Interchain Hydrogen Bonds Research Articles

Hydration Activates Dual-Confined Shape-Memory Effects of Cold-Reprogrammable Photonic Crystals.

Shape-memory photonic crystals (SMPCs) transform the nanoscale deformation of copolymers into structural color through an undifferentiated response to stimuli; however, activatable selective responses are extremely rare. Herein, activatable dual confined shape-memory effects (CSMEs) derived from the remodeling of the interchain hydrogen bonds (H-bonds) in cold-programmable SMPCs are revealed. The first level is the water-triggered reconstructionof interchain H-bonds, which can activate/lock the collapsed skeleton, showing shape recovery/retention in response to ethanol vapor. The second level is the pressure-induced reorganization ofinterchain H-bonds that results in the recovered skeleton being locked even when exposed to ethanol vapor or water, while the background porous structure can switch between collapse and recovery. Dual CSMEs result from the Laplace pressure difference and the binding effect of interchain H-bonds in the skeleton according to insights of swelling, in situ deformation tracking, multidimensional infrared spectra, and water wetting/evaporation simulations. The signal interference, source code extraction, and color enhancement of structurally colored patterns can be implemented using CSMEs. This work opens up a new method for fabricating activatable responsive structural color and contributes to the expansion of nanophotonic technology in water printing, erasable watermarks, signal amplifiers, and information coding.

Hexagonal crystalline Magnus' green salt analogues prepared from hydroxy-functionalised Pt and Pd complexes.

New Magnus' green salt (MGS) analogues, [M(dabdOH)2][MCl4]·2H2O (dabdOH = (2S,3S)-2,3-diaminobutane-1,4-diol; M = Pd (1) and M = Pt(2)), in which [M(dabdOH)2]2+ and [MCl4]2- are stacked alternately to form linear chains, were obtained as hexagonal plate crystals. The hexagonal shape and large crystal size are unprecedented features as MGS analogues. An unusual trigonal grade separation of chain complexes has been revealed by the structural analysis. 1 and 2 exhibited remarkable yellow and pink colours, respectively, which are derived from weak M⋯M interactions. The dabdOH ligand, which has an additional hydrogen donor group (hydroxy group), produces a multiple-hydrogen-bond network. The combination of intrachain and interchain hydrogen bonds gives a two-dimensional (2D) hydrogen-bond sheet, and each 2D sheet is indirectly connected by hydrogen bonds via lattice water molecules. The OH-functionalised ligand greatly increases the hydrophilicity of the MGS analogues and yields the largest single crystals of all MGS analogues reported so far. The trigonal grade-separated chain structure is likely due to the geometric matching between the periodicity of chains and the short axis width of the chain. This strategy opens up new insight for preparing large crystals of MGS analogues and for constructing trigonal grade-separated nanowires in molecular crystals.

Unravelling the destabilization potential of ellagic acid on α-synuclein fibrils using molecular dynamics simulations.

The aberrant deposition of α-synuclein (α-Syn) protein into the intracellular neuronal aggregates termed Lewy bodies and Lewy neurites characterizes the devastating neurodegenerative condition known as Parkinson's disease (PD). The disruption of pre-existing disease-relevant α-Syn fibrils is recognized as a viable therapeutic approach for PD. Ellagic acid (EA), a natural polyphenolic compound, is experimentally proven as a potential candidate that prevents or reverses the α-Syn fibrillization process. However, the detailed inhibitory mechanism of EA against the destabilization of α-Syn fibril remains largely unclear. In this work, the influence of EA on α-Syn fibril and its putative binding mechanism were explored using molecular dynamics (MD) simulations. EA interacted primarily with the non-amyloid-β component (NAC) of α-Syn fibril, disrupting its β-sheet content and thereby increasing the coil content. The E46-K80 salt bridge, critical for the stability of Greek-key-like α-Syn fibril, was disrupted in the presence of EA. The binding free energy analysis using the MM-PBSA method demonstrates the favourable binding of EA to α-Syn fibril (ΔGbinding = -34.62 ± 11.33 kcal mol-1). Interestingly, the binding affinity between chains H and J of the α-Syn fibril was significantly reduced on the incorporation of EA, which highlights the disruptive ability of EA towards α-Syn fibril. The MD simulations provide mechanistic insights into the α-Syn fibril disruption by EA, which gives a valuable direction for the development of potential inhibitors of α-Syn fibrillization and its associated cytotoxicity.

Preparation and Properties of Vegetable-Oil-Based Thioether Polyol and Ethyl Cellulose Supramolecular Composite Films

Ethyl cellulose (EC), an important biomass-based material, has excellent film-forming properties. Nevertheless, the high interchain hydrogen bond interaction leads to a high glass transition temperature of EC, which makes it too brittle to be used widely. The hydroxyl group on EC can form a supramolecular system in the form of a non-covalent bond with an effective plasticizer. In this study, an important vegetable-oil-based derivative named dimer fatty acid was used to prepare a novel special plasticizer for EC. Dimer-fatty-acid-based thioether polyol (DATP) was synthesized and used to modify ethyl cellulose films. The supramolecular composite films of DATP and ethyl cellulose were designed using the newly-formed van der Waals force. The thermal stability, morphology, hydrophilicity, and mechanical properties of the composite films were all tested. Pure EC is fragile, and the addition of DATP makes the ethyl cellulose films more flexible. The elongation at the break of EC supramolecular films increased and the tensile strength decreased with the increasing DATP content. The elongation at the break of EC/DATP (60/40) and EC/DATP (50/50) was up to 40.3% and 43.4%, respectively. Noticeably, the thermal initial degradation temperature of the film with 10% DATP is higher than that of pure EC, which may be attributed to the formation of a better supramolecular system in this composite film. The application of bio-based material (EC) is environmentally friendly, and the novel DATP can be used as a special and effective plasticizer to prepare flexible EC films, making it more widely used in energy, chemical industry, materials, agriculture, medicine, and other fields.

Secondary Structure in Amyloids in Relation to Their Wild Type Forms.

The amyloid structures and their wild type forms, available in the PDB database, provide the basis for comparative analyses. Globular proteins are characterised by a 3D spatial structure, while a chain in any amyloid fibril has a 2D structure. Another difference lies in the structuring of the hydrogen bond network. Amyloid forms theoretically engage all the NH and C=O groups of the peptide bonds in a chain with two hydrogen bonds each. In addition, the hydrogen bond network is highly ordered-as perpendicular to the plane of the chain. The β-structure segments provide the hydrogen bond system with an anti-parallel system. The folds appearing in the rectilinear propagation of the segment with the β-structure are caused by just by one of the residues in the sequence-residues with a Rα-helical or Lα-helical conformation. The antiparallel system of the hydrogen bonds in the β-structure sections at the site of the amino acid with a Rα- or Lα-helical conformation changes into a parallel system locally. This system also ensures that the involvement of the C=O and H-N groups in the construction of the interchain hydrogen bond, while maintaining a perpendicular orientation towards the plane of the chain. Conformational analysis at the level of the Phi and Psi angles indicates the presence of the conditions for the structures observed in the amyloids. The specificity of amyloid structures with the dominant conformation expressed as |Psi| = |Phi| reveals the system of organisation present in amyloid fibrils. The Phi, Psi angles, as present in this particular structure, transformed to form |Psi| = |Phi| appear to be ordered co-linearly. Therefore, the calculation of the correlation coefficient may express the distribution around this idealised localisation on the Ramachandran map. Additionally, when the outstanding points are eliminated, the part of amyloid chain can be classified as fulfilling the defined conditions. In addition, the presentation of the chain structure using geometric parameters, V-angle-the angle between the planes of the adjacent peptide bonds (angle versus the virtual axis Cα-Cα) and the radius of the curvature R, depending on the size of the angle V, allows for a quantitative assessment of changes during amyloid transformation.

Synthesis and characterization of bioplastic curdlan esters with an introduced flexible carboxylic acid side chain

Curdlan, a linear β-1,3-glucan, was reacted with glutaric anhydride and heptanoyl chloride to afford thermoplastic curdlan esters (CrdE(HepGlu)) with a carboxylic acid side chain. CrdE(HepGlu) with a degree of substitution of the glutaric acid monoester moiety (DSGlu) in the range of 0–0.58 and that of the heptanoate moiety (DSHep = 3 − DSGlu) was prepared. The esterification of the hydroxy groups in the glucan skeleton effectively caused the cleavage of the interchain hydrogen bonds of curdlan and enhanced the formability of CrdE(HepGlu). Moreover, the flexible carboxylic acid side chain moderately affected hydrogen bonding. Thus, the glass transition temperature of CrdE(HepGlu), estimated by differential scanning calorimetry, increased with increasing DSGlu. CrdE(HepGlu) with DSGlu between 0 and 0.58 displayed high solubility in organic solvents and thermoplasticity, enabling the formation of homogeneous and free-standing films by solution casting. The mechanical properties of CrdE(HepGlu) films were evaluated by a stress−strain test, which showed that Young's modulus and the maximum stress increased with increasing DSGlu. CrdE(HepGlu) exhibited higher mechanical strength than non-hydrogen-bonded curdlan triheptanoate and hydrogen-bonded curdlan alkylcarbamates, with thermal stability comparable to that of thermally stable curdlan esters. In addition, these properties can be regulated by controlling DSGlu.

Construction of multiresponsive supramacromolecular hydrogels with a novel azobenzene derivative as crosslinkers

Supramacromolecular hydrogels (SMHGs) are attractive materials in various areas. Due to their excellent reversible photoisomerization ability, azobenzene derivatives have been widely applied to construct SMHGs. But the majority of these systems were realized only by transplanting azobenzene function groups into macromolecule chains, while low-molecular-weight (LMW) azobenzene derivatives are fairly rare. Therefore, it is highly desirable to develop facile and effective strategies for the construction of SMHG. Here, a new ABA-typed azobenzene derivative (AD) has been designed and synthesized, which can be applied as LMW crosslinkers to construct SMHGs through electrostatic interactions between AD and sodium alginate (SA). When AD is mixed with SA solution in acidic conditions, SMHGs can form at various concentrations of SA. In addition, the concentration of AD also has a large impact on the moduli values. Profiting from electrostatic interactions between AD and SA, as well as interchain hydrogen bonds of SA, SMHGs can experience sol-gel transitions under pH-, photo- or thermo-stimuli. This work contributes a simple but effective strategy for the construction of SMHGs using azobenzene derivatives as LMW crosslinkers.

Cellulose Fast Pyrolysis Activated by Intramolecular Hydrogen Bonds.

The conversion of inedible biomass by fast pyrolysis is a promising route for sustainable production of renewable fuels and value-added chemicals, but low selectivity toward desired products hampers its economic viability. Understanding the molecular-level reaction pathways of biomass fast pyrolysis could be the key to overcoming this challenge. However, the effects of intramolecular and interchain hydrogen bonds near the reaction center have not been thoroughly explored. In this work, the reaction pathways and kinetics of fast pyrolysis of cellulose, a major component of biomass, were investigated using the density functional theory. A new intramolecular hydroxyl-activated mechanism is presented for cellulose activation. Our calculations incorporating noncovalent interactions accurately captured the activation energy of 50.8 kcal mol-1, agreeable with the apparent activation energy measured experimentally. The findings of cellulose pyrolysis provide insights into the investigation of interactions during real-life biomass pyrolysis.

Non-Covalent Bond-Regulated Solar Evaporation Modulator: Facilitative Hydration Domains Originated via a Homogeneous Polymeric Network.

The solar-driven evaporation technology provides a green alternative for solving water scarcity. However, it remains challenging to improve the steam conversion efficiency due to the difficulties in simultaneously coordinating light absorbance, water regulation, and thermal management for broadband solar evaporators. Here, an unconventional solar evaporative modulator material─ultra-interfacial adherent dimethyl sulfoxide polyvinyl alcohol (DMSO-PVA) hydrogel (DPH) was presented. The material is based on the regulation of the PVA-PVA intra- and PVA-water interchain hydrogen bonds by DMSO, which established an adaptive high-cross-linking and homogeneous network. The consequent ultra-thin hydrogel exploited an insulating polymer backbone and intracavity hydration domain to simultaneously improve the light absorption and thermal localization and activate the water molecule. As a proof-of-concept, under 1 sun illumination (1 kW m-2), a DPH-based graphene fiber membrane [ultra-thin hydrogel membrane (UHM)] achieved 97% light absorption, 2.33 kg m-2 h-1 water evaporation, and high salt-resistant evaporation (1.48 kg m-2 h-1 under 25 wt % brine). Compared to the pure graphene membrane, UHM increased the vaporization by 64%, decreased the heat diffusion by over 14-folds, and reduced the environmental heat loss by 2.6-folds. DPH possesses scalability and versatility in bridging nanoscale photothermal materials and solar evaporator geometric architecture and will facilitate the possibility of advanced solar thermal applications.

A Molecular Dynamics Simulation Study of Amine-Carboxyl Ionic Interactions and Their Distribution in a Polysiloxanes Network

The ionic crosslinking mechanism of polysiloxanes networks based on amine/carboxyl interactions was investigated by molecular dynamics and tensile performance experiments. The “one-chain-crosslinking” mechanism between crosslinkers and polymers was investigated based on the corresponding simulations. The experimental results showed that the tensile strength and elongation at break of amine-functional polysiloxanes (AFPs)/carboxyl-functional polysiloxanes (CFPs) (1.54 MPa@264%, respectively) were higher than that of amine and carboxyl-functional polysiloxanes (ACFPs) (0.66 MPa@45%). The simulation results indicated that the number of intrachain and interchain hydrogen bonds played an important role for improving the mechanical performance of the polymer networks. In addition, it was found that the orientation and entanglement of the polymer chains had a direct correlation with hydrogen bonding in the equilibrium state and during the stretching process. The mean square radius of gyration (R g2), the mean square end-to-end distance (R ee2), the orientation parameter, the entanglement parameter, and the mean square displacement (MSD) of the chains in the equilibrium state were calculated. The molecular dynamic simulations were verified by comparing the simulated results with the tensile and rheological experimental results of the AFPs/CFPs and ACFPs elastomers.

Application study of infrared free-electron lasers towards the development of amyloidosis therapy.

Amyloidosis is known to be caused by the deposition of amyloid fibrils into various biological tissues; effective treatments for the disease are little established today. An infrared free-electron laser (IR-FEL) is an accelerator-based picosecond-pulse laser having tunable infrared wavelengths. In the current study, the irradiation effect of an IR-FEL was tested on an 11-residue peptide (NFLNCYVSGFH) fibril from β2-microglobulin (β2M) with the aim of applying IR-FELs to amyloidosis therapy. Infrared microspectroscopy (IRM) and scanning electron microscopy showed that a fibril of β2M peptide was clearly dissociated by IR-FEL at 6.1 µm (amide I) accompanied by a decrease of the β-sheet and an increase of the α-helix. No dissociative process was recognized at 6.5 µm (amide II) as well as at 5.0 µm (non-specific wavelength). Equilibrium molecular dynamics simulations indicated that the α-helix can exist stably and the probability of forming interchain hydrogen bonds associated with the internal asparagine residue (N4) is notably reduced compared with other amino acids after the β-sheet is dissociated by amide I specific irradiation. This result implies that N4 plays a key role for recombination of hydrogen bonds in the dissociation of the β2M fibril. In addition, the β-sheet was disrupted at temperatures higher than 340 K while the α-helix did not appear even though the fibril was heated up to 363 K as revealed by IRM. The current study gives solid evidence for the laser-mediated conversion from β-sheet to α-helix in amyloid fibrils at the molecular level.

The Synthesis and Properties of a New Carrier for Paclitaxel and Doxorubicin Based on the Amphiphilic Copolymer of N‐vinyl‐2‐pyrrolidone and Acrylic Acid

AbstractThis paper deals with the development of polymeric nanocarriers based on amphiphilic copolymers of N‐vinyl‐2‐pyrrolidone and acrylic acid of various molecular weights synthesized through the AIBN‐initiated radical copolymerization of N‐vinyl‐2‐pyrrolidone and acrylic acid in the presence of n‐octadecyl mercaptan. The structure of the copolymers is characterized by 1Н NMR, 13С NMR, IR and MALDI‐TOF MS spectroscopy. It is shown that the length of the hydrophilic block defines the size of the nanoaggregates while impacting the steric stabilization efficiency and the probability of the interchain hydrogen bond formation. The hydrogen bonds formation between the residues of N‐vinyl‐2‐pyrrolidone and acrylic acid is in agreement with the reduction of the ζ‐potential of the nanoaggregates and the critical aggregation concentrations upon increasing the molecular weight. The presence of acrylic acid residues in the amphiphilic macromolecules leads to a higher affinity for doxorubicin and slow partial release of doxorubicin bonded with the aggregates’ corona, which is helpful for reducing its cardiac toxicity. Nanoaggregates with a paclitaxel‐loaded hydrophobic core are obtained, showing the possibility of dual loading. The amphiphilic copolymers of N‐vinyl‐2‐pyrrolidone and acrylic acid containing an n‐octadecyl thio end group are thus promising candidates for combination cancer therapy with immobilized anti‐cancer drugs, paclitaxel, and doxorubicin.

Water transport in epoxy/polyurethane interpenetrating networks

AbstractDiffusion of water in epoxy–polyurethane (PU) interpenetrating networks was investigated using gravimetry, time‐resolved ATR‐FTIR, and 2D correlation analysis. In this study, the amount of PU component and the length of polyethylene oxide soft block in them were systematically varied to determine their influence on water uptake. The diffusion coefficients were calculated and anomalous water diffusion is well described by the Carter and Kibler model. Water molecules of four different states were identified in the network volume, and sequence of their formation was determined by 2D‐IR spectroscopy. One of them could be confined into free volume (microvoids) or molecularly dispersed with hydrogen‐bonding at cluster formation (bulk dissolved), while the others could be attributed to the bound water forming strong hydrogen bonds with hydrophilic entities of networks. These results were supported by solid‐state 2H NMR data. The influence of water uptake on thermomechanical behavior of epoxy/PU networks was determined. It was shown that the increase of PU content in composites leads to the changes of the effect of water uptake from plasticizing to the anti‐plasticizing as a result of the formation of new networks of interchain hydrogen bonds.

Insights on the cellulose pretreatment at room temperature by choline-chloride-based deep eutectic solvents: an atomistic study

The pretreatment or disruption of a cellulose I \(\beta \) crystallite by four deep eutectic solvents (DES): choline-chloride ethylene glycol, choline-chloride oxalic acid, choline-chloride urea, and choline-chloride levulinic acid, was described from the atomistic interactions observed in molecular dynamics and ab-initio (NCI-AIM) studies. The cellulose I \(\beta \) disruption was studied considering plausible correlations between the Kamlet-Taft (α and β) solvent parameters, and a series of thermodynamic, structural, and energetic properties. It was found that the Kamlet-Taft parameters correlated with the thermodynamic properties of the DES, as well as their variations after the addition of the cellulose crystallite. Structural analysis revealed that the weaker the interactions within the molecules of the solvent, the stronger the interactions between the hydroxyl group from cellulose with the chloride anion and with the hydrogen bond donor. Further analysis indicated that the \(R-CO-R\) moieties in the hydrogen bond donor within the solvent, displayed best interplaying with the cellulose. The hydrogen bond occupancies within the cellulose crystallite, evidenced that the main \(O6-H6\cdots O2/O3\) and \(O2-H2\cdots O6\) interchain hydrogen bonds in the glucan located at the edge of the solute, were replaced by weak \(O6-H6\cdots O4\) hydrogen bonds in all solvents. This effect was related to the \({O/Cl}_{DES}\cdots H-donor\) and \({O}_{DES}-{H}_{DES}\cdots acceptor\) HBs between cellulose and DES molecules, and it was confirmed by the non-covalent interactions obtained through DFT calculations. The energetic interactions and the atomistic degree of disruption of the cellulose crystallite, were not completely described by the Kamlet-Taft β or α parameters when considered separately. Surprisingly, by using the net basicity (\(\beta -\alpha \)) definition such correlations were improved, suggesting that both parameters must be considered together to develop new, green, and sustainable solvents for cellulose pretreatment process.Graphic abstract

Effects of quinoa protein Pickering emulsion on the properties, structure and intermolecular interactions of myofibrillar protein gel

The effects of quinoa protein Pickering emulsion (QPE) on the gel properties, protein structure and intermolecular interactions of myofibrillar protein (MP) gels were studied. Compared with the MP gels without QPE, the MP gels with 5.0%-7.5% added QPE showed significant increasing trends in storage modulus (G′), whiteness, gel strength and water holding capacity (WHC). The content of disulfide bonds in the gel increased with the addition of QPE and the disulfide bond conformation changed from gauche-gauche-gauche to gauche-gauche-trans. Moreover, the increase of hydrogen bonds after QPE addition confirmed the transformation from α-helix to β-sheet, as β-sheet structure was stabilized by interchain hydrogen bonds. The added QPE also enhanced the hydrophobic interaction and electrostatic interaction of MP gels. To conclude, the addition of 5.0%–7.5% QPE improved the intermolecular interactions and the structure stability of MP gels, and enhanced the gelation and WHC of MP gels.

Molecular Dynamics Study of Cellulose Nanofiber Alignment under an Electric Field.

The alignment of cellulose by an electric field is an interesting subject for cellulose material processing and its applications. This paper reports an atomistic molecular dynamics simulation of the crystalline cellulose nanofiber (CNF) model in varying electric field directions and strengths. GROMACS software was used to study crystalline cellulose 1β consisting of 18 chains in an aqueous environment at room temperature, and an electric field was applied along the cellulose chain direction and the perpendicular direction with varying field strength. The root-mean-square displacement, radius of gyration, end-to-end length, and hydrogen bond population of the crystalline CNF model were analyzed to determine the effects of the applied electric field on the structure of the CNF model. The results suggest that the nanosecond electric field can induce the orientation of the CNF along the applied electric field direction. The alignment rate and ability to maintain the alignment depend on the electric field strength. Analysis of the radius of gyration, end-to-end length, and bond lengths for intrachain and interchain hydrogen bonds revealed no significant effect on the cellulose structure. Cellulose alignment in an electric field has the potential to broaden the design of electric field-induced processing techniques for cellulose filaments, thin films, and electro-active cellulose composites.

Interchain hydrogen-bonded conjugated polymer for enhancing the stability of organic solar cells

Operational stability of organic solar cells (OSCs) is a key issue for the commercialization. In order to enhance the stability of OSCs, various strategies are being used. In this study, pyrroles and isoindigo monomers with tert-butoxycarbonyl side chains were synthesized and used to prepare a D–A-type polymer, P(TBPyTBIID), via Stille coupling. The obtained polymer dissolved readily in organic solvents, such as chloroform. However, the formation of interchain hydrogen bonds after side-chain cleavage via thermal treatment rendered the resulting polymer insoluble in organic solvents. In addition, strong π⋯π stacking due to face-on orientation enabled dense packing of the structure, which led to an increase in resistances to organic solvents, acid, and ultraviolet (UV) light. P(TBPyTBIID) was introduced as a UV and external protective layer, along with silver nanoparticles, at the back surface of the glass substrate. The light-soaking stability was enhanced without significantly reducing the efficiencies of the organic solar cells. This work indicates that introducing an UV blocking layer can be an effective strategy to increase the stability of organic solar cells.

Molecular alignment induced high thermal conductivity in amorphous/ low crystalline polyimide fibers

It is of considerable scientific and technological importance to enhance the thermal conductivity (k) of polymers for the application in thermal management. In this work, we study the thermal transport in amorphous/low-crystalized polyimide (PI) composite fibers (crystallinity lower than 2%-10%) by using the transient electro-thermal (TET) technique and the steady-state electro-thermal (SET) technique from 320 K to 7 K. It is found that the amorphous/low-crystalized PI fibers can achieve a high k (2.13 W/m K) due to oriented chain alignment and inter-chain hydrogen bonds from the condensation polymerization, wet-spinning and low-ratio thermal drawing process. By using the thermal reffusivity (Θ) model, the phonon propagation in PI fibers is investigated. The structural domain size (SDZ) of the amorphous/low-crystalized PI fibers is determined based on the residual Θ at 0 K limit, which is calculated to be 3.85 nm and 9 nm for the undrawn and post-drawn PI fiber, respectively. The SDZ value is close to the radius of gyration (Rg) instead of the atomic scale characteristic length of PI. This result indicates that for amorphous/low crystalized PI fibers with hydrogen bonds, the Rg could have played a more important role in determining k.

Nonvolatile, stretchable and adhesive ionogel fiber sensor designed for extreme environments

Stretchable conductive sensors based on iontronics are key components for next generation sensing systems in wearable devices or soft robots. Considering the narrow working temperature range of hydrogels-based ionic conductors, ionogel with inherent non-volatility and survivability over a wide temperature range, is proposed to prepare gel fiber-based sensor, via exceedingly simple mold method. Zwitterionic monomer [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) (SBMA) and acrylamide (AM) were selected to construct the crosslinked ionogel networks. The ion–dipole, dipole–dipole interactions and interchain hydrogen bonds introduced in the ionogel fiber (IGF) system, simultaneously improve the gel strength and endow the IGF with distinctive properties. The resultant IGF exhibits unique self-adhesiveness, excellent transparency, tunable mechanical properties and ultrahigh stability in various extreme environments. Moreover, as a strain sensor, the as-fabricated IGF is characteristic by outstanding sensitivity with a gauge factor (GF) of 6.20, low detection threshold (0.5% strain) and high durability (1000 cycles at 100% strain). The sensor works well in harsh environments, exhibiting an enlarged working temperature range (–80 ∼ 150 °C) and high tolerance under vacuum (1.325 kPa). We anticipate this IGF-based sensor to make up for the vacancy of flexible sensors in extreme circumstances, thus expanding more application scenarios.

Electrochemical and X-ray Photoelectron Spectroscopy Surface Characterization of Interchain-Driven Self-Assembled Monolayer (SAM) Reorganization.

Herein, we report a combined strategy encompassing electrochemical and X-ray photoelectron spectroscopy (XPS) experiments to investigate self-assembled monolayer (SAM) conformational reorganization onto an electrode surface due to the application of an electrical field. In particular, 3-mercaptopriopionic acid SAM (3MPA SAM) modified gold electrodes are activated with a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHSS) (EDC-NHSS) mixture by shortening the activation time, from 2 h to 15/20 min, labelled as Protocol-A, -B and -C, respectively. This step, later followed by a deactivation process with ethanolamine (EA), plays a key role in the reaction yields (formation of N-(2-hydroxyethyl)-3-mercaptopropanamide, NMPA) but also in the conformational rearrangement observed during the application of the electrical field. This study aims at explaining the high performance (i.e., single-molecule detection at a large electrode interface) of bioelectronic devices, where the 3MPA-based SAM structure is pivotal in achieving extremely high sensing performance levels due to its interchain interaction. Cyclic voltammetry (CV) experiments performed in K4Fe(CN)6:K3Fe(CN)6 for 3MPA SAMs that are activated/deactivated show similar trends of anodic peak current (IA) over time, mainly related to the presence of interchain hydrogen bonds, driving the conformational rearrangements (tightening of SAMs structure) while applying an electrical field. In addition, XPS analysis allows correlation of the deactivation yield with electrochemical data (conformational rearrangements), identifying the best protocol in terms of high reaction yield, mainly related to the shorter reaction time, and not triggering any side reactions. Finally, Protocol-C’s SAM surface coverage, determined by CV in H2SO4 and differential pulse voltammetry (DPV) in NaOH, was 1.29 * 1013 molecules cm−2, being similar to the bioreceptor surface coverage in single-molecule detection at a large electrode interface.