Differential Scanning Calorimetry Research Articles

On the Stabilizing Effect of Aspartate and Glutamate and Its Counteraction by Common Denaturants.

By performing differential scanning calorimetry(DSC) measurements on RNase A, we studied the stabilization provided by the addition of potassium aspartate(KAsp) or potassium glutamate (KGlu) and found that it leads to a significant increase in the denaturation temperature of the protein. The stabilization proves to be mainly entropic in origin. A counteraction of the stabilization provided by KAsp or KGlu is obtained by adding common denaturants such as urea, guanidinium chloride, or guanidinium thiocyanate. A rationalization of the experimental data is devised on the basis of a theoretical approach developed by one of the authors. The main contribution to the conformational stability of globular proteins comes from the gain in translational entropy of water and co-solute ions and/or molecules for the decrease in solvent-excluded volume associated with polypeptide folding (i.e., there is a large decrease in solvent-accessible surface area). The magnitude of this entropic contribution increases with the number density and volume packing density of the solution. The two destabilizing contributions come from the conformational entropy of the chain, which should not depend significantly on the presence of co-solutes, and from the direct energetic interactions between co-solutes and the protein surface in both the native and denatured states. It is the magnitude of the latter that discriminates between stabilizing and destabilizing agents.

Exploring the Dissolution, Solid-state Properties, and Long-term Storage Stability of Cryoprotectant-free Fenbendazole Nanoparticles.

Fenbendazole is an antiparasitic drug widely used in veterinary medicine to treat parasitic infections caused in animals like cattle, horses, sheep, and dogs. Recently, it has been repositioned as a potential alternative for cancer treatment. However, it is a highly hydrophobic molecule (0.9 ug/mL), which can compromise its dissolution rate and absorption. Thus, this work aimed to apply a nanotechnological approach to improve drug solubility and dissolution performance. Fenbendazole nanoparticles stabilized by different poloxamers were obtained by lyophilization without cryoprotectants. The behavior of the drug in the solid state was analyzed by X-ray diffractometry, differential scanning calorimetry, and infrared spectroscopy. The nanosystems were also evaluated for solubility and dissolution rate. A long-term stability evaluation was performed for three years at room temperature. The yields of the lyophilization ranged between 75 and 81% for each lot. The nanoparticles showed a submicron size (< 340 nm) and a low polydispersity depending on the stabilizer. The physicochemical properties of the prepared systems indicated a remarkable amorphization of the drug, which influenced its solubility and dissolution performance. The drug dissolution from both the fresh and aged nanosystems was significantly higher than that of the raw drug. In particular, nanoparticles prepared with poloxamer 407 showed no significant modifications in their particle size in three years of storage. Physical stability studies indicated that the obtained systems prepared with P188, P237, and P407 suffered certain recrystallization during long storage at 25 °C. These findings confirm that selected poloxamers exhibited an important effect in formulating fenbendazole nanosystems with improved dissolution.

Development of a Stable Lyophilized Cyclophosphamide Monohydrate Formulation Using Non-Aqueous Solvents.

To ensure product stability, it is critical to maintain the monohydrate state of cyclophosphamide following lyophilization, as this is the most stable solid form of the Cyclophosphamide. On the other hand, because of their limited aqueous solubility and stability, non-aqueous solvents are preferred for determining the composition and stability of bulk solutions. Hence, the purpose of this study was to use non-aqueous solvents for determining the composition and stability of bulk solutions, and to shorten the lyophilization process by retaining the cyclophosphamide monohydrate. Furthermore, prior to selecting the solvent for the bulk solution consisting of 90:10 tertiary butyl alcohol (TBA) and acetonitrile (ACN), various factors were taken into account, including the freezing point, vapor pressure of solvents, solubility, and stability of cyclophosphamide monohydrate. The concentration of the bulk solution was adjusted to 200mg/mL in order to optimize the fill volume, enhance sublimation rates at lower temperatures during primary drying, and eliminate the need for secondary drying. The differential scanning calorimetry (DSC) measurements of bulk solution were used to improve the lyophilization cycle. The lyophilization cycle opted was freezing at a temperature of -55°C with annealing step at -22°C by which the reconstitution time was significantly reduced. The drying was performed at below - 25°C while maintaining a chamber pressure of 300 mTorr. The complete removal of non-aqueous solvents was achieved by retaining water within the system. The presence of cyclophosphamide monohydrate was confirmed using X-ray diffraction (XRD). The reduction of lyophilization process time was established by conducting mass transfer tests and evaluating the physicochemical properties of the pharmaceutical product. Using non-aqueous solvents for freeze-drying cyclophosphamide is a viable option, and this study provides significant knowledge for the advancement of future generic pharmaceuticals.

Experimental Exploration of Cellulose Material for Battery Separators and Artificial Neural Network-Driven Predictive Modeling for Enhanced Thermal Safety in Electric Vehicles

Abstract Lithium-ion batteries (LIBs) are the most reliable energy storage devices nowadays because of their high energy density, long life cycle, and low self-discharge rate. But still, the safety concern is a significant problem in the area. When talking about LIB safety, thermal effects come first; this leads to thermal runaway, fires, and explosions. The critical component of LIB that has a great role in safety is the separator, which serves the purpose of preventing direct contact between the positive and negative electrodes while enabling the movement of lithium ions. This work aimed to find naturally available cellulose material for the LIB separator and to predict the performance of the material by artificial neural network (ANN) for better control of thermal problems that happen with traditional polymer separator materials. The cellulose derived from banana peels is isolated and characterized for its potential use as a separator material. The study conducts the four selected characterization approaches, scanning electronics microscopy (SEM) with three different resolutions to assess the morphology of the extracted cellulose, differential scanning calorimetry (DSC) to measure the heat flow with temperature change on the cellulose and the value obtained 231.22 J/g at a maximum temperature of 323.18 °C, thermogravimetric analysis (TGA) was used to examine the weight loss of the cellulose with respect to temperature variation, which results in a weight loss of 59.37% when the temperature reaches 235 °C, which is considered favorable, and a differential thermal analysis (DTA) was used to know the temperature difference in the banana peel cellulose (BPC), which results in a temperature of 330.23 °C. This morphological and thermal analysis technique for the BPC is used to determine the heat-related properties of the BPC, including phase transitions, thermal stability, and reaction. In addition, these results show BPC as an alternative material for separators in comparison to the existing polymer-based materials. Furthermore, these experimental results are used to train an ANN to predict the performance of BPC material using a binary classification. Because of the training process, 97.58% accuracy was achieved.

Binary nanoconjugation of zein–methylcellulose for improving curcumin properties: solubility, controlled release and anticancer activity

AbstractFor cancer treatment, a novel nanocarrier has been developed, utilizing natural compounds. Zein protein (Z) and methylcellulose (MC) polysaccharide were formulated as a nanocarrier for nutraceutical curcumin (Cur). The zein–methylcellulose nanoconjugate (ZMC) appeared spherical/monodispersed in transmission electron microscopy images. Hydrodynamic sizes were 164 ± 20.2 and 190 ± 28.2 nm for ZMC and ZMC@Cur, respectively. For both formulations, zeta potential, differential scanning calorimetry, Fourier transform infrared spectroscopy and X‐ray diffraction analyses were conducted. Curcumin encapsulation efficiency was 92%, and its release profile was pH responsive. Using MTT assay, ZMC@Cur demonstrated a significant cytotoxic effect against MCF‐7 and HepG2, surpassing the impact of curcumin. This underscores the pivotal role of ZMC@Cur in enhancing curcumin properties, thereby potentiating cancer cell death. Compared with free curcumin, ZMC@Cur markedly promoted DNA damage in cancer cells, owing to precise curcumin targeting into the nucleus. Accordingly, the proposed bionanocomposite stands as an efficient vehicle for curcumin, showcasing its crucial role in combating cancer via improving the pharmaceutical properties of curcumin. © 2024 Society of Chemical Industry.

Mechanochemical comparison of ball milling processes for levofloxacin amorphous polymeric systems

This study aimed to investigate the amorphization capabilities of levofloxacin hemihydrate (LVXh), a fluoroquinolone drug, using a polymer excipient, Eudragit® L100 (EL100). Ball milling (BMing) was chosen as the manufacturing process and multiple mill types were utilized for comparison purposes. The product outcomes of each mill were analyzed in detail. The solid-state of the samples produced was comprehensively characterized by Powder X-ray Diffraction (PXRD), In-situ PXRD, Differential Scanning Calorimetry (DSC), Solid-State Fourier Transform Infrared Spectroscopy (FT-IR), and Dynamic Vapor Sorption (DVS). The crystallographic planes of LVXh were investigated by in-situ PXRD to disclose the presence or absence of weak crystallographic plane(s). The mechanism of LVXh:EL100 system formation was discovered as a two-step process, first involving amorphization of LVXh followed by an interaction with EL100, rather than as an instantaneous process. DVS studies of LVXh:EL100 samples showed different stability properties depending on the mill used and % LVXh present. Overall, a more sustainable approach for achieving full amorphization of the fluoroquinolone drug, LVXh, was accomplished, and advancements to the fast-growing world of pharmaceutical mechano- and tribo-chemistry were made.

Prolonged release from lipid nanoemulsions by modification of drug lipophilicity

In addition to the solubilization of poorly water-soluble, highly lipophilic drugs, lipid nanoemulsions bear potential for drug targeting approaches. This requires that the drug remains within the emulsion droplets until they reach the site of action. Since drug release is rather controlled by the lipophilicity of the drug than by the formulation, this study systematically investigated the influence of drug lipophilicity on the course of drug transfer in (physiological) acceptor media. An increase in drug lipophilicity, according to ClogD/P values, was achieved by the formation of lipophilic prodrugs of 5-phenylanthranilic acid – a potential pathoblocker. The range of substances was supplemented by orlistat, lumefantrine and cholesteryl acetate as model drugs. Drug transfer from supercooled trimyristin nanodroplets was determined via differential scanning calorimetry by monitoring their onset crystallization temperature, which decreases linearly with increasing drug content. Release of the model (pro)drugs ranged from burst to hardly any release in the order of the ClogD/P values. Except for cholesteryl acetate, the results were in line with the lipophilicity of the model (pro)drugs estimated by their retention times on a reversed-phase HPLC column under isocratic conditions. An approximate prediction of drug release kinetics was, thus, possible by logP calculations and, to a limited extent, also by reversed-phase HPLC. A further finding was the increased drug loading capacity of the lipid nanoemulsion for lipophilic prodrugs, if the structural changes of the parent compound were accompanied by a lower melting point.

Research on ultrasonic-stationary shoulder assisted friction stir lap welding of thermoplastic polymer and aluminum alloy

Friction stir lap welding (FSLW) has advantages on obtaining dissimilar upper polymer and lower aluminum materials joint (polymer/Al joint), and how to heighten the bearing capacity of polymer/Al joint as much as possible is greatly meaningful for the manufacturing industries. In this study, choosing dissimilar polyamide 6 (PA 6) polymer and 6061-T6 aluminum alloy materials as research object, traditional FSLW, stationary shoulder assisted FSLW (SSFSLW) and ultrasonic-stationary shoulder assisted FSLW (U-SSFSLW) processes were compared to understand the mechanism of ultrasonic enhancement on the polymer/Al joint. Firstly, the surface morphologies were studied. Then the analyses of micro/macro-structures, mechanical properties and fracture features were carried out by optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and tensile tests. Results showed that the lap shear failure load of polymer/Al joint by U-SSFSLW reached 1502 N from 814 N by traditional FSLW, because the addition of ultrasonic avoided the bulged-nodule structures on top surface and the cavity defect in stir zone (SZ), broke the Al anchor in upper plate, enlarge the width of SZ in lower plate, and made the deeper micro-pits and larger dents at the interface between SZ bottom and lower plate. The U-SSFSLW process provides an effective way to fabricate the high-strength hybrid joint of dissimilar upper polymer and lower Al materials.

The Specificity of Determining the Latent Heat of Solidification of Cast Hypoeutectic AlSiCu Alloys Using the DSC Method.

Latent heat is commonly measured using Differential Thermal Analysis (DTA) or Differential Scanning Calorimetry (DSC) or calculated using software packages (Thermo-Calc). In this study, the DSC method was used to comprehensively evaluate the accuracy of calculated latent heat for a specific range of cast AlSiCu alloys, considering their solidification under different cooling conditions. The tests involved varying concentrations of two crucial alloying elements: wSi (5, 7, and 9%) and wCu (1, 2, and 4%). All selected alloys were analyzed under three distinct cooling/heating rates: 6, 10, and 50 °C/min. The Thermo-Calc method was used in this work to calculate the latent heats of the investigated alloys. The results obtained show good agreement between the measured and calculated values. The increase in silicon content in the investigated alloys from 4.85% to 9.85% resulted in the increase in latent heat from 407.6 kJ/kg to 467.5 kJ/kg. Higher cooling rates, such as 50 °C/min, resulted in a reduced latent heat release compared to slower rates such as 10 °C/min and 6 °C/min.

Development of Thyme-Infused Polydimethylsiloxane Composites for Enhanced Antibacterial Wound Dressings.

Polydimethylsiloxane (PDMS) is widely used in biomedical applications due to its biocompatibility and flexibility but faces challenges due to its hydrophobicity and limited mechanical strength. This study explores the incorporation of thyme (Thymus vulgaris L.) into PDMS to enhance its properties for wound dressing applications. PDMS composites containing 2.5 wt.% and 5 wt.% of thyme were prepared and evaluated for physical, chemical, mechanical, and biological properties. Scanning electron microscopy, contact angle measurements, absorption tests, Fourier-transform infrared spectroscopy, differential scanning calorimetry, hardness, tensile testing, antibacterial activity, and cell viability assays were conducted. Thyme integration improved mechanical properties with increased absorption and preserved hydrophobicity. FTIR and DSC analyses indicated minimally altered crystallinity and chemical interactions. Hardness decreased with higher thyme content due to terpene-induced polymerization inhibition. Tensile testing showed reduced stress at break but increased elongation, suitable for wound dressings. Enhanced antibacterial activity was observed, with composites meeting bacteriostatic standards. Cell viability exceeded 70%, with optimal results at 2.5 wt.% thyme, attributed to cytokine-inducing compounds. Thyme-incorporated PDMS composites exhibit improved antibacterial and mechanical properties, demonstrating the potential for advanced wound dressings.

DNA interaction of selected tetrahydropyrimidine and its effects against CCl4-induced hepatotoxicity in vivo: Part II.

Tetrahydropyrimidine (compound A = methyl 4-[4'-(heptyloxy)-3'-methoxyphenyl]-1,6-dimethyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate) was chosen for in vivo studies after exhibiting noteworthy in vitro activity against the K562 and MDA-MB-231 cell lines, with IC50 values of 9.20 ± 0.14 µM and 12.76 ± 1.93 µM, respectively. According to experimental (fluorescence titration, viscosity, and differential scanning calorimetry) results, A interacts with DNA via the minor groove. In vivo, acute oral toxicity studies in Wistar albino rats proved no noticeable symptoms of either toxicity or death during the follow-up period. Genotoxic and antigenotoxic studies at three different concentrations of A (5, 10, and 20 mg/kg of body weight) in Wistar albino rats showed that the dose of 5 mg/kg body weight did not cause DNA damage and had a remarkable DNA protective activity against CCl4-induced DNA damage, with a percentage reduction of 78.7%. It is also important to note that, under the investigated concentrations of A, liver damage is not observed. Considering all experimental outcomes realized under various in vivo investigations (acute oral toxicity, genotoxicity, antigenotoxicity, and biochemical tests), compound A could be a promising candidate for further clinical testing.

Structure-Glass Transition Relationships in Non-Isocyanate Polyhydroxyurethanes.

The molecular dynamics, with an emphasis on the calorimetric and dynamic glass transitions, of non-isocyanate polyhydroxyurethanes (PHUs) produced by the equimolar polyaddition of polyether-based dicyclic carbonates (P-CCs) and various short diamines was studied. The diamine component consisted of a short aliphatic diamine (1,4-diaminobutane, DAB) and a more complex 'characteristic' diamine. The study was conducted to investigate (i) the chemical structure of the characteristic amine, (ii) its molar ratio, and (iii) the structure and molar mass of the P-CC. Infrared spectroscopy, differential scanning calorimetry, and broadband dielectric spectroscopy were employed. The P-CC, constituting the bulk of the systems, was the most crucial component for the glass transition. The characteristic amine influenced the glass transition as a result of its bulky structure, but also presumably as a result of the introduction of free volume and the formation of hydrogen bonds. The dynamic glass transition (α relaxation) trace in the Arrhenius plots showed a subtle change at a certain temperature that merits further study in the future. The charge mobility was fully coupled with the molecular mobility, as evidenced by dc conductivity being directly proportional to the characteristic frequency of α relaxation. The fluctuation in carbonyl units (β relaxation) was mildly affected by changes in their immediate environment.

Influence of distal-end heat treatment in the properties of heat-activated NiTi archwires.

The aim of this study was to evaluate the extent of property changes caused by heating the distal portion of heat-activated nickel-titanium (NiTi) wires. Forty preformed heat-activated NiTi archwires (3MUnitek, Monrovia, CA, USA) with anominal cross-section of 0.018″ were used in this study. The archwires were divided into acontrol group, not submitted to heat treatment and, thus, maintaining the as-received properties, and an experimental group, in which the archwires were submitted to heat treatment for distal bending at one end. Wire segments of control and experimental groups were submitted to differential scanning calorimetry (DSC) and Vickers microhardness measurements. The DSC results suggest local recrystallization and precipitate dissolution at the heat-treated tip, which decreases as the distance to the wire's tip increases. Vickers microhardness tests revealed significant changes for distances between 6and 8 mm from the wire's tip. Heating the distal portion of heat-activated NiTi archwires should be performed with care since this clinical procedure may compromise the performance of these wires to a distance of 8 mm from the archwire end. Heat treatment for distal bending in heat-activated NiTi archwires may be performed, with little impact on the areas adjacent to heat treatment. In cases presenting molars requiring significant orthodontic corrections, it should be preferred to apply other techniques to avoid archwire sliding, such as crimpable stops, or to have flame control to avoid placing aheat-treated section in the tubes of these molars.

Ice crystals and oxidative stress affect the viability of Areca catechu seeds following cryopreservation

This study aimed to examine the effects of ice crystals and oxidative stress on seed viability in the context of cryopreservation, with the ultimate goal of identifying potential solutions to address the persistently low regeneration rate observed in recalcitrant medicinal plant seeds following cryopreservation. Using differential scanning calorimetry technology alongside seeds germination at different moisture levels after cryopreservation helped determine the best moisture content and freezing process for Areca catechu seeds. Seeds with 17–21 % moisture content and treated with PVS2 vitrification solution showed higher survival rates after cryopreservation. The oxidative markers of A. catechu seed embryos exhibited alterations due to vitrification freezing. However, there was no substantial association between seed viability and oxidative markers, such as reactive oxygen species (ROS), suggesting that oxidative damage mediated by ROS is not the primary factor contributing to the diminished viability of A. catechu seeds following cryopreservation. The inclusion of vitamin E, reduced glutathione (GSH), and 2-nitrobenzoic acid in the vitrification cryoprotectant achieved some improvement in seed viability of approximately 10 times, with GSH exhibiting the most pronounced optimizing effect.

Solid State Additive Manufacturing of Thermoset Composites.

Softening and subsequent deformation are significant challenges in additive manufacturing of thermal-curable thermosets. This study proposes an approach to address these issues, involving the preparation of thermosetting composite powders with distinct curing temperatures, the utilization of cold spray additive manufacturing (CSAM) for sample fabrication, and the implementation of stepwise curing for each component. To validate the feasibility of this approach, two single-component thermosetting powders P1 and P2 and their composite powder C were subjected to CSAM and stepwise curing. From the sample morphology observation and deposition/curing mechanism investigation based on thermomechanical analysis and differential scanning calorimetry, it is found that severe plastic deformation occurs during the CSAM process, accompanied by heat generation, leading to local melting to promote a good bond at the contact surface of the particles and form small pores. During the progressive curing, the samples printed using C demonstrate superior deformation resistance compared with those using P1 and P2, and the curing time is reduced from 16.7 h to 1.5 h, due to the sequential curing reactions of P1 and P2 components in composite C, allowing the uncured P2 and cured P1 to alternately remain solid for providing structural support and minimizing deformation.

The influence of oxidative aging and wax structure on bitumen physical hardening: Insights from model wax compounds

Physical hardening (PH) significantly affects bitumen's low-temperature performance. This paper investigates the effect of oxidative aging and wax structure on PH using 4-mm dynamic shear rheometer (4-mm DSR) and differential scanning calorimetry (DSC) tests. The results show that the wax chain length has a pronounced effect on the PH. Short-chain waxes, such as C18 and C24 affect the PH while longer-chain n-paraffins like C40 or Sasobit have almost no effect. In addition, the physical hardening index (PHI) is not linearly increasing with wax content but shows a maximum at a particular wax percentage. Wax-doped samples that crystallize before reaching the hardening temperatures typically show a reduced PHI compared to those with crystallization temperatures just below the hardening temperature. When crystallization and melting temperatures are not close to the hardening temperatures, the PHIs are typically reduced. Oxidative aging also influenced the PHI and in most cases the hardening decreased after aging. The highest PHI of almost all investigated samples occurs at 0 °C among the four typical temperatures. This investigation provides insights in the mechanism of PH and in the relations between wax contents, the hardening temperature, and the PHI. It also shows that while long-chain waxes used as warm mix additives, will not cause a PH risk, short-chain waxes present in pyrolyzed waste plastic, for example, should be handled with care. In addition, PH is also crucial for the intermediate service temperatures and not exclusively for thermal cracking at low temperatures.

Reinforced facilitated transport PEBA membrane by 2D Fe-doped TiO2 macroporous nanosheets for CO2 separation: Utilizing cationic and non-ionic surfactants

In this study, macroporous nanosheets of 2D Fe-Doped TiO2 were synthesized, and subsequently, membranes composed of polyether block amide (PEBA) were prepared. These membranes were incorporated with the nanosheets mentioned above, as well as two distinct types of surfactant. The structure and gas separation properties of the membranes were studied using different methods, including atomic force microscopy (AFM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), as well as gas permeation analyses and tensile test. The findings indicated that the nanosheets underwent a porous transformation following the doping process. This occurrence improved the bonding between the nanosheets and PEBA chains, consequently boosting the mechanical strength of the membranes embedded with these nanosheets. Incorporating these nanosheets into the membrane (4 wt%) established a more efficient facilitated transport mechanism via Lewis acid centers, resulting in a 12.5 % increase in CO2 permeability and a 136 % rise in the selectivity of CO2/N2 compared to the pure PEBA membrane. Two different surfactants were introduced to the PEBA/FeTiO2 matrix, resulting in varying impacts on membrane structure and performance. The Cetyl trimethyl ammonium bromide (CTAB) as a cationic surfactant led to membrane stiffening and a significant 241 % enhancement in CO2/N2 selectivity at 1 wt%. On the other hand, the Polysorbat (Tween) as a non-ionic surfactant softened the membrane and boosted CO2 permeability by 53 % at 6 wt% compared to the pure membrane.

Development and optimization of thyme-pennyroyal essential oils based active nanostructured lipid carrier (NLC) containing saffron extract with antioxidant and antimicrobial properties

The saffron extract-loaded nanostructured lipid carrier (NLC) was synthesized by the double emulsion (W/O/W) method for application as a preservative to increase the oxidative and microbial stability of French dressing. The optimization of the NLC system was carried out using a combined D-optimal design methodology and effect of thyme (TEOs)/pennyroyal (PEOs) essential oils, and polyglycerol ester (PGE)/polyglycerol polyricinolate (PGPR) surfactants ratios (independent variables) were investigated on the mean particle size, polydispersity, zeta potential, and encapsulation efficacy (dependent variables). The optimal formulation (NLC opt) was obtained as 90/10 thyme/pennyroyal essential oils and 90/10 polyglycerol esters/polyglycerol polyricinoleate ratio, which resulted in the lowest PDI and particle size (0.38 and 66.87 nm respectively), highest zeta potential and encapsulation efficiency (−26.7 mV and %78.88 respectively). Different techniques including transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analysis were used for the characterization of structure and physicochemical properties of the different NLC systems and confirmed successful incorporation of SE into NLC. The DPPH test showed decrement of antioxidant activity during 30 days of storage and IC50 value was lower in the SE-NLC (0.68 mg/ml) than in the free extract. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests against S. aureus, E. coli, and P. aeruginosa indicated that the SE did not have antibacterial properties. However, NLC formulations showed antimicrobial effect due to the presence of TEOs and PEOs essential oils. Peroxide value of control sample was the highest (8/35 O2/kg) and it was the lowest (3.75 O2/kg) in French dressing with SE-NLC.

Combining linear and cyclic sulfones as a strategy for elaborating more efficient high-dielectric polymer materials: A second case of dipolar glass copolymers

Motivated by the excellent features exhibited by sulfone functional groups in the development of high-dielectric polymer materials, this work assesses the combination of linear and cyclic sulfone structures through copolymerization to prepare novel polymer materials exhibiting high dielectric constants (ԑr'), low dissipative behavior, and improved thermal properties. Five new polymethacrylate-based copolymers with varying compositions were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization. The correct structure and macromolecular nature of the devised materials were confirmed by infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H/13C NMR), and gel permeation chromatography (GPC), while their thermal properties were evaluated using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). All specimens exhibited adequate thermal properties for most capacitor applications in terms of onset degradation (Ti) and glass transition (Tg) temperatures. All materials degraded well above 250 °C, with increased Ti and Tg values depending on the final composition of the cyclic sulfone monomer in the material. The incorporation of cyclic sulfones not only increased the thermal robustness of the specimens but also raised their Tg values to as high as 189 °C, notably expanding the range of temperatures where these systems can operate without dissipative phenomena. More importantly, broadband dielectric spectroscopy (BDS) revealed that all samples exhibited dielectric properties notably superior to those of conventional polymer materials, with high ԑr' values between 6.0 and 8.9 (at 25 °C and 1 Hz) and low loss factors (Tan(δ) < 0.018). Overall, the present work successfully demonstrates the advantages of including cyclic structures with high dipole moments in polymeric backbones, offering a new strategy to enhance the thermal and dielectric properties of high-dielectric polymer materials.

Enabling room temperature solid-state lithium batteries by blends of copolymers and ionic liquid electrolytes

High lithium-concentration phosphonium ionic liquids electrolytes have shown outstanding properties even overcoming ammonium derivatives in terms of viscosity and transport properties. Consequently, they have been also combined with fluorinated polymers, such as poly(vinylidene fluoride) (PVDF) or poly(ionic liquids), for solid-state batteries with satisfying performance at 50 °C. The aim of this work is to develop highly lithium conducting solid-state electrolyte (≥0.1 mS cm−1) at room temperature but maintaining solid-state properties. For this, polymer electrolytes based on ISOBAM alternating copolymer (isobutylene and maleic anhydride) and ionic liquid (P111i4FSI) were developed. The composition-dependent behavior of the solid electrolytes was studied in terms of electrochemical impedance spectroscopy (EIS), reaching σLi+ of 0.52 mS cm−1; differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) under different ionic liquid electrolyte loadings and salt concentration. The polymer electrolytes presented a solid-like behavior in the range of 25 to 90 °C with a storage modulus of 2.3·104 Pa. Finally, the best free-standing membrane electrolytes were tested and compared electrochemically in lithium symmetrical cells and lithium iron phosphate full cells exhibiting an excellent cycling at room temperature.