Dynamic Disulfide Bonds Research Articles

Laser-Infrared compatible stealth coating material with good mechanical properties and self-healing capability

A new type of laser-infrared compatible stealth coating material with good mechanical properties and self-healing capability was prepared in this research, and used the self-made hollow porous micro/nano-fiber structure Sn0.84Sm0.08Sb0.08O2 as the functional filler and polyurethane with dynamic disulfide bond as the binder. Results show that the coating material presented good mechanical properties and self-healing capability, with elongation being 710 %, tensile strength being 0.467 MPa and self-healing efficiency being 48.17 %. The coating material also presented good laser-infrared compatible stealth performance, with the infrared emissivity at wavelength of 3–5 μm and 8–14 μm being 0.568 and 0.687, respectively, and the reflectivity at wavelength of 1.06 μm and 1.54 μm being 1.26 % and 1.12 %, respectively.

Self-healing performance and rheological properties of styrene-butadiene-styrene block copolymer modified asphalt promoted by polyurea elastomers containing disulfide bonds

Self-healing asphalt is considered as one of the desirable methods to extend the service life of asphalt pavement. This research prepared a polyurea elastomer containing dynamic disulfide bonds (PUA)/styrene butadiene styrene block copolymer (SBS) composite modified asphalt. Moreover, a new asphalt self-healing performance evaluation method based on the damage process and results has been proposed. Subsequently, the self-healing ability of PUA, the distribution of modifier, the functional group and molecular weight of composite modified asphalt were characterized by fluorescence microscope, Fourier transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC). The self-healing potential and limits of PUA/SBS composite modified asphalt was investigated through the proposed healing linear amplitude scanning (HLAS) test. Results show that the SBS content and fatigue load level are the main factors affecting the self-healing promotion effect of PUA. The critical point of healing fatigue strain (HFS) can indirectly characterize the threshold at which healing promoters exert their effects. Next, the addition of fillers will reduce the self-healing performance of PUA/SBS composite modified asphalt, but it still improves by at least 61.318% compared with SBS modified asphalt. Finally, the addition of self-healing elastomers (PUA) improves the permanent deformation resistance at high temperature and low-temperature crack resistance of SBS modified asphalt. The dynamic recombination of disulfide bonds can increase the fatigue cycle number of 4%SBS modified asphalt by 93.52% at a 5% load strain level.

Preparation and Characterization of a Novel Self-Healing Polyurethane-Modified Asphalt Based on Dynamic Disulfide Bond

Preparation and Characterization of a Novel Self-Healing Polyurethane-Modified Asphalt Based on Dynamic Disulfide Bond

A hybrid reversible crosslinked polysiloxane elastomer with high toughness and recyclability

AbstractThe preparation of polysiloxane elastomers with outstanding mechanical properties, self‐healing capabilities, and high recyclability remains a formidable challenge despite their promising application prospects in flexible electronic devices. Herein, the polysiloxane elastomer is fortified with a hybrid reversible crosslinked network, incorporating Diels‐Alder (D‐A) and disulfide bonds for chemical crosslinking, as well as multiple hydrogen bonds for physical crosslinking, to effectively address this challenge. The presence of D‐A covalent bonds not only enhances the stability of the polymer network but also facilitates the reconstruction of dynamic disulfide and hydrogen bonds as sacrificial bonds for dissipating energy. This design further enhances the toughness of the obtained elastomer while simultaneously providing self‐healing capabilities and recyclability. Specially, relying on the hybrid reversible crosslinked network, the resulting polysiloxane elastomer PDMS3‐IPDI4‐SS‐F‐M demonstrates exceptional mechanical performance, boasting a toughness of 13.6 MJ/m3. Moreover, it exhibits commendable self‐healing ability with a self‐healing efficiency of 92% at 65°C for 24 h, as well as high thermal stability and recyclability without necessitating chemical treatment for polymer chain decomposition. The elastomer exhibits promising prospects for application in sustainable flexible support materials.

Ultra-wide damping temperature range polyurethane elastomer enabled by an asymmetrically structured chain extender with double disulfide bonds

Conventional polymer damping materials are extensively utilized to mitigate vibration and noise in various fields, yet suffer from the drawback of a narrow effective damping temperature range. Herein, we innovatively synthesized an asymmetrically structured chain extender (AIS) with double disulfide bonds that provided polyurethane elastomer (PUE) with ultra-high energy dissipation over a wide temperature range, which was unattainable by conventional chain extenders. This was achieved by enhancing the bond exchange rate of dynamic disulfide bonds in the PUE. Specifically, the asymmetric structure of AIS was strategically designed to disrupt the regularity of the hard segments of the PUE, enabling the disulfide bonds to break and reorganize efficiently, thus depleting mechanical energy. The results demonstrated that the effective damping temperature range (Tan δ > 0.3) of the PUE cured by AIS can reach 130 °C (−15 °C–115 °C), which is 210 % higher than that of the matrix, and a stable damping plateau was observed in the region from room temperature to high temperature. Moreover, the introduction of AIS significantly enhanced the mechanical properties of the PUE. This study encourages further investigation and application of disulfide bonds in the field of damping.

A multi-functional polyurethane elastomer with high damping, water resistance and flame retardancy

Polyurethane elastomer has become a current focal point in the field of damping materials due to superior comprehensive properties. However, its effective damping temperature range is limited, and existing methods often lead to a reduction in mechanical performance. Moreover, polyurethane exhibits poor water resistance and flame resistance, constraining its applications. In this study, we introduce a small amount of dangling chain and aromatic dynamic disulfide bond into polyurethane to achieve a balance between damping and mechanical performance. Notably, the fluorinated dangling chain improves water resistance of the material synchronously and effectively. Additionally, ammonium polyphosphate modified by melamine and diethyl bis(2-hydroxyethyl)aminomethylphosphonate are introduced into polyurethane to improve flame resistance. The prepared polyurethane elastomer exhibits excellent comprehensive performance, featuring an effective damping (tanδ≥0.3) temperature range of 153.2 °C (−53.2 °C ∼ 100 °C), V-0 level flame resistance and excellent water resistance. Meanwhile, the heat stability of the polyurethane elastomer has been significantly enhanced, while maintaining a certain level of mechanical performance (9.72 ± 0.25 MPa, 602.4 ± 30.1%). These improvements extend the service life of polyurethane and expand its range of potential applications.

Rheological properties and aging resistance of self‐healing polyurea elastomer modified asphalt

AbstractPolymer modified asphalt containing dynamic chemical bonds has the potential to increase the service life of asphalt pavement due to its excellent self‐healing ability. The effect of this self‐healing accelerator with dynamic chemical bond on the rheological properties and aging resistance of asphalt binder is still unclear. In this study, a self‐healing polyurea elastomer (PUA) modified asphalt containing dynamic disulfide bonds was prepared. The high‐ and low‐temperature performance and fatigue resistance of PUA modified asphalt were studied through multiple stress creep, low‐temperature bending beam rheometer, mechanical glass transition temperature, and linear amplitude scanning tests. Moreover, considering the service environment of asphalt over a wide temperature range (−30–70°C), three rheological aging indices (RAI) were proposed. At the same time, the aging resistance of PUA modified asphalt was evaluated by chemical aging index (CAI) based on carbonyl and sulfoxide groups. Finally, a linear relationship is established between RAI and CAI over a wide temperature range. The experimental results show that self‐healing accelerators can increase the resistance to permanent deformation of asphalt by 47.41% and the fatigue resistance by 88.54%. The S value of PUA modified asphalt decreased by at most 33.21% and the m value increased by at most 35.23% compared with BA at −18°C. Moreover, PUA can improve the long‐term thermal oxygen aging resistance of asphalt binders by at least 38.33% over a wide temperature range.Highlights Rheological properties of self‐healing polyurea elastomer modified asphalt. Aging resistance of self‐healing polyurea elastomer modified asphalt. Proposed rheological aging indices for different temperature ranges. Clarified the correlation between chemical–rheological aging indices.

Easily recycled thiol-ene elastomers with controlled creep

Starting from in-house synthesized allylic monomers containing dynamic disulfide (SS) bonds, a set of vitrimeric thiol-ene elastomers were prepared and characterized with respect to their viscoelastic and tensile properties. A mixture of a disulfide-containing diallyl monomer and disulfide-free diallyl, namely diallyl phthalate, was combined stoichiometrically with a thiol crosslinker, trimethylolpropane tris (3-mercaptopropionate), to obtain soft thiol-ene thermosets with varying degrees of dynamic bond content. The materials were able to relax strain induced stress completely and rapidly at moderately high temperatures when the disulfide content was above a certain threshold, which was accurately predicted by a statistically-based network (de)crosslinking model. Relaxation of materials with disulfide content below this threshold required the activation of an additional transesterification bond exchange process by increasing the temperature. Recycling of the materials could be achieved by hot-press molding at convenient temperatures. Especially in low-disulfide containing materials, changes were observed in the material structure and properties with increasing number of reprocessing cycles. However, a significant reduction in ambient temperature creep was observed upon reducing the disulfide content. The disulfide content can be easily optimized to yield minimal loss of mechanical property and minimal creep. This work opens up new avenues for the cost-effective development of vitrimeric elastomers with minimal ambient temperature creep.

An Intrinsic Self-Healable, Anti-Freezable and Ionically Conductive Hydrogel for Soft Ionotronics Induced by Imidazolyl Cross-Linker Molecules Anchored with Dynamic Disulfide Bonds.

Hydrogels are ideal materials for flexible electronic devices based on their smooth ion channels and considerable mechanical flexibility. A substantial volume of aqueous solution is required to enable the smooth flow of ions, resulting in the agony of low-temperature freezing; besides, long-term exposure to bending/tensile tress triggers fatigue issues. Therefore, it is a great challenge to prepare hydrogels with both freeze-resistance and long-term durability. Herein, a polyacrylic acid-based hydrogel with both hydrophobic interaction and dynamic reversible covalent bonding cross-linking networks is preparing (DC-hydrogel) by polymerizing a bi-functional imidazole-type ionic liquid monomer with integrated disulfide and alkene bonds (DS/DB-IL) and an octadecyl methacrylate, achieving self-healing. The DS/DB-IL anchored into the polymer backbone has a high affinity with water, reducing the freezing point of water, while the DS/DB-IL with free ions provides superior ionic conductivity to the DC-hydrogel. The polyacrylic acid with abundant carboxyl gives hydrogel good self-adhesiveness to different substrates. Ionotronics with resistance-type sensors with stable output performance are fabricated and explored its application to joint motion and health information. Moreover, hydrogel-based sensing arrays with high resolution and accuracy are fabricated to identify 2D distribution of stress. The hydrogels have great promise for various ionotronics in many fields.

Reconfigurable and orthogonal stiffness‐structure patterning of dynamically crosslinked amphigels

AbstractPatterning diversified properties and surface structure of polymer materials are of great importance toward their potential in biology, optics, and electronics. However, achieving both the patternability of stiffness and microstructure in a reconfigurable manner remains challenging. Here, we prepare amphigels crosslinked by dynamic disulfide bonds, which can be reversibly swollen by immiscible water or liquid paraffin. In the paraffingel form, the materials exhibited a high modulus of 130 MPa due to densified hydrogen bonds. Whereas swollen by water, the modulus fell over two orders of magnitude owing to the destruction of the hydrogen bonds. Via regionalized swelling of the solvents, well‐controlled and rewritable soft/stiff mechanical patterns can be created. On the other hand, the dynamic exchange of the disulfide crosslinking enables mechanophoto patterning to fabricate sophisticated macrogeometries and microstructures. The reconfigurable stiffness‐structure patterning can be manipulated orthogonally, which will create more application opportunities beyond conventional hydrogels and organogels.

Biological applications of lipoic acid-based polymers: an old material with new promise.

Lipoic acid (LA) is a versatile antioxidant that has been used in the treatment of various oxidation-reduction diseases over the past 70 years. Owing to its large five-membered ring tension, the dynamic disulfide bond of LA is highly active, enabling the formation of poly(lipoic acid) (PLA) via ring-opening polymerization (ROP). Herein, we first summarize disulfide-mediated ROP polymerization strategies, providing basic routes for designing and preparing PLA-based materials. PLA, as a biologically derived, low toxic, and easily modified material, possesses dynamic disulfide bonds and universal non-covalent carboxyl groups. We also shed light on the biomedical applications of PLA-based materials based on their biological and structural features and further divide recent works into six categories: antibacterial, anti-inflammation, anticancer, adhesive, flexible electronics, and 3D-printed tissue scaffolds. Finally, the challenges and future prospects associated with the biomedical applications of PLA are discussed.

The novel disulfide-containing diols synthesis and applied in self-healing fluorescent polyurethane elastomers

Polyurethane elastomers with repair abilities and robust mechanical properties remain a great challenge under mild conditions. Numerous studies have shown that dynamic disulfide bonds are the important chemical chain unit...

Self-healing polyacrylates based on dynamic disulfide and quadruple hydrogen bonds.

Herein, a self-healing polyacrylate system was successfully prepared by introducing crosslinking agents containing disulfide bonds and monomers capable of forming quadruple hydrogen bonds through free radical copolymerization. This polymer material exhibited good toughness and self-healing properties through chemical and physical dual dynamic networks while maintaining excellent mechanical properties, which expanded the development path of self-healing acrylate materials. Compared to uncrosslinked and single dynamically crosslinked polymers, its elongation at break was as high as 437%, and its tensile strength was 5.48 MPa. Due to the presence of dual reversible dynamic bonds in the copolymer system, good self-healing was also achieved at 60 °C. In addition, differential scanning calorimetry and thermogravimetric analysis measurements confirmed that the thermal stability and glass transition temperature of the material were improved owing to the presence of physical and chemical cross-linking networks.

GO-tagged PEI sizing agent imparts self-healing and excellent mechanical properties to carbon fiber reinforced epoxy laminates.

Carbon fiber-reinforced epoxy (CFRE) laminates have attracted significant attention as a structural material specifically in the aerospace industry. In recent times, various strategies have been developed to modify the carbon fiber (CF) surface as the interface between the epoxy matrix and CFs plays a pivotal role in determining the overall performance of CFRE laminates. In the present work, graphene oxide (GO) was used to tag a polyetherimide (PEI, termed BA) containing exchangeable bonds and was employed as a sizing agent to improve the interfacial adhesion between CFs and epoxy. This unique GO-tagged-BA sizing agent termed BAGO significantly enhanced the mechanical properties of CFRE laminates by promoting stronger interactions between CFs and the epoxy matrix. The successful synthesis of BAGO was verified by Fourier-transform infrared spectroscopy. Additionally, the partial reduction of GO owing to this tagging with BA was further confirmed by X-ray diffraction and Raman spectroscopy, and the thermal stability of this unique sizing agent was evaluated using thermogravimetric analysis. The amount of GO in BAGO was optimized as 0.25 wt% of BA termed 0.25-BAGO. The 0.25-BAGO sizing agent resulted in a significant increase in surface roughness, from 15 nm to 140 nm, and surface energy, from 13.2 to 34.7 mN m-1 of CF. The laminates prepared from 0.25-BAGO exhibited a remarkable 40% increase in flexural strength (FS) and a 35% increase in interlaminar shear strength (ILSS) due to interfacial strengthening between epoxy and CFs. In addition, these laminates exhibited a self-healing efficiency of 51% in ILSS due to the presence of dynamic disulfide bonds in BAGO. Interestingly, the laminates with 0.25-BAGO exhibited enhanced Joule heating and enhanced deicing, though the EMI shielding efficiency slightly declined.

Construction of durable antibacterial cellulose textiles through grafting dynamic disulfide-containing amino-compound and nanosilver deposition

Cotton textile is very comfortable to wear, and also provides an ideal environment for bacterial propagation, easily causing harm to human health. In order to address this issue, various antibacterial techniques are employed for cotton finishing. However, some processes are complex and involve the use of environmentally unfriendly chemicals. In this work, a durable and efficient antibacterial cotton fabric was prepared via grafting of an amino-compound containing dynamic disulfide bonds, and then in-situ deposition of silver nanoparticles (AgNPs). Briefly, the reactive α-lipoic acid-modified polyethyleneimine (mPEI) was introduced to the cotton fibers via thiol-ene click reaction. Subsequently, the amino groups and dynamically-generated sulfhydryl groups in the mPEI molecules were used to initiate the ultrafast reduction of silver ions without the participation of additional reductant, constructing a stable antibacterial layer on fiber surface. The results reveal that the amino and thiol groups of mPEI could form coordination bonds with the deposited silver nanoparticles, and the antibacterial ability of AgNP@cotton-g-mPEI fabric remains at a high level even after 20 washing cycles. After 30 min of contact with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the antibacterial rates against both bacteria reached 99.99 %. Meanwhile, the network matrix constructed by the recombination of the dynamic disulfide bonds in mPEI endows the cotton fabric with detectable wrinkle resistance and encouraging anti-ultraviolet effect. The present work provides a novel alternative for preparation of durable and efficient antibacterial textiles.

Construction and mechanism of phase-locked structured PU elastomers with tunable mechanical and self-healing properties

Self-healing elastomers with great mechanical properties have attracted much attention, however how to balance the mechanical property and self-healing performance is still challenging. In this work, we prepared polyurethane elastomers (PU-n) with different phase-locked structures in which dynamic disulfide bonds and hydrogen bonds are locked at low temperature to provide great mechanical strength and activated by heating to promote self-healing. PU-n exhibit tensile strength from 0.83 MPa to 11.98 MPa because of different microphase separation structures, which is attributed to different thermodynamic compatibility and hydrogen bonds between hard segment with different lengths and soft segment. PU-n can repair surface scratches within 10 min and the well-designed elastomer (PU-50) can achieve a full-cut self-healing efficiency above 90 % at 60 ℃ for 2 h. The self-healing process is dependent on the dynamic recombination of hydrogen bonds and disulfide bonds, which can be accelerated by heating because of the faster molecular motion. The dynamics characteristics of hydrogen bonds and disulfide bonds also endows PU-n with the recyclability, the recycled elastomer exhibits similar mechanical and self-healing properties with original elastomer. This work provides an effective strategy to achieve self-healing polyurethanes with the high mechanical strength.

Investigation on self-healing polyurethane coating doped with lignin composites for protecting cementitious materials

Surface protective coatings are prone to cracking and failure due to the deformation of concrete structure itself and harsh service environment factors such as UV, ion erosion, and large temperature differences during the period of service. It is urgently required to develop new types of self-healing coatings to provide long-lasting protection for concrete structures and extend their service life. In this investigation, a lignin-based self-healing agent was prepared using aniline and lignin as raw materials. Its characterization was analyzed by SEM and FT-IR. By introducing the lignin-based healing agent and dynamic disulfide bonds, a new kind of self-healing polyurethane coating was prepared, and its self-healing ability was qualitatively and quantitatively evaluated, indicating that it had excellent self-healing performance. After self-healing process, the crack could withstand bending force. Moreover, with the increased temperature, the self-healing efficiency of tensile strength gradually increased, reaching a maximum of 86.42% at 60 ℃. Meanwhile, the self-healing efficiency of its elongation at break firstly increased and then gradually decreased, reaching a maximum of 93.77% at 40 ℃. This self-healing polyurethane coating had high hydrophobicity (139.4°) and excellent abrasion resistance. After 40 friction cycles, its hydrophobicity only decreased by 10.9% to 124.2°. In addition, this self-healing protective coating also showed excellent resistance to chloride ions, effectively protecting cementitious materials with the damaged surface. This work provides a new method for long-term protection of concrete structures.

Photo-cured phase change energy storage material with photo-thermal conversion, self-cleaning and electromagnetic shielding performances via the lamellar structure strengthened by segment rearrangement of dynamic disulfide bond

At present, phase change materials (PCMs) with single function hardly meet the needs of advanced intelligent materials in practical applications, and the multifunction integration is the current trend. However, photo-cured multifunctional PCMs are hampered by insufficient transparency due to adding functional fillers, such as carbon and metal materials. The novel strategy is necessary to overcome this limitation. Here, a photo-cured multifunctional PCM is prepared by using the design of a lamellar structure composing the photo-cured phase change polymer layer and the functional fillers layer. The curing of the phase change polymer is realized by the photo-induced "thiol-ene" click reaction, and reversible dynamic disulfide bonds are introduced into the PCM, which not only gives the phase change crosslinked network reprocessability, but also strengthens the interface layer by the chain rearrangement to form a stable composite structure. The carboxylated multiwalled carbon nanotubes (CCNTs) and silver nanowires (AgNWs), as functional fillers, give the PCM photo-thermal conversion, self-cleaning and electromagnetic shielding (EMI SE) performances. Its phase change latent heat and photo-thermal conversion can reach 105.2 J/g and 78.5%, and the water contact angle is 142° with self-cleaning performance. In addition, due to the dense and well-developed conductive path formed by AgNWs layer on the PCM surface, the EMI SE effect can reach 39 dB with only 6.3% (in mass) filler content and 7.2% phase change latent heat loss. As far as we know, this is the first report about photo-cured PCMs with self-cleaning, photo-thermal conversion and EMI SE performances.

Preparation and Performance Study of Polyurethane/Epoxy Resin Interpenetrating Networks with Self‐Healing, Shape Memory, and High Damping Properties

AbstractInterpenetrating polymer networks (IPNs) possessing a wide damping temperature range are commonly employed as damping materials that are applied in numerous fields. But IPNs will gradually appear to fatigue microcracks and fracture when long‐term in the energy absorption and dissipation. So, the ability for IPNs to recover from damage is necessary that can considerably prolong their service life. Based on polyurethane elastomer and cross‐linked epoxy, several innovative self‐healing IPNs are designed and prepared in this research. The IPNs containing dynamic disulfide bond exhibit favorable damping and self‐healing properties. In detail, the loss factor of IPN‐80/20 is beyond 0.3 at temperatures between −0.8 and 65.5 °C that covers the operating temperature range at room temperature. What is more, The PU/EP IPNs also have excellent shape memory properties, self‐healing ability, and thermal stability.

Reprocessing and reconfigurable shape recovery of epoxy and Fe3O4 nanocomposites enabled by crosslinking with a polymeric hardener bearing disulfide bonds

In this contribution, we reported the preparation of the nanocomposites of epoxy with Fe3O4 with poly(α-lipoic acid) (PLA) as a polymeric crosslinker. It was found that the surface reaction between Fe3O4 nanoparticles and the macromolecular crosslinker significantly facilitated the fine dispersion of the inorganic nanoparticles. In the meantime, dynamic disulfide bonds were successfully introduced into the nanocomposites. Therefore, the nanocomposites displayed the excellent reprocessing (recycling) properties. In addition, the nanocomposites had the shape memory properties; the original shapes of the shape memory nanocomposites can be reprogrammed via the exchange of dynamic disulfide bonds. Owing to the incorporation of Fe3O4 nanoparticles, the nanocomposites possessed the excellent paramagnetic and photothermal properties. Furthermore, the photothermal properties can be utilized to trigger the shape recovery in a non-contact fashion.