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1.
Small ; 20(5): e2306274, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37759380

RESUMO

Efficient electrocatalysts capable of operating continuously at industrial ampere-level current densities are crucial for large-scale applications of electrocatalytic water decomposition for hydrogen production. However, long-term industrial overall water splitting using a single electrocatalyst remains a major challenge. Here, bimetallic polyphthalocyanine (FeCoPPc)-anchored Ru nanoclusters, an innovative electrocatalyst comprising the hydrogen evolution reaction (HER) active Ru and the oxygen evolution reaction (OER) active FeCoPPc, engineered for efficient overall water splitting are demonstrated. By density functional theory calculations and systematic experiments, the electrocatalytic coenhancement effect resulting from unique charge redistribution, which synergistically boosts the HER activity of Ru and the OER activity of FeCoPPc by optimizing the adsorption energy of intermediates, is unveiled. As a result, even at a large current density of 2.0 A cm-2 , the catalyst exhibits low overpotentials of 220 and 308 mV, respectively, for HER and OER. It exhibits excellent stability, requiring only 1.88 V of cell voltage to achieve a current density of 2.0 A cm-2 in a 6.0 m KOH electrolyte at 70 °C, with a remarkable operational stability of over 100 h. This work provides a new electrocatalytic coenhancement strategy for the design and synthesis of electrocatalyst, paving the way for industrial-scale overall water splitting applications.

2.
Small ; 19(36): e2302132, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37127874

RESUMO

Ultrathin 2D porous carbon-based materials offer numerous fascinating electrical, catalytic, and mechanical properties, which hold great promise in various applications. However, it remains a formidable challenge to fabricate these materials with tunable morphology and composition by a simple synthesis strategy. Here, a facile one-step self-flowering method without purification and harsh conditions is reported for large-scale fabrication of high-quality ultrathin (≈1.5 nm) N-doped porous carbon nanosheets (NPC) and their composites. It is demonstrated that the layered tannic/oxamide (TA/oxamide) hybrid is spontaneously blown, exfoliated, bloomed, in situ pore-formed, and aromatized during pyrolysis to form flower-like aggregated NPC. This universal one-step self-flowering system is compatible with various precursors to construct multiscale NPC-based composites (Ru@NPC, ZnO@NPC, MoS2 @NPC, Co@NPC, rGO@NPC, etc.). Notably, the programmable architecture enables NPC-based materials with excellent multifunctional performances, such as microwave absorption and hydrogen evolution. This work provides a facile, universal, scalable, and eco-friendly avenue to fabricate functional ultrathin porous carbon-based materials with programmability.

3.
Int J Mol Sci ; 23(19)2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36232352

RESUMO

To compare the different actions of the two representative transition metal cations of Co2+ and Ni2+ in layered double hydroxides (LDHs), CoAl-LDH and NiAl-LDH intercalated with CO32- were synthesized, and the chemical structures, microstructures, and surface areas thereof were successfully characterized. Then, the two LDHs were utilized as flame retardants and smoke suppressants for silicone foam (SiF). The densities, flame retardancy, smoke suppression, thermal stabilities, and compressive strengths of the two SiF/LDHs nanocomposites were investigated. The introduction of LDHs slightly decreased the density of SiF due to the catalytic actions of Co and Ni during the foaming process of SiF. With respect to the flame retardancy, the addition of only 1 phr of either CoAl-LDH or NiAl-LDH could effectively improve the limiting oxygen index of SiF from 28.7 to 29.6%. Based on the results of vertical flame testing and a cone calorimeter test, the flame retardancy and fire safety of the SiF were effectively enhanced by the incorporation of LDHs. In addition, owing to the good catalytic action and large specific surface area (NiAl-LDH: 174.57 m2 g-1; CoAl-LDH: 51.47 m2 g-1), NiAl-LDH revealed higher efficiencies of flame retardancy and smoke suppression than those of CoAl-LDH. According to the results of energy-dispersive X-ray spectroscopy, Co and Ni participated in the formation of protective char layers, which inhibited the release of SiO2 into the gas phase. Finally, the influences on the thermal decomposition and compressive strength for SiF resulting from the addition of LDHs are discussed.


Assuntos
Retardadores de Chama , Fumaça , Cátions , Hidróxidos/química , Oxigênio , Dióxido de Silício , Silicones
4.
Cancer Sci ; 112(10): 4365-4376, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34252262

RESUMO

A substantial proportion of prostatic adenocarcinoma (PRAD) patients experience biochemical failure (BCF) after radical prostatectomy (RP). The immune microenvironment plays a vital role in carcinogenesis and the development of PRAD. This study aimed to identify a novel immune-related gene (IRG)-based signature for risk stratification and prognosis of BCF in PRAD. Weighted gene coexpression network analysis was carried out to identify a BCF-related module in a discovery cohort of patients who underwent RP at the Massachusetts General Hospital. The median follow-up time was 70.32 months. Random forest and multivariate stepwise Cox regression analyses were used to identify an IRG-based signature from the specific module. Risk plot analyses, Kaplan-Meier curves, receiver operating characteristic curves, univariate and multivariate Cox regression analyses, stratified analysis, and Harrell's concordance index were used to assess the prognostic value and predictive accuracy of the IRG-based signature in the internal discovery cohort; The Cancer Genome Atlas database was used as a validation cohort. Tumor immune estimation resource database analysis and CIBERSORT algorithm were used to assess the immunophenotype of PRAD. A novel IRG-based signature was identified from the specific module. Five IRGs (BUB1B, NDN, NID1, COL4A6, and FLRT2) were verified as components of the risk signature. The IRG-based signature showed good prognostic value and predictive accuracy in both the discovery and validation cohorts. Infiltrations of various immune cells were significantly different between low-risk and high-risk groups in PRAD. We identified a novel IRG-based signature that could function as an index for assessing tumor immune status and risk stratification in PRAD.


Assuntos
Adenocarcinoma/genética , Redes Reguladoras de Genes , Antígenos HLA/genética , Neoplasias da Próstata/genética , Adenocarcinoma/imunologia , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Proteínas de Ciclo Celular/genética , Estudos de Coortes , Colágeno Tipo IV/genética , Seguimentos , Perfilação da Expressão Gênica , Marcadores Genéticos , Humanos , Imunidade Celular , Imunofenotipagem , Estimativa de Kaplan-Meier , Masculino , Glicoproteínas de Membrana/genética , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Valor Preditivo dos Testes , Prognóstico , Antígeno Prostático Específico/sangue , Prostatectomia , Neoplasias da Próstata/imunologia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/cirurgia , Proteínas Serina-Treonina Quinases/genética , Curva ROC , Análise de Regressão , Medição de Risco , Falha de Tratamento , Microambiente Tumoral/imunologia , Proteínas Supressoras de Tumor/genética
5.
Zhonghua Nan Ke Xue ; 27(6): 489-498, 2021 Jun.
Artigo em Zh | MEDLINE | ID: mdl-34914287

RESUMO

OBJECTIVE: To identify the key genes associated with the pathogenesis of PCa using the bioinformatics approach for a deeper insight into the molecular mechanisms underlying the development and progression of PCa. METHODS: The microarray datasets GSE70770, GSE32571 and GSE46602 were downloaded from the Gene Expression Omnibus (GEO) database, and differentially expressed genes (DEG) in the normal prostate tissue and PCa were identified with the GEO2R tool, followed by functional enrichment analysis. A protein-protein interaction (PPI) network of DEGs was constructed by STRING and visualized with the Cytoscape software. RESULTS: A total of 235 DEGs were identified, including 61 up-regulated and 174 down-regulated genes, which were mainly enriched in focal adhesion kinase (FAK), ECM-receptor interaction, and other signaling pathways. From the PPI network were screened out 12 highly connected hub genes, including MYH11, TPM1, TPM2, SMTN, MYL9, VCL, ACTG1, CNN1, CALD1, ACTC1, MYLK and SORBS1, which were shown by hierarchical cluster analysis to be capable of distinguishing prostate cancer from non-cancer tissue. CONCLUSIONS: A total of 235 DEGs and 12 hub genes were identified in this study, which may contribute to a further understanding of the molecular mechanisms of the development and progression of PCa, and provide new candidate targets for the diagnosis and treatment of the malignancy.


Assuntos
Biologia Computacional , Neoplasias da Próstata , Humanos , Masculino , Neoplasias da Próstata/genética
6.
Plant Biotechnol J ; 17(2): 397-409, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-29992702

RESUMO

Morella rubra, red bayberry, is an economically important fruit tree in south China. Here, we assembled the first high-quality genome for both a female and a male individual of red bayberry. The genome size was 313-Mb, and 90% sequences were assembled into eight pseudo chromosome molecules, with 32 493 predicted genes. By whole-genome comparison between the female and male and association analysis with sequences of bulked and individual DNA samples from female and male, a 59-Kb region determining female was identified and located on distal end of pseudochromosome 8, which contains abundant transposable element and seven putative genes, four of them are related to sex floral development. This 59-Kb female-specific region was likely to be derived from duplication and rearrangement of paralogous genes and retained non-recombinant in the female-specific region. Sex-specific molecular markers developed from candidate genes co-segregated with sex in a genetically diverse female and male germplasm. We propose sex determination follow the ZW model of female heterogamety. The genome sequence of red bayberry provides a valuable resource for plant sex chromosome evolution and also provides important insights for molecular biology, genetics and modern breeding in Myricaceae family.


Assuntos
Evolução Molecular , Genoma de Planta/genética , Myrica/genética , Mapeamento Cromossômico , Flores/genética , Flores/crescimento & desenvolvimento , Flores/fisiologia , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/fisiologia , Marcadores Genéticos/genética , Anotação de Sequência Molecular , Myrica/crescimento & desenvolvimento , Myrica/fisiologia , Especificidade de Órgãos , Melhoramento Vegetal
7.
Macromol Rapid Commun ; 38(23)2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29083104

RESUMO

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: "ionic aggregation," "smart self-cross-linking," and "rearrangement at high temperatures." Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier.


Assuntos
Polietilenotereftalatos/química , Polímeros/química
8.
Chemistry ; 21(2): 682-90, 2015 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-25399735

RESUMO

A new nanocomposite, poly(aniline-co-diphenylamine-4-sulfonic acid)/graphene (PANISP/rGO), was prepared by means of an in situ oxidation copolymerization of aniline (ANI) with diphenylamine-4-sulfonic acid (SP) in the presence of graphene oxide, followed by the chemical reduction of graphene oxide using hydrazine hydrate as a reductant. The morphology and structure of PANISP/rGO were characterized by field-emission (FE) SEM, TEM, X-ray photoelectron spectroscopy (XPS), Raman, FTIR, and UV/Vis spectra. The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The PANISP/rGO nanocomposite showed a nanosized structure, with sulfonic polyaniline nanoarrays coated homogeneously on the surface of graphene nanosheets. This special structure of the nanocomposite also facilitates the enhancement of the electrochemical performance of the electrodes. The PANISP/rGO nanocomposite exhibits a specific supercapacitance up to 1170 F g(-1) at the current density of 0.5 A g(-1) . The as-prepared electrodes show excellent supercapacitive performance because of the synergistic effects between graphene and the sulfonic polyaniline copolymer chains.

9.
BMC Urol ; 15: 90, 2015 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-26320076

RESUMO

BACKGROUND: The NIMA-related kinase 2 (NEK2) is a serine/threonine kinase that is involved in regulation of centrosome duplication and spindle assembly during mitosis. Dysregulation of these processes causes chromosome instability and aneuploidy, which are hallmark changes of many solid tumors. However, whether aberrant expression of NEK2 is associated with outcome of prostate cancer (PCa) patients remains to be determined. METHODS: Expression of NEK2 in human PCa cells and primary PCa tissues was assessed by quantitative RT-PCR. Expression of NEK2 in human PCa cells was depleted with siRNA. Effects of the depletion on cell proliferation, survival, and tumorigenicity were assessed both in vitro with cell cultures and in vivo with subcutaneous implantation of xenografts. In silico analyses of the online Taylor dataset were carried out to determine whether the expression level of NEK2 correlated with the clinicopathological characteristics of prostate cancer. RESULTS: Compared with benign human prostatic epithelial cells and tissues, the expression of NEK2 was elevated in human PCa cells and primary PCa tissues. Depleting NEK2 expression inhibited human PCa cell proliferation in vitro and xenograft growth in vivo. Expression level of NEK2 in PCa positively correlated with the Gleason score and pathologic stage of the patient. CONCLUSION: The results suggest that overexpression of NEK2 has the potential to serve as a biomarker for PCa prognosis. Further validation with large sample pool is warrant.


Assuntos
Biomarcadores Tumorais/metabolismo , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteínas Serina-Treonina Quinases/metabolismo , Idoso , Animais , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Nus , Quinases Relacionadas a NIMA , Prognóstico , Reprodutibilidade dos Testes , Medição de Risco/métodos , Sensibilidade e Especificidade , Regulação para Cima
10.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(10): 2906-10, 2015 Oct.
Artigo em Zh | MEDLINE | ID: mdl-26904842

RESUMO

Spectral Modulation Polarization Measurement technology (SMPM) is a new type of polarization modulation technology, with an achromatic /4 retarder, a multiple-order retarder and a polarizer the polarization information of incident light can be encoded into the spectral dimension, sinusoidal which amplitude scales with the degree of the linear polarization and phase scales with the angle of the linear polarization can be acquired directly. With a dedicated algorithm for the modulated spectrum, we can get degree and angle of the linear polarization, spectral information and radiation information of the target. This paper expounds the basic principle of SMPM and concrete implementation scheme is proposed. Demodulation algorithm is designed before experimental platform are set up. Experiment which verified the correctness on the SMPM has carried on. The experimental results show the correctness and feasibility of SMPM. Compared with traditional polarization modulate techniques no moving parts and electronic components are including in this scheme. It's also has the advantages of compact and low mass. We can get all the polarization information through one single measurement rather than get Stokes parameters for further calculations. This study provides a new kind of technological approaches for the development of new space polarization detecting sensor.

11.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(4): 1129-33, 2015 Apr.
Artigo em Japonês | MEDLINE | ID: mdl-26197616

RESUMO

The main disadvantages of traditional spectral polarization imaging system are: complex structure, with moving parts, low throughput. A novel method of spectral polarization imaging system is discussed, which is based on static polarization intensity modulation combined with Savart polariscope interference imaging. The imaging system can obtain real-time information of spectral and four Stokes polarization messages. Compared with the conventional methods, the advantages of the imaging system are compactness, low mass and no moving parts, no electrical control, no slit and big throughput. The system structure and the basic theory are introduced. The experimental system is established in the laboratory. The experimental system consists of reimaging optics, polarization intensity module, interference imaging module, and CCD data collecting and processing module. The spectral range is visible and near-infrared (480-950 nm). The white board and the plane toy are imaged by using the experimental system. The ability of obtaining spectral polarization imaging information is verified. The calibration system of static polarization modulation is set up. The statistical error of polarization degree detection is less than 5%. The validity and feasibility of the basic principle is proved by the experimental result. The spectral polarization data captured by the system can be applied to object identification, object classification and remote sensing detection.

12.
Int J Biol Macromol ; 269(Pt 2): 132135, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38719000

RESUMO

Here, a novel multifunctional coating containing bio-based phytic acid (PA), L-glutamic acid (L-Glu), and trimesoyl chloride (TMC) is constructed by a simple soaking strategy, giving cotton fabrics excellent flame retardancy, washability, and antibacterial properties. The coating layer on the cotton surface was prepared via the electrostatic and hydrogen bonding between PA and L-Glu, accompanied by the interface polymerization between PA, L-Glu, and TMC. Among them, the limiting oxygen index value of the treated cotton fabrics (C2 and C2-TMC) was as high as 40 %. During the vertical flammability test, both C2 and C2-TMC cotton showed self-extinguished behavior with a short damaged length (≤50 mm). Remarkably, the LOI of C2-TMC sustained a high value (30 %) even after 300 laundering cycles, maintaining its self-extinguishing behavior in the vertical combustion test. Additionally, in the cone calorimetry test, peak heat release rate and total heat release of treated cotton were lower than control cotton. Surprisingly, after 30 or 60 laundering cycles, the C2-TMC cotton exhibited excellent antibacterial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans due to the continuous exposure of PA and L-Glu. Moreover, the coating layer on the cotton surface had little impact on the mechanical properties and feel of the fabric.


Assuntos
Fibra de Algodão , Retardadores de Chama , Ácido Fítico , Ácido Fítico/química , Ácido Fítico/farmacologia , Aminoácidos/química , Candida albicans/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/farmacologia , Antibacterianos/química , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Têxteis , Testes de Sensibilidade Microbiana
13.
ACS Appl Mater Interfaces ; 16(15): 19519-19528, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38580622

RESUMO

The inherent flammability of most polymeric materials poses a significant fire hazard, leading to substantial property damage and loss of life. A universal flame-retardant protective coating is considered as a promising strategy to mitigate such risks; however, simultaneously achieving high transparency of the coatings remains a great challenge. Here, inspired by the moth eye effect, we designed a nanoporous structure into a protective coating that leverages a hydrophilic-hydrophobic interactive assembly facilitated by phosphoric acid protonated amino siloxane. The coating demonstrates robust adhesion to a diverse range of substrates, including but not limited to fabrics, foams, paper, and wood. As expected, its moth-eye-inspired nanoporous structure conferred a high visible light transparency of >97% and water vapor transmittance of 96%. The synergistic effect among phosphorus (P), nitrogen (N), and silicon (Si) largely enhanced the char-forming ability and restricted the decomposition of the coated substrates, which successfully endowed the coating with high fire-fighting performance. More importantly, for both flexible and rigid substrates, the coated samples all possessed great mechanical properties. This work provides a new insight for the design of protective coatings, particularly focusing on achieving high transparency.

14.
Nat Commun ; 15(1): 2726, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38548723

RESUMO

Polymeric materials, rich in carbon, hydrogen, and oxygen elements, present substantial fire hazards to both human life and property due to their intrinsic flammability. Overcoming this challenge in the absence of any flame-retardant elements is a daunting task. Herein, we introduce an innovative strategy employing catalytic polymer auto-pyrolysis before combustion to proactively release CO2, akin to possessing responsive CO2 fire extinguishing mechanisms. We demonstrate that potassium salts with strong nucleophilicity (such as potassium formate/malate) can transform conventional polyurethane foam into materials with fire safety through rearrangement. This transformation results in the rapid generation of a substantial volume of CO2, occurring before the onset of intense decomposition, effectively extinguishing fires. The inclusion of just 1.05 wt% potassium formate can significantly raise the limiting oxygen index of polyurethane foam to 26.5%, increase the time to ignition by 927%, and tremendously reduce smoke toxicity by 95%. The successful application of various potassium salts, combined with a comprehensive examination of the underlying mechanisms, underscores the viability of this strategy. This pioneering catalytic approach paves the way for the efficient and eco-friendly development of polymeric materials with fire safety.

15.
Mater Horiz ; 11(4): 978-987, 2024 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-38112580

RESUMO

Smart and dynamic electromagnetic interference (EMI) shielding materials possess a remarkable capacity to modify their EMI shielding abilities, rendering them invaluable in various civil and military applications. However, the present response mechanism of switch-type EMI shielding materials is slightly restricted, as it primarily depends on continuous pressure induction, thereby resulting in concerns regarding their durability and reliability. Herein, for the first time, we demonstrate a novel method for achieving solvent-responsive, reversible switching, and robust EMI shielding capabilities using a controlled proton-reservoir ordered gel. The gel contains polyaniline (PANI) and sodium alginate (SA). Initially, SA acts as a proton reservoir for PANI in an aqueous system, enhancing the doping level of PANI and improving its electrical conductivity. Additionally, PANI and SA chains respond to diverse polar solvents, such as water, acetonitrile, ethanol, n-hexane, and air, inducing distinct conformations that affect the degree of PANI conjugation and electron migration along the chains. This process is reversible and non-destructive to the polymer chain, ensuring the effective and uncompromised performance of the EMI shielding switch. We can achieve precise and reversible tuning (on/off) of EMI shielding with different effectiveness levels by manipulating the solvents within the framework. This work opens a new solvent-stimuli avenue for the development of EMI shielding materials with reliable and intelligent on/off switching capabilities.

16.
Int J Biol Macromol ; 273(Pt 2): 132811, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38825282

RESUMO

Atmospheric drying method for fabricating aerogels is considered the most promising way for casting aerogels on a large scale. However, the organic solvent exchange, remaining environmental pollution risk, is a crucial step in mitigating the impact of surface tension during the atmospheric drying process, especially for wet gel formed through the alkoxy-derived sol-gel process, such as melamine-formaldehyde resin (MF) aerogel. Herein, a tough polymer-assisted in situ polymerization was proposed to fabricate MF resin aerogel with a combination of mechanical toughness and strength, enabling it to withstand the capillary force during water evaporation. The monolithic MF resin aerogel through the sol-gel method can be directly prepared without additional network strengthening or organic solvent exchange. The resulting MF resin aerogel exhibits a homogeneous as well as hierarchical structure with macropores and mesopores (~6 µm and ~5 nm), high compressive modulus of 31.8 MPa, self-extinguishing property, and high-temperature thermal insulation with 97 % heat decrease for butane flame combustion. This work presents a straightforward and environmentally friendly method for fabricating MF resin aerogels with nanostructures and excellent performance in open conditions, exhibiting various applications.

17.
Mater Horiz ; 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38742392

RESUMO

Polyurethane (PU) foams, pivotal in modern life, face challenges suh as fire hazards and environmental waste burdens. The current reliance of PU on potentially ecotoxic halogen-/phosphorus-based flame retardants impedes large-scale material recycling. Here, our demonstrated controllable catalytic cracking strategy, using cesium salts, enables self-evolving recycling of flame-retardant PU. The incorporation of cesium citrates facilitates efficient urethane bond cleavage at low temperatures (160 °C), promoting effective recycling, while encouraging pyrolytic rearrangement of isocyanates into char at high temperatures (300 °C) for enhanced PU fire safety. Even in the absence of halogen/phosphorus components, this foam exhibits a substantial increase in ignition time (+258.8%) and a significant reduction in total smoke release (-79%). This flame-retardant foam can be easily recycled into high-quality polyol under mild conditions, 60 °C lower than that for the pure foam. Notably, the trace amounts of cesium gathered in recycled polyols stimulate the regenerated PU to undergo self-evolution, improving both flame-retardancy and mechanical properties. Our controllable catalytic cracking strategy paves the way for the self-evolutionary recycling of high-performance firefighting materials.

18.
Chemosphere ; 311(Pt 2): 137047, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36336017

RESUMO

With the high integration of electronic products in our daily life, high-performance epoxy resins (EP) with excellent flame retardancy, smoke suppression, and mechanical strength are highly desired for applications. In this study, copper organophosphate nanosheets were evenly grown on the surface of graphene oxide (GO) via a self-assembly process based on coordination bonding and electrostatic interactions. The resultant nanohybrid endowed EP with satisfactory flame retardant effect and improved mechanical properties. Incorporating functionalized nanosheets of merely 1 wt% loading, the impact strength of the EP nanocomposites improved by 147% when compared to 1% EP-GO. Additionally, the nanosheets inhibited the smoke and heat release of EP, and the limiting oxygen value of EP-EGOPC reached ∼29%. The mechanism analysis verified that the existence of organophosphate and copper-containing components associated with the physical barrier of GO promoted the hybrid aromatization of the char layer, thereby improving the fire safety of epoxy matrix. This research offers a new interfacial method for designing functional nanosheets with good interface compatibility and high flame-retardant efficiency in polymers.

19.
Chemosphere ; 342: 140184, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37716559

RESUMO

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers.


Assuntos
Resinas Epóxi , Retardadores de Chama , Dióxido de Silício , Cápsulas , Catálise , Fósforo
20.
J Colloid Interface Sci ; 640: 864-876, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36907147

RESUMO

Epoxy resins (EPs) are known for their durability, strength, and adhesive properties, which make them a versatile and popular material for use in a variety of applications, including chemical anticorrosion, small electronic devices, etc. However, EP is highly flammable due to its chemical nature. In this study, phosphorus-containing organic-inorganic hybrid flame retardant (APOP) was synthesized by introducing 9, 10-dihydro-9-oxa-10­phosphaphenathrene (DOPO) into cage-like octaminopropyl silsesquioxane (OA-POSS) via Schiff base reaction. The improved flame retardancy of EP was achieved by combining the physical barrier of inorganic Si-O-Si with the flame-retardant capability of phosphaphenanthrene. EP composites containing 3 wt% APOP passed the V-1 rating with a value of LOI of 30.1% and showed an apparent reduction in smoke release. Additionally, the combination of the inorganic structure and the flexible aliphatic segment in the hybrid flame retardant provides EP with molecular reinforcement, while the abundance of amino groups facilitates a good interface compatibility and outstanding transparency. Accordingly, EP containing 3 wt% APOP increased in tensile strength, impact strength, and flexural strength by 66.0 %, 78.6 %, and 32.3 %, respectively. The EP/APOP composites had a bending angle lower than 90°, and their successful transition to a tough material highlights the potential of this innovative combination of the inorganic structure and the flexible aliphatic segment. In addition, the relevant flame-retardant mechanism revealed that the APOP promoted the formation of a hybrid char layer containing P/N/Si for EP and produced phosphorus-containing fragments during combustion, showing flame-retardant effects in both condensed and vapor phases. This research offers innovative solutions for reconciling flame retardancy & mechanical performances and strength & toughness for polymers.

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