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1.
Macromol Rapid Commun ; 45(10): e2300734, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38361081

RESUMEN

Constructing good microphase separation structures by designing different polymer backbones and ion-conducting groups is an effective strategy for improving the ionic conductivity and chemical stability of anion exchange membranes (AEMs). In this study, a series of AEMs based on the poly(pentafluorophenylcarbazole) backbone grafted with different cationic groups are designed and prepared to construct well-defined microphase separation morphology and improve the trade-off between the properties of AEMs. Highly hydrophobic fluorinated backbone and alkyl spaces enhance phase separation and construct interconnected hydrophilic channels for anion transport. The ionic conductivity of the PC-PF-QA membrane is 123 mS cm-1 at 80 °C, and the ionic conductivity of the PC-PF-QA membrane decreased by only 6% after 960 h of immersion at 60 °C in 1 M NaOH aqueous solution. The maximum peak power density of the single cell based on PC-PF-QA is 214 mW cm-2 at 60 °C.


Asunto(s)
Carbazoles , Conductividad Eléctrica , Suministros de Energía Eléctrica , Carbazoles/química , Polímeros/química , Polímeros/síntesis química , Membranas Artificiales , Intercambio Iónico , Estructura Molecular , Halogenación , Aniones/química , Interacciones Hidrofóbicas e Hidrofílicas
2.
Macromol Rapid Commun ; 45(3): e2300502, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37996994

RESUMEN

Excessive swelling is one important factor that leads to high fuel permeability and limited operating concentration of methanol for proton exchange membranes. Herein, a collaborative strategy of main-chain and molecular-network engineering is applied to lower swelling ratio and improve methanol resistance for highly sulfonated polyimide. Two m-phenylenediamine monomers (4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine and 4,6-bis(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine) with tetrafluorostyrol groups are designed and synthesized. Two series of cross-linked sulfonated polyimides (CSPI-Ts, CSPI-Bs) are prepared from the two diamines, 4,4'-diaminostilbene-2,2'-disulfonic acid and 1,4,5,8-naphthalenetetracarboxylicdianhydride. The rigid main-chain structure is cornerstone for wet CSPI-Ts and CSPI-Bs remaining stable at elevated temperatures. The introduction of hydrophobic cross-linked network further improves their dimensional stability and methanol resistance. CSPI-Ts and CSPI-Bs show obviously improved performances containing high proton conductivity (121 ± 0.27-158 ± 0.35 S cm-1 ), low swelling ratio (9.6 ± 0.40%-16.1 ± 0.01%) and methanol permeability (4.14-7.69 × 10-7 cm2 s-1 ) at 80 °C. The direct methanol fuel cell (DMFC) is assembled from CSPI-T-10 with balanced properties, and it exhibits high maximum power density (PDmax ) of 82.3 and 72.6 mW cm-2 in 2 and 10 m methanol solution, respectively. The ratio of PDmax in 10 m methanol solution to the value in 2 m methanol solution is as high as 88%. The CSPI-T-10 is promising proton exchange membrane candidate for DMFC application.


Asunto(s)
Benceno , Metanol , Protones , Alcanosulfonatos , Diaminas
3.
Am J Cardiol ; 210: 58-64, 2024 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-37838070

RESUMEN

Oral anticoagulation with vitamin K antagonists is currently advised for a period of 3 months after surgical mitral valve repair, regardless of the rhythm status. The evidence supporting this recommendation is weak and recent studies have challenged the safety and efficacy of this recommendation. A systematic review of literature was conducted by searching PubMed, Embase, Web of Science, Emcare, and Cochrane Library databases for original publications comparing the efficacy and safety of oral anticoagulation with vitamin K antagonists to antiplatelet treatment early after mitral valve surgery in patients with no atrial fibrillation. Study end points included thromboembolic complications, bleeding complications and survival. A total of 5 studies, including 5,093 patients, met the inclusion criteria; 2,824 patients were included in the oral anticoagulation and 2,269 in the antiplatelet treatment group. Pooled analyses demonstrated no beneficial effect of oral anticoagulation on the incidence of thromboembolic complications (risk ratio 1.14, 95% confidence interval 0.76 to 1.70, p = 0.53, I2 = 8%). Moreover, oral anticoagulation did not result in a significantly increased risk of bleeding complications (risk ratio 0.89, 95% confidence interval 0.32 to 2.44, p = 0.81, I2 = 87%). When combining the efficacy and safety end points, no difference was observed between groups (risk ratio 1.01, 95% confidence interval 0.51 to 1.97, p = 0.99 I2 = 85%). Likewise, mortality did not differ between groups (risk ratio 0.89, 95% confidence interval 0.15 to 5.23, p = 0.90 I2 = 71%). Our results confirmed the safety but failed to confirm the efficacy of oral anticoagulation in patients who underwent mitral valve surgery. A randomized controlled trial would provide the evidence needed to support treatment recommendations.


Asunto(s)
Válvula Mitral , Tromboembolia , Humanos , Válvula Mitral/cirugía , Anticoagulantes , Hemorragia/inducido químicamente , Tromboembolia/epidemiología , Tromboembolia/etiología , Tromboembolia/prevención & control , Vitamina K , Administración Oral
4.
Polymers (Basel) ; 15(13)2023 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-37447498

RESUMEN

A series of epoxy resins containing various trifluoromethyl groups were synthesized and thermally cured with diaminodiphenylmethane (DDM) and aminophenyl sulfone (DDS). All epoxy resins exhibited excellent thermal stability with the glass transition temperatures of above 128 °C and 5% weight loss temperatures of above 300 °C. DDS-cured epoxy resins possessed higher thermal stability than that of DDM-cured epoxy resins, while DDM-cured epoxy resins showed better mechanical, dielectric, and hydrophobic properties. Additionally, DDM-cured epoxy resins with different locations and numbers of trifluoromethyl groups showed flexural strength in the range of 95.55~152.36 MPa, flexural modulus in the range of 1.71~2.65 GPa, dielectric constant in the range of 2.55~3.05, and water absorption in the range of 0.49~0.95%. These results indicate that the incorporation of trifluoromethyl pendant groups into epoxy resins can be a valid strategy to improve the dielectric and hydrophobic performance.

6.
Small ; 19(31): e2205291, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36635000

RESUMEN

Fabricating polymer electrolyte membranes (PEMs) simultaneously with high ion conductivity and selectivity has always been an ultimate goal in many membrane-integrated systems for energy conversion and storage. Constructing broader ion-conducting channels usually enables high-efficient ion conductivity while often bringing increased crossover of other ions or molecules simultaneously, resulting in decreased selectivity. Here, the ultra-small carbon dots (CDs) with the selective barriers are self-assembled within proton-conducting channels of PEMs through electrostatic interaction to enhance the proton conductivity and selectivity simultaneously. The functional CDs regulate the nanophase separation of PEMs and optimize the hydration proton network enabling higher-efficient proton transport. Meanwhile, the CDs within proton-conducting channels prevent fuel from permeating selectively due to their repelling and spatial hindrance against fuel molecules, resulting in highly enhanced selectivity. Benefiting from the improved conductivity and selectivity, the open-circuit voltage and maximum power density of the direct methanol fuel cell (DMFC) equipped with the hybrid membranes raised by 23% and 93%, respectively. This work brings new insight to optimize polymer membranes for efficient and selective transport of ions or small molecules, solving the trade-off of conductivity and selectivity.

7.
Artículo en Inglés | MEDLINE | ID: mdl-35328919

RESUMEN

As a common substance in production and life, phthalic acid esters (PAEs), the main component of plastics, have brought more and more serious problems to the environment. This study normalized the insulation, toxicity, and bioconcentration data of 13 PAEs to eliminate the dimensional coefficients of each index, and then used the comprehensive index method to calculate the comprehensive effect value of PAEs with three properties. The comprehensive effect value was used as the data source to construct the 3D-QSAR model of PAE molecular comprehensive effect. The DAP was selected as the target molecule, the distribution of each force field in the three-dimensional equipotential map was analyzed, and 30 molecular modification schemes were created. The constructed single-effect models of insulation, toxicity, and bioconcentration of PAEs and the scoring function module of DS software were used to evaluate the stability and environmental friendliness of PAE derivative molecules. Four PAE derivatives were screened for increased comprehensive effects, enhanced insulation, and reduced toxicity and bioconcentration. By calculating the binding energy of the target molecule and the derivative molecule with the degrading enzyme under different applied electric fields, it was found that the binding energy of DAP-1-NO2-2-CH2C6H5 decreases more than DAP does when there is an applied electric field, indicating that the degradation ability of degrading enzymes on PAE derivative molecules is reduced, which indirectly proves that the insulation is enhanced. The innovation of this paper lies in the insulation, toxicity, and bioenrichment data of PAEs being processed by mathematical method for the first time, and PAEs with high insulation, low toxicity, and low bioconcentration were designed by building a comprehensive model.


Asunto(s)
Ésteres , Ácidos Ftálicos , China , Ésteres/química , Ácidos Ftálicos/metabolismo , Plásticos/química , Relación Estructura-Actividad Cuantitativa
8.
Dent Mater ; 38(2): 281-293, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34955233

RESUMEN

OBJECTIVE: Although bisphenol Aglycidyl methacrylate (Bis-GMA) are widely used in the dental composite, its raw materials include the petroleum-based product bisphenol A (BPA) with high estrogenic activity (EA). In this study, two new BPA-free dimethacrylate monomers from bio-based material creosol were synthesized and evaluated. METHODS: The renewable bisphenol monomer 5, 5'-methylenedicreosol (BCF) was prepared from bio-based material creosol. By the human breast cancer cells (MCF-7 cells) proliferation assay, a risk assessment of BCF was performed to determine if BCF possessed reduced EA in comparison to BPA. Then, the novel monomers 5, 5'-methylenedicreosol diglycidyl ether diacrylate (BCF-EA) and 5, 5'-methylenedicreosol diglycidyl ether dimethacrylate (BCF-GMA) were synthesized from BCF with epichlorohydrin and (meth)acrylate. All products were investigated by 1H NMR and FT-IR spectra. The control resin was a mixture based on Bis-GMA and tri(ethyleneglycol) dimethacrylate (TEGDMA) with a weight ratio of 5:5 (5B5T). Similarly, experimental resin matrix was a mixture based on BCF-EA/TEGDMA (5E5T) and BCF-GMA/TEGDMA (5G5T). And their corresponding composites were then prepared with corresponding resin matrices and hybrid SiO2 (5E5TC, 5G5TC and 5B5TC). The properties of these composites were investigated according to the standard or referenced methods. Each sample was evaluated for double bond conversion (DC), shrinkage stress (SS) and volumetric polymerization shrinkage (VS). Water sorption (WS), water solubility (SL), mechanical properties and cytotoxicity were also measured. RESULTS: 1H NMR and FT-IR spectra confirmed the chemical structure of each monomer. EA test revealed that bio-based bisphenol monomer BCF as the precursor of BCF-EA and BCF-GMA showed lower EA than BPA. Cured resin matrix: Both 5E5T and 5G5T had nearly the same DC (p < 0.05), which was higher than 5B5T (p < 0.05); 5E5T and 5G5T had lower VS, SL and cytotoxicity than 5B5T (p < 0.05); mechanical properties of 5E5T and 5G5T were all better than those of 5B5T (p < 0.05). Cured composite: There was no significant difference in conversion (p < 0.05); 5E5TC and 5G5TC had significantly lower VS (p < 0.05); WS of 5E5TC and 5G5TC were similar (p < 0.05), but higher compared to 5B5TC (p < 0.05); 5E5TC and 5G5TC had the deeper depth of cure (p > 0.05); before water immersion, there was no significant difference in flexural strength between 5E5TC and 5G5TC (p > 0.05), and higher than 5B5TC (p < 0.05); 5E5TC and 5G5TC showed less cytotoxicity than 5B5TC (p < 0.05). SIGNIFICANCE: The new BPA-free di(meth)acrylates are promising photocurable dental monomers owning to bio-based raw material, high degree of conversion coupled with low curing shrinkage and good mechanical properties. Therefore, BCF-EA and BCF-GMA has a potential to be used as the substitution for Bis-GMA to prepare Bis-GMA-free dental composite.


Asunto(s)
Resinas Compuestas , Dióxido de Silicio , Compuestos de Bencidrilo , Bisfenol A Glicidil Metacrilato/química , Resinas Compuestas/química , Humanos , Ensayo de Materiales , Metacrilatos/química , Fenoles , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Espectroscopía Infrarroja por Transformada de Fourier
9.
ACS Appl Mater Interfaces ; 13(34): 40673-40684, 2021 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-34410701

RESUMEN

The approach to constructing proton transport channels via direct adjustments, including hydrophilia and analytical acid concentration in hydrophilic domains, has been proved to be circumscribed when encouraging the flatter hydrophilic-hydrophobic microphase separation structures and reducing conductivity activation energy. Here, we propose a constructive solution by regulating the polarity of hydrophobic domains, which indirectly varies the aggregation and connection of hydrophilic ion clusters during membrane formation, enabling orderly self-assembly and homogeneously distributed microphase structures. Accordingly, a series of comb-shaped polymers were synthesized with diversified optimization, and more uniformly distributed ion cluster lattices were subsequently observed using high-resolution transmission electron microscopy. Simultaneously, combining with density functional theory calculations, we analyzed the mechanism of membrane degradations caused by hydroxyl radical attacks. Experimental results demonstrated that, facilitated by proper molecule polarity, beneficial changes of bond dissociation energy could extend the membrane lifetime more than the protection from side chains near ether bonds, which were deemed to reduce the probability of attacks by the steric effect. With the optimal strategy chosen among various trials, the maximum power density of direct methanol fuel cell and H2/air proton exchange membrane fuel cell was enhanced to 95 and 485 mW cm-2, respectively.

10.
Biosci Rep ; 41(9)2021 09 30.
Artículo en Inglés | MEDLINE | ID: mdl-34369557

RESUMEN

In clinical practice, intestinal autologous diseases, ailments and organ transplants can cause severe congestive damage to the intestinal tract. However, after the etiological factor is gotten rid of and blood flow is free without any hinderance, further damage to the intestinal wall often occurs, causing other related organ dysfunctions. This ultimately results in intestinal congestion reperfusion injury (ICRI). When the structure and function of the intestine are destroyed, bacteria, metabolites and endotoxins in the intestinal tract perfuse and enter the portal vein through the already compromised intestinal mucosa, to the other organs via the liver. Nevertheless, this gives rise to further aggravation of the injury, and reperfusion injury syndrome occurs. ICRI is a very common complication encountered by clinicians, and its harm is more severe and serious as compared with that caused by ischemia-reperfusion. Quite a few number of studies on ICRI have been reported to date. The exact mechanism of the injury is still idiopathic, and effective treatment strategies are still limited. Based on recent studies, this article is aimed at reviewing the destruction, damage mechanisms resulting from ICRI to the intestinal anatomical sites and distant organs. It is geared towards providing new ideas for the prevention and therapeutic approaches of ICRI.


Asunto(s)
Enfermedades Intestinales/patología , Intestinos/irrigación sanguínea , Intestinos/patología , Daño por Reperfusión/patología , Circulación Esplácnica , Animales , Apoptosis , Bacterias/metabolismo , Traslocación Bacteriana , Microbioma Gastrointestinal , Humanos , Mediadores de Inflamación/metabolismo , Enfermedades Intestinales/metabolismo , Enfermedades Intestinales/microbiología , Enfermedades Intestinales/fisiopatología , Intestinos/metabolismo , Intestinos/microbiología , Pronóstico , Daño por Reperfusión/metabolismo , Daño por Reperfusión/microbiología , Daño por Reperfusión/fisiopatología , Transducción de Señal
11.
J Colloid Interface Sci ; 603: 408-417, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34197989

RESUMEN

The development of high-temperature supercapacitors highly relies on the explore of stable polymer electrolyte membranes (PEMs) with high ionic conductivities at high-temperature conditions. However, it is a challenge to achieve both high stability and high conductivity in a PEM at elevated temperatures. Herein, we report the fabrication of high-performance proton conductive PEMs suitable for high-temperature supercapacitors (HT-SCs), which is based on a post-assembly strategy to control the rearrangement of polymer networks in the PEMs. This strategy can create cross-linked PEMs with bicontinuous nanostructures, as well as highly stable and highly conductive features. Specifically, a series of bicontinuous PEMs are prepared by the controllable cross-linking of poly(ether-ether-ketone) and poly(4-vinylpyridine), followed by the inducement of phosphoric acid. These PEMs exhibit both a high proton conductivity of 70 mS cm-1 and a high modulus of 39.3 MPa at 150 â„ƒ, which can serve as high-performance electrolytes. The HT-SCs based on these PEMs display a specific capacitance of 138.0 F g-1 and a high capacitance retention of 80.0% after 2500 galvanostatic charge-discharge cycles at 150 â„ƒ, exhibiting excellent high-temperature capacitance and cycle stability. This post-assembly concept can provide a new route to design high-performance PEMs for HT-SC and other energy device applications.

12.
Dent Mater J ; 40(2): 422-430, 2021 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-33518690

RESUMEN

This study evaluated the effect of incorporating phosphorylated chitosan/amorphous calcium phosphate nanocomplex (Pchi/ACP) into an experimental light-cure composite resin on mechanical-chemical properties and human dentin remineralization. The results showed that the mechanical strength and contact angles of the resins decreased with the increase incorporation of Pchi/ACP. Release concentrations of calcium in saline solution were measured at different time points, showing the incorporation of Pchi/ACP significantly increased calcium release within 14 days, and kept steady thereafter. Finally, the demineralized dentin slabs treated with our resins for four weeks were characterized by SEM-EDS. Various amounts of apatite were formed on the dentin slabs which were treated with the resins containing Pchi/ACP, whereas no apatite was formed without Pchi/ACP. In conclusion, the Pchi/ACP-incorporating composite resin can be a promising dental material due to its favorable mechanical and remineralization properties.


Asunto(s)
Quitosano , Resinas Compuestas , Fosfatos de Calcio , Dentina , Humanos , Remineralización Dental
14.
ChemistryOpen ; 9(10): 1033-1045, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33101830

RESUMEN

The biodegradability of phtalic acid esters in marine and freshwater environments was characterized by their binding free energy with corresponding degrading enzymes. According to comprehensive biodegradation effects weights, the binding free energy values were converted into dimensionless efficacy coefficient using ratio normalization method. Then, considering comprehensive dual biodegradation effects value and the structural parameters of PAEs in both marine and freshwater environments, a 3D-QSAR pharmacophore model was constructed, five PAE derivatives (DBP-COOH, DBP-CHO, DBP-OH, DINP-NH2, and DINP-NO2) were screened out based on their environmental friendliness, functionality and stability. The prediction of biodegradation effects on five PAE derivatives by biodegradation models in marine and freshwater environment increased by 15.90 %, 15.84 %, 27.21 %, 12.33 %, and 8.32 %, and 21.57 %, 15.21 %, 20.99 %, 15.10 %, and 9.74 %, respectively. By simulating the photodegradation path of the PAE derivative molecular, it was found that DBP-OH can generate .OH and provides free radicals for the photodegradation of microplastics in the environment.


Asunto(s)
Diseño de Fármacos , Ésteres/química , Océanos y Mares , Ácidos Ftálicos/química , Ácidos Ftálicos/metabolismo , Agua Dulce , Modelos Moleculares , Conformación Molecular , Relación Estructura-Actividad Cuantitativa
15.
Polymers (Basel) ; 12(9)2020 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-32872093

RESUMEN

The addition of plasticizers makes plastics flammable, and thus, poses a potential risk to the environment. In previous researches, plasticizers with flame retardancy had been synthesized, but their eco-friendliness had not been tested or described. Thus, in this paper, eco-friendliness plasticizers with flame retardancy were designed based on phthalic acid esters (PAEs), which are known as common plasticizers and major plastic additives. For a comprehensive analysis, such as flammability, biotoxicity, and enrichment effects, 17 PAEs' comprehensive evaluation values were calculated based on the ideal point method. Further, a multi-effect three-dimensional quantitative structure-activity relationship (3D-QSAR) model of PAEs' flammability, biotoxicity and enrichment effects was constructed. Thus, 18 dimethyl phthalate (DMP) derivatives and 20 diallyl phthalate (DAP) derivatives were designed based on three-dimensional contour maps. Through evaluation of eco-friendliness and flammability, six eco-friendly PAE derivatives with flame retardancy were screened out. Based on contour maps analysis, it was confirmed that the introduction of large groups and hydrophobic groups was beneficial to the simultaneous improvement of PAEs' comprehensive effects, and multiple effects. In addition, the group properties were correlated significantly with improved degrees of the comprehensive effects of corresponding PAE derivatives, confirming the feasibility of the comprehensive evaluation method and modified scheme.

17.
Artículo en Inglés | MEDLINE | ID: mdl-32717867

RESUMEN

A phthalic acid ester's (PAEs) comprehensive biodegradability three-dimensional structure-activity relationship (3D-QSAR) model was established, to design environmentally friendly PAE derivatives, which could be simultaneously degraded by plasticizer-degrading bacteria, such as Burkholderia cepacia, Archaeoglobus fulgidus, and Pseudomonas aeruginosa. Only three derivatives of diethyl phthalate (DEP (DEP-27, DEP-28 and DEP-29)) were suited for their functionality and environmental friendliness, which had an improved stability in the environment and improved the characteristics (bio-toxicity, bioaccumulation, persistence, and long-range migration) of the persistent organic pollutants (POPs). The simulation inference of the microbial degradation path before and after DEP modification and the calculation of the reaction energy barrier exhibited the energy barrier for degradation being reduced after DEP modification and was consistent with the increased ratio of comprehensive biodegradability. This confirmed the effectiveness of the comparative molecular similarity index analysis (CoMSIA) model of the PAE's comprehensive biodegradability. In addition, a molecular dynamics simulation revealed that the binding of the DEP-29 derivative with the three plasticizer-degradation enzymes increased significantly. DEP-29 could be used as a methyl phthalate derivative that synergistically degrades with microplastics, providing directional selection and theoretical designing for plasticizer replacement.


Asunto(s)
Archaeoglobus fulgidus , Burkholderia cepacia , Pseudomonas aeruginosa , Biodegradación Ambiental , Ésteres , Ácidos Ftálicos , Plásticos , Relación Estructura-Actividad Cuantitativa
18.
ACS Appl Mater Interfaces ; 11(35): 31899-31908, 2019 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-31407896

RESUMEN

A novel ionic liquid-impregnated metal-organic-framework (IL@NH2-MIL-101) was prepared and introduced into sulfonated poly(arylene ether ketone) with pendent carboxyl groups (SPAEK) as the nanofiller for achieving hybrid proton exchange membranes. The nanofiller was anchored in the polymeric matrix by the formation of amido linkage between the pendent carboxyl group attached to the molecule chain of SPAEK and amino group belonging to the inorganic framework, thus leading to the enhancement in mechanical properties and dimensional stability. Besides, the hybrid membrane (IL@MOF-1) exhibits an enhanced proton conductivity up to 0.184 S·cm-1 because of the incorporation of ionic liquid in the nanocages of NH2-MIL-101. Moreover, the special structure of NH2-MIL-101 contributes to a low leakage of ionic liquid so as to retain the stable proton conductivity of hybrid membranes under fully hydrated conditions. Furthermore, as a result of a cross-linked structure formed by inorganic nanofiller, the IL@MOF-1 hybrid membrane shows a lower methanol permeability (7.53 × 10-7 cm2 s-1) and superior selectivity (2.44 × 105 S s cm-3) than the pristine SPAEK membrane. Especially, IL@MOF-1 performs high single-cell efficiency with a peak power density of 37.5 mW cm-2, almost 2.3-fold to SPAEK. Electrochemical impedance spectroscopy and scanning electron microscopy indicated that the nanofiller not only contributed to faster proton transfer but also resulted in a tighter bond between the membrane and catalyst. Therefore, the incorporation of IL@NH2-MIL-101 to prepare the hybrid membrane is proven to be suitable for application in direct methanol fuel cells.

19.
RSC Adv ; 9(14): 7975-7983, 2019 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-35521211

RESUMEN

Anion exchange membranes based on side-chain-type quarternized poly(ether ether ketone)s (QPEEKs), containing different hetero-cycloaliphatic quaternary ammonium groups, were prepared via a multi-step procedure, including polycondensation with a monomer containing pendant methylphenyl groups, bromomethylation, and followed by quaternization with 1-methylpyrrolidine (MPY), 1-methylpiperidine (MPRD), 1-methylimidazole (MIDZ) and N-methyl morpholine (MMPH), respectively. The properties of these membranes were then compared with the properties of conventional quarternized poly(ether ether ketone)s containing benzyltrimethylammonium (QPEEK-TMA). Model compounds, QMPY, QMPRD, QMIDZ and QMMPH, were synthesized and used to quantitatively compare the alkaline stability of hetero-cycloaliphatic quaternary ammonium groups using 1H NMR. The results of this study indicated that the alkaline stability of all these model compounds is in the order of QMPY > QMPRD > QTMA > QMIDZ > QMMPH. These QPEEKs membranes display superior thermal, dimensional and mechanical stability. QPEEK-TMA, QPEEK-MPY and QPEEK-MPRD exhibit higher hydroxide conductivities and lower activation energies than QPEEK-MIDZ and QPEEK-MMPH. Furthermore, after exposure to 1 M NaOH at 60 °C for 24 days, QPEEK-MPY and QPEEK-MPRD demonstrated a loss in hydroxide conductivity of 28.5% and 33.4%, respectively. Both values were lower than that of QPEEK-TMA (37.7%). Therefore, among these side-chain-type QPEEKs membranes, QPEEK-MPY and QPEEK-MPRD, containing benzylmethylpyrrolidinium and benzylmethylpiperidinium as cation head-groups, are promising AEM materials for fuel cell construction.

20.
ACS Appl Mater Interfaces ; 10(9): 7963-7973, 2018 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-29439561

RESUMEN

Novel side-chain-type sulfonated poly(arylene ether ketone) (SNF-PAEK) containing naphthalene and fluorine moieties on the main chain was prepared in this work, and a new amino-sulfo-bifunctionalized metal-organic framework (MNS, short for MIL-101-NH2-SO3H) was synthesized via a hydrothermal technology and postmodification. Then, MNS was incorporated into a SNF-PAEK matrix as an inorganic nanofiller to prepare a series of organic-inorganic hybrid membranes (MNS@SNF-PAEK-XX). The mechanical property, methanol resistance, electrochemistry, and other properties of MNS@SNF-PAEK-XX hybrid membranes were characterized in detail. We found that the mechanical strength and methanol resistances of these hybrid membranes were improved by the formation of an ionic cross-linking structure between -NH2 of MNS and -SO3H on the side chain of SNF-PAEK. Particularly, the proton conductivity of these hybrid membranes increased obviously after the addition of MNS. MNS@SNF-PAEK-3% exhibited the proton conductivity of 0.192 S·cm-1, which was much higher than those of the pristine membrane (0.145 S·cm-1) and recast Nafion (0.134 S·cm-1) at 80 °C. This result indicated that bifunctionalized MNS rearranged the microstructure of hybrid membranes, which could accelerate the transfer of protons. The hybrid membrane (MNS@SNF-PAEK-3%) showed a better direct methanol fuel cell performance with a higher peak power density of 125.7 mW/cm2 at 80 °C and a higher open-circuit voltage (0.839 V) than the pristine membrane.

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