Two-steps method to determine hydroxyl value and molecular weight of hydroxyl terminated polymers by¹⁹F-NMR measurements.

The current level of packaging consumption imposes a need to fabricate single-use food packaging with renewable and compostable materials, such as bio-polyesters (e.g., polylactic acid, PLA and polybutylene succinate, PBS) or cellulose, but their use is still problematic. Fabrication of bio-compostable composites can specifically address impeding challenges, and adhesive lamination, achieved with compostable glue, is becoming more and more popular with respect to the less versatile hot lamination. In this context, plasma activation, a chemical-free oxidation technique of a material’s surface, is used to increase the affinity of three different biomaterials (cellulose, PLA and PBS) toward a compostable polyurethane adhesive to decrease its amount by gluing bio-polyesters to cellulose. Optical Microscopy reveals activation conditions that do not affect the integrity of the materials, while Water Contact Analyses confirm the activation of the surfaces, with contact angles decreased to roughly 50 deg in all cases. Unexpectedly, ζ-potential analyses and subtractive infrared spectroscopy highlight how the activation performed superficially etches cellulose, while for both PLA and PBS, a general decrease in surface potential and an increase in superficial hydroxyl group populations confirm the achievement of the desired oxidation. Thus, we rationalize continuous activation conditions to treat PLA and PBS and to glue them to neat cellulose. While no beneficial effect is observed with activated PLA, bi-laminate composites fabricated with activated PBS fulfill the benchmark for adhesion strength using less than before, while oxygen permeation analyses exclude plasma-induced etching even at a nanoscale.

Mono-material multilayer polypropylene films were developed as light barrier structures through the incorporation of mineral-filled composite layers. Trilayer films with different layer arrangements were fabricated by thermocompression from polypropylene-based films containing 0, 1 and 5 wt.% of talc and kaolinite. A monolayer polypropylene film of equivalent total thickness was used as a control. Structural, thermal, mechanical, optical, and gas barrier properties were evaluated for all films fabricated. A well-defined trilayer structure was confirmed by SEM. FTIR analysis demonstrated negligible thermo-oxidation, with no thermal-degradation during processing. Improved thermal stability and a slight modification in crystallinity were evidenced by TGA and DSC, respectively. XRD revealed the predominance of the α-form crystalline phase and a preferential polymer crystal orientation associated with the particle presence. Regarding mechanical behavior, enhanced stiffness and tensile strength without loss of sealability or puncture resistance were observed. Trilayer films exhibited significantly reduced UV and visible light transmittance, while maintaining adequate translucency, making them suitable for photosensitive packaging applications. Gas permeabilities remained nearly unchanged, confirming that the barrier performances were preserved. Overall, these mono-material multilayer composites films offer a promising and recyclable alternative to conventional multi-material light barrier packaging, combining improved UV protection, mechanical robustness, and environmental compatibility.

Hydrogen will be the energy vector of our future, but cost-effective production of such gas is still far from being established. Nowadays, major issues in hydrogen synthesis are its cost-effective separation from process byproducts, mainly CO₂ or CH₄. Bottom-up fabrication of molecular nanoarchitectures composed of sheets of 2D materials such as graphene oxide (GO) offers a potentially tunable platform to prepare versatile gas membranes able to obtain pure hydrogen for industrial applications. In this work, we assembled a series of PDDA–GO composite nanomaterials with tunable thickness, exploiting the strong interaction between GO and PDDA and varying the number of deposition cycles. Surprisingly, we observed excellent selectivity for hydrogen even after one single deposition cycle, with the membrane ca. 4 nm thick showing the highest permeance. Using extensive characterization with quartz crystal microbalance, atomic force microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy, we could attribute such an unexpected combination of selectivity/permeance to the formation of an interpenetrated multilayered structure with GO sheets spaced approximately 1.1 nm apart and intercalated by polymer chains, which self-assemble forming an intercalated layered structure even after a single deposition cycle. This approach could significantly reduce the complexity and cost of production for gas separation membranes.