No abstract

Among different depollution methods, photocatalysis activated by solar light is promising for terrestrial outdoor applications. However, its use in underground structures and/or microgravity environments (e.g., extraterrestrial structures) is forbidden. In these cases, there are issues related to the energy emitted from the indoor lighting system because it is not high enough to promote the photocatalytic mechanism. Moreover, microgravity does not allow the recovery of the photocatalytic slurry from the depolluted solution. In this work, the synthesis of a filmable nanocomposite based on semiconductor nanoparticles supported by photosensitized copolyacrylates was performed through a bulk in situ radical copolymerization involving a photosensitizer macromonomer. The macromonomer and the nanocomposites were characterized through UV-Vis, fluorescence and NMR spectroscopies, gel permeation chromatography and thermogravimetric analysis. The photocatalytic activity of the sensitized nanocomposites was studied through photodegradation tests of common dyes and recalcitrant xenobiotic pollutants, employing UV-Vis and visible range (λ > 390 nm) light radiations. The sensitized nanocomposite photocatalytic performances increased about two times that of the unsensitized nanocomposite and that of visible range light radiation alone (>390 nm). The experimental data have shown that these new systems, applied as thin films, have the potential for use in indoor deep underground and extraterrestrial structures.

Environmental remediation of xenobiotic pollutants is an important issue in industrialized society. Catalyst‐mediated pollutant photodegradation using solar light shows promising results. Titanium dioxide nanoparticles (TiO2 NPs) are a well‐known standard for mineralizing organic water pollutants. Its use as a sludge pointed out the need to support this photocatalyst to ease both its use and recovery. Polymers represent a viable solution because of their versatility, stability, and cheapness. The in situ radical bulk polymerization approach to the development of TiO2‐based thermoplastic nanocomposites for xenobiotic photodegradation enhances the photocatalytic performance of the semiconductor nanoparticles. The versatility and efficiency of these systems pave the way for their industrial applications as photocatalytic coatings for large‐scale surfaces. To shed light on the influences of the chemical nature of the polymer matrix on the photocatalytic efficiency of the nanosystems, polyvinyl acetate, polymethyl methacrylate, and polystyrene are investigated as supports for TiO2 NPs. The obtained TiO2‐containing nanocomposites are characterized by thermal analyses, UV‐vis, Raman, and X‐ray photoelectron spectroscopies, dynamic light scattering, and contact angle measurements. The photocatalytic activity of the nanosystems in the form of thin films is investigated against pollutants in water solutions, and shows clear differences in the photodegradation efficiency among the nanocomposites having different chemical natures of polymers.

Space exploration missions are currently becoming more frequent, due to the ambition for space colonization in sight of strengthening terrestrial technologies and extracting new raw materials and/or resources. In this field, the study of the materials’ behaviour when exposed to space conditions is fundamental for enabling the use of currently existing materials or the development of new materials suitable for application in extra-terrestrial environments. In particular, the versatility of polymers renders them suitable for advanced applications, but the effects of space radiation on these materials are not yet fully understood. Here, to shed light on the effects of simulated solar wind on a polymeric material, polymethyl methacrylate (PMMA) was produced through radical bulk polymerization. The PMMA in the form of a thin film was subjected to proton beam bombardment at different fluences and in a high vacuum environment, with structural changes monitored through real-time FT-IR analysis. The structure of the residual material was investigated through MALDI-TOF mass spectrometry and 1H-NMR spectroscopy. The collected data allowed us to hypothesize the structural modifications of the PMMA and the related mechanisms.