Halloysite is an alumosilicate tubular clay with a diameter of 50 nm, an inner lumen of 15 nm and a length of 600–900 nm. It is a natural biocompatible nanomaterial available in thousands of tons at ...low price, which makes it a good candidate for nanoarchitectural composites. The inner lumen of halloysite may be adjusted by etching to 20–30% of the tube volume and loading with functional agents (antioxidants, anticorrosion agents, flame‐retardant agents, drugs, or proteins) allowing for formulations with sustained release tuned by the tube end‐stoppers for hours and days. Clogging the tube ends in polymeric composites allows further extension of the release time. Thus, antioxidant‐loaded halloysite doped into rubber enhances anti‐aging properties for at least 12 months. The addition of 3–5 wt% of halloysite increases the strength of polymeric materials, and the possibility of the tube's orientation promises a gradient of properties. Halloysite nanotubes are a promising mesoporous media for catalytic nanoparticles that may be seeded on the tube surface or synthesized exclusively in the lumens, providing enhanced catalytic properties, especially at high temperatures. In vitro and in vivo studies on biological cells and worms indicate the safety of halloysite, and tests for efficient adsorption of mycotoxins in animals' stomachs are also carried out.
Halloysite, 50 nm diameter tubular clay, is a natural biocompatible material available in thousands of tons. Its inner lumen may be etched, doubling the lumen's volume, and loaded with functional agents, such as antioxidants, anticorrosion materials, flame‐retardants, catalysts, drugs, or proteins, enabling sustained controlled release tuned for hours, days, or months.
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Reinforcement, recycling, and functional applications are three important issues in elastomer science and engineering. It is of great importance, but rarely achievable, to integrate these properties ...into elastomers. Herein, we report a simple way to prepare covalently cross-linked yet recyclable, robust, and macroscopically responsive elastomer vitrimers by engineering exchangeable bonds into rubber–carbon nanodot (CD) interphase using CD as high-functionality cross-linker. The cross-linked rubbers can rearrange the network topology through transesterification reactions in the interphase, conferring the materials the ability to be recycled, reshaped, and welded. The relatively short chains bridging adjacent CD are highly stretched and preferentially rupture to dissipate energy under external force, resulting in remarkable improvements on the mechanical properties. Moreover, the malleable and welding properties allow the samples to access reconfigurable/multiple shape memory effects.
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Healable, adhesive, wearable, and soft human‐motion sensors for ultrasensitive human–machine interaction and healthcare monitoring are successfully assembled from conductive and human‐friendly hybrid ...hydrogels with reliable self‐healing capability and robust self‐adhesiveness. The conductive, healable, and self‐adhesive hybrid network hydrogels are prepared from the delicate conformal coating of conductive functionalized single‐wall carbon nanotube (FSWCNT) networks by dynamic supramolecular cross‐linking among FSWCNT, biocompatible polyvinyl alcohol, and polydopamine. They exhibit fast self‐healing ability (within 2 s), high self‐healing efficiency (99%), and robust adhesiveness, and can be assembled as healable, adhesive, and soft human‐motion sensors with tunable conducting channels of pores for ions and framework for electrons for real time and accurate detection of both large‐scale and tiny human activities (including bending and relaxing of fingers, walking, chewing, and pulse). Furthermore, the soft human‐motion sensors can be enabled to wirelessly monitor the human activities by coupling to a wireless transmitter. Additionally, the in vitro cytotoxicity results suggest that the hydrogels show no cytotoxicity and can facilitate cell attachment and proliferation. Thus, the healable, adhesive, wearable, and soft human‐motion sensors have promising potential in various wearable, wireless, and soft electronics for human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.
Flexible, wearable, healable, and adhesive soft strain sensors are successfully developed from a conductive and biocompatible hybrid hydrogel framework for ultrasensitive human–machine interaction and healthcare monitoring. They exhibit fast self‐healing ability (within 2 s), highly self‐healing efficiency (99%), robust self‐adhesiveness, and a tunable conducting framework for real‐time, wireless, and accurate detection in human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.
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Owing to the development of nanotechnology and noninvasive treatment, thermal therapy in combination with external stimuli has been applied for tissue engineering and regenerative medicine (TERM), ...which has attracted more and more attention in recent years. In this review, the recent progress of applying a variety of non‐invasive thermal therapeutic modalities for TERM, including photothermal therapy, magnetic thermotherapy, and ultrasound thermotherapy, as well as other thermal therapeutics are discussed. The parameters and conditions that need to be considered and regulated to realize a well‐controlled thermal therapy for tissue regeneration are also discussed. Afterwards, the current concerns and challenges of putting thermal therapy into clinical applications are pointed out. At last, perspectives are provided for the future development directions, aiming to providing opportunities and a novel pathway for TERM.
Owing to the development of nanotechnology and non‐invasive treatment, thermal therapy in combination with external stimuli has been applied for tissue engineering and regenerative medicine, which has attracted more and more attention in recent years. Among them, photothermal therapy, magnetic thermotherapy, and ultrasound thermotherapy show attractive charm due to their convenient regulation and precise thermal positioning.
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•This article reviews the surface modification methods of aramid fiber and its composite materials.•Interfacial adhesion is important for aramid fiber reinforced composites.•The ...interfacial stress transfer mechanism of aramid fiber reinforced composites is still unclear.
Aramid fiber (AF), which has excellent comprehensive properties such as low density, high specific strength, and high specific modulus, is widely used in composites reinforcement. AF-reinforced composites (AFRPs), which are very suitable for preparing advanced engineering materials, have drawn much attention due to their excellent properties. However, the smooth and chemically inert surface of the AF severely limits its applications. Various methods have been conducted to modify the surface of AF to improve the interfacial adhesion between fiber and matrix. The purpose of surface modification of AF is to improve the surface chemical activity and increase the surface roughness, which aims to achieve an excellent chemical bonding and mechanical interlocking between fiber and matrix. The major focus of this review is the surface and interface modification of AF. In this review, we briefly summarize the recent progress of different surface modification methods of AF and its reinforcement to polymers. Finally, some existing problems of AFRPs as well as future research prospects are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Computer simulations are an important implementation to experimental methods working on polymer nanocomposites (PNCs), which have advanced properties because of their unique hierarchy ...microstructures. In this paper, different computer simulation methods applied to investigate the structures and properties of PNCs and the simulation predicted physical properties of PNCs are reviewed. The fundamentals of applying molecular dynamics simulation method to calculate different physical properties of PNCs are explained accompanied with detailed examples. The results can help to understand the progress on PNC field using simulation methods especially different-sized molecular dynamics simulation methods.
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•Diverse kinds of computer simulation methods were reviewed and compared.•Simulation results of multiple physical properties were explored.•The fundamentals of calculating different physical properties using simulation methods were explained.
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Mimicking natural structures has been highly pursued in the fabrication of synthetic polymeric materials due to its potential in breaking the bottlenecks in mechanical properties and extending the ...applications of polymeric materials. Recently, it has been revealed that the energy dissipating mechanisms
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sacrificial bonds are among the important factors which account for strong and tough attributes of natural materials. Great progress in synthesis of polymeric materials consisting of sacrificial bonds has been achieved. The present review aims at (1) summarizing progress in the mechanics and chemistry of sacrificial bond bearing polymers, (2) describing the mechanisms of sacrificial bonds in strengthening/toughening polymers based on studies by single-molecule force spectroscopy, chromophore incorporation and constitutive laws, (3) presenting synthesis methods for sacrificial bonding including dual-crosslink, dual/multiple-network, and sacrificial interfaces, (4) discussing the important advances in engineering sacrificial bonding into hydrogels, biomimetic structures and elastomers, and (5) suggesting future works on molecular simulation, viscoelasticity, construction of sacrificial interfaces and sacrificial bonds with high dissociative temperature. It is hoped that this review will provide guidance for further development of sacrificial bonding strategies in polymeric materials.
This review focuses on the mechanisms, designs, and applications of bio-inspired sacrificial bonds in artificial polymeric materials.
A novel biomimetic surface modification method for meta-aramid (MPIA) fibers and the improvement on adhesion with rubber matrix was demonstrated. Inspired by the composition of adhesive proteins in ...mussels, we used dopamine (DOPA) self-polymerization to form thin, surface-adherent poly(dopamine) (PDA) films onto the surface of MPIA fibers simply by immersing MPIA fibers in a dopamine solution at room temperature. An epoxy functionalized silane (KH560) grafting was then carried out on the surface of the poly(dopamine)-coated MPIA, either by a “one-step” or “two-step” method, to introduce an epoxy group onto the MPIA fiber surface. The surface composition and microstructure of the modified MPIA was characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated successful grafting of KH560 on the PDA-coated MPIA surface. A single-fiber pull-out test was applied to evaluate the adhesion of MPIA fibers with the rubber matrix. Compared with the untreated MPIA fibers, the adhesion strength between the modified MPIA fibers by “one step” method with rubber matrix has an increase of 62.5%.
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It is a great challenge to fully understand the microscopic dispersion and aggregation of nanoparticles (NPs) in polymer nanocomposites (PNCs) through experimental techniques. Here, coarse-grained ...molecular dynamics is adopted to study the dispersion and aggregation mechanisms of spherical NPs in polymer melts. By tuning the polymer–filler interaction in a wide range at both low and high filler loadings, we qualitatively sketch the phase behavior of the PNCs and structural spatial organization of the fillers mediated by the polymers, which emphasize that a homogeneous filler dispersion exists just at the intermediate interfacial interaction, in contrast with traditional viewpoints. The conclusion is in good agreement with the theoretically predicted results from Schweizer et al. Besides, to mimick the experimental coarsening process of NPs in polymer matrixes (ACS Nano 2008, 2, 1305), by grafting polymer chains on the filler surface, we obtain a good filler dispersion with a large interparticle distance. Considering the PNC system without the presence of chemical bonding between the NPs and the grafted polymer chains, the resulting good dispersion state is further used to investigate the effects of the temperature, polymer–filler interaction, and filler size on the filler aggregation process. It is found that the coarsening or aggregation process of the NPs is sensitive to the temperature, and the aggregation extent reaches the minimum in the case of moderate polymer–filler interaction, because in this case a good dispersion is obtained. That is to say, once the filler achieves a good dispersion in a polymer matrix, the properties of the PNCs will be improved significantly, because the coarsening process of the NPs will be delayed and the aging of the PNCs will be slowed.
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Highly sensitive, wearable and durable strain sensors are vital to the development of health monitoring systems, smart robots and human machine interfaces. The recent sensor fabrication progress is ...respectable, but it is limited by complexity, low sensitivity and unideal service life. Herein a facile, cost‐effective and scalable method is presented for the development of high‐performance strain sensors and stretchable conductors based on a composite film consisting of graphene platelets (GnPs) and silicon rubber. Through calculation by the tunneling theory using experimental data, the composite film has demonstrated ideal linear and reproducible sensitivity to tensile strains, which is contributed by the superior piezoresistivity of GnPs having tunable gauge factors 27.7–164.5. The composite sensors fabricated in different days demonstrate pretty similar performance, enabling applications as a health‐monitoring device to detect various human motions from finger bending to pulse. They can be used as electronic skin, a vibration sensor and a human‐machine interface controller. Stretchable conductors are made by coating and encapsulating GnPs with polydimethyl siloxane to create another composite; this structure allows the conductor to be readily bent and stretched with sufficient mechanical robustness and cyclability.
Sensors and conductors are fabricated from developed graphene/elastomer composites. Demonstrating response time below 50 ms, high cycling durability and a gauge factor of over 100, the sensors work well as a health‐monitoring device, sound signal collector and human‐machine interface detector. The conductors can be readily bent and stretched with exceptional mechanical robustness and cyclability.
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