The fabrication of highly durable skin‐mimicking sensors remains challenging because of the unavoidable fatigue and physical damage that sensors are subjected to in practical applications. In this study, ultra‐durable ionic skins (I‐skins) with excellent healability and high sensitivity are fabricated by impregnating ionic liquids (ILs) into a mechanically robust poly(urea‐urethane) (PU) network. The PU network is composed of crystallized poly(ε‐caprolactone) and flexible poly(ethylene glycol) that are dynamically cross‐linked with hindered urea bonds and hydrogen bonds. Such a design endows the resultant ionogels with high mechanical strength, good elasticity, Young's modulus similar to that of natural skin, and excellent healability. The ionogel‐based I‐skins exhibit a high sensitivity to a wide range of strains (0.1–300%) and pressures (0.1–20 kPa). Importantly, the I‐skins show a highly reproducible electrical response over 10 000 uninterrupted strain cycles. The sensing performance of the I‐skins stored in open air for 200 days is almost the same as that of the freshly prepared I‐skin. The fractured I‐skins can be easily healed by heating at 65 °C that restores their original ultra‐durable sensing performance. The long‐term durability of the I‐skins is attributed to the combination of non‐volatility of the ILs, excellent healability, and well‐designed mechanical properties.
Hydrogel-based self-healing ionic skins possess high mechanical strength, excellent resilience, anti-freezing properties and high sensitivity and can heal fatigue and mechanical damage to restore the original sensing performance.
It is challenging to develop healable elastomers with combined high mechanical strength and good elasticity. Herein, a simple strategy to develop high-performance elastomers that integrate high mechanical strength, enormous stretchability, good resilience, and healability is reported. Through simply complexing poly(acrylic acid) and poly(ethylene oxide) based on hydrogen-bonding interactions, transparent composite materials that perform as elastomers are generated. The as-prepared elastomers exhibit mechanical strength (true strength at break) and toughness (fracture energy) as high as 61 MPa and 22.9 kJ/m, respectively, and they can be stretched to >35 times their initial length and are able to return to their original dimensions following the removal of stress. Further, the elastomers are capable of healing from physical cuts/damages in a humid environment because of reformation of the reversible hydrogen bonds between the polymer components. The high mechanical strength of the elastomers is ascribed to the high degree of polymer chain entanglements and multiple hydrogen-bonding interactions in the composites. The reversible hydrogen bonds, which act as cross-linkages, facilitate the unfolding and sliding of the polymer chains in the composites, thereby endowing the elastomers with good elasticity and healability. Furthermore, flexible conductors with water-enabled healability were developed by drop-casting Ag nanowires on top of the elastomers.
During the exploration of highly efficient noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER), a promising and challenging strategy is to fabricate composite nanocatalysts by finely tuning metal and/or nonmetal element components. Herein, we report a new HER electrocatalyst, which is composed of molybdenum phosphide and molybdenum carbide composite nanoparticles (NPs) coated by few-layer N-doped graphitic carbon shells (denoted as MoP/MoC@C). Such a new combination mode of electrocatalysts is realized by a one-step annealing route with the mixture of a Mo/P-based polyoxometalate (POM) and dicyandiamide. On the basis of this method, the simultaneous phosphorization and carbonization in a nanoscale confined space can be easily achieved by the use of POM as the molecular-element-regulating platform. MoP/MoC@C exhibits more remarkable HER performance over the whole pH range than those of MoP, MoC, and the physical mixture of MoP and MoC. The low overpotentials of 89, 136, and 75 mV were obtained at a current density of 10 mA cm in the media of pH = 0, 7, and 14, respectively. Furthermore, MoP/MoC@C shows a long-term durability for 14 h over the entire pH range (0-14). Because of the protection of carbon shells, such composite electrocatalyst also possesses better transition-metal tolerance exemplified by Fe, Co, and Ni than that of 20% commercial Pt/C. This work demonstrates the advantage of POM precursors in adjusting the component and properties of nanoscale composite electrocatalysts for HER, which may suggest new options for the fabrication of highly efficient composite electrocatalysts.
degradation generally requires harsh and strictly controlled conditions. [5,8,9] Moreover, the number of plastic types that are capable of being fully and efficiently degraded by such methods is very less. Therefore, the most effective approach to solve the issue of plastic waste accumulation consists in substituting traditional plastics with novel plastics that can be fully degraded into environmentally friendly substances in natural environments. [10-18] Poly(lactic acid) (PLA) can be degraded into CO 2 and H 2 O by microorganisms under specific and controlled humidity and temperature conditions. [16,19,20] Currently, degradable PLA is widely used in biomedical equipment, food packaging, and disposable tableware. [16] Nevertheless, to meet a wide range of applications, the development of new types of degradable plastics remains crucial. [10,14,21] In particular, it is necessary to develop plastics that are capable of complete degradation under natural environmental conditions. Poly(vinyl alcohol) (PVA) production is cost-effective, and the material itself possesses desirable degradability, nontoxicity, high tensile strength, and excellent flexibility. [11,22-26] In natural environments, PVA can be fully degraded into CO 2 and H 2 O by microorganisms through the oxidation of PVA hydroxyl groups into diketones and the subsequent hydrolysis of carbon-carbon diketone bonds. [11,22,27,28] Therefore, PVA-based plastics are environmentally friendly and degradable, and they can be used for a wide range of potential applications. [29,30] PVA-based plastics have been fabricated by complexation of PVA with partner species such as inorganic nanofillers, [31] organic molecules, [32] and polymers [25,30] containing complementary noncovalent interactions. However, because of the water solubility of PVA, these PVA-based plastics absorb water from the environment and exhibit lower mechanical strength compared to those of PEbased plastics in watery environments. This limitation restricts the applications of PVA-based plastics and increases their storage cost. Commercially available poly(vinyl formal) (PVF) and poly(vinyl butyral) (PVB), which are synthesized via an acid-catalyzed acetal reaction between the PVA hydroxyl groups and the aldehyde groups of formaldehyde and n-butyraldehyde, respectively, exhibit good water resistance. However, PVF and PVB are difficult to be degraded in soil because of their high acetalization ratios (usually higher than ≈70%). [33,34] Therefore, it is necessary to fabricate PVA-based degradable plastics that can maintain sufficiently high mechanical strength in watery
Cancer patients are at high risk for suicide, particularly when they are informed about the cancer diagnosis or hospitalized for cancer treatment. Therefore, oncology healthcare settings such as large general hospitals in China, may represent an ideal setting to identify and treat suicidality in cancer patients. However, the clinical epidemiology of suicidality of Chinese cancer patients remains largely unknown. This study examined the prevalence and correlates of suicidal ideation among Chinese cancer inpatients of large general hospitals. A total of 517 cancer inpatients were consecutively recruited from two tertiary general hospitals of a metropolitan city in northern China, and administered with standardized questionnaires to collect data on sociodemographics, mental health, and cancer-related clinical characteristics. Suicidal ideation and mental health were measured with a single self-report question “In the past month, did you think about ending your life?” and Hospital Anxiety and Depression Scale, respectively. The one-month prevalence of suicidal ideation was 15.3% in Chinese cancer inpatients. In multivariable Logistic regression, depression, anxiety, moderate-to-severe pain, metastatic cancer, poor performance status, surgery, and palliative care were significantly associated with suicidal ideation. Cancer inpatients of large Chinese general hospitals have high prevalence of suicidal ideation and therefore potentially at high risk for suicide. Suicide prevention efforts for cancer inpatients should include periodic evaluation of suicidality, effective pain management, psychooncological supports, and, when necessary, psychiatric treatment and crisis intervention.
Polymeric antifogging/frost-resisting coatings are suitable for use on flexible substrates but are vulnerable to accidental scratches and cuts. To solve this problem, we present the fabrication of healable, highly transparent antifogging and frost-resisting polymeric coatings via the layer-by-layer assembly of poly(ethylenimine) (PEI) and a blend of hyaluronic acid and poly(acrylic acid) (HA-PAA). Due to their remarkable water-absorbing capability, the highly transparent and flexible (PEI/HA-PAA)*50 coatings show excellent antifogging and frost-resisting capabilities even under aggressive fogging and frosting conditions. Meanwhile, these coatings can conveniently and repeatedly heal scratches and cuts several tens of micrometers deep and wide in the same region upon exposure to water because of the dynamic nature of the PEI/HA-PAA coatings. The healability of the (PEI/HA-PAA)*50 coatings provides a new way to design transparent antifogging/frost-resisting polymeric coatings with high flexibility, enhanced reliability, and extended service life.
Transparent and healable ionogels with very high mechanical strength, ionic conductivity, and resilience were fabricated for use as strain sensors with satisfactory reliability. The ionogels were fabricated by casting an aqueous solution of poly(vinyl alcohol) (PVA)–poly(vinylpyrrolidone) (PVP) complexes and 1-ethyl-3-methylimidazolium dicyanamide ([EMIm][DCA]), followed by evaporation of water at room temperature. The use of [EMIm][DCA] endowed the resulting ionogels with ionic conductivity at room temperature as high as 19.7 mS cm–1. Owing to the synergy between the abundant number of hydrogen bonds between PVA and PVP and the crystallized PVA segments that served as nanofillers, the resulting ionogels had good mechanical properties with a tensile stress of 7.7 MPa, a strain of 821%, and good resilience. In addition, the resulting ionogels showed rapid and repeatable sensing signals over a wide strain range (0.1–400%). This enabled them to detect both vigorous muscle movements, such as walking and jumping, and subtle muscle movements, such as pulse. Moreover, owing to the reversibility of hydrogen bonds, physically damaged mechanical properties, conductivity, and sensing ability of the ionogels could be conveniently healed with the assistance of water.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.