Mechanical failure of π‐conjugated polymer thin films is unavoidable under cyclic loading conditions, due to intrinsic defects and poor resistance to crack propagation. Here, the first tear‐resistant ...and room‐temperature self‐healable semiconducting composite is presented, consisting of conjugated polymers and butyl rubber elastomers. This new composite displays both a record‐low elastic modulus (<1 MPa) and ultrahigh deformability with fracture strain above 800%. More importantly, failure behavior is not sensitive to precut notches under deformation. Autonomous self‐healing at room temperature, both mechanical and electronic, is demonstrated through the physical contact of two separate films. The composite film also shows device stability in the ambient environment over 5 months due to much‐improved barrier property to both oxygen and water. Butyl rubber is broadly applicable to various p‐type and n‐type semiconducting polymers for fabricating self‐healable electronics to provide new resilient electronics that mimic the tear resistance and healable property of human skin.
A mechanically durable and electronically stable semiconducting composite is engineered by introducing a blend of donor–acceptor polymer and butyl rubber elastomer. The composite exhibits ultralow modulus, ultrahigh deformability, tear resistance, and self‐healing performance, as well as ambient stable device stability. This method is widely applicable to different semiconducting polymers.
Donor–acceptor (D–A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous ...structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)‐based D–A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side‐chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear‐chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side‐chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field‐effect transistors. This study deconvolutes the alignment of different components within the thin‐film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers.
In this study, the chain alignment mechanism of semiconducting polymers under tensile deformation is carefully investigated. The thin‐film mechanical behavior is determined by the film‐on‐water tensile tester, while multimodal characterization methods are applied to capture the microstructural evolution, including hard, tender, soft X‐ray, UV–vis, and molecular simulation. Both crystallite rotation and chain sliding are determined to be the primary mechanisms during deformation.
Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a ...universal activity descriptor for both hydrogen‐evolution reaction (HER) and oxygen‐evolution reaction (OER) is not yet developed. Moreover, a unifying concept is not yet established to simultaneously understand HER/OER mechanisms. Here, the relationships between HER/OER activities in three common electrolytes and over ten representative material properties on 12 3d‐metal‐based model oxides are rationally bridged through statistical methodologies. The orbital charge‐transfer energy (Δ) can serve as an ideal universal descriptor, where a neither too large nor too small Δ (≈1 eV) with optimal electron‐cloud density around Fermi level affords the best activities, fulfilling Sabatier's principle. Systematic experiments and computations unravel that pristine oxide with Δ ≈ 1 eV possesses metal‐like high‐valence configurations and active lattice‐oxygen sites to help adsorb key protons in HER and induce lattice‐oxygen participation in the OER, respectively. After reactions, partially generated metals in the HER and high‐valence hydroxides in the OER dominate proton adsorption and couple with pristine lattice‐oxygen activation, respectively. These can be successfully rationalized by the unifying orbital charge‐transfer theory. This work provides the foundation of rational material design and mechanism understanding for many potential applications.
A universal activity descriptor (orbital charge‐transfer energy) is successfully extracted from various materials’ physicochemical properties for both hydrogen‐evolving and oxygen‐evolving reactions in multiple electrolytes. Systematic experiments and computations reveal the life‐cycle HER and OER mechanisms and identify the unifying orbital charge‐transfer theory as a powerful mechanism analysis tool and foundation.
Heterocyclic trifluoromethylation is efficiently initiated through a photochemical reaction utilizing an electron donor–acceptor (EDA) complex, proceeding smoothly without the use of photocatalysts, ...transition‐metal catalysts, or additional oxidants. This method has been optimized through extensive experimentation, demonstrating its versatility and efficacy across various substrates, including quinoxalinones, coumarins, and indolones. Notably, this approach enables the practical synthesis of trifluoromethylated quinoxalinones on a gram scale. Mechanistic investigations that incorporate radical trapping and ultraviolet/visible spectroscopy, confirmed the formation of the an EDA complex and elucidated the reaction pathways. This study highlights the crucial role of EDA photoactivation in trifluoromethylation, significantly expanding the application scope of EDA complexes in chemical synthesis.
This study presents a novel Electron Donor‐Acceptor Complex (EDA) complex‐based method for trifluoromethylating heterocycles, bypassing traditional photocatalysts and oxidants. Utilizing 395 nm light, it efficiently produces trifluoromethylated quinoxalinones, coumarins, and indolones. The research emphasizes EDA photoactivation‘s crucial role, thoroughly documented through experimental, mechanistic, and spectroscopic analyses, thereby expanding EDA complexes′ utility in chemical synthesis.
Copper is king! A convenient method for the synthesis of trifluoromethylated heteroaromatic compounds under mild conditions has been developed based on the observation that 1 can be reduced by ...certain metals (see scheme). Substrate 1 is assumed to be reduced by copper via a single‐electron transfer mechanism, and CuCF3 is the most probable intermediate in this reaction. DMF=N,N‐dimethylformamide, Tf=triflate.
A self-healing dielectric elastomer is achieved by the incorporation of metal–ligand coordination as cross-linking sites in nonpolar polydimethylsiloxane (PDMS) polymers. The ligand is ...2,2′-bipyridine-5,5′-dicarboxylic amide, while the metal salts investigated here are Fe2+ and Zn2+ with various counteranions. The kinetically labile coordination between Zn2+ and bipyridine endows the polymer fast self-healing ability at ambient condition. When integrated into organic field-effect transistors (OFETs) as gate dielectrics, transistors with FeCl2 and ZnCl2 salts cross-linked PDMS exhibited increased dielectric constants compared to PDMS and demonstrated hysteresis-free transfer characteristics, owing to the low ion conductivity in PDMS and the strong columbic interaction between metal cations and the small Cl– anions which can prevent mobile anions drifting under gate bias. Fully stretchable transistors with FeCl2-PDMS dielectrics were fabricated and exhibited ideal transfer characteristics. The gate leakage current remained low even after 1000 cycles at 100% strain. The mechanical robustness and stable electrical performance proved its suitability for applications in stretchable electronics. On the other hand, transistors with gate dielectrics containing large-sized anions (BF4 –, ClO4 –, CF3SO3 –) displayed prominent hysteresis due to mobile anions drifting under gate bias voltage. This work provides insights on future design of self-healing stretchable dielectric materials based on metal–ligand cross-linked polymers.
Difluoromethylation is of prime importance for its applicability in functionalizing diverse fluorine‐containing heterocycles, which are core groups in diverse biologically and pharmacologically ...active ingredients. Herein, we report a novel transition metal‐ and oxidant‐free visible light‐photoinduced protocol for direct C(sp2)‐H difluoromethylation of heterocycles. The reaction afforded difluoromethyl heterocycles without using colored organic dyes and metal catalysts in good yields and showed a broad substrate tolerance. Moreover, the representative products exhibited potential drug activity, and one product showed good antifungal activities against Rhizoctorzia solani (62.7 %).
A highly efficient, transition metal‐ and oxidant‐free, direct C(sp2)‐H difluoromethylation of heterocycles through visible light‐induced electron transfer was developed. The reaction afforded difluoromethyl heterocycles by only using photoexcited diacetyl. The reaction showed a broad substrate tolerance and gave the products in good yields. Moreover, the representative products exhibited potential drug activity and showed good antifungal activities.
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