Cross-linked Structure Research Articles

Polyphosphazene Microparticles with High Free Radical Scavenging Activity for Skin Photoprotection.

Ultraviolet (UV) filters are the core ingredients in sunscreens and protect against UV-induced skin damage. Nevertheless, their safety and effectiveness have been questioned in terms of their poor photostability, skin penetration, and UV-induced generation of deleterious reactive oxygen species (ROS). Herein, an organic UV filter self-framed microparticle sunblock was exploited, in which quercetin (QC) and hexachlorocyclotriphosphazene (HCCP) were self-constructed into microparticles (HCCP-QC MPs) by facile precipitation polymerization without any carriers. HCCP-QC MPs could not only significantly extend the UV shielding range to the whole UV region but also remarkably reduce UV-induced ROS while avoiding direct skin contact and the resulting epidermal penetration of small-molecule QC. Meanwhile, HCCP-QC MPs possess a high QC-loading ability (697 mg g-1) by QC itself as the microparticles' building blocks. In addition, there is no leakage issue with small molecules due to its covalently cross-linked structure. In vitro and vivo experiments also demonstrated that the HCCP-QC MPs have excellent UV protection properties and effective ROS scavenging ability without toxicity. In summary, effective UV-shielding and ROS scavenging ability coupled with excellent biocompatibility and nonpenetration of small molecules make it a broad prospect in skin protection.

Biobased polysulfides prepared via inverse vulcanization with properties of intrinsic self-extinguishment and thermal remodeling

Developing high-performance polymers with intrinsic self-extinguishment and thermal remodeling from biobased resources has attracted increasing attention due to both safety and environmental concerns. In this work, two biobased crosslinkers, trieugenylcyanuric (TEC) and trieugenylphosphate (TEP), were designed and synthesized, and then five novel biobased polysulfides were synthesized via inverse vulcanization with different combinations of elemental sulfur, eugenol (Eug) and crosslinkers. The chemical structure of crosslinkers and polysulfides were confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopies (FT-IR), respectively. In addition, molecular weight of the linear polysulfide was measured by gel permeation chromatography (GPC). Various techniques, such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), microscale combustion calorimeter (MCC) and scanning electron microscopy (SEM) were used to characterize the properties of the polysulfides. Notably, the crosslinked polysulfide (P(S-TEP)) shows self-extinguishment with heat release apacity (HRC) value of 165 J/g⋅K and total heat release (THR) value of 7.9 kJ/g, and it can melt completely at 180℃ (thermal remodeling) without any extra treatment. Overall, the current work provides a high-efficiency and sustainable synthetic route access to a series biobased polysulfides with self-extinguishment and thermal remodeling.

Mechanochemical Recycling of Flexible Polyurethane Foam Scraps for Quantitative Replacement of Polyol Using Wedge-Block-Reinforced Extruder.

Recycling flexible polyurethane foam (F-PUF) scraps is difficult due to the material's high cross-linking structure. In this work, a wedge-block-reinforced extruder with a considerable enhanced shear extrusion and stretching area between the rotating screw and the stationary wedge blocks was utilized to recycle F-PUF scraps into powder containing surface-active hydroxyl groups. The powder was then utilized for the quantitative replacement of polyol in the foaming process. Characterizations showed that the continuous shear extrusion and stretching during the extrusion process reduced the volume mean diameter (VMD) of the F-PUF powder obtained by extruding it three times at room temperature to reach 54 μm. The -OH number (OHN) of the powder prepared by extruding it three times reached 19.51 mgKOH/g due to the mechanochemical effect of the powdering method. The F-PUF containing recycled powder used to quantitively replace 10 wt.% polyol was similar in microstructure and chemical structure to the original F-PUF, with a compression set of 2%, indentation load deflection of 21.3 lbf, resilience of 43.4%, air permeability of 815.7 L/m2·s, tensile strength of 73.0 Kpa, and tear strength of 2.3 N/cm, indicating that the recycling method has potential for industrial applications.

Effects of Aging on Rheological Properties and Microstructural Evolution of SBS Modified Asphalt and Crumb Rubber Modified Asphalt Binders

Focusing on the comparison of aging resistance between styrene-butadiene-styrene (SBS) modified asphalt (SBSMA) and crumb rubber modified asphalt binders (CRMA), the influences of aging on rheological properties and microstructural characteristics of different modified asphalts were investigated in this work. Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) tests were carried out, and the variations in rheological properties for different modified asphalts after the rotating thin film oven test (RTFOT) were analyzed with the rutting factor aging index (RAI) and creep rate aging index (CAI). By using Fluorescence microscopy (FM) and Fourier transform infrared (FTIR) spectroscopy, the evolutions of microstructure and chemical composition for two modified asphalts were analyzed with carbonyl index growth rate (CIR) and sulfoxide index growth rate (SIR). Then, The relationships between CIR/SIR and RAI/CAI were established to show the correlation between the deterioration of macroscopic performance and the evolution of micro-structure. The results indicated that the aging degree of asphalt increases with elevated temperatures, leading to decreasing low-temperature performance while improving high-temperature performance. Nevertheless, SBSMA exhibited strong sensitivity to aging temperature. Under thermo-oxidative aging, the RAI and CAI of SBSMA were lower than those of CRMA, whereas the regularities of CIR and SIR were opposite, indicating that CRMA was superior to SBSMA in terms of anti-aging properties due to the rupture of the cross-linked network structure of SBSMA. However, CRMA experienced aging accompanied by full swelling, and thus, relatively minor performance declined. The CIR and SIR exhibited a better correlation with the RAI and CAI, illustrating that both CIR and SIR could characterize the aging degree of modified asphalts well.

Preparation of Cross-Linked Sodium Alginate Microspheres with Different Metal Ions Using the Microfluidic Electrospray Technology.

Microspheres are micrometer-sized particles that can load and gradually release drugs via physical encapsulation or adsorption onto the surface and within polymers. In the field of biomedicine, hydrogel microspheres have been extensively studied for their application as drug carriers owing to their ability to reduce the frequency of drug administration, minimize side effects, and improve patient compliance. Sodium alginate (ALG) is a naturally occurring linear polysaccharide with three backbone glycosidic linkages. There are two auxiliary hydroxyl groups present in each of the moieties of the polymer, which have the characteristics of an alcohol hydroxyl moiety. The synthetic ALG units can undergo chemical cross-linking reactions with metal ions, forming a cross-linked network structure of polymer stacks, ultimately forming a hydrogel. Hydrogel microspheres can be prepared using a simple process involving the ionic cross-linking properties of ALG. In this study, we prepared ALG-based hydrogel microspheres (ALGMS) using a microfluidic electrodeposition strategy. The prepared hydrogel microspheres were uniformly sized and well-dispersed, owing to accurate control of the microfluidic electrospray flow. ALGMS cross-linked with different metal ions were prepared using a microfluidic electrospray technique combining microfluidic and high electric field, and its antimicrobial properties, slow drug release ability, and biocompatibility were investigated. This technology holds promise for application in advanced drug development and production.

Oxidized Starch-Reinforced Aqueous Polymer Isocyanate Cured with High-Frequency Heating.

In this research, an oxidized starch/styrene-butadiene rubber system with high capability of absorbing electromagnetic energy was adopted as the main component, the effect of oxidized starch content on the bonding and mechanical properties of aqueous polymer isocyanate (API) after high-frequency curing was evaluated, and the effect mechanisms were explored by combining thermodynamic tests and material characterization methods. Our findings revealed that the addition of oxidized starch enhanced the mechanical properties of API after high-frequency curing and the increase in the amount of oxidized starch enhanced the improvement effect of high-frequency curing on API bonding and mechanical properties. At 5 wt% oxidized starch, high-frequency curing improved API bonding properties by 18.0% and 17.3% under ambient conditions and after boiling water aging, respectively. An increase in oxidized starch content to 25 wt% increased enhancement to 25.1% and 26.4% for the above conditions, respectively. The enhancement effects of tensile strength and Young's modulus of the API adhesive body were increased from 9.4% and 18.2% to 18.7% and 22.6%, respectively. The potential enhancement mechanism could be that oxidized starch could increase the dielectric loss of API, converting more electromagnetic energy into thermal energy creating more cross-linked structures.

Thermal curing mechanisms and cross-linking network structure of a novel silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene unit

Silicon-containing arylacetylene resin and its composites have attracted great interest as emerging heat-resistant materials, but their curing mechanisms and products are still elusive. In this work, the influences of the terminal and inner acetylenes on the curing mechanisms of silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene were first identified by density functional theory. Two reaction pathways were proposed and their products include polyenes, anthracene dimers, and benzene trimers. To gain a distinct observation of the cross-linking process, molecular dynamics simulations were used to construct a cross-linking polymerization model. The effects of the temperature on the cured structure were investigated by analyzing the characteristics of the cross-linked network. As expected, higher curing temperature will make the larger proportion of polyene chain and aromatic ring in the terminal alkyne−terminal alkyne route, meanwhile, for the inner alkyne−inner alkyne route, the short chains and a small amount of aromatic rings are major productions. Overall, our cross-linking method may provide an unique guidance for studying the cured structure of other thermosetting resins.

Aptamer responsive DNA Functionalized hydrogels electrochemiluminescence biosensor for the detection of adenosine triphosphate

DNA hydrogel represents a noteworthy biomaterial. The preparation of biosensors by combining DNA hydrogel with electrochemiluminescence can simplify the modification process and raise the experimental efficiency. In this study, an electrochemiluminescence (ECL) biosensor based on DNA hydrogel was fabricated to detect adenosine triphosphate (ATP) simply and quickly. CdTe–Ru@SiO2 nanospheres capable of ECL resonance energy transfer (RET) were synthesized and encapsulated CdTe–Ru@SiO2 in the DNA hydrogel to provide strong and stable ECL signals. DNA hydrogel avoided the labeling of ECL signal molecules. The aptamer of ATP as the linker of the hydrogel for the specificity of ATP detection. The cross-linked structure of the aptamer and the polymer chains was opened by ATP, and then the decomposition of the DNA hydrogel initiated the escape of CdTe–Ru@SiO2 to generate an ECL signal. The designed biosensor detected ATP without too much modification and complex experimental steps on the electrode surface, with good specificity and stability, and a wide linear range. The detection range was 10–5000 nM, and the detection limit was 6.68 nM (S/N = 3). The combination of DNA hydrogel and ECL biosensor provided a new way for clinical detection of ATP and other biomolecule.

Visualization of crack generation of vulcanized butadiene rubber under uniaxial elongation by atomic force microscopy nanomechanics

Crack resistance performance by oxidation must be considered in rubber product development because cracks are the starting point for fracture. When rubber is stretched extensively, mechanical stresses can break apart its molecular chains, generating radicals and promoting mechanochemical oxidation. This reaction is one of the causes of cracking. However, it is not fully understood how cracks are formed in vulcanized rubber with an inhomogeneous crosslinking structure. Atomic force microscopy (AFM) nanomechanics has been utilized to observe vulcanized butadiene rubber in an elongated state. It was shown that crack generation is related to mechanochemical oxidation, and that the cracks could be clearly visualized as stress-concentrated regions at the nanoscale. Additionally, crack formation is accelerated with increasing elongation of the rubber. This demonstrates that AFM nanomechanics is an effective tool for observation of the generation of cracks associated with mechanochemical oxidation in rubber materials.

Tailoring stability in oil-in-water high internal phase Pickering emulsions (HIPPEs) through surface modification of beeswax-based solid lipid particles (SLPs) with various surfactants

As high-performance Pickering stabilizers, the exploration of solid lipid particles (SLPs) for oil-in-water high internal phase emulsions (HIPPEs) has garnered significant interest in the colloid domain, primarily owing to their promising applications in the food industry. Herein, as an underutilized and cost-effective food processing resource, beeswax (BW) was probed, and BW-SLPs was tuned by controlling the different type (Na-Cas or T80)/concentration (0.5–2.5 wt%) of surfactant with a view to stabilizing the HIPPEs (φ = 0.80) more effectively. At concentrations of 0.5–2.0 wt%, a more stable semi-solid HIPPEs could be formed by Na-Cas-BW-SLPs, while phase separation occurred at 2.5 wt%. However, T80-BW-SLPs could only form the fluid dynamic emulsions. The correlation between the interfacial characteristics of SLPs and the physical properties of SLPs-stabilized HIPPEs was thoroughly investigated. Microscopic images showed that Na-Cas-BW-SLPs formed a closely packed three-dimensional network structure around the oil droplets but aggregated in the aqueous phase at the concentration of 2.5 wt%. And they exhibited the capacity to improve the viscoelasticity of the interfacial film, which also endowed the HIPPEs with excellent rheological properties. While, T80-BW-SLPs were loosely arranged, formed a viscous film on the interface, and G′ of the interfacial film was about 2 orders of magnitude lower than Na-Cas-HIPPEs at the same concentration. Besides, transmission electron microscopy (TEM) analysis revealed that the Na-Cas-BW-SLPs (∼370 nm), unlike the out of shape T80-BW-SLPs (∼230 nm), exhibited a cross-linked structure with a rough surface. All SLPs demonstrated enhanced wettability and a remarkable ability to reduce interfacial tension (2 mN/m). Additionally, it further identified the inability to form stable HIPPEs up to φ = 0.84 at the optimal Na-Cas-SLPs concentration. Ultimately, the HIPPE stabilized by 3.0 wt% BW and 2.0 wt% Na-Cas, with oil fraction up to 83 vol%, exhibited the highest elastic modulus (3871.0 Pa) and demonstrated exceptional stability over a 30-day storage period.

In situ crosslinking of silica aerogel with reactive carbon fiber for high mechanical property, thermal insulation and superhydrophobicity

In this study, a novel silicon hydroxyl groups decorated long carbon chain grafted carbon fiber was synthesized, and a facile fabrication method was developed to produce reactive carbon fiber-silica aerogel composite with chemical crosslinking structure. Scanning electron microscopy images showed that silica aerogel matrix is wrapped on the surface of reactive carbon fibers. The reactive carbon fibers facilitated obstacle in shrinkage, and aerogel composites exhibited microporous behavior with average diameter of about 1.8 nm. Fourier-transform infrared and X-ray photoelectron spectroscopy confirmed the strong interfacial interaction between reactive carbon fibers and silica matrix. The modification mechanism of silicon hydroxyl groups decorated long carbon chain grafted carbon fiber, and the chemical crosslinking in aerogel composite were proposed. The reactive carbon fiber-silica aerogel composites synthesized in this work had been proved to have low density, excellent mechanical property, good tailoring performance, improved thermal stability, low thermal conductivity, high flame retardancy, high thermal insulation property, and superhydrophilicity. Hence, this work provided a theoretical basis for improving the performance and expanding the application of silica aerogel.

Sintered and unsintered pressed fly ash geopolymer: A comprehensive study on structural transformation in nitric and sulfuric acid

Acidic attacks contribute to the degradation of cementitious materials, diminishing the structural service life and increasing the requirement for maintenance of the structure. To address the limited understanding of the impact of the sintering process on the acid resistance of pressed geopolymer, an investigation and comparison of the acid resistance of room-cured (RPG) and sintered (SPG) pressed geopolymer was performed. Specimens were immersed in 3 % and 8 % nitric (HNO3) and sulfuric (H2SO4) acids for 7 and 28 days. Despite the higher sorptivity, SPG demonstrated better mechanical strength retention than that of RPG. Specifically, the compressive strength of SPG after 3 % of HNO3 immersion for 28 days increased (+14.2 %), surpassing the control specimen, while RPG experienced a 14.5 % strength drop. The strength increment in SPG was due to the further geopolymerization during acid immersion. In RPG, a new crystalline phase of NaNO3 was observed after immersion in 8 % HNO3 for 28 days. In contrast, SPG showed no evidence of NaNO3 formation, indicating lower reactivity with HNO3 compared to RPG. Additionally, both RPG and SPG exhibited gypsum formation after immersion in H2SO4. The presence of gypsum induced crack formation in RPG, whereas SPG, with its intensive cross-linked structure, effectively compensated for gypsum expansion, preventing crack formation. This finding is crucial for practical applications where exposure to aggressive acids is a concern, as it provides a method to enhance the acid resistance of geopolymer structures.

External magnesium sulfate attack on hydrated Portland-limestone cements: Effect of the concurrent presence of sodium chloride in the corrosive environment and metakaolin admixture in the binder

Magnesium sulfate attack on Portland-limestone cement pastes at low temperature was investigated considering the concurrent presence of sodium chloride in the corrosive solution. The common deterioration mechanism, involving leaching of portlandite and C─(A─)S─H phase and formation of crystalline phases and amorphous cross-linked aluminosilicate structures, was mitigated in the pastes made from ordinary or Portland-limestone cements by increasing amounts of dissolved sodium chloride. Conversely, it was intensified in the blend with metakaolin by the additional decomposition of C─A─H phases with the formation of amorphous aluminate hydrate. The reduced cross-linking of the aluminosilicate structures is attributed to the structural association of sodium in the low-Ca/Si chains. C─A─H phase was also consumed in the heavily deteriorated cement paste with the highest limestone content. The mitigating effect of sodium chloride is proposed to be due to the corrosive environment's reduced acidity and the protective effect exerted by the sodium ions absorbed at the surface of aluminosilicate structures.

Preparation and thermal cycling performance of Ce-doped YSZ thermal barrier coatings by a novel cathode plasma electrolytic deposition

The preparation and realization of highly reliable thermal barrier coatings (TBCs) on the internal surface of complex cavities is a bottleneck problem. Traditional coating methods are difficult to deposit and fulfil service requirements. In this study, a novel structure of YSZ and Ce-doped YSZ (CeYSZ) TBCs was prepared by a newly cathode plasma electrolytic deposition (CPED) technology. The results suggested that both the CPED-YSZ and CPED-CeYSZ coatings exhibited porous cross-linked dendritic structures. Because Ce doping significantly improved the phase stability of tetragonal structure and enhanced thermal insulation temperature during a burner-rig test at 1300 °C, resulting in a threefold increase in the thermal cycling life of the CPED-CeYSZ coating compared to the CPED-YSZ coating. This work provided a new strategy for tailoring multiple rare-earth principal components of high-performance TBCs and depositing them on the inner surface of complex cavities with high aspect ratios.

The synthesis of high sinterability (Zr, Hf)C and SiC hybrid nanocrystalline particles by sol-gel method

Multi-phase UHTCs are favoured for their superior ablation resistance and mechanical properties. In this work, to improve the efficiency and decrease the sintering temperature and pressure, the (Zr, Hf)C and SiC hybrid nanocrystalline particles were prepared via the sol-gel method combining carbothermal reduction at 1600 °C. Utilizing their high sinterability, a relative density of 96.1% (Zr, Hf) C–SiC composite was obtained at the conditions of 1900 °C and 30 MPa using SPS technology. XPS and FT-IR results demonstrate that Zr, Hf, and Si were successfully trapped in the cross-linking structure of the precursors. Precursors of Zr, Hf, and Si reached a molecular-level mixture in the gel phase. SEM, XPS, and XRD characterization showed that the Si–C bond was formed preferentially, leading to the emergence of SiC whiskers and SiC wrapped (Zr, Hf)C with increasing temperature. And, the (Zr, Hf)C can be easily generated during solid solution reaction. Eventually, a nanoscale mixture of (Zr, Hf)C and SiC particles was successfully obtained at 1600 °C. The hardness and compressive strength of the (Zr, Hf)C–SiC composite were 12.94 GPa and 622 MPa, respectively. Comparing usual sintering processes (over 2000 °C and 35 MPa), the reason for the improved sinterability can be attributed to the high sintering activity of the (Zr, Hf)C and SiC hybrid particles, and the existence of the solid solution and nano-SiC.

Highly efficient thermal conductivity of polyarylene ether nitrile composites via the introduction of hybrid fillers and tailored cross-linked structure

Polymer dielectrics with high thermal conductivity (λ) and excellent insulating properties are of interest in miniaturized and integrated electronic devices. However, most polymers are unable to fulfill this need due to their inherent structure. In this work, a polymer alloy with balanced thermal conductive and dielectric properties was successfully prepared by polyarylene ether nitrile(PEN), bisphthalonitrile-microsphere@boron nitride nanosheets(Bm@BNNS), and silicon carbide whisker (SiCws) at different scales. Specifically, introduction of Bm@BNNS fillers with core-shell structure into PEN resins results in heterogeneous interfaces, which effectively reduces the agglomeration and dosage of BNNS and synergistically improves the λ and dielectric performance. Besides, it has high breakdown strength (Eb) and high energy storage density (242.26 kV/mm, 1.66J/cm3) when filled with only 4.37 vol% BNNS compared to pure PEN. Furthermore, effects of one-dimensional SiCws at different scales on formation of heat-conduction pathways and electrical insulation properties of PEN/Bm@BNNS composites were investigated. The findings display that PEN/Bm@BNNS/SiCws composites with large size SiCws (7.81 vol%) achieved a high λ of 2.376 W/m.K, which was 135.24 % and 87.09 % higher than pure PEN and PEN/Bm@BNNS composites, respectively. Thus, the thermal conductive pathways are constructed by line-plate structure (SiCws-BNNS), and insulating performance primarily on the core-shell structure (Bm@BNNS). Besides, the novel PEN/Bm@BNNS/SiCws hybrid materials are together with a low coefficient of thermal expansion of 38–89 ppm/°C and high Tg of 220 °C. Thus, it gives a promising insight to achieve highly λ polymer-based insulating film materials used for high-temperature-resistant fields.

The influence of multi-scale tough liquid fiber toughening agent on the mechanical properties of oil well cement-based composite materials

Cementing is a key process in drilling engineering, and the cement sheath in cementing can sometime have problems such as significant brittleness, low toughness, and low resistance to impact damage, especially in perforation and fracturing environments where the cement sheath is more susceptible to damage. In response to the above issues, three types of inorganic carbon fibers, including 1 mm carbon fiber, 2 mm carbon fiber, and nanocarbon fiber, were studied indoors to investigate the influence of their ratios on the mechanical properties of cement paste. The optimal mixture of 1 mm carbon fiber, 2 mm carbon fiber, and nanocarbon fiber in a ratio of 3:2:1 was selected, and a multi-scale liquid fiber toughening agent BS-54 was obtained through special liquefaction process treatment. The liquid fiber toughening agent BS-54 has good water dispersibility and can evenly disperse in the slurry water, effectively improving the dispersion and addition of multi-scale fibers in cement slurry. The cement slurry prepared with multi-scale dispersed liquid fiber toughening agent has good rheological properties, water loss, and thickening properties. The addition of multi-scale dispersed liquid fiber toughening agent to cement slurry significantly increases the tensile strength, impact strength, and compressive strength of cement paste, effectively reduces the elastic modulus of cement paste, improves the strength of cement paste, and achieves toughening effect. Microscopic analysis shows that the active nanoparticles dispersed by multi-scale dispersed liquid fiber toughening agents can interweave between gaps, and the dense cross-linked structure formed by their multi-scale micro nano structure improves the toughness and strength of cement slurry. Moreover, the multi-scale dispersed liquid fiber toughening agent cement slurry ensures that the cement stone sample has good integrity under external impact, which is conducive to improving the impact resistance of the cement stone.

Satisfactory Tensile Strength and Strain of Recyclable Polyurethane with a Trimaleimide Structure for Thermal Self-Healing and Anticorrosive Coatings.

Bismaleimide (BMI) is often used as the cross-linking reagent in Diels-Alder (D-A)-type intrinsic self-healing materials (DISMs) to promote the connectivity of damaged surfaces based on reversible D-A bond formation on the molecular scale. Until now, although DISMs have exhibited great potential in the applications of various sensors, electronic skin, and artificial muscles, it is still difficult to prepare DISMs with satisfactory self-healing abilities and high tensile strengths and strains at the same time, thus largely limiting their applications in self-healing anticorrosive coatings. Herein, symmetrical trimaleimide (TMI) was successfully synthesized, and trimaleimide-structured D-A self-healing polyurethane (TMI-DA-PU) was prepared via the reversible D-A reaction (cycloaddition of furan and maleimide). As a DISM, TMI-DA-PU exhibits apparently higher self-healing efficiency (98.7%), tensile strength (25.4 MPa), and strain (1378%) compared to bismaleimide-structured D-A self-healing polyurethane (BMI-DA-PU) (self-healing efficiency, 90.2%; tensile strength, 19.3 MPa; strain, 1174%). In addition, TMI-DA-PU shows a high recycling efficiency (>95%) after 4 cycles of recycling. A series of characterizations indicate that TMI provides more monoene rings as the self-healing sites, forms denser cross-linked structures compared to BMI, and is, thus, more appropriate to be used for DISM applications. Moreover, the barrier abilities of coatings can be semi-quantitatively expressed by the impedance value at 0.01 Hz (|Z|0.01Hz). The |Z|0.01 Hz value of the TMI-DA-PU coating is 3.93 × 109 Ω cm2 on day 0, which is significantly higher than that of the BMI-DA-PU coating (6.76 × 108 Ω cm2 on day 0), indicating that the denser rigid cross-linked structure of TMI results in the small porosity in the TMI-DA-PU coating, thus effectively improving the anticorrosion performance. The construction of DISMs with the structure of TMI demonstrates immense potential in self-healing anticorrosive coatings.

One-step of ionic liquid-assisted stabilization and dispersion: Exfoliated graphene and its applications in stimuli-responsive conductive hydrogels based on chitosan

Conductive hydrogels, as novel flexible biosensors, have demonstrated significant potential in areas such as soft robotics, electronic devices, and wearable technology. Graphene is a promising conductive material, but its dispersibility in aqueous solutions exists difficulties. Here, we discover that untreated graphene, after exfoliation by different ionic liquids, can disperse well in aqueous solutions. We investigate the impact of four ionic liquids with varying alkyl chain lengths ([Bmim]Cl, [Omim]Cl, [Dmim]Cl, [Hmim]Cl) on the dispersibility of grapheme, and a dual physically cross-linked network hydrogel structure is designed using acrylamide (AM), acrylic acid (AA), methyl methacrylate octadecyl ester (SMA), ionic liquid@graphene (ILs@GN), and chitosan (CS). Notably, SMA, CS, AA and AM act as dynamic cross-linking points through hydrophobic interactions and hydrogen bonding, playing a crucial role in energy dissipation. The resulting hydrogel exhibits outstanding stretchability (2250 %), remarkable toughness (1.53 MJ/m3) in tensile deformation performance, high compressive strength (1.13 MPa), rapid electrical responsiveness (response time ∼ 50 ms), high electrical conductivity (12.11 mS/cm), and excellent strain sensing capability (GF = 12.31, strain = 1000 %). These advantages make our composite hydrogel demonstrate high stability in extensive deformations, offering repeatability in pressure and strain and making it a promising candidate for multifunctional sensors and flexible electrodes.

Cellulose hydrogels with high response sensitivity and mechanical adaptability for flexible strain sensor and triboelectric nanogenerator

Cellulose hydrogels are widely regarded as green and environmentally friendly flexible electronic materials. Herein, a novel multiple cross-linked cellulose hydrogel (MCC/SA20/MCC-g-P(AA-co-AM-AMPS)) with high sensitivity (gauge factor = 440, 670 %, 60 ms) and good mechanical adaptability was designed and prepared. The prepolymer (MCC-g-P(AA-co-AM-AMPS)) was introduced into the microcrystalline cellulose/sodium alginate (MCC/SA) hydrogel network to form a multiple cross-linked network structure, which effectively enhanced the tension and elasticity of the cross-linked network, and improved the mechanical adaptability and sensitivity of the hydrogel. Additionally, it was assembled as a strain sensor that can accurately identify and monitor various motion states of the human body. It was also assembled as a friction nanogenerator (TENG) that continuously generates a stable open circuit voltage (7.2 V) for self-powering small electronic devices. This study provides an effective and feasible strategy for cellulose hydrogels in flexible sensors for sports health monitoring, sustainable green energy harvesting, and self-powering applications for small electronic devices.