Leaching kinetics of fluorine during the aluminum removal from spent Li-ion battery cathode materials

The high content of aluminum (Al) impurity in the recycled cathode powder seriously affects the extraction efficiency of Nickel, Cobalt, Manganese, and Lithium resources and the actual commercial value of recycled materials, so Al removal is crucially important to conform to the industrial standard of spent Li-ion battery cathode materials. In this work, we systematically investigated the leaching process and optimum conditions associated with Al removal from the cathode powder materials collected in a wet cathode-powder peeling and recycling production line of spent Li-ion batteries (LIBs). Moreover, we specifically studied the leaching of fluorine (F) synergistically happened along with the removal process of Al, which was not concerned about in other studies, but one of the key factors affecting pollution prevention in the recovery process. The mechanism of the whole process including the leaching of Al and F from the cathode powder was indicated by using NMR, FTIR, and XPS, and a defluoridation process was preliminarily investigated in this study. The leaching kinetics of Al could be successfully described by the shrinking core model, controlled by the diffusion process and the activation energy was 11.14 kJ/mol. While, the leaching of F was attributed to the dissolution of LiPF6 and decomposition of PVDF, and the kinetics associated was described by Avrami model. The interaction of Al and F is advantageous to realize the defluoridation to some degree. It is expected that our investigation will provide theoretical support for the large-scale recycling of spent LIBs.

Exploring the Influence of Spacers in EDTA-β-Cyclodextrin Dendrimers: Physicochemical Properties and In Vitro Biological Behavior

The synthesis of a new family of ethylenediaminetetraacetic acid (EDTA) core dimers and G0 dendrimers end-capped with two and four β-cyclodextrin (βCD) moieties was performed by click-chemistry conjugation, varying the spacers attached to the core. The structure analyses were achieved in DMSO-d6 and the self-inclusion process was studied in D2O by 1H-NMR spectroscopy for all platforms. It was demonstrated that the interaction with adamantane carboxylic acid (AdCOOH) results in a guest-induced shift of the self-inclusion effect, demonstrating the full host ability of the βCD units in these new platforms without any influence of the spacer. The results of the quantitative size and water solubility measurements demonstrated the equivalence between the novel EDTA-βCD platforms and the classical PAMAM-βCD dendrimer. Finally, we determined the toxicity for all EDTA-βCD platforms in four different cell lines: two human breast cancer cells (MCF-7 and MDA-MB-231), human cervical adenocarcinoma cancer cells (HeLa), and human lung adenocarcinoma cells (SK-LU-1). The new EDTA-βCD carriers did not present any cytotoxicity in the tested cell lines, which showed that these new classes of platforms are promising candidates for drug delivery.

A Self-Forming Hydrogel from a Bactericidal Copolymer: Synthesis, Characterization, Biological Evaluations and Perspective Applications

Objects touched by patients and healthcare workers in hospitals may harbor pathogens, including multi-drug resistant (MDR) staphylococci, enterococci (VRE), Escherichia coli, Acinetobacter, and Pseudomonas species. Medical devices contaminated by these pathogens may also act as a source of severe and difficult-to-treat human infections, thus becoming a critical public health concern requiring urgent resolutions. To this end, we recently reported the bactericidal effects of a cationic copolymer (CP1). Here, aiming at developing a bactericidal formulation possibly to be used either for surfaces disinfection or to treat skin infections, CP1 was formulated as a hydrogel (CP1_1.1-Hgel). Importantly, even if not cross-linked, CP1 formed the gel upon simple dispersion in water, without requiring gelling agents or other additives which could be skin-incompatible or interfere with CP1 bactericidal effects in possible future topical applications. CP1_1.1-Hgel was characterized by attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) and UV-Vis spectroscopy, as well as optic and scanning electron microscopy (OM and SEM) to investigate its chemical structure and morphology. Its stability was assessed by monitoring its inversion properties over time at room temperature, while its mechanical characteristics were assessed by rheological experiments. Dose-dependent cytotoxicity studies performed on human fibroblasts for 24 h with gel samples obtained by diluting CP_1.1-Hgel at properly selected concentrations established that the 3D network formation did not significantly affect the cytotoxic profile of CP1. Also, microbiologic investigations carried out on two-fold serial dilutions of CP1-gel confirmed the minimum inhibitory concentrations (MICs) previously reported for the not formulated CP1.Selectivity indices values up to 12 were estimated by the values of LD₅₀ and MICs determined here on gel samples.

Semi-Fluorinated Di and Triblock Copolymer Nano-Objects Prepared via RAFT Alcoholic Dispersion Polymerization (PISA)

A set of well-defined amphiphilic, semi-fluorinated di and triblock copolymers were synthesized via polymerization-induced self-assembly (PISA) under alcoholic dispersion polymerization conditions. This study investigates the influence of the length, nature and position of the solvophobic semi-fluorinated block. A poly(N,N-dimethylaminoethyl methacrylate) was used as the stabilizing block to prepare the di and tri block copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) controlled dispersion polymerization at 70 °C in ethanol. Benzylmethacrylate (BzMA) and semi-fluorinated methacrylates and acrylates with 7 (heptafluorobutyl methacrylate (HFBMA)), 13 (heneicosafluorododecyl methacrylate (HCFDDMA)) and 21 (tridecafluorooctyl acrylate (TDFOA)) fluorine atoms were used as monomers for the core-forming blocks. The RAFT polymerization of these semi-fluorinated monomers was monitored by SEC and 1H NMR. The evolution of the self-assembled morphologies was investigated by transmission electron microscopy (TEM). The results demonstrate that the order of the blocks and the number of fluorine atoms influence the microphase segregation of the core-forming blocks and the final morphology of the nano-objects.

Surfactant-free emulsion polymerization of vinylidene fluoride mediated by RAFT/MADIX reactive poly(ethylene glycol) polymer chains

Vinylidene fluoride (VDF) emulsion polymerization is conducted in the presence of xanthate-end functionalized poly(ethylene glycol)s leading to stable PVDF latexes.

First Class of Phosphorus Dendritic Compounds Containing β-Cyclodextrin Units in the Periphery Prepared by CuAAC

A new class of phosphorus dendritic compounds (PDCs) having a cyclotriphosphazene (P₃N₃) core and decorated with six β-cyclodextrin (βCD) units, named P₃N₃-[O-C₆H₄-O-(CH₂)_n-βCD]₆, where n = 3 or 4 was designed, and the synthesis was performed using copper (I) catalyzed alkyne-azide cycloaddition (CuAAC). To obtain the complete substitution of the P₃N₃, two linkers consisting of an aromatic ring and an aliphatic chain of two different lengths were assessed. We found that, with both linkers, the total modification of the periphery was achieved. The two new obtained dendritic compounds presented a considerably high water solubility (>1 g/mL). The compounds comprised in this new class of PDCs are potential drug carrier candidates, since the conjugation of the βCD units to the P₃N₃ core through the primary face will not only serve as surface cover but, also, provide them the faculty to encapsulate various drugs inside the βCDs cavities.

Phosphorus-Containing Fluoropolymers: State of the Art and Applications

Several strategies to synthesize fluorinated (co)polymers containing phosphorus groups and their applications are reviewed. First, original fluoromonomers bearing phosphorus atoms are supplied from relevant routes. They may possess fluorinated atoms linked to the ethylenic carbon atoms with different structures, such as F₂C═CF- or H₂C═C(CF₃)- and a phosphonated ω-function adjacent to an aliphatic or aromatic linker, while other monomers display a difluoromethylene dialkylphosphonate end group such as -CF₂-P(O)(OR)₂. Then, fluorinated copolymers were obtained according to various pathways: (i) by radical homopolymerization of monomers containing both fluorine and phosphorus atoms, (ii) by direct radical copolymerization of fluoromonomers and phosphorus-based monomers, or (iii) by chemical modification of fluorinated copolymers with phosphorus-based reactants. Conventional radical and controlled (or reversible deactivation radical polymerization, RDRP) copolymerization have also been explored. As for the chemical change of halogenated polymers, either conventional organic reactions (e.g., Arbuzov reaction from a chlorine, iodine, or bromine atom) or radiation grafting with specific monomers led to graft copolymers composed of a fluorinated backbone and phosphonated grafts. This second part also details aliphatic and aromatic fluorophosphorous copolymers in which dialkylphosphonates or phosphonic acids are reported. Finally, since fluorine and phosphorus atoms bring complementary relevant properties (low refractive index and dielectric constants, chemical inertness, high electrochemical, soils, and heat resistances, electroattractivity from fluorine atoms and high acidity, complexation, anticorrosion, flame retardant, and biomedical properties from phosphorus ones), synergetic characteristics have been targeted. These properties allow such fluoro-phosphorus (co)polymers to be used as novel materials involved in various applications such as polymer exchange membranes for fuel cells, self-etching adhesives for dental materials, adhesion promoters, flame retardants, polymer blends, and anticorrosive coatings.

π-Stacking Interactions of Graphene-Coated Cobalt Magnetic Nanoparticles with Pyrene-Tagged Dendritic Poly(Vinylidene Fluoride)

This study investigates the non-covalent coating of cobalt magnetic nanoparticles (MNPs) involving a graphene surface with pyrene-tagged dendritic poly(vinylidene fluoride) (PVDF). Dendrimers bearing a pyrene moiety were selected to play the role of spacers between the graphene surface of the MNPs and the PVDF chains, the pyrene unit being expected to interact with the surface of the MNPs. The pyrene-tagged dendritic spacer 11 decorated with ten acetylenic units was prepared and fully characterized. Azido-functionalized PVDF chains were then grafted onto each branch of the dendrimer using Huisgen's [3+2] cycloaddition reaction. Next, the association of the resulting pyrene-tagged dendritic PVDF 13 with commercially available Co/C MNPs by π-stacking interactions was studied by fluorescence spectroscopy. Evaluated were the stability of the π-stacking interactions when the temperature increased and the reversibility of the process when the temperature decreased. Also, hybrid MNPs were prepared from pyrene-tagged dendrimers decorated either with acetylenic functions (11) or with PVDF branches (13), and they were characterized by transmission electron microscopy and comparative elemental analysis was carried out with naked MNPs.

Fluoropolymers: The Right Material for the Right Applications

An overview on the synthesis, properties, and applications of fluoropolymers (PFs) is presented. First, a non-exhaustive summary on the homopolymers from conventional radical polymerization of fluoromonomers is proposed. FPs are interesting materials thanks to their outstanding properties such as thermal, oxidative and chemical resistances, low dissipation factor, refractive index, permittivity, and water absorptivity, as well as excellent durability and weatherability. Various strategies of synthesis are proposed, especially on recent studies on radical (co)polymerization of fluoroalkenes, just like their properties and applications ranging from coatings and energy-related materials (e.g. fuel cell membranes, components for lithium ion batteries, electroactive devices, and photovoltaics) to original fluorinated elastomers, surfactants, thermoplastic elastomers, thermostables, and optical devices.

Polymerization-induced self-assembly of PVAc-b-PVDF block copolymers via RAFT dispersion polymerization of vinylidene fluoride in dimethyl carbonate

This article reports the results of the study of the RAFT dispersion polymerization of VDF in dimethyl carbonate using PVAc macroCTAs. The morphology of the resulting crystalline polymer aggregates is likely governed by crystallization of the PVDF.

An amphiphilic poly(vinylidene fluoride)-b-poly(vinyl alcohol) block copolymer: synthesis and self-assembly in water

This study is the first report of the synthesis and self-assembly in water of an amphiphilic PVDF-b-PVA block copolymer.

Self-assembly of poly(vinylidene fluoride)-block-poly(2-(dimethylamino)ethylmethacrylate) block copolymers prepared by CuAAC click coupling

Self-assembly of PDMAEMA-b-PVDF block copolymers.