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The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR. Full article

Untreatable infections, growing healthcare costs, and increasing human mortality due to the rising resistance of bacteria to most of the available antibiotics are global phenomena that urgently require the discovery of new and effective antimicrobial agents. Cationic macromolecules, acting as membrane disruptors, are widely studied, and several compounds, including two styrene-based copolymers developed by us (P5 and P7), have proved to possess potent broad-spectrum antibacterial effects, regardless of the resistance profiles of the bacteria. Here, we first reported the synthesis and physicochemical characterization of new cationic nanoparticles (NPs) (CP1 and OP2), obtained by polymerizing the monomers 4-ammoniummethylstyrene (4-AMSTY) and 4-ammoniumethylstyrene (4-AESTY) hydrochlorides, whose structures were designed using the cationic monomers of P5 and P7 as template compounds. The antibacterial activity of CP1 and OP2 was assessed against several Gram-positive and Gram-negative multi-drug resistant (MDR) pathogens, observing potent antibacterial effects for both CP1 (MICs = 0.1–0.8 µM) and OP2 (MICs = 0.35–2.8 µM) against most of the tested isolates. Additionally, time-killing studies carried out with CP1 and OP2 on different strains of the most clinically relevant MDR species demonstrated that they kill pathogens rapidly. Due to their interesting physicochemical characteristics, which could enable their mutual formulation as hydrogels, CP1 and OP2 could represent promising ingredients for the development of novel antibacterial dosage forms for topical applications, capable of overcoming severe infections sustained by bacteria resistant to the presently available antibiotics. Full article