In order to overcome the performance barriers of polylactic acid (PLA), a multifunctional layered chitosan derivative, DAMC-Al, is synthesised and used as an intumescent flame retardant. The acid sources used in this work are 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and amino trimethylene phosphonic acid, which act synergistically to facilitate the conversion of chitosan to carbon. The combustion tests demonstrate that the PLA/ 5DAMC-Al exhibits excellent flame-retardancy with a limiting oxygen index of 30.3 % and a UL-94 flammability rating of V-0. The heat release rate and total heat release are significantly reduced compared to pure PLA, and the residual carbon expands rapidly. In addition, the composite has improved toughness while maintaining the stiffness of the PLA substrate, with a 31.0 % increase in elongation at break. DAMC-Al can also effectively block the transmission of 95 % of ultraviolet lights, protecting the PLA macromolecular chain from high-energy ultraviolet damage. Actually, the ultraviolet protection factor of PLA/5DAMC-Al is determined to be as high as 51.43. Furthermore, the soil degradation tests show that PLA/5DAMC-Al has the same excellent natural degradation properties as PLA.

Currently, the primary composition of fibrous filter materials predominantly relies on synthetic polymers derived from petroleum. The utilization of these polymers, as well as their production process, has a negative impact on the environment. Consequently, the adoption of air filter media fabricated from natural fibers would yield significant environmental benefits. Nowadays not only particle and odour capture performance but also ensuring a high energy efficiency and flame retardant properties in air filters is of utmost importance for automotive and HVAC filters. In this study, for the production of biodegradable and flame retardant air filters with a high quality factor, free standing gelatin/sodium alginate blend fibers were successfully produced via centrifugal spinning. The water-soluble mats were stabilized by physical methods using both thermal and ionic crosslinking. The CGCA (Crosslinked-Gelatin/Calcium Alginate) mat exhibited exceptional filtration performance for PM0.3 particles, achieving a 94.2 % efficiency rating at a pressure drop of 135 Pa. Moreover, blending of biopolymers and subsequent calcination provided V0 level flame retardancy according to UL94 standard. The preliminary biodegradation studies showed that proposed nanofibrous filters were completely degraded in soil in 7 days.

As a major alternative to the brominated flame retardants, the production and use of organophosphorus flame retardants (OPFRs) are increasing. And tris (1,3-dichloro-2-propyl) phosphate (TDCPP), one of the most widely used OPFRs, is now commonly found in a variety of products, such as building materials, furniture, bedding, electronic equipment, and baby products. TDCPP does not readily degrade in the water and tends to accumulate continuously in the environment. It has been detected in indoor dust, air, water, soil, and human samples. Considered as an emerging environmental pollutant, increasing studies have demonstrated its adverse effects on environmental organisms and human beings, with the nerve system identified as a sensitive target organ. This paper systematically summarized the progress of TDCPP application and its current exposure in the environment, with a focus on its neurotoxicity. In particular, we highlighted that TDCPP can be neurotoxic (including neurodevelopmentally toxic) to humans and animals, primarily through oxidative stress, neuroinflammation, mitochondrial damage, and epigenetic regulation. Additionally, this paper provided an outlook for further studies on neurotoxicity of TDCPP, as well as offered scientific evidence and clues for rational application of TDCPP in daily life and the prevention and control of its environmental impact in the future.

The prevalence of organophosphate esters (OPEs) in the global environment is increasing, which aligns with the decline in the usage of polybrominated diphenyl ethers (PBDEs). PBDEs, a category of flame retardants, were banned and classified as persistent organic pollutants (POPs) through the Stockholm Convention due to their toxic and persistent properties. Despite a lack of comprehensive understanding of their ecological and health consequences, OPEs were adopted as replacements for PBDEs. This research aims to offer a comparative assessment of PBDEs and OPEs in various domains, specifically focusing on their persistence, bioaccumulation, and toxicity (PBT) properties. This study explored physicochemical properties (such as molecular weight, octanol-water partition coefficient, octanol-air partition coefficient, Henry's law constant, and vapor pressures), environmental behaviors, global concentrations in environmental matrices (air, water, and soil), toxicities, bioaccumulation, and trophic transfer mechanisms of both groups of compounds. Based on the comparison and analysis of environmental and toxicological data, we evaluate whether OPEs represent another instance of regrettable substitution and global contamination as much as PBDEs. Our findings indicate that the physical and chemical characteristics, environmental behaviors, and global concentrations of PBDEs and OPEs, are similar and overlap in many instances. Notably, OPE concentrations have even surged by orders of several magnitude compared to PBDEs in certain pristine regions like the Arctic and Antarctic, implying long-range transport. In many instances, air and water concentrations of OPEs have been increased than PBDEs. While the bioaccumulation factors (BAFs) of PBDEs (ranging from 4.8 to 7.5) are slightly elevated compared to OPEs (-0.5 to 5.36) in aquatic environments, both groups of compounds exhibit BAF values beyond the threshold of 5000 L/kg (log10 BAF > 3.7). Similarly, the trophic magnification factors (TMFs) for PBDEs (ranging from 0.39 to 4.44) slightly surpass those for OPEs (ranging from 1.06 to 3.5) in all cases. Metabolic biotransformation rates (LogK(M)) and hydrophobicity are potentially major factors deciding their trophic magnification potential. However, many compounds of PBDEs and OPEs show TMF values higher than 1, indicating biomagnification potential. Collectively, all data suggest that PBDEs and OPEs have the potential to bioaccumulate and transfer through the food chain. OPEs and PBDEs present a myriad of toxicity endpoints, with notable overlaps encompassing reproductive issues, oxidative stress, developmental defects, liver dysfunction, DNA damage, neurological toxicity, reproductive anomalies, carcinogenic effects, and behavior changes. Based on our investigation and comparative analysis, we conclude that substituting PBDEs with OPEs is regrettable based on PBT properties, underscoring the urgency for policy reforms and effective management strategies. Addressing this predicament before an exacerbation of global contamination is imperative.

Polylactic acid (PLA) is recognized as a promising alternative to traditional petroleum-based plastics due to its excellent biodegradability and well-balanced mechanical properties. Nevertheless, the disadvantages of PLA such as flammability in fire, susceptibility to UV light attack, and slow natural degradation rate limit its application and recovery in high-security areas. In this work, a spherical chitosan-based additive DMPC-Al with mirrorsymmetric internal structure was assembled by layer-by-layer electrostatic reactions, resulting in PLA characterized excellent comprehensive performances. When 7 wt% DMPC-Al was added into PLA, the LOI value of the composite PLA/7DMPC-Al was increased to 29.6%, and UL-94 reached V-0 grade without any molten droplets. The peak heat release rate and total heat release rate were reduced by 13.5% and 16.2%, respectively, and the carbon layer was highly self-expanding. In addition, the UPF of PLA/7DMPC-Al was increased to 34.45 from 0.45 of pure PLA, blocking most of the UV light attacks and extending the service life of PLA. Surprisingly, DMPC-Al actually improved the impact toughness of PLA by 38.5% and facilitated PLA to work continuously when drawing large curved shapes by 3D printing. More importantly, the introduction of DMPC-Al changed the sensitivity of PLA to water and provided sufficient energy for microbial growth, thus accelerating the degradation rate of PLA in the soil under abandoned buildings. This work provides a practical and feasible strategy to achieve multifunctionality of degradable plastics.