Search Results (114)

Sericin, a silk-derived protein recovered as a by-product of the textile industry, is a renewable biomacromolecule with considerable potential for sustainable material development. Chemical modification represents an effective strategy for its valorization. In this study, acetylation using acetyl chloride (AcCl) was selected as a model reaction to systematically investigate the reactivity of sericin in an N,N-dimethylacetamide/lithium chloride (DMA/LiCl) solvent system and to evaluate the influence of reaction parameters on both the extent of functionalization and protein secondary structure. A Design of Experiments (DoE) strategy, comprising an initial full factorial screening followed by Box–Behnken optimization, was employed to investigate the effects of AcCl equivalents, sericin concentration, and LiCl content. A quantitative FTIR workflow based on constrained Gaussian deconvolution was developed to derive functionalization index (FI) and β-sheet index (BI) from both peak areas and peak intensities, enabling the simultaneous evaluation of chemical modification and structural organization. The exploratory screening identified AcCl as the dominant factor governing sericin functionalization. During the optimization phase, the FI models described the general response trends, whereas the BI was successfully represented by robust quadratic models (R² = 0.977–0.978; adjusted R² = 0.936–0.938), revealing significant linear, interaction, and quadratic effects, with LiCl concentration and sericin concentration playing key roles in governing structural organization. The analytical workflow was verified by reproducibility assessment and independent validation experiments. Overall, this study proposes a quantitative DoE–FTIR framework for systematically investigating sericin functionalization and its associated structural evolution, providing support for future studies aimed at sericin industrial valorization. Full article

Crystal structural stability is one of the core indicators for evaluating the safety of energetic materials, since these energetic materials undergo complex environments during manufacturing, processing, transportation, storage, and application in weapon systems. Energetic cocrystals are a novel solid form of energetic materials with unique crystal structures and novel properties. In this study, the crystal structure stability of hexanitrohexoazaisowurtzitane/1-methyl-3,4,5-trinitro-1H-pyrazole (CL-20/MTNP), an energetic cocrystal with high performance, in a water and organic solvent environment (acetone, N,N-dimethylacetamide, dimethyl sulfoxide and ethanol) is characterized. It was found that CL-20/MTNP partially decomposed and transformed to α-CL-20 both in pure water and a mixture of water and organic solvent, as confirmed by powder X-ray diffraction. The decomposition temperature of CL-20/MTNP and residual solid phase in a chemical environment were observed to be significantly different under thermal stimulation. The degree of the decomposition can be controlled by the temperature and soaking time. Unexpectedly, no significant changes were observed for the decomposition behavior after the introduction of organic solvents. Moreover, a polydopamine coating method was also applied to inhibit the decomposition of the cocrystal structure of CL-20/MTNP. These results are of significant reference value for understanding the crystal structure stability of energetic cocrystals and evaluating their safety in practical applications. Full article

To address the common drawbacks of polyamine-based CO₂ absorbents, such as high viscosity and precipitation at high CO₂ loading, a novel liquid–liquid biphasic absorbent composed of triethylenetetramine (TETA), 1-(2-aminoethyl)piperazine (AEP), N,N-dimethylacetamide (DMAC), and H₂O was developed in this study. By comprehensively evaluating CO₂ saturation loading, phase separation behavior, rheological properties of the CO₂-rich phase, precipitation suppression, and desorption–regeneration performance, the optimal absorbent formulation was identified as 20 wt% TETA + 10 wt% AEP + 40 wt% DMAC + 30 wt% H₂O. The optimized system enabled more than 98% of the CO₂ absorption products to be concentrated in the lower phase, which accounted for only 56% of the total liquid volume. Compared with the AEP-free TETA/DMAC/H₂O system, the optimized AEP-modified absorbent effectively eliminated precipitation and reduced the viscosity of the CO₂-rich phase to 62.3 mPa·s, while also improving the desorption behavior and cyclic stability of the system. In addition, ¹³C NMR analysis suggested that the salting-out effect is the main driving force for phase separation, with ionic products preferentially enriched in the aqueous phase to form the CO₂-rich lower phase. AEP contributes to viscosity reduction, precipitation suppression, and enhanced regeneration by weakening carbamate aggregation through steric hindrance and promoting bicarbonate formation. Full article

Cellulose is a complex polysaccharide that serves as the primary structural component of plant cell walls. It is highly suitable for packaging films due to its inherent and tunable properties, which offer a sustainable alternative to conventional plastics. In this study, cellulose was extracted from vegetable waste (kale and cabbage) and processed into films using LiCl/N,N-dimethylacetamide (DMAc) as the solvent system. The regenerated cellulose films were characterized and compared with a film prepared from commercial microcrystalline cellulose (MCC) using the same procedure. The vegetable-waste films showed a lower degree of crystallinity than the MCC film. SEM micrographs revealed that the vegetable-waste films possessed smooth and uniform surfaces. Furthermore, they demonstrated good transparency, ductility, and thermal stability. Biodegradation tests indicated rapid decomposition of the vegetable-waste films, which fully degraded within 10 weeks, whereas the MCC film required 16 weeks. The cabbage-derived film exhibited a smoother surface and slightly better mechanical properties than the kale-derived film, suggesting that differences in the cellulose source can influence the regeneration process and, consequently, the properties of the resulting films. Overall, this work demonstrates that vegetable waste can be effectively upcycled into eco-friendly, low-cost cellulose films with strong potential for use in various sustainable material applications. Nevertheless, for edible applications, cytotoxicity testing is required to confirm the absence of residual health-risk reagents such as LiCl and DMAc in the resulting films. Full article

The strong adhesion between cathode materials and aluminium (Al) foil substrates presents a significant challenge in the recycling of spent lithium-ion batteries (LiBs). Conventionally, high temperatures and high concentrations of costly organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) are used to enhance ultrasonication-based delamination. In this study, a novel, eco-efficient approach was demonstrated for delaminating cathode materials from Al foil using a low-concentration organic citric-acid-assisted low-power ultrasonic treatment coupled with a gentle, low-power-per-volume mechanical mixing system at room temperature. The separation mechanism was attributed to the structure disruption, possibly swelling, of the polyvinylidene fluoride (PVDF) binder using low-concentration citric acid and the cavitation effects induced by ultrasound. Key parameters influencing the delamination efficiency included the solvent type, temperature, ultrasonic power, and treatment duration. Under optimised conditions, citric acid was used as the sonication reagent, with a process temperature of 20 °C, 60 W ultrasonic power, and 80 min of ultrasonication; a delamination efficiency of approximately 92% was achieved. The recovered cathode materials exhibited low agglomeration, favouring subsequent leaching processes. This work proposes an environmentally friendly and effective method for cathode and Al foil recovery from spent LiBs, integrating manual dismantling, ultrasonic treatment, and material separation. Full article

Currently, only a limited number of Mark–Houwink–Sakurada (MHS) equations are available for chitin, and their applicability is constrained by the narrow range of suitable solvent systems. The Mark–Houwink–Sakurada (MHS) equation is a widely used and practical approach for estimating polymer molecular weight from intrinsic viscosity measurements, particularly when chromatographic techniques are not readily accessible. This study aimed to establish new MHS equations for chitin to facilitate reliable molecular weight determination across different solvents and temperatures. Chitin samples with varying molecular weights were prepared via H₂O₂ degradation, and their weight-average molecular weights (Mw) were determined by high-performance size-exclusion chromatography (HPSEC). Intrinsic viscosity ([η]) was measured using a capillary viscometer at 25 and 30 °C in three solvent systems: 5% LiCl/N,N-dimethylacetamide (LiCl/DMAc), 8% NaOH/4% urea, and 10% NaOH/0.3% tannic acid (w/w). Double-logarithmic plots of Mw versus [η] were constructed to derive the corresponding MHS equations. At identical molecular weights and temperatures, intrinsic viscosity followed the order: LiCl/DMAc > NaOH/urea > NaOH/tannic acid. Increasing temperature led to higher intrinsic viscosity and conformation parameter (a) values. Chitin dissolved in LiCl/DMAc and NaOH/urea exhibited rod-like conformations, with a values ranging from 0.79 to 0.97, whereas chitin in NaOH/tannic acid displayed random coil behavior (a = 0.56–0.69). These established MHS equations expand the solvent applicability for chitin molecular weight determination and provide insights into its solution conformation under different chemical environments. Full article

Owing to their outstanding thermal and mechanical properties, polyimides (PIs), polyamides (PAs), and poly(amide-imides) (PAIs) are essential for developing and manufacturing modern high-tech products, including electroactive ones. Despite their large-scale production for diverse applications, the synthesis of these polymers traditionally relies on highly toxic solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone (NMP), and m-cresol. This work investigates the possibility of replacing these hazardous solvents with a more sustainable and “green” alternative, N-butyl-2-pyrrolidone (NBP). We have thoroughly studied and analyzed the synthesis of various PIs, PAs, and PAIs via one- and two-step polycondensation of tetracarboxylic acid dianhydrides with diamines, low-temperature polycondensation of terephthaloyl chloride with diamines, and low-temperature polycondensation of tetracarboxylic acid dianhydrides and terephthaloyl chloride with diamines, respectively. Our results demonstrate that substituting NBP for NMP presents distinct characteristics and outcomes for each process. By optimizing the reaction conditions, we were able to obtain high-molecular-weight products (M_n = 37–346 kDa; M_w = 133–537 kDa) for all polymer classes studied. Thus, this work establishes NBP as a suitable and promising solvent for synthesizing PIs, PAs, and PAIs with diverse chemical structures and tunable molecular weight characteristics. Full article

Pineapple fibers were used as a sustainable raw material to isolate native cellulose from alkaline–acid treatment. The cellulose fibers were regenerated into transparent and flexible cellulose hydrogels using the lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solvent system, followed by a phase-inversion process of the cellulose solution under ethanol vapor. Chlorhexidine was incorporated into the hydrogels to provide antibacterial properties. The concentration of chlorhexidine ranged from 0.1 to 0.8 wt%. The prepared hydrogels showed better early onset cytocompatibility than the cell culture dish used as a control. For the evaluation of antibacterial properties, strains of Streptococcus mutans, Streptococcus sanguis, and Streptococcus anginosus were used. The results indicated antibacterial activity at all chlorhexidine concentrations tested, with the area of bacterial inhibition increasing with increasing bactericidal content in the hydrogel films. Adding bactericide into cellulose films did not compromise their early onset cytocompatibility in the first 72 h. The study suggests that adding chlorhexidine provides the hydrogel films with antibacterial properties, potentially expanding their applications in dentistry. Full article

The aim of this work was to prepare new heterodimeric molecules containing pharmacophoric fragments of 3-cyanoquinoline/3-aminothieno[2,3-b]pyridine/3-aminothieno[2,3-b]quinoline on one side and phenothiazine on the other. The products were synthesized via selective S-alkylation of readily available 2-thioxo-3-cyanopyridines or -quinolines with N-(chloroacetyl)phenothiazines, followed by base-promoted Thorpe–Ziegler isomerization of the resulting N-[(3-cyanopyridin-2-ylthio)acetyl]phenothiazines. We found that both the S-alkylation and the Thorpe–Ziegler cyclization reactions, when conducted with KOH under heating, were accompanied to a significant extent by a side reaction involving the elimination of phenothiazine. Optimization of the conditions (0–5 °C, anhydrous N,N-dimethylacetamide and NaH or t-BuONa as non-nucleophilic bases) minimized the side reaction and increased the yields of the target heterodimers. The structures of the products were confirmed by IR spectroscopy, ¹H, and ¹³C DEPTQ NMR studies. It was demonstrated that the synthesized 3-aminothieno[2,3-b]pyridines can be acylated with chloroacetyl chloride in hot chloroform. The resulting chloroacetamide derivative reacts with potassium thiocyanate in DMF to form the corresponding 2-iminothiazolidin-4-one; in this process, phenothiazine elimination does not occur, and the Gruner–Gewald rearrangement product was not observed. The structural features and spectral characteristics of the synthesized 2-iminothiazolidin-4-one derivative were investigated by quantum chemical methods at the B3LYP-D4/def2-TZVP level. A range of drug-relevant properties was also evaluated using in silico methods, and ADMET parameters were calculated. A molecular docking study identified a number of potential protein targets for the new heterodimers, indicating the promise of these compounds for the development of novel antitumor agents. Full article

Regenerative endodontic procedures (REPs) are a promising treatment for immature teeth with pulpal necrosis. However, the outcomes remain unpredictable, partly due to scaffold limitations. Beta-glucan (BG), a bioactive polysaccharide with regenerative properties, may enhance scaffold performance. This study aimed to fabricate BG-coated polyvinylpyrrolidone/cellulose acetate (PVP/CA) electrospun scaffolds and evaluate their physicochemical properties and cell attachment. Electrospun scaffolds were fabricated by electrospinning a 10% w/v PVP/CA (70:30) solution in acetone and N,N-dimethylacetamide (2:1) (PC). BG (8% w/v in 1 M NaOH) was electrosprayed onto the scaffold at 0.1, 0.2, and 0.4 mL volumes, generating PC-BG01, PC-BG02, and PC-BG04, respectively. Scaffold characterization included SEM, FTIR, BG enzymatic assay, water absorbance, degradation, and cell adhesion assays. SEM images of the scaffolds exhibited smooth cylindrical fibers (547.3–585.9 nm diameter) with high porosity (42.37–49.91%). BG particles were confirmed by elemental analysis and BG enzymatic assay. At 28 days, the PC group showed significant fiber diameter and porosity reduction. BG particle degradation was observed at 14 and 28 days. Notably, BG-coated scaffolds significantly enhanced initial apical papilla cell adhesion at 1 and 24 h. These findings highlight the potential of BG-coated scaffolds as bioactive scaffolds for REPs. Full article

Despite the emergence of eco-friendly solvents and scalable methods for polymeric membrane fabrication, studies on the impacts of solvent synthesis and manufacturing scale-up have not been conducted. To this end, a life cycle assessment (LCA) was developed with the goal of determining the global environmental and health impacts of producing polysulfone (PSf) membranes with the solvents PolarClean and γ-valerolactone (GVL) via doctor blade extrusion (DBE) and slot die coating (SDC). Along with PolarClean and GVL, dimethylacetamide (DMAc) and N-methyl-2-pyyrolidone (NMP) were included in the LCA as conventional solvents for comparison. The dope solution viscosity had a major influence on the material inventories; to produce a normalized membrane unit on a surface area basis, a larger quantity of PSf-PolarClean-GVL materials was required due to its high viscosity. The life cycle impact assessment found electricity and PolarClean to be major contributing parameters to multiple impact categories during membrane fabrication. The commercial synthesis route of PolarClean selected in this study required hazardous materials derived from petrochemicals, which increased its impact on membrane fabrication. Due to more materials being required to fabricate membranes via SDC to account for tool fluid priming, the PSf-PolarClean-GVL membrane fabricated via SDC exhibited the highest impacts. The amount of electricity and concentration of PolarClean were the most sensitive parameters according to Spearman’s rank coefficient analysis. A scenario analysis in which the regional energy grid was substituted found that using the Swedish grid, which comprises far more renewable technologies than the global and US energy grids, significantly lowered impacts in most categories. Despite the reported eco-friendly benefits of using PolarClean and GVL as alternatives to conventional organic solvents, the results in this study provide a wider perspective of membrane fabrication process impacts, highlighting that upstream impacts can counterbalance the beneficial properties of alternative materials. Full article

Background/Objectives: Airborne viral diseases pose a health risk, due to which there is a growing interest in developing filter materials capable of capturing fine particles containing virions from the air and that also have a virucidal effect. Nanofiber membranes made of poly(vinylidene fluoride) dissolved in N,N-dimethylacetamide and functionalized with copper, silver, and zinc nanoclusters were fabricated via electrospinning. This study aims to evaluate and compare the virucidal effects of nanofibers functionalized with metal nanoclusters against the human influenza A virus A/WSN/1933 (H1N1) and SARS-CoV-2. Methods: A comprehensive characterization of materials, including X-ray diffraction, scanning electron microscopy, microwave plasma atomic emission spectroscopy, thermogravimetric analysis, contact angle measurements, nitrogen sorption analysis, mercury intrusion porosimetry, filtration efficiency, and virucidal tests, was used to understand the interdependence of the materials’ physical characteristics and biological effects, as well as to determine their suitability for application as antiviral materials in air filtration systems. Results: All the filter materials tested demonstrated very high particle filtration efficiency (≥98.0%). The material embedded with copper nanoclusters showed strong virucidal efficacy against the SARS-CoV-2 alpha variant, achieving an approximately 1000-fold reduction in infectious virions within 12 h. The fibrous nanowire polymer functionalized with zinc nanoclusters was the most effective material against the human influenza A virus strain A/WSN/1933 (H1N1). Conclusions: The materials with Cu nanoclusters can be used with high efficiency to passivate and kill the SARS-CoV-2 alpha variant virions, and Zn nanoclusters modified activated porous membranes for killing human influenza A virus A7WSN/1933 (H1N1) virions. Full article

Water electrolysis for hydrogen production has garnered significant attention in the context of increasing global energy demands and the “dual-carbon” strategy. However, practical implementation is hindered by challenges such as high overpotentials, high catalysts costs, and insufficient catalytic activity. In this study, three mono and bimetallic metal−organic framework (MOFs)-derived electrocatalysts, Fe-MOFs, Fe/Co-MOFs, and Fe/Mn-MOFs, were synthesized via a one-step hydrothermal method, using nitro-terephthalic acid (NO₂-BDC) as the ligand and N,N-dimethylacetamide (DMA) as the solvent. Electrochemical tests demonstrated that the Fe/Mn-MOFs catalyst exhibited superior performance, achieving an overpotential of 232.8 mV and a Tafel slope of 59.6 mV·dec⁻¹, alongside the largest electrochemical active surface area (ECSA). In contrast, Fe/Co-MOFs displayed moderate catalytic activity, while Fe-MOFs exhibited the lowest efficiency. Stability tests revealed that Fe/Mn-MOFs retained 92.3% of its initial current density after 50 h of continuous operation, highlighting its excellent durability for the oxygen evolution reaction (OER). These findings emphasize the enhanced catalytic performance of bimetallic MOFs compared to monometallic counterparts and provide valuable insights for the development of high-efficiency MOF-based electrocatalysts for sustainable hydrogen production. Full article

Polyimides (PIs) are materials that are resistant to high temperatures and crucial for the manufacturing of films, fibers, coatings, and 3D-printed items. PIs are widely used as electrically insulating materials in electronics and electrical engineering. This study investigated how the chemical structure (i.e., choice of initial monomers), the synthesis conditions of the prepolymer (i.e., choice of amide solvent), and the conditions for forming polyimide films (i.e., final curing temperature) affect the thermophysical properties and short-term electrical strength of obtained polyimide films of different chemical structures. In this work, we varied the compositions of the dianhydrides used for synthesizing polyamic acids—pyromellitic acid (PMDA), tetracarboxylic acid diphenyl oxide (ODPA) and 1,3-bis(3′,4-dicarboxyphenoxy)benzene acid (R)—with a constant diamine: 4,4′-oxydianiline (ODA). Additionally, we varied the amide solvents employed: N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP). This study represents the first investigation into how the choice of solvent in the synthesis of thermoplastic polyimide prepolymers affects their short-term electrical strength. The molecular weights of the polyamic acids were determined using gel permeation chromatography (GPC). The deformation and strength characteristics of the investigated films were also assessed. The thermophysical properties of the polyimides were evaluated via dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). X-ray diffraction analysis and infrared spectroscopy (IR) were conducted on the examined film samples. The short-term electrical strength was also evaluated. Full article

This project intends to develop restorative dental nanomaterial composites that are light-curable and show minimal shrinkage. Such nanocomposites are improved via employing 2,2-bis[4(2-hydroxy-3-methacryloylpropyloxy) phenyl] propane (Bis-GMA) with the unsaturated monomers bisphenol A dimethacrylate, N,N-dimethylacetamide (DMA), ethylene glycol (EG), and methacrylic acid (MAA) and loading them with SiO₂, ZrO₂, or hydroxyapatite (HA) as nanofillers of 10–30 nm. The first step was to create and characterize these novel dental materials. 1,6-hexanediol methacrylate (HDOMA) was used as a cross-linking agent. The composites based on Bis-GMA and HDOMA with a mass ratio of 40/20 were loaded with 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 wt.% of the fillers mentioned above. Photopolymerization was induced by a system of photoinitiation based on Camphorquinone/2- (Diethyl amino) ethyl acrylate (CQ/DMAEMA). The nanofillers were treated with 3-(methacryloyloxy) propyltrimethoxysilane (MPTMS) at a ratio of 1.5, 2.5, as well as 3.5%wt. compared to the filler) and a silane coupling agent to increase bonding between the phases and reduce the tendency of agglomerations. SEM images displayed the adhesion between the matrix and the three functionalized nanofillers. FTIR was used to prove the functionalization of the nanofillers by silanization with MPTMS. According to the polymer matrix, two different series of dental nanocomposites were obtained. The compressive strength of dental nanocomposites treated with 2.5 wt.% MPTMS was considerably more significant than those treated with 1.5 and 3.5%wt. MPTMS. Compressive strength (CS) and volumetric shrinkage (VS) were examined as examples of physicochemical properties. This improved nanocomposite was tested for its suitability as a dental restorative material and found to have low shrinkage and high strength. Full article