With growing sustainability concerns, the need for products that facilitate easy disassembly and reuse has increased. Adhesives, initially designed for bonding, now face demands for selective ...removal, enabling rapid assembly‐disassembly and efficient maintenance across industries. This need is particularly evident in the display industry, with the rise of foldable devices necessitating specialized adhesives. A novel optically clear adhesive (OCA) is presented for foldable display, featuring a unique UV‐stimulated selective removal feature. This approach incorporates benzophenone derivatives into the polymer network, facilitating rapid debonding under UV irradiation. A key feature of this method is the adept use of visible‐light‐driven radical polymerization for OCA film fabrication. This method shows remarkable compatibility with various monomers and exhibits orthogonal reactivity to benzophenone, rendering it ideal for large‐scale production. The resultant OCA not only has high transparency and balanced elasticity, along with excellent resistance to repeated folding, but it also exhibits significantly reduced adhesion when exposed to UV irradiation. By merging this customized formulation with strategically integrated UV‐responsive elements, an effective solution is offered that enhances manufacturing efficiency and product reliability in the rapidly evolving field of sustainable electronics and displays. This research additionally contributes to eco‐friendly device fabrication, aligning with emerging technology demands.
A UV‐removable optically clear adhesive (OCA) is introduced, ideal for the sustainability‐focused electronics industry, particularly for foldable devices requiring easy disassembly and robust, eco‐friendly materials.
Abstract
Current technological advances in the organic light‐emitting diode panel design of foldable smartphones demand advanced adhesives with UV‐blocking abilities, beyond their conventional roles ...of bonding objects and relieving deformation stress. However, optically clear adhesives (OCAs) with UV‐blocking ability cannot be prepared using conventional UV‐curing methods relying on a photoinitiator. Herein, a new acrylic resin that can be efficiently cured using visible light without oxygen removal is presented, which may be used to develop UV‐blocking OCAs for use in current flexible displays. A novel photocatalyst and a specific combination of additives facilitate sufficiently rapid curing under visible light in the presence of UV‐absorbers. Only a very small amount of the highly active photocatalyst is required to prepare UV‐blocking OCA films with very high transparency in the visible region. Using this system, a UV‐blocking OCA that nearly meets the specifications of an OCA used in commercialized foldable smartphones is realized. This technology can also be utilized in other applications that require highly efficient visible light curing, such as optically clear resins, dental resins, and 3D/4D‐printable materials.
Magnetic nanofibrous scaffolds of poly(caprolactone) (PCL) incorporating magnetic nanoparticles (MNP) were produced, and their effects on physico-chemical, mechanical and biological properties were ...extensively addressed to find efficacy for bone regeneration purpose. MNPs 12 nm in diameter were citrated and evenly distributed in PCL solutions up to 20% and then were electrospun into nonwoven nanofibrous webs. Incorporation of MNPs greatly improved the hydrophilicity of the nanofibers. Tensile mechanical properties of the nanofibers (tensile strength, yield strength, elastic modulus and elongation) were significantly enhanced with the addition of MNPs up to 15%. In particular, the tensile strength increase was as high as ∼25 MPa at 15% MNPs vs. ∼10 MPa in pure PCL. PCL-MNP nanofibers exhibited magnetic behaviors, with a high saturation point and hysteresis loop area, which increased gradually with MNP content. The incorporation of MNPs substantially increased the degradation of the nanofibers, with a weight loss of ∼20% in pure PCL, ∼45% in 10% MNPs and ∼60% in 20% MNPs. Apatite forming ability of the nanofibers tested in vitro in simulated body fluid confirmed the substantial improvement gained by the addition of MNPs. Osteoblastic cells favored the MNPs-incorporated nanofibers with significantly improved initial cell adhesion and subsequent penetration through the nanofibers, compared to pure PCL. Alkaline phosphatase activity and expression of genes associated with bone (collagen I, osteopontin and bone sialoprotein) were significantly up-regulated in cells cultured on PCL-MNP nanofibers than those on pure PCL. PCL-MNP nanofibers subcutaneously implanted in rats exhibited minimal adverse tissue reactions, while inducing substantial neoblood vessel formation, which however, greatly limited in pure PCL. In vivo study in radial segmental defects also signified the bone regeneration ability of the PCL-MNP nanofibrous scaffolds. The magnetic, bone-bioactive, mechanical, cellular and tissue attributes of MNP-incorporated PCL nanofibers make them promising candidate scaffolds for bone regeneration.
Efficient current‐induced switching of perpendicular magnetization is an essential task in spintronics for realizing high‐performance information processing and for storage device application. ...However, the spin‐orbit torque (SOT) by injection of in‐plane polarized spins cannot deterministically switch the magnetization of ferromagnetic thin films with perpendicular magnetic anisotropy (PMA) without an additionally applied in‐plane external magnetic field to break the symmetry of the PMA. Considering the difficulties of applying the magnetic field to the localized area only within a device structure, it is essential to contrive a facile field‐free SOT switching mechanism. Here, deterministic field‐free SOT switching of perpendicular magnetization is achieved in amorphous and ferrimagnetic Gd/Co multilayers accompanied by a tilted magnetic anisotropy axis. This tilted anisotropy originates from the combined contributions of many internal anisotropies in different orientations from the multilayers and is shown to be controllable. It is expected that the introduction of controlled tilted anisotropy into Gd/Co multilayers over the entire film surface in the present study can be extended to the development of wafer‐scale technologies for the spintronics memory and logic devices.
The slightly tilted magnetic anisotropy axis of the perpendicular magnetic anisotropy film enables the field‐free magnetization switching of magnetization by spin currents. Stable switching operations can be repeatedly executed using pulsed spin currents.
Epidermal Electronics Kim, Dae-Hyeong; Lu, Nanshu; Ma, Rui ...
Science (American Association for the Advancement of Science),
08/2011, Volume:
333, Issue:
6044
Journal Article
Peer reviewed
Open access
We report classes of electronic systems that achieve thicknesses, effective elastic moduli, bending stiffnesses, and areal mass densities matched to the epidermis. Unlike traditional wafer-based ...technologies, laminating such devices onto the skin leads to conformal contact and adequate adhesion based on van der Waals interactions alone, in a manner that is mechanically invisible to the user. We describe systems incorporating electrophysiological, temperature, and strain sensors, as well as transistors, light-emitting diodes, photodetectors, radio frequency inductors, capacitors, oscillators, and rectifying diodes. Solar cells and wireless coils provide options for power supply. We used this type of technology to measure electrical activity produced by the heart, brain, and skeletal muscles and show that the resulting data contain sufficient information for an unusual type of computer game controller.
The magnetic skyrmion is a topologically protected spin texture that has attracted much attention as a promising information carrier because of its distinct features of suitability for high‐density ...storage, low power consumption, and stability. One of the skyrmion devices proposed so far is the skyrmion racetrack memory, which is the skyrmion version of the domain‐wall racetrack memory. For application in devices, skyrmion racetrack memory requires electrical generation, deletion, and displacement of isolated skyrmions. Despite the progress in experimental demonstrations of skyrmion generation, deletion, and displacement, these three operations have yet to be realized in one device. Here, a route for generating and deleting isolated skyrmion‐bubbles through vertical current injection with an explanation of its microscopic origin is presented. By combining the proposed skyrmion‐bubble generation/deletion method with the spin–orbit‐torque‐driven skyrmion shift, a proof‐of‐concept experimental demonstration of the skyrmion racetrack memory operation in a three‐terminal device structure is provided.
A new route to generate and delete magnetic skyrmion‐bubbles electrically is presented using a vertical current path. The vertical current path concept is easy to integrate with a widely used spin–orbit torque device. Using the vertical current path with a spin–orbit‐torque device, core operations for a skyrmion racetrack memory device in a three‐terminal device are demonstrated.
Complete reconstruction of damaged periodontal pockets, particularly regeneration of periodontal ligament (PDL) has been a significant challenge in dentistry. Tissue engineering approach utilizing ...PDL stem cells and scaffolding matrices offers great opportunity to this, and applying physical and mechanical cues mimicking native tissue conditions are of special importance. Here we approach to regenerate periodontal tissues by engineering PDL cells supported on a nanofibrous scaffold under a mechanical-stressed condition. PDL stem cells isolated from rats were seeded on an electrospun polycaprolactone/gelatin directionally-oriented nanofiber membrane and dynamic mechanical stress was applied to the cell/nanofiber construct, providing nanotopological and mechanical combined cues. Cells recognized the nanofiber orientation, aligning in parallel, and the mechanical stress increased the cell alignment. Importantly, the cells cultured on the oriented nanofiber combined with the mechanical stress produced significantly stimulated PDL specific markers, including periostin and tenascin with simultaneous down-regulation of osteogenesis, demonstrating the roles of topological and mechanical cues in altering phenotypic change in PDL cells. Tissue compatibility of the tissue-engineered constructs was confirmed in rat subcutaneous sites. Furthermore, in vivo regeneration of PDL and alveolar bone tissues was examined under the rat premaxillary periodontal defect models. The cell/nanofiber constructs engineered under mechanical stress showed sound integration into tissue defects and the regenerated bone volume and area were significantly improved. This study provides an effective tissue engineering approach for periodontal regeneration-culturing PDL stem cells with combinatory cues of oriented nanotopology and dynamic mechanical stretch.
Vitrimer epoxy, capable of stress‐relaxation, has gathered attention for its ability to counter the brittleness and rigidity of thermosets. However, to date, only two strategies are proposed to ...address the high enthalpic barrier of a dynamic exchange reaction using high dosages of external catalysts or niche moieties as internal catalysts. Herein, solvate ionic liquids (SILs) are incorporated into commercial epoxy‐based vinylogous urethane (VU) vitrimers. During curing, the SILs facilitate epoxy ring‐opening and amine‐addition reactions, significantly reducing gel times. Furthermore, after network formation, the SILs accelerate transamination reaction within the VU networks at a dosage of only 0.5–2 mol%. This can be attributed to their high miscibilities and Lewis acidic characters, which significantly reduce the activation energy of transamination (24 kJ mol−1) in the SIL‐incorporated vitrimer. Thus, a high‐performing vitrimer epoxy is prepared, featuring a glassy modulus (>109 Pa) at room temperature and an extremely short stress‐relaxation time (≈19 s) at 160 °C. Moreover, a soft encapsulation approach is demonstrated using the vitrimer epoxy, proving the possibility of a simultaneous deformable (bent) encapsulation, reduced warpage of a flexible printed circuit board, and selective removal of encapsulants.
Solvate ionic liquids accelerated dynamic exchange reactions in a commercial epoxy‐based vitrimer. Owing to their excellent solubility and catalytic activity, only 2 mol% dosage is sufficient to realize the supreme stress‐relaxation capability (τ* ≈19 s) of the resultant vitrimer, without compromising mechanical strengths. The vitrimer as an encapsulant is utilized for flexible hybrid electronics, achieving warpage‐reduction, reworkability, and multiple‐bendability.
Hydrothermal carbonization (HTC) is an active area of research in synthesizing carbon-rich materials because of its ability to transform wet biomass into valuable products. Carbon-rich materials have ...received a great deal of attention because carbon is a raw material for several industrial products and their production from various biomasses is currently an active area of research. In addition, lignocellulosic biomass has been of great interest as precursors for the preparation of carbon-rich materials because of their low cost and due to environmental concerns. This review exhibits the research on the hydrothermal carbonization of lignocellulosic biomass, production of carbon-rich materials or carbon spheres or hydrochar by the HTC process and the role of water and the proposed mechanism in the HTC process. This research on hydrothermal carbonization mostly focused on lignocellulosic biomass materials and the effect of process parameters including the temperature, pressure residence time, pH, heating rate and substrate concentration are also discussed. The reaction mechanisms of hydrolysis, dehydration or decarboxylation and carbonization are elaborated in detail. Solid carbon-rich materials have a wide range of applications as environmental additives, biofuels, catalysts and energy storage and have been covered in detail. At the end of the review, we deliver an outlook on future research prospects and applications of hydrothermal carbon-rich materials.
The key to producing high‐energy Li‐ion cells is ensuring the interfacial stability of Si‐containing anodes and Ni‐rich cathodes. Herein, 4‐(allyloxy)phenyl fluorosulfate (APFS), a multi‐functional ...electrolyte additive that forms a mechanical strain‐adaptive solid electrolyte interphase (SEI) comprising LiF and polymeric species, and a thermally stable cathode–electrolyte interface containing SO and SF species. The radical copolymerization of vinylene carbonate (VC) with APFS via electrochemical initiation creates a spatially deformable polymeric SEI on the SiG‐C (30 wt.% graphite + 70 wt.% SiC composite) anode, with large volume changes during cycling. Moreover, the APFS‐promoted interfacial layers reduce Ni dissolution and deposition. Furthermore, APFS deactivates the Lewis acid PF5, thereby inhibiting hydrolyses that produce unwanted HF. These results indicate that the combined use of VC with APFS allows capacity retentions of 72.5% with a high capacity of 143.5 mAh g−1 in SiG‐C/LiNi0.8Co0.1Mn0.1O2 full cells after 300 cycles at 45 °C.
The combination of 4‐(allyloxy)phenyl fluorosulfate (APFS) and vinylene carbonate enables facile generation of a thermally stable cathode‐electrolyte interface on NCM811 cathodes and an elastic solid electrolyte interphase on SiG‐C anodes, enabling superior performance of Li‐ion cells. Further, APFS deactivated the Lewis acid PF5, the potential source of corrosive HF, leading to an enhancement in electrolyte stability.
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