Styrene Isoprene Research Articles

Chemiluminescence-based evaluation of styrene block copolymers’ recyclability

The study presents the chemiluminescence based (CL) evaluation of the recyclability of linear styrene block copolymers. This analysis can provide insight into the material’s degradation state and predict its suitability for further recycling cycles, helping to avoid unnecessary energy consumption during processing.The thermal stability of four similar copolymer structures − styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) copolymers with different styrene/butadiene ratios, and styrene-ethylene-butadiene-styrene (SEBS) − was studied using isothermal and non-isothermal chemiluminescence (CL). The activation energies for oxidative degradation were calculated based on oxidation induction times indicated by the CL intensities evolution. The results, which highlight the influence of molecular structure on stability under aging conditions, as presented by the calculated for the activation energy (kJ mol−1), show the following sequence: SBS (styrene 30%) (117 kJ mol−1) ≈ SIS 120 (kJ mol−1) < SBS (styrene 40%) (176 kJ mol−1) < SEBS (180 kJ mol−1). The CL data were correlated with infrared (IR) spectroscopy and differential scanning calorimetry (DSC) data, providing a comprehensive understanding of the thermal stability and degradation mechanisms during recycling proces. The sequence of the composing units determines the degradation process, with weaker points predominantly attacked in the linear moieties of isoprene, butadiene, and vinyl segments. The experimental data indicate that SIS and SBS (30% styrene) copolymers degrade the fastest likely due to the rapid accumulation of hydroperoxide radicals. The SEBS copolymer also experiences significant degradation, but this occurs at higher temperatures (above 220 ⁰C) and progresses more gradually once it begins. In contrast, the SBS copolymer with 40% styrene content degrades more slowly and exhibits minimal mass loss, primarily due to the formation of less reactive keto degradation products.

Replacing the Gallium Oxide Shell with Conductive Ag: Toward a Printable and Recyclable Composite for Highly Stretchable Electronics, Electromagnetic Shielding, and Thermal Interfaces.

Liquid metal (LM)-based composites hold promise for soft electronics due to their high conductivity and fluidic nature. However, the presence of α-Ga2O3 and GaOOH layers around LM droplets impairs conductivity and performance. We tackle this issue by replacing the oxide layer with conductive silver (Ag) using an ultrasonic-assisted galvanic replacement reaction. The Ag-coated nanoparticles form aggregated, porous microparticles that are mixed with styrene-isoprene-styrene (SIS) polymers, resulting in a digitally printable composite with superior electrical conductivity and electromechanical properties compared to conventional fillers. Adding more LM enhances these properties further. The composite achieves EMI shielding effectiveness (SE) exceeding 75 dB in the X-band frequency range, even at 200% strain, meeting stringent military and medical standards. It is applicable in wireless communications and Bluetooth signal blocking and as a thermal interface material (TIM). Additionally, we highlight its recyclability using a biodegradable solvent, underscoring its eco-friendly potential. This composite represents a significant advancement in stretchable electronics and EMI shielding, with implications for wearable and bioelectronic applications.

Effect of Fluid Paraffin on the Formulation Properties of Pressure Sensitive Adhesive Formulations Containing Diclofenac Sodium.

Understanding the relationship between the release characteristics of the active ingredient in the tape formulation and the pharmaceutical characteristics of the adhesive layer can optimize therapeutic efficacy and improve patient adherence. This study aimed to clarify the effect of liquid paraffine (LP)/styrene-isoprene-styrene (SIS) triblock copolymer ratio on pressure-sensitive adhesive (PSA) formulation properties, such as adhesive properties and drug release, with a certain amount of diclofenac sodium (DFS) and tackifier. The effects of changes in PSA composition in DFS-containing tape formulations on adhesive and drug release properties were evaluated. The viscoelasticity results showed rigid gel-like behavior at low angular frequencies regardless of the LP/SIS ratio, and deformable gel-like behavior at high angular frequencies, with a maximum plasticizing effect of LP up to an LP/SIS ratio of 3.7. The peel adhesion test results showed that peel adhesion was not affected, but indicated a decreasing trend by increasing the LP/SIS ratio in the presence of DFS. Drug release test results showed that DFS release increased up to 24h for LP/SIS ratios of up to 3.7, but decreased when the LP/SIS ratio was 6. The results of the drug permeation tests were similar to those of the drug release tests. In conclusion, it is possible to change the drug release properties by changing the amount of LP in the tape formulation; however, no definitive correlation was found between the adhesive and drug release properties.

Enhancing Asphalt Performance: The Combined Influence of Trinidad Lake Asphalt (TLA) and Styrene–Isoprene–Styrene (SIS) on PG 64-22 Binder

Enhancing Asphalt Performance: The Combined Influence of Trinidad Lake Asphalt (TLA) and Styrene–Isoprene–Styrene (SIS) on PG 64-22 Binder

Laboratory Evaluation of Storage Stability for Asphalt Binder Modified with Crumb Rubber and Styrene-Isoprene-Styrene Depending on Evaluation Factors and Blending Condition.

Modified asphalt binders are still considered important in asphalt pavement. However, the comprehensive use of various modifiers is limited due to storage stability issues. Moreover, there is a scarcity of detailed analyses regarding the degree of separation for asphalt binders among each method despite the utilization of various methods to assess the storage stability of binders. Therefore, a comprehensive analysis was conducted to assess the storage stability of asphalt binder modified with a crumb rubber modifier (CRM) and styrene-isoprene-styrene (SIS), utilizing five evaluation factors following the ASTM D7173 guidelines based on four mixing methods (A: high-shear mixing method, B: low-speed agitating method, C: high-shear mixing method + low mixing method, D: low-speed agitating method + low mixing method). To produce the modified asphalt binder, the proportions of the CRM were 5% and 10% for each binder, and 10% SIS was added to all binders. The results in this study convey that (1) the addition of the modifier led to an increase in G*/sin δ with different mixing methods, but using mixing methods (C and D) for a relatively long time resulted in a lower G*/sin δ, indicating suboptimal performance; (2) through the multiple stress creep recovery (MSCR), rheological properties of Jnr and % rec exhibited trends similar to G*/sin δ evaluation, highlighting an improved elastic recovery with a higher modifier content; (3) storage stability assessment revealed consistent trends in high-shear mixing groups (A and C), while low-speed mixing groups (B and D) exhibited an elevated separation index (SI), suggesting a sensitivity to modification conditions; (4) evaluation using the MSCR method indicated that % rec with a 3.2 kPa load is effective for the sensitive assessment of binder storage stability and Jnr showed a limited sensitivity across varying loads, advocating for % rec for precise evaluation; and (5) despite permitting various tests, achieving consistent results remains challenging. Future research should explore diverse modifiers and optimal evaluation methods to enhance knowledge of binder behavior and separation dynamics.

A Selective-Response Hypersensitive Bio-Inspired Strain Sensor Enabled by Hysteresis Effect and Parallel Through-Slits Structures

HighlightsA bio-inspired flexible strain sensor with hypersensitivity and highly selective frequency response is prepared by styrene–isoprene–styrene combined with monolayer graphene.Benefiting from the structural design inspired by nature and hysteresis of viscoelastic materials, bio-inspired structures, and original materials' properties complement each other.The frequency recognition resolution of bio-inspired flexible strain sensor reaches 0.2 Hz, making it ideal for human–computer interaction and mechanical equipment health inspection.

Ultra‐stretchable thermoplastic elastomeric materials based on styrene–isoprene–styrene triblock copolymer: Influence of calcium copper titanate on mechanical and dielectric properties

AbstractConventional charge storage devices made of ceramic materials have limited deformability and configurability due to their extreme stiffness. The high demand for compliant dielectrics has led researchers to look beyond conventional ceramics, despite their very high dielectric properties. In this work, a mechanically robust, highly‐flexible and ultra‐stretchable thermoplastic elastomeric material with dielectric characteristics has been fabricated by introducing calcium copper titanate [CaCu3Ti4O12] (CCTO) dielectric material onto macromolecular chains of styrene–isoprene–styrene (SIS) triblock copolymer via a solution‐based polymer processing technique. CCTO powders have been synthesized using sol–gel technique. The resulting composite is ultra‐stretchable with strain at break of ~3200% and has high dielectric permittivity of ~10. High dielectric property is attributed to the well‐dispersed dielectric CCTO fillers within the SIS matrix, which provide sites for interfacial polarization and space charge accumulation. The influence of CCTO on dielectric properties has also been validated using the modified Cole–Cole model.

Direct ink writing‐based additive manufacturing of styrene‐isoprene‐styrene block copolymer

AbstractThermoplastic elastomer (TPE) is a hybrid polymeric material with immense potential for industrial application due to its unique elasticity, processability, and excellent mechanical properties. However, 3D printing of TPEs using fused deposition modeling (FDM) is challenging due to their poor layer coalescence, high melt viscosity, and weak column strength. In the present work, styrene‐isoprene‐styrene (SIS) block copolymer, a commercially available TPE material, was successfully 3D printed using a direct ink writing (DIW)‐based additive manufacturing process to enhance its design flexibility. The rheology of the prepared inks has a great influence on the printability, layer formability, and resolution of the 3D printed parts. Hansen's solubility criteria were used exclusively, to investigate the most suitable solvent to prepare the inks for the DIW technique, implying better solubility of toluene than THF. This is in line with experimental results that the 3D printed specimens from SIS/toluene inks demonstrate higher stretchability, elastic modulus and tensile strength over the 3D printed specimens from the SIS/THF inks. It has been shown that the selection of a suitable ink and the optimum level of SIS concentration is essential for the successful fabrication of parts using DIW to make them suitable for end use.Highlights The DIW process has been investigated for 3D printing of SIS block copolymers. The rheology of the developed inks has a great influence on printability and layer formability. The 3D printed samples showed high elongation at break, elastic modulus, and tensile strength.

Laboratory Evaluation of High-Temperature Properties of Recycled PMA Binders

Various environmentally friendly additives have been used to mitigate significant damage, such as plastic deformation and cracking, in asphalt pavements over the long term. Despite the existence of research demonstrating the efficacy of the materials for asphalt mixture, there has been a lack of studies focusing on the recycling of modified asphalt binders. Therefore, this study conveys the laboratory evaluation of the high-temperature properties of 12 recycled polymer-modified asphalt (PMA) binders as basic research. The data evaluation was carried out using crumb rubber modifier (CRM), styrene-butadiene-styrene (SBS), and styrene-isoprene-styrene (SIS) modified binders, depending on their recycled binders. To assess the properties of each binder, the viscosity and viscoelasticity were measured. Overall, the results of this study revealed that (1) an increasing trend for the viscosity of all asphalt binders was seen as the recycled binder was added and showed their characteristics depending on modifiers; (2) the tendency for using each modified binder in the original and rolling thin-film oven (RTFO) condition appeared for modifiers to have their properties when reusing them; (3) from the Jnr and %rec values, each property of modifiers kept its inherent characteristics, but a potential limit was seen in that a styrene block copolymer was mainly effective on this test method. To sum up, modifiers in asphalt mixture can have their unique properties even after reusing them in recycled asphalt mixture. Therefore, it is recommended that modifiers in asphalt mixture are considered as a potential factor in utilizing reclaimed asphalt pavement (RAP).

Characterization of Sustainable Asphalt Binders Modified with Styrene–Isoprene–Styrene (SIS) and Processed Oil

The current study aims to evaluate the viscosity and rheological properties of PG 64-22 modified with Styrene–Isoprene–Styrene (SIS) and Processed Oil (PO) to enhance asphalt binder properties. Performance properties were measured at high, intermediate, and low temperatures. PG 64-22 was blended with SIS and Processed Oil at three levels (5%, 10%, and 15% by weight of binder) and two concentrations (6% and 12% by weight of binder), respectively. Modified binders underwent two short and long artificial aging processes, through the spinning of the thin film in an RTFO oven and a pressure aging vessel (PAV). The Superpave binder evaluations were carried out using a rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR). According to the findings of the research, the addition of SIS caused higher values of viscosity, but when co-modified with processed oil, there was a substantial decrease in viscosity values. As a result, workability was improved. (1) It was observed that a greater reduction in viscosity was achieved when the processed oil was present at a higher concentration at 135 °C compared to a lower concentration. (2) The study showed that the incorporation of processed oil led to a reduction in rutting performance of the asphalt binder. However, the addition of SIS resulted in a notable enhancement of rutting resistance. (3) The role of processed oil as co-modifier at concentrations of 6% and 12% caused significant decreases in G*sin δ, based on the susceptibility of asphalt molecules to accept oil molecules in their network links. (4) The extracted measurements from the BBR tests indicated that modification with SIS and PO improved the low-temperature cracking resistance significantly. Comparison of asphalt binders modified with 6% and 12% PO and the same SIS content showed significant changes in modification with 12% PO rather than 6%.

Effect of SIS block copolymers on damping properties of natural rubber/AO-80 and the performance enhancement mechanism: experimental study and molecular dynamics simulation

Natural rubber/blocked phenol/styrene-isoprene block copolymer (NR/AO-80/SIS) composites were prepared by using hindered phenolic polar small molecules (AO-80) and styrene isoprene block copolymer (SIS) as damping performance-enhancing components and (NR) as rubber substrate to overcome the problems of narrow effective damping temperature range, unsatisfactory damping effect and subpar mechanical properties in NR/AO-80 rubber applications.The effects of SIS and AO-80 on the morphology, structure, mechanical properties, aging resistance, and damping properties of the NR/AO-80/SIS composite were investigated. Molecular dynamics simulations (MD) were employed to investigate the intermolecular forces, and interaction mechanisms of the rubber composites. SIS exhibited compatibility with the NR/AO-80 matrix and can significantly enhanced the mechanical, aging, and damping properties of the NR/AO-80 matrix. The effective damping temperature range can be extended to a maximum of 114.5 °C, demonstrating its notable improvement to the damping performance of NR/AO-80. The primary mechanisms of enhancing damping performance involve the more van der Waals forces, electrostatic interactions in NR/AO-80/SIS composites,which is beneficial for increasing the internal friction of rubber and improving the damping performance of NR/AO-80 /SIS.

Evaluation of rheological behavior of asphalt mixtures modified with triblock polymers grafted maleic anhydride and montmorillonite clay

AbstractThis work presents an investigation of the incorporation of maleic anhydride (MAH)‐grafted triblock copolymers and montmorillonite clay (Mt) as modifiers of asphalt. A series of unmodified copolymers styrene‐butadiene‐styrene (SBS), styrene‐isoprene‐styrene (SIS), or styrene‐ethylene/butylene‐styrene (SEBS) with clay were prepared by direct mixing of all components. Subsequently, they were compared with their grafted‐MAH copolymer counterparts. The asphalt blends were characterized with respect to their rheological, morphological, and physical properties. Experimental results revealed that SBS and SIS grafted‐copolymer composites increase the softening point by 1.5%–7%, while the penetration decreases by 2%–15% in comparison to the homologous nongrafted polymers. The improvement can be directly linked to the continuous network polymer in the asphalt blends. The combined use of styrene‐isoprene‐styrene‐g‐MAH (SIS‐g‐MAH) copolymer and clay impart higher elastic behavior than that of the other blends. G′ increases about 95% in comparison to that of SIS/Mt, while the complex viscosity is three decades larger in the low frequencies region. Elevated rutting resistance temperature (&gt;100°C), tanδ &lt;5, reveals a solid‐like behavior with no Newtonian plateau. SEBS‐g‐MAH/Mt presents diminished rheological properties with respect to those of SEBS/Mt due to poor dispersion and agglomeration of clay particles in the polymer and asphalt matrix.

Investigation on Some Algal Extracts as Appropriate Stabilizers for Radiation-Processed Polymers.

This study presents the appropriate solution, algal extracts, for the improvement of polymer durability when the material is subjected to acute oxidation damage. The investigated support, styrene-isoprene-styrene (SIS), is modified by three algal extracts: Chlorella vulgaris, Spirulina platensis, and Ascophyllum nodosum (Kelp) with a low concentration (1 wt%). The presence of polyhedral oligomeric silsesquioxane (POSS) ensures the growth of stability with respect to the pristine polymer. The thermal performances of the host polymer, indicated by chemiluminescence, reveal the essential contribution of an additive to the improvement in oxidation strength. The stability of the polymer adjusted by algal extracts is proved by the activation energy values, which increase from 49 kJ mol-1 to 89 kJ mol-1 for the same polymer modified with Ascophyllum nodosum. This main important characteristic is the consequence of the highly efficient activity of the polyphenol components of algal extracts and the effect of the three natural additives on the favorably changed kinetic parameters (oxidation induction time and onset oxidation temperature). The exposure of the polymer matrix to the damaging action of γ-rays does not affect the proper contributions to the fast delay in material ageing. The irradiation of 100 kGy, a usual technological dose, may be successfully applied in the radiation processing of a polymer stabilized with algal extracts due to the efficient protection of the additive as the chain-breaking agents.

Radiation Processing of Styrene-isoprene-styrene/Poly(ε-caprolactone) Blends.

The irradiation consequences on styrene-isoprene-styrene (SIS)/poly(ε-caprolactone) (PCL) blends are discussed starting from the oxidation initiation. Three characterization methods: chemiluminescence, differential scanning calorimetry and FTIR spectroscopy are applied. The differences that exist between the two components are revealed, when the oxidation rates of the inspected formulas depend on the blending proportion and the degradation conditions. The relevant activation energies characterizing the oxidation strength as well as the kinetic parameters of degradation during the accelerated damaging of blended polymers are related to the inhibition protection of PCL on the faster oxidation of SIS. The interaction between mixed components is revealed by the structural modifications simultaneously accompanied by the competition of formation and decay of radicals.

Development of material extrusion 3D printable ABS/PC polymer blends: influence of styrene–isoprene–styrene copolymer on printability and mechanical properties

ABSTRACT In this work, a series of 3D printable ABS/PC blends were successfully prepared via filament extrusion and fused deposition fabrication. Influence of styrene–isoprene–styrene (SIS) copolymer on printability and mechanical properties were examined. It was revealed that SIS not only enhances the compatibility of the two blend phases, but also enhances the 3D printability of the resulting materials. The effect of print temperature, bed temperature, print speed, layer thickness, number of shell and infill density on mechanical properties of the printed parts were investigated using the Taguchi experimental design method, and the samples were printed using optimized process parameters according to the Taguchi method. It was revealed that the optimization of extrusion multiplier was an efficient method to overcome voids in the printed parts. Interestingly, incorporation of SIS considerably improved the adhesion and distribution of the blend phases. In addition, with an increase in SIS content, tensile strength, yield strength, elastic modulus, and hardness were found to decrease, whereas Izod impact strength and percentage elongation values of the 3D-printable blend increased. Finally, an efficient post-processing technique was successfully employed to improve the aesthetics of additive manufactured specimens. This work provides a facile strategy to prepare new 3D-printable polymer blends with improved adhesion between phases and minimized voids in the printed parts.

Stability Study of the Irradiated Poly(lactic acid)/Styrene Isoprene Styrene Reinforced with Silica Nanoparticles.

In this paper, the stability improvement of poly(lactic acid) (PLA)/styrene-isoprene block copolymer (SIS) loaded with silica nanoparticles is characterized. The protection efficiency in the material of thermal stability is mainly studied by means of high accurate isothermal and nonisothermal chemiluminescence procedures. The oxidation induction times obtained in the isothermal CL determinations increase from 45 min to 312 min as the polymer is free of silica or the filler loading is about 10%, respectively. The nonisothermal measurements reveal the values of onset oxidation temperatures with about 15% when the concentration of SiO2 particles is enhanced from none to 10%. The curing assay and Charlesby–Pinner representation as well as the modifications that occurred in the FTIR carbonyl band at 1745 cm−1 are appropriate proofs for the delay of oxidation in hybrid samples. The improved efficiency of silica during the accelerated degradation of PLA/SIS 30/n-SiO2 composites is demonstrated by means of the increased values of activation energy in correlation with the augmentation of silica loading. While the pristine material is modified by the addition of 10% silica nanoparticles, the activation energy grows from 55 kJ mol−1 to 74 kJ mol−1 for nonirradiated samples and from 47 kJ mol−1 to 76 kJ mol−1 for γ-processed material at 25 kGy. The stabilizer features are associated with silica nanoparticles due to the protection of fragments generated by the scission of hydrocarbon structure of SIS, the minor component, whose degradation fragments are early converted into hydroperoxides rather than influencing depolymerization in the PLA phase. The reduction of the transmission values concerning the growing reinforcement is evidence of the capacity of SiO2 to minimize the changes in polymers subjected to high energy sterilization. The silica loading of 10 wt% may be considered a proper solution for attaining an extended lifespan under the accelerated degradation caused by the intense transfer of energy, such as radiation processing on the polymer hybrid.

A Comparative Study of Silver Microflakes in Digitally Printable Liquid Metal Embedded Elastomer Inks for Stretchable Electronics

AbstractPrinted soft conductive materials for stretchable electronics should have low electrical resistivity, high strain limit, and stable electrical properties when stretched. Previously, it has been shown that a bi‐phasic ink composed of silver (Ag) microflakes, eutectic gallium−indium (EGaIn) alloy, and styrene isoprene (SIS) block copolymer is a promising formulation for printed soft electronics and has the potential to satisfy the necessary criteria. In this study, further improvements to the ink formulation are explored, with a focus on how the choice of Ag microflakes affects the electrical and electromechanical properties of the composite. By using specific Ag microflakes, AgInGa‐SIS inks that have conductivity as high as 6.38 × 105 S m−1 and a strain limit of over 1000%, with low electromechanical coupling can be synthesized. More broadly, when comparing the composite with different silver flakes, there is a 176% relative difference in conductivity, &gt;600% difference in strain limit, and 277% relative difference in electromechanical coupling. To demonstrate the applicability of these inks for various use cases such as wearable bioelectronics, interconnects are printed for connecting electronic breakout boards with microcontrollers that provide a stable electrical connection when stretched, and the interconnects and electrodes of a wearable electrocardiography system that monitors the heart pulses in real‐time.

Performance evaluation of bitumen modified with styrene–isoprene-styrene and crumb rubber compound

Modifying bitumen with polymers has become inevitable to achieve resistance to severe traffic and environmental conditions. Researchers have focused on using modifiers with low-cost additives, such as crumb rubber (CR) obtained from waste vehicle tires, to enhance the efficiency of polymer modification. The present study investigated the effects of using styrene–isoprene-styrene (SIS) alone and in combination with CR on conventional and rheological properties of bitumen. To this end, viscosity, softening point, penetration, bending beam rheometer (BBR), and dynamic shear rheometer (DSR) tests were conducted. Elastic properties and performance grading were evaluated by the multi-stress creep recovery (MSCR) test. The use of 3% SIS with 7% CR gave one degree higher high-temperature performance level and 15% lower low-temperature stiffness than 6% SIS modification. It also provided 2.5 times lower non recoverable creep compliance and 1.5 times higher percent recovery than 6% SIS modification at 64 °C. The combined use of SIS and CR provided satisfactory performance under low- and high-temperature conditions and ensured a cost-effective solution when compared to the use of SIS polymer alone. Although SIS and CR modified binders exhibited satisfactory rutting resistance and elastic properties, the percent-difference criterion significantly restricted their high-temperature performance grade. According to this criterion, modification makes the binders suitable for extremely heavy traffic conditions without changing the resistance against temperature. Furthermore, it was determined that the estimated softening point, viscosity and rutting parameter values as a function of SIS and CR contents are highly compatible with the experimental results.

Silk inspired in-situ interlocked superelastic microfibers for permeable stretchable triboelectric nanogenerator

Wearables and on-skin triboelectric nanogenerator (TENG) highly desire intrinsic stretchability, favorable permeability and waterproofness, fibers/textiles as one of the ideal substrates could meet the requirements. However, realizing the versatile integration of hydrophobic elastic fibers with electrodes remains a huge challenge. Herein, inspired by the sericin-bundled silk with outstanding stretchability, we develop a microfibers-membrane with omnidirectional superelasticity, permeability and superhydrophobicity (SPSM) by synchronous electrospinning of styrene-isoprene (SIS) block copolymers and electrospraying of the fluorinated SiO2 nanoparticles. Co-solvent welding effect free of extra binders is proposed for the generation of in-situ anchored junctions between the SIS fibers, as well as achieving the anchoring effect for enhanced integration of SIS fiber-membranes with a variety of conductors such as sputtered gold (Au) layer, vacuum filtrated liquid metal-silver nanowires (LM-AgNWs) network and printed liquid metal-silver flakes-SIS (LM-AgFKs-SIS) ink, creating diverse elastic conductors and triboelectric-active-materials with optional advantages in mechanical stability, electrical robustness, triboelectric output and permeability. A self-cleaning SPSM-based single-electrode stretchable TENG (STENG) is demonstrated adaptive for tapping, stretching, bending and humidity, realizing a breathable self-powered sensor for materials identifying and hand posture monitoring. This work proposes a versatile superelastic fiber material competent for permeable STENGs and wearables with environment adaptivity.

Ultrahigh Sensitive Flexible Piezoresistive Sensor with Carbonized Metal–Organic Framework Fe3O4@MIL-100(Fe)

The piezoresistive sensor is an important device for sensing pressure and strain in flexible electronics. The application of composite conductive nanomaterials is helpful to obtain high-performance and multifunctional flexible piezoresistive sensors. Herein, using carbonized Fe3O4@MIL-100(Fe) as a composite conductive nanomaterial, an ultrahigh-sensitivity flexible piezoresistive sensor was achieved by a laser-processed template. Due to the porous Fe3O4@MIL-100(Fe) conductive nanomaterials and microridges on the styrene–isoprene–styrene substrate, the sensitivity of the sensor reaches 1727.46 kPa–1 in the pressure range of 0–50 Pa, which has a significant advantage over the reported sensors. Meanwhile, the sensor exhibits good cycling stability (>1500 cycles), a fast response of 24 ms, an instant recovery of 15 ms, excellent reversibility, and an antielectromagnetic interference capability. For practical applications, the sensor was applied for monitoring body physiological signals such as speech and artery pulses, indicating that the sensor is suitable for health monitoring. Moreover, using carbonized metal–organic frameworks with functional nanoparticles as conductive nanomaterials in the sensing unit provides a feasible way to develop multifunctional flexible piezoresistive sensors.