Self-Standing Bioinspired Polymer Films Doped with Ultrafine Silver Nanoparticles as Innovative Antimicrobial Material.

Thin self-standing films with potential antimicrobial synergistic activity have been produced by a simple green chemical synthesis with overnight thermal treatment. Their properties have been studied by scanning electron microscopy, X-ray photoelectron spectroscopy and other techniques to understand their potential range of applications. In this work, the focus was set on the development of a potential novel and effective alternative to conventional antimicrobial materials. By creating an antimicrobial polymer blend, and using it to develop and immobilize fine (~25 nm) silver nanophases, we further aimed to exploit its film-forming properties and create a solid composite material. The resulting polymer matrix showed improved water uptake percentage and better stability in the presence of water. Moreover, the antimicrobial activity of the films, which is due to both organic and inorganic components, has been evaluated by Kirby-Bauer assay against common foodborne pathogens (Staphylococcus aureus and Salmonella enterica) and resulted in a clear inhibition zone of 1.2 cm for the most complex nanocomposition. The excellent performance against bacteria of fresh and 6-month-old samples proves the prospects of this material for the development of smart and biodegradable food packaging applications.

Microemulsion Microstructure(s): A Tutorial Review.

Microemulsions are thermodynamically stable, transparent, isotropic single-phase mixtures of two immiscible liquids stabilized by surfactants (and possibly other compounds). The assortment of very different microstructures behind such a univocal macroscopic definition is presented together with the experimental approaches to their determination. This tutorial review includes a necessary overview of the microemulsion phase behavior including the effect of temperature and salinity and of the features of living polymerlike micelles and living networks. Once these key learning points have been acquired, the different theoretical models proposed to rationalize the microemulsion microstructures are reviewed. The focus is on the use of these models as a rationale for the formulation of microemulsions with suitable features. Finally, current achievements and challenges of the use of microemulsions are reviewed.

Chemical Recycling of Poly(bisphenol A carbonate) by Glycolysis under 1,8-Diazabicyclo[5.4.0]undec-7-ene Catalysis.

The glycolysis reaction of poly(bisphenol A carbonate) (PC) has been explored under 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalysis as a potential route to valorize PC wastes by chemical recycling. The amidine base is an active catalyst of PC glycolysis and, under suitable conditions, promotes effectively and selectively the depolymerization of the polymeric material with 1,2-propanediol or glycerol to give the monomer bisphenol A (BPA) and the relevant cyclic carbonate. The depolymerization process has been investigated under solventless conditions, using diol/triol as the reagent and reaction medium, and also in an auxiliary solvent such as tetrahydrofuran (THF) that is able to dissolve the polymer. The influence of a few experimental parameters (temperature, catalyst load, and reaction time) on the selectivity to cyclic carbonate has been studied. High selectivity to cyclic carbonate has been attained by carrying out the depolymerization reaction in THF and using mild temperature conditions and a stoichiometric amount of polyol. The catalyst can be recovered from the reaction mixture as a BPA/DBU adduct and effectively recycled in a successive run.