In light of the accelerated advancement of smart wearable technology, there has been a considerable focus on the development of strain sensors that can withstand harsh environments and exhibit superior motion detection capabilities. In this study, hydrophobic polyurethanes containing pentaerythritol dioleate (PD) and poly (dimethylsiloxane), bis (hydroxyalky) terminated (HO-PDMS-OH) chain segments were synthesized. It was then utilized for the fabrication of superhydrophobic membrane-based strain sensor by electrospinning and decorated with multiwall carbon nanotube (CNTs) via suction filtration. The resulting strain sensor exhibited a broad sensing range (0 - 428.6%) and a high sensitivity (GF = 4546.5), while demonstrating a stable electromechanical performance over 10,000 load-unload cycles in the strain range from 0 to 50%. The sensor also had a static water contact angle (WCA) of 154.6 degrees indicating of the superhydrophobicity and displayed a high resistance to acid, alkali and salt solutions. Moreover, the strain sensor attached on finger can output high resolution electrical signal in water demonstrating excellent work stability in high humidity. This study offers valuable insights into the development of wearable electronic devices for healthcare monitoring in harsh environments, particularly within the field of advanced materials.

Isobutylene-isoprene rubber (IIR) is widely used in medical seals and inner tubes due to its remarkable gas barrier properties. However, the absence of polar groups and limited interfacial affinity toward inorganic fillers limit further improvement in its gas barrier performance. Herein, IIR was epoxidized using m-chloroperoxybenzoic acid to obtain epoxidized IIR (EIIR). Graphene oxide (GO) was modified using gamma-aminopropyltriethoxysilane and sodium polystyrene sulfonate (PSS) to yield functionalized GO (PSS-mGO). The PSSmGO was further incorporated into EIIR via solution blending, and the resulting PSS-mGO/EIIR compound was blended with IIR to obtain PSS-mGO/EIIR/IIR composites. The inclusion of EIIR into the IIR matrix introduced epoxy-functionalized segments into the composite, thereby enhancing intermolecular interactions and restricting segmental relaxation. Consequently, the nitrogen permeability of the EIIR/IIR composites decreased by 42.1% relative to that of the IIR composite at an EIIR/IIR mass ratio of 1:9. Further incorporation of PSS-mGO improved filler dispersion and formed a well-developed filler network. A more tortuous diffusion pathway for gas molecules was created, reducing nitrogen permeability by up to 52.2% relative to that of the IIR composite. The results demonstrate that combining EIIR and functionalized GO is an effective strategy for improving the gas barrier performance of IIR composites.

The heightened development of power network infrastructure has necessitated enhanced performance requirements from rubber composites used in transmission lines. Ethylene propylene diene monomer (EPDM) rubber is the primary matrix component in many damping spacer rubber composites for these applications. However, due to flexible molecular chains, nonpolar structure, and poor compatibility with polar nano-fillers, EPDM exhibits poor mechanical properties and unsatisfactory damping properties. This study investigated the modification of EPDM molecular chains by epoxidation to produce epoxidised ethylene propylene diene monomer (EEPDM) rubber. Subsequently, EEPDM was compounded with EPDM to create EEPDM/EPDM composites. The introduction of epoxy groups in EEPDM enhanced intermolecular interactions within the rubber composites, facilitating energy dissipation and improving damping performance under external cyclic loads through polar intermolecular interactions. Furthermore, the interaction between epoxy groups and silica improved silica dispersion within the composite. EEPDM/EPDM composites in a 40/60 ratio demonstrated significant improvements over EPDM composites, with an increase of 173.8% in 300% Modulus and 23.2% improvement in tensile strength. Additionally, elevated loss factors were observed within the 0°C–40°C temperature range for EEPDM/EPDM composites, indicating an enhanced damping performance.

Developing stretchable strain sensors with multi-mode sensing capabilities is crucial to meeting the growing demand for electronic devices. In this study, a stretchable dual-mode sensor based on a core-sheath structured composite fiber containing a magnetic sensitive magnetorheological fluid (MRF) core encapsulated in an electrically conductive polystyrene-ethylene-butylene-styrene (SEBS)/carbon nanotubes (CNTs) sheath is proposed. The SEBS/CNTs/MRF (SCM) fiber could sense tensile strains of up to 148% and output stable signals during 2000 repeated tensile cycles. The SCM fiber could respond to magnetic field stimuli with corresponding electrical signal variations over different magnetic field intensities. Moreover, the SCM fiber exhibited noticeable magnetorheological effect with a magneto-induced modulus of 1.06 MPa when subjected to a magnetic field density of 970 mT. With excellent performances in human motion monitoring and magnetic actuation for cargo transportation, the SCM fiber showed great potential in contact/non-contact sensors and actuators that can be used in new generation intelligent devices.

With the development of new energy vehicles, vehicle weight and the influence of heightened frequency of starting and braking on tire properties are much higher than those for traditional petrol/diesel fuel vehicles, leading to a requirement for much lower rolling resistance and higher abrasion resistance of tire tread rubber. In this research, graphene oxide (GO) was treated by maleic anhydride-grafted polyisoprene liquid rubber (MLR) to form MLR-GO. MLR-GO was further compounded with natural rubber (NR) to obtain MLR-GO/NR composites by green latex compounding and subsequent flocculation. A liquid rubber interfacial layer on the surface of GO increased the spacing between GO lamellae, and improved the dispersion of GO in NR. Due to extensive stretching of molecular chains of MLR and NR in the liquid phase, MLR molecular chains on the surface of MLRGO were entangled with NR molecules. Moreover, elastic interfaces on the surface of GO were created during the subsequent high-temperature vulcanization process, leading to a strengthening of the interfaces between GO and NR and interfacial friction in the rubber composite was reduced. Results showed the MLR-GO/NR composites had excellent overall performance when the ratio of MLR to GO was 2.5:1. The rolling resistance and temperature rise during dynamic cycling of the 2.5 MLR-GO/NR composites were superior by 10.4 % and 5.2 degrees C, respectively, and the abrasion resistance was improved by 35.2 %, when compared with the NR composites without GO.

One-dimensional fibrous dielectric elastomers (DEs) can experience uniaxial displacement when electrical signals are applied to them and in consequence, they can imitate the contraction and elongation of artificial muscles. However, it is still a challenge to obtain fibrous DEs possessing high electric field induced deformations. In this work, the fabrication of high dielectric lanthanum-doped barium titanate (La-BTO) encapsulated multiwall carbon nanotubes (MWCNTs) (La-BTO@MWCNTs) incorporated in styrene-ethylene-butylene-styrene copolymer (SEBS) is described. The outcome of this process is a DE with excellent electromechanical performance. The results obtained from testing demonstrated that La doping effectively enhanced the dielectric constant of La-BTO@MWCNTs. A high dielectric constant of 2.77 was achieved for a low amount of La doping (the molar ratio of Ba:La was 100:1). The DE actuator (DEA) containing 2.0 % La-BTO@MWCNTs exhibited a maximum actuated longitudinal strain of 23.12 % and a maximum output force of 25.85 mN for an electric field of 50 V/ mu m. Furthermore, the SEBS/La-BTO@MWCNTs based DEA provided reliable working stability over 100 voltage cycles from 0 to 5 kV. This text describes a simple and effective new method for developing high performance DEAs to realize applications in the fields of soft robotics, biomedical devices and adaptive systems.

Wearable flexible electronics have garnered significant research interest due to their extensive applications in human motion sensing, health monitoring, and human-computer interaction. Among these, flexible strain sensors that effectively convert external stimuli into electrical signals are crucial for wearable electronic devices. Bacterial cellulose (BC), characterized by its rich hydroxyl groups and unique three-dimensional porous network structure, exhibits excellent biocompatibility, flexibility, and mechanical strength, making it an ideal candidate for high-performance wearable strain sensors as a base material or reinforcing agent. In recent years, numerous studies have focused on BC-based strain sensors, highlighting the urgent need for a comprehensive review of the latest research progress in this field. This review delves into the preparation methods and key properties of bacterial cellulose, categorizing the advancements in BC-based wearable strain sensors according to the type of conductive fillers used. Furthermore, it analyzes the role of BC in enhancing the critical performance metrics of strain sensors, summarizing its contributions to sensitivity, stretchability, linearity, and dynamic durability. Considering the unique three-dimensional porous structure of BC, high mechanical strength, and excellent flexibility, it holds vast potential for applications in wearable strain sensors, including motion detection, health monitoring, and human-computer interaction.

With concern over the environment increasingly important globally, there is an imperative for the development of more sustainable electronic materials. Flexible strain sensors, capable of translating mechanical deformation into electrical signals, have garnered significant interest in applications such as healthcare monitoring and soft robotics. In this study, a biodegradable fiber-based flexible strain sensor with excellent electromechanical properties was developed using custom polyurethanes modified with polylactic acid and silicone (Si-BTPU) blended with carbon nanotubes (CNTs) via environmentally friendly melt spinning technology. The results revealed that the Si-BTPU exhibited biodegradability, with a degradation rate of 5.7 % after just 4 weeks. Notably, the obtained strain sensor demonstrated an impressive sensing range of 0-395 %, high sensitivity (gauge factor GF = 42) and a low detection limit of less than 2 %, while maintaining stable electromechanical performance over 10,000 tensile loading-unloading cycles. Furthermore, human epidermal fibroblasts (HDFs) displayed strong adhesion to and proliferation on the strain sensor, indicating its suitability for skin surface applications. This research provides valuable insights into the advancement of wearable electronic devices for healthcare monitoring within the realm of advanced materials.

To avoid harm to humans and devices, developing electromagnetic interference (EMI) shielding materials possessing high shielding efficiency and enhanced electromagnetic (EM) wave absorption properties is of fundamental importance. Preventing threats caused by EMI and reducing the secondary pollution of EM waves are critical requirements for materials. In the research described here, composites of Ag nanoparticles coated with poly p-phenylene terephthalamide (PPTA) nonwoven and Fe3O4 decorated MXene nanosheets were prepared by electroless silver plating and Fe3O4-MXene deposition. The top and bottom layers of the composites were Fe3O4 nanoparticle-decorated MXene nanosheets and silicone rubber, while the middle layer consisted of a Ag nanoparticle-coated PPTA nonwoven fabric. The formation of the sandwich structure, the electromagnetic compounding, and the porous structure of the PPTA nonwoven fabric coated with Ag nanoparticles endowed the composites with excellent EMI shielding properties. An EMI shielding effectiveness of 89.92 dB was achieved in the frequency range of 8.2-12.4 GHz. The absorption coefficient A of the composites reached 0.203, which was noticeably enhanced compared with 0.013 of Ag nanoparticle-coated PPTA nonwoven fabric.

Polydimethylsiloxane has the characteristics of low-temperature flexibility and excellent aging resistance. However, high molecule mobility and weak interactions between PDMS molecules result in poor mechanical strength and deficient gas barrier properties of PDMS composites. Herein, diamino-polydimethylsiloxane (PDMS) was reacted with 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO) to form urea-carbamate functionalized PDMS (MDI-PDMS-BDO) with different hard segment contents. Furthermore, the modified graphene oxide (iGO) was obtained by the reaction between graphene oxide (GO) and MDI. iGO was further introduced into the functionalized PDMS to prepare iGO/urethane-urea functionalized PDMS composites (iGO/MDI-PDMS-BDO). An ordered structure was formed by the hard segments of the MDI-PDMS-BDO functionalized PDMS. A strong urea-based interface was also obtained between iGO and functionalized PDMS. iGO became the cross-linking center in the iGO/MDI-PDMS-BDO composites. Due to the ordered structure of hard segments and the iGO network formed in the PDMS composite with only 0.07 wt% iGO, the tensile strength and gas barrier properties of the iGO/MDI-PDMS-BDO composite were increased by 18 times and 64.27%, respectively, compared with pure PDMS.

The high elasticity and excellent gas barrier properties of rubber composites make them irreplaceable in the field of sealing. Constructing a complicated barrier network to reduce free volume is crucial to improving gas barrier properties. In this research, liquid acrylonitrile-butadiene rubber/γ-Methacryloxypropyl trimethoxy silane (KH570) modified graphene oxide/butyl rubber composites (LNBR/KGO/IIR) were fabricated. A KGO lamellar network was constructed to resist gas diffusion in the IIR matrix. Meanwhile, LNBR macromolecules further occupied the free volume inside the IIR composites, thereby maximizing the retardation of the path of small molecule gas permeation. The modification of GO by KH570 was successfully demonstrated through FTIR and XRD. The grafting rate of KH570 was calculated to be approximately 71.4%. KGO was well dispersed in IIR due to emulsion compounding and the formation of lamellar networks. The 300% modulus, tensile strength and tear strength of KGO/IIR were improved by 43.5%, 39.1% and 14.8%, respectively, compared to those of the IIR composite. In addition, the introduction of LNBR resulted in a 44.2% improvement in the gas barrier performance of nitrogen permeability relative to the original IIR composite.

Dielectric elastomers (DEs), have attracted interest because they can replicate the behavior of muscles. They can change shape when subjected to an electric field. A novel DE is proposed in this study that incorporates silicon carbide (SiC) nanowires into silicone rubber (SR). The nanowires were propagated using polycarbosilane via a chemical vapor reaction (CVR). A boronate polymer was employed to promote compatibility between SR and SiC nanowires which modified the nanowire surfaces, leveraging a strong adhesive quality of the catechol moiety. Electrohydrodynamic (EHD) inkjet printing was then used to form the DEs into various shapes. These DEs had substantial dielectric constants of the order of 4.46. Significantly, one of the DEs achieved the highest actuated area strain of 20.36% in an electric field of 16.5 V/mu m, demonstrating excellent driving performance. Furthermore, when used the fabricated DEs showed pronounced long-term stability, meaning they are capable of finding applications in artificial intelligence, biomimetics, aerospace, and other disciplines.Highlights The SiC nanowires were obtained through a chemical vapor reaction. A boronate polymer with catechol moiety was used to modify the SiC nanowires. DEs were formed various shapes by inkjet printing. DEs achieved very large actuated strains of up to 20.36% at 16.5 V/mu m. The preparation schematic of dielectric elastomers based on silicone carbide nanowire and silicone rubber (SR). image

Dielectric elastomers (DEs) are smart materials that can transform electrical energy to mechanical energy. Compared with commonly reported two-dimensional membrane-structured DE actuators (DEAs) that can generate biaxial displacement, fiber-based DEAs are able to generate uniaxial displacement through internal contraction or relaxation forces, mimicking the working mechanism of human muscles. In this work, high-dielectric barium titanate (BTO)-encapsuled carboxylated multiwalled carbon nanotubes (MWCNTs) (BTO@MWCNTs) were prepared and incorporated into a styrene-ethylene-butylene-styrene copolymer (SEBS) to fabricate flexible hollow fiber-based DEs through coaxial wet spinning. By filling the hollow fiber with liquid metal and coating the surface with a flexible carbon grease electrode, a kind of hollow fiber-based actuator (HFDEA) was acquired. The HFDEA achieved a 19.76% actuated elongation at an excitation electric field strength of approximately 49 V/mu m and exhibited reliable durability in 100 repeated actuation tests. The fabricated HFDEA has great application potential in the artificial muscle field.

In order to fulfill the demands for degradability, a broad working range, and heightened sensitivity in flexible sensors, biodegradable polyurethane (BTPU) was synthesized and combined with CNTs to produce BTPU/CNTs coated cotton fabric using an ultrasonic-assisted inkjet printing process. The synthesized BTPU displayed a capacity for degradation in a phosphate buffered saline solution, resulting in a weight loss of 25 % after 12 weeks of degradation. The BTPU/CNTs coated cotton fabric sensor achieved an extensive strain sensing range of 0-137.5 %, characterized by high linearity and a notable sensitivity (gauge factor (GF) of 126.8). Notably, it demonstrated a low strain detection limit (1 %), rapid response (within 280 ms), and robust durability, enabling precise monitoring of both large and subtle human body movements such as finger, wrist, neck, and knee bending, as well as swallowing. Moreover, the BTPU/CNTs coated cotton fabric exhibited favorable biocompatibility with human epidermis, enabling potential applications as wearable skin-contact sensors. This work provides insight into the development of degradable and high sensing performance sensors suitable for applications in electronic skins and health monitoring devices.

The hazard to the ecosystem caused by rubber microparticles generated from tire abrasion has been a constant concern. Therefore, to protect this ecosystem, the development of a tire tread with high abrasion resistance is especially significant. Herein, gamma-aminopropyltriethoxysilane (APTES) was used to modify graphene oxide (GO) and silica (SiO2) to obtain GO and SiO2 with positive charges (NG and NS). Furthermore, NG and NS were electrostatically self-assembled by using maleic anhydride (MAH) hydrolysis, thereby obtaining composite particles (NG-NS) with "bridged structures". Also, the NG-NS/styrene butadiene rubber (SBR) compounds pos-sessing fine dispersion of NG-NS were prepared by the aqueous compounding method. During the crosslinking process, the vinyl groups in NG-NS reacted with the vinyl groups of the SBR molecule chains, thus forming strong chemical interfacial interactions between the NG-NS and rubber macromolecules. Compared with an SiO2/SBR composite, the 300 % modulus, tensile strength, abrasion resistance of the NG-NS/SBR composite were improved by 125 %, 122 %, 83.3 %, respectively. Compared with a GO/SiO2/SBR composite, heat build-up in the NG-NS/ SBR was decreased by 8.2 degrees C.

Rapidly developments in international transportation inevitably lead to an increase in the consumption of energy and resources. Minimizing the rolling resistance of tires in this scenario is a pressing challenge. To lower the rolling resistance of tires, enhancing the interaction between fillers and rubber molecules while improving the dispersion of fillers are required to reduce the internal mutual friction and viscous loss of rubber composites. In this study, graphene oxide (GO) was modified using γ-mercaptopropyltrimethoxysilane (MPTMS) with thiol groups. A modified GO/natural rubber (MGO/NR) masterbatch with a fine dispersion of MGO was then introduced into solution-polymerized styrene butadiene rubber (SSBR) to create an MGO/SiO2/SSBR composite. During the crosslinking process at high temperatures, a strong chemical interface interaction between the MGO and rubber molecules was formed by the thiol-vinyl click reaction. The MGO sheets also act as crosslinks to enhance the crosslinking network. The results showed that the rolling resistance of the MGO SiO2/SSBR composite was superior by 19.4% and the energy loss was reduced by 15.7% compared with that of the base SiO2/SSBR composite. Strikingly, the wear performance and wet skid resistance improved by 19% and 17.3%, respectively. These results showed a strong interface that not only improved rolling resistance performance but also contributed to balancing the "magic triangle" (the combination of wear resistance, fuel efficiency, and traction) properties of tires.

Flexible strain sensors have become a key component of intelligent wearable electronics. However, the fabrication of strain sensors with wide workable strain ranges and high sensitivity remains a great challenge. Additionally, the rapid development of polymer composites based strain sensors has produced a large amount of e-waste. Therefore, the development of strain sensors with wide strain sensing ranges and high sensitivity based on degradable materials is necessary. In this work, a silicone blocked polyurethane (Si-BPU) with high stretchability and degradability was synthesized and composited with carbon nanotubes (CNTs) to fabricate fibrous strain sensors. The synthesized 0.5% Si-BPU exhibited good biodegradability with a weight loss of 16.47% in 42 days. The Si-BPU/12CNTs fiber based strain sensor achieved a sensing range of 0%–353.3% strain, gauge factor (GF) of 206.3 at 250% strain and of 4,513.2 at 353.3% strain, and reliable stability under 10,000 repeated stretching-releasing cycles. Moreover, the Si-BPU/12CNTs strain sensor showed rapid response time (< 163 ms) and was capable of monitoring various human body movements (elbow bending, finger bending, breath, and swallow). In consequence, this work provides a new and effective strategy for the development of sustainable wearable electronic devices.

An elastic masterbatch and elastic melt blown nonwovens are prepared based successively on styrene-ethylene/butylene-styrene (SEBS) and polypropylene (PP) blend. The phase separation morphology, rheological properties and crystal structure of the elastic masterbatch are investigated. The results show that a compatible and stable structure is obtained in molten SEBS and PP blend with excellent mobility in the temperature range of 210-230 degrees C. The crystallization of PP slows down resulting in a finer structure due to the restriction of the SEBS network structure with rarely change of crystalline structure. The relationship between process parameters and properties of the elastic nonwoven is also studied in detail. Air pressure and die to collector distance (DCD) have discernible effects on fiber diameter and bonding between fibers, further influencing the performances of nonwovens including porosity, tensile strength and elastic recovery. Elastic recovery is shown to be significantly more affected by DCD than by air pressure.

Magnetorheological elastomers (MREs) are smart materials whose mechanical properties can quickly respond to changes in the external magnetic field. This phenomenon is known as the magnetorheological (MR) effect and is the key to the application of magnetorheological elastomers. Previous studies have found that the interface between magnetic particles and elastomers is a critical factor that influencing the MR effect of MREs. To improve the interfacial interaction between silicone rubber (SR) and carbonyl iron (CI) particles, in the MREs considered in this work, CI particles were subjected to surface modification through polydopamine (PDA) deposition and n-dodecyltrimethoxysilane (DTMS) grafting. X-ray photoelectron spectroscopy (XPS), scanning electron micro-scopy (SEM) and transmission electron microscopy (TEM) confirmed the successful deposition of PDA@DTMS coating layer with a thickness of about 30.6 nm. The tensile strength of anisotropic MREs increased by 31.5% after surface modification of CI particles. The study of magnetic field induced changes in viscoelastic properties showed that CI-PDA@DTMS based MREs exhibited a superior MR effect to the CI-based MREs.

This paper discusses the development of wearable flexible textile-based strain sensors for monitoring multiple human motions.