Self-healing Poly Research Articles

Strong, Spontaneous, and Self-Healing Poly(Ionic Liquid) Elastomer Underwater Adhesive with Borate Ester Dynamic Crosslinking.

Adhesion in aqueous environments is often hindered by the water layer on the surface of the substrate due to the water sensitivity of the adhesive, greatly limiting the application environment. Here, a borate ester dynamically crosslinked poly(ionic liquid) elastomer adhesive (PIEA) with high strength, toughness, self-healing abilities, and ionic conductivity is synthesized by copolymerizing hydrophobic ionic liquid monomer ([HPVIm][TFSI]) and 2-methoxyethyl acrylate (MEA). The adhesion strength of PIEA can increase spontaneously from almost no adhesion to 314 kPa after 12 h without any external preloading due to the dissociation of the borate ester in water, leading to noncovalent interactions between the hydroxyl groups of PIEA and the substrate. Additionally, PIEA can be developed for soft sensors or ion electrodes to enable underwater detection and communication. This strategy offers broad application potential for the development of novel underwater smart adhesives.

Proposal for a New Method for Evaluating Polymer-Modified Bitumen Fatigue and Self-Restoration Performances Considering the Whole Damage Characteristic Curve

Fatigue performance and self-repairing activity of asphalt binders are two properties that highly influence the fatigue cracking response of asphalt pavement. There are still numerous gaps in knowledge to fill linked with these two characteristics. For instance, current parameters fail to accommodate these two bitumen phenomena fully. This study aims to propose a new procedure to address this issue utilizing the linear amplitude sweep (LAS) test, LAS with rest period (RP) (LASH) test, and simplified viscoelastic continuum damage (S-VECD) model. This research work used four different types of asphalt binders: neat asphalt (NA), self-healing thermoplastic polyurethane (STPU)-modified bitumen (STPB), self-healing poly (dimethyl siloxane) crosslinked with urea bond (IPA1w)-modified bitumen (IPAB), and styrene–butadiene–styrene (SBS)-modified bitumen (SBSB). Before the testing process, all the materials were subjected to short-term and long-term aging. The new procedure showed a superior capacity to analyze and accommodate all bitumen fatigue performances and self-repairing activities compared to the current method. Another finding proved that asphalt binders with a higher self-restoration behavior failed to show a better fatigue performance. Moreover, the higher fatigue performance increments produced by STPU and IPA1w in NA concerning the control bitumen were 123.7% and 143.7%, respectively. Those values were obtained with 1.0% STPU and 0.5% IPA1w in NA. A breakthrough finding demonstrated that asphalt binder fatigue response is augmented when the RP was applied at a higher damage intensity (S) value. STPB and IPAB reached their highest increments of fatigue response, containing 1.0% of STPU and 0.5% of IPA1w, respectively. Those augmentations were 207.54% and 232.64%, respectively.

Ultrarobust, Self-Healing Poly(urethane-urea) Elastomer with Superior Tensile Strength and Intrinsic Flame Retardancy Enabled by Coordination Cross-Linking.

Poly(urethane-urea) elastomers (PUUEs) have gained significant attention recently due to their growing demand in electronic skin, wearable electronic devices, and aerospace applications. The practical implementation of these elastomers necessitates many exceptional properties to ensure robust and safe utilization. However, achieving an optimal balance between high mechanical strength, good self-healing at moderate temperatures, and efficient flame retardancy for poly(urethane-urea) elastomers remains a formidable challenge. In this study, we incorporated metal coordination bonds and flame-retarding phosphinate groups into the design of poly(urethane-urea) simultaneously, resulting in a high-strength, self-healing, and flame-retardant elastomer, termed PNPU-2%Zn. Additional supramolecular cross-links and plasticizing effects of phosphinate-endowed PUUEs with relatively remarkable tensile strength (20.9 MPa), high elastic modulus (10.8 MPa), and exceptional self-healing efficiency (above 97%). Besides, PNPU-2%Zn possessed self-extinguishing characteristics with a limiting oxygen index (LOI) of 26.5%. Such an elastomer with superior properties can resist both mechanical fracture and fire hazards, providing insights into the development of robust and high-performance components for applications in wearable electronic devices.

Thiourea as a "Polar Hydrophobic" Hydrogen-Bonding Motif: Application to Highly Durable All-Underwater Adhesion.

Here, we report that, in contrast to urea, thiourea functions as a "polar hydrophobic" hydrogen-bonding motif. Although thiourea is more acidic than urea, thiourea exchanges its N-H protons with water at a rate that is 160 times slower than that for urea at 70 °C. This suggests that thiourea is much less hydrated than urea in an aqueous environment. What led us to this interesting principle was the serendipitous finding that self-healable poly(ether thiourea) adhered strongly to wet glass surfaces. This discovery enabled us to develop an exceptionally durable all-underwater adhesive that can maintain large adhesive strength for over a year even in seawater, simply by mechanically mixing three water-insoluble liquid components on target surfaces. Because thiourea is hydrophobic, its hydrogen-bonding networks within the adhesive structure and at the adhesive-target interface are presumed to be dehydrated. For comparison, a reference adhesive using urea as a representative "polar hydrophilic" hydrogen-bonding motif was durable for less than 4 days in water. Highly durable all-underwater adhesives are needed in various fields of marine engineering and biomedical sciences, but their development has been a major challenge because a hydration layer that spontaneously forms in water always inhibits adhesion.

Dynamics of Dipolar and Ionic Interactions in Self-Healable Poly(ionic liquid) Copolymers

Dynamics of Dipolar and Ionic Interactions in Self-Healable Poly(ionic liquid) Copolymers

Shear stiffening and magneto-induced properties of magnetorheological elastomer based on self-healing poly(urethane-urea) matrix

A novel multifunctional composite material, defined as self-healing magnetorheological elastomer (SH-MRE), which exhibits both shear stiffening and magnetorheological effects as well as self-healing ability, is obtained by dispersing carbonyl iron particles in a poly(urethane-urea) matrix. The dynamic shear properties are tested through oscillation frequency and magnetic field sweeps. When shear stress is applied with an excitation frequency of 0.1 Hz to 100 Hz, the storage modulus of the poly(urethane-urea) matrix increases sharply, showing a good shear stiffening effect. In addition to the magnetically dependent mechanical properties with a magnetic flux density of 0–0.894 T, the self-healing efficiency of the isotropic SH-MREs with destructive shear damage after healing can be influenced by the mass fraction of the carbonyl iron particles, the applied magnetic field strength and the support of trace solvents. Based on the experimental results, it is believed that the hydrogen bonds in the dynamic hard domains and the magnetic interaction forces between the carbonyl iron particles induced by the magnetic field are the cause of the good multifunctional properties.

Understanding neutron-shielding properties of self-healing poly(vinyl alcohol) hydrogels containing rare-earth oxides through simulations

This work assessed the theoretical neutron-shielding capabilities of autonomously self-healing poly(vinyl alcohol) (PVA) hydrogels containing rare-earth oxides, namely samarium oxide (Sm2O3), europium oxide (Eu2O3), and gadolinium oxide (Gd2O3), through PHITS and GEANT4 simulations. The assessment covered a range of filler contents (from 0 to 20 %wt in 4 %wt increments) and neutron energies (0.025 eV, 1 MeV, and 4 MeV). The determination showed that there was good agreement between the results from both simulations (average percentage difference of 0.39 %), with the thermal neutron-shielding properties of the hydrogels improving as the filler content increased, evidenced by the hydrogels containing 20 %wt of the fillers, especially those with Gd2O3, exhibiting the highest overall shielding properties. On the other hand, the deviations in the ability to attenuate fast neutrons (1 MeV and 4 MeV) with respect to filler contents were less pronounced than those for thermal neutrons. Additionally, the recommended filler contents for actual production were also determined by comparing the results in this work with those obtained from two common 5 wt% borated hydrogels. The comparison revealed that the recommended contents for Sm2O3, Eu2O3, and Gd2O3 were 9.8, 12.3, and 1.6 %wt, respectively, of which the smallest recommended content of Gd2O3 confirmed the superiority of Gd2O3 in thermal neutron attenuation. Lastly, the overall outcomes from this work suggested that PVA hydrogels, with the addition of rare-earth oxides as fillers, could serve as promising, effective neutron-shielding materials, with the added benefit of being self-healable that prolonged the lifetime of the developed shielding hydrogels as well as enhancing the safety of personnel.

Development of a Framework for Assessing Bitumen Fatigue Cracking Performance under Different Temperatures and Aging Conditions

A full understanding of bitumen fatigue cracking behavior is extremely important as this phenomenon has a considerable influence on bituminous pavement performance. The current framework for assessing this asphalt binder property is inconsistent in ranking bitumen fatigue performance in terms of the failure definition and damage characteristic curve (DCC) analysis. This study used four different types of asphalt binders: neat asphalt (NA), self-healing thermoplastic polyurethane (STP)-modified bitumen, self-healing poly (dimethyl siloxane) crosslinked with urea bond (IPA1w)-modified bitumen, and styrene–butadiene–styrene (SBS)-modified bitumen (SBSB). All the bitumens were subjected to short-term and long-term aging, and they were also tested by utilizing the linear amplitude sweep (LAS) test and the simplified viscoelastic continuum damage (S-VECD) model. LAS and S-VECD procedures were used to apply the newly proposed and current frameworks in order to analyze bitumen performance. The current framework showed that the bitumens that used a higher number of loading cycles (N) to reach their failure points (Nf) failed to exhibit greater fatigue performances in terms of DCC analysis. The developed framework (mainly based on the damage intensity [S] instead of N) was used to solve the inconsistency between the failure definition and DCC assessment in ranking bitumen performance. Additionally, the current framework (failure criterion) presented two R2 values below 0.1, but the developed framework (failure criterion) showed that all R2 values were greater than 0.9. The developed framework represents a turning point because, for the first time, this type of procedure is mainly being based on S instead of N. Although further tests are needed to confirm its efficiency, it eliminates the inconsistency between the failure definition and DCC assessment.

Comb-like poly(β-amino ester)-integrated PEO-based self-healing solid electrolytes for fast ion conduction in lithium-sulfur batteries.

All-solid-state lithium-sulfur batteries (ASSLSBs) using poly(ethylene oxide) (PEO) electrolytes offer significant advantages in energy density and safety. However, their development is hampered by the slow Li+ conduction in solid polymer electrolytes and sluggish electrochemical conversion at the cathode-electrolyte interface. Herein, we fabricate a self-healing poly(β-amino ester) with a comb-like topological structure and multiple functional groups, synthesized through a Michael addition strategy. This material modifies the PEO-based solid-state electrolyte, creating fast Li+ transport channels and improving polysulfides conversion kinetics at the electrode surface. Consequently, both modified all-solid-state lithium symmetric cells and lithium-sulfur batteries exhibit improved electrochemical performance. This work demonstrates an expanded interpenetrating macromolecular engineering approach to develop highly ion-conductive solid polymer electrolytes for ASSLSBs.

Self-Healable Poly(Acrylic Acid) Binder toward Optimized Electrochemical Performance for Silicon Anodes: Importance of Balanced Properties

Self-Healable Poly(Acrylic Acid) Binder toward Optimized Electrochemical Performance for Silicon Anodes: Importance of Balanced Properties

Harnessing Activated Alkyne-Hydroxyl “Click” Chemistry for Degradable and Self-Healing Poly(urea vinyl ether ester)s

Harnessing Activated Alkyne-Hydroxyl “Click” Chemistry for Degradable and Self-Healing Poly(urea vinyl ether ester)s

A self-healing poly(ionic liquid) block copolymer electrolyte enabled by synergetic dual ion-dipole interactions

Currently, there is a growing demand for self-healing solid polymer electrolytes (SPEs) with high performance for next-generation flexible electronics. Herein, self-healing SPEs (PIBCPEs) have been fabricated by doping poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in poly(ionic liquid) (PIL) block copolymers. The imidazole cations of the PIL blocks and the oxygen atoms in the poly(ethylene oxide) (PEO) blocks and the -CF3 dipoles in PVDF-HFP formed dual ion–dipole interactions, which not only endowed PIBCPEs with outstanding self-healing capability, but also facilitated lithium ion transport. Molecular dynamics (MD) simulation results exhibited rapid transport of lithium ions in the continuous phase formed by microphase separation. In addition, the electrostatic attraction of the imidazole cations to TFSI- increased lithium ion transference number. PIBCPEs also possessed excellent thermal stability, electrochemical oxidation stability, and good interfacial stability. Based on these advantages, the assembled LiFePO4/PIBCPE_27/Li cell exhibited a high discharge capacity at 0.5 C with capacity retention of 97.1 % after 250 cycles. Importantly, PIBCPEs could restore its ionic conductivity and cycling performance of cell after self-healing, showing a broad potential for applications in flexible and secure wearable device.

Nanodiamond reinforced self-healing and transparent poly(urethane–urea) protective coating for scratch resistance

ABSTRACT With increasing demand for scratch-resistant flexible electronics, the development of transparent coatings with good scratch resistance and self-healing properties has emerged as a key research topic. In this study, a high-strength self-healing poly(urethane – urea) (PUU)-based nanocomposite coating was prepared by introducing functionalized nanodiamond (ND) into a PUU matrix via solution blending. The PUU matrix had hard-segment repeating units and was constructed using isophorone diamine and isophorone isocyanate. The ND particles were modified using a silane coupling agent, 3-aminopropyltriethoxysilane, to obtain well-dispersed KH-ND nanoparticles. KH-ND promoted microphase separation in the PU matrix, inducing the formation of dense and homogeneous hard domains that dissipated stress, prevented further crack development, and improved the mechanical properties and scratch resistance of the coating. In addition, the coating exhibited excellent self-healing properties. Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were used to characterize the self-healing and hardening mechanisms of the coating. The environmentally friendly PUU/KH-ND coating is easy to prepare and has broad application prospects in transparent and anti-scratch coatings for flexible electronics, automobiles, and home appliances.

Self-healing poly(oxime–carbamate) films with tunable mechanical properties derived from rosin

Thermoset polymers with superior dimensional stability and creep resistance have been widely used in various electronic and energy devices. However, they are difficult to reprocess and recycle, and with the gradual decrease in nonrenewable resources, there is an urgent need for new sustainable materials as alternatives to thermoset polymers. Polymer materials with self-healing properties can provide high durability and sustainability for devices. In this work, we prepared a series of rosin-based poly(oxime–carbamate) films by reacting rosin acrylate/glycidyl methacrylate ester with toluene 2, 4-diisocyanate using dimethylglyoxime as the chain extender and triethanolamine as the crosslinking agent. The introduction of rosin with a rigid tricyclic phenanthrene structure in the prepared films resulted in excellent tensile strength (4.9 ± 0.03 MPa) while maintaining high elongation at break (973.2 % ± 4.8 %) and toughness (20.9 ± 0.1 MJ m−3). The good self-healing properties of the prepared films (90.6 % ± 1.5 %, 60 °C for 3 h) were attributed to the introduction of dynamic oxime–carbamate bonds. In particular, the tunable mechanical and self-healing properties of the films can be achieved by varying the molar ratio of rosin acrylate/glycidyl methacrylate ester to dimethylglyoxime. Furthermore, the prepared rosin-based films exhibited good adhesion, welding, and anticorrosion properties. Considering the reversible exchange mechanism of dynamic oxime–carbamate bonds and their use in self-healing and recycling applications, a new strategy for developing sustainable high-performance biobased self-healing coatings is presented.

Self-healing poly(acrylic acid) hydrogels fabricated by hydrogen bonding and Fe3+ ion cross-linking for cartilage tissue engineering

Self-healing poly(acrylic acid) hydrogels fabricated by hydrogen bonding and Fe3+ ion cross-linking for cartilage tissue engineering

Preparation and properties of multiple dynamically crosslinked self-healing poly(siloxane-urethane) flexible sensor

The flexible sensor with self-healing performance can heal itself when the sensor is damaged by the outside world, so it can significantly improve the service life of the sensor and reduce the repair cost, which has attracted widespread attention. However, currently, most flexible sensors with self-healing performance have problems such as single repair conditions and difficulty in balancing mechanical performance and repair efficiency. In this study, polypyrrole modified carbon nanotubes (PPY/CNTs) were first made, and then, inspired by the Chinese traditional myth “Nuwa Fuxi”, a multiple dynamic crosslinking self-healing composite poly(siloxane-urethane) conductive elastomer (CPUSi) was successfully developed. The prepared CPUSi has excellent mechanical properties (11.27 MPa) and total shear repair efficiency (84%) under the excitation of multiple dynamic reversible interactions. At the same time, the surface scratch of CPUSi can be self-healing under multiple conditions such as heating at 60 °C, infrared light and ultraviolet light. The scratch repair efficiency is up to 99.9% under infrared light for 2 h. in addition, CPUSi has cyclic response to temperature and strain, so the material has broad application prospects in sports monitoring, electronic skin, intelligent wear, brain-computer interface and other fields

Effect of halogenated hydrocarbon crosslinkers on self-healing poly(1,2,3-triazolium) adhesives

Poly(1,2,3-triazolium) (PTAM) is a kind of self-healing adhesive based on dynamic reversible covalent 1,2,3-triazolium, which is formed through the reaction of halogenated hydrocarbon and 1,2,3-triazole and plays an important role in the properties of PTAM. Therefore, it is valuable to understand the effect of halogenated hydrocarbon crosslinkers on the properties of PTAM. A series of PTAM adhesive with different crosslinkers have been prepared. The reactivity between halogenated hydrocarbon and 1,2,3-triazole was different. Crosslinkers with longer chain, iodine substituted and aromatic structure improved the adhesive property of PTAM adhesive joints, which was up to 17 MPa. The first self-healing efficiency of PTAM adhesive joints with aliphatic bromine crosslinkers reached more than 100% and the maximum cycle times of them was more than 9 before failure. The self-healing properties of PTAMs depend on the segment motion and anti-thermal oxygen aging of PTAMs. These results provide some insights for the structural design of self-healing adhesive and dynamic covalent materials.

Injectable, self-healing poly(amino acid)-hydrogel based on phenylboronate ester bond for osteochondral tissue engineering

A new generation of osteochondral integrated scaffolds is needed for articular osteochondral regeneration, which can not only facilitate the accurate construction of osteochondral scaffolds in a minimally invasive manner but also firmly combine the subchondral bone layer and cartilage layer. Herein, an osteochondral integrated hydrogel scaffold was constructed by the poly(L-glutamic acid) (PLGA) based self-healing hydrogels with phenylboronate ester (PBE) as the dynamic cross-linking. The bone layer self-healing hydrogel (hydrogel O-S) was prepared by physically blending nanohydroxyapatite into the self-healing hydrogel PLGA-PBE-S, which was fabricated by 3-aminophenylboronic acid/glycidyl methacrylate-modified PLGA (PLGA-GMA-PBA) and 3-amino-1,2-propanediol/N-(2-aminoethyl) acrylamide-modified PLGA (PLGA-ADE-AP). The cartilage layer self-healing hydrogel (hydrogel C-S) was prepared by PLGA-GMA-APBA and glucosamine- modified PLGA-ADE-AP (PLGA-ADE-AP-G). Excellent injectability and self-healing profiles of hydrogel O-S and C-S were observed, the self-healing efficiencies were 97.02% ± 1.06% and 99.06% ± 0.57%, respectively. Based on the injectability and spontaneous healing on the interfaces of hydrogel O-S and C-S, the osteochondral hydrogel (hydrogel OC) was conveniently constructed in a minimally invasive manner. In addition, in situ photocrosslinking was used to enhance the mechanical strength and stability of the osteochondral hydrogel. The osteochondral hydrogels exhibited good biodegradability and biocompatibility. The osteogenic differentiation genes BMP-2, ALPL, BGLAP and COL I of adipose-derived stem cells (ASCs) in the bone layer of the osteochondral hydrogel were significantly expressed, and the chondrogenic differentiation genes SOX9, aggrecan and COL II of ASCs in the cartilage layer of the osteochondral hydrogel were obviously upregulated after 14 d of induction. The osteochondral hydrogels could effectively promote repair of osteochondral defects after 3 months post-surgery.

Bilingual Bidirectional Stretchable Self-Healing Neuristors with Proprioception.

The coexistence and interaction of excitatory and inhibitory neurotransmitters at biological synapses enable bilingual communication, serving as a physiological foundation for organism adaptation, internal stability, and regulation of behavior and emotions in mammals. Neuromorphic electronics are expected to emulate the bilingual functions of the biological nervous system for artificial neurorobotics and neurorehabilitation. Here, we have proposed a bilingual bidirectional artificial neuristor array, which utilizes ion migration and electrostatic coupling properties between intrinsically stretchable and self-healing poly(urea-urethane) elastomer and carbon nanotube electrodes, realized by van der Waals integration. The neuristor exhibits depression or potentiation behaviors in response to the same stimulus in different operational phases and achieves a four-quadrant information-processing capability. These properties make it possible to simulate complex neuromorphic processes, which involve bilingual bidirectional responses, such as withdrawal or addiction responses, and array-based automated refresh. Furthermore, the neuristor array is a self-healing neuromorphic electronic device that can function effectively even under 50% mechanical strain and can recover operation voluntarily within 2 h after experiencing mechanical injury. Additionally, the bilingual bidirectional stretchable self-healing neuristor can emulate coordinated neural signal transmission from the motor cortex to muscles and integrate proprioception through strain modulation, similar to the biological muscle spindle. The properties, structure, operation mechanisms, and neurologically integrated functions of the proposed neuristor signify an advancement in neuromorphic electronics for next-generation neurorehabilitation and neurorobotics.

Preparation of multi band photothermal responsive bio-based superhydrophobic self-healing poly(siloxane-urethane) coating

In order to improve the poor hydrophobicity and single repair conditions of traditional self-healing polyurethane coatings, prepolymers were synthesized with bio-based polyol castor oil (CO), self-made alkyl aryl modified silicone polyols (Si-OH) and isophorone diisocyanate (IPDI), and 4,4'-dithiodianiline (ODD) was used as chain extender containing dynamic disulfide bond, 4-methylumbelliferone (4-MU), as a bio-based end capping agent with reversible ring structure, was polymerized step by step to prepare a photothermal responsive bio-based superhydrophobic self-healing poly(siloxane-urethane) coating (PUSi). In this paper, the effect of the amount of alkyl aryl modified silicone polyol (Si-OH) on the properties of PUSi was studied. The results showed that PUSi with different alkyl aryl modified silicone polyol additions could achieve self-healing under heating, UV irradiation and infrared light irradiation, and the maximum repair efficiency could reach 91% through optical microscope (OM), 3D profilometer and universal testing machine; The contact angle meter proved that the introduction of alkyl aryl modified silicone polyol greatly improved the hydrophobicity of PUSi, and the maximum water contact angle was 162°. The coating has broad application prospects in the fields of self-cleaning fabrics, super hydrophobic surfaces, special protective clothing and so on.