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High sulfur loading is essential for achieving high energy density lithium-sulfur (Li-S) batteries. However, serious issues such as low sulfur utilization, poor cycling stability, and sluggish rate performance have been exposed when increasing the sulfur loading for freestanding cathodes. To solve these problems, the adsorption/catalytic ability of high-sulfur-loading cathode toward polysulfides must be improved. Herein, based on excellent properties of cationic MOFs, we proposed that Cu-Mo bimetallic nanoparticles embedded in multifunctional freestanding nitrogen-doped porous carbon nanofibers (Cu-Mo@NPCN) with efficient catalytic sites could be prepared by facile MoO

Poly(vinylidenefluoride-trifluoroethylene)-based (P(VDF-TrFE)-based) terpolymers represent a new class of electroactive polymer materials that are relaxor-ferroelectric (RF) polymers and that offer unique and attractive property combinations in comparison with conventional ferroelectric polymers. The RF state is achieved by introducing a fluorine-containing termonomer as a “defect” into the ferroelectric P(VDF-TrFE) copolymer, which reduces the interaction between the VDF/TrFE dipoles. The resulting terpolymer exhibits a low Curie transition temperature and small remanent and coercive fields yielding a slim hysteresis loop that is typical for RF materials. Though the macroscopic behavior is similar to RF ceramics, the mechanisms of relaxor ferroelectricity in semi-crystalline polymers are different and not fully understood yet. Structure-property relationships play an important role in RF terpolymers, as they govern the final RF properties. Hence, a review of important characteristics, previous studies and relevant developments of P(VDF-TrFE)-based terfluoropolymers with either chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE) as the termonomer is deemed useful. The role of the termonomer and of its composition, as well as the effects of the processing conditions on the semi-crystalline structure which in turn affects the final RF properties are discussed in detail. In addition, the presence of noteworthy transition(s) in the mid-temperature range and the influence of preparation conditions on those transitions are reviewed. A better understanding of the fundamental aspects affecting the semi-crystalline structures will help to elucidate the nature of RF activity in VDF-based terpolymers and also help to further improve their applications-relevant electroactive properties. ispartof: FERROELECTRICS vol:586 issue:1 pages:60-81 status: published

ispartof: Physica Status Solidi A-Applications And Materials Science vol:219 issue:23 status: accepted

The behavior of polymers confined in ultrathin films (thickness < 200 nm) can sensitively differ from that observed in macroscopic samples. Based on the simple arguments of finite size and interfacial effects, film thickness, and surface interactions should be sufficient to univocally determine the deviation from bulk behavior. However, recent models suggest that a third key parameter, namely, the interfacial free volume, should also be considered. We describe a novel methodology that quantifies the volume available for structural relaxation at the interface between a thin polymer layer and its supporting substrate. Experiments performed at different annealing conditions verified that the shift in glass transition temperature, measured in thin films upon confinement, is proportional to the degree of adsorption and, thus, to the interfacial free volume.

Confined at the nanoscale level, polymers crystallize much slower than in bulk, and in some cases, the formation of ordered structure is inhibited within extremely long experimental time scales. Here, we report on the thickness dependence of the conversion rate of the amorphous fraction of ultrathin films of poly(ethylene terephthalate) during isothermal cold crystallization. We present a new analytical method assessing the impact of irreversible chain adsorption and permitting to disentangle finite size and interfacial effects. From the μm range down to a few tens of nm, we observed an increase in crystallization time scaling with the inverse of the film thickness, which is a fingerprint of finite size effects. Films thinner than ∼20 nm did not crystallize, even after prolonged annealing in the temperature range where the crystallization rate reaches its maximum value. Noticing that this threshold corresponds to the total thickness of the layer irreversibly adsorbed within our investigation time, we explain these findings considering that chain adsorption increases the entropic barrier required for the formation of crystalline structures.

Dynamically controlling cell-material interactions has a strong potential for advancing many cell-based technologies, including cell detection and cell sorting systems. To this end, fundamental studies that provide insights into how cells respond biologically to physico-chemical cues are necessary. Studies show that biological responses, such as cytoskeletal reorganization alter the overall viscoelastic properties of cells. Here, we monitored, in real time, and non-invasively, the evolution of the viscoelastic properties of yeast cells as a function of medium ionic strength (IS). Measurements were performed on SiO2-coated sensor surfaces using the quartz crystal microbalance with dissipation monitoring (QCM-D). Our results indicate that, for every adhesion phase, the cell stiffness decreases with increasing IS. This trend was consistent across the various cell concentrations studied. In terms of cell-substrate interactions, we show that a high IS promotes cell adhesion for all cell concentrations, including ultra-low concentrations. Our results also show that while the adhesion signal decreases with cell concentration for each IS, only temporal and close to noise-level adhesion signals were measured in ion-free medium irrespective of the cell concentration. We also show that cell adhesion rates are higher in physiological ionic strengths compared to cells in higher ionic strengths. Finally, from a cell detection perspective, the results reveal that for very low cell concentrations, large signal enhancements can be achieved by measuring the same concentration in a higher ionic strength. This result also applies for measurements on gold surfaces; thus, we suggest ionic tuning as a strategy for promoting trace-level cell detection in biosensors and cell sorting applications. ispartof: Physics in Medicine vol:14 status: Published online