Electrolyte additives have been widely used to address critical issues in current metal (ion) battery technologies. While their functions as solid electrolyte interface forming agents are reasonably well‐understood, their interactions in the liquid electrolyte environment remain rather elusive. This lack of knowledge represents a significant bottleneck that hinders the development of improved electrolyte systems. Here, the key role of additives in promoting cation (e.g., Li+) desolvation is unraveled. In particular, nitrate anions (NO3−) are found to incorporate into the solvation shells, change the local environment of cations (e.g., Li+) as well as their coordination in the electrolytes. The combination of these effects leads to effective Li+ desolvation and enhanced battery performance. Remarkably, the inexpensive NaNO3 can successfully substitute the widely used LiNO3 offering superior long‐term stability of Li+ (de‐)intercalation at the graphite anode and suppressed polysulfide shuttle effect at the sulfur cathode, while enhancing the performance of lithium–sulfur full batteries (initial capacity of 1153 mAh g−1 at 0.25C) with Coulombic efficiency of ≈100% over 300 cycles. This work provides important new insights into the unexplored effects of additives and paves the way to developing improved electrolytes for electrochemical energy storage applications.
A fast and living ring-opening polymerization (ROP) of ω-pentadecalactone (PDL), a representative monomer of macrolactones, was achieved using a primary alcohol as the initiator and t-BuP4 or t-octP4 as the catalyst.
Poly(macrolactones) (PMLs) can be considered as biodegradable alternatives of polyethylene; however, controlling the ring-opening polymerization (ROP) of macrolactone (ML) monomers remains a challenge due to their low ring strain. To overcome this problem, phosphazene (t-BuP 4), a strong superbase, has to be used as catalyst. Unfortunately, the one-pot sequential block copolymerization of MLs with small lactones (SLs) is impossible since the high basicity of t-BuP 4 promotes both intra-and intermolecular transesterification reactions, thus leading to random copolymers. By using ROP and the "catalyst-switch" strategy [benzyl alcohol, t-BuP 4 /neutralization with diphenyl phosphate/(t-BuP 2)], we were able to synthesize different well-defined PML-b-PSL block copolymers (MLs: dodecalactone, ω-pentadecalactone, and ωhexadecalactone; SLs: δ-valerolactone and ε-caprolactone). The thermal properties and the phase behavior of these block copolymers were studied by differential scanning calorimetry and X-ray diffraction spectroscopy. This study shows that the thermal properties and phase behavior of PMLs-b-PSLs are largely influenced by the PMLs block if PMLs components constitute the majority of the block copolymers.
Solvent-solvent and solvent-anion pairings in battery electrolytes have been identified for the first time by nuclear magnetic resonance spectroscopy. These hitherto unknown interactions are enabled by the hydrogen bonding induced by the strong Lewis acid Li + , and exist between the electron-deficient hydrogen (𝜹 + H) present in the solvent molecules and either other solvent molecules or negatively-charged anions. Complementary with the well-established strong but short-ranged Coulombic interactions between cation and solvent molecules, such weaker but longer-ranged hydrogen-bonding casts the formation of an extended liquid structure in electrolytes that is influenced by their components (solvents, additives, salts, and concentration), which in turn dictates the ion transport within bulk electrolytes and across the electrolyte-electrode interfaces. The discovery of this new inter-component force completes the picture of how electrolyte components interact and arrange themselves, sets the foundation to design better electrolytes on the fundamental level, and probes battery performances.
Fluorescent drug delivery systems have received increasing attention in cancer therapy because they combine drug delivery and bioimaging into a single platform. For example, polymers with aggregation-induced emission (AIE) fluorophores, such as tetraphenylethylene (TPE), have emerged as an elegant choice for drug delivery/bioimaging applications. In this work, we report one-pot sequential organocatalytic ring-opening polymerization of ε-caprolactone (CL) and ethylene oxide (EO) using TPE-(OH) 2 as a difunctional initiator, in the presence of a t-BuP 2 /TEB Lewis pair (catalyst), in THF at room temperature. Two well-defined triblock copolymers with inverse block sequences, TPE-(PCL-b-PEO) 2 and TPE-(PEO-b-PCL) 2 , were synthesized by altering the sequential addition of CL and EO. The physicochemical properties, including hydrodynamic diameter, morphology, and AIE properties of the synthesized amphiphilic triblock copolymers were investigated in aqueous media. The block copolymer micelles were loaded with anticancer drugs doxorubicin and curcumin to serve as drug delivery vehicles. In vitro studies revealed the accelerated drug release at lower pH (5.5), which mimics the tumor microenvironment, different from the physiological pH (7.4). In vitro cytotoxicity studies demonstrated that the neat block copolymer micelles are biocompatible, while drug-loaded micelles exhibited a significant cytotoxic effect in cancer cells. Cellular uptake, examined by confocal laser scanning microscopy, showed that the block copolymer micelles were rapidly internalized by the cells with simultaneous emission of TPE fluorophore. These results suggest that these triblock copolymers can be utilized for intracellular bioimaging.
Multicrystalline blockp olymers having three or more crystalline segments are essential materials for the advancement of physics in the field of crystallinity.T he challenging synthesis of multicrystalline polymers has resulted in only al imited number of tricrystalline terpolymers having been reported to date.Wereport, for the first time,the synthesis, atetracrystalline tetrablockq uarterpolymer,b yc ombining polyhomologation, ring-opening polymerization, and an organic/ metal "catalyst switch"s trategy. 1 HNMR spectroscopya nd gel-permeation chromatography confirmed the formation of the tetrablockq uarterpolymer,w hile differential scanning calorimetry,X -ray diffraction, and wide-line separation solidstate NMR spectroscopyrevealed the existence of four different crystalline domains.Supportinginformation and the ORCID identification numbers for some of the authors of this article can be found under: https://doi.Figure 6. X-ray diffractograms of PE-OH-2 (black), PE-b-PEO-2 (red), PE-b-PEO-b-PCL-2 (blue), and PE-b-PEO-b-PCL-b-PLLA-2 (green).
Living anionic polymerization will soon celebrate 70 years of existence. This living polymerization is considered the mother of all living and controlled/living polymerizations since it paved the way for their discovery. It provides methodologies for synthesizing polymers with absolute control of the essential parameters that affect polymer properties, including molecular weight, molecular weight distribution, composition and microstructure, chain-end/in-chain functionality, and architecture. This precise control of living anionic polymerization generated tremendous fundamental and industrial research activities, developing numerous important commodity and specialty polymers. In this Perspective, we present the high importance of living anionic polymerization of vinyl monomers by providing some examples of its significant achievements, presenting its current status, giving several insights into where it is going (Quo Vadis) and what the future holds for this powerful synthetic method. Furthermore, we attempt to explore its advantages and disadvantages compared to controlled/living radical polymerizations, the main competitors of living carbanionic polymerization.
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