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We investigate the behavior of small water droplets impacting fabrics of different roughness and coating type in a range of impacting conditions, and compare it to measurements of static and roll-off angles. Fabrics with low roughness display lower static contact angle, no roll-off, a slightly slower retraction rate for impacting droplets, a narrower Weber number (We) range in which rebound occurs, and a limited maximum rebound at intermediate We. Rougher fabrics exhibit slightly higher static contact angles, lower roll-off angles, a slightly faster retraction rate for impacting droplets, and a larger We range for rebound; additionally, the restitution of kinetic energy upon rebound is proportional to 1/We, indicating a near-to-constant rebound height independent of the impact velocity. As regards coating type, roll-off angle, We range for rebound, and to a lesser extent restitution coefficient, depend on coating type, with the more environmentally-friendly wax-based coating being superior to silicone and perfluorobutyl-based ones in both drop impact and roll-off experiments. Our results thus provide hope that perfluorinated coatings can be eliminated in standard textiles, and provide an extensive view of how roughness, coating and impact conditions control the fate of small droplets falling on textiles.

The lack of viability of massive bone allografts for critical-size bone defect treatment remains a challenge in orthopedic surgery. The literature has reviewed the advantages of a multi-combined treatment with the synergy of an osteoconductive extracellular matrix (ECM), osteogenic stem cells, and growth factors (GFs). Questions are still open about the need for ECM components, the influence of the decellularization process on the latter, the related potential loss of function, and the necessity of using pre-differentiated cells. In order to fill in this gap, a bone allograft surrounded by an osteogenic membrane made of a decellularized collagen matrix from human fascia lata and seeded with periosteal mesenchymal stem cells (PMSCs) was analyzed in terms of de-/recellularization, osteogenic properties, PMSC self-differentiation, and angiogenic potential. While the decellularization processes altered the ECM content differently, the main GF content was decreased in soft tissues but relatively increased in hard bone tissues. The spontaneous osteogenic differentiation was necessarily obtained through contact with a mineralized bone matrix. Trying to deepen the knowledge on the complex matrix–cell interplay could further propel these tissue engineering concepts and lead us to provide the biological elements that allow bone integration in vivo.

Multiscale mechanical modelling aims at predicting the failure of composites from the fibre/matrix level up to the component scale. Existing frameworks are limited by the lack of reliable experimental data and by an incomplete understanding of the submicron deformation and failure mechanisms. A novel digital image correlation (DIC) method has been developed for the characterisation of the nanoscale mechanical response in composites, based on latest advances in surface patterning. Indium has been deposited on unidirectional composites leading to a dense, homogeneous speckle with particle diameter around 15 nm. The specimens were subjected to transverse compression in a scanning electron microscope, while minimising distortion effects. Strain concentration areas, like submicron shear bands and fibre–matrix interphases, were successfully captured for two systems: a carbon fibre-reinforced thermoset and a glass fibre-reinforced thermoplastic. DIC results were compared with alternative experimental data, obtained by atomic force microscopy, and with finite element simulations based on a conventional elastoplastic model.

The organic metal-ion battery field remains challenged by the lack of high-voltage alkali-cation reservoir cathode materials. Whereas a few recent breakthroughs provided valuable solutions for Li-ion storage, Na-ion and K-ion organic reservoirs with high voltage and ambient stability remain elusive. Herein, we show that the versatile benzene-1,2,4,5-tetrayltetrakis methylsulfonyl-amide (PTtSA) tetra-anionic framework displays universal performance for alkali cation storage. The new synthesized Na4-PTtSA and K4-PTtSA phases reversibly exchange two Na+ or K+ equivalents per formula unit at redox potentials of 2.5 V vs Na+/Na and 2.6 V vs K+/K, respectively. A singular comparative analysis of Li-, Na-, and K-ion phases discloses the impact of the alkali cation on the physicochemical properties, with direct impact on the electrochemistry of the materials. This work not only offers guidance and principles to tune the redox properties of organic redox materials via spectator cations but also highlights the versatility of organic materials for alkali cation storage.

The commensal skin bacterium Staphylococcus epidermidis provides a range of benefits to human hosts, contributing to skin equilibrium and good health. However, it can also act as a pathogen when entering the host body. Encapsulation is thus considered as a way to maintain the benefits of bacteria and control bacteria dispersion. Among various materials, porous polycarbonate (PC) membranes modified by layer-by-layer (LbL) assembled multilayers attract an increasing interest due to their biocompatible fabrication process and tunable properties. In this thesis, two membrane-based methods have been studied to entrap bacteria. In the first method, a microtube mat is fabricated to encapsulate S. epidermidis. A bicompartmentalized LbL microtube, which contains an erasable external compartment, is designed to release the inner tube without having to dissolve the membrane template in non-biocompatible organic solvents. A hydrogen-bonded poly(N-vinyl caprolactam) (PVCL)/poly(methacrylic acid) (PMAA) system is chosen to build this erasable compartment. We investigate the growth and disaggregation of PVCL/PMAA LbL films, depending on pH, NaCl concentration, and PVCL molar mass. The use of PVCL/PMAA multilayers as a sacrificial compartment is proved to provide an efficient release of nano/micro-structures in biocompatible close-to-neutral aqueous conditions. S. epidermidis can be entrapped in LbL microtube under optimized loading conditions. After tube liberation and collection, the resulting microtube mat is shown to maintain the viability of S. epidermidis. However, the bacterial metabolic activity remains limited. Therefore, a second method of entrapping S. epidermidis in a membrane-in-gel patch is studied. S. epidermidis is loaded in LbL-modified membrane, followed by coating the membrane with a thick layer of agarose gel. The membrane-in-gel maintains the metabolic activity of bacteria. LbL multilayers comprising antibacterial polycations are then deposited over the patch., (FSA - Sciences de l'ingénieur) -- UCL, 2022

The development of biomass pretreatment approaches that, next to (hemi)cellulose valorization, aim at the conversion of lignin to chemicals is essential for the long-term success of a biorefinery. Herein, we discuss a dithionite-assisted organosolv fractionation (DAOF) of lignocellulose in n-butanol and water to produce cellulosic pulp and mono-/oligo-aromatics. The present study frames the technicalities of this biorefinery process and relates them to the features of the obtained product streams. Via the extensive characterization of the solid pulp (by acid hydrolysis-HPLC, ATR-FTIR, XRD, SEM and enzymatic hydrolysis-HPLC), of lignin derivatives (by GPC, GC-MS/FID, 1H-13C HSQC NMR, and ICP-AES) and of carbohydrate derivatives (by HPLC) we comprehensively identify and quantify the different products of interest. These results were used for inspecting the economic feasibility of DAOF. The adoption of a dithionite loading of 16.7% w/wbiomass and of an equivolumetric mixture of n-butanol and water, which led to a high yield of monophenolics (~20%, based on acid insoluble lignin, for the treatment of birch sawdust), was identified as the most profitable process configuration. Furthermore, the treatment of various lignocellulosic feedstocks was explored, which showed that DAOF is particularly effective for processing hardwood and herbaceous biomass. Overall, this study provides a comprehensive view of the development of an effective dithionite-assisted organosolv fractionation method for the sustainable upgrading of lignocellulosic biomass.

Deep learning has an increasing impact to assist research, allowing, for example, the discovery of novel materials. Until now, however, these artificial intelligence techniques have fallen short of discovering the full differential equation of an experimental physical system. Here we show that a dynamical neural network, trained on a minimal amount of data, can predict the behavior of spintronic devices with high accuracy and an extremely efficient simulation time, compared to the micromagnetic simulations that are usually employed to model them. For this purpose, we re-frame the formalism of Neural Ordinary Differential Equations to the constraints of spintronics: few measured outputs, multiple inputs and internal parameters. We demonstrate with Neural Ordinary Differential Equations an accel- eration factor over 200 compared to micromagnetic simulations for a complex problem – the simulation of a reservoir computer made of magnetic skyrmions (20 minutes compared to three days). In a second realization, we show that we can predict the noisy response of experimental spintronic nano-oscillators to varying inputs after training Neural Ordinary Differential Equations on five milliseconds of their measured response to a different set of inputs. Neural Ordinary Differential Equations can therefore constitute a disruptive tool for developing spintronic applications in complement to micromagnetic simulations, which are time-consuming and cannot fit experiments when noise or imperfections are present. Our approach can also be generalized to other electronic devices involving dynamics.

Sodium and iron make up the perfect combination for the growing demand for sustainable energy storage systems, given the natural abundance and sustainability of the two building block elements. However, most sodium–iron electrode chemistries are plagued by intrinsic low energy densities with continuous ongoing efforts to solve this. Herein, the chemical space of a series of (meta)stable, off-stoichiometric Fe-PO4-F phases is analyzed. Some are found to display markedly improved electrochemical activity for sodium storage, as compared to the amorphous or thermodynamically stable phases of equivalent composition. The metastable crystalline Na1.2Fe1.2PO4F0.6 delivers a reversible capacity of more than 140 mAh g−1 with an average discharge potential of 2.9 V (vs Na+/Na0) resulting in a practical specific energy density of 400 Wh kg−1 (estimated at the material level), outperforming many developed Fe-PO4 analogs thus far, with further multiple possibilities to be explored toward improved energy storage metrics. Overall, this study unlocks the possibilities of off-stoichiometric Fe-PO4-F cathode materials and reveals the importance to explore the oft-overlooked metastable or transient state materials for energy storage.

The use of the spin degree of freedom in thermoelectric conversion offers new functionalities for electronic devices powered by waste heat and a promising solution for sustainable technologies. Here, thermocouples formed from two dissimilar arrays of interconnected magnetic nanowires embedded in a polymer film are used to realize flexible thermoelectric switches providing optimal magnetic-field-induced control of the sign and magnitude of the thermopower. By finetuning the composition of the homogeneous and multilayered nanowires forming the thermocouple legs, an ideal on/off ratio in the switching of the thermoelectric output voltage, or a simple sign reversal can be achieved in the presence of a magnetic field. This work paves the way for flexible spin-caloritronics devices exploiting residual thermal energy for the development of thermally activated sensors and logic devices.

An interesting activation phenomenon: Activation with cycling of a 3.8 V (vs. Na+/Na) redox process in the iron-rich Na0.6Fe1.2PO4 material unlocks new electrochemical mechanism for high-performance, low-cost and eco-friendly Na-ion cathodes

We investigate the impact of the DC current-induced Ampère–Oersted feld on the dynamics of a vortex based spin-torque nano-oscillator. In this study we compare micromagnetic simulations performed using mumax3 and our analytical model based on the Thiele equation approach. The latter is improved by adding two important corrections to the Thiele equation approach. The frst is related to the magneto-static contribution and depends on the aspect ratio of the magnetic dot. The second is a full analytical description of the Ampère–Oersted feld contribution. The model describes quantitatively the simulation results in the resonant regime as well as the impact of the Ampère–Oersted feld. Depending on the relative orientation between the vortex in-plane curling magnetisation (chirality) and the Ampère–Oersted feld a strong splitting phenomenon appears in the fundamental properties (frequency and vortex core position) of the nano-oscillator. Thus, we show that the Ampère–Oersted feld should not be neglected as it has a high impact on the spin-torque vortex oscillator dynamics.

Batteries are recognized as one of the most important energy storage systems due to their high energy density. As one of the most promising next-generation high energy density storage devices, lithium metal batteries have reached momentum. However, the use of lithium metal meets many technical problems with conventional liquid electrolytes, which can be solved by using solid-state electrolytes. Solid-state electrolytes are thus a key component of all-solid-state lithium metal batteries, and their progress directly affects the industrialization of all-solid-state lithium metal batteries. The current research on solid-state electrolytes focuses on two major types of materials: polymers electrolytes and inorganic electrolytes. Polymer electrolytes are a promising class of materials due to their easy processing, lightweight, flexibility, and they provide a feasible solution to safety issues. In this thesis, we introduce phosphonate-containing polymers in polymer electrolytes. Those are very promising compounds because of their good thermal stability, their ability to bind to metals, and excellent flame retardancy. Those novel phosphonate-containing polymers used in polymer electrolytes could maintain the electrolyte-electrode contact interface, prevent the growth of lithium dendrites, increase the electrochemistry stability window, and improve battery safety because of fire-retardant property. This opens the possibility to safely apply Li-metal as a high-capacity anode, which could provide a valuable strategy towards high-performance all-solid-state lithium metal batteries., (SC - Sciences) -- UCL, 2022

Thermoplastic elastomers (TPEs) are an extremely versatile class of engineering plastics that are suitable for many applications thanks to their high extensibility, reversible elasticity, and tunable hardness. They are widely used as fibers, cable insulators, medical devices, shoe soles, and many other applications. Additionally, like many other thermoplastic polymers, they are recyclable and can be easily processed. However, regardless of their exact chemical structure, many TPEs show a decline in their mechanical properties, such as toughness and ductility, at high temperatures. This behavior is in sharp contrast with standard thermoplastics and limits the range of applications where TPEs can be used as a replacement for thermoset rubbers. Understanding the different dynamics behind this behavior and finding out the key parameters that influence the high-temperature mechanical properties is critical to designing new TPEs and targeting new applications where traditional rubbers can be replaced. In this thesis, we explore the high-temperature and high-deformation mechanical properties of a model series of industrially relevant soft TPEs. Through a series of mechanical and morphological tests, we investigate the fundamental relationships between microstructure and mechanical properties. The ultimate aim is to draw a unifying picture that can describe which dynamics influence the deformation behavior and how they interplay with each other., (FSA - Sciences de l'ingénieur) -- UCL, 2022

Background: Homeopathy is highly controversial. The main reason for this is its use of very highly dilute medicines (high homeopathic potencies, HHP), diluted beyond the Avogadro/Loschmidt limit. Research using Nano Tracking Analysis has demonstrated the presence of particles in HHPs. This study aims to verify the results of a previous publication that identified the ionic composition of these particles in all dilutions. Methods: We used Scanning Electron Microscopy & Energy Dispersive X-Ray Spectroscopy (SEM-EDX) to examine dilutions of a commonly used homeopathic medicine, an insoluble metal, Cuprum metallicum, for the presence of particles (NPs). The homeopathic medicines tested were specially prepared according to the European pharmacopoeia standards. We compared the homeopathic dilutions/dynamizations of copper with simple dilutions and dynamized lactose controls. Results: We observed an ionic diversity common to all preparations including HHPs but also significant differences in the relative quantity of each ion between manufacturing lines of homeopathic copper and lactose controls. The probability that the observed differences could have occurred chance alone (especially above Avogadro limit) can be rejected at p < 0.001. The essential component of these homeopathic medicines is sodium hydrogen carbonate, modulated by some other elements and by its quantity, size and shape. Conclusion: Homeopathic medicines made of Cuprum metallicum do contain material with a specific ionic composition even in HHPs diluted beyond the Avogadro/Loschmidt limit. This specificity can be attributed to the manufacturing process. This material demonstrates that the step-by-step process (dynamized or not) does not match the theoretical expectations of a dilution process. The starting material and dilution/dynamization method influences the nature of these NPs. Further measurements are needed on other raw materials using the same controls (solvent and simply diluted manufacturing line

A major societal issue of disposal and environmental pollution is raised by the enormous and fast-growing production of single-use polyethylene terephthalate (PET) bottles, especially in developing countries. To contribute to the problem solution, an original route to recycle PET in the form of value-added environmentally friendly thermoplastic composites with banana fibres (Musa acuminata) has been developed at the laboratory scale. Banana fibres are a so far undervalued by-product of banana crops with great potential as polymer reinforcement. The melt-processing constraints of commercial PET, including used bottles, being incompatible with the thermal stability limits use of natural fibres; PET has been modified with bio-sourced reactants to produce co-polymers with moderate processing temperatures below 200°C. First, commercial PET were partially glycolyzed with 1.3-propanediol to produce co-oligomers of about 20 repeating units, which were next chain extended with succinic anhydride and post-treated in a very unusual “soft solid state” process at temperatures in the vicinity of the melting point to generate co-polymers with excellent ductility. The molar mass build-up reaction is dominated by esterification of the chain ends and benefits from the addition of succinic anhydride to rebalance the acid-to-hydroxyl end-group ratio. Infra-red spectroscopy and intrinsic viscosity were extensively used to quantify the concentration of chain ends and the average molar mass of the co-polymers at all stages of the process. The best co-polymers are crystallisable, though at slow kinetics, with a Tg of 48°C and a melting point strongly dependent upon thermal history. The composites show high stiffness (4.8 GPa at 20% fibres), consistent with the excellent dispersion of the fibres and a very high interfacial cohesion. The strong adhesion can be tentatively explained by covalent bonding involving unreacted succinic anhydride in excess during solid stating. A first approach to

Coordination polymers (CPs) made of redox-active organic moieties and metal ions emerge as an important class of electroactive materials for battery applications. However, the design and synthesis of high voltage alkali-cation reservoir anionic CPs remains challenging, hindering their practical applications. Herein, we report a family of electrically conducting alkali-cation reservoir CPs with the general formula of A2-TM-PTtSA (wherein A = Li+, Na+, or K+; TM = Fe2+, Co2+, or Mn2+; and PTtSA = benzene-1,2,4,5-tetra-methylsulfonamide). The incorporation of transition metal centers not only enables intrinsic high electrical conductivity, but also shows an impressive redox potential increase of as high as 1 V as compared to A4-PTtSA analogues, resulting in a class of organometallic cathode materials with a high average redox potential of 2.95–3.25 V for Li-, Na- and K-ion batteries. A detailed structure – composition – physicochemical properties – performance correlation study is provided relying on experimental and computational analysis. The best performing candidate shows excellent rate capability (86% of the nominal capacity retained at 10C rate), remarkable cycling stability (96.5% after 1000 cycles), outstanding tolerance to low carbon content (5 wt%), high mass loading (50 mg cm−2), and extreme utilisation conditions of low earth orbit space environment tests. The significance of the disclosed alkali-ion reservoir cathodes is further emphasized by utilizing conventional Li-host graphite anode for full cell assembly, attaining a record voltage of 3 V in an organic cathode Li-ion proof-of-concept cell.

Dual-cross-linked networks (DCNs), interpenetrating polymer networks (IPNs), and IPN-derived double networks (DNs) are increasingly utilized to fabricate hydrogels with unique mechanical properties. However, the relationship between the topology of these networks and the resulting dynamics is rarely compared and little understood. To tackle this shortcoming, this work presents a systematic investigation of the viscoelastic properties of DCN, IPN, and DN hydrogels as well as their corresponding single networks by oscillatory shear rheology using both frequency and strain sweeps. All the hydrogels are based on the same orthogonal combination of a supramolecular interaction: zinc(II)-terpyridine bis-complexes, and of a reversible covalent bond: oxime, as cross-links. To understand the contribution of each sub-network to the properties of the DCN, IPN, and DN hydrogels, the corresponding single networks, i.e., cross-linked by only one type of bond, are first studied in detail. All double dynamics hydrogels have a plateau modulus much higher than the sum of the plateau modulus of the single networks, evidencing a synergetic effect between the sub-networks. However, the origin of this modulus increase varies according to the network topology. We also show that the relaxation behaviors of the DCN, IPN, and DN hydrogels are influenced by the dynamics of the corresponding single dynamic networks. Finally, the strain sweeps reveal that, for all network topologies, the amplitude of deformation at which the linear viscoelastic region of the double dynamics networks stops is governed by the oxime network, while the metallo-supramolecular network governs the amplitude of deformation up to which the sample can resist before starting to break.

We investigate the viscoelastic properties of double dynamic networks (DDNs) based on side-functionalized PnBA chains. One of these networks is highly crosslinked by metal-ligand junctions characterized by a fast association/dissociation dynamics, while the other network is sparsely crosslinked with slow dynamic covalent networks (DCNs). We first show that modulating the dynamics of the metallosupramolecular networks, by playing with the temperature, the density of reversible junctions, or the stress applied, has direct consequences on the local equilibration of the DCN. The latter takes place by a constraint release Rouse process at the rhythm of the association/dissociation of the metal-ligand junctions. Then, based on creep-recovery experiments, we investigate the ability of the DDNs to recover their initial shape after a creep test and show again the important role played by the metallosupramolecular network. In particular, the sample recovery strongly depends on the network connectivity, which is enhanced if a denser metallosupramolecular network is used as it reduces the possible creep of the double dynamic network and increases its elastic memory. The sample recovery also depends on the association-dissociation dynamics of the metallosupramolecular bonds as it fixes how fast the stretched DCN can come back to its equilibrium conformation and can recover its initial shape after a large deformation has been applied. Adjusting the dynamics of the weak network is thus a key process to govern the viscoelastic response of the slow network.

We study the linear viscoelastic properties of polymeric networks formed by poly(n-butyl acrylate) telechelic stars end-capped with 2,2:6,2″-terpyridine (Star-PnBA-tpy4) and two types of metal-ligand cross-links with different lifetimes. The influence of interactions, mediated by temperature, nature of metal ions, and ion content, on the linear viscoelastic behavior of both single and double dynamics transient networks is systematically investigated by small amplitude oscillatory shear and creep rheometry. The experimental results reveal that the dynamics of networks with two different metal-ligand cross-links is much faster than expected, characterized by the average sticker lifetime rather than a discrete contribution of each metal-ligand complex. We model the dynamics with the help of our modified tube-based time marching algorithm by accounting for both association/dissociation dynamics of metal-ligand coordination and the entanglement dynamics. Two parameters are defined in the model, namely, the proportion of dangling ends and the average time during which a sticker is free. This allows us to quantify the transient dynamics of the network and, in particular, to determine how the sticker dynamics depend on temperature and ion content.

We present a systematic experimental study of the shear rheology of metallosupramolecular assemblies based on entangled telechelic star polymers comprising one (single dynamic network) or two (double dynamics network) types of physical bonds with the aim to unravel the role of concentration and strength of these bonds on the nonlinear response. Model dynamic networks functionalized with terpyridine ligands were formed by adding different metal ions with increasing bonding strength, zinc, copper, and cobalt. The dynamics are driven by entanglement/disentanglement processes and a ligand exchange mechanism. Steady-state viscosities of single and double dynamics networks collapse onto a universal curve over a wide range of Weissenberg numbers based on terminal time (up to about 300 for single and 1000 for double), exhibiting stronger shear thinning (with an exponent of −0.76) compared to entangled neutral star polymers. Double dynamics networks consisting of two different metal ions (with different lifetimes) exhibit stronger mechanical coherence (rate-dependent fractional viscosity overshoot) and accumulate larger strain at steady-state flow compared to single-ion counterparts. The shear stress growth function signals exhibit weak, albeit unambiguous shear strain hardening, which becomes more pronounced for stronger associations. They also exhibit double overshoot, which reflects the interplay of association strength and chain deformation. Increasing the strength of associations leads to the failure of the Cox–Merz rule, which is more severe for single dynamic networks. The markedly different behavior of double dynamics networks is attributed to the fact that at sufficiently high ion content, the weaker bond acts as a sacrificial component, which provides local energy dissipation and enhances the overall deformability. This bears analogies with their linear viscoelastic response, which has revealed that the arm disentanglement (delayed due to the reversible bonds) effe

Magneto-responsive nanocomposites are prepared by mixing 1–5 vol % of Fe nanoparticles (NPs) in a metallo-supramolecular network made of poly(n-butyl acrylate) (PnBA) bearing terpyridine side groups and cross-linked by the addition of different amounts of Zn2+ ions. To have a clear understanding of the stepwise increase of complexity, the thermomechanical behavior of these materials was characterized through shear linear rheology at each step of their preparation. The metallo-supramolecular networks reveal a clear transition from polymer- to network-driven dynamics when passing progressively from low (<0 °C) to high temperature. While terpyridine (TPy)–Zn2+ complexes are usually treated as independent “stickers”, the analysis of our master curves strongly suggests their aggregation. After the addition of 1–5 vol % of Fe nanoparticles within the supramolecular networks, we evidence the presence of TPy–NP bonds, resulting in a hybrid network of much longer relaxation time. Lastly, we combine thermal imaging and induction heating to emphasize the signature of sticker dissociation, offering new technical solutions to deepen our fundamental understanding of supramolecular networks.

This work focuses on the temperature-dependent structural and rheological characterization of polystyrene-b-poly(n-butyl acrylate)-b-polystyrene triblock copolymers (PS-b-PnBA-b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature (LDOT). To this aim, copolymers of varying block lengths, but keeping the PnBA block as a major component, were synthesized. Small-angle x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature, these copolymers exhibit higher moduli compared to a PnBA homopolymer due to the reinforcing effect of the PS but are flowing at temperatures above the glass transition of the PS. Increasing the PS and PnBA block length, to keep the same PS fraction, induces more profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures.

Due to their memristive properties nanowire networks are very promising for neuromorphic computing applications. Indeed, the resistance of such systems can evolve with the input voltage or current as it confers a synaptic behaviour to the device. Here, we propose a network of silver nanowires (Ag-NWs) which are grown in a nanopourous membrane with interconnected nanopores by electrodeposition. This bottom-up approach fabrication method gives a conducting network with a 3D architecture and a high density of Ag-NWs. The resulting 3D interconnected Ag-NW network exhibits a high initial resistance as well as a memristive behavior. It is expected to arise from the creation and the destruction of conducting silver filaments inside the Ag-NW network. Moreover, after several cycles of measurement, the resistance of the network switches from a high resistance regime, in the GOhm range, with a tunnel conduction to a low resistance regime, in the kOhm range.

The precise design of chain molecules is exploited by living organisms to, e.g., store information, catalyze reactions, or guide assembly processes. Reaching such a degree of precision in synthetic chains not based on peptides nor nucleic acids can nowadays be achieved for oligomers of moderate length. In this context, we have developed a flexible synthetic route of functional oligo(triazole-urethane)s, allowing us to install a wide range of chemical groups in a specific sequence along short chains of precise length and chirality. Among these, we have especially focused on groups active in the trifunctional catalytic aerobic oxidation of alcohols, and on hydrogen-binding groups derived from nucleobases (recognition units). When oligomers bearing the three groups involved in this catalytic cycle are attached along trimeric chains, a very strong effect of sequence on catalytic activity is observed, with a factor of up to ten measured between the best and worse sequences. This can be partly explained by network graphs obtained from molecular dynamics simulations, showing how non-active groups of the chain backbone may prevent the catalytic groups to be spatially close and cooperate in the catalytic cycle, depending on sequence. We also synthesized more complex hexameric chains bearing complementary recognition units and elements of the catalytic triad, which are not independently active but assemble in solution to form a quaternary catalytically-active structure. This results in a catalytic turn-over frequency (TOF) whose concentration- and temperature-dependence can be correlated to the binding constants of the recognition units measured by NMR titration. In particular, the TOF becomes almost concentration-independent at low temperatures over a large range of concentrations. This behavior is reminiscent of enzymes, although our catalytic moieties are not fixed in a rigid framework as in proteins. Finally, we also started to synthesize chiral oligomeric chains with a p

Polymer networks are created by crosslinked polymer chains. These links can be covalent (permanent) or non-covalent (reversible) with consequent effects on the material properties. Both types of networks have advantages and disadvantages: covalent networks resist flow and creep but are difficult to process and recycle, while non-covalent networks are reversible but susceptible to structural changes in the long term. To overcome these limitations of individual networks, double networks work via the combination of a sacrificial network, which breaks immediately on stress and a structural network which maintains the overall integrity. In this way tough and strong materials are created. The subnetworks of a double network can be covalent or non-covalent, imparting new functionalities to the material. The dynamic nature of non-covalently crosslinked networks makes them an ideal candidate to be studied by rheology, which measures the time and frequency dependent behaviour of materials. Our dynamic networks, studied in the melt state, are based on single and interpenetrating poly(n-butylacrylate) (PnBA) networks built from reversible crosslinks with largely different dynamics. The metallosupramolecular network, based on metal-terpyridine complexes, is highly tuneable according to the type of metal ion used. The dynamic covalent network, based on imine-aldehyde bonds, is slowly exchanging at room temperature and provides contrast to the more rapid metallosupramolecular network. Finally, the slide-ring network which facilitates highly extensible materials through the pulley effect is combined with the metallosupramolecular network. Through different combinations of networks and experimental parameters, we are able to establish a relationship between the structure of these networks and their viscoelastic behaviour measured by rheological techniques. In this thesis, our aim is to understand the dynamics of these networks individually and within the double network structure., (SC - Sciences) -- UCL, 2022

Surface biofunctionalization with proteins is the key to many biomedical applications. In this work, a novel biomolecule immobilization method is proposed and developed. This solvent-free approach relies on the use of large argon gas cluster ion beams to transfer controlled amounts of protein from a solid reservoir to any chosen substrate. This method was explored with a series of peptides and proteins: angiotensin, bradykinin, neurotensin, insulin and lysozyme, which were all successfully transferred. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the deposition pattern, allowed measuring the deposited film thickness and, combined with SDS-PAGE electrophoresis, confirmed the presence of non-fragmented protein molecules on the collectors. Lysozyme enzymatic activity could be detected on the collectors, suggesting the preservation or easy recovery in solution of the three-dimensional structure of at least a fraction of the transferred proteins. Furthermore, lowering the energy per atom in the cluster projectiles down to 1 eV allowed more than 60% of bradykinin molecules to be transferred intact. The possibility to achieve alternate multilayer buildup was demonstrated with the construction of a well-organized trilayer composed of bradykinin, neurotensin and Irganox antioxidant. These results pave the way to well-controlled protein deposition using ion beams and to the investigation of more complex multilayer architectures., (FSA - Sciences de l'ingénieur) -- UCL, 2022

Designing compatible electrode-electrolyte interfaces is critical in order to achieve a high and consistent performance and lifespan in next-generation rechargeable lithium batteries. In the study of nanoscopic interfaces, ab-initio molecular dynamics (AIMD) simulations allow for a highly accurate description of interface dynamics and reactions. However, due to the high computational cost, simulations are limited in the size and time domains and therefore merit the need for a new interpretational approach which can deduce the long-term reactivity from such short yet highly accurate simulations. In this work we introduce a new way to assess this reactivity by performing a total trajectory analysis on the bond length variation for key solid polymer electrolyte functional groups and illustrate the influence of electrode material types and environmental factors such as the temperature and electric field strength on the reactivity.

Solid state batteries are of wide interest owing to their high energy density and safety. Their stability with high voltage cathodes is not new to the researchers and are advantageous in various terms. Although ethylene oxide side chains being one of the most studied system also suffers from serious setback with its prime backbone. Here in our work, we studied the effect of terminal group of linear and tri-arm polyethylene glycol (PEG-OH) by converting it to carbonate-ketone (Carb-ket) from hydroxyl. We synthesized the polyethylene carb-ket (TPEG-carb-ket) terminal by ring opening reaction. The carb-ket functionality at the chain end not only increase the electrochemical stability window > 4.47 V but also limits the parasitic reactions with lithium metal stabilising SEI at the interface. The latter demonstrated the superior galvanostatic charge-discharge of LiFePO4 using as synthesized electrolyte loaded with LiTFSI salts as compare to similar chain length PEG-OH. This make the vast impact on controlling the undesired decomposed products at the interface to facilitate the high coulombic efficiency and capacity retention The TPEG-carb-ket also hinted at stable interface with lithium as a result of stripping and plating for more than 1200 h. These experiment results provide important insights backed by AIMD simulations in comparison with hydroxyl terminal system. Our study would aide with the major step on improving the higher voltage cathode with superior performance in the lithium batteries.

With higher energy density, flexibility, safe operation at both room temperature as well as high temperature, solid-state batteries technology has been strongly looked upon as superior diversion from conventional liquid electrolytes-based lithium batteries. Among various other class of polymers, there is strong need to focus on sustainable and yet better alternatives other than most researched polyethylene oxide (PEO). Poly(hydroxyurethanes) (PHU) owing to their high degree of structural tunability can be interesting candidates for Solid polymer electrolyte (SPE). Here, we synthesized bio-based PHU networks by facile ring-opening polymerization of carbonated soybean oil (CSBO) without catalyst. The existence of polyether and polyester provides the PHU network with soft segments while urethane linkage with hard segments. The lower Tg with higher thermal stability widespread its application at elevated temperature without melting and significant degradation. PHU shows remarkable adhesive properties to the surface of metal speculating better interfacial contact and stability. The electrochemical investigations exhibited decent ionic conductivity (> 10-4 at 60o C), electrochemical stability window (ESW > 4.5 V vs. Li/Li+) and transport properties allowing it to be explored for high voltage cathodes. Lithium ferrophosphate (LiFePO4) cells with PHU also demonstrated promising charge-discharge (> 100 mAhg-1 at 60o C) with the li-metal anode. The attempt to develop bio-based batteries materials are much required added step toward green and clean energy for a sustainable future.

Green resources for lithium-based batteries excite many researchers due to their eco-friendly nature. In this work, a sustainable bio-based solid-state electrolyte was developed based on carbonated soybean oil (CSBO), obtained by organocatalyzed coupling of CO2 to epoxidized soybean oil. CSBO coupled with lithium bis(trifluoromethanesulfonyl)imide salt on a bio-based cellulose separator resulted in free-standing membranes. Those membranes on electrochemical measurements exhibited ionic conductivity of around 10−3 S cm−1 at 100 °C and around 10−6 S cm−1 at room temperature with wide electrochemical stability window (up to 4.6 V vs. Li/Li+) and transference number up to 0.39 at RT. Further investigations on the galvanostatic charge-discharge of LiFePO4 cathodes with CSBO-based electrolyte membranes and lithium metal anodes delivered the gravimetric capacity of 112 and 157 mAh g−1 at RT and 60 °C, respectively, providing a promising direction to further develop bio-based solid electrolytes for sustainable solid-state lithium batteries.

Herein, we describe the synthesis of the first boron nitride-doped polyphenylenic material obtained through a [4 + 2] cycloaddition reaction between a triethynyl borazine unit and a biscyclopentadienone derivative, which undergoes organogel formation in chlorinated solvents (the critical jellification concentration is 4% w/w in CHCl3). The polymer has been characterized extensively by Fourier-transform infrared spectroscopy, solid-state 13C NMR, solid-state 11B NMR, and by comparison with the isolated monomeric unit. Furthermore, the polymer gels formed in chlorinated solvents have been thoroughly characterized and studied, showing rheological properties comparable to those of polyacrylamide gels with a low crosslinker percentage. Given the thermal and chemical stability, the material was studied as a potential support for solid-state electrolytes. showing properties comparable to those of polyethylene glycol-based electrolytes, thus presenting great potential for the application of this new class of material in lithium-ion batteries.

Solid-state polymer electrolytes are key components for future batteries with higher energy density as well as increased safety and processability. In this context, a solid polymer electrolyte is developed from statistical copolymers containing flame-retardant phosphonate units and ion-conductive cyclocarbonate moieties mixed with lithium salts. Ionic conductivity measured at room temperature for those copolymers (≈10−5 S cm−1) are in the same range as typical solid polymeric electrolytes not based on poly(ethylene oxide). Moreover, those copolymers electrolytes are stable in a wide electrochemical window (0.5 – 4.5 V vs Li+/Li) and at high temperature (>120 °C) and they lead to a better ionic conductivity than the corresponding homopolymer blends of a similar composition, which is explained by a better lithium salt solubility and better-defined ion-conduction pathways in case of the copolymer. Finally, it has demonstrated the possibility to have fire-retardant properties afforded by phosphonate groups in copolymers without impacting the ionic conductivity.

Designing compatible electrode–electrolyte interfaces is critical to achieve high and consistent performance and life span in next-generation rechargeable lithium batteries. In the study of nanoscopic interfaces, ab initio molecular dynamics (AIMD) simulations allow for a highly accurate description of interface dynamics and reactions. However, due to the high computational cost, simulations are limited in the size and time domains and therefore merit the need for a new interpretational approach that can deduce the long-term reactivity from such short yet highly accurate simulations. In this study, this is established by means of bond length distribution analysis through which the reactivity of key solid polymer electrolyte (SPE) polymer functional groups in contact with key electrode materials (graphite, silicon, lithium) and the influence of the electric field and temperature was successfully determined. Bond length distributions were found to respond to environmental changes and relate to the long-term reactivity in which the strength of electrode surface interactions and the accessibility of functional groups were found to be critical factors. Furthermore, the balancing of the SPE polymer mobility and functional group–electrode surface attraction, respectively, kinetic and thermodynamic properties, further suggests a selective spatial orientation of functional groups when exposed to an electric field, which could have great implications for low-temperature and high-current-density environments. The obtained knowledge on how reactive key SPE polymer functional groups are and also how their reactivity changes in terms of the electric field orientation effect could provide new insights for designing new stable SPE polymers.

Titania-silica (TiO2-SiO2) mixed oxides are known catalysts for the epoxidation of olefins. It has been demonstrated that their active sites consist in isolated framework Ti atoms. However, the latter species are only obtained when Ti loading is low, limiting the number of active sites and the catalytic performances. Thus, the need to search other approaches to boost them. We succeeded improving the catalytic activity of TiO2-SiO2 mixed oxides in the epoxidation of cyclooctene with hydrogen peroxide by introducing hydrophobic organic moieties at their surface. Hydrophobic TiO2-SiO2 mixed oxides were prepared through a one-pot sol-gel method. Titanium butoxide (TiBut) and tetraethoxy silane (TEOS) were used as the Ti and Si precursors respectively. Hydrophobization was achieved by substituting a fraction of TEOS in the synthesis by methyltriethoxy silane (MTES). The characterization of the Ti species was performed by FTIR, DRUV, and XPS, confirming the presence of significant amount of the active framework Ti. The methylation degree was evaluated by Solid State 29Si-NMR and TGA-MS. Hydrophobic TiO2-SiO2 performed better in the epoxidation reaction than a fully inorganic more hydrophilic TiO2-SiO2 prepared without MTES. A too high methylation degree of the catalysts is however detrimental. Our contribution allows elucidating the debate in literature about the consequence of hydrophobization of epoxidation catalysts on their performance.

Fiber reinforced polymer (FRP) composites offer many advantages such as lightweight and high strength motivating their intensive use in aircrafts. However, the manufacturing of complex composite parts often requires bonding composite parts in an efficient way [1]. Adhesives can be used, but with low to moderate toughness [2] and difficulties to develop integrated manufacturing approaches. Several strategies have been proposed to increase the joint toughness. One option is replacing the adhesive by a thermoplastic film, but which necessitates a tough thermoplastic-thermoset interphase. Recently, Voleppe et al. observed an enhanced fracture resistance of thermoplastic/thermoset interfaces owing to a crack trapping mechanism in a morphological gradient when inserting a PEI film in the epoxy resin RTM6 [3]. The interface is characterized by a fracture toughness equal to 800J/m², similar to that of good structural adhesives for composite bonding, while the one of the epoxy resin is only about 100 J/m². The crack is trapped between the PEI film and a co-continuous morphology (Figure 1). The goal of the current research is to apply this concept to composite bonding and to better understand this toughening mechanism.

Immobilization of single antioxidant enzyme systems was frequently studied in the past, however, there is a lack of reliable reports on the co-immobilization of such enzymes. Here, an antioxidant enzyme cascade involving superoxide dismutase (SOD) and horseradish peroxidase (HRP) was successfully immobilized on titania nanosheets (TNS) by the sequential adsorption method using poly(diallyldimethylammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS) polyelectrolyte building blocks. The development of the cascade system was based on a colloid approach, in which the charging and aggregation processes were optimized in each synthetic step. The polyelectrolyte and enzyme multilayers were built up in two different sequences at the particle interface, namely, TNS-PDADMAC-SOD-PSS-HRP and TNS-HRP-PDADMAC-SOD-PSS. The formation of the polyelectrolyte layers led to charge reversal of the carrier and the saturated PDADMAC and PSS layers stabilized the dispersions, in particular, their resistance against salt-induced aggregation was especially excellent. The results of enzymatic assays revealed that the SOD and HRP-like activities of the composites depended on the location of the enzymes in the hybrid material. The obtained compounds showed remarkable antioxidant effect and were able to simultaneously decompose superoxide radical anions and hydrogen peroxide. The cascade systems are of great promise in industrial manufacturing processes during the preparation of high-quality products without any damages by reactive oxygen species.

Introduction and Objective : Whereas tissue engineering research has hugely grown up, few decellularization methods are used to decrease cell immunogenicity. However, differences between treatments with and without soaps have not yet been evaluated. This study compared 5 different protocols applied to human periosteum (HP) and fascia lata (HFL). Morphological, structural and cytotoxic/viability analysis were performed to confront research procotols (with soap) and the clinical one (without soap).[...]

New solid polymer electrolytes are of particular interest for next-generation high-energy batteries since they can overcome the limited voltage window of conventional polyether-based electrolytes. Herein, a flame-retardant phosphorus-containing polymer, poly(dimethyl(methacryloyloxy)methyl phosphonate) (PMAPC1) is introduced as a promising polymer matrix. Free-standing membranes are easily obtained by mixing PMAPC1 with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and a small amount of acetonitrile (AN). LiTFSI/AN mixed aggregates are formed that act as plasticizers and enable ionic conductivities up to 1.6 × 10–3 S cm–1 at 100 °C. The high content of LiTFSI used in our electrolytes leads to the formation of a stable LiF solid-electrolyte interphase, which can effectively suppress Li dendrites and the chemical degradation of AN in contact with Li. Accordingly the electrolyte membranes exhibit a wide electrochemical stability window above 4.7 V versus Li+/Li and fire-retardant properties due to the presence of the phosphorus-containing polymer. Atomistic molecular modeling simulations have been performed to determine the structure of the electrolytes on the microscopic scale and to rationalize the trends in ionic conductivity and the transport regime as a function of the electrolyte composition. Finally, our electrolyte membranes enable stable cycling performance for LiFePO4|PMAPC1 + LiTFSI + AN|Li batteries.