Varying Chain Length Research Articles

Thermoelectrochemical Method for Quantification of the Micellization Entropy of Redox-Active Polymers.

Redox-active micelles undergo reversible association and dissociation in response to their redox potential and are promising materials for various applications, such as drug delivery and bioimaging. Evaluation of the micellization entropy is critical in controlling the thermodynamics of micelle formation. However, conventional methods such as isothermal titration calorimetry and surface tensiometry require a long measurement time to observe changes in the heat flow or the surface tension caused by the micellization. Here we report a thermoelectrochemical method to quantify the entropy change produced by redox-active micelles. A set of poly(ethyl glycidyl ether-b-ethylene oxide)phenothiazine (PT-EGE-EO) with varied chain length were synthesized, and their micellization entropy was calculated from the temperature-dependent changes of the equilibrium potential. This thermoelectrochemical method enables a quick evaluation of the micellization entropy with only a single sample preparation and temperature sweep. The obtained results showed a reasonable agreement with the conventional surface tensiometry and isothermal titration calorimetry, indicating that the thermoelectrochemical method is a promising alternative for quantification of the micellization entropy.

Impact of the hydrophilic-lipophilic balance of free-base and Zn(II) tricationic pyridiniumporphyrins and irradiation wavelength in PDT against the melanoma cell lines.

The amphiphilic and asymmetric structure of porphyrins, when used as photosensitizers (PSs) for photodynamic therapy (PDT), has been shown through numerous previous studies to be a very important property that facilitates their entry into cells, which improves their efficiency in PDT. In this work, two groups of cationic AB3 pyridiniumporphyrins, free-base and chelated with Zn(II), both substituted with alkyl chains of various lengths, were studied in PDT on melanoma cell lines. The aim was to investigate the impact of hydrophilic-lipophilic balance and Zn(II) chelation, and the importance of matching the irradiation wavelength to the optical properties of the PS on in vitro PDT efficiency. Therefore, spectroscopic studies, singlet oxygen production and lipophilicity as well as cellular uptake, localization and cytotoxicity studies of the two series of porphyrins were performed. In both series of porphyrins, the longest alkyl chain (17C-atoms long) enables the greatest internalization of the PS. Chelation with Zn(II) resulted in better physicochemical properties, but slower cellular internalization. As expected, free-base porphyrins were more PDT efficient than their Zn(II) complexes after 30-min photoactivation by low-fluence (2mW/cm2) red light (643nm). However the use of orange light (606nm) with the same fluence rate was more suitable for Zn(II) porphyrins and resulted in similar overall toxicity to their free-base analogues with similar lipophilicity. Although the highest phototoxicity was achieved with the PSs carrying the longest alkyl chain, TMPyP3-C13H27 and Zn(II)-TMPyP3-C13H27 proved to be the most promising candidates for use in PDT as they exhibit high phototoxicity, but also greater selectivity towards melanoma cell lines (MeWo and A375) compared to fibroblasts (HDF).

Size-controlled antimicrobial peptide drug delivery vehicles through complex coacervation.

Due to the escalating threat of the pathogens' capability of quick adaptation to antibiotics, finding new alternatives is crucial. Although antimicrobial peptides (AMPs) are highly potent and effective, their therapeutic use is limited' as they are prone to enzymatic degradation, are cytotoxic and have low retention. To overcome these challenges, we investigate the complexation of the cationic AMP colistin with diblock copolymers poly(ethylene oxide)-b-poly(methacrylic acid) (PEO-b-PMAA) forming colistin-complex coacervate core micelles (colistin-C3Ms). We present long-term stable kinetically controlled colistin-C3Ms that can be prepared from several block lengths of PEO-b-PMAA polymers, where the polymerisation degree governs the overall micellar size. To achieve precise control over size and polydispersity, which are crucial for drug delivery applications, we investigate the hybridisation of PEO-b-PMAA polymers with varying chain lengths or PMAA homopolymers in ternary complex coacervation systems with colistin. This results in size-tunable colistin-C3Ms, ranging, depending on the mixing ratios, from micellar sizes of 26 nm to 100 nm. With size tunability at rather narrow size distributions and high stability, ternary colistin-C3Ms offer potential advancements in C3M drug delivery, paving the way for more effective and targeted treatments for bacterial infections in precision medicine.

The Influence of the Acyl Side Chain on Pyrene Excimer Formation as a Model for Asphaltene Aggregation

Asphaltene aggregation mechanism is still a nebulous and controversial issue. Many authors argue that the aggregation of its components is due to p-stacking interactions, nonetheless, alkyl chains, heteroatoms, and even acidic groups are also constituents of asphaltenes and can play an important role in the chemistry of asphaltene. Excimers from pyrene are easily detected by fluorescence and were used in the current study to probe the effect of the side chain on the p-stacking capacity of pyrene. Pyrene was acylated with acyl chains varying from two to twelve carbon atoms, and the effect of the variation of the acyl chain length on excimer formation was followed by fluorescence emission spectroscopy. The results revealed that as the side chain grows from two to twelve carbon atoms the excimer/monomer ratio decreases and the excimer heat of formation drops from DH = -6.00 to -1.29 kcal mol-1. Further, the crystal structure of octanoyl pyrene (PC8) indicates that in the crystal structure, the aromatic moiety faces the acyl chain. This result was corroborated by density functional theory (DFT) calculations. Finally, the results were compared with two different asphaltenes and indicate that p-stacking cannot be assumed as the main driving force for asphaltene aggregation.

Synthesis, Trans-Cis Photoisomerization, Fluorescence Decay Studies of Methoxy Ester Functionalized Alkoxy Side Chain Azobenzene Compounds and Their Photoluminescence Dynamics.

In this study, a series of new methoxy ester functionalized core fluorinated, chloro-fluorinated azobenzene derivatives were synthesized. The molecular structures of the azobenzene derivatives (3a-3c and 4a-4c) were confirmed through various analytical methods, with variations in the alkoxy chain length on one end of the aromatic ring. Optical absorption studies of 3a, 3b revealed π-π* transitions around 368-392nm. Further, polarizing optical microscope (POM) studies of 3a, 3b revealed birefringent textures, and their phase transitions were investigated using differential scanning colorimetry (DSC) studies. The trans-to-cis photoisomerization of 3a, 3b transpired over 3600s whereas, thermal back relaxation (cis-to-trans) isomerization took 0.75h. Room temperature photoluminescence (RTPL) studies of 3a-3c and 4a-4c unveiled weak emission intensity peak at ~ 450nm (blue region) when excited at 400nm. Steady-state photoluminescence (SSPL) studies of 3a-3c, 4a-4c revealed a broad emission band in the violet region of the visible spectrum with significantly large Stokes shifts, indicating the presence of highly energized excited states and formation of additional energy levels during photoexcitation. Fluorescence decay (FLD) studies of 3a-3c, 4a-4c unveiled average lifetime (τ) dwells between 8.2 ps and 70.4 ps. The average lifetime (τ) was found to increase with the increase in the length of the alkoxy chain. Phosphorescence decay (PD) profiles of 3a-3c, 4a-4c showed average lifetime (τ) fluctuate around 373 ns to 463 ns. The obtained core fluorinated, chloro-fluorinated azobenzene derivatives having different lengths of the alkoxy side chain can find potential applications in optical storage and display technologies.

Atomistic Simulations of Mechanical Properties of Lignin.

The mechanical properties of lignin, an aromatic heteropolymer constituting 20-30% plant biomass, are important to the fabrication and processing of lignin-based sustainable polymeric materials. In this study, atomistic simulations are performed to provide microscopic insights into the mechanics of lignin. Representative samples of miscanthus, spruce, and birch lignin are studied. At room temperature below the glass transition temperature, the stress-strain curves for uniaxial compression and tensile loading are calculated and analyzed. The results show that lignin possesses rigidity with a Young's modulus in the order of GPa and exhibits strain hardening under strong compression. Meanwhile, lignin is brittle and fails through the microscopic mechanism of cavitation and chain pullout under local tensile loading. In addition to the three common lignin samples, minimalist model systems of monodisperse linear chains consisting of only guaiacyl units and β-O-4 linkages are simulated. Systematic variation of the model lignin chain length allows a focused examination of the molecular weight effects. The results show that the molecular weight does not affect the Young's modulus much, but higher molecular weight results in stronger strain hardening under compression. In the range of molecular weight studied, the lignin chains are not long enough to arrest the catastrophic chain pullout, explaining the brittleness of real lignin samples. This work demonstrates that the recently modified CHARMM force fields and the accompanying structural information of real lignin samples properly capture the mechanics of lignin, offering an in silico microscope to explore the atomistic details necessary for the valorizaiton of lignin.

Cascading Pathways Regulate the Biotransformations of Eight Fluorotelomer Acids Performed by Wastewater Microbial Communities.

Polyfluoroalkyl substances can be biotransformed in natural or engineered environmental systems to generate perfluoroalkyl acids (PFAAs). Data are needed to support the development of biotransformation pathway prediction tools that simulate biotransformation pathways of polyfluoroalkyl substances in specific environmental systems. The goal of this study was to experimentally evaluate the biotransformation of eight structurally similar fluorotelomer acids to identify biotransformation products and propose biotransformation pathways. We selected six fluorotelomer carboxylic acids and two fluorotelomer sulfonic acids and employed a biotransformation test system in which batch reactors are seeded with aerobic wastewater microbial communities. We identified 111 biotransformation products among the eight parent compounds, 58 of which represent unique chemical structures. Many of the biotransformation products are the result of apparent dehydrogenation, monohydroxylation, alcohol oxidation, decarboxylation, HF-elimination, and reductive defluorination biotransformations. We use these data to propose cascading biotransformation pathways that are regulated by integrated and synergistic α-oxidation-like, β-oxidation-like, and defluorination biotransformations that result in the formation of terminal PFAAs of varying chain length. Our data provide a comprehensive view on the aerobic biotransformation of fluorotelomer acids and our results can be used to support the ongoing development of biotransformation pathway prediction tools.

Elucidation of Antimicrobials and Biofilm Inhibitors Derived from a Polyacetylene Core.

The development of new antibiotics with unique mechanisms of action is paramount to combating the growing threat of antibiotic resistance. Recently, based on inspiration from natural products, an asymmetrical polyacetylene core structure was examined for its bioactivity and found to have differential specificity for different bacterial species based on the substituents around the conjugated alkyne. This research further probes the structural requirements for bioactivity through a systematic synthesis and investigation of new compounds with variable carbon chain length, alkynyl subunits, and alcohol substitution. Furthermore, the research examines the activity of the new compounds towards the inhibition of biofilm formation. Overall, several key new polyyne compounds have been identified in both decreasing bacterial viability and in disrupting pre-formed biofilms. These properties are key in the fight against bacterial infections and will be helpful in the further development of new antibiotic agents.

Synergistic enhancing of micellization and thermodynamic properties of some Gemini cationic surfactants related to benzo[d]thiazol-3-ium bromide

Herrin, three Gemini cationic surfactants related to benzo[d]thiazol-3-ium bromide with variable hydrocarbon chain lengths (TBC n = 6, 12, and 18) were synthesized successfully and confirmed by using IR and 1HNMR spectroscopies. Critical micelle concentration and different thermodynamic properties of all surfactants under study were measured using conductivity, density, molal volume, and refractive index techniques. The Critical micelle concentration of TBC 6, TBC 12, and TBC 18 surfactants measured from the different techniques shows an acceptable agreement. The molecular weight of the investigated surfactants was decreased with the order: TBC 18 > TBC 12 > TBC 6. An increase in the magnitudes of the association constant, Gibbs free energy of micellization, molar refraction, polarizability, and binding constant proved the effect of hydrocarbon chain length on increasing surfactant’s micellization as follows: TBC 18 < TBC 12 < TBC 6. The enhancement in surfactant properties was also indicated under the effect of different concentrations of inorganic salts (NaI, NaBr, NaCl, MnCl2, CuCl2, and CoCl2). This effect was measured using conductivity and refractive index measurements. Different salts were indicated to adsorb on head groups of micelles, leading to an increase in the degree of ionization of the surfactant solution and improved aggregation of the surfactant at lower concentrations. The increase in the negative value of Gibbs free energy of association in the presence of salts proved an increase in the stability of micelles formed in a 15% DMSO-water solvent at 298.15 K.

Precisely Tailoring Molecular Structure of Doxorubicin Prodrugs to Enable Stable Nanoassembly, Rapid Activation, and Potent Antitumor Effect.

Achieving a balance between stable drug loading/delivery and on-demand drug activation/release at the target sites remains a significant challenge for nanomedicines. Carrier-free prodrug nanoassemblies, which rely on the design of prodrug molecules, offer a promising strategy to optimize both drug delivery efficiency and controlled drug release profiles. A library of doxorubicin (DOX) prodrugs was created by linking DOX to fatty alcohols of varying chain lengths via a tumor-responsive disulfide bond. In vitro studies assessed the stability and drug release kinetics of the nanoassemblies. In vivo studies evaluated their drug delivery efficiency, tumor accumulation, and antitumor activity in mouse models. In vitro results demonstrated that longer fatty alcohol chains improved the stability of the nanoassemblies but slowed down the disassembly and drug release process. DSSC16 NAs (hexadecanol-modified DOX prodrug) significantly prolonged blood circulation time and enhanced tumor accumulation, with AUC values 14.2-fold higher than DiR Sol. In 4T1 tumor-bearing mouse models, DSSC16 NAs exhibited notably stronger antitumor activity, resulting in a final mean tumor volume of 144.39 ± 36.77 mm3, significantly smaller than that of all other groups (p < 0.05 by ANOVA at a 95% confidence interval). These findings underscore the critical role of prodrug molecule design in the development of effective prodrug nanoassemblies. The balance between stability and drug release is pivotal for optimizing drug delivery and maximizing therapeutic efficacy.

Effect of safflower seed oil on the molecular structural and enzyme hydrolysis properties of maize starch-lipid complexes.

To investigate the impact of safflower seed oil on the structural and digestive properties of complexes formed by fatty acids of varying chain lengths with maize starch, the starch-fatty acid ternary complexes were prepared by a hydrothermal method. The results indicated that safflower seed oil inhibited the complexation of relatively short-chain fatty acids (C10:0, C12:0, and C16:0) with starch, and promoted the complexation of long-chain fatty acids (C18:0). Intriguingly, safflower seed oil showed no significant impact on the formation of linoleic acid (C18:2) complexes, suggesting selective interactions within the starch-fatty acid complexes. In addition, the addition of safflower seed oil did not affect the thermal stability of the complexes, but significantly improved the anti-digestibility properties of the starch-complexes in each group, with the RS content reaching 59.08% in the C16:0 group. In conclusion, this study provides insights for the development of high-quality resist starch-lipid ternary complexes.

The Ether’s Chain Length Effect in Electrolyte for Hard carbon towards Efficient Sodium Storage at Low Temperature

The synergy between ether-based electrolytes (EBEs) and hard carbon (HC) in sodium-ion batteries (SIBs) enhances Coulombic efficiency, durability, and rate capability. Despite these advantages, the intricate relationship of how the molecular structure of ether solvents modifies electrolyte properties and, subsequently, sodium storage performance remains inadequately explored, especially for low-temperature applications, limiting the advancement of EBEs. Our study investigates ethylene glycol ether-based electrolytes with varying chain lengths to understand their influence on reaction kinetics and sodium storage. Notably, HC electrodes paired with NaPF6/ethylene glycol dimethyl ether exhibit superior performance, achieving 247.5 mAh g-1 after 2000 cycles at 1.0Ag-1. Even at -20 °C, these cells exhibit impressive endurance, retaining capacities of 257.5 mAh g-1 in half cells and 75.5 mAh g-1 in full cells at 0.1Ag-1 after 100 cycles, considering the entire mass of active material. Our thorough analysis indicates that the ether solvent with shorter chain length, distinguished by its low solvation-free energy and accelerated ionic kinetics, promotes rapid de-solvation and the formation of an inorganic-rich interface. Through this study, we illuminate the pivotal influence of solvent chain length on sodium storage in hard carbon, contributing to foundational insights towards the design of sophisticated electrolytes for SIBs.

Thermally stable and polar zwitterionic liquid stationary phases for gas chromatography: Understanding the impact of chemical structure.

The chemical structure of nine imidazolium sulfonate and triflimide zwitterionic liquids (ZILs) were systematically tuned to increase their thermal stability for gas chromatography (GC) separations. Substituents for imidazolium and 2-phenylimidazolium cation systems, comprised of alkyl, benzyl, and oligoether groups of varying chain lengths, were studied as stationary phases in GC. Propanesulfonate, ethanesulfonate, and propanetriflimide anions were examined to understand the effect of linker length and nucleophilicity on ZIL thermal stability. Studies were conducted to assess film stability and thermal lability of ZIL stationary phases on fused silica capillaries when exposed to elevated temperatures for prolonged time periods. All stationary phases exhibited relatively poor film stability on untreated capillary surfaces, but most showed repeatable chromatographic retention after stepwise heating from 100 to 200 °C. To understand the thermal degradation pathways of the ZILs, mass spectrometry (MS) was used to monitor the degradation/volatilization of the stationary phase when heated from 40 to 250 °C. Salt-deactivated surfaces were effective at mitigating stationary phase instability, but were observed to participate in the degradation of alkyl functionalized ZILs via nucleophilic attack of the alkyl substituent. This was not observed for oligoether substituted ZILs. Imidazolium propanesulfonate ZILs all underwent degradation through the detachment of the anion system, resulting in the reformation of 1,3-propanesultone. Most ZIL stationary phases degraded below 230 °C, but the cation substituent was observed to play a significant role in overall ZIL thermal stability. For the imidazolium propanetriflimide ZIL, degradation of the anion system occurred prior to the detachment of the entire anion system via elimination and occurred at around 245 °C.

Poly(vinyl benzoate)-b-Poly(diallyldimethyl ammonium TFSI)-b-Poly(vinyl benzoate) Triblock Copolymer Electrolytes for Sodium Batteries

Due to the great source of raw materials, sodium-based batteries are emerging as a competitive technology in the field of energy storage to supplement the rising need for higher energy densities and storage capacities, currently sustained primarily by the well-established lithium-ion technology. Current sodium-based batteries share with lithium-ion technology the safety concerns linked to flammable and toxic liquid electrolytes. Because of their simplicity of processing and low flammability, polymer electrolytes have found a growing research interest. Furthermore, polymers have several structural choices that span from linear homopolymers to more complex architectures like block copolymers, which allow for tailoring of properties and application to a variety of applications.Among the diverse options within polymer electrolytes, block copolymer electrolytes (BCEs) have emerged as particularly promising. BCEs exhibit phase-separated nanostructured morphologies, offering independent tuning of thermal, mechanical, and electrochemical properties—a key advantage for adapting to varied applications.Block copolymers (BCPs) as solid electrolytes for batteries are usually designed to have an ion-solvating block for ion conduction and an ionophobic block for providing mechanical strength.Various polymer chemistries have been explored for ion solvation, with polyethylene oxides, polycarbonates, and poly(ionic liquid)s among the most investigated. In particular, the poly(ionic liquid) poly(diallyldimethyl ammonium bis trifluoromethanesulfonimide), known as PDADMATFSI, has been demonstrated to have great versatility for lithium and sodium batteries.Here, we explore a novel solid polymer electrolyte for sodium batteries based on an ABA triblock copolymer electrolyte, consisting of poly(vinyl benzoate)-b-poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide)-b-poly(vinyl benzoate)PVBx-b-PDADMATFSIy-b-PVBx triblock copolymer. The SPE triblock copolymer comprises a polymerized ionic liquid (PIL) ion-solvating block as an internal block and an ionophilic PVB as an external block, combined with NaFSI salt. The choice of poly(vinyl benzoate) for the mechanical block stems from two key factors. The presence of a benzoate ring in the backbone confers rigidity and mechanical strength to the polymer system. In addition, we anticipate the possibility of coordination of Na ions with the oxygen in the vinyl benzoate block. To study the influence of PVB as a “conductive” mechanical block on the physiochemical and electrochemical properties of polymer electrolytes, we synthesized four different samples with different chain lengths of PVB and PDADMATFSI, and NaFSI was added for evaluation of the polymer compositions in solid polymer electrolytes. The choice of mixed anions (FSI/TFSI) in the system is motivated by previous research showing the superior physiochemical and electrochemical properties of mixed anions systems in ionic liquid-based and polymer electrolytes Four distinct compositions with varying chain lengths of the blocks were synthesized by reversible addition−fragmentation chain-transfer (RAFT) polymerization. The neat copolymers were subsequently mixed with NaFSI in a 2:1 mol ratio of Na to ionic monomer units. Through comprehensive analysis using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR), it was revealed that the ion coordination within the polymer–salt mixtures undergoes changes based on the composition of the starting neat polymer. It was observed that the relative chain length of each block had a significant impact on the Tg and conductivity of the polymer electrolytes. From FTIR and NMR analyses, it was shown that the PVB blocks also coordinated to some extent with the Na+ ions, in particular when MW was higher than that of the PDADMATFSI. Electrochemical evaluations identified the optimal composition for practical application as PVB11.5K-b-PDADMATFSI33K-b-PVB11.5K, showing an ionic conductivity at 70 °C of 4.2 × 10−5 S cm−1. This polymer electrolyte formulation was investigated for sodium in Na|Na symmetrical cells, showing an overpotential of 200 mV at 70 °C at 0.1 mA cm−2. When applied in a sodium–air battery, the polymer electrolyte membrane achieved a discharge capacity of 1.59 mAh cm−2 at 50 °C, indicating the considerable promise and viability of the investigated polymer electrolyte for sodium batteries. This research further opens new avenues for designing novel polymer electrolytes based on block copolymers and reiterates the importance of careful choice of the Mw of each block.

Rhodium-Catalyzed Meta-C-H Arylation of Arenes with Varied Linker Lengths: Bridging Catalytic Selectivity with Structural Diversity.

The directing group (DG)-assisted approach has so far been the major route to achieve selective C-H activation at both proximal and distal positions. While rhodium catalysts are highly effective in DG-assisted ortho-C-H arylation, meta-C-H arylation with rhodium has not yet been reported. In this study, we present the first example of Rh-catalyzed meta-C-H arylation of arenes. We found that the 2-cyanophenyl-based directing group, in conjunction with arylboronic acids, selectively promotes meta-arylation with complete mono-selectivity. Despite significant advancements in meta-C-H activation for substrates with shorter linkers, such as hydrocinnamic acids, benzyl alcohols/amines, etc., meta-C-H activation of substrates with longer alkyl chains remains challenging with limited literature examples. We demonstrated that arenes with varying chain lengths, including conformationally flexible and less rigid ones such as 4-phenylbutanoic acid, 5-phenylvaleric acid, 6-phenylcaproic acid, 3-phenylpropanol, and 4-phenylbutanol underwent meta-arylation with high levels of regiocontrol. From a synthetic perspective, this approach could be valuable as it allows to produce biaryl derivatives of flexible arenes with native functional groups at the meta-position. The synthetic utility of this strategy is demonstrated through the total synthesis of CNBCA, a bioactive compound possessing promising potency against the SHP2 enzyme activity in vitro.

Rhodium‐Catalyzed Meta‐C‐H Arylation of Arenes with Varied Linker Lengths: Bridging Catalytic Selectivity with Structural Diversity

The directing group (DG)‐assisted approach has so far been the major route to achieve selective C‐H activation at both proximal and distal positions. While rhodium catalysts are highly effective in DG‐assisted ortho‐C‐H arylation, meta‐C‐H arylation with rhodium has not yet been reported. In this study, we present the first example of Rh‐catalyzed meta‐C‐H arylation of arenes. We found that the 2‐cyanophenyl‐based directing group, in conjunction with aryl boronic acids, selectively promotes meta‐arylation with complete mono‐selectivity. Despite significant advancements in meta‐C‐H activation for substrates with shorter linkers, such as hydrocinnamic acids, benzyl alcohols/amines, etc., meta‐C‐H activation of substrates with longer alkyl chains remains challenging with limited literature examples. We demonstrated that arenes with varying chain lengths, including conformationally flexible and less rigid ones such as 4‐phenylbutanoic acid, 5‐phenyl valeric acid, 6‐phenylcaproic acid, 3‐phenylpropanol, and 4‐phenylbutanol underwent meta‐arylation with high levels of regiocontrol. From a synthetic perspective, this approach could be valuable as it allows for the production of biaryl derivatives of flexible arenes with native functional groups at the meta‐position. The synthetic utility of this strategy is demonstrated through the total synthesis of CNBCA, a bioactive compound possessing promising potency against the SHP2 enzyme activity in vitro.

Self-Adhesive ILn@MXene multifunctional hydrogel with excellent dispersibility for human-machine interaction, capacitor, antibacterial and detecting various physiological electrical signals in humans and animals

The poor dispersion of MXene in hydrogel weakens the sensitivity and cycling stability of flexible sensors. In this work, we regulated the interlayer spacing of MXene by employing ionic liquids (IL) with varying chain lengths (C=4, 8, 12, 16, 18). It was found that the ILn with a chain length of C=16 caused the most significant change in interlayer spacing during intercalation, effectively inhibiting the self-restacking of MXene and preventing its aggregation. Building on this finding, we developed the A-PS-0.06I16@M hydrogel with a polyacrylic acid (PAA) network and polydopamine-coated silica (PS). The fabrication of a highly stretchable, adhesive, and conductive hydrogel, exhibited excellent mechanical properties, including up to 1903 % stretchability, elastic modulus of 20 kPa and 806 kJ·m−3 toughness. The hydrogel demonstrated superior electrical conductivity (14.8 mS·cm−1) and high sensitivity (GF=7.64), these features make it particularly effective in monitoring human motion signals, electrocardiograms (ECG), electromyograms (EMG), and electrical signals in rats. Moreover, the hydrogel exhibited great potential in human-machine interface (HMI)、capacitor and antibacterial effects under 808 nm near-infrared light irradiation，indicating broad applications in flexible electronics, sensors, and biomedical engineering.

A Systematic Study on the Polymerization Processes and Resulting Polymer Properties of Bioinspired Sesamol and Diamine‐Based Benzoxazines

ABSTRACTBenzoxazine monomers based on sesamol and aliphatic diamines with a systematic variation of chain lengths were synthesized to study the influence of the diamine chain lengths on thermal and thermo‐mechanical properties. Differential scanning calorimetry analysis revealed an even‐odd effect as the melting point for monomers with an odd chain length was at least 35°C lower compared to their even counterparts. In addition, longer diamine chain lengths increased the beginning of the polymerization from 187°C for diaminoethane (DAE) up to 218°C for diaminohexane (DAH). Rheological analysis revealed a short time frame between the melting and polymerization for monomers based on diaminoethane, ‐propane or ‐butane preventing a polymerization. Polymerization was successful for sesamol benzoxazine with diaminopentane (S‐DAPe) and ‐hexane (S‐DAH) resulting polymers with high glass transition temperatures of up to 228°C for poly(S‐DAPe) and 231°C for poly(S‐DAH), respectively. Remarkably, it was found that S‐DAH could also be polymerized at a lower temperature of 155°C yielding a Tg of 175°C. Furthermore, MCC results showed that peak heat release rate and total heat release of the diamine based polybenzoxazines decrease with decreasing chain length. In comparison to other sesamol based benzoxazines the presence of diamine linkers result in bisbenzoxazines with higher Tg.

Quantitative Equivalence and Performance Comparison of Particle and Field-Theoretic Simulations.

Particle and field-theoretic simulations are both commonly used methods to study the equilibrium properties of polymeric materials. Yet despite the formal equivalence of the two methods, no comprehensive comparisons of particle and field-theoretic simulations exist in the literature. In this work, we seek to fill this gap by performing a systematic and quantitative comparison of particle and field-theoretic simulations. In our comparison, we consider four representative polymeric systems: a homopolymer melt/solution, a diblock copolymer melt, a polyampholyte solution, and a polyelectrolyte gel. For each of these systems, we first demonstrate that particle and field-theoretic simulations are equivalent and yield exactly the same results for the pressure and the chemical potential. We next quantify the performance of each method across a range of different conditions including variations in chain length, system density, interaction strength, system size, and polymer volume fraction. The outcome of these calculations is a comprehensive look into the performance of each method and the systems and conditions when either particle or field-theoretic simulations are preferred. We find that field-theoretic simulations are equal to or faster than particle simulations for nearly all of the systems and conditions examined. In many situations, field-theoretic simulations are several orders of magnitude faster than particle simulations, especially if the polymer chains are long, the system density is high, and long-range Coulombic interactions are present. We also demonstrate that field-theoretic simulations are considerably faster at calculating the chemical potential and bypass the challenges associated with particle-based Widom insertion techniques. Taken together, our results provide quantitative evidence that field-theoretic simulations can reach and sample equilibrium considerably faster than particle simulations while simultaneously producing equivalent results.

Fully Non-Fused Ring Electron Acceptors Enable Effective Additive-Free Organic Solar Cells with Enhanced Exciton Diffusion Length.

Low-cost photovoltaic materials and additive-free, non-halogenated solvent processing of photoactive layers are crucial for the large-scale commercial application of organic solar cells (OSCs). However, high-efficiency OSCs that possess all these advantages remain scarce due to the lack of insight into the structure-property relationship. In this work, three fully non-fused ring electron acceptors (NFREAs), DTB21, DTB22, and DTB23, are reported by utilizing a simplified 1,4-di(thiophen-2-yl)benzene (DTB) core with varied alkoxy chain lengths on the thiophene bridge. The material-only costs of these acceptors are only 11-13$ per gram. Importantly, DTB22 has an exciton diffusion length (LD) of up to 25.5nm. The DTB21 and DTB23 exhibit decreased LDs of 20.1 and 23.1nm, respectively. After blending with the polymer donor PBQx-TF, the PBQx-TF:DTB22 film exhibits the fastest hole transfer and the longest carrier recombination lifetime among these OSCs. Consequently, the optimal PBQx-TF:DTB22-based OSC achieves an excellent PCE of 17.00%, which is among the highest values for fully NFREAs. In contrast, the PBQx-TF:DTB21- and PBQx-TF:DTB23-based OSCs show relatively lower PCEs of 15.13% and 15.63%, respectively. Notably, all these OSCs are fabricated using toluene as the solvent, without any additives. Additionally, the DTB22-based OSC also demonstrates good stability, retaining 95% of its initial efficiency after 500 h without encapsulation in a glovebox.