Degree Of Grafting Research Articles

Architecting side chain grafted poly (vinylidene fluoride) based graphene oxide composite polyelectrolyte membranes for hydrogen and direct methanol fuel cells

Chemically modified poly (vinylidene fluoride) (PVDF) as polyelectrolyte has generated immense interest due to its high efficiency in electrochemical energy devices. Herein, the design of a polymer electrolyte membrane (PEM) is formulated by the synergistic fusion of graphene oxide (GO) into chemically grafted PVDF with 2-acrylamido-2-methylpropane sulfonic acid (AMPS) by solution phase intercalation producing GO@PVDF-g-PAMPS composite membranes. Ozone-induced graft copolymerization technique is employed to prepare PVDF-g-PAMPS with 18.3% (w/w) degree of grafting. Incorporation of GO into the polymeric membrane generates appropriate hydrophilic-hydrophobic phase separation and constructs well-organized sub-nano slit-like pathways that elevate the proton conduction. PAG-0 membrane without any filler shows a proton conductivity (κ) of 15.1 mS/cm at 80°C whereas PAG-2 membrane (with 2% w/w GO loading) shows a κ of 25.9 mS/cm under similar conditions. The presence of a perfluorinated backbone furnishes excellent oxidative stability to the PEMs by retaining 95% of total mass and 97.3% of κ after dipping in harsh Fenton's reagent at 60°C for 6 h. Representative PAG-2 shows a peak power density of 152.9 mW/cm2 with a maximum current density of 480.6 mA/cm2 (fuel cell operating conditions: 75°C at 100% RH) in hydrogen fuel cell and a peak power density of 37.7 mW/cm2 in methanol fuel cell. Moreover, PAG-2 retains 91% of its initial OCV after 50 h of the durability test.

Maillard reacted wheat gluten and polydextrose complex enhances the emulsifying properties and stability of Pickering emulsion

This study aims to explore the characteristics and stability of Pickering emulsion based on the Maillard reaction products of polydextrose (PDX) and gluten. The effects of the PDX:gluten ratio (from 0.0:1 P0.0G1 to 2.4:1 P2.4G1) during Maillard reaction on Pickering emulsion quality were examined. The degree of PDX grafting to gluten increased from 0.51%±0.05% to 18.99%±0.98% when the PDX:gluten ratio increased from 0.2:1 to 2.2:1. Scanning electron microscopy and infrared spectroscopy confirmed the structural change and covalent interaction of PDX–gluten conjugate. The P2.2G1 conjugate showed a higher emulsification activity (1.82±0.04 m2/g) compared with P0.0G1 (0.97±0.05 m2/g). The particle size, ζ-potential value and confocal laser scanning microscopic image of PDX–gluten conjugate-based emulsion were compared with those of gluten-based emulsion to illustrate the stability role of PDX–gluten conjugate in the interfacial layer of Pickering emulsion. This study demonstrated that the Maillard reacted gluten–PDX conjugate was a potential stabilizer for Pickering emulsions. These findings provided a foundation knowledge for the construction of Pickering emulsion based on PDX–gluten conjugates.

Effect of ultrasound-assisted Maillard reaction on functional properties and flavor characteristics of Oyster protein enzymatic hydrolysates

To address the delamination phenomenon during storage and flavor characteristics of Oyster protein hydrolysates (OPH). In this study, xylo-oligosaccharides (XOS) were selected to covalently graft with OPH through ultrasound-assisted Maillard reaction, and the effect of ultrasound-assisted Maillard reaction on the structure, functional properties, and flavor characteristics of OPH were investigated. The results revealed that the ultrasound treatment led to a 1.46-fold increase in the degree of grafting compared with the conventional wet-heat Maillard reaction methods. Structural analyses at various levels indicated substantial alterations in the OPH structure following the ultrasound-assisted Maillard reaction. More ordered α-helical secondary structures were shifting to random coiling, the tertiary structure showed more stretching changes, and the surface structure was characterized by loose and porous features. Compared with OPH, the solubility of the ultrasound-assisted Maillard reaction products (OPH-U-M) increased from 54.67% to 70.14%, leading to a notable enhancement in storage stability. Flavor profile analysis demonstrated a decrease in unsaturated aldehydes and ketones presenting fishy and bitter aromas, while an increase in presenting meat aroma compounds was observed in OPH-U-M. Furthermore, OPH-U-M exhibited superior antioxidant properties with DPPH and ABTS radical scavenging abilities enhancing 46.05% and 42.09% in comparison with OPH, respectively. The results demonstrated that covalently binding with XOS under ultrasonication pretreatment endowed OPH with superior functional properties (including solubility, storage stability, and antioxidant activity), and the improvement of flavor profile. This study can provide theoretical guidance and practical implications for promoting the processing applications of oyster protein.

Cyclic Continuous Glycation Enhanced Dispersibility of Myofibrillar Protein: Reaction Efficiency and Sites Modification.

Reaction efficiency in glycation lacks sufficient attention, leading to the waste of process costs. Cyclic continuous glycation (CCG) is an effective approach to accelerate covalent binding between myofibrillar protein (MP) and glucose. This study elucidated that CCG promoted the exposure of reactive glycated sites in MP with full unfolding of secondary and tertiary structures. Notably, the glycation rate was significantly increased by 65.43%. Physicochemical properties indicated that MP-glucose conjugates with high graft degree exhibited favorable solubility, dispersibility, and thermal stability. Furthermore, proteomics was applied to reveal the glycated sites and products in glycoconjugates of MP. Glycation preferentially acted on the tails of the myosin heavy chain. The glucosylation modification on the head region was enhanced by CCG contributing to the inhibition of the head-head interaction. Overall, this study systematically clarifies the mechanism of CCG, providing a theoretical basis for the application of glycation in innovative meat products.

Модификация твердофазной полимерной поверхности путём прививки акриловых мономеров

Graft copolymerization onto a solid polymer surface is an effective tool for its modification. A large number of works have been published and require systematization. A search and review of English-language scientific literature devoted to the graft copolymerization of acrylic monomers onto a polymeric solid-phase surface have been carried out. Grafting onto plates and films, as well as fibers and colloidal particles, is considered. It has been revealed that the most popular substrates for graft copolymerization are, besides polyethylene, propylene and polyethylene terephthalate; polyurethanes, polyfluoroethylenes, rubbers, etc. Graft polymerization mainly proceeds on amorphous areas of the substrate and does not destroy the crystalline phase. It is possible to use the methods of controlled radical polymerization (ATRP, RAFT). Of the acrylic monomers, acrylic and methacrylic acids, glycidyl acrylate and glycidyl methacrylate, and others have been used, while the main method has been UV photopolymerization with an initiator–benzophenone. Of the three aliphatic ketones (acetone, methyl ethyl ketone and methyl propyl ketone), acetone has been the best solvent. Cophotoinitiators have been also used (a synergistic effect was observed), corona discharge, gamma radiation (60Co), ozone and plasma treatment, and a supercritical CO2 medium. The degree of grafting has been controlled by changing the soaking time in the monomer, pressure, concentration of monomer and initiator in the liquid phase, reaction temperature and reaction time. A new technology of graft polymerization with photopatterning has also been proposed. Problems of graft polymerization in terms of surface modification of polymer materials (hydrophilization of the surface, improving paintability and wettability, enhancing adhesion to certain surfaces, biocompatibility) are touched upon, and possible areas of their application are outlined.

Quantifying the Abundance of Alkane Moieties in Lignins with FTIR Spectroscopy and PLS Regression; Estimating Grafting Degree of Esterification

Quantifying the Abundance of Alkane Moieties in Lignins with FTIR Spectroscopy and PLS Regression; Estimating Grafting Degree of Esterification

Glycosylated gelatin prepared based on electron beam irradiation and its physicochemical properties

The influence of electron beam irradiation (EBI) treatment on the modification of gelatin-galactose glycosylation was thoroughly examined. The results of the degree of grafting and browning revealed that EBI triggered the glycosylation reaction of gelatin. The degree of glycosylation exhibited a gradual increase with the rising irradiation dose, reaching a maximum of 25 kGy. Moreover, the irradiation process opened up gelatin's internal structure, exposing its hydrophobic groups. This exposure led to an enhancement in sample surface hydrophobicity. The fluorescence intensity at the maximum emission wavelength of the fluorescence spectra decreased; Fourier infrared spectroscopy demonstrated a new absorption peak at 1074 cm−1 for the glycosylation product. These findings substantiate that gelatin formed a new product through covalent bonding with galactose. Glycosylation boosted the emulsification stability of gelatin from 1.92 min to 10.42 min and improved its emulsification and rheological properties. These outcomes affirm that EBI can effectively induce the glycosylation reaction of gelatin, thereby enhancing its functional properties. In addition, EBI has the potential to supplant the conventional heating glycosylation method. This study lays a solid theoretical foundation for the future application of glycosylation and gelatin.

Improving physicochemical and biological properties of gelatin‐xylooligosaccharide conjugates by Maillard reaction

SummaryMaillard reaction can enhance the functional characteristics of the protein. Herein, we investigated changes in the physicochemical and biological properties of gelatin (GA)‐xylooligosaccharide (XOS) conjugates following Maillard reaction. The results showed that the browning intensity of the conjugates increased with the prolongation of heating time. Additionally, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis revealed some macromolecule polymer formed, and the grafting degree of GA was augmented to 40.05% with prolongation of heating time. GA glycation with XOS decreased α‐Helix content and increased level of β‐Turn level, and exerted a slight impact on contact angle. Moreover, the results of in vitro simulated gastrointestinal digestion analysis showed that the GA‐XOS mixture enhanced resistance to digestion after Maillard reaction for 60 min, affording hydrolysis ratios ranging from 17.86–27.79% and 25.03–35.47% in simulated gastric fluid and intestinal fluid, respectively. The antioxidant ability and heat stability of the conjugates was visibly enhanced following heating treatment. Additionally, increasing the mass of XOS accelerated the antioxidant capacities of GA‐XOS conjugates. The finding will assist the fabrication of GA‐XOS conjugates with highly functional properties by Maillard reaction.

Mechanistic insights into the interaction of Lycium barbarum polysaccharide with whey protein isolate: Functional and structural characterization

Protein-polysaccharide interactions are crucial for food system structure and stability. This study investigates the interaction of Lycium barbarum polysaccharide (LBP) at 0–2.00 % concentrations with whey protein isolate (WPI), focusing on functionality and structural changes. LBP covalently grafted onto WPI, as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), forming WPI-LBP complexes with a maximum degree of grafting (DG) of 44.58 % at 2.00 % LBP. This grafting reduced WPI's surface hydrophobicity (H0) and improved solubility, emulsifying properties, and digestibility under certain conditions, with optimal antioxidant activity at 1.00 % LBP. Multispectral analysis and microscopy showed LBP grafting alters WPI's secondary, tertiary, crystalline, and micro/nanostructures. The comprehensive analysis indicates that the interaction between LBP and WPI involves covalent bonding, hydrogen bonding, hydrophobic interactions, and electrostatic forces, as supported by zeta potential and chemical forces results. These findings suggest LBP-protein complexes as promising food materials for enhancing functionality and stability in the food industry.

Peroxide free radical grafting of maleic anhydride onto polyethylene under high melt temperature: A comprehensive approach

“Flash Reactive Extrusion” under very high temperatures (T=200–420°C) allowed to graft maleic anhydride onto polyethylene (PE) without the use of conventional free radical initiators such as peroxides. Herein, the use of unusual temperatures induced the formation of radicals through degradation/chain scission of the PE backbone and the latter radicals were able to react with maleic anhydride (MA) and yielding a MA grafting degree close to 1.4 wt% at 390°C. Moreover, the MA grafting mechanistic scheme was deeply discussed with the help of 1H NMR and 13C NMR analysis and it was pointed out that β-scissions reactions are favoured in comparison with the cross-linking ones at very high temperatures for the thermal initiation step with a MA grafting mainly onto the PE side chain.

Maillard conjugates of whey protein and prebiotic dietary fibers: Emulsion properties, encapsulation efficiency and chemical stability after in vitro gastrointestinal digestion

The incorporation of dietary fibers into food formulations is a promising approach to developing new functional ingredients. In this study, we investigated the formation of Maillard conjugates using whey protein concentrate (WPC) combined with fructooligosaccharides (FOS) and xylooligosaccharides (XOS). These conjugates, innovatively utilized as emulsifiers for annatto seed oil, were subjected to in vitro gastrointestinal digestion to assess their chemical stability and effectiveness as encapsulating systems. Our study confirmed the occurrence of the Maillard reaction through different methods, including grafting degree (GD) assessment and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) to evaluate molecular weight variations in the proteins. The key innovation of our research lies in demonstrating the conjugation process through carbohydrate mass balance analysis using High-Performance Anion Exchange Chromatography coupled with Pulsed Amperometric Detection (HPAEC-PAD). The GD for the WPC-XOS and WPC-FOS was 46 ± 3 % and 56 ± 3 %, respectively. Our findings suggest that sugar quantification could serve as a novel approach to confirming the formation of Maillard conjugates. The emulsions stabilized by these conjugates exhibited larger oil droplet sizes compared to those stabilized by WPC alone yet maintained high encapsulation efficiency (≥ 90 %). Notably, the WPC-XOS emulsion demonstrated kinetic stability after 30 days of storage at 4°C, while the WPC-FOS emulsion showed signs of creaming after just 16 days. In vitro gastrointestinal digestion revealed that while the conjugates were susceptible to enzymatic degradation, the FOS and XOS sugars displayed gastrointestinal resistance of up to 82 % and 83 %, respectively. This study highlights the potential of WPC-XOS conjugates not only as effective emulsifiers but also as functional ingredients that enhance the nutritional and antioxidant properties of food products, presenting a novel approach to functional food development.

The effect of polysaccharide type on dielectric barrier discharge (DBD) plasma glycosylation of sodium caseinate-part I: Physicochemical, structural and thermal properties

This study aimed to investigate the impact of polysaccharide type on the physicochemical, structural, and thermal properties of dielectric barrier discharge (DBD) plasma glycosylated sodium caseinate (SC). The polysaccharides Quince seed gum (QSG), carboxymethyl cellulose (CMC), and maltodextrin (MD) were mixed with SC and treated with DBD plasma at 18 kV for 10 min. The grafting degree, electrophoresis pattern, FTIR, XRD, carbonyl, sulfhydryl, and di-tyrosine content, FE-SEM, color, and thermal properties of SC and its polysaccharide mixtures before and after plasma treatment were analyzed. Results showed that the SC-QSG conjugate had the highest glycation degree and color change after plasma treatment. The SC-CMC and SC-QSG conjugates exhibited disappearance of distinct SC bands in electrophoresis pattern compared to SC. Also, significant changes in functional group and crystallinity were occurred in SC-CMC conjugate. Plasma treatment caused oxidation of SC, but the presence of polysaccharides offered protection against oxidation. The microstructure of SC was altered by mixing with polysaccharides and exposure to plasma. Also, the mixtures indicated higher thermal stability after plasma treatment. Results confirmed that the generation of protein-polysaccharide conjugates through DBD plasma technique was depended on with SC-MD conjugate unable to form through this method.

Effect of electron beam irradiation on glycosylation reaction and structural characterization of whey isolate protein.

Whey protein isolate (WPI) is a high-quality animal protein resource. The modification of WPI through physical, chemical and biological methods can substantially improve the functional properties of proteins. This study investigated the effect of electron beam irradiation (EBI) on the modification of WPI-xylose glycosylation. The degree of grafting and browning revealed that EBI promoted WPI glycosylation. The maximum emission wavelength of intrinsic fluorescence was red-shifted and the fluorescence intensity was reduced, suggesting that irradiation induced the unfolding of the WPI structure, thereby promoting glycosylation. Fourier-transformed infrared spectroscopy revealed that the covalent binding of the conjugates occurred on the introduction of the hydrophilic groups, resulting in decreased surface hydrophobicity. When compared with conventional wet-heat glycosylation, irradiation-assisted glycosylation improved the emulsifying activity of WPIfrom 179.76 ± 0.83 to 277.83 ± 1.44 m2 g-1, and the emulsifying and rheological properties improved. These results confirmed that EBI can increase the degree of WPI glycosylation and improve the functional properties of proteins, thereby laying a theoretical foundation for the further application of WPI. © 2024 Society of Chemical Industry.

Enhancing silica scaling resistance of high-pressure reverse osmosis membranes through surface grafting with various sulfonic acid monomers

Silica scaling is a major challenge in the application of high-pressure reverse osmosis (RO) membranes. In this work, we modified commercially available RO membranes by grafting different sulfonic acid monomers onto their surface using redox polymerization. We systematically studied the effects of various sulfonic acid monomers on membrane performance. Due to the different grafting abilities of sulfonic acid monomers on the membrane, the modified membranes exhibited different physicochemical properties. Simulated silica scaling experiments revealed that the initial permeate flux and sulfonic acid grafting rate of the membrane played crucial roles in its antifouling performance. Molecular dynamics (MD) simulation indicated that the adsorption of silica scale on the membrane was positively correlated with the grafting degree of sulfonic acid monomers. The membrane modified with 3-sulfopropyl potassium methacrylate (SPM) demonstrated a 14 % higher initial flux than the pristine membrane and the highest sulfonic acid grafting rate, resulting in the lowest flux decay rate. Additionally, the SPM modified membrane outperformed the pristine membrane against composite foulants with organic matters and silica. Our research demonstrated that the redox grafting polymerization of sulfonic acid monomers can simultaneously improve the flux and silica scaling resistance of RO membranes without compromising salt rejection. This provides a scalable strategy for preparing RO membranes with enhanced resistance to silica scaling.

Performance Enhancement of Biopolyester Blends by Reactive Compatibilization with Maleic Anhydride-Grafted Poly(butylene succinate-co-adipate).

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging.

Ultrasound-assisted glycosylation of ovalbumin and dextran conjugate carrier for anthocyanins and their stability evaluation

Anthocyanins (AC) are vulnerable to degradation when affected by external factors. The present study employed ultrasound-assisted glycosylation of ovalbumin (OVA) and dextran (Dex) to generate conjugate carrier for AC to improve its stability. The results showed that sonication significantly improved the progression of Maillard reaction to OVA. Compared to traditional glycosylation, ultrasound treatment showed a higher degree of grafting, a lower number of free-SH, and smaller particle size and uniform distribution. The SDS-PAGE results indicated covalent interaction. Intrinsic fluorescence (INF), Fourier transform infrared spectroscopy (FTIR), and Circular dichroism (CD) analysis results suggested that ultrasound-assisted glycosylation altered the OVA structure. The scanning electron microscope (SEM) and X-ray diffractometer (XRD) observed that the ultrasound-assisted complex had a more compact and smoother structure and protein unfolding were better. The protein solubility increased significantly after glycosylation. Thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) indicated that the glycosylated conjugates can significantly improve the thermal stability of AC In addition, the AC showed an improved processing and storage stability when conjugated with glycosylated carrier. The glycosylated protein-anthocyanins complex may help provide new ideas and scientific basis for the development of naturally sourced anthocyanins-relevant products in pharmaceutical and food industry applications.

SEPS functionalized PEG copolymer for improved toughness without obvious plasticization in epoxy resin

AbstractThe effects of grafting level of polyethylene glycol (PEG) grafted styrene ethylene propylene styrene (SEPS) on the intrinsic brittleness of epoxy thermosets were studied. The SEPS‐g‐PEG block copolymer (BCP) was synthesized by grafting various grafting degree of PEG (i.e., 10%, 20%, 30%, and 40%) on polystyrene (PS) blocks of SEPS following Williamson ether synthesis method. A total of 10 wt% of the BCP modifiers were dispersed in epoxy thermosets. PEG side chains were miscible in the epoxy which formed a uniform BCP dispersion within the epoxy thermoset matrix. As the degree of PEG grafting was increased, the BCP phase was absorbed in the epoxy matrix. This absorption occurred because the increase in PEG grafting provided more miscible PEG chains to bind the BCP and epoxy nanostructures together. The differential scanning calorimeter and dynamic mechanical thermal analysis analyses indicated that BCP toughened epoxy exhibited an improved glass transition temperature (Tg). At a 40% PEG grafting degree in the BCP, the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) increased up to 80% and 180%, respectively. This trend suggested that the energy associated with fractures could be absorbed through the deformation of the softer phases when a load was applied to them.

Soluble hemp protein-xylose conjugates fabricated by high-pressure homogenization and pH-shifting treatments.

The process of Maillard conjugation occurs with plant proteins and sugars and can be influenced by several factors, such as processing time, pH, and shear force. By utilizing cavitation processes such as high-pressure homogenization (HPH) and pH-shifting, it is possible to regulate the degree of grafting, functional characteristics, and structural changes in the formation of conjugates. The present study aimed to improve the hemp protein concentrate (HPC) through two different conjugation techniques: HPH and pH-shifting-assisted processes. The best conjugation conditions for the conventional method were identified as a 1:2 HPC to xylose ratio, a pH of 10, and 3 h of treatment at 70 °C. The use of HPH and pH 12-shifting methods resulted in a remarkable 2.5-fold increase in grafting degree, requiring less processing time. Fourier transform infrared spectra confirmed the formation of conjugates. Conjugates produced through HPH with pH 12-shifting (MPHX) transformed into soluble glycoproteins with a particle size of 74 nm. MPHX solubility increased by 5.7-fold than HPC, reaching 85.7%, with a more negatively charged surface at -32.4 mV. Microimages showed cracked and sharp forms for conjugated proteins compared to untreated HPC. Additionally, MPHX conjugates demonstrated superior properties in emulsion stability, foaming capacity, and antioxidant activity compared to HPC and classical conjugates. The use of HPH and pH-shifting-assisted Maillard conjugation was highly effective in enhancing the functional attributes of hemp protein conjugates. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Structural and sensory characteristics of ultrasonic assisted wet-heating Maillard reaction products of Giant salamander protein hydrolysates.

Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet-heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet-heating MR on the structure and flavor of CGSPH was investigated in the present study. The results indicated that the ultrasound assisted wet-heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet-heating MRPs. Moreover, ultrasound assisted wet-heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet-heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan-2-carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet-heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry.

Improving the performance and long-term durability of high-temperature PEMFCs: A polyvinylpyrrolidone grafting modification strategy of polybenzimidazole membrane

This study introduces an innovative approach to graft Polyvinylpyrrolidone (PVP) onto Polybenzimidazole (PBI) to synthesise Proton Exchange Membranes (PEMs) with high performance and durability. As a widely used hydrophilic polymer in industry, PVP can add numerous nitrogen-containing functional groups to the membrane to enhance its phosphoric acid (PA) binding ability. In this work, Polybenzimidazole-graft-polyvinylpyrrolidone (PVP-g-PBI) polymers with varying grafting degrees were synthesized and tested to investigate the impact of the grafting modification on the membrane's proton conductivity, thermal properties, and electrochemical performance. With the introduction of PVP side chains, the fuel cell showed enhanced PA uptake and substantial improvements in peak power density. Notably, PBI-g-PVP membranes with a grafting degree of 22.4 % achieved a peak power density enhancement up to 1312 mW cm⁻2 at 160 °C, a 59.6 % increase over pristine PBI membranes. Due to the increased PA binding sites in the membrane, the PBI-g-PVP PEMs exhibit better PA adsorption ability and long-term durability than pristine membranes. The accelerated stress test (AST) demonstrated that the PBI-g-PVP membranes maintain a peak power density of 1105 mW cm⁻2 after a 70-h test, equivalent to 183.9 % of the pristine PBI membrane. The improved fuel cell performance and durability of PBI-g-PVP PEMs underscore the potential of this grafting strategy.