Gel Permeation Chromatography Research Articles

Kenaf Seed Cysteine Protease (KSCP) Inhibits the Intrinsic Pathway of the Blood Coagulation Cascade and Platelet Aggregation.

Thrombosis is the key event that obstructs the flow of blood throughout the circulatory system, leading to stroke, myocardial infarction and severe cardiovascular complications. Currently, available antithrombotic drugs trigger several life-threatening side effects. Antithrombotic agents from natural sources devoid of adverse effects are grabbing high attention. In our previous study, we reported the antioxidant, anticoagulant and antiplatelet properties of kenaf seed protein extract. Therefore, in the current study, purification and characterization of cysteine protease from kenaf seed protein extract responsible for potential antithrombotic activity was undertaken. Purification of KSCP (Kenaf Seed Cysteine Protease) was carried out using gel permeation and ion exchange column chromatography. The purity of the enzyme was evaluated by SDS PAGE (Sodium Dodecyl-Sulfate Polyacrylamide Gel Electrophoresis). RP-HPLC (Reverse Phase High-Performance Liquid Chromatography), MALDI-TOF (Matrix-Assisted Laser Desorption Ionization Time-Of-Flight) and CD (Circular Dichroism techniques) were employed for its characterization. Proteolytic, fibrinolytic and kinetic study was done using spectroscopy. Plasma recalcification time, Prothrombin Time (PT), Thrombin clotting time (TCT), Activated Partial Thromboplastin Time (APTT), bleeding time and platelet aggregation studies were carried out for antithrombotic activity of KSCP. A single sharp band of KSCP was observed under both reduced and non-reduced conditions, having a molecular mass of 24.1667kDa. KSCP was found to contain 30.3% helix turns and 69.7% random coils without a beta-pleated sheet. KSCP digested casein and fibrin, and its activity was inhibited by iodoacetic acid (IAA). KSCP was optimally active at pH 6.0 at the temperature of 40°C. KSCP exhibited anticoagulant properties by interfering in the intrinsic pathway of the blood coagulation cascade. Furthermore, KSCP dissolved both whole blood and plasma clots and platelet aggregation. KSCP purified from kenaf seed extract showed antithrombotic potential. Hence, it could be a better candidate for the management of thrombotic complications.

Linking Chemical Structure to the Linear and Nonlinear Properties of Asphalt Binders

The study described in this paper aims to establish the relationship between the chemical composition and rheological properties of asphalt binders in both the linear viscoelastic (LVE) and nonlinear viscoelastic (NLVE) domains. Two asphalt binders with different penetration grades were subjected to four distinct aging treatments of varying severity, resulting in changes in their chemical fingerprints. Chemical characteristics of the asphalt binders were analyzed using thin-layer chromatography (TLC), Fourier Transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Frequency sweep tests were conducted to evaluate the LVE behavior of the asphalt binders, while multiple stress creep recovery (MSCR) tests were employed to assess their NLVE properties. With regard to the LVE properties, rheological index ( R) and zero shear viscosity (ZSV) derived from the Christensen-Anderson-Marasteanu (CAM) model exhibited high correlations with FTIR and molecular weight distribution (MWD) parameters. Additionally, the polydispersity index (PDI) displayed a stronger correlation with LVE-based parameters. Findings from the MSCR tests revealed that the sensitivity of the percentage recovery ( %R) to chemical composition, as opposed to nonrecoverable creep compliance ( Jnr), can be largely attributed to the degree of nonlinearity. Furthermore, it was observed that lower molecular weight molecules exert a greater influence on %R in the nonlinear domain. Finally, it was found that Jnrslope is a more reliable parameter than Jnrdiff for assessing the effects of chemical makeup on stress and temperature sensitivity.

Non‐isocyanate polyurethane‐acrylate as UV‐ and thermo‐responsive plasticizer for thermoplastic elastomer

AbstractA UV‐ and thermo‐responsive polyurethane‐acrylate prepolymer was synthesized from palm olein (POo) via a non‐isocyanate route. The process included epoxidation of POo, carbonation of epoxidized palm olein (EPOo) into polycyclic carbonate in a solvent‐free and mild condition (100°C, 1 atm), followed by reacting with ethylene diamine and acrylic acid. The chemical structure of the non‐isocyanate polyurethane‐acrylate (NIPUA) prepolymer was elucidated by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform‐infrared spectroscopy (FTIR), while weight average molecular weight of NIPUA was determined by gel permeation chromatography (GPC). The NIPUA (0–20 wt%) was incorporated with thermoplastic elastomer (TPE) as a plasticizer and cured under UV light and thermal stimulations. The cured NIPUA/TPE films were characterized by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test. Under UV and thermal stimulations, the NIPUA/TPE demonstrated enhanced tensile properties (elongation at break >1280%, Young's modulus ~25 MPa), thermal properties (lower Tg), lower water contact angle, and shortened curing time as compared with the blank TPE. The 20 wt% NIPUA/TPE films exhibited susceptibility to enzymatic biodegradation and noncytotoxic to HEK 293 cells in vitro, demonstrated it's potential as a UV‐ and thermo‐responsive plasticizer for TPE in manufacturing of medical devices.

Extraction of Pithecellobium clypearia Benth polysaccharides by dual-frequency ultrasound-assisted extraction: Structural characterization, antioxidant, hypoglycemic and anti-hyperlipidemic activities

In this research, the extraction process of polysaccharides from Pithecellobium clypearia Benth (PCBPs) was optimized using dual-frequency ultrasound-assisted extraction (DUAE). The biological activities of PCBPs were investigated by in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic assay. High-performance anion-exchange chromatography, high-performance gel permeation chromatography, SEM, UV–Vis spectroscopy, and FT-IR spectra were used to analyze the monosaccharide composition, molecular weight, microscopic morphology, and characteristic structure of PCBPs. The results showed that the maximum extraction rate of PCBPs was 9.90 ± 0.16% when the ultrasonic time was 8 min, the liquid-to-material ratio was 32 mL/g, and the ultrasonic power was 510 W. The PCBPs also possessed excellent in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic activities. In addition, the average molecular weight of PCBPs was 15.07 kDa. PCBPs consisted of rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid, with the molar ratios of 11.07%, 18.54%, 48.17%, 10.44%, 4.62%, 4.96%, and 2.20%, respectively. Moreover, the results of SEM showed that PCBPs mainly showed a fine spherical mesh structure. The above studies provided a valuable theoretical basis for the subsequent in-depth study of PCBPs.

Synthesis and Characterization of Graft Copolymers with Poly(ε-caprolactone) Side Chain Using Hydroxylated Poly(β-myrcene-co-α-methyl styrene).

Graft copolymers have unique application scenarios in the field of high-performance thermoplastic elastomers, resins and rubbers. β-myrcene (My) is a biomass monomer derived from renewable plant resources, and its homopolymer has a low glass transition temperature and high elasticity. In this work, a series of tapered copolymers P(My-co-AMS)k (k = 1, 2, 3) were first synthesized in cyclohexane by one-pot anionic polymerization of My and α-methyl styrene (AMS) using sec-BuLi as the initiator. PAMS chain would fracture when heated at high temperature and could endow the copolymer with thermal degradation property. The effect of the incorporation of AMS unit on the thermal stability and glass transition temperature of polymyrcene main chain was studied. Subsequently, the double bonds in the linear copolymers were partially epoxidized and hydroxylated into hydroxyl groups to obtain hydroxylated copolymer, which was finally used to initiate the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) to synthesize the graft copolymer with PCL as the side chain. All these copolymers before and after modifications were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), thermogravimetry analysis (TGA), and differential scanning calorimeter (DSC).

Effect of Oligoricinoleic Acid on Degradation of Polylactic Acid

ABSTRACT The objective of this research is to explore the impact of oligoricinoleic acid (ORA) on the degradation of polylactic acid (PLA). ORA was synthesized from ricinoleic acid using tin (II) 2-ethylhexanoate as a catalyst. The chemical structures of the obtained ORA were confirmed by Fourier-transform infrared spectrometer (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). PLA/ORA films were prepared through the casting method by varying ORA concentrations as 0.1%wt, 0.3%wt, 0.5%wt, 1.0 wt%, and 3.0%wt. Degradation of the films via hydrolysis was studied by soaking the films in deionized water and stirring at 120 rpm in an incubator at 37°C. Alterations in the structure and properties of the films were investigated after soaking for 7, 14, 21, and 28 days using ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and universal testing machine (UTM). Gel permeation chromatography (GPC) was performed to confirm the decrease in molecular weight (MW). The presence of 3%wt ORA could promote both ductility and degradation of PLA films. ORA further enhances thermal stability, indicating potential for prevention of thermal degradation during melt processing.

Inhibition of LPS-Induced Skin Inflammatory Response and Barrier Damage via MAPK/NF-κB Signaling Pathway by Houttuynia cordata Thunb Fermentation Broth.

Houttuynia cordata Thunb is rich in active substances and has excellent antioxidant and anti-inflammatory activity. Scanning electron microscopy and gel permeation chromatography were used to analyze the molecular characteristics of the fermentation broth of Houttuynia cordata Thunb obtained through fermentation with Clavispora lusitaniae (HCT-f). The molecular weight of HCT-f was 2.64265 × 105 Da, and the polydispersity coefficient was 183.10, which were higher than that of unfermented broth of Houttuynia cordata Thunb (HCT). By investigating the active substance content and in vitro antioxidant activity of HCT-f and HCT, the results indicated that HCT-f had a higher active substance content and exhibited a superior scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radicals and hydroxyl radicals, with IC50 values of 11.85% and 9.01%, respectively. Our results showed that HCT-f could effectively alleviate the increase in the secretion of inflammatory factors and apoptotic factors caused by lipopolysaccharide (LPS) stimulation, and had a certain effect on repairing skin barrier damage. HCT-f could exert an anti-inflammatory effect by down-regulating signaling in the MAPK/NF-κB pathway. The results of erythrocyte hemolysis and chicken embryo experiments showed that HCT-f had a high safety profile. Therefore, this study provides a theoretical basis for the application of HCT-f as an effective ingredient in food and cosmetics.

Performance evolution and mechanism of asphalt crack sealant under UV aging: A continuity study

Asphalt crack repair materials, known as crack sealants, are directly exposed to ultraviolet (UV) radiation in asphalt pavements. This exposure causes the gradual aging and deterioration of both their surface and internal properties. To study this phenomenon, the sealant was subjected to UV irradiation for a range of 0–385 hours, with the basic properties of the aged sealant tested every 55 hours. Several techniques were employed to investigate the changes in the internal chemical composition of the sealant, including Fluorescence microscopy (FM), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FT-IR). The results revealed that the UV aging of the sealant mainly occurs in the thinner surface layer, which becomes progressively lighter in color. Notably, obvious surface cracks form after aging process. The cone penetration and softening point of the sealant exhibit an exponential or logarithmic change corresponding to the aging time. The most pronounced changes occur during the early stages of UV aging, with the properties tending to stabilize after approximately 220 h of aging. In addition, the FM images showed that the dispersed polymer particles within the sealant gradually transform into a continuous network structure after aging over time. The GPC spectrum of the aged sealant shifts to the left, indicating an increase in molecular weight, particularly in the polymer modifier. This is consistent with the transformation observed in the FT-IR analysis, which demonstrates that UV irradiation leads to the breaking and recombination of polymer chemical bonds in the sealant. The FT-IR analysis reveals the conversion of monosubstituted benzene to polysubstituted benzene in the polymer modifier, which also correlates with the formation of the network structure observed in the FM images and the increase in molecular weight detected in the GPC spectrum of the polymer modifier.

Biodegradation of low-density polyethylene film by two bacteria isolated from plastic debris in coastal beach

Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film's surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.

Relationship between dietary fiber content and prebiotic potential of polysaccharides from the seaweeds of the North west coast of India

The macroalgae are a sustainable bioresource that can be harnessed for their functional food and nutraceutical applications. This study characterized the biochemical composition and bioactive potential of natural biological macromolecules, such as macroalgal polysaccharides extracted using a green, aqueous extraction process. The in-vitro antioxidant and antiglycemic activity of these polysaccharides were evaluated using model, free radical and antiglycemic compounds. The prebiotic potential of macroalgal polysaccharides were analysed based on their ability to promote the growth of two potential probiotic bacteria Lactobacillus acidophilus and L. bulgaricus and suppress the growth of enteric bacteria, Escherichia coli. Among the polysaccharides studied, the brown algal polysaccharide MPS8 MPS9 and MPS10 exhibited good antioxidant, antiglycemic and prebiotic activity. Based on infrared spectroscopy, the functional groups sulfation and carboxylation were identified in potential polysaccharides. The monosaccharide composition in the bioactive polysaccharides was determined using High Performance Anion Exchange Chromatography Pulse Amperometric detector (HPAEC-PAD). These bioactive polysaccharides were fractionated using ion exchange chromatography to purify it and further characterized using gel permeation chromatography and NMR spectroscopy. The results these polysaccharides are mainly composed of fucose and glucose which is due to the fucoidan and laminarin, respectively. Such macromolecules with high dietary fiber content and bioactivity are in global demand as functional food, nutraceutical and pharmaceutical formulations.

Polymer-type flame retardants based on a DOPO derivative for improving the flame retardancy of polyamide 6: Preparation, properties and flame retardancy mode of action

A polymer-type flame retardant (PFR) based on a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative was synthesised here to improve the flame retardancy of polyamide 6 (PA6). The chemical structure and thermal property of the PFR were characterised by Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PFR and PA6 were melt-blended to obtain a flame-retardant polyamide 6 (FRPA6). Its thermal property, mechanical property and flame retardancy were characterised via TGA, DSC and tensile, impact, vertical burning and limiting oxygen index (LOI) tests. Its flame-retardant mode of action was analysed by scanning electron microscopy, FTIR spectroscopy, cone calorimetry and pyrolysis-gas chromatography-mass spectrometry. The FRPA6 with a phosphorus content of 3000 ppm passed the UL-94 V-0 rating, and the LOI of the FRPA6 with a phosphorous content of 5000 ppm reached 28.8 %. Compared with pure PA6, the peak heat release rate, total heat release and effective heat of FRPA6–5000 were reduced by 35.4 %, 21.9 % and 26.5 %, respectively. These results indicate that the flame-retardant mode of action of PFR mainly involved the quenching effect of phosphorus-containing radicals in the gas phase.

Evaluation of the polycaprolactone hydrolytic degradation in acid solvent and its influence on the electrospinning process

AbstractPolycaprolactone (PCL) is a pivotal biopolymer in biomedicine, especially in tissue engineering for scaffolds and biomaterials. Recognized for its effectiveness as a drug carrier with superior controlled release properties, PCL is commonly processed via electrospinning, typically employing chlorinated or fluorinated solvents known for cellular toxicity. As an environmentally conscious alternative, this study explores glacial acetic acid (AA) as a solvent for electrospinning solutions. Investigating PCL's molecular degradation through acid hydrolysis in acidic solvents (AA/formic acid) (FA), the study assesses the impact of storage time on resulting structures. Solutions containing 30% PCL in AA/FA (9:1) were stored at 35°C for up to 14 days, revealing a 50% molar mass reduction during solubilization through gel permeation chromatography, x‐ray diffraction, and Fourier‐transform infrared analyses. This reduction influenced chain packing, raising crystallinity indices from approximately 37% to 49% with prolonged storage. The reduced molar mass resulted in unstable Taylor cones, generating diverse mat morphologies. Intriguingly, this degradation enhanced water adsorption capacity, indicating exposed hydrogen bonds from acid hydrolysis as an advantageous trait for regenerative medicine. This underscores the hydrolyzed materials' potential for cell anchoring in tissue engineering.

Preparation and photocuring performance of itaconic acid-derived hyperbranched macromers with internal and terminal C[dbnd]C bonds catalyzed by tetramethylguanidine

A series of hyperbranched polymers derived from biomass itaconic acid was prepared via aliphatic nucleophilic substitution polycondensation reaction under mild conditions by using bis(2-bromoethyl) itaconate and trimeric acid as A2 and B3 monomers, respectively, and tetramethylguanidine as catalyst. On this basis, the hyperbranched macromers that contained C = C double bonds in the internal skeleton and the periphery were obtained by further adding A1 monomer (2-bromoethyl acrylate) directly into the reaction system. The successful synthesis of these macromers were confirmed via proton nuclear magnetic resonance, Fourier transform infrared and gel permeation chromatography. The results of photo-differential scanning calorimetry and rheological experiments showed that these macromers exerted a positive effect on the ultraviolet (UV) curing of commercial resin. The properties of cured splines and coatings, such as mechanical properties, pencil hardness, and thermal stability, were considerably improved with the addition of hyperbranched macromers. They were significantly better than those of linear macromers and macromers that contained polymerizable groups only in the inner framework or their terminal units. The results show that both the inner and terminal C = C double bonds of hyperbranched macromers can participate in UV cross-linking. Thus, such macromers may be used as potential additives for high-performance UV curable coatings.

Interaction of composite fume suppression and odor elimination agents with crumb rubber modified asphalt: Inhibition behavior of volatile organic compounds (VOCs) and inorganic fume

The production and construction of crumb rubber modified asphalt (RMA) at high temperatures can produce a large amount of toxic fume, which is detrimental to human health and environment. In this study, a series of composite fume suppression and odor elimination agents (CSEAs) with both physical adsorption and chemical capture functions were adopted to reduce the emissions of volatile organic compounds (VOCs) and hydrogen sulfide (H2S). The material composition, microstructure, and specific surface area of CSEA were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and N2 adsorption-desorption isotherm (BET). The inhibitory effects of adding CSEA on toxic fume emissions from RMA at high temperatures were investigated through a combination of fume emission tests, H2S gas detection, gel permeation chromatography (GPC), and gas chromatography–mass spectrometry technology (GC–MS). The adsorption behavior of CSEA on H2S was analyzed through adsorption dynamics. Results showed that the physical and chemical properties of CSEA are stable while chemical adsorption dominates the CSEA's effect on H2S. ZnO and Ca(OH)2 exhibit good crystallization effects on the surface of the carrier by forming mesoporous structures mostly above 3.4 nm in size. The incorporation of CSEA significantly reduced the total emissions of RMA fume and the main components of VOCs in which the average inhibition rate of H2S can reach 44 % at an initial 30 mins.

Basic characterization of three kinds of bio-asphalt and research on the low-temperature performance of bio-asphalt mixtures

Bio-oil is a by-product of waste biomass treatment using high-pressure liquefaction, bio-enzymatic, or high-temperature thermal cracking techniques, and can alleviate the shortage of petroleum asphalt resources. This study investigated the production of bio-oil from selected raw materials, including corn stover, castor oil from castor beans, and epoxy vegetable oil from soybeans for the preparation of bio-asphalt. The properties and mechanisms of modification of the three modified bio-asphalts were explored by assessment of basic physical properties, gel permeation chromatography (GPC), temperature scanning (DSR), and thermogravimetric analysis, as well as Semi-Circular Bending (SCB), low-temperature bending, and fatigue tests. Bio-oil was found to improve the low-temperature cracking resistance of the asphalt mixtures, with the improvement further enhanced by changing the blending amount. The bio-oil was observed to negatively affect the low-temperature fatigue performance of the mixes, and the decrease in the n-value indicated that the bio-oil could make the asphalt mixtures less stress-sensitive under repeated loading, with improved anti-fatigue performance of bio-asphalt mixtures observed when the stress ratio was 0.5. Finally, the low-temperature cracking performance index of the corn stover bio-asphalt mixtures was correlated with the gray entropy. The use of the SCB fracture index was found to be more appropriate when using the semicircular bending test to characterize the low-temperature cracking performance of bio-asphalt mixtures.

Ionic liquid-assisted pretreatment of lignocellulosic biomass using purified Streptomyces MS2A cellulase for bioethanol production

In recent years, the process of producing bioethanol from lignocellulosic biomass through biorefining has become increasingly important. However, to obtain a high yield of ethanol, the complex structures in the feedstock must be broken down into simple sugars. A cost-effective and innovative method for achieving this is ionic liquid pre-treatment, which is widely used to efficiently hydrolyze the lignocellulosic material. The study aims to produce a significant profusion of bioethanol via catalytic hydrolysis of ionic liquid-treated lignocellulose biomass. The current study reports the purification of Streptomyces sp. MS2A cellulase via ultrafiltration and gel permeation chromatography. The kinetic parameters and the biochemical nature of the purified cellulase were analyzed for the effective breakdown of the EMIM[OAC] treated lignocellulose chain. The two-step cellulase purification resulted in 6.28 and 12.44 purification folds. The purified cellulase shows a Km value of 0.82 ± 0.21 mM, and a Vmax value of 85.59 ± 8.87 μmol min−1 mg−1 with the catalytic efficiency of 1.027 S−1. The thermodynamic parameters like ΔH, ΔS, and ΔG of the system were studied along with the thermal deactivation kinetics of cellulase. The optimal temperature and pH of the purified cellulase enzyme for hydrolysis was found to be 40 °C and 7. The rice husk and wheat husk used in this study were pretreated with the EMIM [OAC] ionic liquid and the change in the structure of lignocellulosic biomass was observed via HRSEM. The ionic liquid treated biomass showed the highest catalytic hydrolysis yield of 106.66 ± 0.19 mol/ml on the third day. The obtained glucose was fermented with Saccharomyces cerevisiae to yield 23.43 g of ethanol/l of glucose from the rice husk (RH) and 24.28 g of ethanol/l of glucose from the wheat husk (WH).

Low molar mass polycarbonate diols from degradation of terpolymers obtained by epoxide/o-phthalaldehyde/CO2 copolymerization

In this manuscript, we describe the synthesis of low molar mass polycarbonate diols by acid cleavage of labile acetal linkages included in high molar mass poly(ether-co-carbonate-co-acetal) terpolymers. These copolymers were prepared by terpolymerization of propylene oxide (PO) with o-phthalaldehyde (OPA) and carbon dioxide (CO2), using triethyl borane (TEB) as activator and an onium salt as initiator. The advantage of this strategy of synthesis of poly(propylene carbonate) diols (PPC-diols) lies in the minute amounts of TEB and initiator required. Moreover, OPA could be isolated through post-hydrolysis of the terpolymers and recycled for subsequent use. We also demonstrated that this strategy works for the synthesis of low molar mass poly(ethylene carbonate) diols (PEC-diols). The structural integrity of the terpolymers before and after acid treatment, the characterization of low molar mass PPC-diols, and recycling process of OPA were carried out by 1H NMR spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption ionization time of flight (MALDI-TOF) MS.

Unveiling the ability of protic and aprotic ionic liquids to dissolve and modify Kraft lignin

Lignin, a renewable macromolecule abundant in lignocellulosic biomass, holds significant promise as a renewable source for producing biofuels, biomaterials, and fine chemicals, offering a potential avenue to reduce dependence on petroleum-derived products. However, the lignin complex structure poses challenges for its effective utilization, often requiring some special treatments. In recent decades, ionic liquids (ILs) have been pointed out as promising candidates for lignin processing due to their appealing properties, which include low vapor pressure/flammability, high chemical and thermal stability, and efficacy as lignin solvents. ILs may be categorized as protic (PILs) or aprotic ionic liquids (AILs), and these two classes offer distinct advantages. PILs are readily synthesized by mixing an acid and a base in stoichiometric proportions, forming a mixture containing neutral species that remain in equilibrium with cations and anions. In contrast, AILs present cations with enduring positive charges and are not in equilibrium with their precursors as the PILs, though AILs are frequently more expensive and challenging to produce. Within the biorefinery context, the ability to dissolve Kraft lignin is pivotal for developing new strategies and technologies. Moreover, chemical transformations may occur during lignin dissolution in IL solutions. In this study, the solubility of Kraft lignin was evaluated in four neat imidazolium-based AILs, five neat pyrrolidinium-based PILs, and in aqueous solutions of these ILs, at 313.2 K. The highest solubility value ((77.71 ± 1.03) wt%) was observed for pyrrolidinium octanoate (PIL), while 1-butyl-3-methylimidazolium methyl sulfate exhibited the highest solubility ((73.93 ± 1.27) wt%) among the studied AILs. Whenever possible, the solubilities measured in the present work were critically compared with data available in the literature. Finally, lignin recovered from the IL solutions was analyzed by Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (NMR) spectroscopy to assess the solvent ability to induce structural modifications in this macromolecule. The analysis revealed that ILs effectively cleaved β-O-4 linkages in lignin molecules, and concurrent condensation reactions might increase the precipitated lignin molecular weight.

Variation pattern in the macromolecular (cellulose, hemicelluloses, lignin) composition of cell walls in Pinus tabulaeformis tree trunks at different ages as revealed using multiple techniques

The plant cell wall is a complex, heterogeneous structure primarily composed of cellulose, hemicelluloses, and lignin. Exploring the variations in these three macromolecules over time is crucial for understanding wood formation to enhance chemical processing and utilization. Here, we comprehensively analyzed the chemical composition of cell walls in the trunks of Pinus tabulaeformis using multiple techniques. In situ analysis showed that macromolecules accumulated gradually in the cell wall as the plant aged, and the distribution pattern of lignin was opposite that of polysaccharides, and both showed heterogenous distribution patterns. In addition, gel permeation chromatography (GPC) results revealed that the molecular weights of hemicelluloses decreased while that of lignin increased with age. Two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) analysis indicated that hemicelluloses mainly comprised galactoglucomannan and arabinoglucuronoxylan, and the lignin types were mainly comprised guaiacyl (G) and p-hydroxyphenyl (H) units with three main linkage types: β-O-4, β-β, and β-5. Furthermore, the C-O bond (β-O-4) signals of lignin decreased while the C-C bonds (β-β and β-5) signals increased over time. Taken together, these findings shed light on wood formation in P. tabulaeformis and lay the foundation for enhancing the processing and use of wood and timber products.

Evaluation of Modified Asphalt Binders with Soybean Oil-Based Polymers: Preparation Temperature and Rheological Characterization

To investigate the feasibility of bio-based polymers in the modification of base asphalt binder, two soybean oil-based polymers (PAESO) were synthesized from bio-monomers with different functionalities via free radical polymerization. The characterization of both PAESOs was conducted using Hydrogen nuclear magnetic resonance and Gel Permeation Chromatography analyses, the results showed that the bio-monomer with a higher functionality exhibited a stronger tendency towards self-polymerization, resulting in the polymer with a high conversion rate (44.44 %) and a slightly lower molecular weight (14.76 kDa). The optimal mixing temperature for preparing PAESO-modified asphalt binders was determined through Molecular Dynamics (MD) simulation and Laser Scanning Confocal Microscopy. The MD simulation results indicated that PAESO-modified asphalt models had reached the most stable configurations at a mixing temperature of 160 °C, as evidenced by fewer and more homogeneous distributed small bright spots observed in fluorescence images. This suggested that the outstanding compatibility between PAESO and asphalt binders could be obtained at the optimal mixing temperature of 160 °C. Furthermore, the rheological characteristics of asphalt binders modified with PAESO were examined through Dynamic Shear Rheometer and Bending Beam Rheometer tests. The results revealed that PAESO mainly exhibited a softening effect by significantly enhancing the flexibility, stress relaxation, fatigue, and thermal cracking resistance of the base asphalt binders at intermediate and low temperatures. PAESO-L modified asphalt manifested elastic properties akin to those observed in polymer-modified asphalt within the low-frequency and high-temperature domain. Additionally, PAESO derived from monomers with a higher functionality presented notable benefits in enhancing thermal and fatigue cracking resistance than that of PAESO with a lower functionality. These findings provide valuable insights for the preparation and development of bio-polymer additives for use in asphalt materials.