Die Müller‐Rochow‐Direktsynthese ist heute der bedeutendste Herstellungsprozess für die monomeren Ausgangsstoffe der Silikone (Polydimethylsiloxane), einer wirtschaftlich und technisch bedeutsamen ...Gruppe synthetischer Polymere. Wissenschaftlern gelang es nunmehr, Methylchlorid, das giftige und mutagene Edukt der Direktsynthese, durch ein umweltfreundliches und relativ ungefährliches Methylierungsmittel zu ersetzen.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Tactile sensors play a critical role in the Internet of Things (IoT) and wearable devices. However, although current tactile sensors can precisely measure pressure, the simple fabrication of ...stretchable high-performance tactile sensors with a broad measuring range and multifunctions is still challenging. Herein, an ink-direct writing 3D printing method is developed to fabricate novel stretchable dual-mode tactile sensors with coaxial fiber structure. The 3D printed coaxial fibers have an outer skin composed of silicone rubber and polytetrafluoroethylene micropowders thixotropic agent and an inner core of an ionic conductive solution composed of polyvinyl alcohol and sodium chloride. The coaxial fibers exhibit excellent electrical conductivity (0.54 S cm−1) and outstanding stretchability, as high as 390 %. The intersection of the two fibers constitutes a dual-mode tactile sensor which can operate in triboelectric or capacitive modes with complementary measurement ranges from 0.0003 to 0.4517 N. Besides, by combining the signals from the two modes, the sensor can identify the material that comes into contact with the sensor. A 3D printed network of tactile sensor arrays made of warp-weft interwoven coaxial fibers is able to accurately detect the locations of multi-point contact with the array. This dual-mode multifunctional tactile sensor can be widely used in various applications such as the IoT and wearable devices.
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•An ink-direct writing 3D printing method is developed to fabricate stretchable dual-mode tactile sensors..•The coaxial fibers showed high conductivity (0.54 S cm−1) and stretchability (390 %).•The tactile sensor can identify the material by combining the signals from the triboelectric and capacitive modes.•A 3D printed network of tactile sensor arrays is able to accurately detect the locations of multipoint contact.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
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•An extremely simple emulsion gel (EG) system is constructed by glutamic acid (Glu) and carefully engineered polysiloxanes (AESi).•The formation of EG did not need the addition of ...extra surfactants.•The stability of EG was provided by the in situ formed AESi/Glu supramolecular complex.
Emulsion gels (EGs), combined the advantages of both emulsions and gels, have attracted much attention in colloid chemistry. However, the preparation of EGs is usually complicated, which greatly hinders their development. Herein, we prepared a polydimethylsiloxane (PDMS) derivative which bears poly (ethoxylated ether) (PEO) segments at the ends and a few alkylamine groups on the side (denoted as AESi hereafter). When being mixed with an acidic amino acid (glutamic acid, Glu) in water, the amine groups of AESi were protonated, leading to an abrupt increase of its solubility. The AESi/Glu complex acts as a supramolecular amphiphile, which can form capsules in water. It can also stabilize excess AESi to form self-confined emulsions. In high loading of AESi, the emulsion droplets stack closely to form highly stable EGs. The EGs possess good viscoelasticity and are tunable by changing temperature or adding inorganic salts. By performing control experiments, structural features of the PDMS derivative and organic acid needed for the construction of EGs have been clarified. The strategy presented in this study provides new opportunity for the preparation and applications of EGs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A smart MXene-based textile was prepared by a facile dip-coating method.•The MXene-based textile was superhydrophobic and breathable.•The smart textile showed excellent photo-electro-thermal ...response.•The smart textile exhibited superb strain and temperature sensing performance.
Smart textile devices have now received increasing attention for potential application in wearable human motion monitoring, healthcare and personal thermal management. MXene (Ti3C2Tx), which is a new two-dimensional material with remarkable properties, has been widely applied in wearable electronics. However, it remains a challenge to prepare MXene based smart textile that possesses multifunctional wearable sensing applications and can also keep MXene from oxidizing. Here, we fabricated a waterproof and breathable smart textile by construction of a multiple core–shell structure, i.e., MXene decoration onto the polydopamine (PDA) modified elastic textile followed by polydimethylsiloxane (PDMS) coating. MXene wrapping the fibers formed the conductive network, while PDMS could not only protect the MXene from oxidation but also endow the textile with superhydrophobicity and thus corrosion resistance. The smart textile possessed outstanding and durable photo-thermal and electro-thermal conversion performance. More importantly, the textile electronic exhibited sensitive and stable strain sensing performance and temperature sensing capacity with a high thermal coefficient of resistance. Evidently, such smart textile device is highly promising for application in next generation all-in-one wearable electronics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Porous polymeric foams as dielectric layer for highly sensitive capacitive based pressure sensors have been extensively explored owing to their excellent flexibility and elasticity. Despite intensive ...efforts, most of previously reported porous polymer foams still suffer from difficulty in further lowering the attainable density limit of ≈0.1 g cm−3 while retaining high sensitivity and compressibility due to the limitations on existing fabrication techniques and materials. Herein, utilizing 3D interconnected networks of few‐layer hexagonal boron nitride foams (h‐BNFs) as supporting frameworks, lightweight and highly porous BN/polydimethylsiloxane composite foams (BNF@PDMS) with densities reaching as low as 15 mg cm−3 and permittivity close to that of air are fabricated. This is the lightest PDMS‐based foam reported to date. Owing to the synergistic effects between BN and PDMS, these lightweight composite foams possess excellent mechanical resilience, extremely high compressibility (up to 95% strain), good cyclic performance, and superelasticity. Being electrically nonconductive, the potential application of BNF@PDMS as a dielectric layer for capacitive sensors is further demonstrated. Remarkably, the as‐fabricated device can perform multiple sensing functions such as noncontact touch sensor, environmental monitoring sensor, and high sensitivity pressure sensor that can detect extremely low pressures of below 1 Pa.
Boron nitride (BN) foams are used as frameworks to produce the lightest polydimethylsiloxane (PDMS)‐based foams to date with densities reaching as low as 15 mg cm−3. The BN/PDMS composite foams (BNF@PDMS) display excellent mechanical resilience, extremely high compressibility, and superelastic properties. Owing to these unique properties, the BNF@PMDS shows great potential as a dielectric layer for multifunctional capacitive sensor applications.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•A PDMS elastomer based on imine groups is successfully prepared using Schiff base reaction.•The elastomer features an outstanding optical transmittance more than 80% in visible ...region.•The elastomer exhibits good mechanical strength, stretchability, and excellent self-healing properties.•The elastomer is recyclable and can be used as adhesives.
Smart materials with self-healing properties that can heal themselves with restored mechanical performance are highly desired. Herein, a transparent healable PDMS (HPDMS) elastomer based on imine bonds is successfully prepared from amino-modified polydimethylsiloxane (PDMS) and 1,4-diformylbenzene (DFB) through a simple method. The concentration of DFB has a great effect on the gelation process. The elastomer features an outstanding optical transmittance (more than 80%) over the full visible light region. The results of TGA and DSC indicate that the HPDMS elastomer is highly flexible at room temperature and can be used in a wide temperature range. The presence of imine bonding and the formation of Schiff base linkages is proved by the FT-IR and Raman spectra. The reversible imine bond can promote the contact of the fracture surfaces and result in quick and repeatable self-healing without any external intervention such as heat or light. Furthermore, the elastomer exhibits excellent recyclability and reprocessability. Besides, the adhesion test reveals the potential of the elastomer in application as adhesives. We anticipate that this strategy can be employed to prepare a transparent PDMS elastomer with mechanical strength, stretchable, and excellent self-healing properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pulling carbon dioxide out of the airA challenge in the design of polymeric membranes for gas separation is the tradeoff between permeability, or how fast gases can flow through the membrane, and ...selectivity, the ability to separate one gas from another. In general, the more selective the membrane, the more slowly gases can flow through it. Sandru et al. overcame this tradeoff through a layered design. They used a bottom layer of porous polyacrylonitrile that acts as a physical support for the middle layer of either elastomer-like polydimethylsiloxane or glassy-type polytetrafluoroethylene. The authors then grafted a patchy layer of polyvinylamine, which selectively attracts carbon dioxide, thus pulling it into the membrane and leading to much higher separation from nitrogen. —MSL
•Polydimethylsiloxane (PDMS) surface treatment was carried out using C4F8/O2/Ar plasma.•The Surface energy control of PDMS for direct transfer of graphene to various thin films.•Mechanism behind the ...changes in the surface energy of PDMS was investigated using plasma diagnosis, surface energy analysis, and XPS.
We conducted plasma treatment on polydimethylsiloxane (PDMS) films using inductively coupled C4F8/O2/Ar gas mixture plasma to modify their surface properties. We investigated the relationship between plasma characteristics and the changes in PDMS surfaces in order to understand the surface modification mechanism. The surface characteristics of PDMS films were evaluated in detail by surface energy measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Using contact angle measurements, it was confirmed that the surface, polar, and dispersive energies of the plasma-treated PDMS films increased as the O2 gas ratio increased. AFM analysis showed that the roughness of plasma-treated PDMS surfaces increased when the O2 gas ratio increased. XPS analysis confirmed the presence of a functional group CFx (X=1, 2, and 3) in C4F8-rich plasma and a functional group OH in O2-rich plasma. It was confirmed that the surface energy of the PDMS films could be controlled by controlling the C4F8/O2/Ar plasma treatment parameters which should be required for applying the direct transfer technique in each material having different surface energy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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