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The study involved the preparation of mixtures of phytic acid ionic liquid and water, which were analyzed for their rheological, frictional, and electrochemical properties. The viscosity and friction characteristics of the mixtures are significantly affected by the water content. Mixtures with low water content (below 30%) result in low friction and negligible wear because of the generation of a close adsorption film and high viscosity. Especially, steel tribo-pairs lubricated with mixtures containing 25% water exhibited friction coefficients lower than 0.06. However, when the water content exceeds 35%, the friction coefficient increases dramatically, and the tribo-surface suffers from severe corrosive wear due to the predominance of the tribo-film in the frictional properties. These results were confirmed through XPS and electrochemical testing.

Percutaneous endoscopic interlaminar discectomy (PEID) is widely used as a minimally invasive procedure that shows satisfying outcomes for the treatment of L5/S1 and even L4/5 disc herniation. PEID can be divided into direct and indirect approaches according to the established method of the working channel. The direct approach mainly utilizes the puncture needle directly through the intervertebral space into the intervertebral disc under non-direct vision and insertion of the guidewire into the puncture needle to guide the dilator and working channel to retract the ligamentum flavum, dural sac and nerve roots. This approach requires a skilled puncture technique, as damage to the nerve roots and dural sac can easily occur. Therefore, we improved this interlaminar access procedure; we placed the puncture target at the inferior endplate and performed preoperative epidurography to expose the spinal nerve roots and dural sac after the puncture needle was passed through the ligamentum flavum. Then, we positioned the puncture needle at the posterior edge of the superior centrum. Finally, we inserted the working sleeve for the operation. This approach is convenient and effectively reduces the learning curve and intraoperative complications. The aim of this study was to introduce the procedure and investigate the safety and efficacy of full-endoscopic interlaminar discectomy via an inferior endplate approach for the treatment of lumbar disc herniation.We performed full-endoscopic interlaminar discectomy via the inferior endplate approach in 321 patients who satisfied our inclusion criteria during the period from May 2014 to May 2017. All operations were completed under local anaesthesia. Under fluoroscopic guidance, we performed epidurography to expose the spinal nerve roots and dural sac. The working sleeve and endoscope were then introduced into the inferior endplate of the superior centrum. Herniated disc material was removed using forceps and a laser under clear endoscopic visualization. We retrospectively evaluated the 321 patients with more than 30 (range 12-48) months of follow-up. The therapeutic effects were assessed using scores of the visual analogue scale (VAS), Oswestry disability index (ODI), Macnab standard and infrared thermal imaging.The mean VAS score for radicular pain improved from 6.3 ± 1.01 preoperatively to 1.01 ± 0.35 at the final follow-up (P0.01). The mean ODI score improved from 85.5 ± 12 preoperatively to 12.4 ± 3.7 at the final follow-up (P0.01). According to the Macnab standard, the excellent and good outcome scores were 96.5%. The infrared thermal imaging scores indicated that the skin temperature of both lower extremities significantly improved 1 week after surgery compared with the preoperation temperature (P0.01).The inferior endplate approach for percutaneous endoscopic interlaminar discectomy provides a safe and very effective alternative for the treatment of lumbar disc herniation.

A kind of ecofriendly ricinoleic acid based ionic liquid was used as a multifunctional lubricant additive in glycerol solution. Its surface tension, anticorrosion and lubricating properties were investigated. Above the critical micelle concentration (CMC) it remarkably improves the anticorrosion and lubricating abilities of glycerol solution and its optimal concentration is 6%. Moreover, the increasing load from 25 N to 50 N improves the lubricity while high temperature and heavy load conditions are negative for the lubricity. The worn surfaces were analyzed using SEM-EDAX and Raman spectroscope. Meanwhile molecular dynamics (MD) simulations were performed to explore the absorption progress of the additive on iron surface. The lubrication mechanism is attributed to the formation of adsorbed layers and tribofilms.

In this study, polyhedral oligomeric silsesquioxane (POSS) based giant triblock molecules with precisely defined regio-configuration are modularly prepared through highly efficient coupling reactions. The length of the linker connecting neighboring nanoparticles is elaborately designed to regulate the geometric constraints. The triblock molecules adopt a folded packing during phase separation, and the regio-configuration imparts direct influence on the self-assembly behaviors. The ortho-isomers form periodic structures with a larger domain size, larger interfacial curvature, and enhanced phase stability. The regio-effect is closely related to the length and symmetry of the linker. As the linker extends, the neighboring particles gradually decouple, and the regio-effect diminishes. The symmetry of the linker shows an even more profound impact. This work quantitatively scrutinized the role of the linker, opening an avenue for engineering the assembled structures with molecular precision.

Polymeric chains made of "giant" monomers at a larger length scale provide intriguing insights into the fundamental principles of polymer science. In this study, we modularly prepared a library of discrete amphiphilic polymeric chains using molecular nanoparticles as repeat units, with exact control of composition, chain length, surface property, and regio-configuration. These giant polymeric chains self-assembled into a rich collection of highly ordered phases. The precise chemical structure and uniform chain length eliminate all the inherent molecular "defects", while the nanosized monomer amplifies minute structural differences, providing an ideal platform for a systematic scrutiny of the self-assembly behaviors at a larger length scale. The compositional and regio-configurational contribution was carefully studied. The regio-regularity is found to have a direct and profound impact on the chain conformation, leading to a distinct molecular packing scheme and therefore shifting the phase boundaries. With increasing the length of the linker, the regio-constraint gradually diminishes, and the neighboring particles would eventually be decoupled.

Background. As a traditional Chinese medicine tonic, Buzhong Yiqi decoction has the effects of invigorating Qi and lifting Yang. In this study, the effects of Buzhong Yiqi Shenge decoction combined with THP bladder perfusion on postoperative efficacy in bladder cancer were investigated. Methods. A total of 70 cases of bladder cancer patients were divided into the experimental group and control group according to the random number table method, with 35 cases in each group. The control group was treated with THP bladder perfusion. The experimental group was treated with Buzhong Yiqi Shenge decoction on the basis of the control group. The number of urine white blood cells, VEGF level, the incidence of adverse reactions, and KPS score were compared between the two groups before and after treatment. Results. After 3 and 6 months of therapy, the KPS score of the experimental group increased significantly compared with the control group. However, after 12 months of treatment, there was no difference in KPS scores between the two groups. Moreover, there was no significant variation in serum VEGF between two groups after 3 months of treatment. However, Buzhong Yiqi decoction notably reduced the level of VEGF after 6 months and 12 months. After 3 months, the urine white blood cell count was lower in the experimental group than in the control group. After 6 and 12 months, there was no difference in urine white blood cell count between the two groups. Furthermore, a total of 14 patients in two groups had reoccurrence after one year. Our results showed that there was no significant difference in postoperative recurrence rate between the experimental group and the control group. The occurrence rates of frequent and urgent urination, nausea/loss, and abnormal urine routine of appetite in the experimental group were significantly lower than those in the control group. But there was no difference in the occurrence rate of low heat, hematuria between the experimental group and the control group. Conclusion. Buzhong Yiqi decoction combined with THP bladder perfusion has no advantage in the short-term recurrence rate of bladder cancer patients. However, Buzhong Yiqi decoction can alleviate the symptoms of adverse reactions and improve the quality of life of patients.

Background. Previous studies have shown that Ampelopsin has an inhibitory effect on human tumors. However, the effect of Ampelopsin on renal cell carcinoma (RCC) is rarely reported. Therefore, this study aims to explain the role of Ampelopsin in RCC. Methods. Different concentrations of Ampelopsin (0, 10, 25, 50, and 100 μM) were used to treat 786-O cells. Cell viability was detected by MTT assay, colony formation assay, and flow cytometry assay. Transwell assay and Wound healing assay were used to detect cell migration and invasion. Western blot analysis was applied to detect protein expression. Results. Ampelopsin inhibited cell proliferation and induced apoptosis in RCC. And Ampelopsin can inhibit cell migration and invasion in RCC. All these results changed in a dose-dependent manner. Ampelopsin (100 uM) had the strongest inhibitory effect on cell viability and metastasis. In addition, Ampelopsin negatively regulated the PI3K/AKT signaling pathway in RCC cells. Moreover, Ampelopsin was only cytotoxic to RCC cells. Conclusion. Ampelopsin inhibits cell viability and metastasis in RCC by negatively regulating the PI3K/AKT signaling pathway.

The anti-shudder performance of automatic transmissions (AT) is highly dependent on automatic transmission fluids (ATFs). Additives of ATFs interact with the steel surfaces to form tribofilms to provide AT with the desired properties. Hence, establishing the relationship between the tribofilm and friction characteristics is the key issue for optimizing the anti-shudder performance. This paper evaluates the tribological response of the calcium phosphate tribofilm in a disk-on-disk friction test apparatus (Wazau), which is used to simulate the clutch friction process. The changes of the tribofilm during friction and the variations of the μ-v curves with the tribofilms were discussed. Results showed that the calcium phosphate tribofilm contributed to maintain the anti-shudder property.

This mini review summarizes recent progress on two-dimensional (2D) self-assembly of giant molecules. Two critical factors with significant impact on the formation of nanostructure are highlighted, i.e., the dimensional constraint of 2D geometry, and the conformational constraint imposed the rigid molecular nanoparticles (MNPs). Diverse 2D nanostructures have been fabricated in condensed state and solution by rational molecular design. The collective secondary interactions between functional groups on the periphery of the MNPs and their persistent shape, together with the dimensional limit, change the free energy landscape and lead to unconventional nanostructures. The unique molecular properties of giant molecules endow these 2D structures with promising technological applications.

Modern logistics has developed rapidly in China, and has become an important index to evaluate the level of urban development. This paper takes Jiangxi Province of China as the research object, chooses the relevant economic data of 11 main cities in 2018, then employs the entropy weighted TOPSIS method and cluster analysis method for the problem of ranking and classifying of urban logistics competitiveness. The research results can provide countermeasures and suggestions for the development of logistics industry in Jiangxi Province. The innovation of this paper is to propose a new method to evaluate the competitiveness of urban logistics based on overcoming the shortcomings of previous methods. The feasibility and validity of the method are verified by case analysis.

The higee technology was developed for synthesizing hydrophobic chain-modified CeO2 nanoparticles in hydrocarbon solvents. Salicylaldimine associated with CeCl3 was exploited to generate the nanoparticles with the help of NaOH and H2O2. The surface-modified CeO2 nanoparticles were stably and homogeneously dispersed in the organic solvent. The products were characterized by Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetry (TGA) and Nanopraticle Size Analyser. The results showed that the modified-CeO2 particles prepared were uniform nanosized and fluorite structured. The particle size distribution can be controlled by changing the rotation speed of the higee reactor.

Automatic transmission fluids (ATF) were tested using a new type disc-on-disc simulation tribo-test-rig Wazau triometer with the aim of studying the tribofilm formation on the steel surfaces during the engagement of wet friction clutches. XPS, SIMS, SEM and EDX were used to investigate the chemical composition of this tribofilm. The result confirms that there exist tribochemical reactions between ATF additives and steel rubbing surfaces. P/Ca/O element ratio of the tribofilm is consistent, which has never been reported before in the tribological field of clutch discs. All the results suggest that the chemical composition of this tribofilm is calcium phosphate. Since calcium phosphate ceramics have excellent mechanical and tribological properties, the friction characteristics of wet clutches must have been changed.

Sludge is an inevitable by-product of turbine oil during the operation of lubricating turbines. However, there are few reports of the detailed analytical results of the sludge. In addition, no global specification exists to evaluate the sludge formation from turbine oils. Hence, it is critical to analyze the contents of the sludge. In this study, we investigate both fresh and in-service (contains sludge) turbine oil based on ASTM standards. In-service turbine oil was first washed by petroleum ether to obtain the sludge and then characterized by FTIR, SEM, TG and EDAX. We found that the main compositions of sludge were C, O and N, while metals were

Treatment of tibial plateau fractures associated with anterior cruciate ligament (ACL) injuries can be challenging. Maintaining the joint surface and axis are two main principles for the management of patients with tibial plateau fractures. Herein, we describe a patient with tibial plateau fracture of Schatzker type VI associated with complete ACL rupture. Although in a two-stage reconstruction surgery for treatment of its rupture seem to be accepted by most orthopaedic surgeons in cases of ACL injuries, we treated our patient with ORIF in a one-stage ACL reconstruction surgery. At the 1-year follow-up, the patient gained full range of motion and was functioning well. We reviewed the literature on performing ORIF in a one-stage ACL reconstruction for the treatment of tibial plateau fractures, which seemed to be a reasonable management approach that supported its use for the treatment of this patient.

Objective We used a rabbit model of hepatic ischemia reperfusion in situ to observe the change of portal venous endotoxin level before reperfusion, and the effect of portal blood stasis removal on intestinal endotoxemia and hepatic ischemia reperfusion injury. The purpose was to find an ideal method for portal blood stasis removal and provide the experimental proof for clinical application of hepatectomy. Methods and Materials To investigate the effect of portal blood stasis removal on intestinal endotoxemia and hepatic ischemia reperfusion injury, a rabbit hepatic ischemia reperfusion injury model was established and treated with removal of portal blood stasis before the portal blood circulation was resumed. Serum endotoxin content, alanine aminotransferase (ALT), hyaluronic acid (HA), and content of malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD) and activation of nuclear factor-κB (NF-κB) in liver tissue were examined respectively. Results In portal blood stasis the level of serum endotoxin significantly decreased with each 2.5 mL blood removal ( P P > .05). Removing portal blood stasis ameliorated endotoxemia and hepatic ischemia reperfusion injury as shown by ALT, HA, MDA, SOD, TNF-α, IL-6, and activation of NF-κB compared to no removal. The first 5 mL portal blood stasis contains high volume of endotoxin which may be responsible for hepatic reperfusion injury. Conclusion Removal of portal blood stasis before the resume of splanchnic circulation may ameliorate intestinal endotoxemia and hepatic ischemia reperfusion injury.

To make biomass more accessible for enzymatic hydrolysis, lime pretreatment of Miscanthus giganteus with oxidants was explored from 100 to 150 °C. Composition data for the recovered solid were obtained to determine the effects of the reaction time, lime dosage, oxidant loading, and temperature on sugar production efficiency. Under selected conditions (0.2 g of lime/g of biomass, 200 psig O2, and 150 °C for 1 h), delignification was 64.7%. The pretreated biomass was then followed by enzymatic hydrolysis. The yield of cellulose in the recovered solid to glucose was 91.7% and hemicellulose to xylose was 67.3%, 7.1 and 18.2 times larger than those obtained from raw biomass, respectively. Pretreatment with oxidants substantially raised delignification of raw M. giganteus, thereby enhancing enzymatic hydrolysis to sugars, while results were not improved when pretreatment included ammonium molybdate.

Background Percutaneous endoscopic laminar discectomy is a typical minimally invasive discectomy operation that is classified into the percutaneous endoscopic transforaminal discectomy and the percutaneous endoscopic interlaminar discectomy. Based on whether the surgeon chooses to deal with the ligamentum flavum under endoscope guidance, percutaneous endoscopic discectomy by the interlaminar approach can be performed with a full endoscope technique with the intermittent endoscope technique. To our knowledge, there is no study comparing these two techniques in regard to their surgical effects and advantages. Therefore, we conducted this study to compare the cost, safety, and efficacy between the intermittent endoscopy technique and full endoscopy technique of endoscopic interlaminar lumbar discectomy at the L5–S1 level. Methods From September 2014 to March 2015, a total of 126 patients with radiculopathy due to L5–S1 disc herniation who were treated by a full endoscopy technique (65 patients) or intermittent endoscopy technique (61 patients) were included. Relevant data, such as duration time of the operation, hospitalization expenses, postoperative bed rest time, length of hospitalization, and complication rates, were recorded. Clinical outcomes were assessed by the visual analog scale score, modified MacNab criteria, and Oswestry disability index. Results In the full endoscope (FE) group, the mean duration time of surgery was 75.0 ± 11.9 min. The postoperative bed rest time was 6.5 ± 1.1 h, length of hospitalization was 3.8 ± 1.1 days, and complication rate was 7.69%. In the intermittent endoscopy (IE) group, the mean duration time of surgery was 43.0 ± 16.4 min. The postoperative bed rest time was 5.0 ± 1.1 h, length of hospitalization was 3.6 ± 1.2 days, and complication rate was 6.60%. The average hospitalization expenses of the FE group and IE group, respectively, were 32,069 ± 1086 RMB and 22,665 ± 899 RMB. There were significant differences in the surgical duration and hospitalization expenses (P 0.05). The postoperative Oswestry disability index and VAS were clearly improved in both groups compared with those of preoperation (P 0.05). Conclusions Both the full endoscopy technique and intermittent endoscopy technique achieved good outcomes, whereas the intermittent endoscopy technique is a more effective option for a shorter duration surgery and lower hospitalization expenses.

Two protic ionic liquids (PILs) were prepared and investigated on the tribological behavior of their different combinations in the glycerol-water mixture. Synergy between both PILs can remarkably enhance its antiwear property. Further, the tribological behavior of the optimal combination was explored considering different factors including concentration, temperature and load. All the concentrations demonstrate promising antiwear properties, though a 0.5% dose moderately outperforms other doses. The increase of temperature and load is favorable for the lubricating ability. Based on worn surface analyses and molecular dynamic simulations, the synergistic mechanism between both PILs as lubricant additives is ascribed to the coexistence of the mixed adsorption layers and the tribofilms containing sp2 bonded carbon, FeS and orthophosphate.

In this paper, we developed a new fluorescence method for highly sensitive and selective detection of the alkaline phosphatase (ALP) activity with phenyl phosphate (PP) as the enzyme substrate and water-soluble conjugated polymer PPESO3 as a fluorescent probe. Phenyl phosphate could be hydrolyzed to phenol via the ALP-catalyzed reaction. In the presence of horse radish peroxidase (HRP) and H2O2, phenol was rapidly oxidized to quinone which could efficiently quench the fluorescence of the conjugated polymer PPESO3. The fluorescence intensity change of PPESO3 is proportional to the concentration of ALP. Thus, we established a fluorescence method for ALP activity detection based on a water-soluble fluorescent conjugated polymer–enzyme hybrid system. Under the optimized conditions, a linear correlation was established between the fluorescence intensity ratio I/I0 (I0 and I were the fluorescence intensity of the sensing system in the absence and presence of ALP, respectively) and the concentration of ALP in the range of 0–30 U L−1, and the detection limit for ALP was 0.5 U L−1. The present method was applied to the determination of ALP in spiked human serum samples with satisfactory results.

A novel type of cross-linked proton exchange membrane of lower methanol permeation and high proton conductivity is prepared, based on a newly synthesized sulfonated cross-linker: carboxyl terminated benzimidazole trimer bearing sulfonic acid groups (s-BI). Compared to membranes cross-linked with non-sulfonated cross-linker (BI), SPEEK/s-BI-n membranes show higher IEC values and proton conductivities. Meanwhile, oxidative stability and mechanical property of SPEEK/s-BI-n membranes are obviously improved. Among SPEEK/s-BI-n membranes, SPEEK/s-BI-2 exhibits high proton conductivity, low swelling ratio (0.122 S cm −1 and 15.2% at 60 °C, respectively) and low methanol permeability coefficient. These results imply that the cross-linked membranes prepared with the newly sulfonated cross-linker are promising for the direct methanol fuel cells (DMFCs) application.

A series of macromolecular cross-linked polybenzimidazole (PBI) membranes have been successfully prepared for the high temperature proton exchange membrane fuel cell (HT-PEMFC) applications. Bromomethylated poly (aryl ether ketone) (BrPAEK) is synthesized and used as a macromolecular cross-linker, the cross-linking reaction can be accomplished at 160 °C using an easy facial heating treatment. The resulting cross-linked membranes CBrPBI-X (X is the weight fraction of the cross-linker) display excellent mechanical strength. After phosphoric acid (PA) doping, the mechanical strength and proton conductivity of the PA/CBrPBI-X membranes are both enhanced comparing with the pristine PA/PBI. Considering the tradeoff of the mechanical strength and proton conductivity, 10 wt% BrPAEK is demonstrated to be an optimum content in the matrix. For instance, the proton conductivity of PA/CBrPBI-10 is 0.038 S cm−1 at 200 °C, which is higher than that of pristine PA/PBI with the proton conductivity of 0.029 S cm−1 at the same temperature. Other properties of the cross-linked membranes are also investigated in detail, including the oxidative stability, solubility and thermal stability. All the results indicate that the PA/CBrPBI-10 membrane has the potential application in HT-PEMFCs.

A novel side-chain poly(arylene ether ketone) functionalized with 1,4-butane-sultone (SQNPAEK-x, "x" refers to the number of the attaching sulfobutyl groups in one unit) were synthesized for proton exchange membrane fuel cell. SQNPAEK-x showed high proton conductivity up to 0.317 S cm(-1) at 80 degrees C and excellent dimensional stability due to the remaining hydroxyl groups. Morphological investigations revealed that SQNPAEK-x contained more uniform ionic clusters than the main-chain sulfonated poly(arylene ether ketone), which increased the proton conductivity. Other properties such as water uptake, mechanical properties were also investigated. It should be noted that SQNPAEK-x possesses the best overall performance with proton conductivity (0.204 S cm(-1) at 80 degrees C) higher that Nafion 117, while the swelling ratio was equivalent (13.2% at 80 degrees C). All the results indicate that the SQNPAEK-x membranes are promising candidates for proton exchange membrane fuel cells. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Author(s): Yu, G; Afzal, W; Yang, F; Padmanabhan, S; Liu, Z; Xie, H; Shafy, MA; Bell, AT; Prausnitz, JM | Abstract: BACKGROUND: Miscanthus×giganteus (M.×giganteus) is a potential source for bioethanol or other useful products. Pretreatment of lignocellulosic biomass is an essential step prior to enzymatic hydrolysis to sugars and fermentation to bioethanol. RESULTS: In this work, a one-step process uses aqueous ammonia with or without hydrogen peroxide; a proposed two-step process uses aqueous ammonia in the first step and hydrogen peroxide in the second step. In the two-step process, overall 89.5% lignin is removed. The pretreated biomass is followed by using cellulase and β-glucosidase to convert cellulose and hemicellulose from the recovered solid to fermentable sugars. The conversion of cellulose to glucose is 90.2% and to xylose is 73.4%. Characterization data are obtained for the recovered solid using scanning electron microscopy (SEM), attenuated total reflection-infrared spectroscopy (ATR-IR), and X-ray diffraction (XRD) for better understanding of the two-step process. CONCLUSION: Results from the two-step process using aqueous ammonia and hydrogen peroxide separately are much better than those from the one-step process for removing lignin and for enhancing conversion to sugars by enzymatic hydrolysis. © 2013 Society of Chemical Industry.

This work concerns the effect of aqueous ammonia pretreatment at four temperatures and at 10, 20 or 30 wt.% ammonia. After 1 h, more than 65% delignification is achieved at 150 or 180 °C for high and for low concentrations of ammonia. When the delignified miscanthus is enzymatically hydrolyzed for 96 h using cellulases and beta-glucosidase, conversion of the recovered solid to glucose is 53.4% and to xylose 70.0%. Additional glucose and xylose can be obtained from the ammonia-containing aqueous phase. Increased ammonia concentration leads to better conversion. Fourier-transform infrared and Two-dimensional 13C–1H Heteronuclear Single Quantum Coherence (HSQC) Nuclear Magnetic Resonance spectroscopy provide data for the composition of the pretreated miscanthus and for that of the liquid extract. These spectra indicate that pretreatment with ammonia leads to de-acetylation of the xylan-backbone. The β-O-4′ linked aryl ether remains the most abundant linkage in the pretreated miscanthus.

Silane-cross-linked polybenzimidazole (PBI) membranes with high proton conductivity and excellent mechanical properties were successfully prepared by using a silane monomer, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), as a cross-linker. Fourier transform infrared spectroscopy and solubility tests were used to characterize and confirm the cross-linked structure in the membranes. The silane-cross-linked membranes displayed excellent chemical stability and improved mechanical strength. Especially at high temperature (130 °C), where the tensile strength value was in the range of 68.6 to 99.3 MPa, while that of the pristine PBI was 61.7 MPa. Moreover, the proton conductivity was significantly enhanced because the silane-cross-linked structure in the membranes could absorb more phosphoric acid. Considering the tradeoff of mechanical properties and proton conductivity, 3% KH560 in weight was demonstrated to be the optimum content in the membranes, for instance, the SCPBI-3/7.95 PA (the cross-linker content was 3 wt% and the PA doping level was 7.95) had a proton conductivity of 0.081 S cm−1 and that of the SCPBI-3/9.07 PA was 0.114 S cm−1 at 200 °C, while that of pristine PBI was 0.015 S cm−1 at 200 °C.

A cross-linked network is obtained by an end-group cross-linkable PBI (E-PBI) and 4,4′-diglycidyl (3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP). The formation of the network is proved by FT-IR and gel fraction test. Then, high temperature proton exchange membranes are constructed by incorporating the cross-linked network into poly(2,2′-(1,3-phenylene)-5,5′-bibenzimidazole) (m-PBI). The influences of the end-group cross-linked network on the properties of membranes are studied, such as, phosphonate acid doping ability, thermal stability, mechanical property, oxidative stability and proton conductivity. The E-PBI/TMBP in the membranes contributes to the improvement of acid doping ability, proton conductivity, mechanical properties and oxidative stabilities. The blend membranes with 20–90 wt% E-PBI/TMBP show higher proton conductivity than pristine PBI at 120 °C–180 °C. These results indicate that the end-group cross-linked blend membranes are promising materials as high temperature proton exchange membranes.

A series of novel block sulfonated poly(arylene ether ketone)s containing side-chain groups were synthesized by condensation polymerization and grafting reactions. The structures of the oligomer and the polymers were investigated by 1H NMR after each step. The synthetic process was simple and efficient, and the phase separation of the block polymers between the hydrophobic and the hydrophilic components became more apparent. The thermal stability of the membranes was studied by TGA. The proton conductivity of the Block-15 membrane reached up to 0.246 S cm−1 at 80 °C, which was high enough for practical use. Furthermore, the block membranes showed very strong mechanical properties, water uptake, and resistance to methanol permeability. This study shows that a combination of side chain and block structures are a simple and effective approach to increase the nanophase separation and improve the performance of the proton exchange membranes in fuel cells.

A novel series of naphthalene-based poly(arylene ether ketone) copolymers containing methoxy groups and hexafluoroisopropylidene diphenyl moieties (6F-MNPAEKs) were successfully synthesized by aromatic nucleophilic polycondensation. Chain-type fluorinated and sulfonated naphthalene-based poly(arylene ether ketone) copolymers (6F-SNPAEKs) were subsequently synthesized by demethylation and sulfobutylation. The chemical structures of 6F-SNPAEKs were confirmed by 1 H NMR. The 6F-SNPAEKs in acid form showed excellent thermal stability at elevated temperatures. The 6F-SNPAEK membranes were easily obtained by solution casting and properties for fuel cells were investigated in detail. The water uptake, swelling ratio and proton conductivity increased with degree of sulfonation (DS) and temperature. 6F-SNPAEK-90 showed the highest conductivity of 0.181 S cm −1 at 80 °C. The methanol permeability of the membranes was in the range of 0.238–6.49 × 10 −7 cm 2 s −1 , compared to 1.55 × 10 −6 cm 2 s −1 for Nafion 117. The membranes also showed excellent mechanical properties: the elongation at break was greater than 15%. These results indicate that the 6F-SNPAEK membranes are a promising candidate for use in direct methanol fuel cell (DMFC) applications.

A new approach has been proposed to obtain high-temperature proton exchange membranes based on novel cross-linked porous polybenzimidazole (PBI). The cross-linked porous PBI membranes (CpPBI) were prepared by leaching out a low-molecular-weight compound dibutyl phthalate and mixing 4,4′-diglycidyl (3,3′,5,5′-tetramethylbiphenyl) epoxy resin as a cross-linker. The porous PBI membranes (pPBI) were also prepared for comparison. Compared with pPBI membranes, the mechanical properties and the chemical stability of CpPBI membranes were significantly improved. Both the uncross-linked and cross-linked membranes were doped with phosphoric acid, which may be used as proton exchange membranes for high temperature fuel cell. The doping level of all the pPBI membranes was higher than that of pristine PBI, thus leading to a higher proton conductivity. Especially the CpPBI-10 (with a cross-linker content of 10 wt.% and a porogen content of 50 wt.%) had a relative high proton conductivity of 0.046 S cm −1 at 200 °C, which is higher than some of the known porous PBI membranes measured under similar conditions. All the remarkable results of the epoxy-cross-linked porous PBI membranes indicated that the CpPBI membranes could be a suitable candidate for high temperature proton exchange membrane fuel cell (HT-PEMFC) applications.

A highly sulfonated poly (ether ether ketone) with pendant amino groups (Am-SPEEK) has been synthesized. The resulting copolymer showed good solubility in common organic solvents. Then the pendant amino groups of the Am-SPEEK were utilized to react with two kinds of cross-linker, epoxy resin and dibromide, to yield various cross-linked membranes. After cross-linking, the membranes could not dissolve in common solvents, just became swollen. In generally, all the cross-linked membranes showed improved mechanical properties and high dimensional stabilities, whereas the uncross-linked membranes highly swollen or even dissolved in water at high temperature. The proton conductivity of the membranes increased with an increase in temperature. At 80 °C, all the cross-linked membranes showed high proton conductivity, in the range of 0.111–0.140 S cm−1. Especially, the TMBP cross-linked membrane showed a proton conductivity of 0.140 S cm−1, which was higher than that of Nafion 117 (0.125 S cm−1). The membranes with high proton conductivity, good oxidative stability, and improved methanol residence have been successfully developed. Furthermore, the influence of different main chain of the cross-linker on the performance of the cross-linked membranes was also investigated.

Novel self-crosslinked alkaline electrolyte membranes with high hydroxide ion conductivity, excellent dimensional stability and extraordinary solvent resistance stability are synthesized successfully without using any catalyst or separate crosslinker. Monitored by 1 H NMR analysis, the synthetic process of trimethyl poly (ether sulfone)-methylene quaternary ammonium hydroxide (TPQAOH) is found to be simple and efficient. The chemical and thermal stability of the synthetic SCL-TPQAOH-x membranes are better than other anion exchange membranes. At the same time, the hydroxide ion conductivity of SCL-TPQAOH-0.67 membrane reaches 33 mS cm −1 with an IEC value of 1.07 mmol g −1 at 80 °C, which complies with the requirements of alkaline fuel cells. This investigation also proves that self-crosslinking technology is a very simple and effective approach in improving the performance of alkaline electrolyte membranes.

The epoxy resin with a trifluoromethyl side chain, (3-trifluoromethyl) phenylhydroquinone epoxy resin (3F-PQE), was synthesized via a three-step procedure. The chemical structures were confirmed by FT-IR, 1 H NMR, 13 C NMR and elemental analysis. A series of trifluoromethyl epoxy networks has been prepared with four curing agents: poly (propylene glycol) bis (2-aminopropy) ether (D230), 2-methylimidazole (2MI), 4, 4-methylene-dianiline (DDM) and phthalicacidanhydride (PA). All samples exhibited excellent thermal stabilities (the decomposition temperature of 5% weight loss (Td)) ranged from 335 to 362 °C in N 2 and 291–355 °C in air). The 3F-PQE-DDM sample showed the highest T g of all the samples. Moisture absorption of 3F-PQE-DDM and 3F-PQE-PA at 80 °C for 24 h was no more than 1 wt %. The cured fluorinated epoxy resins exhibited that the contact angles were more than 90°, which is the hydrophobic properties.

In order to enhance the ion exchange capacity (IEC) in the proton exchange membrane materials, a novel sulfonated poly(arylene ether ketone) (SQNPAEK) containing tri-side chains in one unit is synthesized by direct polymerization. The SQNPAEK membrane shows excellent proton conductivity up to 0.102S cm(-1) at 80 degrees C, which are superior to previous side-chain-type and main-chain-type sulfonated polymer membranes at similar IEC. Cross-linked membranes are then obtained by a heating reaction at 190 degrees C, using 4,4'-diglycidyl (3,3',5,5'-tetramethylbiphenyl) epoxy resin (TMBP) as the cross-linker. As expected, the water uptake and the methanol permeability of the cross-linked membranes decrease with increasing the content of TMBP. Compared to Nation 117, the cross-linked membranes show comparable proton conductivities and much higher selectivities, which are in the range of 5.18 x 10(5)-1.46 x 10(6) S s(-1) cm(3). Other properties of the cross-linked membranes, such as mechanical properties, thermal properties, are also investigated. All the results indicated that the cross-linked membranes based on SQNPAEKs and TMBP are promising candidate for direct methanol fuel cells. (C) 2011 Elsevier B.V. All rights reserved.

A diamine-terminated polybenzimidazole oligomer (o-PBI) has been synthesized for introducing the benzimidazole groups (BI) into sulfonated poly(ether ether ketone) (SPEEK) membranes. SPEEK/o-PBI/4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP) composite membranes in situ polymerization has been prepared for the purpose of improving the performance of SPEEK with high ion-exchange capacities (IEC) for the usage in the direct methanol fuel cells (DMFCs). The composite membranes with three-dimensional network structure are obtained through a cross-linking reaction between PBI oligomer and TMBP and the acid–base interaction between sulfonic acid groups and benzimidazole groups. Resulting membranes show a significantly increasing of all of the properties, such as high proton conductivity (0.14 S cm−1 at 80 °C), low methanol permeability (2.38 × 10−8 cm2 s−1), low water uptake (25.66% at 80 °C) and swelling ratio (4.11% at 80 °C), strong thermal and oxidative stability, and mechanical properties. Higher selectivity has been found for the composite membranes in comparison with SPEEK. Therefore, the SPEEK/o-PBI/TMBP composite membranes show a good potential in DMFCs usages.

Tetramethylbisphenol F epoxy resin (TMBPFE) was successfully synthesized based on tetramethylbisphenol F (TMBPF) and epichlorohydrin with tetrabutylammonium bromide as the catalyst. The structure of TMBPFE was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance and elemental analysis. Then, a mixed system composed of TMBPFE and 4,4′-diglycidyl (3,3′,5,5′-tetramethylbiphenyl) epoxy (TMBP) was prepared by a melting method, i.e. without any solvent. Both the TMBPFE and the mixed system were cured using 4,4′-diaminodiphenyl methane (DDM) as the curing agent. The thermal properties of TMBPFE and the mixed system were studied using differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis (TGA). The results showed that the TMBP mixed in the TMBPFE matrix had little effect on the thermal properties of TMBPFE. However, the glass transition temperature improved markedly with increasing content of TMBP. Moreover, the TGA results showed that the degradation characteristics of TMBPFE resins did not seriously decrease when TMBP was incorporated into the TMBPFE matrix, although there are large steric hindrance biphenyl groups in TMBP. Both TMBPFE and the TMBPFE/TMBP system have potential applications in electrical and electronic fields. Copyright © 2011 Society of Chemical Industry

An approach has been proposed to prepare the reinforced phosphoric acid (PA) doped cross-linked polybenzimidazole membranes for high temperature proton exchange membrane fuel cells (HT-PEMFCs), using 1,3-bis(2,3-epoxypropoxy)-2,2-dimethylpropane (NGDE) as the cross-linker. FT-IR measurement and solubility test showed the successful completion of the crosslinking reaction. The resulting cross-linked membranes exhibited improved mechanical strength, making it possible to obtain higher phosphoric acid doping levels and therefore relatively high proton conductivity. Moreover, the oxidative stability of the cross-linked membranes was significantly enhanced. For instance, in Fenton’s reagent (3% H 2 O 2 solution, 4 ppm Fe 2+ , 70 °C), the cross-linked PBI-NGDE-20% membrane did not break into pieces and kept its shape for more than 480 h and its remaining weight percent was approximately 65%. In addition, the thermal stability was sufficient enough within the operation temperature of PBI-based fuel cells. The cross-linked PBI-NGDE-X% (X is the weight percent of epoxy resin in the cross-linked membranes) membranes displayed relatively high proton conductivity under anhydrous conditions. For instance, PBI-NGDE-5% membrane with acid uptake of 193% exhibited a proton conductivity of 0.017 S cm −1 at 200 °C. All the results indicated that it may be a suitable candidate for applications in HT-PEMFCs.