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Biodegradable polymers and their blends have been advised as an eco-sustainable solution; however, the generation of microplastics (MPs) from their degradation in aquatic environments is still not fully grasped. In this study, we investigated the formation of bio-microplastics (BMPs) and the changes in the physicochemical properties of blown packaging films based on polylactic acid (PLA), polybutylene succinate (PBS) and a PBS/PLA 70/30 wt% blend after degradation in different aquatic media. The tests were carried out in two temperature/light conditions to simulate degradation in either warm water, under sunlight exposure (named Warm and Light-W&L), and cold deep water (named Cold and Dark-C&D). The pH changes in the aqueous environments were evaluated, while the formed BMPs were analyzed for their size and shape alongside with variations in polymer crystallinity, surface and mechanical properties. In W&L conditions, for all the films, the hydrolytic degradation led to the reorganization of the polymer crystalline phases, strong embrittlement and an increase in hydrophilicity. The PBS/PLA 70/30 blend exhibited increased resistance to degradation with respect to the neat PLA and PBS films. In C&D conditions, no microparticles were observed up to 12 weeks of degradation.

Inorganic⁻organic multilayer films consisting of polymers coated with thin inorganic oxidic layers (e.g., SiOx) ensure very high barrier performances against gas and vapor permeation, what makes them packaging materials suitable for sophisticated technical applications, including the encapsulation of photovoltaic devices or quantum dots, barrier films for optical displays, and transparent greenhouse screens. In these fields, surface coating or texturing of the multilayer protective films are effective technologies to improve their self-clean ability, thus reducing the required maintenance and ensuring longer durability and better performances. In this work, we used the self-assembled monolayer (SAM) technique to modify the surface and wetting properties of commercial polyethylene terephthalate-silicon oxide substrate (PET-SiOx) films developed for technical applications requiring a combined high barrier and transparency. The selected surface modifier was the 1H,1H,2H,2H-per-fluorodecyltrichlorosilane (FDTS). The reagent mixture composition was optimized for the lowest water and oil wettability, as well as the highest self-cleaning capacity and performance stability. In particular, for the used PET-SiOx film the best FDTS/film surface for both the lowest water and oil wettability was found to be equal to 26.5 mM/dm², which changes the surface behavior from very hydrophilic (static water contact angle (CAw) = 21.5°) to hydrophobic (CAw = 101°), and gives a significant increment of the static oil contact angle (CAo) from 27° to 60°. Interestingly, the results demonstrated that the SAM reaction occurred also on the uncoated the PET side. After the SAM treatment, a small increase of the water vapor permeability is observed, probably due to a crack or defect onset of the SiOx coating of the SAM modified films. On this point, atomic force measurements demonstrated an increment of the SiOx coating layer roughness after the SAM treatment execution. Finally, the transparency changes of the SAM treated films, measured in the wavelength range 400⁻800 nm, were always small, so that the results were acceptable for the films' use in applications where high transparency is required.