Search

Because of widespread public concern about plastic waste treatment and recycling, there is a global trend toward replacing non-biodegradable polymers with biodegradable polymers. However, the inherent flammability of most biodegradable polymers presents a significant barrier to their potential application, necessitating the rapid development of fire-retardant biodegradable polymers. Herein, three major categories of fire retardants (FRs), including intrinsic FRs, additive FRs, and fire-retardant coatings, especially widely studied additive FRs in the categories of organic, inorganic, and inorganic–organic, are reviewed, revealing how the physical and chemical structures of FRs affect the fire-retardant efficiency of biodegradable polymers and concluding the influencing factors of their fire retardance from the perspective of the physical and chemical structures of FRs. This work provides fundamental data and mechanistic analyses for the fire-retardant parameters of biodegradable polymers by integrating/adding diverse types of FRs, to provide guidance for fabricating highly efficient fire-retardant biodegradable polymer materials and inspiring the development of future research and application of functional biodegradable polymers toward circular economy and greater sustainability. [ABSTRACT FROM AUTHOR]

Frequent fire disasters have caused massive impacts to the environment, human beings, and the economy. MXene has recently been intensively researched as potential flame retardants to provide passive fire protection for other materials via its physical barrier and catalyzing carbonization effects. In parallel, MXene has also demonstrated a great promise for creating early fire warning sensors, which is an emerging field that has the potential to provide active fire response through its thermoelectric effect. This makes it possible to integrate passive fire retardancy and active fire warning into one MXene‐based fire protection system on demand. However, fulfilling these promises needs more research. Herein, an overview of passive flame‐retardant materials and next‐generation smart fire warning materials/sensors based on MXene and its derivatives is provided. This study reviews their conceptual design, characterization, modification principles, performances, applications, and mechanisms. A discussion of the challenges that need to be solved for their future practical applications and opportunities is also presented. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis and polymerization performances of terpenoid‐derived camphoric anhydride (CA). Utilizing simple organo‐base tBuP2 as the catalyst, CA can polymerize with various epoxides by efficient and controlled ring‐opening alternating copolymerization (ROAC) to afford perfectly alternating poly(CA‐alt‐epoxide). Kinetic study shows that the polymerization proceeds following zero‐order dependence on the concentration of CA. The self‐switchable terpolymerization from the mixture of CA, propylene oxide (PO) and ε‐caprolactone (CL) is conducted under the catalysis of tBuP2. First, ROAC of CA and PO is carried out exclusively with benzyl alcohol as initiator. Then, block copolymer (BCP) poly(CA‐alt‐PO)‐b‐PCL is obtained via the sequential polymerizations after the complete consumption of CA. The followed ring‐opening polymerization (ROP) of CL is initiated by the terminal hydroxyl of the ROAC‐resulted poly(CA‐alt‐PO) polyester without external stimulus. During the process, the excess PO compound remains intact. The one‐pot synthesis displays distinct living nature and perfect chemoselectivity. The as‐prepared terpenoid‐derived alternating and BCP's exhibit elevated thermal properties. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy (DN) is a fatal complication of diabetes and the main cause of end-stage renal disease. Due to the suboptimal effects of current treatments, there is an urgent need to develop new therapeutic strategies for DN. Trametenolic acid (TA), a lanostane-type tetracyclic triterpenoid, is one of the main active ingredients extracted from the natural product Inonotus obliquus. Our study was aimed at clarifying the potential protective effects of TA on DN and its underlying mechanism. In this research, C57BLKS/db (db/db) mice were used as the spontaneous DN model, and TA (10 mg/kg/d) was intraperitoneally injected for 4 consecutive weeks. Ratio of right kidney weight/body weight was calculated, and the contents of serum creatinine (Scr), blood urea nitrogen (BUN), and urine albumin were detected. The activities of superoxide dismutase (SOD) and catalase (CAT) and the contents of reductive glutathione (GSH) and malondialdehyde (MDA) were measured. The histopathological changes of renal tissues were observed by hematoxylin and eosin (HE), periodic acid-Schiff (PAS), and Masson staining. The protein expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase-1 (NQO-1), nuclear factor kappa B (NF-κB), proinflammation cytokine tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), Nephrin, and Podocin were detected by western blot assay. Immunohistochemistry was utilized to detect expressions of collagen III (COL-III) and fibronectin (FN). Our results showed that TA administration significantly reduced the ratio of right kidney weight/body weight, BUN, Scr, and urine albumin levels and alleviated the histopathological changes of DN mice. Moreover, TA administration remarkably increased GSH content and SOD and CAT activities and decreased MDA content. Western blot assay demonstrated that TA activated Nrf2 signaling and increased the expression of downstream antioxidant enzymes HO-1 and NQO-1. Further studies illustrated that NF-κB signaling was inhibited, and downstream proinflammation cytokine expressions of TNF-α, IL-6, and IL-1β were also downregulated. In addition, we also found that TA administration significantly increased the expression of nephrin and podocin proteins and reduced the protein expression of COL-III and FN. These findings suggested that TA exhibited a renoprotective effect by ameliorating oxidative stress and inflammation via Nrf2/HO-1 and NF-κB signaling pathways. [ABSTRACT FROM AUTHOR]

In this article, a solid-state mechanochemical method based on a pan-mill equipment was used to prepare 60 wt % loading of wood flour (WF) incorporated polypropylene (PP) wood-plastic composite (WPC) with good comprehensive performance. The particle size distribution, crystallization, microstructure, and properties of the prepared WPC were accordingly investigated. The results show that under co-effects of the strong shear force field of pan milling and the compatibilization of PP grafted maleic anhydride (PP-g-MAH), the mixture of PP and WF is effectively pulverized and homogeneously mixed. Meanwhile, the WF particles are adequately activated by exposure of their characteristic functional groups, which is beneficial to the interfacial mechanochemical reaction. PP-g-MAH and PP prove to be in situ grafted onto WF particles surface during pan milling, thus resulting in the substantial enhancement in both the dispersion of the added WF fillers in PP matrix and the interfacial bonding. The mechanochemical effects of pan milling could also remarkably promote the heterogeneous nucleation effect of WF particles on PP crystallization and influence the dynamic mechanical behavior of composite. Compared with the unmilled and uncompatibilized composite, the milled and compatibilized WPC material possesses greatly enhanced mechanical performance and shows good application prospects. [ABSTRACT FROM AUTHOR]

Highlights Polylactide (PLA) biocomposite filaments containing hemp hurd (HH) of variable particle size were evaluated in comparison with injection‐molded counterparts using single/twin screw extrusion in this study. HH particle size (35, 50, and 160 μm) was parametrically investigated for its efficacy within PLA/HH biocomposites and fused filament fabrication (FFF)‐printed parts by assessing its effect on performance through rheological, microstructural, mechanical, and surface finish analyses. In addition, melt flow indexing, rheometry, scanning electron microscopy, mechanical testing, and x‐ray computed tomography were utilized to analyze microstructure, mechanical performance, and surface roughness. With an increase in particle size of the HH, the corresponding biocomposites showed increased flowability, and the injection‐molded specimens showed increased impact strength. The FFF printing of the biocomposite filament presented no challenges, and the mechanical properties of FFF parts enhanced with a particle size smaller than the printed layer thickness. Compared with injection‐molded parts, FFF‐printed samples showed higher impact strength. The FFF‐printed PLA/HH biocomposite samples showed considerable potential over their injection molded alternatives for low‐volume specialized applications. Polylactide (PLA)/hemp hurd (HH) biocomposite filaments with different particle sizes of HH were developed. Melt flow and impact strength increased when HH particle size increased. 3D‐printed part porosity and roughness increased when HH particle size increased. Higher HH particle size enhanced the mechanical performance of 3D‐printed parts. 3D‐printed parts exhibited higher impact strength than injection molded parts [ABSTRACT FROM AUTHOR]

It is critically important to maintain the body's thermal comfort for human beings in extremely cold environments. Cellulose nanofibers (CNF)-based aerogels represent a promising sustainable material for body's heat retention because of their renewability and low thermal conductivity. However, CNF-based aerogels often suffer high production costs due to expensive CNF, poor elasticity and/or unsatisfactory thermal insulation owing to improper microstructure design. Here, a facile dual-template strategy is reported to prepare a low-cost, hyperelastic, superhydrophobic Fuller-dome-structured CNF aerogel (CNF@PU) with low thermal conductivity. The combination of air template by foaming process and ice template enables the formation of a dome-like microstructure of CNF@PU aerogel, in which CNF serves as rope bars while inexpensive polyurethane (PU) acts as joints. The aerogel combines ultra-elasticity, low thermal conductivity (24 mW m -1 K -1 ), and low costs. The as-prepared CNF@PU aerogel demonstrates much better heat retention than commercial thermal retention fillers (e.g., Flannelette and goose down), promising its great commercial potential for massively producing warming garments. This work provides a facile approach for creating high-performance aerogels with tailored microstructure for effective personal thermal management., (© 2024 Wiley‐VCH GmbH.)

Fire-retardant coatings represent a universal cost-effective approach to providing fire protection for various substrates without compromising substrates' bulk properties. However, it has been attractive yet highly challenging to create waterborne polymeric fire-retardant coatings combining high-efficiency, generally strong adhesion, and self-repairability due to a lack of rational design principles. Inspired by mussel's unique adhesive, self-healing, and char-forming mechanisms, herein, a "group synergy" design strategy is proposed to realize the combination of self-healing, strong adhesion, and high efficiency in a fully polymeric fire-retardant coating via multiple synergies between catechol, phosphonic, and hydroxyethyl groups. As-created fire-retardant coating exhibits a rapid room-temperature self-healing ability and strong adhesion to (non)polar substrates due to multiple dynamic non-covalent interactions enabled by these groups. Because these functional groups enable the formation of a robust structurally intact yet slightly expanded char layer upon exposure to flame, a 200 µm-thick such coating can make extremely flammable polystyrene foam very difficult to ignite and self-extinguishing, which far outperforms previous strategies. Moreover, this coating can provide universal exceptional fire protection for a variety of substrates from polymer foams, and timber, to fabric and steel. This work presents a promising material design principle to create next-generation sustainable high-performance fire-retardant coatings for general fire protection., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Diabetic nephropathy (DN) is a fatal complication of diabetes and the main cause of end-stage renal disease. Due to the suboptimal effects of current treatments, there is an urgent need to develop new therapeutic strategies for DN. Trametenolic acid (TA), a lanostane-type tetracyclic triterpenoid, is one of the main active ingredients extracted from the natural product Inonotus obliquus . Our study was aimed at clarifying the potential protective effects of TA on DN and its underlying mechanism. In this research, C57BLKS/db (db/db) mice were used as the spontaneous DN model, and TA (10 mg/kg/d) was intraperitoneally injected for 4 consecutive weeks. Ratio of right kidney weight/body weight was calculated, and the contents of serum creatinine (Scr), blood urea nitrogen (BUN), and urine albumin were detected. The activities of superoxide dismutase (SOD) and catalase (CAT) and the contents of reductive glutathione (GSH) and malondialdehyde (MDA) were measured. The histopathological changes of renal tissues were observed by hematoxylin and eosin (HE), periodic acid-Schiff (PAS), and Masson staining. The protein expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase-1 (NQO-1), nuclear factor kappa B (NF- κ B), proinflammation cytokine tumor necrosis factor- α (TNF- α ), interleukin-6 (IL-6), interleukin-1 β (IL-1 β ), Nephrin, and Podocin were detected by western blot assay. Immunohistochemistry was utilized to detect expressions of collagen III (COL-III) and fibronectin (FN). Our results showed that TA administration significantly reduced the ratio of right kidney weight/body weight, BUN, Scr, and urine albumin levels and alleviated the histopathological changes of DN mice. Moreover, TA administration remarkably increased GSH content and SOD and CAT activities and decreased MDA content. Western blot assay demonstrated that TA activated Nrf2 signaling and increased the expression of downstream antioxidant enzymes HO-1 and NQO-1. Further studies illustrated that NF- κ B signaling was inhibited, and downstream proinflammation cytokine expressions of TNF- α , IL-6, and IL-1 β were also downregulated. In addition, we also found that TA administration significantly increased the expression of nephrin and podocin proteins and reduced the protein expression of COL-III and FN. These findings suggested that TA exhibited a renoprotective effect by ameliorating oxidative stress and inflammation via Nrf2/HO-1 and NF- κ B signaling pathways., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Qi Duan et al.)