Characterization and properties of UV-curable hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO2 hybrid coatings.

A series of new UV-curable hybrid coatings were prepared with hyperbranched polyurethane acrylate-polyurethane diacrylate (HBPUA-PUDA) and organic SiO2 as formation, and 2-hydroxyl-2-methyl-l-phenyl-1-propanone (Darocur 1173) was used as photo-initiator. The effect of organic SiO2 content on the thermal stability and conversion of C=C bonds of the UV-cured HBPUA-PUDA/SiO2 films were evaluated using thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The morphology of SiO2 were observed by using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and the elemental composition of SiO2 was tested by energy dispersive spectrometer (EDS). The results revealed that when organic SiO2 content was less than 30 wt%, the average particle size of SiO2 was about 95 nm and the particles were well-dispersed in the organic phase. The mechanical properties, abrasion resistance and transmittance of the films were also investigated. The results showed that with the increase of organic SiO2 content, the adhesive force and pendulum hardness were increased obviously, while the transmittance and flexibility were decreased. When the content of the organic SiO2 was 30 wt%, the film of HBPUA-PUDA/SiO2 showed the optimal comprehensive performance as follows: pendulum hardness was 0.74, transmittance was 93.1%, adhesion was 0 grade, flexibility was 2 mm, impact strength was 43 Kg x cm and mass loss of 300 cycles was 12.9 mg.

Multifunctional cellulose-based aerogel for intelligent fire fighting.

Multifunctional biomass-based aerogels with mechanically robust and high fire safety are urgently needed for the development of environmentally-friendly intelligent fire fighting but challenging. Herein, a novel polymethylsilsesquioxane (PMSQ)/cellulose/MXene composite aerogel (PCM) with superior comprehensive performance was fabricated by ice-induced assembly and in-situ mineralization. It exhibited light weight (16.2 mg·cm-3), excellent mechanical resilience, and rapidly recovered after being subjected to the pressure of 9000 times of its own weight. Moreover, PCM demonstrated outstanding thermal insulation, hydrophobicity and sensitive piezoresistive sensing. In addition, benefiting from the synergism of PMSQ and MXene, PCM displayed good flame retardancy and improved thermostability. The limiting oxygen index of PCM was higher than 45.0 %, and it quickly self-extinguished after being removed away from fire. More importantly, the rapid electrical resistance reduction of MXene at high temperature endowed PCM with sensitive fire-warning capability (trigger time was less than 1.8 s), which provided valuable time for people to evacuate and relief. This work provides new insights for the preparation and application of the next-generation high performance biomass-based aerogels.

Wearable RGO/MXene Piezoresistive Pressure Sensors with Hierarchical Microspines for Detecting Human Motion.

Flexible piezoresistive pressure sensors may exhibit excellent sensing performances to be applied in wearable electronics, medical diagnosis, and electronic skin. Herein, we report a multi-layer and phased-responsive reduced graphene oxide/MXene-based piezoresistive pressure sensor with hierarchical microspines constructed by sandpaper as the template. Thanks to the multi-level and multi-layer structure, the obtained sensor realized phased response and showed wide detection range (up to 70 kPa), fast response (response/recovery time of 40/80 ms), and excellent working stability (1000 fatigue cycles). Furthermore, the sensor was successfully applied for detecting various human motions including pulse beats, cheek bulging, nodding, finger bending, speech recognition, handwriting, and other pressure signals. Besides, a 6 × 6 sensing matrix integrated by the sensors was able to sensitively perceive the distribution of plane pressure. The findings in this work conceivably stand out as a new strategy to fabricate high-performance piezoresistive pressure sensors in the fields of intelligent healthcare and medical diagnosis, wearable electronic devices, electronic skin, and human-machine interaction.

Skin-inspired flexible and high-performance MXene@polydimethylsiloxane piezoresistive pressure sensor for human motion detection.

In recent years, flexible high-performance piezoresistive pressure sensors have attracted considerable attention for the important application potential in the emerging fields of smart robots, wearable electronics and electronic skin. Herein, inspired by human skin, a new strategy was proposed for the fabrication of a double-layer piezoresistive pressure sensor with wide sensing range and high sensitivity. It was based on the utilization of sandpaper as template and MXene for the constructions of micro-protrusion rough surface on polydimethylsiloxane film and electrically conductive pathways, respectively. The prepared sensor demonstrated high sensitivity of 2.6 kPa-1 in wide linear range of 0-30 kPa, fast response/recovery time of 40/40 ms and excellent repeatability. Importantly, the sensor was successfully applied for the real-time detection of radial artery heart rate, limb movement, handwriting and vocal cord vocalization. Moreover, the integrated device by the sensors had the capability of identifying and visualizing spatial pressure distribution. The findings conceivably stand out a new methodology to prepare flexible high-performance piezoresistive pressure sensors for wearable electronics, human-computer interaction, intelligent robots and health monitoring.

Degradable and stretchable bio-based strain sensor for human motion detection.

In recent years, flexible strain sensors have attracted considerable attention for the great application potential in the emerging fields of wearable devices, electronic skin and health monitoring. However, most of flexible strain sensors are nondegradable, and the produced numerous electronic wastes after uselessness will seriously threaten environment and ecology. Herein, we propose a new strategy to fabricate degradable and stretchable bio-based strain sensor using candle soot (CS) particles to construct conductive pathways and chitosan, potato starch (PS), and polyvinyl alcohol (PVA) to form stretchable matrix in the presence of Fe3+ ions. Owing to the formation of multiple hydrogen bonding constructed by chitosan, PS and PVA as well as coordination bonding by Fe3+ ions, the obtained strain sensor showed high elongation at break up to 200% and good fatigue resistance. Furthermore, the firm embedding of the CS particles into the surface of the stretchable matrix endowed the strain sensor with steady sensitivity (gauge factors of 1.49 at 0-60% strain and 2.71 at 60-100% strain), fast response (0.22 s) and good repeatability even after 1000 stretching-releasing cycles. In addition, the strain sensor was successfully applied to detect various human motions including finger and wrist bending, swallowing and pronunciation. Interestingly, after connecting to an Arduino microcontroller circuit with a Bluetooth module, the strain sensor was able to wirelessly detect real-time movements of index finger joints. Different from most previously reported sensors, the prepared strain sensor in this work was completely degraded in 2 wt% CH3COOH solution at 90 °C only within 10 min, thus effectively avoiding the production of electrical waste after the updating and upgrading of the sensors. The findings conceivably stand out as a new methodology to prepare environmental-friendly sensors in the field of flexible electronics, which is very beneficial for the sustainable development of environment and society.

Functional Epoxy Elastomer Integrating Self-Healing Capability and Degradability for a Flexible Stretchable Strain Sensor.

With the rapid development of flexible electronics and the increasing deterioration of the natural environment, functional and environmentally friendly flexible strain sensors have become one of the frontier research hotspots. Here, we propose a novel strategy to synthesize a functional epoxy elastomer integrating self-healing capability and degradability for flexible stretchable strain sensors. A carboxyl-terminated epoxy prepolymer was first synthesized using carboxyl-terminated PEG (PEG-COOH), 2,2'-dithiodibenzoic acid (DTSA), and 1,4-butanediol diglycidyl ether (BDDE), and then crosslinked by epoxidized soybean oil (ESO) to yield an epoxy elastomer. The obtained elastomer exhibited not only high tensile stress (5.07 MPa), large stretchability (477%), and high healing efficiency (92.5%) but also superior degradability in alkaline aqueous solution. The elastomer-based stretchable strain sensor with microstructure showed high sensitivity (GF = 176.71) and was successfully applied for detecting human motions and recognizing objects with various shapes. Moreover, the healed sensor could restore stable sensing ability. The prepared functional epoxy elastomer is of great significance for the preparation of environmentally friendly and high-performance sensors and is promising for applications in the fields of healthcare monitoring, intelligent robots, and wearable electronics.

Light Stimuli-Responsive Superhydrophobic Films for Electric Switches and Water-Droplet Manipulation.

Fabrication of superhydrophobic films with large and sensitive deformed actuations driven by light stimuli for the emerging application fields such as biomimetic devices, artificial muscles, soft robotics, electric switches, and water-droplet manipulation remains challenging. Herein, a facile strategy is proposed to fabricate a light stimuli-responsive superhydrophobic film (LSSF) by integrating a bottom carbon nanotube/poly(vinylidene fluoride) (CNT/PVDF) layer, a middle chitosan (CS) layer, and a top superhydrophobic fumed silica-chitosan (SiO2/CS) layer modified with 1H,1H,2H,2H-heptafluorodecyltrimethoxysilane (FAS). Under near-infrared (NIR) light irradiation, the LSSF quickly bent toward the CS layer with a large bending angle (>200°), high sensitivity (∼7 °C change), and great repeatability (>1000 cycles), which was attributed to the significant difference in the coefficient of thermal expansion (CTE) between CS and PVDF and the water desorption-induced volume shrinking in the CS layer. Furthermore, the LSSF also exhibited superhydrophobicity with a high water contact angle of 165° and a low water sliding angle of 2.8°. Importantly, owing to the high light absorption of CNTs, the LSSF-based biomimetic flower was able to not only bloom under NIR light exposure but also normally work when applying sunlight irradiation. Thanks to the electric conductivity and excellent water repellency, the LSSF was capable of being designed as an electric switch to remotely turn on/off the circuit even under a watery environment, and the LSSF was further successfully applied in water-droplet manipulation. The findings conceivably provided a new strategy to fabricate light stimuli-responsive superhydrophobic films for versatile applications.

Skin-inspired thermoelectric nanocoating for temperature sensing and fire safety.

Temperature sensing enables flammable materials to respond intelligently at high temperature, which is conducive to further improving their fire safety. However, it is still challenging to develop a smart nanocoating with sensitive temperature-sensing and efficient flame retardancy. Inspired by human skin, a thermoelectric flame retardant (TE-FR) nanocoating was fabricated by combining a dermis-mimicking thermoelectric (TE) layer and an epidermis-mimicking flame retardant (FR) layer. The TE-FR nanocoating exhibited accurate temperature sensing at 100-300 ℃ and repeatable fire-warning capability. When being burned, the fire-warning response time of the TE-FR nanocoating was only 2.0 s, and it retriggered the fire-warning device within 2.8 s when it was reburned. Meanwhile, the TE-FR nanocoating exhibited outstanding flame retardancy. The coated polypropylene self-extinguished in the horizontal and vertical burning tests. Besides, its peak heat release rate, total heat release, and peak smoke production rate were significantly reduced. This work proposed an ingenious strategy to fabricate smart nanocoating for temperature sensing and fire safety, which revealed an enticing prospect in the fields of fire protection, electronic skin, and temperature monitor.

Multifunctional MXene/Chitosan-Coated Cotton Fabric for Intelligent Fire Protection.

Multifunctional intelligent fireproof cotton fabrics are urgently demanded in the era of the Internet of Things. Herein, a novel high fire safety cotton fabric (denoted as MXene/CCS@CF) with temperature sensing, fire-warning, piezoresistivity, and Joule heating performance was developed by coating MXene nanosheet and carboxymethyl chitosan (CCS) via an eco-friendly layer-by-layer assembly method. Benefiting from the thermoelectric characteristic and high conductivity of MXene nanosheet, MXene/CCS@CF exhibited accurate wide-range temperature sensing performance. When being burned, it could repeatedly trigger the fire-warning system in less than 10 s. More importantly, MXene/CCS@CF showed outstanding flame retardancy because of the synergistic carbonization between MXene and CCS. The limiting oxygen index of MXene/CCS@CF was as high as 45.5%, and the char length was only 33 mm after the vertical burning test. Meanwhile, its peak heat release rate reduced more than 66%. Besides, the obtained fabric could detect a variety of human motions. Moreover, the controllable Joule heating performance enabled the fabric to be used in extreme cold weather. This work provides a facile approach to fabricating a next-generation high fire safety cotton fabric, showing promising applications in firefighting, home automation, and smart transportation.

Three-Dimensional Binary-Conductive-Network Silver Nanowires@Thiolated Graphene Foam-Based Room-Temperature Self-Healable Strain Sensor for Human Motion Detection.

A lot of attention has recently been focused on wearable strain sensors because of their promising applications in the rising areas of human motion detection, health monitoring, and smart human-machine interaction. However, the design and fabrication of self-healable strain sensors with superior overall properties including stretchability, sensitivity, response ability, stability, and durability is still a huge challenge. Herein, we report an innovative self-healable strain sensor with exceptional overall performance constructed with three-dimensional binary-conductive-network silver nanowire-coated thiolated graphene foam (AgNWs@TGF) and room-temperature self-healing functionalized polyurethane (FPU) elastomer. Taking advantage of the good ductility and continuity of the AgNWs@TGF binary structure and the excellent resilience of the FPU, the strain sensor exhibits good stretchability (up to 60% strain), high sensitivity [gauge factor (GF) of 11.8 at 60% strain and detection limit of 0.1% strain], fast response ability (response/recovery time of 40/84 ms), and exceptional durability for 800 cycles of fatigue test. Besides, the highly flexible polydimethylsiloxane chains, strong intermolecular hydrogen bonding, and dynamic exchange reaction of aromatic disulfides ensure the sensor excellent recovery property of electrical conductivity, and the GF of sensor after self-healed only increases slightly. More importantly, the sensor is successfully applied for detecting a variety of human motions including pulse beats, voice recognitions, various joint movements, and handwriting. The method for preparing room-temperature self-healable strain sensor is facile, scalable, and cost-effective. The finds provide a new perspective on fabricating new-generation high-performance and functional strain sensors for health monitoring, wearable electronics, and intelligent robots.

RIRS with Vacuum-Assisted Ureteral Access Sheath versus MPCNL for the Treatment of 2-4 cm Renal Stone.

OBJECTIVE: Comparison of outcomes between RIRS with vacuum-assisted ureteral access sheath (V-UAS) and MPCNL in the treatment of renal stone. MATERIALS AND METHODS: 28 patients with 2-4 cm renal stone were treated using RIRS with 14/16 F V-UAS. The outcomes were compared to those who underwent MPCNL with 16 F Amplatz sheath using a matched-pair analysis in a 1 : 2 scenario. Matching criteria included stone size, location and laterality, gender, age, BMI, and degree of hydronephrosis. Patients' demographics, perioperative and postoperative characteristics, complications, stone-free rate (SFR), and auxiliary procedures were compared. RESULTS: Mean operative times for the RIRS and MPCNL groups were 72.4 ± 21.3 minutes and 67.4 ± 25 minutes (P = 0.042). Postoperative pain was significantly less in the RIRS group. The initial SFR was 50% for the RIRS group and 73.2% for the MPCNL group (P = 0.035). The final SFR at postoperative three months improved to 89.3% for the RIRS group and 92.9% for the MPCNL group (P = 0.681). The auxiliary procedure rates were higher in the RIRS group (42.9% vs. 25%, P = 0.095). The overall complication rate in the RIRS group was lower, but the significant difference was not found. CONCLUSION: In the treatment of 2-4 cm renal stone, using V-UAS in RIRS can improve surgical efficiency with lower postoperative early pain scores. Comparing with MPCNL, its initial SFR was more depressed, and there is still a trend towards requiring more auxiliary procedures to achieve comparable final SFR.

Highly stretchable, transparent and room-temperature self-healable polydimethylsiloxane elastomer for bending sensor.

Highly stretchable and self-healable elastomers are attractive for a variety of applications in the fields of electrical skin and wearable devices. Herein, we proposed a simple one-pot two-step approach to synthesize room-temperature self-healable polydimethylsiloxane (PDMS) elastomers. Excess aminopropyl terminated polydimethylsiloxane was firstly reacted with isophorone diisocyanate to synthesize amino-terminated PDMS with incorporated ureido groups, followed by further reaction with terephthalaldehyde as chain extender to yield self-healing PDMS elastomers. The obtained elastomer exhibited high stretchability of 1670% and transmittance of 92%. Owing to the dynamic intermolecular hydrogen bonds, reversible imine bonds and highly flexible SiO chains, the elastomer showed excellent self-healing capability with a healing efficiency of 95% after healing at room temperature for 24 h. Even in water and artificial sweat, the healing efficiencies also reached 89% and 78%, respectively. In addition, the elastomer supported triple-layer bending sensor was fabricated with a sandwiched hydroxylated multiwalled carbon nanotubes (MWCNTs-OH) film and successfully applied for detecting human motions. Interestingly, the cut sensor was able to be recovered for working after being irradiated under sunlight for only 10 min. Our method to synthesize highly stretchable, transparent and self-healing elastomers is simple and the reaction can be carried out at room temperature, which is beneficial for the large-scale production and the further practical application in functional electronics.

Minimally Invasive Percutaneous Nephrolithotomy with a Novel Vacuum-assisted Access Sheath for obstructive calculous pyonephrosis ：A Randomized Study.

PURPOSE: To investigate the safety and efficacy of Minimally Invasive Percutaneous Nephrolithotomy (MPCNL) combined with Vacuum-assisted Access Sheath in the treatment of obstructive calculous pyonephrosis. MATERIALS AND METHODS: Seventy-six patients with obstructive calculous pyonephrosis, who were planned to receive MPCNL, were randomly divided into two groups. Group A was treated with Amplatz sheath combined with Cyberwand double probe ultrasound lithotripsy, and group B was treated with Vacuum-assisted Access Sheath (VAAS, ClearPetra, Well lead Medical) combined with holmium laser lithotripsy. The primary outcome was the operation successful rate. Other perioperative, and postoperative data such as operation time, stone free rate and complications were compared between groups. RESULTS: Single 20F access sheath was established in all cases. All patients underwent one-stage procedure. Compared with group A, group B had a higher initial stone-free rate (84.2% vs 63.1%, P= .037). The operation time of group B was 56.3 ± 19.83 min, significantly shorter than that of group A at 70.4 ± 14.83 min. The complication rate of B group was 15.8%, which was lower than that of group A (P= .035 ). Five patients (15.8 %) of group B had a postoperative fever (>38.5 ºC) (Clavien grade 2) that required additional antibiotics; whereas 8 patients (21.1 %) of group A (P= .361). There was no blood transfusion in group A, and one case in group B required transfusion. CONCLUSION: One-stage MPCNL combined with Vacuum-assisted Access Sheath and holmium laser lithotripsy is a simple, safe, effective, and ergonomically practical method for selected patients with obstructive calculous pyonephrosis.

Bioinspired Superhydrophobic Thermochromic Films with Robust Healability.

Thermochromic films with intriguing functionalities have great potential in soft actuators, heat storage devices, and interactive interface sensors. Inspired by the unique features of bird feathers (such as Nicobar pigeon, Anna hummingbird, mandarin duck, etc.), a superhydrophobic thermochromic film (STF) with robust healability is proposed for the first time through sandwiching an electric heater between a top thermochromic layer and a bottom poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) substrate. The STF exhibits fast and reversible color conversions of blue-pink-yellow under a low input power and has a superhydrophobic property with a contact angle of 155°. Furthermore, owing to the strong dynamic dipole-dipole interactions between the polar CF3 groups of flexible PVDF-HFP chains, the STF possesses a robust healing capability of structure and conductivity. By means of the temperature difference generated by the objects contacting (finger, iron, and water) as a stimulus, the STFs achieve tactile imaging and writing record with advantages of transient display, automatic erasure, and excellent reusability. Additionally, the STF-based anti-counterfeiting security labels with superhydrophobicity and three-state color switching simultaneously realize facile distinguishment and difficult forgery. The findings conceivably stand out as a new methodology to fabricate functional thermochromic materials for innovative applications.

Self-assembly of nanoencapsulated undecanoic acid on cotton fiber for thermoregulating textiles.

We herein report the preparation of phase change nanocapsules with undecanoic acid (UA) as the core and a styrene-butyl acrylate copolymer as the shell by miniemulsion polymerization using interfacial redox initiation. The morphology, particle size, thermal properties, and structure of the nanocapsules were characterized by transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. Further, the cotton fiber was dissolved in hydroxyl-functionalized ionic liquid 1-(3-chloro-2-hydroxypropyl)-3-methyl imidazolium chloride, and then the nanoencapsulated UA was immobilized on the cotton fiber by mixing the solution with the phase change nanocapsule emulsion. The desired thermoregulating fabrics were then recovered by vacuum suction filtration and drying, and their surface morphologies and thermoregulating properties were evaluated. The nanocapsules were found to be of a regular spherical shape with a diameter ranging from 90 to 110 nm, and they exhibit a phase change temperature of 29.3 °C. Finally, the prepared thermoregulating non-woven fabrics exhibited excellent thermal reliability, air permeability, and thermoregulating capability.

One-pot fabrication of superhydrophobic and flame-retardant coatings on cotton fabrics via sol-gel reaction.

Waterproof and flame-retardant fabrics are widely utilized in many fields, such as automotive interiors, indoor decorations, outdoor clothing and tents. Herein, a facile one-pot sol-gel approach was developed to construct superhydrophobic and flame-retardant (SFR) coatings on cotton fabrics. The cotton fabric was activated by O2 plasma and then immersed into the ethanol suspension containing tetraethoxysilane (TEOS), hydroxyl-terminated polydimethylsiloxane (HPDMS) and ammonium polyphosphate (APP). The hydrogen bonding interaction between APP and cellulose motivated the APP to attach to the cotton fibers during the initial stirring process. After the addition of ammonia, the in situ sol-gel reaction of TEOS and HPDMS was initiated to generate polydimethylsiloxane-silica hybrid (PDMS-silica). The micro-nano structured composite coating on cotton fabric was successfully fabricated by the PDMS-silica and APP. The SFR cotton fabric showed outstanding durability and self-cleaning ability with a water contact angle (WCA) above 160°. When exposed to fire, the SFR cotton fabric quickly charred to extinguish the fire by generating a dense intumescent char layer under the physical barrier effect of PDMS-silica and the intumescent flame-retardant effect of APP. This one-pot approach for fabricating SFR cotton fabric is simple, cost-effective and timesaving, demonstrating significant advantages in practical production.

A green approach to fabricating nacre-inspired nanocoating for super-efficiently fire-safe polymers via one-step self-assembly.

Developing a high efficient, environmental-friendly and universal fire-safe strategy for combustible polymers is crucial but challengeable. Inspired by nacre, we developed a super-efficiently fire-safe nanocoating based on carboxymethyl chitosan (CCS) and modified montmorillonite (MMT) via one-step self-assembly. The nanocoating possessed well-arranged nacre-like hierarchical microstructure, exhibiting high transparency and specific nacre-like iridescence. More importantly, the nanocoating endowed many large-scale polymer substrates, such as polyester film, cotton fabric and polyurethane foam, with super-efficient fire-safety by dip-coating or spray-coating. All the coated substrates were self-extinguished in the burning tests. Meanwhile, their heat release and smoke production were decreased remarkably. Most notably, the peak heat release rate, total heat release, peak smoke production rate and total smoke production of polyurethane foam were decreased by 84.1%, 89.4%, 84.4% and 95.2%, respectively. Additionally, no organic solvent, halogen and phosphorus element were involved, which was environmental-friendly. Our findings provide a super-efficient, economical, universal and green fabrication strategy for fire-safe polymers.

P doped MoS2 nanoplates embedded in nitrogen doped carbon nanofibers as an efficient catalyst for hydrogen evolution reaction.

Two-dimensional (2D) molybdenum sulfide (MoS2) is considered as a promising catalyst for hydrogen evolution reaction (HER), originated from its abundant hydrogen evolution active sites. However, the HER performance of MoS2 is currently hindered by the limited exposed density of the active sites and low conductivity. Herein, we report a facile and scalable electrospinning technique to fabricate 2D MoS2 nanoplates doped with phosphorus within one-dimensional nitrogen doped-carbon nanofibers (NCNFs-MoS2|P) as a highly efficient HER catalyst. The space-confined growth with the presence of NCNFs avoided the stacking and aggregation of the MoS2 nanoplates, resulting in more exposed edge sites. The introduction of phosphorus atoms further activated the surface of MoS2 and enhanced the electron transfer. The overpotential of NCNFs-MoS2|P reached 98 mV at 10 mA cm-2, exhibiting excellent HER catalytic activity. Besides, almost no decay was observed after the stability test (5000 cycles or 20 h). The density functional calculations (DFT) elucidated that the incorporation of phosphorus atoms significantly improved the electrical conductivity and decreased the H adsorption energy barrier on MoS2, leading to a high catalytic performance of NCNFs-MoS2|P.

Thiolated Graphene@Polyester Fabric-Based Multilayer Piezoresistive Pressure Sensors for Detecting Human Motion.

In the past several years, wearable pressure sensors have engendered a new surge of interest worldwide because of their important applications in the areas of health monitoring, electronic skin, and smart robots. However, it has been a great challenge to simultaneously achieve a wide pressure-sensing range and high sensitivity for the sensors until now. Herein, we proposed an innovative strategy to construct multilayer-structure piezoresistive pressure sensors with an in situ generated thiolated graphene@polyester (GSH@PET) fabric via the one-pot method. Taking advantage of the spacing among the rough fabric layers and the highly conductive GSH, the sensor realized not only a wide pressure range (0-200 kPa), but also high sensitivity (8.36 and 0.028 kPa-1 in the ranges of 0-8 and 30-200 kPa, respectively). After 500 loading-unloading cycles, the sensor still kept high sensitivity and a stable response, exhibiting great potential in long-term practical applications. Importantly, the piezoresistive pressure sensor was successfully applied to accurately detect different human behaviors including pulse, body motion, and voice recognition. Additionally, the sensing network integrated by the sensors also realized mapping and identifying spatial pressure distribution. Our method to construct the wide-range and high-sensitivity piezoresistive pressure sensor is facile, cost-effective, and available for mass production. The findings provide a new direction to fabricate the new-generation high-performance sensors for healthcare, interactive wearable devices, electronic skin, and smart robots.

Synthesis of Zirconium-Containing Polyhedral Oligometallasilsesquioxane as an Efficient Thermal Stabilizer for Silicone Rubber.

Free radicals play a negative role during the thermal degradation of silicone rubber (SR). Quenching free radicals is proposed to be an efficient way to improve the thermal-oxidative stability of SR. In this work, a novel zirconium-containing polyhedral oligometallasilsesquioxane (Zr-POSS) with free-radical quenching capability was synthesized and characterized. The incorporation of Zr-POSS effectively improved the thermal-oxidative stability of SR. The T5 (temperature at 5% weight loss) of SR/Zr-POSS significantly increased by 31.7 °C when compared to the unmodified SR. Notably, after aging 12 h at 280 °C, SR/Zr-POSS was still retaining about 65%, 60%, 75%, and 100% of the tensile strength, tear strength, elongation at break, and hardness before aging, respectively, while the mechanical properties of the unmodified SR were significantly decreased. The possible mechanism of Zr-POSS for improving the thermal-oxidative stability of SR was intensively studied and it was revealed that the POSS structure could act as a limiting point to suppress the random scission reaction of backbone. Furthermore, Zr could quench the free radicals by its empty orbital and transformation of valence states. Therefore, it effectively suppressed the thermal-oxidative degradation and crosslinking reaction of the side chains.