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We report on the use of atomic force microscopy (AFM) to identify and characterize an intermediate state in macrocycle shuttling in a hydrogen bonded amide-based molecular shuttle. The [2]rotaxane consists of a benzylic amide macrocycle mechanically locked onto a thread that bears both fumaramide and succinic amide-ester sites, each of which can bind to the macrocycle through up to four intercomponent hydrogen bonds. Using AFM-based single-molecule force spectroscopy, we mechanically triggered the translocation of the ring between the two principal binding sites ("stations") on the axle. Equilibrium fluctuations reveal another interacting site involving the two oxygen atoms in the middle of the thread. We characterized the ring occupancy distribution over time, which confirms the intermediate in both shuttling directions. The study provides evidence of weak hydrogen bonds that are difficult to detect using other methods and shows how the composition of the thread can significantly influence the shuttling dynamics by slowing down the ring motion between the principal binding sites. More generally, the study illustrates the utility that single-molecule experiments, such as force spectroscopy, can offer for elucidating the structure and dynamics of synthetic molecular machines.

The combination of inorganic heterogeneous catalysts and enzymes, in so-called hybrid chemoenzymatic heterogeneous catalysts (HCEHCs), is an attractive strategy to effectively run chemoenzymatic reactions. Yet, the preparation of such bifunctional materials remains challenging because both the inorganic and the biological moieties must be integrated in the same solid, while preserving their intrinsic activity. Combining an enzyme and a zeolite, for example, is complicated because the pores of the zeolite are too small to accommodate the enzyme and a covalent anchorage on the surface is often ineffective. Herein, we developed a new pathway to prepare a nanostructured hybrid catalyst built from glucose oxidase and TS-1 zeolite. Such hybrid material can catalyse the in situ biocatalytic formation of H2O2, which is subsequently used by the zeolite to trigger the epoxidation of allylic alcohol. Starting from an enzymatic solution and a suspension of zeolite nanocrystals, the hybrid catalyst is obtained in one step, using a continuous spray drying method. While enzymes are expectedly unable to resist the conditions used in spray drying (temperature, shear stress, etc.), we leverage on the preparation of “enzyme– polyelectrolyte complexes” (EPCs) to increase the enzyme stability. Interestingly, the use of EPCs also prevents enzyme leaching and appears to stabilize the enzyme against pH changes. We show that the one-pot preparation by spray drying gives access to hybrid chemoenzymatic heterogeneous catalysts with unprecedented performance in the targeted chemoenzymatic reaction. The bifunctional catalyst performs much better than the two catalysts operating as separate entities. We anticipate that this strategy could be used as an adaptable method to prepare other types of multifunctional materials starting from a library of functional nanobuilding blocks and biomolecules.

A series of tunable interpenetrating polymer network (IPN) hydrogels are designed by the orthogonal incorporation of two distinct types of reversible bonds, i.e., Schiff base bonds and metal–ligand...

The immobilization of multiple functional groups on mesoporous silica has provided opportunities to emulate the unique design principles and performances of enzymes. In this direction, it is essential to master the cooperative behavior of active surface-bound molecules to arrive at heterogeneous, recyclable catalysts with enhanced or novel properties compared to the parent system in solution. With the advances in sol-gel and surface chemistry, it is now possible to prepare silica-supported multifunctional catalysts that can combine most of the activation modes of organic chemistry. Further tailoring the surface ratio and proximity of the confined activating functional groups affords ways to refine the probability of synergistic interactions within the active site. Yet, the systematic evaluation and engineering of the spatial distribution of surface functional groups, which are more often randomly arranged within the pore channels, rises the next key challenge towards a more rational design of bioinspired supported catalysts.

Vinylidene fluoride (VDF)-based copolymers bearing pendant perfluoroalkyl ether groups for potential application in gel polymer electrolytes were synthesized via conventional radical copolymerization of VDF with a 2-trifluoromethacrylate monomer bearing pendant perfluoroalkyl ether groups [2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-(perfluoropropoxy)propoxy]propyl 2-(trifluoromethyl)acrylate (MAF-PFE)]. Two kinds of initiators (hydrogenated and a perfluorinated highly branched persistent radical that released CF3• radical from 80 °C) were used. Molar masses ranged between 35 000 and ca. 50 000 g·mol–1. The synthesized poly(VDF-co-MAF-PFE) copolymers were evaluated in gel polymer electrolytes based on ionic liquids. With this aim, the poly(VDF-co-MAF-PFE) copolymers were mixed with lithium bis(trifluoromethanesulfonyl)imide and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Homogeneous gels with conductivity values at room temperature reaching up to 3 × 10–3 S·cm–1 were obtained, while the transference number of lithium ions was 0.12 at 40 °C. Finally, such electrolytes displayed an electrochemical stability window between 1.5 and 4.4 V as determined by cyclic voltamperometry measurements.

Argon gas cluster ion beams (Ar-GCIBs) provide new opportunities for molecular depth profiling and imaging of organic materials and biological samples, thanks to recent technological developments that have led to the construction of new SIMS spectrometers where the traditional issues related to their low lateral resolution along with poor mass resolution and mass accuracy are overcome. The present fundamental contribution on SIMS molecular depth profiling investigates the variations of the secondary ion signals observed at the organic–inorganic hybrid interface when using Ar-GCIB as the analytical beam. With this in mind, depth profiling experiments were performed with a ToF-SIMS spectrometer using different analysis beams: 30-keV Bi5+ versus 10-keV Arn+ with a cluster size (n) of 800, 1500, 3000 and 5000 atoms, respectively. A 10-keV Ar3000+ beam was used for sputtering in all the experiments. Irganox 1010 and model polymers such as polystyrene (PS) and poly (methyl methacrylate) (PMMA) oligomers were chosen. Silicon wafer and a polymer-based substrates were employed to test materials with different stiffness, which is directly related to their Young’s moduli, an important parameter in this study. Ar-GCIB depth profiles systematically show ion signal enhancement of the characteristic fragments of PS and Irganox 1010 when approaching the interface with the silicon substrate, that can reach up to 60% for [M1010-H]− in Irganox films deposited onto silicon wafers. This enhancement increases with increasing n in both ion polarities. These results point out some ionization effects on the observed signal enhancement at the interface. The experimental observations will be explained on the basis of the physics of the impact of large argon clusters on different target materials and the energy confinement of the ion projectile in the organic overlayers. Finally, the thickness of organic films on rigid substrates in the nanoscale appears to be a crucial parameter to dramatically improve the sensitivity to molecular fragments when using large Ar cluster ions as analysis beams.

Because electromagnetic (EM) pollution of the environment is becoming such a pervasive issue, highly efficient solutions for EM protection are being keenly sought for. Our approach provides new avenues to simple, compact, and efficient broadband microwave absorbers designed to cancel EM interferences in the microwave range. The paper demonstrates the potential of a clever organization of nanoscaled inclusions (carbon nanotubes, graphene, magnetic metallic nanowires or nanoparticles) in polymer matrices for controlling the electromagnetic propagation at wavelengths ranging from millimeters up to tenths of centimeters, with a particular focus on broadband absorption. Controlled architectures of polymer composites loaded with various nanofillers, and in particular layered stacks of composite films enable optimization of the absorption bandwidth while preserving the compactness of the structure. First, various carbon-based and metallic nanofillers are synthesized. Next, nanofillers are dispersed in a polymer matrix thanks to melt polymer processing and dispersion techniques. The absorption characteristics of resulting thin composite slabs are first characterized. Various combinations of superposed slabs are then investigated and modelled in order to optimize the absorption of the resulting multilayers. The performances of the investigated structures are finally compared with the help of a new figure of merit combining the maximum absorption and its bandwidth.

Cu-Ni alloys are extensively used in contact with natural waters and are impacted by microbial activities of biofilms. The mechanisms by which surface changes occur upon immersion remain not well understood. Herein, an aerobic microbial activity of natural biofilms is mimicked by the enzymatic generation of an oxidizing agent and an organic acid. Surface changes are probed through a detailed analysis of XPS spectra which allowed a distinction between compounds of organic and inorganic nature to be made. Results show that the surface is composed of copper oxides/hydroxides, presumably Cu2O and Cu(OH)2 and Ni hydroxides. The enzyme-catalyzed reaction causes a significant depletion of Ni and inorganic oxygen, while the concentration of copper, CuI and CuII, varies only slightly. Surface changes concern the organic phase; the amount of organic compounds strikingly increases in the presence of enzymes, and the XPS spectra reveal the accumulation of compounds with high oxidized carbon content, attributed to adsorbed gluconate. Correlations between spectral data suggest the formation of Cu-gluconate complex, probably through coordinative bonds between gluconates and CuII on the oxide layer. These findings are particularly important to properly evaluate the impact of microbial activities on the sustainability of Cu-Ni alloys upon natural exposures.

Surface and thin films are important in modern technologies and there is growing demand for their characterization. Secondary ion mass spectrometry (SIMS) is universally used for extracting information on the chemical composition of surfaces. This study shows that it can provide information about the physical (mechanical) properties of thermoset polymer surfaces. The intensities of backscattered Arn+ clusters were measured upon 10 keV Ar3000+ gas cluster ion bombardment of polymer films. Tyrosol diaminodiphenylmethane based benzoxazine thermosets with different curing cycles were used. The intensity ratios Ar2+/(Ar2++Ar3+) and Ar2+/(Ar2++Ar4+) were highly sensitive to the physical changes of the thermoset coating surfaces as a function of their curing cycle and of temperature. These intensity ratios provide direct access to the surface transition temperature TT (related to the bulk glass transition Tg), and show a dependence on the curing degree below and above TT. Moreover, we discuss the influence of surface contamination and clusters induced roughness on the measured values. Our results suggest that contamination has a dramatic influence on the intensity of backscattered Arn+ clusters, while that of roughness appears to be minor. This study constitutes a step forward towards a quantitative assessment of the mechanical properties of polymer coating surfaces using SIMS.

Ethanol dehydration is effectively catalyzed by solid acids, such as HZSM-5, alumina, or silica-alumina. In these catalysts, the amount, nature, and strength of acid sites is believed to determine catalyst activity and stability. However, surface hydrophilicity or hydrophobicity can be suggested as another decisive materials property that can directly influence performance. For example, a more hydrophobic surface might be beneficial in repelling the co-product of the reaction, water. However, these aspects have been studied only scarcely in the context of alcohol dehydration. Here, a series of mesoporous hybrid aluminosilicate materials containing CH3Si groups was prepared in one pot by non-hydrolytic sol-gel (NHSG). The presence of the methyl groups was verified by IR, solid-state NMR, and ToF-SIMS. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. Two parameters were varied: (i) the aluminum loading (Si : Al ratio) and (ii) the degree of methylation (Si : MeSi ratio). On the one hand, changing the Si : Al ratio had a marked and expected impact on acidity. On the other hand, unexpectedly, the introduction of methyl groups had no clear influence on sample hydrophobicity. Nevertheless, some of the methylated aluminosilicate catalysts markedly outperformed the purely inorganic catalysts and a commercial silica-alumina benchmark. While a direct influence of surface hydrophilicity or hydrophobicity is unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts is correlated with a modification of the acidic properties (higher proportion of Lewis acid sites) caused by the introduction of methyl groups during the sol-gel process. A decisive role of acidity in ethanol dehydration was confirmed by an experiment with delayed addition of the Al precursor in the NHSG synthesis of the hybrid aluminosilicate. This led to a higher Al surface concentration, marked acid sites number increase, and better catalytic performance, even competing with the state of the art HZSM-5 in terms of ethylene yield. This journal is

Surface contact electrification experiments have been performed on insulating polyester fibres in contact with a conductive fibre using biased atomic force microscopy tips. With positive tip bias, charge spots have been deposited in a reproducible manner. The density of deposited charges on the fibre surface was observed by Kelvin probe force microscopy as a function of time, charging position and relative humidity. Two main charge dissipation mechanisms were identified with different importance depending on the relative humidity value.

Porous polymeric microcarriers are a versatile class of biomaterial constructs with extensive use in drug delivery, cell culture and tissue engineering. Currently, most methods for their production require potentially toxic organic solvents with complex setups which limit their suitability for biomedical applications and their large-scale production. Herein, we report an organic, solvent-free method for the fabrication of porous poly( l -lactide) (PLLA) microcarriers. The method is based on the spherulitic crystallization of PLLA in its miscible blends with poly(ethylene glycol) (PEG). It is shown that the PLLA spherulites are easily recovered as microcarriers from the blends by a water-based process. Independent control over microcarrier size and porosity is demonstrated, with a higher crystallization temperature leading to a larger size, and a higher PLLA content in the starting blend resulting in a lower microcarrier porosity. Microcarriers are shown to be biocompatible for the culture of murine myoblasts and human adipose stromal/stem cells (hASC). Moreover, they support not only the long-term proliferation of both cell types but also hASC differentiation toward osseous tissues. Furthermore, while no significant differences are observed during cell proliferation on microcarriers of two different porosities, microcarriers of lower porosity induce a stronger hASC osteogenic differentiation, as evidenced by higher ALP enzymatic activity and matrix mineralization. Consequently, the proposed organic-solvent-free method for the fabrication of biocompatible porous PLLA microcarriers represents an innovative methodology for ex vivo cell expansion and its application in stem cell therapy and tissue engineering. Statement of Significance We report a new solvent-free method for the preparation of porous polymeric microcarriers for cell culture, based on biocompatible poly( l -lactide), with independently controllable size and porosity. This approach, based on the spherulitic crystallization in polymer blends, offers the advantages of simple implementation, biological and environmental safety, easy adaptability and up-scalablility. The suitability of these microcarriers is demonstrated for long-term culture of both murine myoblasts and human adipose stromal/stem cells (hASCs). We show that prepared microcarriers support the osteogenic differentiation of hASCs, provided microcarriers of properly-tuned porosity are used. Hence, this new method is an important addition to the arsenal of microcarrier fabrication techniques, which will contribute to the adoption, regulatory approval and eventually clinical availability of microcarrier-based treatments and therapies.

Well‐defined pyrene‐based poly(2,2,6,6‐tetramethylpiperidinyloxy‐4‐yl methacrylate) (PTMA) (co)polymers have been synthesized and combined with multi‐wall carbon nanotubes (CNTs) as electrode material for organic radical batteries. The influence of the number of pyrene pendent groups on the electrochemical response of the nanocomposite materials has been assessed, focusing on the capacity retention upon charge/discharge cycling and on the cycling rate. In parallel, the interactions between the polymethacrylate chains and the CNT surface have been investigated with molecular modeling techniques, to shed light on the nature and stability of the functionalized PTMA/CNT interface.

Multifunctional catalysts obtained by the covalent immobilization of discrete molecular species on porous supports represent a unique approach to emulate some of the design principle and performances of enzymes. However, it is decisive in such systems to control the stoichiometry, spatial distribution, and proximity between the grafted catalytic centers to satisfy the chemical and geometrical requirements for cooperativity. Here, we present strategies to optimize the activity of a catalytic triad on mesoporous silica particles in the representative aerobic oxidation of benzyl alcohol and show that, in contrast with the more-traditional mixed-monolayer approach, activity can be amplified by tuning the spatial distribution of the co-catalysts to maximize the probability of full synergistic pairings.

A remarkable synergistic increase in fracture toughness by 130% is demonstrated for a CFRP high performance epoxy composite when adding an equal weight combination of phenoxy thermoplastic and core-shell rubber (CSR) toughening agents, as compared to a single toughener at a comparable total concentration of around 10 wt%. The dual-toughened matrix exhibits an unusual morphological arrangement of the two toughener agents. The interlaminar shear strength of the composites is also synergistically improved by about 75% as compared to the reference while the compression modulus reduction and viscosity increase are significantly smaller than for the single phenoxy toughened system. A partial filtering of the CSR particles by the dense CF fabric during pre-pregging leads to a less than optimum CSR dispersion in the composites, showing that the synergy can be further optimized, possibly to the same level as the unreinforced systems.

The principle of encapsulation/release of a guest molecule from stimuli responsive hydrogels (SRHs) is mainly realised with pH, temperature or light stimuli. However, only a limited number of redox responsive hydrogels have been investigated so far. We report here the development of a SRH that can release its guest molecule upon a redox stimulus. To obtain this redox hydrogel, we have introduced into the hydrogel the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) stable nitroxide radical, which can be reversibly oxidized into an oxoammonium cation (TEMPO+). Water solubility is provided by the presence of the (oligoethyleneglycol)methacrylate (OEGMA) comonomer. Electrochemical and mechanical characterization showed that those gels exhibit interesting physicochemical properties, making them very promising candidates for practical use in a wide range of applications.

Patterned and layered hydrophilic/phobic coatings were deposited on multiple surfaces using nonfluorinated precursors (AA, acrylic acid; PMA, propargyl methacrylate) with an atmospheric pressure dielectric barrier discharge operating in open air. Water contact angles of the resulting films could be tuned from 135° (very hydrophobic) by adjusting the AA/PMA feed ratio and/or via postdeposition exposure of films to an Ar/O2 plasma treatment. Coatings could be applied to any surface and were seen to be water stable, due in large part to cross-linking induced from the reactivity of the PMA pendant groups. Hybrid hydrophilic/phobic patterns at submillimeter length scales, and philic/phobic/philic laminates were produced using a shadow mask and sequential deposition, respectively. Chemical heterogeneity of films was assessed using XPS, SIMS, and micro-IR imaging and suggest that localization of COOH and OH groups are primarily responsible for hydrophilicity. Overall, this work demonstrates that atmospheric pressure plasma polymerization is a simple and scalable method for robust and tunable control of wettability of surfaces of all kinds., SCOPUS: ar.j, info:eu-repo/semantics/published

Polystyrene-like coatings are synthesized by plasma near atmospheric pressure. Elucidating their chemical structure after exposure to ambient air could be very challenging because of the interference of surface-related phenomena, mainly post-polymerization oxidation and contamination. In this paper, we propose secondary ion mass spectrometry (SIMS) in molecular depth-profiling mode, combined to multivariate analysis, as a more reliable tool for their investigation as a function of the injected power. Indeed, the information provided by the inner layers is more representative of the film in growth. The SIMS approach is validated by complementary, surface-sensitive and bulk techniques: X-rays photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). The SIMS results suggest that the high concentration of -CH 3 groups in the polymer matrix, pointed out by IR, is due to branching and/or grafting of CH 3 · radicals to active sites (prevalently in position α, β, γ) along the aliphatic backbone, in addition to a significant fraction of trapped oligomers. The oligomer contribution is supported by an original study based on the molecular weight dependence of the sputtering efficiency. The overall experimental evidences indicate a milder fragmentation of the precursor at lower powers, leading to a higher conservation of the aromaticity and a lesser branched and/or cross-linked content., SCOPUS: ar.j, info:eu-repo/semantics/published

Recent progress in organic secondary ion mass spectrometry (SIMS) relied essentially on the development of new cluster beams, especially large atomic and molecular clusters formed via the adiabatic expansion of a gas in vacuum (Arn+, [CH4]n+, [CO2]n+, [H2O]n+). Although computer simulations and a few experimental investigations have shed light on certain fundamental aspects of large cluster-induced molecular desorption, the analytical application of these new beams usually preceded the detailed understanding of their interaction with surfaces. Here, to gain insight into the molecular emission process, the axial kinetic energy distributions (KEDs) of secondary ions emitted from organic films bombarded with Ar330–5000+ and Bi5+ clusters were measured using a reflectron time-of-flight secondary ion mass spectrometer. Irganox 1010 was chosen as a model kilodalton molecule because a large body of SIMS data involving this molecule already exists in the literature. Our results show that the axial KED of Irganox molecular and fragment ions varies as a function of the scaled kinetic energy E/n of the Ar cluster projectile and so does the fraction of ions produced above the surface via unimolecular dissociation, which exhibit an energy deficit with respect to the full acceleration provided at the entrance of the spectrometer. Below a few tens of eV/atom, the KEDs of ions such as (M – H)− (m/z 1175) become gradually narrower and their formation via metastable decay in the gas phase above the surface intensifies. Interestingly, the molecular ion M•+ (m/z 1176) is essentially produced in the gas phase with both Arn+ and Bi5+ cluster beams. Specifics of the observed KEDs of negative and positive molecular ions are discussed in comparison with results of other experiments recently reported in the literature and of molecular dynamics (MD) computer simulations using a coarse-grained representation of kilodalton organic molecules. The measurement of the axial kinetic energy of molecular and fragment ions sputtered from Irganox 1010 under argon and bismuth cluster bombardment, complemented with MD simulations, offers a clearer microscopic view of the emission process.

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.

A facile and novel method for the fabrication of core-shell nanoparticles (PTMA@SiO2) based on a poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) core and a porous SiO2 shell is reported. The core-shell nanoparticles are further self-assembled with negatively charged multi-walled carbon nanotubes (MWCNTs), which results in the formation of a free-standing cathode electrode. The porous SiO2 shell not only effectively improves the stability of the linear PTMA redox polymer with low molar mass in organic electrolytes but also leads to the uniform dispersion of PTMA active units in the MWCNTs conductive network. The PTMA@SiO2@MWCNT composite electrode exhibits a specific capacity as high as 73.8 mAh g at 1 C and only 0.11% capacity loss per cycle at a rate of 2 C.

Electronic systems and telecommunication devices based on low-power microwaves, ranging from 2 to 40 GHz, have massively developed in the last decades. Their extensive use has contributed to the emergence of diverse electromagnetic interference (EMI) phenomena. Consequently, EMI shielding has become a ubiquitous necessity and, in certain countries, a legal requirement. Broadband absorption is considered the only convincing EMI shielding solution when the complete disappearance of the unwanted microwave is required. In this study, a new type of microwave absorber materials (MAMs) based on reduced graphene oxide (rGO) decorated with zero-valent Fe@&gamma, Fe2O3 and Fe/Co/Ni carbon-protected alloy nanoparticles (NPs) were synthesized using the Pechini sol-gel method. Synthetic parameters were varied to determine their influence on the deposited NPs size and spatial distribution. The deposited superparamagnetic nanoparticles were found to induce a ferromagnetic resonance (FMR) absorption process in all cases. Furthermore, a direct relationship between the nanocomposites&rsquo, natural FMR frequency and their composition-dependent saturation magnetization (Ms) was established. Finally, the microwave absorption efficiency (0.4 MHz to 20 GHz) of these new materials was found to range from 60% to 100%, depending on the nature of the metallic particles grafted onto rGO.

We demonstrate entrapment of the commensal skin bacteria Staphylococcus epidermidis in mats composed of soft nanotubes made by membrane-templated layer-by-layer (LbL) assembly. When cultured in broth, the resulting nanofibrillar patches efficiently delay the escape of bacteria and their planktonic growth, while displaying high steady-state metabolic activity. Additionally, the material properties and metabolic activity can be further tuned by postprocessing the patches with additional polysaccharide LbL layers. These patches offer a promising methodology for the fabrication of bacterial skin dressings for the treatment of skin dysbiosis while preventing adverse effects due to bacterial proliferation.

End-functionalized poly(3-hexylthiophene) (P3HT) and poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) were synthesized using controlled polymerization techniques and linked together to lead to a diblock copolymer structure via click cycloaddition. These diblock copolymers were further blended with carbon nanotubes (CNTs) to be used as cathodes in organic radical batteries. The performances of these batteries were studied during charge/discharge cycling at constant and variable current densities (C rate). In order to shed light on the importance of the diblock copolymer architecture, the results were compared to the capacities measured on electrodes made of blends of P3HT and PTMA homopolymers. Theoretical simulations were finally used to corroborate the good electrochemical properties of the synthesized diblock copolymers.

The spatial resolution and the contrast in mechanical property mapping by atomic force microscopy (AFM) modes based on dynamic force-curve acquisition, HarmoniX™(HMX) and Peak-Force-Tapping-QNM™(PFT-QNM) modes, are discussed in terms of contact radius, probe type and imaging parameters. The study is based on model polymer samples including elastomers, thermoplastics and thermoset resins and on contact mechanics considerations to provide a better understanding of the main parameters governing spatial resolution and property contrast in AFM-based nanomechanical mapping. The tip-sample interaction area and volume characterized by the contact radius are the key parameters governing the spatial resolution in adhesion force and elastic modulus images, respectively. The contrast in mechanical properties depends on the proper choice of the probe and on the control of the pixel size and the imaging force. The study also demonstrates that all these parameters are mutually interconnected and may have contradictory influences.

Supported NiO nanocluster catalysts were synthesized by using Ni colloid as a precursor and applied to the aerobic oxidation of 1-phenylethanol. Obtained catalysts were characterized through X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS) and in situ X-ray diffraction (XRD). Activated carbon (AC) supported NiO nanocluster catalyst showed the catalytic activity to the aerobic oxidation of 1-phenylethanol without any additives. Only the AC support allowed the NiO catalyst to be active although the other supports did not. XAFS and in situ XRD revealed that NiO nanocluster was fixed on the supports successfully. XAFS and XPS gave the information about a difference in the local structure, chemical state and electronic state of Ni among the different supports. The obtained catalyst showed the activity more effectively compared to conventional nickel-based catalysts.

Solid acid catalysts are central in our chemical industry and are major players in the valorization of bioresources. However, there is still a need to develop solid acid catalysts with enhanced acid strength and improved, or tunable, physicochemical profile to enhance the efficiency and sustainability of chemical processes. Here, we present a modular approach to tune the acid strength and surface polarity of silica-supported sulfonic acid catalysts based on a versatile copper-catalyzed azide-alkyne cycloaddition (CuAAC)-based anchoring scheme. We precisely take advantage of the CuAAC-formed triazole link to enhance the activity of the grafted sulfonic acids and to pair the acid sites with secondary hydrophobic functions. The beneficial effects of both the triazolium link and the paired hydrophobic site, as well as the optimal positioning of the sulfonic moiety on the triazole ring, are discussed in model esterification reactions. ispartof: Chemistry vol:25 issue:27 pages:6753-6762 ispartof: location:Germany status: Published online

There is a proliferation of autonomous microscale devices, which are increasingly in need of power sources of commensurate form factors. The trade-off between the areal energy and power capabilities of miniature energy storage devices restrict their abilities to meet the requirements of these microscale devices. However, three-dimensional (3D) micro- and nanoarchitectures have the potential to meet the energy requirements of autonomous microscale devices, while retaining the power capabilities of thin-film systems. In this paper, we present a novel full-cell architecture and fabrication strategy for 3D microscale energy storage devices based on template-assisted electrodeposition of three-dimensionally interconnected metallic nanowire network, and its subsequent laser-patterning to form interdigitated nanostructured electrodes. The patterned nanowire networks are functionalized with the polyaniline active electrode material via an electroless deposition procedure. We show that a footprint areal capacitance/energy enhancement of more than 5 times is achieved by just 10 μm-high nanowire networks, in addition to enhanced power capabilities.

The deconstruction of self-assemblies based on proteins and polyelectrolytes (PEs) and the subsequent release of intact proteins requires either a switch from attractive to repulsive mode or particular PE properties (degradability, responsiveness, differential affinity). Here, an interfacial self-assembly made of three charged species, i.e. a strong polyacid complexed with a protein and a weak polybase, is shown to self-reorganize upon pH shift. When the pH takes a value that is one pH unit lower than the pKa of the weak polybase, the two PEs associate, thereby releasing the protein. The disassembly thus relies on associative forces rather than on the alteration of the protein-PE coupling strength. Hence, it allows the release of a protein using two simple PEs. The method is illustrated for lysozyme, which recovered up to half of its initial bioactivity after release. In contrast, a control self-assembled film that could not reorganize only maintained about 21% of the protein bioactivity after disassembly. This versatile approach is valuable for drug delivery devices and biomaterials as it allows the release of large amounts of active protein molecules.

This work presents a simple, fast (20 min treatment), inexpensive, and highly efficient method for synthesizing nitrogen-doped titanium dioxide (N-TiO2) as an enhanced visible light photocatalyst. In this study, N-TiO2 coatings were fabricated by atmospheric pressure dielectric barrier discharge (DBD) at room temperature. The composition and the chemical bonds of the TiO2 and N-TiO2 coatings were characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The results indicate that the nitrogen element has doped the TiO2 lattice, which was further confirmed by Raman spectroscopy and grazing incidence X-ray diffraction (GIXRD). The doping mechanism was investigated using OES to study the plasma properties under different conditions. It suggests that the NH radicals play a key role in doping TiO2. The concentration of nitrogen in the N-TiO2 coatings can be controlled by changing the concentration of NH3 in the plasma or the applied power to adjust the concentration of NH radicals in the plasma. The band gap of N-TiO2 was reduced after NH3/Ar plasma treatment from 3.25 to 3.18 eV. Consequently, the N-TiO2 coating showed enhanced photocatalytic activity under white-light-emitting-diode (LED) irradiation. The photocatalytic degradation rate for the N-TiO2 coating was about 1.4 times higher than that of the undoped TiO2 coating., SCOPUS: ar.j, info:eu-repo/semantics/published

This work reviews an eco-friendly process for producing TiO2 via colloidal aqueous sol–gel synthesis, resulting in crystalline materials without a calcination step. Three types of colloidal aqueous TiO2 are reviewed: the as-synthesized type obtained directly after synthesis, without any specific treatment; the calcined, obtained after a subsequent calcination step; and the hydrothermal, obtained after a specific autoclave treatment. This eco-friendly process is based on the hydrolysis of a Ti precursor in excess of water, followed by the peptization of the precipitated TiO2. Compared to classical TiO2 synthesis, this method results in crystalline TiO2 nanoparticles without any thermal treatment and uses only small amounts of organic chemicals. Depending on the synthesis parameters, the three crystalline phases of TiO2 (anatase, brookite, and rutile) can be obtained. The morphology of the nanoparticles can also be tailored by the synthesis parameters. The most important parameter is the peptizing agent. Indeed, depending on its acidic or basic character and also on its amount, it can modulate the crystallinity and morphology of TiO2. Colloidal aqueous TiO2 photocatalysts are mainly being used in various photocatalytic reactions for organic pollutant degradation. The as-synthesized materials seem to have equivalent photocatalytic efficiency to the photocatalysts post-treated with thermal treatments and the commercial Evonik Aeroxide P25, which is produced by a high-temperature process. Indeed, as-prepared, the TiO2 photocatalysts present a high specific surface area and crystalline phases. Emerging applications are also referenced, such as elaborating catalysts for fuel cells, nanocomposite drug delivery systems, or the inkjet printing of microstructures. Only a few works have explored these new properties, giving a lot of potential avenues for studying this eco-friendly TiO2 synthesis method for innovative implementations.

The hybrid assembling of thermoplastics with thermosets through controlled interdiffusion is an attractive approach towards integrated structural composite bonding. The fracture toughness of the interphase between the high Tg thermoplastic polyetherimide and the RTM6 epoxy is found to be four times higher than the corresponding RTM6 value under specific curing cycle. The origin of this remarkable cracking resistance is elucidated by analyzing the crack path in relationship with the morphology and local elastoplastic and fracture properties of the interphase. The crack is trapped inside a morphological gradient involving a relatively low PEI concentration. Uniaxial compression and nanoindentation tests on homogenous blends exhibit an unexpected softening in this PEI content window. This efficient crack trapping mechanism originates thus from a synergistic coupling between a lower local strength and higher local fracture toughness. This finding opens to many new options for interface toughening beyond the system addressed in this research.

Nickel oxide nanoparticles were synthesized via thermal decomposition of two precursors, the first, a simple nickel malonate and the second, a nickel malonate modified by oleylamine, a surfactant, both having been synthesized by precipitation. While FTIR, TGA and ToF-SIMS were used to characterize the two precursors and to show the presence of oleylamine in the modified precursor, XRD, SEM, TEM and BET were employed to investigate the structure, the morphology and the specific surface area of the decomposition products obtained after pyrolysis. The results showed that the modification of nickel malonate by oleylamine was effective. The XRD results, which showed a cubic structure for the NiO obtained, suggest with SEM an important particle size reduction (at least 54%) when oleylamine was used to modify the nickel malonate precursor. The SEM images also showed a well-defined spherical nanoparticle morphology in both cases, not affected by the presence of oleylamine. The TEM also confirmed the reduction of particle size and their spherical nature but at the same time showed that, in the presence of oleylamine, there was no agglomeration resulting in a more uniform particle size distribution. The specific surface area of the NiO obtained by the oleylamine-modified precursor was 4.7 times larger than that obtained with the regular precursor. This again confirms the particle size reduction.

The present work investigates the grafting of in situ generated 4-pyrrolyphenyldiazonium (Py-PD) on NiTi by two different ways. The first way is the electrografting of Py-PD while the second one is the grafting without electrochemistry at room temperature (spontaneous grafting) or under heating (either conventional heating or induction heating). Both modification routes led to the successful grafting of Py-PD. The hypothesis of a cationic intermediate is proposed for the grafting without electrochemistry since it is thermally activated and the oxidized surface of NiTi is not a reductant. For both modification approaches, the TiO2 surface layer of NiTi has been preserved and the NiTi corrosion resistance improved, an important parameter to preserve/improve the NiTi biocompatibility. The second part of the work is dedicated to the electropolymerization of pyrrole on modified surfaces with the Py-PD as adhesion promoter.

The multiple melting peaks of isothermally crystallized poly(ether ether ketone) were investigated by fast-scanning chip calorimetry over a wide range of heating rates from 500 to 60,000 K s −1 . The analysis of heating rate dependence of melting temperatures revealed that there are two crystal populations with distinct melting kinetics for the samples prepared at different crystallization temperatures, 170 °C ≤ T iso ≤ 270 °C. For each T iso , the two melting temperatures of the metastable crystals without prior reorganization or superheating (i.e. zero-entropy-production melting temperatures) were constantly 20 K and 30 K, respectively, higher than T iso . We first discuss this behavior quantitatively based on the Lauritzen-Hoffman nucleation approach. Finally we conclude that these increases in temperature are linked to the number of stems which construct the secondary surface nuclei. The existence of two crystal populations can be caused by differences in the stability of the crystal or “local” differences in the free energy of the surrounding melt.

We analyze the linear viscoelastic behavior and the strain-rate dependence of nonlinear viscoelastic as well as the ultimate extensional properties of industrially relevant linear polystyrene mixtures (PS). The studied materials comprise different miscible binary mixtures of a well entangled matrix and unentangled diluent resulting in bimodal molar mass distribution (MWD). We also analyze the effect of the diluent weight average molar mass (Mw) by comparison with a mixture having broad but monomodal MWD. We show that the dilution effect on linear rheological properties is in agreement with the theoretical value of unity for the dilution exponent. We further show that the processing window, expressed as the ability of the material to withstand a given load without loss of homogeneity during elongation or ultimate loss of cohesion, is affected differently depending on the diluent Mw and concentration. Finally, we conclude that the existence of strain hardening is not sufficient for complete characterization of extension dominated operations. Our results demonstrate that significant enhancement of strain hardening achieved by adding small-Mw diluents is often accompanied by trade-off with respect to failure behavior of these mixtures. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

The linear viscoelastic properties of entangled hydrolysed poly(n-butyl acrylate) PnBA copolymers, with varying density of functional moieties, i.e., acrylic acid (AA) groups, have been investigated both experimentally and theoretically using small amplitude oscillatory shear and a modified version of the time marching algorithm (TMA). A second, low frequency, plateau, the level of which depends on temperature and AA groups content, is evident in the storage modulus of these copolymers. It indicates that terminal flow, i.e., chain motion at large length scales, is highly suppressed within the experimental timescale. This slow relaxation process is attributed to long lifetime aggregates (sticky junctions) of AA groups. At intermediate frequencies, the dynamic moduli decay with a slope of 0.5 indicative of a Rouse-like relaxation process. This behavior is well captured by the model when constraint release Rouse motion of the strands that are trapped between successive AA junctions or/and trapped entanglements is considered. One new parameter, pst, the probability of a monomer to act as a sticky junction, is introduced in the TMA to account for the influence of the functional AA groups on the chain dynamics. The validation of this simple model is then achieved by comparing experimental and predicted viscoelastic data.

Multi-arm polystyrene stars functionalized with Grubbs-type catalysts in their cores were synthesized and used for the ring-opening metathesis polymerization (ROMP) of cyclopentene. The spatial confinement of the catalytic sites and the nanoscale phase separation between polystyrene and the growing polypentenamer chains lead to a dramatic inhibition of the ROMP termination and chain transfer steps. Consequently, cyclopentene polymerizations proceeded fast and with a high degree of conversion even in air. The Grubbs second generation catalyst was oxidatively inactivated under the same conditions. In contrast to conventional small-molecule catalysts, the ultimate degree of conversion of the cyclopentene monomer and the polydispersity of the product polypentenamer are not affected by the temperature. This indicates that spatial confinement of the catalyst results in a significant change in the activation parameters for the alkene metathesis ring-opening.

A well-defined block copolymer was applied in a semi-organic polymer hybrid-flow battery (pHFB). A 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) containing polymer was utilised as cathode active material. Micellar structures of the active material were achieved by utilising a diblock copolymer composed of a polar poly(TEMPO methacrylate) (PTMA) and an unpolar poly(styrene) (PS) block, which enables the formation of core-corona micelles in organic carbonates. The synthesised PTMA-b-PS was electrochemically investigated and subsequently utilised as catholyte in polymer/Zn pHFBs. The constructed flow batteries feature an excellent cycling stability of 1000 consecutive charge/discharge cycles with 95% retention of initial discharge capacity and a stable voltage range of 2 V. Further, the charging process leads to slight changes in the micellar structure combined with an increased solubility.

Arrays of polymer nanostructures have been widely used in many novel devices and nanofabrication methods. The glass transition temperature, which is a key parameter influencing the long-term stability of polymer nanostructures, has not yet been systematically studied and well understood. Here we study this technological and fundamental issue with polymers of different values of molar mass M confined in nanocylinders of a varying diameter D. The glass transition temperature Tg loses its dependence on the molar mass for D ≲ 100 nm, a range in which the relative depression of Tg varies as D(-0.44). For higher cylinder diameters, Tg progressively recovers its dependence on the molar mass. This is quantitatively reproduced by a model based on an equilibrium interfacial excess of free volume, which needs to be created unless provided by the chain ends. Our findings suggest that the structural perturbations during nanofabrication may strongly affect the long-term stability of arrays of polymer nanostructures.

International audience; Solid polymer electrolytes are prepared by mixing various amounts of lithium bis(trifluoromethanesulfonyl)imide with poly(vinylidene fluoride‐co‐vinyl dimethyl phosphonate) statistical copolymers with different compositions. Such copolymers are obtained by conventional radical copolymerization of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by peroxides. A morphological study of the obtained solid polymer electrolytes (SPEs) shows that only samples prepared from the copolymer with the lower amount of VDMP (16 mol%) result in the formation of homogeneous electrolytes while aggregates of lithium salts are observed for the other copolymers. The best ionic conductivity values are accordingly observed for the copolymers with the lower VDMP amount and are reaching 5 × 10−3 mS cm−1 at 100 °C. The dependence of the ionic conductivity versus temperature suggests that the ionic conductivity is controlled by the motion of polymer segments. Indeed, the ionic conductivity can be increased by adding a small amount of trimethylphosphate plasticizer and can reach 1.9 × 10−2 mS cm−1 at 20 °C. Finally, the prepared SPEs exhibit a high electrochemical stability and a good resistance to flame because of the presence of fire‐retardant phosphate groups in their structure.

The coming ban on substances of high environmental concern used to provide water repellency to fabrics creates new challenges for the textile industry. Here we show that the design of the texture of woven fabrics is an important parameter to play with in order to achieve higher water repellency, which could help relax the limitations set by more environmentally-friendly coating materials. A mathematical framework is first developed to describe the roughness of woven fabrics and its relationship with water repellency, and metrological aspects of the characterization of the roughness of such fabrics by profilometry are discussed. The roughness of eight different fabric surfaces is then characterized, together with their water repellency after having been coated by wax-based, silicone-based or perfluorobutyl-based commercial polymer formulations. Fabrics of measured roughness lower than a critical value are in a partially-wet state with a substantial pinning of the droplets on their surface and an absence of roll-off whatever the type of hydrophobic coating. Above this critical value, the fabrics enter the superficially-wet state, in which the contact angle becomes controlled by the amount of air trapped in the texture. In this regime, the roll-off angle strongly depends on the wetting hysteresis of the coating material. Keywords: Woven fabrics, Roughness, Water repellency, Water roll-off angle, Water contact angle

In this paper, laboratory synthesized Phenol-paraPhenyleneDiAmine (P-pPDA) benzoxazine containing different amounts of B-trimesityl-N-triphenylborazine was applied by spin coating on aluminum and thermally cured. The addition of the borazine derivative (borazine 1) does not appear to modify the curing characteristics of the P-pPDA matrix itself as shown by FTIR, DSC and DEA analyses; however, some interactions - chemical and/or physical (co-crystallization) – between P-pPDA and borazine 1 cannot be excluded. The microstructure of the composites is characterized by a two phase system consisting of a dispersion of nanosized (10–20 nm) clusters for the lowest borazine 1 concentration (0.5 wt%), evolving towards bigger (100–200 nm), agglomerated clusters for higher borazine 1 concentrations (3 wt%) and finally, continuous, dendritic structures within the P-pPDA matrix for the highest borazine 1 concentration (10 wt%). The benzoxazine composite coating containing 0.5 wt% trimesitylborazine derivative showed a largely increased and durable ability to protect the aluminum substrate. It is shown that a highly capacitive behavior and durable barrier properties can be obtained for P-pPDA coatings containing such a low amount of borazine derivative homogeneously dispersed in the benzoxazine matrix. For concentrations of 3 wt%, as agglomeration took place and dendrites appeared for the highest concentration of borazine derivative (10 wt%), the corrosion resistance decreased with time.

We reported an efficient way of preparing large and dense ferromagnetic arrays of vertically-aligned Ni nanotubes (NTs). The synthesis method allowed then for a direct, effective and controllable thermal conversion of the as-prepared Ni NTs into heterostructured Ni/NiO NTs, without compromising the nanostructures' verticality to the substrate and their initial tubular integrity. Next, we demonstrated the ability to tune the dipolar interaction field (DIF) in this array of one-dimensional (1D) Ni/NiO heterostructures, just by slightly changing the thickness of the antiferromagnetic NiO layer. Furthermore, the proposed fabrication method assures full compatibility with the standard Si processing, providing thus a direct pathway towards large-scale integrability and manufacturing of a new generation of magnetic devices relying on dense arrays of vertical 1D magnetic nanostructures.

Small organic materials are generally plagued by their high solubility in battery electrolytes. Finding approaches to suppress solubilization while not penalizing gravimetric capacity remains a challenge. Here we propose the concept of a hydrogen bond stabilized organic battery framework as a viable solution. This is illustrated for 2,5-diamino-1,4-benzoquinone (DABQ), an electrically neutral and low mass organic chemical, yet with unusual thermal stability and low solubility in battery electrolytes. These properties are shown to arise from hydrogen bond molecular crystal stabilization, confirmed by a suite of techniques including X-ray diffraction and infrared spectroscopy. We also establish a quantitative correlation between the electrolyte solvent polarity, molecular structure of the electrolyte and DABQ solubility – then correlate these to the cycling stability. Notably, DABQ displays a highly reversible (above 99%) sequential 2-electron electrochemical activity in the solid phase, a process rarely observed for similar small molecular battery chemistries. Taken together, these results reveal a potential new strategy towards stable and practical organic battery chemistries through intramolecular hydrogen-bonding crystal stabilization.

The development of multifunctional surfaces is of general interest for the fabrication of biomedical, catalytic, microfluidic or biosensing devices. Herein, we report on the preparation of copolymer layers immobilized on gold surface and showing both free thiol and amino groups. These layers are produced by aminolysis of a thiolactone-based copolymer in the presence of a diamine, according to a one-step procedure. The free thiol and amino groups present in the modified copolymer layers can be successfully functionalized with respectively thiolated and carboxylic derivatives, in order to produce bifunctionalized surfaces. In addition, we show that the grafted thiolated derivative can be released by cleavage of the disulfide bond under mild reducing conditions. On the other hand, a side cross-linking reaction occurring during the grafting process and resulting in the formation of copolymer aggregates on the metal surface is evidenced. The methodology developed for the preparation of these bifunctionalized redox-responsive layers should be advantageously used to produce bioactive surfaces with drug loading/release properties.

Hybrid nanobiointerfaces were designed as an original contribution to the challenge of synthesizing nanostructured biomaterials integrating a set of cell fate-determining cues, originally provided to cells by the extracellular matrix (ECM). The produced biointerfaces consist of a stiff framework of intersected polypyrrole (PPy) nanotubes supporting a soft multilayer composed of ECM-derived biomacromolecules: collagen (Col) and hyaluronic acid (HA). PPy frameworks with highly tunable characteristics were synthesized through chemical oxidative polymerization of pyrrole monomers, templated within track-etched polycarbonate (PC) membranes featuring a network of intersected nanopores. PPy interfaces with a porosity of 80%, composed of nanotubes with an average diameter ranging from 40 to 300 nm, intersecting at an angle of 90°, were shown to be self-supported. These rigid PPy nanostructured interfaces were functionalized with a self-assembling (HA/Col) multilayer deposited via a layer-by-layer process. Biofunctionalized and unmodified PPy frameworks were both shown to promote sustained cell adhesion, therefore demonstrating the cytocompatibility of the engineered matrices. Such nanobiointerfaces, combining a mechanically-stable framework of tunable dimensions with a soft biopolymeric multilayer of highly versatile nature, pave the way towards cell-instructive biomaterials able to gather a wide range of cues guiding cell behavior. The developed self-supported structures could be used as a coating or as membranes bridging different tissues.

We report on a facile, versatile, and environmentally friendly method to prepare superhydrophobic fabrics by a simple dip-coating method in water-based suspensions and emulsions. All the materials used are fluorine-free and commercially available at a large scale. The method can be easily integrated into standard textile industrial processes and has a strong potential for the mass production of environmentally friendly superwater-repellent fabrics. The produced fabrics show good resistance to machine washing and acidic or alkaline treatments. In addition, it is shown that superhydrophobicity can be quantitatively predicted based on the combination of the roughness of the fabric and of the fiber coating.

International audience; A poly(vinylidene fluoride-co-(2-oxo-1,3-dioxolan-4-yl)methyl 2-(trifluoromethyl)acrylate) random copolymer, poly(VDF-co-MAF-cyCB), with a MAF-cyCB weight fraction of 59% was synthesized via free radical copolymerization of VDF and MAF-cyCB, which is a methacrylate bearing cyclocarbonate side-chain. This copolymer showed nano-structured morphology, where crystalline PVDF-rich domains co-existed with amorphous poly(VDF-co-MAF-cyCB) segments. Solid polymer electrolytes were further obtained by loading the poly(VDF-co-MAF-cyCB) copolymer with various amounts of LiClO4. The added lithium salt was dissolved in the poly(VDF-co-MAF-cyCB) amorphous phase, which allowed the formation of an ionic conducting phase exhibiting ionic conductivity values as high as 2 × 10−4 S cm−1 at room temperature for an optimum cyCB/Li+ molar ratio of 5. The addition of LiClO4 up to the optimum cyCB/Li+ molar ratio of 5 also increased the phase separation between the crystalline and amorphous phases, the mechanical properties of the material (up to 107 at 102 rad s−1) and the ionic conductivity (>10−3 S cm−1 at 80 °C). Furthermore, an electrochemical stability window from 1.4 to 4.9 V vs. Li/Li+ and relatively high values for the measured lithium ions transference numbers (0.68 at 40 °C) were observed, making the investigated system a promising candidate for next generation solid polymer electrolytes.

Commensal skin bacteria such as Staphylococcus epidermidis are currently being considered as possible components in skin-care and skin-health products. However, considering the potentially adverse effects of commensal skin bacteria if left free to proliferate, it is crucial to develop methodologies that are capable of maintaining bacteria viability while controlling their proliferation. Here, we encapsulate S. epidermidis in shells of increasing thickness using layer-by-layer assembly, with either a pair of synthetic polyelectrolytes or a pair of oppositely charged polysaccharides. We study the viability of the cells and their delay of growth depending on the composition of the shell, its thickness, the charge of the last deposited layer, and the degree of aggregation of the bacteria which is varied using different coating procedures-among which is a new scalable process that easily leads to large amounts of nonaggregated bacteria. We demonstrate that the growth of bacteria is not controlled by the mechanical properties of the shell but by the bacteriostatic effect of the polyelectrolyte complex, which depends on the shell thickness and charge of its outmost layer, and involves the diffusion of unpaired amine sites through the shell. The lag times of growth are sufficient to prevent proliferation for daily topical applications.