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.

Thermal Degradation Studies of Poly(2-ethyl hexyl acrylate) in the Presence of Nematic Liquid Crystals.

The thermal degradation behavior of Poly(2-ethyl hexyl hcrylate) (Poly(2-EHA)), blended with a commercially available nematic liquid crystal (LC) mixture, was investigated by thermal gravimetric analysis (TGA). Different heating rates, ranging from 5 to 200 °C/min, were applied under an inert atmosphere. Based on the TGA results, activation energies (Eα) at different conversion rates (α) were determined using three integral isoconversion methods: Flynn-Wall-Ozawa (FWO), Tang, and Kissinger-Akahira-Sunose (KAS). It can be noticed that the global evolution of these activation energies was the same for the three models. The coefficient of determination R2 presented values generally higher than 0.97. Using these models, the Eα value for the LC remains constant at 64 kJ/mol for all conversions rates. For the polymer Poly(2-EHA), applying the Tang and FWO models, the activation energy presents a variation ranging from 80 kJ/mol, for conversion α = 0.1, to 170 kJ/mol, for α = 0.9. For the third model (KAS), this energy varies between 80 and 220 kJ/mol in the same range of α.

Injectable Chitosan-Based Hydrogels for Trans-Cinnamaldehyde Delivery in the Treatment of Diabetic Foot Ulcer Infections.

Diabetic foot ulcers (DFU) are among the most common complications in diabetic patients and affect 6.8% of people worldwide. Challenges in the management of this disease are decreased blood diffusion, sclerotic tissues, infection, and antibiotic resistance. Hydrogels are now being used as a new treatment option since they can be used for drug delivery and to improve wound healing. This project aims to combine the properties of hydrogels based on chitosan (CHT) and the polymer of ß cyclodextrin (PCD) for local delivery of cinnamaldehyde (CN) in diabetic foot ulcers. This work consisted of the development and characterisation of the hydrogel, the evaluation of the CN release kinetics and cell viability (on a MC3T3 pre-osteoblast cell line), and the evaluation of the antimicrobial and antibiofilm activity (S. aureus and P. aeruginosa). The results demonstrated the successful development of a cytocompatible (ISO 10993-5) injectable hydrogel with antibacterial (99.99% bacterial reduction) and antibiofilm activity. Furthermore, a partial active molecule release and an increase in hydrogel elasticity were observed in the presence of CN. This leads us to hypothesise that a reaction between CHT and CN (a Schiff base) can occur and that CN could act as a physical crosslinker, thus improving the viscoelastic properties of the hydrogel and limiting CN release.

Release-killing properties of a textile modified by a layer-by-layer coating based on two oppositely charged cyclodextrin polyelectrolytes.

Infections represent a major medical concern and have severe impact on the public health economy. Antimicrobial coatings represent one major solution and are the subject of many investigations in academic and industrial research. Polyelectrolyte multilayers (PEMs) consist in the step-by-step deposition of polyanions and polycations films on surfaces. The wide range of disposable polyelectrolytes makes this approach among the most versatile methods as it allows to design surfaces that prevent bacterial adhesion, and kill bacteria by contact or by releasing antibacterial agents. The present work focused on the release-killing effect of an active PEM coating of a polyethylene terephthalate (PET) textile support. This activity was obtained thanks to the PEM film build up using cationic and anionic polyelectrolytes both based on cyclodextrins (PCD- and PCD+) that provided a reservoir property and prolonged release of triclosan (TCS). To this effect, a PET non-woven preliminarily modified with carboxylate groups by applying a thermofixation process was then treated by dip-coating, alternating soaking cycles in cationic PCD+ and in anionic PCD- solutions. Samples coated with such PEM film were then loaded with TCS whose release was assessed in dynamic mode in a phosphate buffered saline solution (PBS) at 37 °C. In parallel, TCS/PCD+ and TCS/PCD- interactions were investigated by Nuclear Magnetic Resonance (NMR) and phase solubility study, and the biocide activity was assessed against S. aureus and E. coli. Finally, the present study has demonstrated that our PCD+/PCD- PEM system presented release-killing properties that supplement the contact-killing effect of this system that was reported in a previous paper.

Synthesis and characterization of polyampholytic aryl-sulfonated chitosans and their in vitro anticoagulant activity.

This work firstly aimed to synthesize mono- and di- sulfonic derivatives of chitosan by reductive amination reaction using respectively 2-formyl benzene sulfonic acid and 2,4 formyl benzene sulfonic acid sodium salts. The influence of the reactants molar ratio (R), aryl - substituted amino groups versus chitosan free amino groups, on the degree of substitution (DS) of both sulfonated chitosans was assessed by 1H NMR, elemental analysis, coupled conductometry-potentiometry analysis and UV spectrometry and FTIR. The influence of pH on sulfonated chitosans' properties in solution were investigated by solubility and zeta potential (ZP) studies, size exclusion chromatography equipped with MALLS detection (SEC-MALLS) and Taylor dispersion analysis (TDA). The polyampholytic character of both series was evidenced and strongly modified the solutions properties compared to chitosan. Then, the anticoagulant properties of mono- and di- sulfonic polymers were investigated by the measurement of the activated partial thromboplastin time (aPTT), Prothrombin-time (PT) and anti-(factor Xa).

Layer-by-layer coating of textile with two oppositely charged cyclodextrin polyelectrolytes for extended drug delivery.

The coating of a nonwoven textile by polyelectrolyte multilayer film (PEM) issued from cationic and anionic ß-cyclodextrin (ßCD) polyelectrolytes according to the layer-by-layer (LbL) technique was successfully attempted. The tert-butyl benzoic acid (TBBA) was used as drug model to evaluate the loading capacity and sustained release properties of this PEM system. The build-up of the multilayer assembly was monitored in situ by optical waveguide lightmode spectroscopy (OWLS) on the one hand, and was assessed by gravimetry on the other hand when applied onto the textile substrate. In parallel, the complexation study of TBBA with both CD polyelectrolytes was also investigated by nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC). The influence of thermal crosslinking of the multilayered coating on its stability and on TBBA release kinetics in phosphate buffered saline (PBS) at 37°C was studied. Finally, biological and microbiological tests were performed to investigate the cytocompatibility and the intrisic antibacterial activity of multilayer assemblies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1408-1424, 2016.