to homogenize Li+ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li+ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O2 battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O2 battery. This new insight may serve as a starting point for further designing of HSE in Li-O2 batteries, and can also be extended to various battery systems such as sodium-oxygen batteries., Hybrid solid electrolyte with rigid core@ultrathin flexible shell interface suppresses Li dendrite formation effectively, enabling high-performance quasi-solid-state lithium-oxygen batteries.

Composite materials based on ionic liquids (ILs) / poly(vinylidene fluoride) (PVDF) and their copolymers have emerged as an interesting approach to develop high ionic conductivity solid polymer electrolytes (SPEs) for lithium-ion battery application. This work reports the development of SPEs based on fluoropolymers, PVDF and poly(vinylidene fluoride co-hexafluoropropylene), PVDF-HFP, containing different ILs: 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([EMIM][TFSI]) and 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]). The influence of IL type and content on the morphological, wettability, physical-chemical, thermal, mechanical and electrochemical properties were evaluated. It is shown that, independently of the polymer matrix, both ILs improve surface wettability and increase the polar β phase content and crystallinity degree of the polymers. The mechanical properties show that the incorporation of IL in the composites results in a plasticizing behaviour. Further, the [BMIM][SCN]/PVDF-HFP with 40 wt.% IL content shows the best room temperature ionic conductivity of 0.15 mS.cm-1 with excellent electrochemical stability in the 0.0 - 5.0 V potential window. The initial discharge capacity value at C/8-rate is 148 mAh.g-1 and 124 mAh.g-1 for the [BMIM][SCN]/PVDF and [BMIM][SCN]/PVDF-HFP composites, respectively, with high coulombic efficiency (98%). At C/8-rate, batteries with [BMIM][SCN]/PVDF-HFP show the lowest capacity fade (16 % after 50 cycles) of the prepared composites. Thus, it is demonstrated the suitability of developing SPEs based on IL and fluorinated polymers for the next generation of solid-state room temperature lithium-ion batteries., Work supported by the Portuguese Foundation for Science and Technology (FCT) undes strategic funding UID/FIS/04650/2020 and UID/QUI/0686/2020, project PTDC/FISMAC/28157/2017, and Grants SFRH/BD/140842/2018 (J.C.B.), SFRH/BPD/121526/2016 (D.M.C), CEECIND/00833/2017 (R.G.) and SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.

In this work, electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber membranes were loaded with tungsten oxide (WO3) nanoparticles, surface coated with polydopamine (PDA) hierarchical structures, and tested in oil/water separation, photothermal water evaporation, and degradation of ampicillin. The electrospun nanofiber membranes (ENMs) consisted of three layers and the WO3 nanoparticles were incorporated into the top layer to increase their surface exposure. These layers were then heat-pressed for dimensional stability and surface coated with PDA hierarchical structures. Characterization was conducted using microscopic, goniometric, gravimetric, and spectroscopic methods. All ENMs displayed randomly oriented, smooth microporous structure and EDS mapping revealed a uniform distribution of WO3 nanoparticles on the nanofiber matrix. WO3-blended ENMs showed improved mechanical strength, higher UV/Vis absorption, and similar thickness as pristine ENM. PDA deposition has reduced the water contact angle of pristine PVDF-HFP membrane from 130.3 to 0°, whereas, the underwater oil contact angle has increased from 55.8 to 159.7°. The PDA-coated ENMs exhibited enhanced oil/water separation with 384.3 L m−2h−1 (LMH) of flux and 97.6% oil rejection when filtered under gravity. Photothermal interfacial evaporation and ampicillin degradation tests also demonstrated the multifunctionality and exciting features of the fabricated membranes for a wide range of applications.

In this work, the comparison between PVDF-HFP porous structures loaded with 3% w/w curcumin (Cm), produced by supercritical assisted processes, was performed. In the case of membranes, different operative conditions (from 250 bar/35 °C to 150 bar/55 °C) and polymer concentrations (from 10 to 30% w/w) were tested. A cellular membranes morphology was observed and porosity values up to 89% were measured. Cm release was prolonged from 20 h to 26 h changing the PVDF-HFP membrane concentration from 20 to 30% w/w. PVDF-HFP-Cm aerogels were produced by supercritical drying, operating at 200 bar and 45 °C. A nanofibrous aerogels morphology was obtained with open and interconnected pores, reaching porosity values of 94%. The maximum Cm release was prolonged up to 44 h for 12% w/w PVDF-HFP aerogel. Kosmeyers-Peppas model produced a fair good representation of the Cm release experimental results for PVDF-HFP-Cm membranes and aerogels.

Lithium metal batteries (LMBs) show several limitations, such as high flammability and Li dendrite growth. All‐solid‐state LMBs (ASSLMBs) are promising alternatives to conventional liquid electrolyte (LE)‐based LMBs. However, it is challenging to prepare a solid electrolyte with both high ionic conductivity and low electrode–electrolyte interfacial resistance. In this study, to overcome these problems, a solid composite electrolyte (SCE) consisting of Li6.25La3Zr2Al0.25O12 and polyvinylidene fluoride‐co‐hexafluoropropylene is used, which has attracted considerable attention in recent years as a solid‐state electrolyte. To operate LMBs without an LE, optimization of the electrode–solid‐electrolyte interface is crucial. To achieve this, physical and chemical treatments are performed, i.e., direct growth of each layer by drop casting and thermal evaporation, and plasma treatment before the Li evaporation process, respectively. The optimized ASSLMB (amorphous V2O5− x (1 µm)/SCE (30 µm)/Li film (10 µm)) has a high discharge capacity of 136.13 mAh g−1 (at 50 °C and 5 C), which is 90% of that of an LMB with an LE. It also shows good cycling performance (>99%) over 1000 cycles. Thus, the proposed design minimizes the electrode–solid‐electrolyte interfacial resistance, and is expected to be suitable for integration with existing commercial processes., The electrochemical properties of all‐solid‐state lithium metal batteries (ASSLMBs) are significantly improved through a novel combined fabrication method that involves physical and chemical processing steps. The optimized ASSLMB cell (amorphous V2O5− x (a‐V2O5‐X)/solid composite electrolyte (SCE)/Li film) exhibits a high discharge capacity, which is 90% of that of a liquid‐based cell. It also demonstrates excellent cycling performance over 1000 cycles.

Summary We investigate the effects of thermally sensitive binder (TSB) on the temperature increase of lithium-ion battery (LIB) coin cell subjected to severe mechanical abuse. The TSB is poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP), similar to conventional poly(vinylidenefluoride) (PVDF) binder but with a significant hexafluoropropylene (HFP) content. The testing data show that by using TSB, the peak temperature increase of nail-penetrated LIB coin cell can be reduced by 20% to 40%, attributed to the softening of TSB that begins from ~80°C. The cycling performance of the LIB cells is also characterized. This research sheds light on the development of thermal-runaway mitigation techniques.

To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 &times, 10 &minus, 3 S cm&minus, 1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g&minus, 1 at 110 &deg, C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments.

To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 × 10 −3 S cm−1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g−1 at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments.

Bu tez çalışması Pamukkale Üniversitesi Bilimsel Araştırma Projesi tarafından 2018FEBE021 nolu proje ile desteklenmiştir. Bu çalışmada Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDFHFP) malzemesinin seramik ve mermer yüzeylere kaplanarak, yüzey temas açılarındaki değişimler gözlenmiştir. Başlangıç maddesi olarak PVDF-HFP malzemesi, aseton (C3H6O) ile belirli oranlarda karıştırılarak solüsyon haline getirilmiş, belirli sıcaklık ve sürelerde ısıl işleme tabi tutularak yüzey temas açıları belirlenmiştir. Aynı zamanda seramik yüzeylerin mekanik dayanıklılığını artırmak için kullanılan sır tozuna eklenen PVDF-HFP ve C3H6O, süspansiyon halinde yüzeye kaplanarak ısıl işleme tabi tutulmuş ve temas açıları deneysel olarak hesaplanmıştır. Kaplama uygulanan deney numunelerinde temas açısı 104,88o mertebelerinde gözlemlenerek, seramik yüzeylerin temizliğinde kullanılan kimyasal maddelerin kullanımında azalma hedeflenmiştir. Sonuç olarak deneysel yöntemlerle kütlece yüzde bileşimlerin temas açısında etkisi incelenmiş ve en verimli sonuç 104,88o ile yüzeye direkt PVDF-HFP uygulaması metodunda gözlenmiştir. In this study, Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) material was coated on ceramic and marble surfaces and changes in surface contact angles were observed. As the starting material, PVDF-HFP material was mixed with acetone (C3H6O) in certain proportions and then subjected to heat treatment at certain temperatures and times to determine surface contact angles. At the same time, PVDF-HFP and C3H6O added to the glaze powder used to increase the mechanical strength of the ceramic surfaces were coated on the surface in suspension and heat treated and contact angles were calculated experimentally. The contact angle of the test specimens was observed at 104.88o and the reduction of the usage of chemical materials used in cleaning ceramic surfaces was aimed. As a result, the effect of percentages on the contact angle was investigated by experimental methods and the most efficient result was observed with direct application of PVDF-HFP to the surface with 104,88o.

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride&ndash, hexafluoropropylene (PVDF&ndash, HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF&ndash, HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF&ndash, HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-&alpha, tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF&ndash, HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain&ndash, stress experiments. Finally, ionic conductivity has been studied in the &minus, 50 to 90 &deg, C temperature range and in diffusivity at 25 &deg, C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS&middot, cm&minus, 1 at 25 &deg, C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI.

Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) and polyvinylidene fluoride (PVDF) blend membranes, with interconnected channels decorated with polymer crystallites, were produced by a two-step phase separation technique, using non-toxic solvents and without any chemical additive as pore forming. Results demonstrated that the mass-transport and the interface properties of the membranes can be tailored by a synergic combination of immiscible blend components and an adequate manufacturing procedure, that exploit the slow diffusion of the non-solvent by vapor induced phase separation. In this way, multi-level hierarchical surfaces, with raspberry- and cauliflower-like substructures, were obtained. The optimal blending ratio between the two components was assessed by chemical physical and mass-transport properties characterizations of the prepared membranes. The beneficial effect of blending was evidenced for all the properties investigated (crystallinity, surface roughness, wettability, surface charge, strength, toughness and flux), indicating a good physical interaction between the two components, despite their thermodynamically stated immiscibility. This physical interaction was also proved by the presence of PVDF crystallites embedded in the PVDF-HFP network of blend membranes, which act as reinforcing agents rather than as independent fillers with respect to the pure co-polymer, providing enhanced mechanical properties.

[EN] The increasing use of electronic portable systems and the consequent energy demand, leads to the need to improve energy storage systems. According to that and due to safety issues, high-performance non-flammable electrolytes and solid polymer electrolytes (SPE) are needed. SPE containing different amounts of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) into a poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, polymer matrix have been prepared by solvent casting. The addition of LiTFSI into PVDF-HFP allows to tailor thermal, mechanical and electrical properties of the composite. In particular, the ionic conductivity of the composites increases with LiTFSI content, the best ionic conductivities of 0.0011 mS/cmat 25 degrees C and 0.23 mS/cmat 90 degrees C were obtained for the PVDF-HFP/LiTFSI composites with 80 wt % of LiTFSI. This solid electrolyte allows the fabrication of Li metallic/SPE/C-LiFePO4 half-cells with a discharge capacity of 51.2 mAh/ g at C/20. Further, theoretical simulations show that the discharge capacity value depends on the lithium concentration and percentage of free ions and is independent of the solid polymer electrolyte thickness. On the other hand, the voltage plateau depends on the SPE thickness. Thus, a solid electrolyte is presented for the next generation of safer solid-state batteries., The authors thank the FCT (Fundacao para a Ciencia e Tecnologia) for financial support under the framework of Strategic Funding grants UID/FIS/04650/2013, UID/EEA/04436/2013 and UID/QUI/0686/2016; and project no. PTDC/FIS-MAC/28157/2017. The authors also thank the FCT for financial support under grant SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged. JMMD and JLGR acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-1 and 3-R (including the FEDER financial support) CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance fromthe European Regional Development Fund.

A new-fangled nonaflate anion based ionic liquid ternary gel polymer electrolytes was prepared and their function as an active separator for lithium ion battery applications has been characterized. The ionic liquid gel polymer electrolytes (IGPEs) were prepared using facile solution cast technique by incorporating electrolyte mixtures such as lithium nonafluorobutanesulfonate (LiNfO) and 1-butyl-3-methylimidazolium nonafluorobutanesulfonate (BMImNfO) in poly vinylidenefluoride-co-hexafluoropropylene (PVdF-co-HFP) matrix. The electrochemical performance and the interactions between PVdF-co-HFP, LiNfO and imidazolium-based ionic liquid BMImNfO are comparatively investigated. IGPEs obey Arrhenius relation and its ionic conductivity is found to be maximum of 10(-2) S cm(-1) at 100 degrees C. At low current rate, IGPE also exhibits good cycling performance with LiCoO2 and achieved a maximum discharge capacity of 138.1 mA h g(-1). (C) 2016 Elsevier B.V. All rights reserved.

Formation of single fibres of polymer nanocomposite PVDF-HFP containing MWCNT by Pyro-EHD electrospinning is reported for the first time. Pyro-EHD gives the chance to drawing fibres directly from a viscous polymeric solution containing MWCNT, with respect to classical electrospinning in which highly viscous materials have strong limitation due to the clogging effect. This method allows achieving an electrical conductivity of the fibres considerably higher with respect to the bulk state. The improvement of the electrical conductivity is of one order of magnitude and the electrical percolation threshold is reduced from 2.5 to 0.3 wt%. We also show that the MWCNT are highly oriented in the longitudinal direction of the fibres, producing the improvement in the electrical properties of the composite.

Presentada en NALS 2017 Conference on Nanomaterials applied to Lifesciences in Gijón, Spain, 13-15 December 2017 The development of polymer membranes with tailored micro-morphology and wettability are a demand in the areas of filtration, sensors or tissue engineering, among others. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is a thermoplastic copolymer and one of the most interesting polymers to be used in these areas due to its good mechanical and thermal properties, biocompatibility and low density. The control of the morphology on this material is crucial for its performance [1]. However, for the moment this is a complicated task and is mostly restricted to the use of solvent evaporation (SE) and non-solvent-induced phase separation (NIPS) techniques. In this way, this work consists in a systematic study of the use of ionic liquids in the control of these membranes properties. Ionic liquids are molten salts with melting points lower than 100 °C, which stand out for their good properties, such as high good thermal stability, low vapor pressure, nonflammability and their ability to act as solvents of various materials and they have already been studied for the control of morphology in certain materials [2-3]. In this work, the production and the characterization of PVDF-HFP@ionic liquid composite membranes using different ionic liquids (Diethylmethylammonium trifluoromethanesulfonate, 1-Methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-Methylimidazolium chloride) and methodologies (solvent evaporation temperature) are described in detail. The results demonstrate how aspects such as morphology, wettability or mechanical properties change depending on the production methodology employed and on the type of used ionic liquid. In view of the results, it is concluded that the morphology of a polymer composite can be tuned by use ILs and this control of the morphology could open up new possibilities for their use in different applications.

Composite membranes consisting of N-ethyl-N-methylpyrrolidinium fluoro-hydrogenate (EMPyr(FH)1.7F) ionic liquid and poly(vinylidene fluoride hexafluoro-propylene) (PVdF-HFP) copolymer were successfully prepared in weight ratios of 5:5, 6:4, and 7:3 using a casting method. The prepared membranes possessed rough surfaces, which potentially enlarged the three-phase boundary area. The EMPyr(FH)1.7F/PVdF-HFP (7:3 weight ratio) composite membrane had an ionic conductivity of 41 mS·cm-1 at 120 °C. For a single cell using this membrane, a maximum power density of 103 mW·cm-2 was observed at 50 °C under non-humidified conditions, this is the highest power output that has ever been reported for fluorohydrogenate fuel cells. However, the cell performance decreased at 80 °C, which was explained by penetration of the softened composite membrane into gas diffusion electrodes to partially plug gas channels in the gas diffusion layers, this was verified by in situ a.c. impedance analysis and cross-sectional SEM images of the membrane electrode assembly.

Composite membranes consisting of N -ethyl- N -methylpyrrolidinium fluoro-hydrogenate (EMPyr(FH) 1.7 F) ionic liquid and poly(vinylidene fluoride hexafluoro-propylene) (PVdF-HFP) copolymer were successfully prepared in weight ratios of 5:5, 6:4, and 7:3 using a casting method. The prepared membranes possessed rough surfaces, which potentially enlarged the three-phase boundary area. The EMPyr(FH) 1.7 F/PVdF-HFP (7:3 weight ratio) composite membrane had an ionic conductivity of 41 mS·cm -1 at 120 °C. For a single cell using this membrane, a maximum power density of 103 mW·cm -2 was observed at 50 °C under non-humidified conditions; this is the highest power output that has ever been reported for fluorohydrogenate fuel cells. However, the cell performance decreased at 80 °C, which was explained by penetration of the softened composite membrane into gas diffusion electrodes to partially plug gas channels in the gas diffusion layers; this was verified by in situ a.c. impedance analysis and cross-sectional SEM images of the membrane electrode assembly.

In this study, micron-sized pored membranes, based on the co-polymer polyvinylidene difluoride hexafluoropropylene (PVdF-HFP) were prepared via phase inversion techniques. The aim of the approach was to find less harmful and less toxic solvents to fabricate such films. Therefore, the Hansen solubility approach was used to identify safer and less toxic organic solvents for the phase inversion process, relative to present solvent mixtures, based on acetone, dimethyl formamide, dimethyl acetamide or methanol. With this approach, it was possible to identify cyclopentanone, ethylene glycol and benzyl alcohol as suitable solvents for the membrane preparation process. Physicochemical and mechanical properties were analyzed and compared, which revealed a uniform membrane structure through the cross section. Differences were observed at the top surface, in dependence of both preparation approaches, which are described in detail.

Composite membranes were successfully prepared using a phase-inversion method. The X-ray powder diffraction (XRD) and energy dispersive X-ray (EDX) profiles has confirmed formation of 4.8 wt % Ag/poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP), 3 wt % Ag-MWCNTs/PVDF-HFP (EDX surface composition of Ag nanoparticles) and 1.5 wt % MWCNTs/PVDF-HFP composite membranes. The MWCNTs crystallites are mainly encapsulated by a layer of PVDF-HFP, as evidenced by disappearance of graphitic peak. The scanning electron microscopy (SEM) images have depicted the formation of microporous structure, with few MWCNTs on the surface and strongly interacting with PVDF-HFP as demonstrated by thermogravimetric analysis (TGA), XRD and Fourier transform infrared (FTIR) data. The data indicated an increase in porosity, swellability and water content of the PVDF-HFP membrane with the addition of MWCNTs and/or Ag nanoparticles, showing an improved hydrophilicity. The 1.5 wt % MWCNTs/PVDF-HFP composite membrane showed good desalination and fouling resistance rates, which correlates with a low water contact angle. The combined effects of Ag nanoparticles and MWCNTs do not promote fouling resistance of PVDF-HFP membranes, as shown during NaCl microfiltration (this is linked with high water contact angle as compared to that of MWCNTs/PVDF-HFP composite). Both 1.5 wt % MWCNTs/PVDF-HFP and 3 wt % Ag-MWCNTs/PVDF-HFP composite membranes prevented the bacteria passing through the membrane (100% bacterial load reduction). The surface of 3 wt % Ag-MWCNTs/PVDF-HFP showed good bactericidal and non-leaching properties of the dopant materials (MWCNTs and Ag), as evidenced by bacterial growth on the edges of the membranes.

In this work, a new consistent mathematical model for the description of the olefin flux through Ag+-containing polymeric dense membranes is proposed. A fixed site carrier "hopping" parameter acting as an effective permeability for this specific transport phenomenon is defined and calculated for the first time. This study reports a simple and versatile approach that can be incorporated into future models to simulate the more complex mobile/fixed hybrid mechanism acting in composite membranes. Furthermore, in order to validate the model, the proof of concept has been carried out with PVDF-HFP/AgBF4 facilitated transport membranes. The experimental analysis has been performed by the continuous flow permeation method through flat membranes containing increasing silver loads, from 17 to 38% w/w at olefin partial pressures ranging from 0.5 to 1.5 bar and temperatures of 293 and 303 K. These membranes showed a promising performance, reaching values of propylene permeability up to 1800 Barrer and very high propylene/propane selectivities. The reported model constitutes a very useful tool for process optimisation and scale-up. Financial support from the Spanish Ministry of Science under the projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship.

Ionic liquids (IL), liquid salts at room temperature are being explored in different applications due to their good properties such as high chemical and thermal stability, high ion conductivity or non volatility. IL can be combined with a wide variety of polymers for the production of solid membranes which combine the good mechanical properties of the polymeric materials with the properties of the ionic liquids previously mentioned. One of the most interesting applications of these composites is the development of proton exchange membranes (PEM) with high proton conductivity in dry and wet states, good mechanical strength and thermal stability. This work focuses on the development of polymer@ionic liquid membranes using different types of ionic liquids. In particular, the study was focused on the use of PVDF-HFP and three different protic ionic liquids (Diethylmethylammonium trifluoromethanesulfonate, 1-Methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-Methylimidazolium chloride). The membranes were synthesized under different conditions and posteriorly characterized by several techniques (SEM, contact angle, mechanical tests, TGA, FTIR and electrical measurements) in order to compare the properties of the membranes with the different ionic liquids and select the most appropriate for specific applications. From the results, it has been observed how aspects such as morphology, hydrophobicity, conductivity or mechanical properties change depending on the synthesis procedure employed and on the type and amount of ionic liquid used. RESUMEN: Los líquidos iónicos (IL), sales líquidas a temperatura ambiente, son de gran importancia en diferentes aplicaciones debido a las buenas propiedades que poseen, como su alta estabilidad química y térmica, su alta conductividad iónica o su nula volatilidad. Estos materiales se pueden combinar con una gran variedad de polímeros para producir membranas sólidas que combinen las buenas propiedades mecánicas de los materiales poliméricos con las propiedades de los líquidos iónicos. Una de las aplicaciones de interés de estos composites es el desarrollo de membranas de intercambio protónico (PEM), las cuales presentan alta conductividad protónica, buena resistencia mecánica y alta estabilidad térmica. Este trabajo se centra en el desarrollo de composites polímero@líquido iónico, utilizando distintos líquidos iónicos. En particular, se ha utilizado el polímero PVDF-HFP y tres líquidos iónicos próticos diferentes (Diethylmethylammonium trifluoromethanesulfonate, 1-Methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-Methylimidazolium chloride). Las membranas se han sintetizado en diferentes condiciones y, posteriormente, han sido caracterizadas por diversas técnicas (SEM, ángulo de contacto, ensayos mecánicos, TGA, FTIR y medidas eléctricas) con el fin de comparar las propiedades y seleccionar las más apropiadas para determinadas aplicaciones. A partir de los resultados logrados se ha podido observar cómo cambian aspectos como la morfología, la hidrofobicidad, la conductividad o las propiedades mecánicas dependiendo del procedimiento de síntesis empleado y del tipo de líquido iónico utilizado. Máster en Nuevos Materiales

Poster presentado en: New Materials for a Better life! 2017 Workshop, 27/10/2017, Facultad de Ciencia y Tecnología, Universidad del País Vasco The development of polymer membranes with tailored micro-morphology and wettability are a demand in the areas of filtration, sensors or tissue engineering, among others. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is a thermoplastic copolymer and one of the most interesting polymers to be used in these areas due to its good mechanical and thermal properties, biocompatibility and low density. The control of the morphology on this material is crucial for its performance. However, for the moment this is a complicated task and is mostly restricted to the use of solvent evaporation (SE) and non-solvent-induced phase separation (NIPS) techniques. In this way, this work consists in a systematic study of the use of ionic liquids in the control of these membranes properties. Ionic liquids are molten salts with melting points lower than 100 °C, which stand out for their good properties, such as high good thermal stability, low vapor pressure, nonflammability and their ability to act as solvents of various materials and they have already been studied for the control of morphology in certain materials. In this work, the production and the characterization of PVDF-HFP@ionic liquid composite membranes using different ionic liquids (Diethylmethylammonium trifluoromethanesulfonate, 1-Methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-Methylimidazolium chloride) and methodologies (solvent evaporation temperature) are described in detail. The results demonstrate how aspects such as morphology, wettability or mechanical properties change depending on the production methodology employed and on the type of used ionic liquid. In view of the results, it is concluded that the morphology of a polymer composite can be tuned by use ILs and this control of the morphology could open up new possibilities for their use in different applications. “Ministerio de Economía, Industria y Competitividad” (MAT2016-76739-R(AEI/FEDER, UE)). “Gobierno Vasco” ( KK-2016/00095-LISOL, program Elkartek).

A quasi-solid-state polymer electrolyte is prepared by incorporating poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) in a propylene carbonate (PC) / 1,2-dimethoxyethane (DME) / 1-methyl-3-propylimidazolium iodide (MPII) liquid electrolyte. The amount of PVdF-HFP in the liquid electrolyte is varied from 0.1 to 0.4 g. Incorporation of 0.1 g of PVdF-HFP decreases the conductivity of the DME/PC/MPII liquid electrolyte from 1.3×10-2 to 5.6×10-3 S cm-1. Conductivity decreases gradually with increasing PVdF-HFP. No-flow “jelly-like” electrolyte samples are obtained for PVdF-HFP ? 0.2 g. The decrease in conductivity is the result of the decrease in ion mobility. Ion mobility was calculated by impedance spectroscopy. The PVdF-HFP quasi-solid-state electrolytes were assembled into dye sensitized solar cells (DSSCs). The performance of the DSSCs was measured under illumination of a 100 mW cm-2 Xenon light source. The DSSC without PVdF-HFP polymer shows an efficiency of 4.88% with short-circuit current density, Jsc of 11.24 mA cm-2, fill factor, FF of 70% and open circuit voltage, Voc of 619 mV. The presence of PVdF-HFP deteriorates the performance of DSSCs, but problems such as electrolyte leakage and volatilization are eliminated. The performance of DSSCs was found to be correlated to the conductivity behaviour of the electrolyte.

Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) flat sheet membranes were prepared for aqueous membrane distillation (MD) applications using triethyl phosphate (TEP) as less-toxic solvent via phase inversion. PVDF-HFP concentrations of 10, 12 and 15 wt.% were investigated and it was observed that different polymer concentrations led to membranes with different surface structure and performance; the use of different coagulation bath compositions played a key role in the membrane fabrication and affected the performance in membrane distillation. The results showed that the permeation decreased sharply when the polymer concentration increased from 12 to 15 wt.%. By adding isopropanol as non-solvent to coagulation medium led to interesting results in terms of permeation. However, the use of lithium chloride to the casting solution had also a positive impact on membrane characteristics in price of retrograde membrane mechanical properties. Particularly interesting was the membrane produced from solution containing the 12 wt.% polymer and coagulated in the isopropanol–water mixture, which gave a DCMD permeation of 16.1 kg h −1 m −2 at feed temperature of 60 °C, and a salt rejection of 99.3%.

Polymer films and membranes of poly(vinylidene fluoride co-hexafluoropropylene), PVDF-HFP, have been prepared by thermally induced phase separation (TIPS), allowing the tuning of microstructure and morphology. The obtained microstructure is explained by the Flory-Huggins theory, depending on polymer concentration and solvent evaporation temperature. The formation of a porous membrane is attributed to a spinodal decomposition of the liquid-liquid phase separation. The effect of the processing conditions on the morphology, degree of porosity, degree of crystallinity and crystalline polymorph, thermal, dielectric and piezoelectric properties of the PVDF-HFP polymer were evaluated. The crystalline phase and degree of crystallinity depend on the processing conditions and further influence the dielectric and piezoelectric response. The piezoelectric coefficient is correlated with the β-phase content and decreases with decreasing polymer concentration in the initial solution at a given evaporation temperature., This work is funded by FEDER funds through the "Programa Operacional Factores de Competitividade - COMPETE" and by national funds from FCT - Fundacao para a Ciencia e a Tecnologia, in the framework of the strategic project Strategic Project PEST-C/FIS/UI607/2011 and PEst-C/QUI/UI0686/2013). The authors also thank funding from Matepro -Optimizing Materials and Processes", ref. NORTE-07-0124-FEDER-000037", co-funded by the "Programa Operacional Regional do Norte" (ON.2 - O Novo Norte), under the "Quadro de Referencia Estrategico Nacional" (QREN), through the "Fundo Europeu de Desenvolvimento Regional" (FEDER), and grants SFRH/BD/66930/2009 (J.N.P.) and SFRH/BD/68499/2010 (C.M.C.). The authors thank Solvay for kindly supplying the high quality materials.

Electrospun membranes are gaining interest for use in membrane distillation (MD) due to their high porosity and interconnected pore structure; however, they are still susceptible to wetting during MD operation because of their relatively low liquid entry pressure (LEP). In this study, post-treatment had been applied to improve the LEP, as well as its permeation and salt rejection efficiency. The post-treatment included two continuous procedures: heat-pressing and annealing. In this study, annealing was applied on the membranes that had been heat-pressed. It was found that annealing improved the MD performance as the average flux reached 35 L/m2·h or LMH (>10% improvement of the ones without annealing) while still maintaining 99.99% salt rejection. Further tests on LEP, contact angle, and pore size distribution explain the improvement due to annealing well. Fourier transform infrared spectroscopy and X-ray diffraction analyses of the membranes showed that there was an increase in the crystallinity of the polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) membrane; also, peaks indicating the α phase of polyvinylidene fluoride (PVDF) became noticeable after annealing, indicating some β and amorphous states of polymer were converted into the α phase. The changes were favorable for membrane distillation as the non-polar α phase of PVDF reduces the dipolar attraction force between the membrane and water molecules, and the increase in crystallinity would result in higher thermal stability. The present results indicate the positive effect of the heat-press followed by an annealing post-treatment on the membrane characteristics and MD performance.

Escuela Técnica Superior de Ingeniería Industrial Universidad Politécnica de Cartagena