Biodegradable Electrospun Conduit with Aligned Fibers Based on Poly(lactic-co-glycolic Acid) (PLGA)/Carbon Nanotubes and Choline Bitartrate Ionic Liquid

Functionally active aligned fibers are a promising approach to enhance neuro adhesion and guide the extension of neurons for peripheral nerve regeneration. Therefore, the present study developed poly(lactic-co-glycolic acid) (PLGA)-aligned electrospun mats and investigated the synergic effect with carbon nanotubes (CNTs) and Choline Bitartrate ionic liquid (Bio-IL) on PLGA fibers. Morphology, thermal, and mechanical performances were determined as well as the hydrolytic degradation and the cytotoxicity. Results revealed that electrospun mats are composed of highly aligned fibers, and CNTs were aligned and homogeneously distributed into the fibers. Bio-IL changed thermal transition behavior, reduced glass transition temperature (Tg), and favored crystal phase formation. The mechanical properties increased in the presence of CNTs and slightly decreased in the presence of the Bio-IL. The results demonstrated a decrease in the degradation rate in the presence of CNTs, whereas the use of Bio-IL led to an increase in the degradation rate. Cytotoxicity results showed that all the electrospun mats display metabolic activity above 70%, which demonstrates that they are biocompatible. Moreover, superior biocompatibility was observed for the electrospun containing Bio-IL combined with higher amounts of CNTs, showing a high potential to be used in nerve tissue engineering.

Thermodynamics of Tri- and Tetraepoxyimidazolium NTf2 Amine Polyaddition: A Theoretical Perspective

The thermodynamics of newly designed tri- and tetraepoxyimidazolium NTf2 monomers reacting with several diamines used as curing agents to form epoxy/amine thermosets was studied. The ability of each epoxy/amine combination to induce cross-linking both through the substitution of multiple epoxy groups and through multiple additions to a single amine was investigated. Through an increased understanding of the thermodynamics of epoxy-amine polymerization in complex polyepoxy-ILs, it is possible to more thoroughly understand the factors affecting the reactivity in these complex systems. These calculations showed that while each possible epoxy-amine combination was exergonic to both forms of cross-linking, the degree to which both amines-induced cross-linking and epoxy-induced cross-linking was favored varied between epoxy-amine combinations. Thermodynamic results obtained using density functional theory were experimentally validated through differential scanning calorimetry results, wherein similar trends were noted between theory and experiment. Among the trends noted in amines-epoxy combinations tested, tetraepoxyimidazolium NTf2/PACM (i.e., a cycloaliphatic diamine) was found to be a prime candidate for amine cross-linking, with the addition of a second epoxy to a single amine group being notably the most negative of all epoxy-amine combinations at -77.6 kJ mol-1. While in the case of epoxy cross-linking, the aliphatic polyetheramine denoted Jeffamine-D230-containing systems were found to be the most exergonic, with additions of primary amines to triepoxyimidazolium and tetraepoxyimidazolium NTf2 averaging -86.9 kJ mol-1. Interaction energy analysis indicated that the aromatic amine named sulfanilamide is the most favorable to engage in reactions due to having the most negative interaction energies with already highly substituted epoxy monomers. These results can be used to adjust the cross-linking possibilities of tri- and tetraepoxyimidazolium NTf2/amine polymerization and give insight into the predominant cross-linking reactions in these unique systems.

Epoxidized Ionic Liquids as Processing Auxiliaries of Poly(Lactic Acid) Matrix: Influence on the Manufacture, Structural and Physical Properties

In this study, we set out to modify poly(lactic acid) (PLA) by incorporating epoxidized ionic liquids (ILs) that were specifically designed with imidazolium-NTf₂ moieties. First, we synthesized di-, tri- and tetra-epoxidized ILs, which were incorporated into a PLA matrix at 3, 5, and 10 wt% through a melt extrusion process. We investigated the relationship between the structure and properties of the resulting materials in terms of thermal, mechanical, rheological, and surface properties. The results showed the potential of ILs to impact these properties. Notably, the tri- and tetra-epoxidized ILs enhanced the thermal stability of the PLA matrix as well as the crystallinity while reducing the glass transition temperature and melting point, which is promising for reactive extrusion processing. Overall, this research opens new routes for using reactive ILs to improve the processing and properties of PLA polymers.

Inner southern magnetosphere observation of Mercury via SERENA ion sensors in BepiColombo mission

Mercury's southern inner magnetosphere is an unexplored region as it was not observed by earlier space missions. In October 2021, BepiColombo mission has passed through this region during its first Mercury flyby. Here, we describe the observations of SERENA ion sensors nearby and inside Mercury's magnetosphere. An intermittent high-energy signal, possibly due to an interplanetary magnetic flux rope, has been observed downstream Mercury, together with low energy solar wind. Low energy ions, possibly due to satellite outgassing, were detected outside the magnetosphere. The dayside magnetopause and bow-shock crossing were much closer to the planet than expected, signature of a highly eroded magnetosphere. Different ion populations have been observed inside the magnetosphere, like low latitude boundary layer at magnetopause inbound and partial ring current at dawn close to the planet. These observations are important for understanding the weak magnetosphere behavior so close to the Sun, revealing details never reached before.

Rational Design of Solid Polymer Electrolyte Based on Ionic Liquid Monomer for Supercapacitor Applications via Molecular Dynamics Study

The safety concern arising from flammable liquid electrolytes used in batteries and supercapacitors drives technological advances in solid polymer electrolytes (SPEs) in which flammable organic solvents are absent. However, there is always a trade-off between the ionic conductivity and mechanical properties of SPEs due to the lack of interaction between the ionic liquid and polymer resin. The inadequate understanding of SPEs also limits their future exploitation and applications. Herein, we provide a complete approach to develop a new SPE, consisting of a cation (monomer), anion and hardener from ions-monomers using molecular dynamics (MD) simulations. The results show that the strong solid-liquid interactions between the SPE and graphene electrode lead to a very small gap of ∼5.5 Å between the components of SPE and electrode, resulting in a structured solid-to-liquid interface, which can potentially improve energy storage performance. The results also indicated the critical role of the mobility of free-standing anions in the SPE network to achieve high ionic conductivity for applications requiring fast charge/discharge. In addition, the formations of hardener-depleted regions and cation-anion-poor/rich regions near the uncharged/charged electrode surfaces were observed at the molecular level, providing insights for rationally designing the SPEs to overcome the boundaries for further breakthroughs in energy storage technology.

Imidazolium Salt for Enhanced Interfacial Shear Strength in Polyphenylene Sulfide/Ex-PAN Carbon Fiber Composites

Processing structural or semi-structural thermoplastic-based composites is a promising solution to solve the environmental issues of the aeronautic industry. However, these composites must withstand high standard specification to ensure safety during transportation. For this reason, there is a real need to develop strong interactions between thermoplastic polymers and reinforcement fibers. This paper investigates relationships between the surface chemistry, microstructure and micromechanical properties between polyphenylene sulfide and ex-PAN carbon fibers. The incorporation of ionic salt such as 1,3-Bis(4-carboxyphenyl)imidazolium chloride into neat polyphenylene sulfide was able to significantly increase the interfacial shear strength measured by microbond micromechanical test combined with different carbon fiber surfaces treatment.

Sulfonates as Versatile Structural Counterions of Epoxidized Salts

Ionic liquids have recently emerged as monomers to synthesize multifunctional polymeric materials. Among such species, ionic epoxy-based networks represent promising but underdeveloped materials that are hindered by tricky access to the functionalized ionic liquid monomers. To date, the reported epoxidized imidazolium salts have focused on highly toxic epichlorohydrin. This study concerns flexible and efficient methods to synthesize versatile building blocks with sulfonates as valuable anions. The judicious combination of an aliphatic or aromatic sulfonate with an imidazolium leads to new epoxidized salts with high structural variability and good chemical and thermal stability (>300 °C).

Molecular-Level Investigation of Cycloaliphatic Epoxidised Ionic Liquids as a New Generation of Monomers for Versatile Poly(Ionic Liquids)

Recently, a new generation of polymerised ionic liquids with high thermal stability and good mechanical performances has been designed through novel and versatile cycloaliphatic epoxy-functionalised ionic liquids (CEILs). From these first promising results and unexplored chemical structures in terms of final properties of the PILs, a computational approach based on molecular dynamics simulations has been developed to generate polymer models and predict the thermo–mechanical properties (e.g., glass transition temperature and Young’s modulus) of experimentally investigated CEILs for producing multi-functional polymer materials. Here, a completely reproducible and reliable computational protocol is provided to design, test and tune poly(ionic liquids) based on epoxidised ionic liquid monomers for future multi-functional thermoset polymers.

Sulfonimides versus ketosulfonamides as epoxidized imidazolium counterions: towards a new generation of ionic liquid monomers

Ionic liquid monomers with various sulfonimides or ketosulfonamides as unprecedented counteranions of imidazolium ILs were submitted to the Prilezhaev reaction and the intrinsic properties of these new epoxy monomers was unveiled.

Ionic Liquids-Containing Silica Microcapsules: A Potential Tunable Platform for Shaping-Up Epoxy-Based Composite Materials?

In this work, silica microcapsules containing phosphonium ionic liquid (IL), denoted SiO₂@IL, were successfully synthesized for the first time using the one step sol-gel method in IL/H₂0 emulsion. The morphologies of the obtained micron-size microcapsules, including their diameter distribution, were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal behavior of these microcapsules and the mass fraction of the encapsulated IL in the silica microcapsules were determined using thermogravimetric analysis, showing an excellent thermal stability (up to 220 °C) and highlighting that an amount of 20 wt.% of IL is contained in the silica microcapsules. In a second step, SiO₂@IL microcapsules (1 wt.%) were dispersed into epoxy-amine networks to provide proof of concept of the ability of such microcapsules to act as healing agents as microcracks propagate into the epoxy networks.

Cycloaliphatic epoxidized ionic liquids as new versatile monomers for the development of shape memory PIL networks by 3D printing

Efficient synthesis of cycloaliphatic epoxy IL monomers followed by thermal curing to obtain shape-memory hydrophobic PIL networks is reported for the first time.

Nanocellulose/bioactive glass cryogels as scaffolds for bone regeneration

A major challenge exists in the preparation of scaffolds for bone regeneration, namely, achieving simultaneously bioactivity, biocompatibility, mechanical performance and simple manufacturing. Here, cellulose nanofibrils (CNF) are introduced for the preparation of scaffolds taking advantage of their biocompatibility and ability to form strong 3D porous networks from aqueous suspensions. CNF are made bioactive for bone formation through a simple and scalable strategy that achieves highly interconnected 3D networks. The resultant materials optimally combine morphological and mechanical features and facilitate hydroxyapatite formation while releasing essential ions for in vivo bone repair. The porosity and roughness of the scaffolds favor several cell functions while the ions act in the expression of genes associated with cell differentiation. Ion release is found critical to enhance the production of the bone morphogenetic protein 2 (BMP-2) from cells within the fractured area, thus accelerating the in vivo bone repair. Systemic biocompatibility indicates no negative effects on vital organs such as the liver and kidneys. The results pave the way towards a facile preparation of advanced, high performance CNF-based scaffolds for bone tissue engineering.

Ionic Liquid-Nanostructured Poly(Methyl Methacrylate)

Here, ionic liquids (ILs) based on imidazolium and ammonium cations were used as modifying agents for poly(methyl methacrylate) (PMMA) by extrusion. The effects of the chemical nature of the cation and/or counter anion on the resulting properties of IL-modified PMMA blends were analyzed. It was found that the use of low amounts of ILs (2 wt.%) improved the thermal stability. A plasticizing effect of ILs is evidenced by a decrease in glass transition temperature Tg of the modified PMMA, allowing to get large strains at break (i.e., up to 280% or 400%) compared to neat PMMA. The deformation and fracture mechanisms of PMMA under uniaxial tensile stress (i.e., crazing) reveal that the presence of IL delayed the strain during the initiation step of crazing.

Ionic Liquids as Delaminating Agents of Layered Double Hydroxide during In-Situ Synthesis of Poly (Butylene Adipate-co-Terephthalate) Nanocomposites

Currently, highly demanded biodegradable or bio-sourced plastics exhibit inherent drawbacks due to their limited processability and end-use properties (barrier, mechanical, etc.). To overcome all of these shortcomings, the incorporation of lamellar inorganic particles, such as layered double hydroxides (LDH) seems to be appropriate. However, LDH delamination and homogenous dispersion in a polymer matrix without use of harmful solvents, remains a challenging issue, which explains why LDH-based polymer nanocomposites have not been scaled-up yet. In this work, LDH with intercalated ionic liquid (IL) anions were synthesized by a direct co-precipitation method in the presence of phosphonium IL and subsequently used as functional nanofillers for in-situ preparation of poly (butylene adipate-co-terephthalate) (PBAT) nanocomposites. The intercalated IL-anions promoted LDH swelling in monomers and LDH delamination during the course of in-situ polycondensation, which led to the production of PBAT/LDH nanocomposites with intercalated and exfoliated morphology containing well-dispersed LDH nanoplatelets. The prepared nanocomposite films showed improved water vapor permeability and mechanical properties and slightly increased crystallization degree and therefore can be considered excellent candidates for food packaging applications.

A radiation belt of energetic protons located between Saturn and its rings

Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable radiation belts exist near the planet and inward of the rings was previously unknown. The Cassini spacecraft’s Magnetosphere Imaging Instrument obtained measurements of a radiation belt that lies just above Saturn’s dense atmosphere and is decoupled from the rest of the magnetosphere by the planet’s A- to C-rings. The belt extends across the D-ring and comprises protons produced through cosmic ray albedo neutron decay and multiple charge-exchange reactions. These protons are lost to atmospheric neutrals and D-ring dust. Strong proton depletions that map onto features on the D-ring indicate a highly structured and diverse dust environment near Saturn.

Ionic Liquid as Surfactant Agent of Hydrotalcite: Influence on the Final Properties of Polycaprolactone Matrix

This paper reports the surface treatment of layered double hydroxide (LDH) by using ionic liquid (IL) composed of phosphonium cation combined with 2-ethylhexanoate (EHT) counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt %) of thermally stable organically modified LDH (up to 350 °C) denoted LDH-EHT were incorporated into polycaprolactone (PCL) matrix by mechanical milling. The influence of LDH-EHT loading has been investigated on the physical properties, such as the thermal and barrier properties, as well as the morphologies of the resulting nanocomposites. Thus, intercalated or microcomposite morphologies were obtained depending on the LDH-EHT loading, leading to significant reduction of the diffusion coefficient respect to water vapor. The modulation of barrier properties, using low functionalized filler amount, is a very important aspect for materials in packaging applications.

The properties of new epoxy networks swollen with ionic liquids

In this work, ionic liquids based on trihexyl(tetradecyl)phosphonium associated with bis(2,4,4-trimethylpentyl)phosphinate [TMP] and dicyanamide [DCA] counter anions were used as reactive additives within epoxy/amine networks.

Probing nanomechanical properties with AFM to understand the structure and behavior of polymer blends compatibilized with ionic liquids

The PeakForce QNM AFM mode was used to investigate the nanoscale mechanical properties of poly(butylene-adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) blends successfully compatibilized with phosphonium-based ionic liquids (ILs).

Phosphonium ionic liquids as new compatibilizing agents of biopolymer blends composed of poly(butylene-adipate-co-terephtalate)/poly(lactic acid) (PBAT/PLA)

Effect of phosphonium ionic liquids on the morphologies of PBAT/PLA blends.

Ionic liquids–lignin combination: an innovative way to improve mechanical behaviour and water vapour permeability of eco-designed biodegradable polymer blends

In this work, the potential use of lignin combined with ionic liquids (ILs) has been investigated on the final properties of biodegradable polymer blends.

Ionic compatibilization of polypropylene/polyamide 6 blends using an ionic liquids/nanotalc filler combination: morphology, thermal and mechanical properties

In this study, room temperature ionic liquids (RTILs) based on phosphonium cations have been used as effective compatibilizers of polyolefin/polyamide 6/synthetic talc blends using a melt extrusion process.

The SupraThermal Ion Monitor for space weather predictions

Measurement of suprathermal energy ions in the heliosphere has always been challenging because (1) these ions are situated in the energy regime only a few times higher than the solar wind plasma, where intensities are orders of magnitude higher and (2) ion energies are below or close to the threshold of state-of-art solid-state detectors. Suprathermal ions accelerated at coronal mass ejection-driven shocks propagate out ahead of the shocks. These shocks can cause geomagnetic storms in the Earth's magnetosphere that can affect spacecraft and ground-based power and communication systems. An instrument with sufficient sensitivity to measure these ions can be used to predict the arrival of the shocks and provide an advance warning for potentially geo-effective space weather. In this paper, we present a novel energy analyzer concept, the Suprathermal Ion Monitor (STIM) that is designed to measure suprathermal ions with high sensitivity. We show results from a laboratory prototype and demonstrate the feasibility of the concept. A list of key performances is given, as well as a discussion of various possible detectors at the back end. STIM is an ideal candidate for a future space weather monitor in orbit upstream of the near-earth environment, for example, around L1. A scaled-down version is suitable for a CubeSat mission. Such a platform allows proofing the concept and demonstrating its performance in the space environment.

Synthesis and physical properties of new layered silicates based on ionic liquids: improvement of thermal stability, mechanical behaviour and water permeability of PBAT nanocomposites

Ionic liquids based on tetraalkylphosphonium and dialkyl imidazolium cations with long alkyl chains have been investigated as new surfactant agents for cationic exchange of lamellar silicates.

Nanostructured thermosets from ionic liquid building block–epoxy prepolymer mixtures

TEM micrographs of the epoxy–IL cured systems with 30 wt% of phosphonium ionic liquid.

Genetic structure of Barbus spp. populations in the Marches Region of central Italy and its relevance to conservation actions

A genetic survey of Barbus spp. populations in the Marches Region (Adriatic River basins), central Italy, was carried out using mitochondrial and nuclear markers (partial D-loop, cyt b sequences and microsatellite loci) in order to ascertain their systematic position and to address their genetic structure which is key to conservation action planning. Analyses were conducted on sequences obtained from 91 individuals collected from eight sampling sites in five different rivers, from two specimens provided by the Ichthyological Centre of Rome and mitochondrial sequences of Barbus spp. retrieved from GenBank. Presumptive classification based on external morphological characters was not confirmed by genetic analysis, by means of which all specimens collected in the Marches Region were ascribed to Barbus plebejus. Genetic diversity values (h and π) of sampling groups were all different from 0 except the one sample collected from the upper reaches of the River Tenna, above a hydroelectric dam. Population connectivity and colonization patterns of the studied area were inferred from an analysis of molecular variance distribution and evolutionary relationships among haplotypes. The results point to different levels of isolation among sampling groups due to ecological and anthropogenic factors and the effect of an artificial barrier on genetic variability and conservation status of the population. Finally, this study confirms the uncertainty associated with systematic classification of Barbus spp. based on morphological characters due to the phenotypic plasticity of the species.