Gel Permeation Chromatography Research Articles

Preparation and characterization of poly(ethylene glycol)-b-poly(tert-butyl methacrylate) micelles as potential nanocarriers for donepezil

Polymeric micelles were prepared for the delivery of donepezil, a leading Alzheimer’s disease drug, to enhance its transport across the blood–brain barrier (BBB). Poly(ethylene glycol)-b-poly(tert-butyl methacrylate) amphiphilic block copolymers were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were characterized by gel permeation chromatography and nuclear magnetic resonance spectroscopy. Empty and donepezil loaded polymer micelles were formed using the dialysis method and characterized by dynamic light scattering and transmission electron microscopy. Drug loading efficiency and release behavior were monitored using UV/Vis spectroscopy, and cytotoxicity was evaluated via colorimetric tests and impedance measurements. Additionally, the permeability of the nanocarriers across an in vitro BBB culture model was assessed. Drug-loaded micelles demonstrated similar permeability to free donepezil but offered sustained release and improved stability. This micellar delivery system holds significant potential for improving therapeutic outcomes in Alzheimer’s treatment by enhancing donepezil’s delivery across the BBB. Improved BBB permeability and sustained drug release could lead to more effective concentration of the drug in the brain, potentially reducing peripheral cholinergic side effects, such as nausea and vomiting, often observed with traditional donepezil administration. This could result in better patient compliance and improved cognitive outcomes, making this nanocarrier system a promising alternative for Alzheimer’s therapy.

Structure and characterization of an extracellular polysaccharide from Paenibacillus polymyxa 88A.

Levan-type polysaccharides, produced by various organisms, are nontoxic, biocompatible, and biodegradable polymers with a wide range of biological activities. They have high potential for use in medicine, cosmetology, and industry. A large amount of levan (41.1 g L-1) was recovered by ethanol precipitation from a liquid nutrient medium of Paenibacillus polymyxa 88A that contained 15 % w/v sucrose as a carbon source. The levan was fractionated by gel-permeation and anion-exchange chromatography and was analyzed by DRIFT and NMR spectroscopy. It was found that levan was represented by slightly branched chains composed of β-(2→6)-Fruf residues. The average molecular mass of the levan was about 1.9 MDa. When shear stress was applied at different temperatures, aqueous levan solutions showed pseudoplastic behavior. As found by SEM, a freeze-dried powdered levan sample had a microporous structure. The levan had excellent emulsifying activity toward sunflower oil, forming an emulsion with long-term stability. Analysis of the antioxidant activity of the levan showed a higher, dose-dependent activity toward ABTS, as compared with that toward DPPH. Finally, the bioactivity of the levan was examined by MTT assay by using human cervical carcinoma (HeLa) cells.

Preparation of viscosity-reducing polycarboxylate superplasticizer (PCE) and its role in low water-to-cement ratio system

Owing to the low water-cement ratio (less than 0.25) of ultra-high-performance concrete (UHPC) materials, the system exhibits increased viscosity, diminished slurry flow, and challenges in pouring during the construction process, which compromise its workability. Consequently, the development of highly efficient viscosity-reducing polycarboxylate superplasticizer (PCE) is of paramount importance. In this study, we synthesized a series of viscosity-reducing polycarboxylate superplasticizers(JN-PCE) utilizing allyl polyethylene glycol ether (APEG), acrylic acid (AA), and sodium methallyl sulfonate (SMAS) as raw materials through the process of free radical polymerization. Fourier-transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and energy-dispersive X-ray spectroscopy were employed to characterize the materials. Subsequent evaluations of surface tension, fluidity, adsorption performance, and Marsh time demonstrated that these superplasticizers exhibited commendable dispersion and remarkable viscosity-reducing properties within a low water-cement ratio system. At a water-cement ratio of 0.18, the Marsh time of the JN-type PCE was reduced by 40% while maintaining the same fluidity, thereby underscoring the effective viscosity-reducing capabilities of the synthesized polycarboxylate superplasticizer.

High-Strength, Self-Healing Copolymers of Acrylamide and Acrylic Acid with Co(II), Ni(II), and Cu(II) Complexes of 4′-Phenyl-2,2′:6′,2″-terpyridine: Preparation, Structure, Properties, and Autonomous and pH-Triggered Healing

The utilization of self-healing polymers is a promising way of solving problems associated with the wear and tear of polymer products, such as those caused by mechanical stress or environmental factors. In this study, a series of novel self-healing, high-strength copolymers of acrylamide, acrylic acid, and novel acrylic complexes of 4′-phenyl-2,2′:6′,2″-terpyridine [Co(II), Ni(II), and Cu(II)] was prepared. A systematic study of the composition and properties of the obtained polymers was carried out using a variety of physicochemical techniques (elemental analysis, gel permeation chromatography (GPC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR), ultraviolet-visible spectroscopy (UV-vis), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), confocal laser scanning microscopy (CLSM), and tensile testing). All metallopolymer samples exhibit autonomous intrinsic healing along with maintaining high tensile strength values (for some samples, the initial tensile strength exceeded 100 MPa). The best values of healing efficiency are possessed by metallopolymers with a nickel complex (up to 83%), which is most likely due to the highest lability of the metal–heteroatom coordination bonds. The example of this system shows the ability to re-heal with negligible deterioration of the mechanical properties. The possibility of tuning the mechanical properties of self-healing films through the use of different metal ions has been demonstrated.

Methyl jasmonate improves rubber production and quality in Lactuca Serriola.

The increase in demand for natural rubber has led to the search for alternative sources. Lactuca serriola is emerging as a promising candidate, as the quality of the natural rubber it produces is comparable to that of the Pará Rubber Plant, Hevea brasiliensis. This study examines the effect of methyl jasmonate (MeJA), a known elicitor, on the expression of key rubber biosynthesis pathway genes (HMGR1, HMGS1, CPT2, and SRPP1) in the latex of L. serriola plants. The expression levels of these genes increased significantly after the foliar application of 200 and 400 µM MeJA. The highest relative expression level for HMGR1, HMGS1, CPT2 and SRPP1 was 3.74, 18.56, 11.91and 16.59 fold respectively. Furthermore, the rubber content in L. serriola showed a significant rise post-treatment compared to the control with increasing the level of MeJA (6.19%, 7.24% and 7.85% which correspond to 0, 200 and 400 µM). Gel permeation chromatography revealed an augmentation in the molecular weight of extracted natural rubber from treated plants. Samples treated with 400 µM of MeJA had the highest molecular weight (1570 kg mol-1) compared to control (1186 kg mol-1). This study has demonstrated that MeJA, through the regulation of rubber biosynthesis genes, is capable of enhancing the quality and quantity of natural rubber extracted from alternative sources, such as L. serriola.

Comparative Analysis of the Compositions of the "Kerkuri" Resins with Different Ratios of the M And Q Units

The compositions and structures of methyl MQ resins with different M/Q ratios were studied using NMR and IR spectroscopy, as well as gel permeation chromatography (GPC). It was found that the M/Q ratio affects the molecular weight of the siloxanes under consideration and the activity of hetero- and homopolycondensation. Depending on the M/Q ratio, MQ resins can act as plasticizers or reagents.

Study on the Mechanism of Dictyophora duplicata Polysaccharide in Reducing Depression-like Behavior in Mice.

Depression is a prevalent worldwide mental health disorder that inflicts significant harm to individuals and society. Dictyophora duplicata is an edible fungus that contains a variety of nutrients, including polysaccharides. This study aims to investigate the monosaccharide composition and molecular weight of the Dictyophora duplicata polysaccharide (DDP-B1), followed by an exploration of its antidepressant effects in chronic unpredictable mild stress (CUMS) mice. Dictyophora duplicata was purified using a DEAE-52 column and an S-400 column to obtain DDP-B1. The monosaccharide composition and molecular weight of DDP-B1 were investigated via high-performance gel permeation chromatograph. Six-week-old C57BL/6 male mice were utilized for the CUMS modeling to evaluate the antidepressant efficacy of DDP-B1. Fluoxetine served as the positive control group. The depressive-like behaviors and brain pathology of mice were evaluated. Immunofluorescence (IF) staining, metabolomics analysis, and western blot were employed to further investigate the underlying mechanisms. DDP-B1 significantly alleviated the depression-like behavior of CUMS mice and increased the expression of SYN and PSD-95 in the mice's brains, which was further validated by western blot. Metabolomics analysis indicated a reduction in serum glutamate in CUMS mice following DDP-B1 treatment. Moreover, DDP-B1 treatment led to an increase in levels of GABAAR, BDNF, p-TrkB and p-p70S6K. DDP-B1 regulated abnormalities in the glutamatergic system, subsequently activated the BDNF-TrkB-mTOR pathway and mitigated the pathological manifestations of CUMS mice. This study validated the potential of DDP-B1 as an antidepressant medication and established a theoretical foundation for the development of fungi with similar properties.

Effect of Fiber Cross-Sectional and Surface Properties on the Degradation of Biobased Polymers.

Biobased polymers such as polylactic acid (PLA) and polybutylene succinate (PBS) break down naturally under certain environmental conditions. The efficiency of degradation can be linked directly to fiber surface properties, which influence polymer accessibility. Here, the degradation of PLA and PBS fibers with six different cross-sections was investigated. The fibers were aged by hydrolysis and UV exposure in an accelerated weathering test, followed by an ISO 20200 laboratory-scale disintegration test with non-aged fibers as controls. The polymers were analyzed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and gel permeation chromatography, comparing the polymer granulate, virgin fibers, and UV-exposed fibers. It was found that the molecular mass and crystallinity of PBS changed more than PLA during spinning. Several PLA samples were completely degraded, whereas all the PBS samples remained intact. Furthermore, surface openings appeared on the PLA fibers during weathering, suggesting greater sensitivity to UV exposure and hydrolysis than PBS. A clear correlation between the fiber surface area and the degradation rate was observed for all samples, but the correlation was positive for PLA and negative for PBS. The slower degradation of PBS fibers with a larger surface area may reflect the ability of PBS to preserve itself by further crystallization during degradation processes at temperatures higher than the glass transition point. The data clearly show that the analysis of single degradation mechanisms is insufficient to predict the behavior of material under real-world conditions, where different degradation mechanisms may work in parallel or consecutively, and may show interdependencies.

Optimizing corncob pretreatment with eco-friendly deep eutectic solvents to enhance lignin extraction and cellulose-to-glucose conversion

Deep eutectic solvents (DES) are an eco-friendly, cost-effective alternative to traditional ionic liquids for biomass pretreatment, with unique characteristics encompassed by hydrogen bond donor (HBD), the molar ratio of hydrogen bond acceptor (HBA) to HBD, temperature, and time affecting efficiency. Despite its potential, a comprehensive study exploring the interplay of these factors is limited. This study explores the optimization of pretreatment variables using choline chloride/lactic acid (1:5) via the response surface method (RSM). It aims to evaluate the effects of time and temperature on lignin extraction, cellulose-to-glucose conversion, and hemicellulose removal. Employing a 22 central composite design with temperature (80–140 °C) and time (2–6 h) as variables, optimal conditions were 123 °C for 6 h. Results include 90.08±1.42 % lignin extraction, 68.77±6.9 % cellulose-to-glucose conversion, and 77.34±0.85 % hemicellulose removal, with 52.52±8.07 % lignin recovery. The fractions of pretreated CC and lignin recovered in the optimal condition found were characterized by X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR), 1H, 13C, 2D-HSQC NMR spectroscopy, Thermogravimetric analysis (TGA/DTG), Gel Permeation Chromatography (GPC) to elucidate chemical characteristics of the materials obtained and facilitate downstream valorization. High efficiency was achieved in lignin extraction and cellulose conversion, and addressing solvent viscosity and DES recycling will further enhance the potential for industrial scalability.

Identification of new potential inhibitors of pteridine reductase-1 (PTR1) via biophysical and biochemical mechanism-based approaches: Step towards the treatment of Leishmaniasis

Leishmaniasis is a parasitic disease, which spreads from the bite of an infected Phlebotomine fly to human hosts. The disease is characterized by a number of clinical manifestations, such as ulcerative lesions at the site of sandfly bite (cutaneous form), inflammation of mucosal membranes (mucosal leishmaniasis) or the deadly visceral form. This study was aimed to target pteridine reductase-1 (PTR1), a member of short chain dehydrogenases, which accounts for the reduction of conjugated and unconjugated pterins in Leishmania parasite. The ptr1-pET28a+-tev construct was expressed using BL21 (DE3) cells, followed by two tandem purification steps including affinity and gel permeation chromatography. In the next phase, functional studies of PTR1 were performed via screening of an in-house library of 500 compounds. The biochemical-mechanism based assay of PTR1 identified 11 hits that were also found to be non-cytotoxic against human fibroblast cell line (BJ) (except compound 6), and thus further studied via computational technique and saturation transfer difference-nuclear magnetic resonance (STD-NMR) spectroscopy. These high throughput techniques identified six compounds 2, 4, 5, 7, 9, and 11 as active, which were then assessed via in-vitro assay. Among them, compounds 2, 4, and 7 showed substantial leishmanicidal activity, comparable to the standard drug, miltefosine (IC50 value: 31.8 ± 0.2 μM). These results narrowed down the search to 3 compounds as potential leads, with prominent protein-ligand interaction profiles. Hence, the respective compounds can be further assessed for their therapeutic potential against leishmaniasis.

Development of protein hydrolysate as a cost-effective and robust biodispersant: Investigating its performance in dispersing of carbon black pigment in water-based paints

Carbon black pigments hold significant importance as the primary representatives of black pigments in the industry today. The dispersibility of carbon black pigment (CB) in water is limited by the nonpolar and weakly hydrophilic characteristics of the pigment's surface. Therefore, there is a critical need to devise an economical and eco-friendly approach for creating a well-dispersed and stable suspension of carbon black in an aqueous medium. The primary focus of this study was to investigate the dispersion capabilities of protein hydrolysate (HP) derived from sheep wool on CB particles in a water-based pigment concentrate. The hydrolysis degree of protein source was determined by high-performance liquid chromatography and gel permeation chromatography. The dispersion performance was investigated by zeta potential, transmission electron microscopy, Fourier transform infrared spectroscopy, grindometer, spectrophotometer-colorimeter, viscometer, and cryptometer measurements. The HP solution containing amino acids, peptides, and polypeptides with low molecular weight can cover the surface of the CB particles, creating enough electrical repulsion and steric resistance. As a result, this phenomenon can inhibit the collision and interaction among the pigment particles caused by Brownian motion, making it less prone to aggregation. The protein hydrolysate demonstrated a higher capability in producing the stable CB dispersions compared to a commercial reference dispersant, highlighting the effectiveness of amino acids, peptides, and polypeptides as powerful CB dispersing agents.

Hydrolysis of Poly(ester urethane): In-depth Mechanistic Pathway Determination through Thermal and Chemical Characterization

Many structure/property relationships of hydrolyzed poly(ester urethane) (PEU) – a thermoplastic polymer have been reported. Examples include changes in molecular weight vs. elongation at break and crosslink density vs. mechanical strength. However, the effect of molecular weight reduction on some physical, thermal, and chemical properties of hydrolyzed PEU have not been reported. Therefore, a large set of hydrolyzed PEU (Estane®5703) samples were obtained from two aging experiments: 1) accelerated aging conducted under various environments (air, nitrogen, moisture) and at 64°C and below for almost three years, and 2) natural aging conducted under ambient conditions for more than four decades. The hydrolyzed samples were characterized via multi-detection gel permeation chromatography (GPC), thermogravimetric analysis (TGA), modulated differential scanning colorimetry (mDSC), UV-vis spectroscopy, nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy techniques. Hydrolysis of ester linkages in the soft-segments decreases both the molecular weight of the polymer and the melting point of Estane from ∼55°C to 39°C. Aging above this melting temperature (Tm), increased mobility of polymer chains and water diffusivity alter the PEU degradation pathway from those expected at aging temperatures below Tm and have significant bearing on the critical molecular weight (MC) at which the physical, chemical, thermal, and mechanical properties of Estane change abruptly. While a MC value of 20 kDa is found for PEU hydrolysis at mild temperatures (e.g., below 39°C), the MC increases with increasing aging temperature. To complement the existing structure/property relationships reported in the literature, more correlations are obtained, which include the effect of Mw on polydispersity, intrinsic viscosity (Mark-Houwink equation), UV extinction coefficient, and dn/dc (GPC analysis) values. Furthermore, we seek to augment previously reported aging models for PEU by developing a practical model with which the extent of degradation and material performance can be predicted based on aging under different temperature ranges both above and below the melting point of the hard-segments.

Phenacyl bromide as Norrish type I photoinitiator for the facile synthesis of chain-end functional PMMA and polystyrene

Phenacyl bromide has been explored as a new Norrish Type I photoinitiator for radically polymerizing methyl methacrylate and styrene monomers. A straightforward radical photopolymerization method using UVA light for the synthesis of chain-end functional poly(methyl methacrylate) and polystyrene has been developed. The process has been refined for both bulk and solution photopolymerizations. Chain-end functionalization was demonstrated by the formation of block-copolymers of the bromine-ended homopolymers, utilized as macroinitiators, resulting in an increase in the molecular weight of the corresponding precursor, observed by gel permeation chromatography (GPC). Block copolymerization was initiated by radicals generated at the chain-ends by a halogen-atom transfer reagent, namely, dimanganese decacarbonyl (Mn2(CO)10). This simple light-induced method is promising for the additive manufacturing field such as vat photopolymerization, stereolithography, digital light processing as it yields chain-end functional materials that can be further processed.

Structural Characterization and Anti-inflammatory Activities of a Purified Polysaccharide from Veronica persica Poir.

In this manuscript, the polysaccharide (VPP-I) from Veronica persica Poir., was characterized in detail by high performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). In addition, lipopolysaccharide (LPS) induced inflammation model of RAW264.7 cells was used to evaluate the in vitro anti-inflammatory activity of VPP-I. The results showed that the relative molecular weight of VPP-I was 2.355 KDa, which was mainly composed of mannose (Man), glucose (Glc) and galactose (Gal) in a ratio of 1 : 32.46 : 28.76. Moreover, the VPP-I contained sugar alcohol derivatives of T-DGlcp(1→, →4)-D-Galp(1→, →3,6)-D-Manp(1→, →4)-D-Glcp(1→, →6)-D-Galp(1→ and →6)-D-Glcp(1→. In vitro anti-inflammatory results showed that VPP-I could inhibit the secretion of IL-β, IL-6 and TNF-α in RAW264.7 cells induced by LPS. Moreover, compared to the LPS group, the mRNA expression levels of iNOS, COX-2, IL-β, IL-6 and TNF-α produced by RAW264.7 were significantly decreased after treatment with VPP-I (P<0.05). In addition, VPP-I could increase the SOD and GSH-Px enzymes activity and decrease the content of MDA in LPS-induced RAW264.7 cells (P<0.05). In summary, this paper laid theoretical foundation for the application of Veronica persica Poir. in the field of medicine.

Physical and Chemical Characterization of Sustainable Green Adhesives Derived from Municipal Treatment Plant Sludges

Adhesive formulations derived from sustainable feedstocks, like waste-activated sludge and biosolids from wastewater treatment plants, are developed due to protein-based adhesives receiving attention for their low-cost, resourcefulness, and minimal ecological footprint. The protein composition and associated dynamic changes of the adhesive formulations were studied via gel permeation chromatography, which detailed a molecular size distribution of 8.72 × 105 g/mol for the adhesive formulation and 6.89 × 103 g/mol for the dewatered biosolid base fraction, which confirms the formation of multiple protein functional groups combining to form the larger adhesive molecules. Further analysis determined the types of proteins present in the dewatered biosolids as glutelin, prolamin, globulin, and albumin proteins, with the glutelin proteins as the most prevalent, as thus likely responsible for adhesive formation. The rheological properties of the novel protein adhesive were also studied to interpret the structure of the adhesives, which detailed the findings of viscoelastic properties and flow behaviors of each adhesive in relation to the wastewater treatment plant sample location, which yielded higher flow points, storage moduli, and loss moduli for the dewatered biosolids in comparison to the waste-activated sludge and biosolid adhesives, which correlates with the higher solids content of the dewatered biosolids and potentially cell rupturing when exposed to filtration stress.

Closed-Loop Recycling of 3D-Printed Wood-PLA Composite Parts: Effects on Mechanical and Structural Properties via Fused Filament Fabrication.

This study investigated the closed-loop recycling of 3D-printed wood fiber (WF)-filled polylactic acid (PLA) composites via fused filament fabrication (FFF). The WF-PLA composites (WPCs) were extruded into WPC filaments (WPCfs) to produce FFF-printed WPC parts (WPCps). The printed WPCps were reprocessed three times via extrusion and 3D-printing processes. The tensile properties and impact strengths of the WPCfs and WPCps were determined. To further investigate the impact of closed-loop recycling on the surface morphology, crystallinity, and molecular weight of WPCfs, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively, were used. After closed-loop recycling, the surface morphology of the WPCfs became smoother, and a decrease in the pore sizes was observed; however, the tensile properties (tensile strength and elongation at break) deteriorated. With increasing numbers of recycling iterations, the molecular weight of the PLA matrix decreased, while an increase in crystallinity was observed due to the recrystallization of the low-molecular-weight PLA molecules after recycling. According to the SEM images of the recycled WPCps, their layer heights were inconsistent, and the layers were rough and discontinuous. Additionally, the color difference (ΔE*) of the recycled WPCps significantly increased. Compared with those of the WPCps after recycling them only once, the tensile strength, elongation at break, and impact strength of the WPCps noticeably decreased after recycling them twice. Considering the changes in various properties of the WPCfs and WPCps, the FFF-printed WPC parts can be reprocessed only once through 3D printing.

Unveiling a novel exopolysaccharide produced by Pseudomonas alcaligenes Med1 isolated from a Chilean hot spring as biotechnological additive

Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermotolerant (growth from 34–44 °C) strain Pseudomonas alcaligenes Med1 from Medano hot spring (39.1 °C surface temperature, pH 7.1) located in the Central Andean Mountains of Chile. Bacterial growth was screened for temperature tolerance (10–60 °C) to confirm the thermotolerance behaviour. Physicochemical properties of the EPS were characterized by different techniques: Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). Whole genome of P. alcaligenes Med1 has also been studied in detail to correlate the structural and functional characteristics with genomic insight. The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps composed of mainly carbon and oxygen. The monosaccharide analysis has shown the presence of glucose, galactose, and mannose sugars at different ratios. TGA revealed the high thermal stability (315.3 °C) of the polysaccharide. The GPC has shown that Med1 is a low molecular weight polysaccharide (34.8 kDa) with low PI. The 2D-NMR linkage analysis suggests a diverse array of glycosidic bonds within the exopolysaccharide structure. The functional properties of the EPS were evaluated for food industry applications, specifically for antioxidant (DPPH, FRAP an H2O2). Extracted Med1 EPS revealed significant emulsification activity against different food grade vegetative oils (Coconut oil, Corn oil, Canola oil, Avocado oil, Sunflower oil, Olive oil, and Sesame oil). The highest 33.9% flocculation activity was observed with 60 mg L−1 EPS concentration. It showed water-holding (WHC) of 107.6% and oil-holding (OHC) capacity of 110.8%. The functional EPS produced by Pseudomonas alcaligenes Med1 from Central Andean Chilean hot spring of central Chile can be a useful additive for the food-processing industry.

Comparison of the Effects of NaOH and Deep Eutectic Solvent Catalyzed Tobacco Stock Lignin Isolation: Chemical Structure and Thermal Characteristics

Uncovering the structure of lignin from biorefinery has an important effect on lignin catalytic depolymerization and the production of bioenergy. In this study, two biorefinery lignins were isolated from tobacco stalks via alkaline and deep eutectic solvent (DES) catalyzed delignification processes, and the lignin heterogeneity structural characteristics were elucidated by gel permeation chromatography, 2D-HSQC, FT-IR, etc., to understand the relationship between the structure and the thermal characteristics of lignin. It was found that the lignins presented various structural characteristics and components, in which the predominant interunit linkages of black liquor lignin are β-O-4 and β-β linkages, and the β-O-4 linkages disappeared by DES treatment. DES lignins exhibited lower molecular weights and yields than black liquor lignin. Thermogravimetric analysis and fixed-bed pyrolysis were also performed to investigate the lignin thermal behavior. The results show that the DES approach can improve the bio-oil production from lignin and highlight the potential of DES lignin as a promising feedstock in the lignin pyrolysis process. This work provides a valuable example of the conversion of biorefinery lignin into pyrolysis products.

An oxidative depolymerized lignin treated by potassium ferrate and its use in preparation of epoxy resin

AbstractLignin, as an industrial by‐product, can be used as a phenolic substancen. In this study, enzymatic hydrolysis lignin (L) was treated with potassium ferrate and phenol respectively to obtain oxidized lignin (OL) and phenolated lignin (PL). Their phenolic hydroxyl content (PhOH) increased by 29.1% and 40.5%, respectively. Then four kinds of epoxy resins were prepared, namely lignin‐free epoxy resin (LFER), L epoxy resin (LER), PL epoxy resin (PLER), and OL epoxy resin (OLER). Gel permeation chromatography (GPC) and Fourier transform infrared analyses indicated that potassium ferrate oxidation could decline the molecular weight (Mw) and increase the PhOH of L. Mechanical properties test and dynamic mechanical analysis (DMA) results show that cured OLER (OLEN) has higher crosslinking density and better mechanical properties (shear strength increased by 14%, tensile strength increased by 15%) than cured LER (LEN). Thermogravimetric analysis results show that OLEN has better thermal stability than cured LFER (LFEN) and LEN. In addition, scanning electron microscopy images showed that the modified L had better compatibility. This study presents a novel approach for lignin oxidation.

A Novel Approach to the Development of Natural Resin‐Based Biopolymer in the Presence of a Reusable Catalyst: Characterization and Modeling of Material Properties

ABSTRACTThe rise in environmental and health concerns has led to increasing attention to nature‐derived materials. Natural resin (NR) is secreted by pine trees, and it is a great monomer source for synthesizing biopolymers. The objective of this study is to produce terpene rosin phenolic resin (TRPR) from NR, turpentine, and phenol by applying a novel polymerization technique. An environmentally friendly and reusable catalyst (Amberlyst15) was chosen instead of traditional ones. TRPR samples were chemically characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC) analysis. The average molecular weight (Mw) of TRPR was detected as 560 g/mol. Artificial neural network (ANN) modeling was designed with three inputs (pressure, temperature, and terpene/NR ratio) and four outputs (reaction yield, acid value, saponification value, and softening point). The highest TRPR yield was obtained with a terpene/NR ratio of (1/2) at 80°C and under 3 atm. The lowest acid and saponification values were calculated as 90.54 and 100.11 mg KOH/g, respectively. The softening point of TRPR reached 80°C and it was suggested for use in the paper, ink, and adhesive industries.