Entropy‐Driven Self‐Healing of Metal Oxides Assisted by Polymer–Inorganic Hybrid Materials

Abstract

robustness to mechanical stress. The combination of these two properties is typically found in inorganic materials such as metals and metal oxides, therefore inorganic materials which are able to selfrecover are in high demand. [3] Examples of self-healing materials for applications in electronics and related fields are scarce. The few existing ones describe materials that can restore their crack-degraded conductivity, [4] including semiconducting polymers, [5] conductive polymer networks, [6,7] microchannels, and microcapsules filled with Ga-based liquid metal alloys, [8,9] or metal-containing solutions, [10] and ionic hydrogels. [11,12] Further progress remains challenging, primarily because of the lack of feasible healing agents and suitable ways to supply them to the damaged site. In theory, the most logical way to construct self-healing materials is by the entrapment of reactive precursors within the bulk material which reacts only upon exposure to air, for example at a damaged site. Unfortunately, this is a complex and potentially dangerous approach due to the reactivity of the applied chemicals. [10] We aim to widen the pool of self-healing materials from soft matter toward metal oxides (MeOs), including the highly demanded transparent conductive oxides (TCOs). MeOs are typically very inert in ambient conditions. Healing cracks in MeOs by recrystallization would require considerable energy investment. If a device contains polymers, for example as a substrate in the case of flexible electronics, such an energy input will be incompatible with the thermal range of the polymers and is therefore not applicable. Self-healing of inorganic materials and structures could alternatively be realized by loading a polymeric substrate with inorganic nanoparticles (NPs) and enabling their mobility inside the substrate. The spatial distribution of NPs can be tuned by harnessing both enthalpy and entropy. [13][14][15][16] In suitable material systems, the NPs can migrate to new damage-induced interfaces, agglomerating and thereby performing self-healing events. [17] However, a polymer coating on inorganic NPs was required in that work, which shielded the NPs and therefore affected their functional properties. [17] An entropy-driven NP reorganization, as described in this work, suggests a promising and safe alternative pathway to allow the healing of metal oxides. As a first step, a system with MeO nanoparticles, well-dispersed inside a preferably polymeric host matrix, is needed. This can be obtained by vapor phase infiltration (VPI) of a polymer with inorganic materials. [18][19][20] The approach will yield a hybrid or nanocomposite polymerinorganic material with an inorganic thin film coating of the same or another MeO, depending on the process setup. [21] This Enabling self-healing of materials is crucially important for saving resources and energy in numerous emerging applications. While strategies for the selfhealing of polymers are advanced, mechanisms for semiconducting inorganic materials are scarce due to the lack ...

High‐Entropy Enhanced Microwave Attenuation in Titanate Perovskites

“…Due to their unique properties, high‐entropy ceramics have been widely used in the fields of Li‐ion batteries, electrochemical energy storage, and capacitive energy storage. [ 6b,9c,11 ] Recently, high‐entropy ceramics have also been used in the field of electromagnetic (EM) wave absorption. [ 12 ] High‐performance microwave‐absorbing materials have attracted great interest in civilian fields, owing to the intensification of EM wave pollution with the increasing popularity of electronic equipment, particularly in the gigahertz (GHz) band range.…”

Introducing a Robust Flexible Conductive Hybrid: Indium Oxide-ParyleneC Obtained by Vapor Phase Infiltration

“…Given the strong oxidative character of H 2 O 2 , coupled with its small size, the generation of carbonyl functions inside the bulk of ParyleneC may be the primary reason for the observed differences in infiltration depth and indium oxide load inside the polymer. In contrast, the application of H 2 O will only allow physical trapping and mobility of the metal oxide particles inside the polymer, which, driven by entropy, 16 are likely to migrate to the polymer's surface rather than staying in the bulk. Processing temperatures affect the infiltration in different ways.…”

“…In the case of indium oxide infiltrated into ParyleneC, the hybrid was recently shown to result in the evolution of self-healing properties. 16 Namely, ruptures and defects in thin indium and zinc oxide films, coated on surfaces of ParyleneC, were mended with the corresponding metal oxides that previously infiltrated into the bulk of the polymer. This phenomenon was explained with the redistribution of the infiltrated metal oxide clusters toward the new interfaces formed upon defect generation.…”

“…Along with deepening the understanding of the physics and chemistry behind VPI, a variety of hybrid systems were developed. The infiltrated inorganic compound of the fabricated hybrid systems is typically a metal oxide such as Al 2 O 3 , TiO 2 , ZnO, , SnO 2 , WO x , VO x , Ga 2 O 3 , or In 2 O 3 . , The latter mentioned In 2 O 3 is of paramount importance for the electronics industry, as it is the key component in materials used for transparent electrode applications, especially in indium tin oxide (ITO) or indium zinc oxide (IZO) . It has, therefore, been applied in a number of optoelectronics applications, for example, as transparent conductive oxide (TCOs) in flat panel and touch screen displays and in thin-film transistors, solar panels smart windows, or biosensors .…”

Modular Engineering of a DNA Tetrahedron-Based Nanomachine for Ultrasensitive Detection of Intracellular Bioactive Small Molecules

“…The design of the nanomachine is based on the following considerations: the aptamer module was used based on the fact that specific aptamers can bind to molecular targets with high affinity and excellent specificity, depending on their unique nucleotide sequence. − In the presence of ATP, the aptamer module can release the initiator to activate the next module. Next, with the aid of the entropy-driven module, the released initiator can be recycled and amplified through an enzyme-free toehold-mediated strand displacement system to significantly enhance the detection speed and sensitivity. , Notably, as a signal amplification strategy, the entropy-driven module is powered thermodynamically by entropic gain, with the base numbers remaining unchanged. , Thus, in contrast to other enzyme-free amplification methods, the entropy-driven module effectively circumvents circuit leakage and exhibits a higher signal-to-noise ratio, thus making the process less noisy and more reliable. , Finally, a DNA tetrahedron vehicle was used as the transportation module because DNA-based delivery devices have been widely utilized in in vivo applications, including the in situ detection of various biomarkers, , drug delivery, and biomedical treatment. − Among its favorable attributes, it is well established that a DNA-based carrier vehicle features biosafety, biocompatibility, and the ability to cross the cell membrane without the need for transfection agents. , …”