Embedding depolymerizing enzymes in biodegradable plastics provides a promising strategy for developing self-biodegradable materials that degrade independently of external biological stimuli. However, the scalable melt processing of such materials remains fundamentally constrained by the intrinsic thermal fragility of enzymes. Here, we report a dual thermal protection mechanism that integrates molecular confinement and thermal insulation within a hydrophilic metal azolate framework (MAF-7) to extend enzyme stability to the melt-processing regime of hydrophobic polyesters. Proteinase K (pro K) was encapsulated within MAF-7 via a one-pot synthesis, where the mesoporous framework confined the enzyme and created a thermally insulated microenvironment. This protection preserved the secondary and tertiary structures of the enzyme, enabling pro K@MAF-7 to retain 70% of its catalytic activity after heating at 170 °C for 10 min. The unfilled pores of MAF-7 within the hydrophobic polylactide (PLA) melt ensured effective protection, and the resulting pro K@MAF-7/PLA composites processed by extrusion and hot pressing at 170 °C exhibited markedly accelerated hydrolysis, showing 70% weight loss after 84 days and nearly complete degradation in an aqueous buffer. The same protective mechanism was also applicable to lipase PS. This work establishes a versatile strategy for creating melt-processable, self-biodegradable plastics through metal-organic framework (MOF)-assisted enzyme confinement and molecular-scale thermal management.

Water-soluble polymers are materials rapidly growing in volume and in number of materials and applications. Examples include synthetic plastics such as polyacrylamide, polyacrylic acid, polyethylene glycol, polyethylene oxide and polyvinyl alcohol, with applications ranging from cosmetics and paints to water purification, pharmaceutics and food packaging. Despite their abundance, their environmental concerns (e.g., bioaccumulation, toxicity, and persistence) are still not sufficiently assessed, especially since water soluble plastics are often not biodegradable, due to their chemical structure. This review aims to overview the most important water-soluble and biodegradable polymers, their applications, and their environmental impact. Degradation products from water-insoluble polymers designed for biodegradation can also be water soluble. Most water-soluble plastics are not immediately harmful for humans and the environment, but the degradation products are sometimes more hazardous, e.g. for polyacrylamide. An increased use of water-soluble plastics could also introduce unanticipated environmental hazards. Therefore, excessive use of water-soluble plastics in applications where they can enter the environment should be discouraged. Often the plastics can be omitted or replaced by natural polymers with lower risks. It is recommended to include non-biodegradable water-soluble plastics in regulations for microplastics, to make risk assessments for different water-soluble plastics and to develop labels for flushable materials.

Embedding enzyme in biodegradable polyester accelerates hydrolysis in environments it ends up, but the release of microplastics (MPs) and nanoplastics (NPs) during this process remains underexplored. This work investigated the evolution of MPs and NPs released from poly(ε-caprolactone) (PCL) with embedded Lipase PS. The embedded enzyme significantly accelerated hydrolysis, causing the PCL film to disappear within 96 h. Notably, the formation rates and quantities of MPs and NPs were much higher compared to film with external enzyme. At 96 h, MPs (3.55 ×105 particles/mL) was 2.4 times, and NPs (4.65 ×107 particles/mL) was an order of magnitude higher than that with external enzyme. After 130 days, although both quantities and average size of MPs and NPs decreased due to only 90.6 % of enzymes were detected leaking, they did not completely disappear. The quantities of MPs and NPs were comparable to that with external enzyme, and the average size of MPs remained 1 μm. The simultaneous erosion inside film macroscopically, and severe chain cleavage microscopically, contributed to feasible film disintegration and formation of high amounts MPs and NPs. These findings underscore the importance of managing the release of MPs and NPs during the hydrolysis of enzyme-embedded biodegradable polyesters to ensure safety and mitigate environmental impact.

Biomass-derived materials are increasingly being incorporated into plastics to create biocomposites that reduce reliance on fossil-based feedstocks and lower carbon footprints. Maximizing the sustainability potential of these bio-based materials requires increasing their content within polymer matrices. However, a significant challenge arises: as bio-based content increases, performance trade-offs often arise. This study addresses this issue by examining the combined use of multiple bio-based components, specifically lignin and biochar, in acrylonitrilebutadiene-styrene (ABS) biocomposites. The bio-based content reached up to 44 wt%, while retaining adequate processability for extrusion and vacuum forming, as demonstrated by producing a miniature roof box sample. With this biocomposite composition, greenhouse gas emissions could be reduced by up to 40 %. Moreover, the fire performance was slightly improved by adding either lignin or biochar alone, while the combination of both fillers improved the fire performance significantly (a peak heat-release rate being half of that of ABS) due to a synergistic barrier-forming effect, limiting the transport of oxygen and fuel to the heat source and reducing heat transfer. The inclusion of both biochar and lignin influenced the mechanical properties of the composite, leading to an increase (33 %) in stiffness but a slight reduction (22 %) in strength. This study suggests that combining biochar and lignin can maximize bio-based content while improving critical performance characteristics, offering a viable pathway for more sustainable plastics.

A strategy to increase the biobased content and use of side-streams in plastic materials is to mix in biobased fillers available as inexpensive by-products. In line with this, herein, results on a polyolefin polymer with added wood powder (with or without a thermal treatment) and oat husk are presented, to make vacuum-formed products. The composite material is compounded, with or without a coupling agent, and then compression molded into sheets that are subsequently vacuum-formed. Despite a large content of fillers, the surface finish is in general smooth and uniform. The presence of filler increased, in general, the stiffness, and the use of the coupling agent is beneficial for the mechanical properties. The ductility and toughness, decreased in the presence of fillers, but the strain at break remained always larger than 10%. The fillers are all more hygroscopic than the polyolefin, which led to an increase in water uptake in the composites when immersed in water. The largest uptake, but still below 3.5% after 5 weeks, is observed for the material with oat husk. The results are overall promising, and open up for the use of biocomposites derived from industrial side-stream biofillers in vacuum-formed products.

Plastic pollution poses a critical global environmental challenge, and within this context, nanoplastics (NPs), the smallest plastic fragments, remain poorly understood. The progress in studying NP toxicity and developing analytical methods highly depends on access to well-defined NP materials. Herein, a straightforward and ecofriendly method for fabricating NP particles and fibrils using polymer blends as templates is presented. The process began with blending plastics with a water-soluble polymer (polyvinyl alcohol (PVA)), followed by the dissolution of the PVA matrix in water and the isolation of the NPs through a two-stage filtration process. NP materials from three widely used plastics, polyethylene, polypropylene, and polystyrene, were prepared, underscoring the versatility of this method. The resulting NPs were primarily submicron in size, and their size distribution was tuned by varying the blend ratio. Furthermore, by incorporating a stretch operation during the extrusion, the NP shape could be varied, enabling the fabrication of NP fibril materials. This method, which does not rely heavily on specialized equipment and avoids the use of harsh solvents, offers a viable and eco-friendly approach to fabricating NP samples suitable for a broad range of research applications.

Facile fabrication of green and renewable bio-based membranes with good anti-fouling and oil/water separation performance is of great importance to solve the oil spills and industrial oily wastewater threatening the ecological environment. Here, a fully biobased oil/water separation membrane with an ordered porous structure was 3D printed ultraviolet-assisted direct ink writing. The components of the bio-ink were obtained by methacrylation of chitosan (CS) and gelatin (GEL) to synthesize methacrylated chitosan (CSMA) and methacrylated gelatin (GELMA), while the nanographene oxide (nGO) was derived from CS through a simple microwave-assisted hydrothermal carbonization followed by oxidation step. The addition of nGO boosted the printability of the bio-ink, and the anti-fouling property and water permeation flux of the printed membranes. As a result, the membrane M−CSMA/GELMA/nGO-0.7 with the optimal performance possessed a low water contact angle in air of 0°, and high underwater oil contact angle of 161.5°, demonstrating a combination of superhydrophilic and underwater superoleophobic properties. M−CSMA/GELMA/nGO-0.7 has good corrosion resistance and long service life as evidenced from the separation efficiency of n-heptane/water, which kept above 99.5 % and a high water permeation flux above 38,300 L m−2h−1 after 20 cyclic tests in the harsh aquatic conditions containing 1 M NaCl, 1 M HCl, or 1 M NaOH, respectively. This shows promising potential for real-life applications.

Climate change and plastic pollution are interconnected global challenges. Rising temperatures and moisture alter plastic characteristics, contributing to waste, microplastic generation, and release of hazardous substances. Urgent attention is essential to comprehend and address these climate-driven effects and their consequences.

Accelerated thermal ageing (ATA) coupled to mechanical testing is widely used to predict the lifetime of poly-meric products. ATA implies that the mechanisms of ageing are the same at accelerated and service conditions, which may often not be the case. Hence, ageing closer to service conditions is of high importance, but require very sensitive tools. Therefore, a high sensitivity microcalorimetry (MC) method was applied here to assess if it can be a possible tool for lifetime/ageing prediction closer to service conditions. We chose to focus on a complex, yet commonly used, ethylene-propylene-diene terpolymer (EPDM) rubber. Arrhenius extrapolation of the heat flow data indicated two regimes at low and high temperature, with the former having the lower activation energy. The heat flow values measured by the MC revealed contributions from processes such as the melting of the antioxidant, its consumption at low temperature and the breakdown of residual peroxide. MC tests on the EPDM indicated a very low degree of oxidation appearing above 100 degrees C, too low to be observed with infra-red spectroscopy (FTIR), but noticeable with MC. The high sensitivity of the MC techniques enabled detection of early signs of polymer degradation/ageing and other thermally activated processes that take place at or close to service temperatures (such as those in nuclear power plants). The MC tests were combined with other techniques, such as scanning electron microscopy/energy dispersive X-ray spectroscopy, gas chromatography techniques, differential scanning calorimetry and FTIR to further understand the degradation mechanisms.

Biocomposites based on wheat gluten and reinforced with carbon fibers were produced in line with the strive to replace fossil-based plastics with microplastic-free alternatives with competing mechanical properties. The materials were first extruded/compounded and then successfully injection molded, making the setup adequate for the current industrial processing of composite plastics. Furthermore, the materials were manufactured at very low extrusion and injection temperatures (70 and 140 degrees C, respectively), saving energy compared to the compounding of commodity plastics. The sole addition of 10 vol % fibers increased yield strength and stiffness by a factor of 2-4 with good adhesion to the protein. The biocomposites were also shown to be biodegradable, lixiviating into innocuous molecules for nature, which is the next step in the development of sustainable bioplastics. The results show that an industrial protein coproduct reinforced with strong fibers can be processed using common plastic processing techniques. The enhanced mechanical performance of the reinforced protein-based matrix herein also contributes to research addressing the production of safe materials with properties matching those of traditional fossil-based plastics.