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In this paper, a hydraulic soft gripper for underwater applications is designed to provide a solution for improving the gripping force as well as the sensing capability of the soft gripper. The soft gripper is made of silicone and has an integrated semi-circular hydraulic network inside. To enhance the rigidity and grasping performance of the soft gripper, we have integrated a restriction layer consisting of a spring steel plate in the soft gripper. Meanwhile, to enhance the sensing capability of this soft gripper, we have designed a water pressure sensor based on resistance strain gauges and integrated it on the spring steel plate. Before fabrication, we determined the structural parameters of the soft gripper by geometric analysis. Then we experimentally evaluated its pressure-bearing capacity, bending performance, the role of spring steel plates, and the accuracy of the sensor.The experimental results show that the spring steel plate improves the gripping force of the soft gripper, the sensor also has high accuracy, and the built four-finger gripping system has good adaptability to objects of different shapes and weights.Compared with the existing solutions, this solution takes a simpler structural form while improving the gripping force and sensing ability of the soft gripper, and integrates the issues of improving the gripping force and sensing ability. The spring steel plate used in this paper not only improves the gripping force of the soft gripper but also provides a stable and reliable platform for installing sensors.

TC3 cations loaded on hyaluronic acid were selectively taken up by cancer cells. The following incubation with A5 or A10 anions led to the bioorthogonal self-assembly of C3–A5/A10 in cancer cells with luminescence and singlet oxygen turn-on.

BSA@Fe/Ru nanoparticles with photocatalytic supplement of H2O2 and hydroxyl radical production at a neutral pH are developed, which display efficient and selective chemodynamic therapy (CDT) activity both in vitro and in vivo.

Hybrid MXene/reduced graphene oxide aerogel microspheres (MXene/rGOAMs),where MXenes are two-dimensional (2D) transition metal carbides, with abundant macro/meso/micro multi-scale pores and self-supporting structure, are prepared by electrospraying followed by freeze-drying and then thermal annealing. A center-diverging structure with well-aligned microchannels is formed within each microsphere, which can be maintained after thermal reduction. Such highly ordered 3D hybrid mesoporous network has been tested for the hydrogen evolution reaction (HER) because it may prevent the stacking of the 2D layers, thus enhancing the mass transfer. Actually, in the case of Ti3C2Tx/rGOAMs, obtained with an optimized MXene:GO mass ratio and after a thermal treatment at 400 °C, a better HER performance with respect to the bulk Ti3C2Tx aerogel or the MXene/GO composite is observed (η10=-336 mV), suggesting an accelerated mass transfer through different inter-sheets when the 3D mesoporous microsphere networks are created. The Ti3C2Tx/rGOAMs also exhibit enhanced HER activity compared to rGOAMs, suggesting that the MXene plays a key role due to the presence of titanium atoms with a low valence state.

Rutin is a naturally active compound with biological and medical value. The traditional extraction and separation method not only destroys the structure and activity of rutin, but results in a low extraction rate. In this work, the magnetic micellar molecularly imprinted polymer of rutin with a selective recognition function, i.e., RMMMIP was synthesized from 4 to Vinylphenylboron acid and 4-Vinylpyridine as functional monomer, derivatives of cholic acid as amphiphilic molecules. The internal hydrophobic and external hydrophilic characteristics of micelle was used to weaken the solvation of rutin and strengthen the non-covalent interaction between functional monomer and rutin. Fe

Designing hydrogels with both excellent mechanical properties and self-healing ability has attracted significant attention because the applications of hydrogels are restricted in many fields due to their poor mechanical properties and short service life. Herein, a novel type of hierarchically reversible crosslinked hydrogel was designed and fabricated using a poly(vinyl alcohol)–borax (PVA/borax) hydrogel and poly(1-allyl-2-thiourea-co-acrylamide) (P(ATU-co-AM)), where P(ATU-co-AM) was interpenetrated in the PVA/borax network to form a semi-interpenetrating network (semi-IPN). The PVA crystalline domains generated from the freezing–thawing process served as second crosslinking points in the semi-IPN structure, further enhancing the mechanical properties of hydrogels. The obtained hydrogels exhibited excellent mechanical properties (tensile strength of 3.6 MPa), rapid self-healing procedure (10 min), high healing efficiency (over 90%), agile pH-driven shape memory behavior (recovered within 260 s) and Ca2+-driven shape memory behavior, which are attributed to the reversible backbones imposed by the dynamic borate bonds, abundant hydrogen bonds from PVA and P(ATU-co-AM) chains, and crystallinity of PVA through freezing–thawing cycles. Taking advantage of these fabulous performances and inspired by the bending behavior of Mimosa, a soft catcher actuator was constructed as an example to illustrate the practical applications of this hydrogel, which could catch a plastic fish in Ca2+ solution. Thus, due to the self-healing property, actuators with complicated architectures and excellent shape memory behavior can be fabricated by assembling different double layer hydrogels. This study provides a novel strategy to prepare robust hydrogels without sacrificing their self-healing ability and mechanical properties, hopefully promoting the research on robust self-healing hydrogels.

A formidable scientific challenge for the development of self-healing polymers is how to rationally design molecular architectures that could integrate both highly efficient healing functions and excellent mechanical performances. Here, we present a novel rigid and tough but more healable polymer network enabled by self-catalytic cooperative multiple dynamic moieties (CMDMs) containing metal–ligand coordinations, multiple hydrogen bonds and reversible urea bonds. The strength and toughness of the materials are improved significantly via strong supramolecular interactions of CMDMs, resulting in a modulus, tensile strength and toughness up to 797.4 MPa, 73.6 MPa and 218.2 MJ m−3, respectively. The metal–ligand coordinations of CMDMs facilitate the dynamic exchange reactions between the urea bonds of CMDMs through a self-catalytic mechanism, providing the material with a much higher healing efficiency of 90% compared with 48% for the control sample without metal–ligand coordinations. CMDMs provide a novel paradigm for designing robust healable materials by integrating dynamic covalent bonds and supramolecular interactions into one single moiety.

Self-healing and recycling of fiber reinforced polymer (FRP) composites are of great significance towards pursuing a sustainable and circular economy, but remain a huge challenge due to the infusible and insoluble properties of thermoset polymers. The newly developed dynamic covalent polymers provide a great opportunity to resolve this issue for FRPs. Here we developed a novel type of dynamic covalently cross-linked polyacylsemicarbazide exhibiting a high modulus and self-healing/recycling capability due to the reversible properties of the dynamic acylsemicarbazide (ASC) moieties. Introducing different ASC moieties composed of different dihydrazides into the polymer can dramatically tune the mechanical, self-healing and reprocessing properties. An optimized polyacylsemicarbazide with a Young's modulus of ∼2.84 GPa, a stress at break of ∼100 MPa and a glass transition temperature of ∼123 °C exhibits a self-healing efficiency of ∼94.4% and great reprocessing properties. Furthermore, using this newly developed PASC material as the matrix resin, the carbon fiber reinforced polymer composite was successfully prepared through solution impregnation and thermal pressing. The composite exhibits an interlaminar shear strength of 40 MPa and a healing efficiency of 76.2%. The great dynamic reversible properties of ASC moieties enables the recycling of the carbon fiber and matrix resin, respectively, from the composites by a solvolysis method.

It is often unavoidable that automotive steel sheet parts might undergo plastic deformation during forming and service life. The present research explored the effect of pre-strain up to 15% on hydrogen embrittlement (HE) behavior of a cold-rolled and intercritically annealed Al-containing medium-Mn steel by electrochemical hydrogen charging and permeation testing, thermal hydrogen desorption spectrometry and slow strain rate tensile testing. The results show that the primary microstructural changes after pre-strain are the significant increase in dislocation density and the transformation of a slight part of retained austenite into martensite, which cause a decrease in hydrogen diffusion coefficient and a significant increase in absorbed reversible hydrogen concentration. Therefore, the HE susceptibility increases notably with an increase in pre-strain. It is thus concluded that pre-straining not only enhance the strength level but also remarkably increase the HE susceptibility of medium-Mn steel.

To obtain a refined and homogenized microstructure as well as enhanced combination of strength and toughness, the influence of controlled forging on the microstructure and mechanical properties of a Mn–Cr-type bainitic forging steel microalloyed with V + Ti elements was explored. Microstructural characterization shows that the final microstructure of the as-forged steel changed from primarily granular bainite (GB) to primarily lower lath-bainite (LLB) through controlled forging of mainly finish-forging temperature and post-forging cooling rate. The result of physical–chemical phase analysis shows that almost all the added Ti is in the (V,Ti)(C,N) precipitates, while only ~ 7% of the added V is in the precipitates, and there is only a slight increase in the amount of the (V,Ti)(C,N) precipitates with changing forging condition, and their precipitation strengthening is ~ 40 MPa. The tensile properties except the total elongation increase significantly from the GB sample to the LLB sample, and the latter exhibits identical or even higher mechanical properties than conventional quenched and tempered 42CrMo steel except the yield strength. Instrumental impact tests revealed that the crack initiation energy, propagation energy and the ability of arresting crack growth of the LLB sample are significantly higher than those of the GB sample. The reduction and/or even elimination of large blocky M/A, the increase in high-angle boundaries fraction and microstructure refinement are primarily responsible for this enhancement of doubled impact toughness. It is thus suggested that suitable controlled forging is a promising strategy to regulate and control the microstructure and mechanical properties of bainitic forging steel.

A new procedure for ultrasonication-induced atom transfer radical polymerization (sono-ATRP) in aqueous media was developed. Polymerizations of oligo(ethylene oxide) methyl ether methacrylate (OEOMA) and 2-hydroxyethyl acrylate (HEA) in water were successfully carried out in the presence of ppm amounts of CuBr2 catalyst and tris(2-pyridylmethyl)amine ligand when exposed to ultrasonication (40 kHz, 110 W) at room temperature. Aqueous sono-ATRP enabled polymerization of water-soluble monomers with excellent control over the molecular weight, dispersity, and high retention of chain-end functionality. Temporal control over the polymer chain growth was demonstrated by switching the ultrasound on/off due to the regeneration of activators by hydroxyl radicals formed by ultrasonication. The synthesis of a well-defined block copolymer and DNA–polymer biohybrid was also successful using this process.

Noncovalent interactions can maintain the three-dimensional structures of biomacromolecules (e.g., polysaccharides and proteins) and control specific recognition in biological systems. Supramolecular chemistry was gradually developed as a result, and this led to design and application of self-healing materials. Self-healing materials have attracted attention in many fields, such as coatings, bionic materials, elastomers, and flexible electronic devices. Nevertheless, self-healing materials for biomedical applications have not been comprehensively summarized, even though many reports have been focused on specific areas. In this Review, we first introduce the different categories of supramolecular forces used in preparing self-healing materials and then describe biological applications developed in the last 5 years, including antibiofouling, smart drug/protein delivery, wound healing, electronic skin, cartilage lubrication protection, and tissue engineering scaffolds. Finally, the limitations of current biomedical applications are indicated, key design points are offered for new biological self-healing materials, and potential directions for biological applications are highlighted.

Chemodynamic therapy (CDT) is novel and promising for cancer treatment, however, the potential systematic toxicity of the used nanoparticles is still a big concern. In this work the biocompatible hypocrellin A-Fe(III) nanoparticles (HA-Fe(III) NPs) were synthesized and studied. The CDT effect of HA-Fe(III) NPs in the dark is negligible but can be photo-activated upon red light irradiation, which is meaningful to realize precise CDT treatment by selective light irradiation. Moreover, HA-Fe(III) NPs can also generate O

The transition toward renewable energy sources requires low-cost, efficient, and durable electrocatalysts for green H

Objective. The aim of the study is to investigate the role and possible mechanism of fascin-1 (FSCN1) in the invasion, migration, glycolysis, and epithelial-mesenchymal transition (EMT) of prostate cancer. Methods. Real-time quantitative polymerase chain reaction (qRT-PCR) was utilized to determine the mRNA expression level of FSCN1 in prostate cancer tissues and prostate cancer cells PC-3 and DU145. The transwell and the scratch test were applied to detect the invasion and migration abilities of cells, respectively. A metabolic assay was used for measuring the glucose consumption, lactate production, and the extracellular acidification rate (ECAR) in cells; western blot was used for checking FSCN1, EMT, and yes-associated protein/transcriptional co-activators with the PDZ-binding motif (YAP/TAZ) signaling pathway-related protein expression level in cells or tissues. Results. FSCN1 was significantly highly expressed in prostate cancer tissues and cells. On the one hand, interference with the expression of FSCN1 could inhibit the invasion, migration, EMT, and glycolysis of prostate cancer cells. On the other hand, overexpression of FSCN1 promoted the invasion, migration, EMT, and glycolysis of prostate cancer cells. Besides, further mechanistic studies revealed that FSCN1 could activate the YAP/TAZ signaling pathway in prostate cancer cells. Conclusion. FSCN1 promotes invasion, migration, EMT, and glycolysis in prostate cancer cells by activating the YAP/TAZ signaling pathway. FSCN1 may be used as a biomarker for the diagnosis or treatment in prostate cancer.

Stimuli-responsive structurally dynamic polymers are capable of mimicking the biological systems to adapt themselves to the surrounding environmental changes and subsequently exhibiting a wide range of responses ranging from self-healing to complex shape-morphing. Dynamic self-healing polymers (SHPs), shape-memory polymers (SMPs), and liquid crystal elastomers (LCEs), which are three representative examples of stimuli-responsive structurally dynamic polymers, have been attracting broad and growing interest in recent years because of their potential applications in the fields of electronic skin, sensors, soft robots, artificial muscles, and so on. Recent advances and challenges in the developments toward dynamic SHPs, SMPs, and LCEs are reviewed, focusing on the chemistry strategies and the dynamic reaction mechanisms that enhance the performances of the materials including self-healing, reprocessing, and reprogramming. The different dynamic chemistries and their mechanisms on the enhanced functions of the materials are compared and discussed, where three summary tables are presented: A library of dynamic bonds and the resulting characteristics of the materials. Finally, a critical outline of the unresolved issues and future perspectives on the emerging developments is provided.

Conductive silicone elastomer carbon nanotubes (CNTs) composites possess potential applications in a variety of fields, including electronic skin, wearable electronics, and human motion detection. ...

To realize clinical application of antibacterial photodynamic therapy (aPDT), one of the most arduous challenges is how to render aPDT agents high selectivity against bacterial pathogens. In light of the fact that amino group-containing lipids are rich on the outer surfaces of Gram-positive bacteria, we herein constructed an alkynyl-dangling ruthenium(II) polypyridine complex (Ru2) to preferentially label Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) over mammalian cells via the amino-yne bio-orthogonal click reaction. Thanks to the strong singlet oxygen generation ability, Ru2 could photo-inactivate S. aureus and MRSA effectively and specifically. Phosphatidylethanolamine (PE) molecules also exist in mammalian cells but are not accessible for Ru2, leading to its poor binding/uptake and negligible cytotoxicity in the dark and upon irradiation towards mammalian cells as well as low hemolysis, all favorable for aPDT application.

Achieving macro-damage repair of self-healing polymer materials is highly interesting and rarely reported. Realizing the dynamic characteristics of conventional chemical bonds will generate high-density dynamic covalent bonds in polymer materials, which should be favorable for the macro-damage repairing process as their dissociation can lead to more extensive depolymerization and also more complete disruption of the network. Herein, we accidently found that classical covalent urea bonds formed by primary amine and isocyanate possessed excellent dynamic characteristics in the absence of a catalyst. Density functional theory calculation suggests that the decomposition of a small molecule urea model does not easily occur due to the high energy barrier, while the experimental FTIR study of linear polyurea confirms the occurrence of urea bond decomposition at above 110 °C due to the entropy gain of the flexible polymer chains during heating. We demonstrated a kind of dynamic crosslinked polyurea–polydimethylsiloxane elastomer, in which polydopamine nanoparticles were introduced to produce rapid photo-thermal transition properties. The obtained composite elastomers exhibit a rapid solid–liquid transition under NIR exposure due to high-density dynamic urea bonds present in the polymer network and their fast dissociation rate, and thus possess excellent macro-damage repairing and shear-free reprocessing properties.

The realization of covalent adaptable networks with excellent mechanical and dynamic properties remains a major challenge. Herein, the acylsemicarbazide (ASC) moieties with dynamic reversibility and multiple hydrogen bonding were disclosed and used to prepare transparent, high modulus, and malleable polymer networks. It was found that the ASC moiety can reversibly generate isocyanate and hydrazide at elevated temperatures, that is, exhibiting dynamic reversibility. ASC can also produce the disordered multiple hydrogen bonds that contribute to superior mechanical strength for dynamic polymers. The hydrogen bonding in ASC moieties can diminish the energy barrier for the cleavage of dynamic covalent bonds, and the dissociation of ASC moieties further promotes the disruption of hydrogen bonds, showing the synergistic dynamic effects. ASC moieties provide a valuable molecular engineering opportunity toward high-performance dynamic polymer materials. The polymer containing ASC moieties possesses excellent optical transparency, superb mechanical performance (Young's modulus up to 1.7 GPa), together with malleable and healing properties.

Liquid crystal elastomers (LCEs), a class of soft materials capable of a large and reversible change in the shape under the trigger of external stimuli, can be fabricated into diverse architectures with complicated deformation modes through four-dimensional (4D) printing. However, the printable LCE ink is only in the form of monomeric precursors and the deformation mode is limited to contraction/extension deformation. Herein, we report a novel approach to break through these limitations. We achieved 4D printing of a single-component liquid crystal polymer ink in its isotropy state through direct ink writing (DIW) technology. The drawing force imposed by the movement of nozzle in the extruded printing process was able to align the mesogen units along the specific printing path. An orientation gradient perpendicular to the printing direction was obtained due to the existence of a temperature gradient between the two sides of printed samples and could be further fixed by post-photo-cross-linking treatment through the dimerizable groups in the LCE, realizing a new actuation mode in the field of extrusion-based printing of LCE actuators. The printed film was able to change reversibly from a strip to a tightly hollow cylinder and could reversibly lift up an object with roughly 600 times its own weight. The orientation gradient can be patterned through liquid-assistant printing or programmed structure design to integrate both bending and contraction actuation modes on the same printed sample, leading to complex deformation and two-dimensional (2D) planar porous structure to three-dimensional (3D) porous cylinder transition. This study opens up a new prospect to directly print a wide variety of LCE actuators with versatile actuation modes.

Despite recent progress in graphene-based aerogels, challenges such as low mechanical strength and adsorption efficiency are still remaining. Here the reduced graphene oxide (rGO)/chitosan (CS) composite aerogel microspheres (rGCAMs) with center-diverging microchannel structures were developed by electrospraying and freeze-drying method. The optimized rGCAMs exhibit a high Young's modulus of 197 kPa and can support ~75,000 times its own weight, due to the cross-linking of CS by glutaraldehyde. Meanwhile, the rGCAMs can maintain high adsorption capacity for 15 cyclic tests due to its excellent mechanical strength. The oil adsorption kinetics and isotherms of rGCAMs follow the pseudo-second-order kinetic equation and the Langmuir model, respectively. The whole adsorption process is influenced by the oil diffusion in the liquid matrix and also in the intra-particle of aerogel microspheres. Moreover, rGCAMs can also be used to separate both surfactant-stabilized water-in-oil and oil-in-water emulsions through demulsification. The high-strength, recyclable and separation-efficient rGCAMs can be a potential candidate for oily wastewater treatment.

Self-healing coatings that are able to self-repair after being damaged represent an effective solution to provide a reliable and long-lasting protection of the underlying substrate. In this work, we developed self-healing waterborne polyurethane (PU) coatings through the introduction of Diels-Alder bonds in the polymer backbone. Although heat is typically used as trigger, here we exploited photothermal converters to allow also NIR light-induced self-healing. To this aim, we synthesized (3-aminopropyl)-triethoxysilane-modified graphene oxide nanosheets that were subsequently coated by nanometric polydopamine particles, which serve for imparting to the coating the NIR-responsive self-healing feature. Fourier transform infrared and X-ray photoelectron spectroscopy confirmed the successful synthesis of PDA-coated reduced graphene oxide nanoparticles, which were thus exploited to prepare nanocomposite PU coatings on bronze substrates on which they exhibited good adhesion. Once scratched, fast and effective self-healing was ensured upon irradiation with NIR light for only 30 s. In addition, electrochemical impedance spectroscopy analyses proved that the nanocomposite coatings exhibited improved barrier properties which resulted in an enhanced protection of the underlying metal from corrosion.

Organic coatings are extensively investigated as possible solution to prevent or at least retard the occurring of corrosion processes on metal surfaces. Their actual breakthrough is still hampered by the risk of barrier properties loss because of local failure of the coating integrity. To address this issue, self-healing coatings, which are intrinsically able to recover from damages upon exposure to external stimuli, are currently gaining increasing attention. Herein, waterborne polyurethanes (PU) are synthesized, and a Diels-Alder adduct is added into the polymeric backbone to endow the material with self-healing functionality. The effect of different diisocyanate in PU synthesis is explored, namely isophorone diisocyanate, 4,4 '-dicyclohexylmethane diisocyanate (HMDI), and hexamethylene diisocyanate. The obtained results highlight the key role of the interactions among soft and hard segments in ultimately defining the coating performances. Actually, the combination of Fourier transform infrared spectroscopy, atomic force microscopy and X-ray diffration analysis reveals that the HMDI-based PU have showed the best balance in terms of H-bonding strength among hard segments and crystallinity degree in the soft ones. This allows to reach a good compromise in terms of mechanical resistance, anticorrosion properties, and self-healing ability.

Background Alterations in RNA-binding proteins (RBPs) are reported in various cancer types; however, the role of RBPs in bladder urothelial cancer (BLCA) remains unknown. This study aimed to systematically examine the function and prognostic significance of RBPs in bladder cancer using bioinformatics analyses. Methods RNA sequencing and clinical data for BLCA were downloaded from The Cancer Genome Atlas (TCGA) database, and differentially expressed RBPs (DERBPs) between normal and cancer tissues were identified. Protein-protein interaction (PPI) network of DERBPs was established, and enrichment analysis and visualizations were performed. A total of 404 patients with BLCA from TCGA database were randomly divided into training and testing groups. A prognostic model was constructed using the data from training group, and validated in the testing group. Receiver operating characteristic (ROC) curve and survival analysis were performed to explore the prognostic value of the model. A nomogram was established to predict survival in bladder cancer patients. Finally, the verification of prognosis-related hub RBP survival analysis were performed. Results A total of 388 DERBPs were identified, including 219 upregulated and 169 downregulated RBPs. All RBPs were screened for prognostic model establishment and 9 RBPs (TRIM71, YTHDC1, DARS2, XPOT, ZNF106, FTO, IPO7, EFTUD2, and CTU1) were regarded as prognosis-related hub RBPs in BLCA. Further analysis revealed worse overall survival (OS) in the high-risk cohort compared to the model-based low-risk cohort. The area under the ROC curve was 0.752 in the training group and 0.701 in the testing group, which confirms the good prediction ability. A nomogram was established according to nine prognosis-related RBPs, which showed well predicting ability for BLCA. BLCA patients with high DARS2, XPOT, ZNF106, FTO, and IPO7 expression (on the contrary, low YTHDC1 and CTU1 expression) were correlated to poor overall survival. Conclusions The prognosis-related hub RBPs may be involved in oncogenesis, development, and metastasis of BLCA. Our results will be of great significance in revealing the pathogenesis of BLCA, and developing new therapeutic targets and prognostic molecular markers.

Atom transfer radical polymerization (ATRP) has been previously mediated by ultrasound using a low concentration of copper complex in water (sono-ATRP) or by addition of piezoelectric materials in organic solvents (mechano-ATRP). However, these procedures proceeded slowly and yielded polymers contaminated by new chains initiated by hydroxyl radicals or by residual piezoelectrics. Unexpectedly, in the presence of sodium carbonate, rapid sono-ATRP of methyl acrylate in DMSO was achieved (80% conversion in

Self-healing polymer materials have drawn rapidly increasing interest over the last decade, and have been studied and used in an ever-increasing range of applications. Herein, we successfully make the covalent urea bond – a pinnacle of stability due to strong resonance effects – dynamic in nature through mediation of zinc salts. The dynamic covalent character of urea in the presence of zinc ions is confirmed through dissociation reaction experiments and quantum chemical calculations of small-molecule model urea compounds. In line with our experiments, the modelling results suggest that the presence of zinc ions speeds up the reaction of urea dissociation by two orders of magnitude via the formation of O-bound Zn complexes. Based on such dynamic covalent urea bonds, we then develop a novel class of self-healing polymer materials with excellent healing efficiencies. Different kinds of self-healing and reprocessable polyurea materials were prepared, with polymer properties that can be easily tuned by varying the degree of crosslinking and the molecular weight of the siloxane precursor. Since different kinds of self-healing polyurea materials could easily be prepared due to the commercial availability of a very wide range of amine and isocyanate monomers, this introduction of self-healing properties is expected to have significant potential in a range of applications, such as coatings, paints, and 3D printing. In addition, this introduces polyureas and other urea-containing polymers as a class of highly stable, yet easily reprocessable plastics, which is highly relevant given the globally desired more sustainable use of plastics.

Significant advances have been made in the development of self-healing synthetic polymer materials in recent years. This review article discusses the recent progress in preparation, characterization and properties of different kinds of intrinsic self-healing elastomers based on reversible covalent bonds and dynamic supramolecular chemistry. Healing conditions, mechanical property recovery and healing efficiency are the main discussion topics. Potential applications, challenges and future prospects in self-healing elastomer fields are also discussed in the last part of this review.

Sonar is an important means of underwater target detection. However, the existing sonar measurement method does not use a third-party object as a reference, which makes it difficult to measure underwater targets. In this paper, we propose an angle measurement method and a 3D mapping algorithm based on sonar images and artificial landmarks. By combining acoustic and visual methods, using the known size information of artificial landmarks as a reference, we can calculate the target information to realize the mapping between real space and sonar images. Before verifying the feasibility, we processed the sonar image, denoised it with a median filter, enhanced the landmark image with the Sauvola algorithm, and finally introduced two data fitting methods to extract the edge information of artificial landmarks, so as to help us find the key points more accurately. The experimental results show that the accuracy of our method can reach the millimeter level, and the error range is within 5%. The technology proposed in this paper realizes the shape correction and precise length measurement of underwater targets.

High-intensity Focused Ultrasound (HIFU) was used to stimulate the embedded copper sulfate (CuSO4) particles to release from the crosslinked poly (methyl methacrylate-co-butyl acrylate) copolymer solid matrix. In order to better understand the ultrasound release mechanism for drug/polymer delivery systems, the synchrotron radiation X-ray computed microtomography (SR-CT) was used to non-destructively investigate the structure of drug/polymer delivery systems after different HIFU treatment time. For the first time, we clearly demonstrate that ultrasonic waves can overcome the constraints of the polymer chain and drive the filler to move from the strong region to the weak region in the solid polymer matrix, thus resulting in a change in distribution of the filler in solid polymers. This result also demonstrates that SR-CT is a powerful technique which can be used to quantitatively study the 3D structure of fillers/polymers composite as it can take a broader and overall view than the conventional localized two-dimensional analysis method such as SEM, TEM.

A pH- and ultrasound dual-responsive drug release pattern was successfully achieved using mesoporous silica nanoparticles (MSNs) coated with polydopamine (PDA). In this paper, the PDA shell on the MSN surface was obtained through oxidative self-polymerization under the alkaline condition. The morphology and structure of this composite nanoparticle were fully characterized by a series of analyses, such as infrared (IR), transmission electron microscopy, and thermogravimetric analysis. Doxorubicin hydrochloride (DOX)-loaded composite nanoparticles were used to study the performances of responsive drug storage/release behavior, and this kind of hybrid material displayed an apparent pH response in DOX releasing under the acidic condition. Beyond that, upon high-intensity focused ultrasound exposure, loaded DOX in composite nanoparticles was successfully triggered to release from pores because of the ultrasonic cavitation effect, and the DOX-releasing pattern could be optimized into a unique pulsatile fashion by switching the on/off status. From the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, it was observed that our blank nanoparticles showed no toxicity to HeLa cells, but DOX-loaded nanoparticles could inhibit the growth of tumor cells. Furthermore, these composite nanoparticles displayed an effective near-IR photothermal conversion capability with a relatively high conversion efficiency (∼37%). These as-desired drug delivery carriers might have a great potential for future cancer treatment that combine the chemotherapy and photothermal therapy.