3D flower-like Gd3+-doped titanium dioxide (Gd3+-TiO2) catalysts were designed and synthesized via a facile hydrothermal method. The catalysts featured an interwoven lamellar network, anatase crystal phase, Gd-O-Ti bonds, abundant oxygen vacancies, and weak Lewis acidity. Among the series, Gd3+-TiO2-0.5% (0.5% mol/mol of TiO2) exhibited optimal performance, with acid amount of 260.92 mu mol/g, specific surface area of 79.13 m2/g, and average pore diameter of 23.81 nm. Notably, its catalytic performance outperformed that of several representative metal catalysts (e.g., tin(II) oxalate, GeO2) and the organic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The resultant PEF possessed a high number-average molecular weight (Mn) of 6.7 & times; 104 g/mol, low ether bond content of 2.8%, excellent optical transparency and color, a prolonged crystallization half-time (t1/2) of 22.72 min, and superior thermal stability. The elastic modulus (Et) and maximum tensile stress (sigma) of PEF film were 2256 +/- 38 MPa and 64 +/- 11 MPa, respectively. This work provides a feasible strategy for fabricating advanced catalysts via 3D structural engineering and rare-earth doping, which holds great promise for the synthesis of high-performance bio-based polyesters.

Polyamide 11 (PA11) is an attractive bio-based electroactive polymer for flexible piezoelectric devices because of its mechanical compliance, facile processability, and inherent polarity. However, its piezoelectric performance is still limited by the insufficient content of electroactive phases and the strong intermolecular hydrogen-bonding constraints that govern chain packing. Herein, we propose a mild and filler-free small-molecule modulation strategy that reconstructs the hydrogen-bond network of PA11 with hydroxyl-bearing modifiers to steer its crystallization pathway toward electroactive phases. Using 2,5-dimethyl-2,5-hexanediol (DMHD) as a typical hydroxyl-bearing modifier, we show that DMHD can competitively hydrogen-bond with PA11 amide groups, loosening native interchain constraints and promoting the transition from the weakly electroactive, antiparallel α phase to the electroactive δ′ phase. Benefiting from the synergistic optimization of crystal structure and intermolecular interactions, the PA11/DMHD composites exhibit markedly enhanced piezoelectric output performance. In particular, the optimized PA11/DMHD7-based device delivers an open-circuit voltage of 13.05 V and a short-circuit current of 404 nA, approximately three times higher than those of pristine PA11, shows a stable linear response in the 1–5 N range, and maintains reliable output over 1800 loading cycles. Meanwhile, the device demonstrates practical applicability in human-motion monitoring and pressure sensing. This work provides a mild, scalable and filler-free strategy for crystal-phase engineering and performance optimization of polyamide-based piezoelectric polymers, offering promising prospects for wearable electronics and self-powered devices.

The advancement of electrochemical sensing platforms designed for the precise detection of trace-level heavy metal ions (HMIs) is critically important in addressing the escalating environmental and public health challenges. This study presents a nitrogen-defect-enriched manganese nitride (Mn2N0.86) integrated onto nitrogen-doped carbon nanotube substrates (Mn2N0.86/N-CNTs), serving as a non-precious-metal-based system for voltametric quantification of Pb2+, Cd2+, Hg2+, and Cu2+ in aqueous environments. Morphological and structural characterizations conducted using SEM, TEM, XRD, XPS, and EPR revealed the presence of multiple valence states of manganese, nitrogen vacancies, as well as pyridinic-N, pyrrolic-N, and graphitic-N within the Mn2N0.86/N-CNTs material. The incorporation of nitrogen vacancies along with the redox mediation involving mixed-valence Mn2+/Mn3+ significantly enhanced both the adsorption capacity and catalytic performance of Mn2N0.86/N-CNTs, thereby improving its electroanalytical efficacy for HMIs. This platform achieved remarkable detection limits for Pb2+, Cd2+, Hg2+, and Cu2+ at concentrations as low as 5.3 nM, 4.5 nM, 15.9 nM, and 10.6 nM respectively. Furthermore, this electrode exhibits excellent stability, reproducibility, and anti-interference capabilities while enabling accurate detection in real water samples. This work establishes a paradigm for transition metal nitride-based sensors through vacancy engineering coupled with substrate optimization; offering an innovative strategy for environmental monitoring.

Polyamide 6 (PA 6) is an important polymer widely used in daily life. However, increasing demands for high performance and recyclability, driven by cutting-edge applications and the ongoing energy crisis, have presented major challenges to the development of PA 6. In this work, we report a simple copolymerization method to design a PA 6 copolymer with high performance and chemical recyclability. A functional monomer named ISA was synthesized via the imidization reaction between isatoic anhydride and the active amino group in alpha-amino epsilon-caprolactam, a mature bio-based platform molecule. The chemical similarity between ISA and caprolactam (CPL) ensured high-quality polymerization, resulting in the corresponding copolymer PA 6-co-ISA with high molecular weight, excellent spinnability, great melt-crystallization performance, and mechanical robustness. As expected, high flame retardancy was obtained thanks to the gaseous dominated flame-retardant effect of the Ncontaining heterocyclic ring. More importantly, owing to the unchanged polymeric main chain structure, the copolymer could be easily recycled to CPL, and the repolymerized polymer showed great overall properties equal to the original one. This work provides a feasible approach for the preparation of high-performance and closedloop recyclable polymeric materials.

Magnesium alloys are widely used in all kinds of fields because of their excellent mechanical properties, but their application has been prevented by poor corrosion resistance. In this paper, Mg(OH)2-Ca(OH)2/Al(OH)3/Al2O3 composite coatings with long-term corrosion resistance were fabricated on the surface of Mg alloys using the hydrothermal method. Among them, the calcium hydroxide/calcium nitrate–alumina coating successfully filled the cracks in the magnesium hydroxide coating. Meanwhile, we explored the influences of different heating times and temperatures on the coating and analyzed its composition. After immersing the coating in a 3.5% NaCl solution for 168 h, only a small portion of the surface dissolved. Electrochemical test results indicated that the corrosion potential and corrosion current density of the coating increased by three orders of magnitude, significantly improving corrosion resistance in comparison to bare samples. Adhesion tests showed that the coating exhibited good bonding performance to the substrate. This method features a simple, pollution-free preparation process and does not require complex instrumentation, thereby enhancing the longevity of the magnesium alloy.

With the increasing public awareness of safety and the ongoing global legislation on the use of flame retardants, the development of eco-friendly flame-retardant methods has become an urgent issue. In this study, we utilized the room-temperature hydrogen-bonding effect and the high-temperature rearrangement inherent in the functional hydroxyl-containing phenylimide structure to engineer a flame-retardant, high-performance aliphatic polyamide. Remarkably, the obtained polyamide copolymer was exclusively composed of the elemental constituents inherent to polyamide itself, i.e., carbon, hydrogen, oxygen, and nitrogen. As expected, the high-temperature rearrangement along with the corresponding char-forming and end-group-capturing effect significantly improved the flame retardancy of the copolymer, characterized by an UL-94 V-0 rating with great anti-dripping performance, 41% reduction in peak heat release rate and 50% reduction in total heat release. The room-temperature hydrogen bonding largely mitigated the deterioration of the chain symmetry and regularity caused by the incorporation of the monomer, thus resulting in substantial preservation of mechanical properties. Furthermore, the copolymer exhibited low dielectric properties and high heat resistance, thereby broadening its potential application domains. This work presented a novel flame-retardant-free strategy for achieving both flame retardancy and high performance in polymeric materials, meeting the increasingly stringent demands for environmental protection and safety.

A green and sustainable -COOH & -OH condensation solution polymerization method was hereby reported for FDCA-based polyesters to avoid discoloration and toxic solvents. First, taking poly(ethylene 2,5-furandicarboxylate) (PEF) as the representative of FDCA-based polyester, enabling good white appearance PEF with Mn=6.51×103 g mol-1 from FDCA and ethylene glycol in green solvent γ-valerolactone (GVL), catalyzed by 4-dimethylaminopyridine (DMAP) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC). Additionally, the molecular weight of PEF was rapidly improved (Mn >2.5×104 g mol-1) via remelting polycondensation within minutes, with the dispersity still kept relatively low dispersity (Đ<1.40). Importantly, the -COOH & -OH condensation solution polymerization method was successfully applied for the synthesis of various FDCA-based polyesters, including diols with varying carbon chain lengths (3 to 11 carbons) and cycloalkyl diols, especially the applicability of this method to diols containing C=C double bonds, which was found to exhibit low heat resistance. Lastly, assisting with 13C labeled 1,4-succinic acid and in-situ 13C-NMR, an in-depth study of the possible catalytic mechanism was proposed, by which, EDC activated FDCA, and then DMAP catalyzed it with diol to yield macromolecular chain of polyester. Overall, the results provided a green and sustainable strategy for the synthesis of FDCA-based polyesters.

The construction of materials with rapid electron transfer is considered an effective method for enhancing electrochemical activity in electroanalysis. It has been widely demonstrated that valence changes in transition metal ions can promote electron transfer and thus increase electrochemical activity. Recently, valence-variable transition metal oxides (TMOs) have shown popular application in electrochemical analysis by using their abundant valence state changes to accelerate electron transfer during electrochemical detection. In this review, we summarize recent research advances in valence changes of TMOs and their application in electrochemical analysis. This includes the definition and mechanism of valence change, the association of valence changes with electronic structure, and their applications in electrochemical detection, along with the use of density functional theory (DFT) to simulate the process of electron transfer during valence changes. Finally, the challenges and opportunities for developing and applying valence changes in electrochemical analysis are also identified.

Although conventional chemical copolymerization method has shown favorable results in improving certain performance of polymers, simultaneous improvement of overall properties is hardly achieved. Here, we reported a feasible method to fabricate high-performance polymers with great overall properties by simultaneously tailoring their chemical constitution and topological conformation. We designed and synthesized a novel functional monomer with a sidechain caged structure based on phosphorus chemistry, and prepared the corresponding aliphatic polyamide as a typical representative of thermoplastic synthetic polymers. The incorporation of a sidechain caged structure enhanced the chain entanglement of the resultant polyamide, thus improved the mechanical strength by 39% and largely enhanced the heat resistance. The great processability was basically uninfluenced due to the easy dissociation of the entanglement during processing, enabling the potentially wide application fields as both fibers and engineering plastics. Furthermore, based on the free radical scavenging effect of the phosphorus-based monomer, the flame retardancy of the resultant polyamide was significantly improved. In sight of these findings, this work provides a novel method for fabricating high-performance polymers for various applications.

The preparation of recyclable multifunctional biobased cross-linked polymers for different application environments and reducing dependence on petroleum products are important for sustainable development. Herein, we successfully synthesized a series of environmentally friendly, shape memory, adhesion, self-healing, and recyclable biobased polyester networks using 2,5-furandicarboxylic acid (FDCA) and 5,5 '-((dodecylazanediyl)bis(methylene))bis(furan-5,2-diyl))dimethanol (DoDM) derived from renewable materials by introducing reversible Diels-Alder bonds with the addition of bismaleimide (BMI). Profiting from the freely rotating difuran ring group in DoDM, the cross-linked network with tunable thermal and mechanical properties can be constructed and present fascinating versatility. A kinetic analysis suggests that the reaction follows second-order kinetics, and the calculated activation energy is 48.1 kJ/mol with an optimal temperature of 60 degrees C. Different cross-linking densities of PDoF/BMI networks result in glass transition temperatures varying from 19 to 47 degrees C, tensile moduli from 22 to 529 MPa, and elongations at break from 5 to 120%. The PDoF/BMI network has a good shape memory performance: it can be fixed to a temporary shape below T-g and restored to its original shape by heating above T-g, with a shape recovery rate of up to 98%. In addition, the PDoF/BMI 10:1 polymer network can be used as a solvent-free adhesive with strong adhesion to glass (3.1 +/- 0.5 kPa). The dynamic bond provides a self-healing response that can repair the surface scratch damage and contribute to 87% of the tensile stress recovery. Meanwhile, the PDoF/BMI film can be recovered after shredding, implying the good recyclability of the PDoF/BMI polymer. Therefore, the PDoF/BMI polymer, as a biobased multifunctional environmentally friendly material, has potential application prospects in a wide range of practical fields.

微塑料(MPs)对水生生态系统主要生产者微藻的生物效应及其相互作用,目前还没有得到足够的关注.为此以蛋白核小球藻为受试生物,考察聚对苯二甲酸乙二醇酯(PET,石油基塑料)及其替代物聚 2,5-呋喃二甲酸乙二醇酯(PEF,生物基塑料)两种 MPs 对微藻产生的生物效应,并进行比较.结果表明,PEF和PET MPs能够抑制微藻细胞生长及其体内叶绿素的积累,扰乱微藻的抗氧化平衡体系,对活性氧(ROS)的积累及抗氧化酶的活性具有诱导和促进作用.研究还发现,PEF和PET MPs会促进微藻胞外聚合物(EPS)的分泌,降低胞内大分子物质的含量;通过扫描电子显微镜发现许多微藻细胞黏附在粗糙的 MPs 表面形成异质聚集体.PEF和PET MPs对微藻的生物效应具有一定的差异性,尤其是 EPS的分泌方面,PEF MPs对 EPS分泌的促进作用大于 PET MPs 的;从侧面来看,生物基 PEF MPs 可能具备更好的生物降解性能.研究结果为不同来源(生物基或石油基)MPs 的生物效应研究提供了基础数据,为生物基 MPs环境风险评估提供了研究基础.

以2,5-呋喃二甲酸二甲酯(DMFD)、乙二醇(EG)为原料,原位添加扩链剂均苯四甲酸二酐(PMDA)、纳米二氧化钛(TiO2)、硅藻土(DE),以钛酸四丁酯为催化剂,采用酯交换-熔融缩聚法制备聚2,5-呋喃二甲酸乙二醇酯(PEF)/TiO2/DE复合材料.通过核磁共振波谱仪(NMR)、傅里叶变换衰减全反射红外光谱仪(ATR-FTIR)、X射线衍射仪(XRD)和热重分析仪(TGA)等技术手段对其结构、热学性能、力学性能、气体渗透性能及紫外屏蔽性能进行表征.结果表明,PEF/TiO2/DE复合材料被成功制备,且TiO2及DE均为物理掺杂.DE粒子在PEF/TiO2/DE复合材料内部分散良好.所有聚酯粉末为无定形聚集态结构.与PEF相比,PEF/TiO2/DE复合材料的5％质量损失温度(Td,5％)、分解速率最快温度(Tdmax)分别提升12.1 ℃和8.4 ℃.PEF/TiO2/DE复合材料的拉伸模量及抗冲击强度最高分别达到2657 MPa和3.2×104J/m2.纳米TiO2和DE的引入调控了 PEF/TiO2/DE复合材料对CO2、O2的渗透性,CO2屏障改善系数(BIFco2)由PEF/TiO2的3.02变为1.37～4.64,O2屏障改善系数(BIFO2)由PEF/TiO2的1.36变为0.7～2.07;此外,纳米Ti02的加入赋予PEF良好的紫外屏蔽性能:PEF/TiO2复合材料的紫外屏蔽率由PEF的45.38％提高至83.85％,提高了 85％,PEF/TiO2/DE复合材料的紫外屏蔽性能均大于84％.

Constructing micro cross-linking structures into molecular chains has demonstrated the ability to improve basic properties, such as mechanical strength and thermal stability, of thermoplastic polymers. However, this method has limitations when it comes to improving the functionality of polymers. Herein, we reported a multifunctional micro cross-linking network that improves not just mechanical strength but also flame retardancy, dielectric properties, battery performance, antistatic properties, etc. A novel phosphinamide-containing monomer was designed, synthesized, and copolymerized into the polymer chain of polyamide 6, a typical thermoplastic polymer. On the one hand, the micro cross-linking structure was successfully obtained through the amide interchange reaction between the side-chain phosphinamide groups and the main-chain amide groups, leading to a 23.7% improvement of tensile strength and largely maintained tensile toughness. On the other hand, the functional phosphorus groups showed an efficient free-radical-capturing effect during fire, endowing the copolymer with excellent flame retardancy at a low monomer content of 2 mol%. Additionally, the copolymer also possessed great spinnability, melt-crystallization performance, as well as dielectric property, antistatic property, and battery performance, enabling its potential in a wide variety of applications.

As a candidate of fossil-based poly(ethylene terephthalate) (PET), bio-based poly(ethylene 2,5-furandicarboxylate) (PEF) that could be converted from renewable resources has attracted attention from academia and industry. Here, we prepare a series of new type of PEF/TiO2 NWs composites from 2,5-furandicarboxylic acid (FDCA), ethylene glycol (EG), titanium dioxide nanowire (TiO2 NWs, diameter-100 nm, length-20 mu m) and dipentaerythritol (Di-PE) via in-situ polymerization. The TiO2 nanowires (0.5-10 wt%o based on PEF) and Di-PE (3 mol%o based on FDCA) were added as fillers and extenders. TiO2 nanowires were distributed in the PEF uniformly, shown by SEM. Compared with pure PEF, the Tg and thermal stability of all nanocomposites got improved. And the impact strength of nanocomposites could reach 60 kJ/m(2) in contrast to brittle pure PEF. The UV-A and blue-light shielding of nanocomposites increased from 53 % to 98 % and 28 % to 86 %, respectively, and the nanocomposites still maintained good gas barrier properties. Moreover, the antibacterial activity of nanocomposites against E. coli had increased to 98 %, better than that of the PEF/Ag NWs composites. By uniaxial pre-stretching, the tensile modulus and the elongation at break were improved obviously, from 1840 MPa to 5466 MPa and 4 % to 54 % respectively with pre-stretching ratio increasing. Compared to the PET/TiO2 NWs composites, the PEF/TiO2 NWs composites shows batter thermal property and mechanical property. The PEF/TiO2 NWs composites exhibit potential foreground in the packaging application.

Poly (ethylene 2,5-furandicarboxylate) (PEF) has attracted more attention due to its excellent properties and great potential to be the substitute of the petroleum-based polyethylene terephthalate (PET). However, the improvement of toughness and functionality from nano materials were limited. Here, we prepared novel PEF/TiO2 nanocomposites from dimethyl 2,5-furandicarboxylate (DMFD), ethylene glycol (EG), pyromellitic dianhydride (PMDA) and TiO2 nanoparticles via one-pot polycondensation. The optimized PMDA (5‰ mol/mol of DMFD), TiO2 (60 nm, 0.5-10‰ wt./wt. of PEF) or TiO2 (30 nm or 100 nm, 3‰) served as extender, fillers, and comparison, respectively. The Tgs (∼88 °C) and the thermal stability of all nanocomposites were higher than pure PEF. The crystallization rate of the nanocomposites (60 nm-TiO2, 3‰) was improved mostly, and its half-crystallization time (t1/2) decreased to 6.16 min at 160 °C. The impact strength of nanocomposites (60 nm-TiO2, 10‰) could reach to 52.2 × 103 J/m2. Interestingly, the ultraviolet and blue-light shielding of PEF/TiO2 nanocomposites increased from 45.4% to 93.5% and 21.5% to 74.3%, respectively. The antibacterial activity of nanocomposites against E. coli also increased to 83%. The maximum migration of Ti during 35 d was 1.82 µg/g (FDA and EU guidance level are 10 µg/g). PEF/TiO2 nanocomposites shown great potential in industrial production and application.

Bio-based plastics have been developed as alternative materials to solve the energy crisis brought by plastic production, but their impacts on soil ecosystems (e.g. plant and microorganisms) remain largely unknown. Here, we conducted study on the impacts of polyethylene 2,5-furan-dicarboxylate (PEF), a new bio-based plastic, on the plant-soil ecosystem, with comparison of fossil-based plastic polyethylene terephthalate (PET). Our investigation showed that, after 21 days exposure to microplastics (MPs) at doses of 0.5%, 1% and 2%, both PEF and PET MPs inhibited the growth of lettuce, where chlorophyll was found to be the most sensitive index. According to the comprehensive stress resistance indicators, PET MPs showed more severe phytotoxicity than PEF MPs. Although both PEF and PET MPs could inhibit soil enzyme activities, PET MPs exhibited significantly reduction on the diversity of rhizosphere soil bacterial community and changed the relative abundance of dominant species. Our study gave insights into the effects of PEF and PET MPs on the plant-soil system, where bio-based PEF MPs showed more friendly interaction with plant and soil than fossil-based PET MPs. Our results provided scientific data for risk assessment and useful information for the prospective application of bio-based plastics.

Transition metal oxides are widely used in electrochemical detection because of the promotion of redox of heavy metal ions (HMIs) by valence change behavior. However, it is challenging to favorably promote the valence change to achieve the improvement of detection sensitivity. Herein, a Mn3O4/g-C3N4 composite (named as MOCN) with small-sized of Mn3O4 and high proportion of Mn(II) and Mn(III) was prepared, which reveals an excellent performance on detecting mercury ion (Hg(II)). It is discovered that Mn3O4 becomes small in size and well disperses on g-C3N4, which solves the adverse effect of agglomeration and also lead to a good conductivity. And g-C3N4 can provide more adsorption sites to enhance the adsorption on Hg(II). Heterojunction is proved to form in MO-CN and thus accelerates electrons to flow from g-C3N4 to Mn3O4. This results in transforming Mn(IV) to Mn(II) and Mn(III) in Mn3O4, thereby promoting the cycle of Mn(II)/Mn(III)/Mn(IV) and furthermore facilitating the redox of Hg(II). Simultaneously, the obtained sensitivity (473.43 mu A mu M- 1 cm-2) and limit of detection (LOD, 0.003 mu M) are as expected. The nanocomposites and heterojunction based on transition metal oxide and 2D nanomaterials is promising to boost the detection of HMIs.

Producing aromatic poly(ester-ether)s from completely renewable feedstocks is almost inaccessible via existing ring-opening polymerization or melt polycondensation methods. Herein, we report a practical strategy to synthesize fully biobased poly(ester-ether)s in a one-pot/two-component manner via industrial melt polycondensation. The polymerization process was controlled by applying Sc(OTf)(3) as a catalyst and bio-based 2,5-furandicarboxylic acid and ethylene glycol as the substrate template to afford poly(ester-ether)s with a controlled oligoethylene glycol segment in the range from 10 to 92%. Studying the mechanism and model kinetics of Sc(OTf)(3)-catalyzed etherification reactions provided complete insights into the formation process and impetus of poly(ester-ether)s, validating that a "butterfly effect" occurred in the reaction process. In contrast to flexible conventional polyethers, computational studies revealed that the unique rigidity of the etherification moiety leads to superior thermal and mechanical properties of poly(ester-ether)s. This synthetic protocol demonstrates applicability and versatility, exemplified by using various bio-based diacids/diesters to synthesize a series of poly(ester-ether)s. We envisage that this work will improve the privileged position that renewable poly(ester-ether)s hold as functional materials and broaden their applicability in diverse fields.

The monomer PhDM with a particular structure was introduced into PEF to regulate the properties of the copolymer, especially the gas barrier and UV shielding properties, which is promising for food packaging applications.

A series of novel biobased polyesters are synthesized by introducing difuranyl monomers-bis-(hydroxymethylfurfuryl)amines (BHMFAs) and 2,5-furandicar-boxylate (FDCA) for thefirst time under mild condensationconditions, in which both FDCA and BHMFAs are derived fromthe biomass platform chemical 5-hydroxymethylfurfural. Thespecial structure of the polyesters, in which the structural repeatingunit contains three furan rings and alterable side chains (ethyl,heptyl, dodecyl, benzyl, and phenethyl groups), endows theircontrollable performance, conformation, and free volume. Theresults showed that all of the polyesters are amorphous, confirmedby the results of DSC, XRD, and density functional theory.Different side chains of the polyesters result inTgs varying from 3.5to 51.6 degrees C, tensile moduli from 3 to 551 MPa, and elongations at break from 13 to 1100%. Significantly, the polyester with phenethylas the side chain shields similar to 100% UV light. The polyester with benzyl as the side chain reduces gas permeability coefficients (PCO2andPO2) by approximately three times compared with poly (ethylene terephthalate) (PET), which can be well explained byfractional free volume calculation results from molecular dynamics simulation. In addition, the polyesters show high dielectricconstants (epsilon= 4.01-4.58) and maintain relatively low dielectric loss (tan delta= 0.023-0.043). This work provides strategies fordesigning and synthesizing biopolyesters with rigid toflexible structures, excellent UV shielding, gas barriers, and dielectric properties by varying the structure of the side chains and by introducing the difuran ring group