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1.
Membranes (Basel) ; 13(9)2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37755192

RESUMO

In this paper, a cobalt (Co)-chelated polynaphthalene imine (Co-PNIM) was calcined to become an oxygen reduction reaction (ORR) electrocatalyst (Co-N-C) as the cathode catalyst (CC) of an anion exchange membrane fuel cell (AEMFC). The X-ray diffraction pattern of CoNC-1000A900 illustrated that the carbon matrix develops clear C(002) and Co(111) planes after calcination, which was confirmed using high-resolution TEM pictures. Co-N-Cs also demonstrated a significant ORR peak at 0.8 V in a C-V (current vs. voltage) curve and produced an extremely limited reduction current density (5.46 mA cm-2) comparable to commercial Pt/C catalysts (5.26 mA cm-2). The measured halfway potential of Co-N-C (0.82 V) was even higher than that of Pt/C (0.81 V). The maximum power density (Pmax) of the AEM single cell upon applying Co-N-C as the CC was 243 mW cm-2, only slightly lower than that of Pt/C (280 mW cm-2). The Tafel slope of CoNC-1000A900 (33.3 mV dec-1) was lower than that of Pt/C (43.3 mV dec-1). The limited reduction current density only decayed by 7.9% for CoNC-1000A900, compared to 22.7% for Pt/C, after 10,000 redox cycles.

2.
Chemistry ; 29(34): e202300760, 2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37060215

RESUMO

A continuous flow methodology for the facile and high-yielding synthesis of the porphyrin-based self-assembled organic cage, P12 L24 is reported, along with the serendipitous discovery of a kinetic product, P9 L18 cage, which has been characterized by MALDI-TOF MS, NMR, and AFM analysis. A theoretical study suggests a tricapped trigonal prismatic geometry for P9 L18 . Unlike P12 L24 , P9 L18 is unstable and readily decomposes into monomers and small oligomers. While the batch synthesis produces only the thermodynamic product P12 L24 , the continuous flow process generates not only the thermodynamic product but also kinetic products, such as P9 L18 , illustrating the advantages of the continuous flow process for the synthesis of self-assembled cages and the exploration of new non-equilibrium assemblies.

3.
Polymers (Basel) ; 15(8)2023 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-37112101

RESUMO

Aromatic polyimide has good mechanical properties and high-temperature resistance. Based on this, benzimidazole is introduced into the main chain, and its intermolecular (internal) hydrogen bond can increase mechanical and thermal properties and electrolyte wettability. Aromatic dianhydride 4,4'-oxydiphthalic anhydride (ODPA) and benzimidazole-containing diamine 6,6'-bis [2-(4-aminophenyl)benzimidazole] (BAPBI) were synthesized by means of a two-step method. Imidazole polyimide (BI-PI) was used to make a nanofiber membrane separator (NFMS) by electrospinning process, using its high porosity and continuous pore characteristics to reduce the ion diffusion resistance of the NFMS, enhancing the rapid charge and discharge performance. BI-PI has good thermal properties, with a Td5% of 527 °C and a dynamic mechanical analysis Tg of 395 °C. The tensile strength of the NFMS increased from 10.92MPa to 51.15MPa after being hot-pressed. BI-PI has good miscibility with LIB electrolyte, the porosity of the film is 73%, and the electrolyte absorption rate reaches 1454%. That explains the higher ion conductivity (2.02 mS cm-1) of NFMS than commercial one (0.105 mS cm-1). When applied to LIB, it is found that it has high cyclic stability and excellent rate performance at high current density (2 C). BI-PI (120 Ω) has a lower charge transfer resistance than the commercial separator Celgard H1612 (143 Ω).

4.
Polymers (Basel) ; 15(4)2023 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-36850199

RESUMO

In order to yield more Co(II), 2,6-diaminopyridine (DAP) was polymerized with 4,4-methylene diphenyl diisocyanates (MDI) in the presence of Co(II) to obtain a Co-complexed polyurea (Co-PUr). The obtained Co-PUr was calcined to become Co, N-doped carbon (Co-N-C) as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). High-resolution transmission electron microscopy (HR-TEM) of Co-N-C indicated many Co-Nx (Co covalent bonding with several nitrogen) units in the Co-N-C matrix. X-ray diffraction patterns showed that carbon and cobalt crystallized in the Co-N-C catalysts. The Raman spectra showed that the carbon matrix of Co-N-C became ordered with increased calcination temperature. The surface area (dominated by micropores) of Co-N-Cs also increased with the calcination temperature. The non-precious Co-N-C demonstrated comparable electrochemical properties (oxygen reduction reaction: ORR) to commercial precious Pt/C, such as high on-set and half-wave voltages, high limited reduction current density, and lower Tafel slope. The number of electrons transferred in the cathode was close to four, indicating complete ORR. The max. power density (Pmax) of the single cell with the Co-N-C cathode catalyst demonstrated a high value of 227.7 mWcm-2.

5.
Journal of Gastric Cancer ; : 315-327, 2023.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-1000902

RESUMO

Purpose@#Oxaliplatin, a component of the capecitabine plus oxaliplatin (XELOX) regimen, has a more favorable toxicity profile than cisplatin in patients with advanced gastric cancer (GC). However, oxaliplatin can induce sensory neuropathy and cumulative, dose-related toxicities. Thus, the capecitabine maintenance regimen may achieve the maximum treatment effect while reducing the cumulative neurotoxicity of oxaliplatin. This study aimed to compare the survival of patients with advanced GC between capecitabine maintenance and observation after 1st line XELOX chemotherapy. @*Materials and Methods@#Sixty-three patients treated with six cycles of XELOX for advanced GC in six hospitals of the Catholic University of Korea were randomized 1:1 to receive capecitabine maintenance or observation. The primary endpoint was progression-free survival (PFS), analyzed using a two-sided log-rank test stratified at a 5% significance level. @*Results@#Between 2015 and 2020, 32 and 31 patients were randomized into the maintenance and observation groups, respectively. After randomization, the median number of capecitabine maintenance cycles was 6. The PFS was significantly higher in the maintenance group than the observation group (6.3 vs. 4.1 months, P=0.010). Overall survival was not significantly different between the 2 groups (18.2 vs. 16.5 months, P=0.624). Toxicities, such as hand-foot syndrome, were reported in some maintenance group patients. Maintenance treatment was a significant factor associated with PFS in multivariate analysis (hazard ratio, 0.472; 95% confidence interval, 0.250–0.890; P=0.020). @*Conclusions@#After 6 cycles of XELOX chemotherapy, capecitabine maintenance significantly prolonged PFS compared with observation, and toxicity was manageable. Maintenance treatment was a significant prognostic factor associated with PFS.

6.
Cancer Research and Treatment ; : 1250-1260, 2023.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-999810

RESUMO

Purpose@#This study evaluated whether combination therapy is more effective than monotherapy in elderly patients with metastatic or recurrent gastric cancer (MRGC) as first-line chemotherapy. @*Materials and Methods@#Elderly (≥ 70 years) chemo-naïve patients with MRGC were allocated to receive either combination therapy (group A: 5-fluorouracil [5-FU]/oxaliplatin, capecitabine/oxaliplatin, capecitabine/cisplatin, or S-1/cisplatin) or monotherapy (group B: 5-FU, capecitabine, or S-1). In group A, starting doses were 80% of standard doses, and they could be escalated to 100% at the discretion of the investigator. Primary endpoint was to confirm superior overall survival (OS) of combination therapy vs. monotherapy. @*Results@#After 111 of the planned 238 patients were randomized, enrollment was terminated due to poor accrual. In the full-analysis population (group A [n=53] and group B [n=51]), median OS of combination therapy vs. monotherapy was 11.5 vs. 7.5 months (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.56 to 1.30; p=0.231). Median progression-free survival (PFS) was 5.6 vs. 3.7 months (HR, 0.53; 95% CI, 0.34 to 0.83; p=0.005). In subgroup analyses, patients aged 70-74 years tended to have superior OS with combination therapy (15.9 vs. 7.2 months, p=0.056). Treatment-related adverse events (TRAEs) occurred more frequently in group A vs. group B. However, among severe TRAEs (≥ grade 3), there were no TRAEs with a frequency difference of > 5%. @*Conclusion@#Combination therapy was associated with numerically improved OS, although statistically insignificant, and a significant PFS benefit compared with monotherapy. Although combination therapy showed more frequent TRAEs, there was no difference in the frequency of severe TRAEs.

7.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-977405

RESUMO

Background/Aims@#We compared the efficacy of the granisetron transdermal system (GTS) with that of ondansetron for controlling chemotherapy-induced nausea and vomiting (CINV) in patients treated with highly emetogenic chemotherapy (HEC). @*Methods@#We randomized a total of 389 patients to groups treated by GTS and ondansetron before HEC. The primary endpoint was the percentage of patients achieving complete response (CR; no retching/vomiting/rescue medication) of CINV from the time of chemotherapy initiation to 24 hours after the last administration of chemotherapy (prespecified non-inferiority margin of 15%). Quality of life (QoL) was also assessed using the Functional Living Index-Emesis (FLIE). @*Results@#The per protocol analysis included 152 (47.80%) and 166 patients (52.20%) in the GTS and ondansetron groups, respectively. In the full analysis set, the most common diagnosis, regimen, and period of chemotherapy were lung cancer (149 patients, 40.27%), cisplatin-based regimen (297 patients, 80.27%), and 1 day chemotherapy (221 patients, 59.73%). The CR rates were 86.84% and 90.36% in the GTS and ondansetron groups, respectively; the treatment difference was −3.52% (95% confidence interval, −10.52 to 3.48) and met the primary endpoint, indicating that GTS was not inferior to ondansetron. Patient satisfaction, assessed on the FLIE, showed significantly higher scores in the GTS group compared to the ondansetron group (mean ± standard deviation, 1,547.38 ± 306.00 and 1,494.07 ± 312.05 mm, respectively; p = 0.0449). @*Conclusions@#GTS provided effective, safe, and well-tolerated control of CINV and improved the QoL in HEC.

8.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-976896

RESUMO

Germinal matrix-intraventricular hemorrhage (GM-IVH) is among the devastating neurological complications with mortality and neurodevelopmental disability rates ranging from 14.7% to 44.7% in preterm infants. The medical techniques have improved throughout the years, as the morbidity-free survival rate of very-low-birth-weight infants has increased; however, the neonatal and long-term morbidity rates have not significantly improved. To this date, there is no strong evidence on pharmacological management on GM-IVH, due to the limitation of well-designed randomized controlled studies. However, recombinant human erythropoietin administration in preterm infants seems to be the only effective pharmacological management in limited situations. Hence, further high-quality collaborative research studies are warranted in the future to ensure better outcomes among preterm infants with GM-IVH.

9.
Angew Chem Int Ed Engl ; 61(44): e202209326, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36104313

RESUMO

Inverse-electron-demand Diels-Alder reaction (IEDDA) between fullerenes and 1,2,4,5-tetrazine generally requires harsh conditions and long reaction times due to their strong electron-accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C60 /C70 )-tetrazine reaction inside a porous Zn-porphyrinic cage (Zn-PB) under sustainable conditions by installing a tetrazine-based axle (LA) via metal-ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene-tetrazine adducts. Furthermore, the C60 -tetrazine adduct is rearranged upon hydration to a bent-shaped C60 -pyrazoline adduct that can be released from the Zn-PB cavity in the presence of excess LA, thus catalyzing the formation of C60 -pyrazoline adduct inside Zn-PB without product inhibition.

10.
Materials (Basel) ; 15(15)2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35955260

RESUMO

A magnesium potassium phosphate hydrate-based flame-retardant coating (MKPC) is formulated by dead-burnt magnesium oxide (magnesia) and potassium dihydrogen phosphate (KH2PO4), behaving as a matrix. Constituents of the MKPC include wollastonite, vermiculite, aluminum fluoride, aluminum trihydroxide, and calcium carbonate. Some of the ingredients inter-react to produce mullite whiskers at high temperatures, despite an acid-base hydration induced reaction between magnesia and KH2PO4. The MKPC's thermal, corrosion-resistant, mechanical, and flame-resistant properties were analyzed using scanning electron microscopy, electrochemical corrosion testing, compression testing, thermogravimetric analysis, and freeze/thaw tests. The results show that with the molar ratio = 4 of magnesia to KH2PO4, MKPC demonstrates lower thermal conductivity (0.19 W/m K), along with better corrosion resistance, stronger compressive strength (10.5 MPa), and higher bonding strength (6.62 kgf/cm2) to the steel substrate. Furthermore, acceptable additives to the formulation could enhance its flame-retardancy and increase its mechanical strength as well. Mullite whisker formed from the interaction of wollastonite, aluminum trihydroxide, and aluminum fluoride acts as an outer ceramic shield that enhances mechanical strength and compactness. In addition, Mg-containing minerals with calcium carbonate treated at high temperatures, transform into magnesium calcium carbonate after releasing CO2. At the optimum composition of MKPC (magnesia/KH2PO4 molar ratio = 4; wollastonite:vermiculite = 20:10 wt.%; aluminum trihydroxide = 10 wt.%; and calcium carbonate = 5 wt.%), coated on a steel substrate, the flame-resistance limit results exhibit below 200 °C on the back surface of the steel substrate after one hour of flaming (ca. 1000 °C) on the other surface, and the flame-resistance rating results demonstrate only 420 °C on the back surface of the steel substrate after three hours of flaming (>1000 °C) on the other surface. Both requirements for the flame-resistance limit and three-hour flame-resistance rating are met with the optimum compositions, indicating that MKPC plays an effective role in establishing flame-retardancy.

11.
Membranes (Basel) ; 12(7)2022 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-35877902

RESUMO

A novel cobalt-chelating polyimine (Co-PIM) containing an additional amine group is prepared from the condensation polymerization of diethylene triamine (DETA) and terephthalalehyde (PTAl) by the Schiff reaction. A Co, N-co-doped carbon material (Co-N-C), obtained from two-stage calcination in different gas atmospheres is used as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). The Co-N-C catalyst demonstrates a CoNx-type single-atom structure seen under high-resolution transmission electron microscopy (HRTEM). The Co-N-C catalysts are characterized by FTIR, XRD, and Raman spectroscopy as well. Their morphologies are also illustrated by SEM and TEM micrographs, respectively. Surface area and pore size distribution are found by BET analysis. Co-N-C catalysts exhibit a remarkable oxygen reduction reaction (ORR) at 0.8 V in the KOH(aq). From the LSV (linear-sweeping voltammetry) curves, the onset potential relative to RHE is 1.19-1.37 V, the half wave potential is 0.73-0.78 V, the Tafel slopes are 76.9-93.6 mV dec-1, and the average number of exchange electrons is 3.81. The limiting reduction current of CoNC-1000A-900 is almost the same as that of commercial 20 wt% Pt-deposited carbon particles (Pt/C), and the max power density (Pmax) of the single cell using CoNC-1000A-900 as the cathode catalyst reaches 361 mW cm-2, which is higher than Pt/C (284 mW cm-2).

12.
Polymers (Basel) ; 14(9)2022 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-35566952

RESUMO

Polyazomethine (PAM) prepared from the polycondensation between p-phenylene diamine (PDA) and p-terephthalaldehyde (PTAl) via Schiff reaction can physically crosslink (complex) with Co ions. Co-complexed PAM (Co-PAM) in the form of gel is calcined to become a Co, N-co-doped carbonaceous matrix (Co-N-C), acting as cathode catalyst of an anion exchange membrane fuel cell (AEMFC). The obtained Co-N-C catalyst demonstrates a single-atom structure with active Co centers seen under the high-resolution transmission electron microscopy (HRTEM). The Co-N-C catalysts are also characterized by XRD, SEM, TEM, XPS, BET, and Raman spectroscopy. The Co-N-C catalysts demonstrate oxygen reduction reaction (ORR) activity in the KOH(aq) by expressing an onset potential of 1.19-1.37 V vs. RHE, a half wave potential of 0.70-0.92 V, a Tafel slope of 61-89 mV/dec., and number of exchange electrons of 2.48-3.79. Significant ORR peaks appear in the current-voltage (CV) polarization curves for the Co-N-C catalysts that experience two-stage calcination higher than 900 °C, followed by double acid leaching (CoNC-1000A-900A). The reduction current of CoNC-1000A-900A is comparable to that of commercial Pt-implanted carbon (Pt/C), and the max power density of the single cell using CoNC-1000A-900A as cathode catalyst reaches 275 mW cm-2.

13.
Membranes (Basel) ; 12(1)2022 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-35054600

RESUMO

Cobalt-doped carbon nitride frameworks (CoNC) were prepared from the calcination of Co-chelated aromatic polyimines (APIM) synthesized from stepwise polymerization of p-phenylene diamine (PDA) and o-phthalaldehyde (OPAl) via Schiff base reactions in the presence of cobalt (II) chloride. The Co-chelated APIM (Co-APIM) precursor converted to CoNC after calcination in two-step heating with the second step performed at 100 °C lower than the first one. The CoNCs demonstrated that its Co, N-co-doped carbonaceous framework contained both graphene and carbon nanotube, as characterized by X-ray diffraction pattern, Raman spectra, and TEM micropictures. CoNCs also revealed a significant ORR peak in the current-voltage polarization cycle and a higher O2 reduction current than that of commercial Pt/C in a linear scanning voltage test in O2-saturated KOH(aq). The calculated e-transferred number even reaches 3.94 in KOH(aq) for the CoNC1000A900 cathode catalyst, which has the highest BET surface area of 393.94 m2 g-1. Single cells of anion exchange membrane fuel cells (AEMFCs) are fabricated using different CoNCs as the cathode catalysts, and CoNC1000A900 demonstrates a peak power density of 374.3 compared to the 334.7 mW cm-2 obtained from the single cell using Pt/C as the cathode catalyst.

14.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-918873

RESUMO

In vitro studies are essential to predict the clinical performance of ceramic widely used as restorative materials. Traditional experiments such as fracture toughness and flexural strength have been used to evaluate the properties of brittle ceramics. However, these experiments have a limitation that the load conditions, failure patterns, and load values at which failure occurs are not similar to human occlusal force ranges or clinical failures. On the other hand, the edge chipping test (ECT), which was recently introduced to study chipping fracture of ceramics, has similar failure patterns to clinical trials. In addition, the failure loads from ECT were similar to human occlusal force. ECT can be usefully used in the study of ceramic properties. In this literature review, a more clinically meaningful experimental study of ceramics by examining the meaning and limitations of traditional ceramic failure tests and comparing them with ECT.

15.
Materials (Basel) ; 14(21)2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34772152

RESUMO

Flame-retardant coatings have drawn much attention in recent years. In this study, an inorganic sodium silicate-based intumescent flame-resistance coating with an excellent flameproof properties is developed by mainly utilizing sodium silicate as the ceramizable binder, via hydrolysis and self-condensation reaction. Fly ash, metakaoline, and wollastonite behave as supplement cementing materials. Major formulation encompasses the combination of the ammonium polyphosphate and pentaerythritol as the flame-retardant additives, and aluminum hydroxide or expandable graphite as the intumescence-improving filler agents. Expandable graphite was found to play an important role in the eventual performance of flame-resistance testing. The results showed that solid interaction forces can be formed between metakaoline and sodium silicate, resulting in a similar material to geopolymer with excellent physical properties. After high-temperature flame testing, a densely complex protective layer of carbon-char created on top of the robust silicon dioxide networks offers notable flame resistance. An optimal ratio in this inorganic intumescent coating contains sodium silicate-metakaoline (weight ratio = 9:1)-ammonium polyphosphate and pentaerythritol, aluminum hydroxide (3, 3, 10 wt.%)-expandable graphite (1 wt.%), which can create 4.7 times higher expansion ratio compared with neat sodium silicate matrix. The results of flame testing demonstrate only 387.1 °C and 506.3 °C on the back surface of steel substrate after one and three hours flaming (>1000 °C) on the other surface, respectively, which could meet the requirements according to the level of fire rating.

16.
Polymers (Basel) ; 13(21)2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34771406

RESUMO

Aromatic polyimine (PIM) was prepared through condensation polymerization between p-phenylene diamine and terephthalaldehyde via Schiff reactions. PIM can be physically crosslinked with ferrous ions into gel. The gel-composites, calcined at two consecutive stages, with temperatures ranging from 600 to 1000 °C, became Fe- and N-doped carbonaceous organic frameworks (FeNC), which demonstrated both graphene- and carbon nanotube-like morphologies and behaved as an electron-conducting medium. After the two-stage calcination, one at 1000 °C in N2 and the other at 900 °C in a mixture of N2 and NH3, an FeNC composite (FeNC-1000A900) was obtained, which demonstrated a significant O2 reduction peak in its current-voltage curve in the O2 atmosphere, and thus, qualified as a catalyst for the oxygen reduction reaction. It also produced a higher reduction current than that of commercial Pt/C in a linear scanning voltage test, and the calculated e-transferred number reached 3.85. The max. power density reached 400 mW·cm-2 for the single cell using FeNC-1000A900 as the cathode catalyst, which was superior to other FeNC catalysts that were calcined at lower temperatures. The FeNC demonstrated only 10% loss of the reduction current at 1600 rpm after 1000 redox cycles, as compared to be 25% loss for the commercial Pt/C catalyst in the durability test.

17.
Polymers (Basel) ; 13(19)2021 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-34641057

RESUMO

The hydrophilic initiator potassium persulfate (KPS) was converted into a hydrophobic molecule by complexing with cetyltrimethylammonium bromide (CTAB) at both ends of the molecule (CTAPSu). Inverse emulsion polymerization thus proceeded inside micelles dispersed in the affluent toluene with CTAPSu as the initiator. Polyaniline (PANI) formed inside the micelles and entangled with Fe3O4 nanoparticles already esterified with oleic acid (OA). Iron composites consisted of OA-esterified Fe3O4 nanoparticles covered with PANI after de-emulsification. After calcination at 950 °C in an argon atmosphere, the resultant iron compound was a mixture of α-Fe (ferrite) and Fe3C (cementite), as determined by X-ray diffraction. Eventually, the calcined iron compounds (mixtures) demonstrated superparamagnetic properties with a high saturation magnetization (Ms) of 197 emu/g, which decayed to 160 emu/g after exposure to the atmosphere for four months.

18.
Polymers (Basel) ; 13(17)2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34502904

RESUMO

A quaternized polybenzimidazole (PBI) membrane was synthesized by grafting a dimethylimidazolium end-capped side chain onto PBI. The organic-inorganic hybrid membrane of the quaternized PBI was prepared via a silane-induced crosslinking process with triethoxysilylpropyl dimethylimidazolium chloride. The chemical structure and membrane morphology were characterized using NMR, FTIR, TGA, SEM, EDX, AFM, SAXS, and XPS techniques. Compared with the pristine membrane of dimethylimidazolium-functionalized PBI, its hybrid membrane exhibited a lower swelling ratio, higher mechanical strength, and better oxidative stability. However, the morphology of hydrophilic/hydrophobic phase separation, which facilitates the ion transport along hydrophilic channels, only successfully developed in the pristine membrane. As a result, the hydroxide conductivity of the pristine membrane (5.02 × 10-2 S cm-1 at 80 °C) was measured higher than that of the hybrid membrane (2.22 × 10-2 S cm-1 at 80 °C). The hydroxide conductivity and tensile results suggested that both membranes had good alkaline stability in 2M KOH solution at 80 °C. Furthermore, the maximum power densities of the pristine and hybrid membranes of dimethylimidazolium-functionalized PBI reached 241 mW cm-2 and 152 mW cm-2 at 60 °C, respectively. The fuel cell performance result demonstrates that these two membranes are promising as AEMs for fuel cell applications.

19.
Polymers (Basel) ; 13(14)2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34301136

RESUMO

Oleic acid (OA)-modified Fe3O4 nanoparticles were successfully covered with polyanilines (PANIs) via inverse suspension polymerization in accordance with SEM and TEM micrographs. The obtained nanoparticles were able to develop into a ferrite (α-Fe) and α″-Fe16N2 mixture with a superparamagnetic property and high saturated magnetization (SM) of 245 emu g-1 at 950 °C calcination under the protection of carbonization materials (calcined PANI) and other iron-compounds (α″-Fe16N2). The SM of the calcined iron-composites slightly decreases to 232 emu g-1 after staying in the open air for 3 months. The calcined mixture composite can be ground into homogeneous powders without the segregation of the iron and carbon phases in the mortar without significantly losing magnetic activities.

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