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Understanding visible light and microbe-driven degradation mechanisms of polyurethane plastics: Pathways, property changes, and product analysis
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Researchers found that polyurethane plastics break down in water through a combination of microbial action and light exposure, producing secondary microplastics as they degrade. This study reveals a previously underappreciated source of microplastic pollution, since polyurethane is widely used in coatings, foams, and other products that often end up in waterways.
The accumulation of polyurethane plastics (PU-PS) in the environment is on the rise, posing potential risks to the health and function of ecosystems. However, little is known about the degradation behavior of PU-PS in the environment, especially water environment. To address this knowledge gap, we investigated and isolated a degrading strain of Streptomyces sp. B2 from the surface of polyurethane coatings. Subsequently, a photoreactor was employed to simulate the degradation process of bio-based polyurethane (BPU) and petroleum-based polyurethane (PPU) under three conditions, including single microorganism (SM), single light exposure (SL), and combined light exposure/microorganism action (ML) in aqueous solution. The results indicated that PU-PS mainly relies on biodegradation, with the highest degradation rate observed after 28 d under SM condition (BPU 5.69 %; PPU 5.25 %). SL inhibited microbial growth and degradation, with the least impact on plastic degradation. Microorganisms colonized the plastic surface, secreting relevant hydrolytic enzymes and organic acids into the culture medium, providing a negative charge. The carbon chains were broken and aged through hydrogen peroxide induction or attack by oxygen free radicals. This process promoted the formation of oxidized functional groups such as OH and CO, disrupting the polymer's structure. Consequently, localized fragmentation and erosion of the microstructure occurred, resulting in the generation of secondary microplastic (MPs) particles, weight loss of the original plastic, increased surface roughness, and enhanced hydrophilicity. Additionally, BPU exhibited greater degradability than PPU, as microorganisms could utilize the produced fatty acids, which promoted their reproduction. In contrast, PPU degradation generated a large amount of isocyanate, potentially toxic to cells and inhibiting biodegradation. This study unveils the significant role of microorganisms in plastic degradation and the underlying degradation mechanisms of BPU, providing a novel strategy for polyurethane degradation and valuable information for comprehensive assessment of the behavior and fate of MPs in the environment.
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Effects of UV light on physicochemical changes in thermoplastic polyurethanes: Mechanism and disinfection byproduct formation
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Researchers examined how UV light exposure changes the properties of thermoplastic polyurethane microplastics in water and whether those changes affect the formation of harmful disinfection byproducts during water chlorination. They found that UV exposure broke the plastic into smaller fragments and released soluble chemicals that significantly increased byproduct formation after chlorination. The findings suggest that aging microplastics in water systems could contribute to the creation of potentially harmful chemicals during standard water treatment.
Photochemical weathering of polyurethane microplastics produced complex and dynamic mixtures of dissolved organic chemicals
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Researchers studied how sunlight breaks down polyurethane microplastics in ocean surface waters and what chemical byproducts are released. The study found that photochemical weathering produced complex and constantly changing mixtures of dissolved organic chemicals, with different polyurethane types releasing different compounds. The findings reveal that while sunlight helps degrade microplastics, the resulting chemical cocktails may themselves pose environmental risks.
Photodegradation behavior of different polyurethane: A comparison study of foam and leather
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Polyurethane plastics, used in everything from furniture foam to synthetic leather, can break down under sunlight into microplastics and dissolved chemicals — including from carcinogenic starting materials. This study compared how foam-based and leather-based polyurethanes degrade under UV light, finding that foam degraded faster and released more nanoscale plastic particles and dissolved organic matter. Understanding these differences matters because it affects how toxic the resulting microplastics are, and which polyurethane products pose the greatest risks as they age in the environment.
From macroplastics to microplastics: Role of water in the fragmentation of polyethylene
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Laboratory photodegradation experiments compared how polyethylene plastic films fragment in water versus air under UV light, finding that the aquatic environment significantly influences the physical and chemical breakdown of plastic into microplastics. The study improves understanding of how water immersion changes the photodegradation pathways of floating and submerged plastic debris.
Insight into the chemical transformation and organic release of polyurethane microplastics during chlorination
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Scientists investigated what happens to polyurethane microplastics during water chlorination, a standard step in water treatment. They found that chlorination breaks down the plastic surface and releases organic chemicals, especially from UV-weathered particles, which produced significantly more leached compounds. The findings suggest that water treatment processes themselves may inadvertently release harmful byproducts from microplastics.
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