Nanoscale analysis of plastic contaminants migration in packaging materials and potential leaching into model food systems

Polymers are the most common packaging materials used for food, beverages, cosmetics, and other consumer products. The ever-growing concern over pollution generated from single-use packaging materials, and the ensuing potential environment contamination resulting from their use has raised safety questions. Polymers used in these materials are often not spared from the presence of impurities, including unreacted monomers and small oligomers. The characterization of transport properties, including diffusion and leaching of these penetrant molecules is largely hampered by the long timescales involved in shelf-life experiments. In this work, we employ molecular simulation techniques to explore the main mechanisms involved in the bulk and interfacial transport of monomer molecules from three polymers commonly employed as packaging materials: polyamide-6, polycarbonate, and poly(methyl-methacrylate). Our simulations shed light on the main diffusion mechanisms for in- and outbound penetrant diffusion and provide rationalization for monomer leaching in model food formulations as well as bulky industry-relevant molecules. With these molecular-scale characterization we provide base insights to aid the design of polymer/consumer product interfaces with reduced risk of contamination and longer shelf-life

Molecular simulation of natural gas storage in Cu-BTC metal–organic framework

We tested the MOF framework Cu-BTC for natural gas (NG) storage. Adsorption isotherms of C1–C4 alkanes were simulated applying the Grand Canonical ensemble and the Monte Carlo algorithm in a classical molecular mechanics approach. Experimental monocomponent isotherm of the alkanes was used to validate the force field. We performed multicomponent adsorptions calculations for three different quaternary mixtures of C1–C4 alkanes, matching typical NG streams composition, and predicted theoretical storage capacities, efficiency and accumulation of the NG within that composition. Despite being one of the frameworks with greatest storage capacity of methane, we found that Cu-BTC presented great sensitivity to the variation of the heavier alkanes in NG composition. When we increase the percentage of butane from 0.1% to 0.7% in the mixture, the mass of components retained in the discharge pressure (1 bar) increases from 35 to 60%. We also perform siting and interaction energy investigations and compare the NG storage performance of the Cu-BTC with that of activated carbons. To our knowledge, this is the first study regarding the efficiency of the NG storage in Cu-BTC