Electron Beam Processing as a Promising Tool to Decontaminate Polymers Containing Brominated Flame Retardants.

Electron Beam (EB) irradiation was utilized to decontaminate model systems of industrial polymers that contain a brominated flame retardant (BFR). Acrylonitrile-butadiene-styrene (ABS) and Polycarbonate (PC) are two types of polymers commonly found in Waste Electrical and Electronic Equipment (WEEE). In this study, these polymers were exposed to EB irradiation to degrade DecaBromoDiphenylEther (DBDE), one of the most toxic BFRs. Fourier-transform infrared spectroscopy analysis demonstrated an 87% degradation rate of DBDE for the ABS-DBDE system and 91% for the PC-DBDE system following an 1800 kGy irradiation dose. Thermal analysis using Differential Scanning Calorimetry revealed the presence of crosslinking in ABS and a minor reduction in the glass transition temperature of PC after EB processing. Polymers exhibited thermal stability after photolysis, as indicated by thermogravimetric analysis. In summary, EB irradiation had no impact on the overall thermal properties of both polymers. High-resolution mass spectrometry analysis has confirmed the debromination of both ABS-DBDE and PC-DBDE systems. Therefore, the results obtained are promising and could offer an alternative approach for removing bromine and other additives from plastic E-waste.

New Insight into Nanoscale Identification of the Polar Axis Direction in Organic Ferroelectric Films.

Ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)] thin films have been deposited by spin-coating onto the Bi0.5Na0.5TiO3(BNT)/LNO/SiO2/Si heterostructure. The copolymer microstructure investigated by using grazing-incidence wide-angle X-ray diffraction (GIWAXD) and deduced from the (200)/(110) reflections demonstrates that the b-axis in the P(VDF-co-TrFE) orthorhombic unit cell is either in the plane or out of the plane, depending on the face-on or on the two types of edge-on (called I and II) lamellar structures locally identified by atomic force microscopy (AFM). For edge-on I lamellae regions, the electroactivity (dzzeff ∼ -50.3 pm/V) is found to be twice as high as that measured for both edge-on II or face-on crystalline domains, as probed by piezoresponse force microscopy (PFM). This result is directly correlated to the direction of the ferroelectric polarization vector in the P(VDF-co-TrFE) orthorhombic cell: larger nanoscale piezoactivity is related to the b-axis which lies along the normal to the substrate plane in the case of the edge-on I domains. Here, the ability to thoroughly gain access to the as-grown polar axis direction within the edge-on crystal lamellae of the ferroelectric organic layers is evidenced by combining the nanometric resolution of the PFM technique with a statistical approach based on its spectroscopic tool. By the gathering of information at the nanoscale, two orientations for the polar b-axis are identified in edge-on lamellar structures. These findings contribute to a better understanding of the structure-property relationships in P(VDF-co-TrFE) films, which is a key issue for the design of future advanced organic electronic devices.

Cooperative Synthesis of Raspberry-Like Covalent Organic Framework-Polymer Particles with a Radial Single-Crystal Grain Orientation.

Despite many efforts devoted toward the design of covalent organic frameworks (COFs) at the framework level by selecting the building blocks, their organization in the nano to meso regimes is often neglected. Moreover, the importance of processability for their applications has recently emerged and the synthesis of COF nanostructures without agglomeration is still a challenge. Herein, the first example of hybrid COF-polymer particles for which polymers are used to manipulate the 2D COF growth along a specific direction is reported. The study examines how the nature, chain-end functionality, and molar mass of the polymer influence the shaping of hybrid 2D boronate ester-linked COF-polymer particles. Catechol-poly(N-butyl acrylate) leads to the self-assembly of crystallites into quasi-spherical structures while catechol-poly(N-isopropylacrylamide) mediates the synthesis of raspberry-like COF-polymer particles with radial grain orientation. Scanning and transmission electron microscopies (SEM and TEM) and 4D-STEM-ACOM (automated crystal orientation mapping) highlight the single-crystal character of these domains with one plane family throughout the particles. Interestingly, the presence of PNIPAm on the particle surface allows their drying without co-crystallization and enables their resuspension. Kinetic investigations show that catechol-PnBuA acts as a modulator and catechol-PNIPAm induces a template effect, introducing supramolecular self-assembly properties into particles to create new morphologies with higher structural complexity, beyond the framework level.

Colorimetric sensing of dopamine in beef meat using copper sulfide encapsulated within bovine serum albumin functionalized with copper phosphate (CuS-BSA-Cu3(PO4)2) nanoparticles.

A novel nanosensor with peroxidase enzyme-mimetic activity, based on CuS-BSA-Cu3(PO4)2 nanoparticles, was developed. CuS-BSA nanoparticles were first synthesized using a facile bio-mineralization assay. Conjugation of Cu3(PO4)2 with CuS-BSA generates CuS-BSA-Cu3(PO4)2 nanoparticles (NPs) of 10 nm in size with high catalytic activity against a peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB). The catalytic action was based on a remarkable color change from colorless TMB into blue oxidized product (oxTMB) with absorption maximum at 654 nm. The enzyme-mimetic activity of CuS-BSA-Cu3(PO4)2 nanoparticles was believed to occur through hydroxyl radical (HO) generation in presence of H2O2, which was inhibited upon addition of dopamine. Increasing concentrations of dopamine induced a gradual decrease of the nanoparticles' catalytic activity. The developed colorimetric sensor displayed a limit of detection of 0.13 µM for dopamine over 0.05-100 µM linear range and high specificity. The performance of the nanosensor for sensing dopamine in beef meat and blood samples was evaluated and proved to be promising for diagnostic applications without the requirement of complex and expensive instrumentation.

Ultrasmall CuS-BSA-Cu3(PO4)2 nanozyme for highly efficient colorimetric sensing of H2O2 and glucose in contact lens care solutions and human serum.

This work reports on the synthesis of organic-inorganic hybrid nanoscale materials, CuS-BSA-Cu3(PO4)2. The developed nanoparticles were characterized by various techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The CuS-BSA-Cu3(PO4)2 were successfully applied as artificial colorimetric probes in sensing H2O2, the final outcome of glucose oxidation, and proved to be efficient peroxidase mimics for the catalytic conversion of a chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB), into a blue colored oxidized product (oxTMB) which can be easily visualized by the naked eye and monitored by a great absorption peak at 654 nm in the UV-vis spectrophotometry. A highly efficient, rapid, sensitive, and selective determination of H2O2 and glucose have been achieved with very low detection limits of 22 nM, and 27.6 nM over 0-8 µM and 0-1000 µM linear ranges, respectively. Compared to CuS-BSA, CuS-BSA-Cu3(PO4)2 exhibited improved peroxidase-like catalytic activity. Based on these observations, the performance of this approach was successfully validated in contact lens care solutions and human serum samples.

Substitution degree and fatty chain length influence on structure and properties of fatty acid cellulose esters.

A series of fatty acid cellulose esters (FACEs) with both various degrees of substitution (from DS = 1.7 to 3) and side chain length were obtained by grafting aliphatic acid chlorides (from C10 to C16) onto cellulose backbone, in a homogeneous LiCl/DMAc medium. These materials were characterized by Fourier Transformed InfraRed (FTIR) and Nuclear Magnetic Resonance of Proton (1H NMR) spectroscopies, as well as Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC), mechanical analyses and chemical resistance to concentrated acid and alkali solutions. Whatever the alkyl chains length and the DS, all samples displayed a layered structure composed of a planar arrangement of parallel cellulosic backbones with fully extended flexible side chains oriented perpendicular to the planar structure without interdigitation. The alkyl chains were able to crystallize as soon as they are long enough. As the DS decreased, the plasticizing effect of the alkyl chains was less pronounced and their ability to crystallize was improved. Regarding the mechanical behavior and the chemical resistance, similar results were observed whatever the DS is.