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1.
J Am Chem Soc ; 146(23): 16340-16347, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38820231

RESUMO

A stable aluminum tris(dithiolene) triradical (3) was experimentally realized through a low-temperature reaction of the sterically demanding lithium dithiolene radical (2) with aluminum iodide. Compound 3 was characterized by single-crystal X-ray diffraction, UV-vis and EPR spectroscopy, SQUID magnetometry, and theoretical computations. The quartet ground state of triradical 3 has been unambiguously confirmed by variable-temperature continuous wave EPR experiments and SQUID magnetometry. Both SQUID magnetometry and broken-symmetry DFT computations reveal a small doublet-quartet energy gap [ΔEDQ = 0.18 kcal mol-1 (SQUID); ΔEDQ = 0.14 kcal mol-1 (DFT)]. The pulsed EPR experiment (electron spin echo envelop modulation) provides further evidence for the interaction of these dithiolene-based radicals with the central aluminum nucleus of 3.

2.
Small ; : e2401995, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38818678

RESUMO

Upgrading thermosetting polymer waste and harvesting unwanted electromagnetic energy are of great significance in solving environmental pollution and energy shortage problems. Herein, inspired by the glass-blowing art, a spontaneous, controllable, and scalable strategy is proposed to prepare hollow carbon materials by inner blowing and outside blocking. Specifically, hierarchically neuron-like hollow carbon materials (HCMSs) with various sizes are fabricated from melamine-formaldehyde sponge (MS) waste. Benefiting from the synergistic of the hollow "cell body" and the connected "protrusions" networks, HCMSs reveal superior electromagnetic absorption performance with a strong reflection loss of -54.9 dB, electromagnetic-heat conversion ability with a high conversion efficiency of 34.4%, and efficient energy storage performance in supercapacitor. Furthermore, a multifunctional device integrating electromagnetic-heat-electrical energy conversion is designed, and its feasibility is proved by experiments and theoretical calculations. The integrated device reveals an output voltage of 34.5 mV and a maximum output power of 0.89 µW with electromagnetic radiation for 60 s. This work provides a novel solution to recycle polymer waste, electromagnetic energy, and unwanted thermal energy.

3.
Small ; : e2401429, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38808805

RESUMO

Plastics serve as an essential foundation in contemporary society. Nevertheless, meeting the rigorous performance demands in advanced applications and addressing their end-of-life disposal are two critical challenges that persist. Here, an innovative and facile method is introduced for the design and scalable production of polycarbonate, a key engineering plastic, simultaneously achieving high performance and closed-loop chemical recyclability. The bisphenol framework of polycarbonate is strategically adjusted from the low-bond-dissociation-energy bisphenol A to high-bond-dissociation-energy 4,4'-dihydroxydiphenyl, in combination with the incorporation of polysiloxane segments. As expected, the enhanced bond dissociation energy endows the polycarbonate with an extremely high glow-wire flammability index surpassing 1025 °C, a 0.8 mm UL-94 V-0 rating, a high LOI value of 39.2%, and more than 50% reduction of heat and smoke release. Furthermore, the π-π stacking interactions within biphenyl structures resulted in a significant enhancement of mechanical strength by as more as 37.7%, and also played a positive role in achieving a lower dielectric constant. Significantly, the copolymer exhibited outstanding closed-loop chemical recyclability, allowing for facile depolymerization into bisphenol monomers and the repolymerized copolymer retains its high heat and fire resistance. This work provides a novel insight in the design of high-performance and closed-loop chemical recyclable polymeric materials.

4.
Small ; : e2400980, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38545991

RESUMO

Polyolefin separators are the most commonly used separators for lithium batteries; however, they tend to shrink when heated, and their Li+ transference number (t Li +) is low. Metal-organic frameworks (MOFs) are expected to solve the above problems due to their high thermal stability, abundant pore structure, and open metal sites. However, it is difficult to prepare high-porosity MOF-based membranes by conventional membrane preparation methods. In this study, a high-porosity free-standing MOF-based safety separator, denoted the BCM separator, is prepared through a nano-interfacial supramolecular adhesion strategy. The BCM separator has a large specific surface area (450.22 m2 g-1) and porosity (62.0%), a high electrolyte uptake (475 wt%), and can maintain its morphology at 200 °C. The ionic conductivity and t Li + of the BCM separator are 1.97 and 0.72 mS cm-1, respectively. Li//LiFePO4 cells with BCM separators have a capacity retention rate of 95.07% after 1100 cycles at 5  C, a stable high-temperature cycling performance of 300 cycles at 80 °C, and good capacity retention at -40 °C. Li//NCM811 cells with BCM separators exhibit significantly improved rate performance and cycling performance. Pouch cells with BCM separators can work at 120 °C and have good safety at high temperature.

5.
Cell Commun Signal ; 22(1): 93, 2024 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-38302971

RESUMO

BACKGROUND: Physical exercise directly stretching the peripheral nerve promotes nerve regeneration; however, its action mechanism remains elusive. Our present study aimed to investigate the effects of mechanosensitive channel of large conductance (MscL) activated by mechanical stretching on the cultured Schwann cells (SCs) and explore the possible mechanism. METHODS: Primary SCs from neonatal mice at 3-5 days of age were derived and transfected with the lentivirus vector expressing a mutant version of MscL, MscL-G22S. We first detected the cell viability and calcium ion (Ca2+) influx in the MscL-G22S-expressing SCs with low-intensity mechanical stretching and the controls. Proteomic and energy metabolomics analyses were performed to investigate the comprehensive effects of MscL-G22S activation on SCs. Measurement of glycolysis- and oxidative phosphorylation-related molecules and ATP production were respectively performed to further validate the effects of MscL-G22S activation on SCs. Finally, the roles of phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway in the mechanism of energy metabolism modulation of SCs by MscL-G22S activation was investigated. RESULTS: Mechanical stretching-induced MscL-G22S activation significantly increased the cell viability and Ca2+ influx into the SCs. Both the proteomic and targeted energy metabolomics analysis indicated the upregulation of energy metabolism as the main action mechanism of MscL-G22S-activation on SCs. MscL-G22S-activated SCs showed significant upregulation of glycolysis and oxidative phosphorylation when SCs with stretching alone had only mild upregulation of energy metabolism than those without stimuli. MscL-G22S activation caused significant phosphorylation of the PI3K/AKT/mTOR signaling pathway and upregulation of HIF-1α/c-Myc. Inhibition of PI3K abolished the MscL-G22S activation-induced upregulation of HIF-1α/c-Myc signaling in SCs and reduced the levels of glycolysis- and oxidative phosphorylation-related substrates and mitochondrial activity. CONCLUSION: Mechanical stretching activates MscL-G22S to significantly promote the energy metabolism of SCs and the production of energic substrates, which may be applied to enhance nerve regeneration via the glia-axonal metabolic coupling.


Assuntos
Proteínas Proto-Oncogênicas c-akt , Transdução de Sinais , Camundongos , Animais , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Regulação para Cima , Proteômica , Proteínas Proto-Oncogênicas c-myc/metabolismo , Glicólise , Células de Schwann/metabolismo , Fosfatidilinositol 3-Quinase/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Estresse Oxidativo , Mamíferos/metabolismo
6.
Biomacromolecules ; 25(6): 3795-3806, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38781116

RESUMO

Biodegradable polymers with shape memory effects (SMEs) offer promising solutions for short-term medical interventions, facilitating minimally invasive procedures and subsequent degradation without requiring secondary surgeries. However, achieving a good balance among desirable SMEs, mechanical performance, degradation rate, and bioactivities remains a significant challenge. To address this issue, we established a strategy to develop a versatile biodegradable polyurethane (PPDO-PLC) with tunable hierarchical structures via precise chain segment control. Initial copolymerization of l-lactide and ε-caprolactone sets a tunable Tg close to body temperature, followed by block copolymerization with poly(p-dioxanone) to form a hard domain. This yields a uniform microphase-separation morphology, ensuring robust SME and facilitating the development of roughly porous surface structures in alkaline environments. Cell experiments indicate that these rough surfaces significantly enhance cellular activities, such as adhesion, proliferation, and osteogenic differentiation. Our approach provides a methodology for balancing biodegradability, SMEs, three-dimensional (3D) printability, and bioactivity in materials through hierarchical structure regulation.


Assuntos
Poliuretanos , Poliuretanos/química , Poliuretanos/farmacologia , Proliferação de Células/efeitos dos fármacos , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Animais , Porosidade , Adesão Celular/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Camundongos , Poliésteres/química , Diferenciação Celular/efeitos dos fármacos , Lactonas/química , Lactonas/farmacologia , Humanos , Caproatos/química , Dioxanos/química , Polímeros
7.
Nano Lett ; 23(21): 9841-9850, 2023 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-37737087

RESUMO

To mimic natural photonic crystals having color regulation capacities dynamically responsive to the surrounding environment, periodic assembly structures have been widely constructed with response materials. Beyond monocomponent materials with stimulus responses, binary and multiphase systems generally offer extended color space and complex functionality. Constructing a rule for predicting response sensitivity can provide great benefits for the tailored design of intelligently responsive photonic materials. Here, we elucidate mathematical relationships between the response sensitivity of dynamically structural-color changes and the location distances of photonic co-phases in three-dimensional Hansen space that can empirically express the strength of their interaction forces, including dispersion force, polarity force, and hydrogen bonding. Such an empirical rule is proven to be applicable for some typical alcohols, acetone, and acetic acid regardless of their molecular structures, as verified by angle resolution spectroscopy, in situ infrared spectroscopy, and molecular simulation. The theoretical method we demonstrate provides rational access to custom-designed responsive structural coloration.

8.
Angew Chem Int Ed Engl ; 63(26): e202405912, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38655622

RESUMO

Although many approaches have been proposed to recycling waste epoxy resin (EP), the separation of mixed degraded products remains a challenge due to their similar structures. To address this, we present a catalytic oxidation strategy that enables mild degradation of EP and in situ separation of degraded products through supramolecular interactions. The oxidative degradation relies on FeIV=O radicals with strong oxidizing properties, which are generated from the electron transfer of FeCl2 with reaction reagents. As the FeIV=O radicals attacked the C-N bonds of EP, EP was broken into fragments rich in active functional groups. Meanwhile, the FeIV=O radicals were reduced to iron ions that can coordinate with the carboxyl groups on the fragments. As a result, the degraded products with different carboxyl content can be effortlessly separated into liquid and solid phase by coordinating with the catalyst. The success of this work lays the foundation for high-value application of degraded products and provides new design ideas for recycling waste plastics with complex compositions.

9.
Angew Chem Int Ed Engl ; 63(9): e202314859, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38224179

RESUMO

Liquid crystal actuators conventionally undergo shape changes across an order-disorder phase transition between liquid crystal (LC) and isotropic phases. In this study, we introduce an innovative Liquid Crystal Polymer (LCP) actuator harnessing an order-order LC phase transition mechanism. The LCP film is easily stretchable within the LC phase, facilitated by the π-π stacking of phenyl groups serving as robust physical crosslinking points, and thereby transforms to a stable monodomain structure. The resultant monodomain LCP actuator shows a distinctive reversible dynamic shape change, exhibiting extension followed by contraction along the LC director on cooling. The extension is propelled by the reversible smectic C to smectic A phase transition, and the contraction is attributed to the re-entry to the smectic C phase from smectic A phase. Thermal annealing temperature determines this peculiar dynamic shape change, which occurs during both heating and cooling processes. This pivotal attribute finds manifestation in gripper and flower-shaped actuators, adeptly executing grabbing and releasing as well as blooming and closure motions within a single thermal stimulation. In essence, our study introduces an innovative approach to the realm of LCP actuators, ushering in a new avenue for the design and fabrication of versatile and dynamically responsive LCP actuators.

10.
Angew Chem Int Ed Engl ; : e202407510, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38774971

RESUMO

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high-value and high-volume long chain (C10-C20) saturated dicarboxylic acids in high carbon yield of 85.9% over cobalt-doped MCM-41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short-chain (C4-C10) to long-chain ones (C10-C20) through changing cobalt loading of MCM-41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one-step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids.

11.
J Am Chem Soc ; 145(10): 5592-5612, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36876997

RESUMO

Carbenes have evolved from transient laboratory curiosities to a robust, diverse, and surprisingly impactful ligand class. A variety of different carbenes have significantly contributed to the development of low-oxidation state main group chemistry. This Perspective focuses upon advances in the chemistry of carbene complexes containing main group element cores in the formal oxidation state of zero, including their diverse synthetic strategies, unusual bonding and structural motifs, and utility in transition metal coordination chemistry and activation of small molecules.

12.
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.

13.
Chemistry ; 29(65): e202302258, 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-37603856

RESUMO

The 1 : 2 reaction of the imidazole-based dithiolate (2) with GeCl2 • dioxane in THF/TMEDA gives 3, a TMEDA-complexed dithiolene-based germylene. Compound 3 is converted to monothiolate-complexed (5) and N-heterocyclic carbene-complexed (7) germanium(II) dithiolene complexes via Lewis base ligand exchange. A bis-dithiolene-based germylene (8), involving a 3c-4e S-Ge-S bond, has also been synthesized through controlled hydrolysis of 7. The bonding nature of 3, 5, and 8 was investigated by both experimental and theoretical methods.

14.
BMC Neurol ; 23(1): 1, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36597054

RESUMO

BACKGROUND: Anti-IgLON5 disease is a rare chronic autoimmune-mediated tauopathy, featured by the sleep disturbance. Several studies have described its clinical characteristics, however, the simultaneous occurrence of anti-IgLON5 disease and rectal cancer has not been reported. We described an unusual entity of anti-IgLON5 disease complicated with rectal cancer. CASE PRESENTATION: A 76-year-old man initially presented with slurred speech and limb tremors, followed by epileptic-like seizures, lethargy, and sleep apnea. IgG anti-IgLON5 antibodies were positive in both serum and cerebrospinal fluid. The patient responded well to the treatment of plasma exchange and a pulse and gradual reduction of steroids therapy. When the oral steroids started, mycophenolate mofetil was added. Two months later, the patient had bloody stools and pathological-confirmed moderately differentiated adenocarcinoma of the rectum. CONCLUSIONS: Whereas sleep disturbance is the most common feature in patients with anti-IgLON5 disease, our case presented with slurred speech and limb tremors. Anti-IgLON5 disease complicated with rectal cancer is very rare. Tumor screening should be considered in patients with anti-IgLON5 disease to investigate the association between tumor and this disease.


Assuntos
Doença de Hashimoto , Parassonias , Neoplasias Retais , Apneia Obstrutiva do Sono , Transtornos do Sono-Vigília , Masculino , Humanos , Idoso , Tremor , Doença de Hashimoto/complicações , Apneia Obstrutiva do Sono/complicações , Transtornos do Sono-Vigília/etiologia , Neoplasias Retais/complicações
15.
J Biochem Mol Toxicol ; 37(11): e23452, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37417536

RESUMO

Diabetes mellitus (DM), becomes a main public health issue worldwide due to the rapid increase in DM patient numbers. The dysfunction of endothelial progenitor cells (EPCs) in DM patients plays a critical role in endothelial repair and the progression of DM-related vascular complications. Loxenatide is an a glucagon-like peptide 1 receptor agonist, which is used to control glycemic in type 2 diabetes patients. However, the role of Loxenatide in EPCs remains to be investigated. EPCs were isolated, characterized, and treated with Loxenatide, high-glucose, or 3-TYP. quantitative real-time polymerase chain reaction, flow cytometry, western blot, and cell counting kit-8 assay were employed to validate the expression of gene and protein expressions and cell viability, respectively. Application of Seahorse XFp to measure oxygen consumption and mitochondrial membrane potential (MMP) were measured by Seahorse XFp and MMP assay. Loxenatide attenuated high-glucose-induced reactive oxygen species (ROS) production and mitochondrial-dependent apoptosis of EPCs in a concentration-dependent manner. The EPC mitochondrial respiration dysfunction induced by high glucose was also repressed by the loxenatide treatment. The protection effect of Loxenatide on EPCs against high-glucose was applied by activating the sirtuin 3 (SIRT3)/Foxo3 signaling pathway. We demonstrated the regulatory role of Loxenatide in mitochondrial dysfunction and apoptosis of EPCs. We elucidated that Loxenatide protects EPC from high-glucose-induced apoptosis via ROS-mediated mitochondrial pathway through the SIRT3/Foxo3 signing pathway. This may provide a new therapeutical target for the treatment of DM-related vascular complications.


Assuntos
Diabetes Mellitus Tipo 2 , Células Progenitoras Endoteliais , Sirtuína 3 , Humanos , Células Progenitoras Endoteliais/metabolismo , Sirtuína 3/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Transdução de Sinais , Apoptose , Glucose/farmacologia , Glucose/metabolismo , Mitocôndrias/metabolismo
16.
Exp Cell Res ; 416(1): 113149, 2022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35405116

RESUMO

BACKGROUND: Long non-coding RNAs (lncRNAs) have emerged as novel players in cancer metabolism. lncRNA small nucleolar RNA host gene 7 (SNHG7) plays an oncogenic role in prostate cancer (PCa). However, the role and mechanism of SNHG7 in PCa metabolism remain largely undefined. METHODS: A cohort of 30 PCa tumors and their counterparts were collected. qRT-PCR was employed to detect target gene expression and RNA stability. CCK-8 assay was used to assess cell viability. N6-methyladenosine (m6A) level was measured by a commercial kit. Cell glycolysis was evaluated by measuring glucose uptake, lactate, ATP production and Extracellular acidification rate (ECAR). Bioinformatics analysis and RNA immunoprecipitation (RIP) assay were used to verify the interactions among SNHG7, serine/arginine-rich splicing factor 1 (SRSF1) and c-Myc. RESULTS: SNHG7 and c-Myc were highly expressed in PCa tissues and cells. Methyltransferase-like 3 (METTL3)-mediated m6A modification of SNHG7 and enhanced its stability. Silencing of SNHG7 suppressed proliferation and glycolysis in PCa cells. Mechanistically, SNHG7 regulated c-Myc via interacting with SRSF1. Gain- and loss-of function experiments revealed that SNHG7 promoted glycolysis via SRSF1/c-Myc axis in PC-3 and DU-145 cells. CONCLUSION: METTL3-stabilized lncRNA SNHG7 accelerates glycolysis in PCa via SRSF1/c-Myc axis and inspires the understanding of m6A roles in lncRNA metabolism and tumor progression.


Assuntos
MicroRNAs , Neoplasias da Próstata , RNA Longo não Codificante , Carcinogênese/genética , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica/genética , Glicólise/genética , Humanos , Masculino , Metiltransferases/genética , MicroRNAs/genética , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Fatores de Processamento de Serina-Arginina/genética , Fatores de Processamento de Serina-Arginina/metabolismo
17.
BMC Pulm Med ; 23(1): 468, 2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-37996853

RESUMO

BACKGROUND: We analyzed the clinical characteristics of children with plastic bronchitis (PB) caused by Mycoplasma pneumoniae (MP) and explored its risk factors. METHODS: We prospectively analyzed clinical data of children with MP pneumonia (MPP) treated with fiberoptic bronchoscopy (FB). Patients were classified into a PB and non-PB group. General information, clinical manifestations, laboratory tests, results of computed tomography scan, and FB findings were compared between groups. We conducted statistical analysis of risk factors for developing PB. RESULTS: Of 1169 children who had MPP and were treated with FB, 133 and 1036 were in the PB and non-PB groups, respectively. There were no significant differences in sex, age, and incident season between groups (P > 0.05). The number of children in the PB group decreased during the COVID-19 pandemic. Compared with children in the non-PB group, those in the PB group had longer duration of hospitalization, increased levels of neutrophil (N), C-reactive protein (CRP), procalcitonin (PCT), D-dimer, lactate dehydrogenase (LDH), alanine transaminase (ALT) and aspartate transaminase (AST); lower levels of lymphocyte (L) and platelet (PLT); and higher incidence of lack of appetite, decreased breath sounds, single lobar infiltrate, pleural effusion, pericardial effusion, mucosal erosion and/or necrosis, and bronchial embolization. L levels and pleural effusion were identified as risk factors in multivariate logistic regression. CONCLUSIONS: Children with PB caused by MPP had a strong and local inflammatory response. L levels and pleural effusion were independent risk factors of PB with MPP in children. Our findings will help clinicians identify potential PB in pediatric patients for early and effective intervention.


Assuntos
Bronquite , Derrame Pleural , Pneumonia por Mycoplasma , Criança , Humanos , Mycoplasma pneumoniae , Pandemias , Estudos Retrospectivos , Pneumonia por Mycoplasma/complicações , Pneumonia por Mycoplasma/epidemiologia , Pneumonia por Mycoplasma/tratamento farmacológico , Fatores de Risco , Bronquite/epidemiologia
18.
Angew Chem Int Ed Engl ; 62(51): e202312638, 2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-37759361

RESUMO

Although a variety of dynamic covalent bonds have been successfully used in the development of diverse sustainable thermosetting polymers and their composites, solving the trade-off between recovery efficiency and comprehensive properties is still a major challenge. Herein, a "one-stone-two-birds" strategy of lower rotational energy barrier (Er ) phosphate-derived Diels-Alder (DA) cycloadditions was proposed for easily recyclable carbon fiber (CF)-reinforced epoxy resins (EPs) composites. In such a strategy, the phosphate spacer with lower Er accelerated the segmental mobility and dynamic DA exchange reaction for network rearrangement to achieve high-efficiency repairing, reprocessing of the EPs matrix and its composites and rapid nondestructive recycling of CF; meanwhile, incorporating phosphorus-based units especially reduced their fire hazards. The resulting materials simultaneously showed excellent thermal/mechanical properties, superb fire safety and facile recyclability, realizing the concept of recycling for high-performance thermosetting polymers and composites. This strategy is of great significance for understanding and enriching the molecular connotation of DA chemistry, making it potentially applicable to the design and development of a wide range of dynamic covalent adaptable materials toward practical cutting-edge-tech applications.

19.
Angew Chem Int Ed Engl ; 62(52): e202314448, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37938175

RESUMO

A novel in situ chemical upcycling strategy for plastic waste is proposed by the customized diphenylacetylene monomer with dual photo-response. That is, diphenylacetylene reactive monomers are in situ inserted into the macromolecular chain of polyethylene terephthalate (PET) plastics/fibers through one-pot transesterification of slight-depolymerization and re-polymerization. On the one hand, the diphenylacetylene group absorbs short-wave high-energy UV rays and then releases long-wave low-energy harmless fluorescence. On the other hand, the UV-induced photo-crosslinking reaction among diphenylacetylene groups produces extended π-conjugated structure, resulting in a red-shift (due to decreased HOMO-LUMO separation) in the UV absorption band and locked crosslink points between PET chains. Therefore, with increasing UV exposure time, the upcycled PET plastics exhibit reverse enhanced UV resistance and mechanical strength (superior to original performance), instead of serious UV-photodegradation and damaged performance. This upcycling strategy at oligomer-scale not only provides a new idea for traditional plastic recycling, but also solves the common problem of gradual degradation of polymer performance during use.

20.
J Am Chem Soc ; 144(36): 16325-16331, 2022 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-36037279

RESUMO

A carbene-stabilized dithiolene zwitterion (3) activates ammonia, affording 4• and 5, through both single-electron transfer (SET) and hydrogen atom transfer (HAT). Reaction products were characterized spectroscopically and by single-crystal X-ray diffraction. The mechanism of the formation of 4• and 5 was probed by experimental and computational methods. This discovery is the first example of metal-free ammonia activation via HAT.


Assuntos
Amônia , Hidrogênio , Transporte de Elétrons , Hidrogênio/química , Metano/análogos & derivados
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