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Extended Oxygen Octahedral Tilt Proximity near Oxide Heterostructures
No full textThe oxide interfaces between materials with different structural symmetries have been actively studied due to their novel physical properties. However, the investigation of intriguing interfacial phenomena caused by the oxygen octahedral tilt (OOT) proximity effect has not been fully exploited, as there is still no clear understanding of what determines the proximity length and what the underlying control mechanism is. Here, we achieved scalability of the OOT proximity effect in SrRuO3 (SRO) by epitaxial strain near the SRO/SrTiO3 heterointerface. We demonstrated that the OOT proximity length scale of SRO is extended from 4 unit cells to 14 unit cells by employing advanced scanning transmission electron microscopy. We also suggest that this variation may originate from changes in phonon dispersions due to electron-phonon coupling in SRO. This study will provide in-depth insights into the structural gradients of correlated systems and facilitate potential device applications
Dual crosslinking polymer networks: Correlation between polymer topologies and self-healing efficiency
No full textThe topologies of polymers can impact the performance of polymeric materials, including their chemical and physical properties. In this work, a dynamic covalent bond of boronate ester was introduced by the addition of 4-vinylphenylboronic acid to the rich hydroxyl groups of polyglycidols (PGs) with different topologies, including branched cyclic, hyperbranched, and linear PGs. The formation of the dual crosslinked polymer networks, which consisted of dynamic covalent bonds (B???O) and static covalent bonds, was confirmed by thermogravimetric analysis and a swelling test. In addition, the mechanical properties of the cured materials were evaluated using a rheometer, dynamic mechanical analysis, and nanoindentation. Scratch tests and tensile tests were used to determine the self-healing effectiveness of polymer topologies. Intriguingly, based on the polymer topologies, the crosslinked network with a branched cyclic structure (bc-cPGB) exhibited a greater self-healing efficiency and modulus than hyperbranched networks (hb-cPGB). These findings indicate that the physical properties of polymer networks are influenced by the network mesh space and preferred intermolecular crosslinking of the branched cyclic structure. In addition, to maximize the benefits of the dual crosslinking system, the dynamic B???O bonds were utilized for recycling cured materials, and the PG prepolymer was successfully recovered from cPGB by adding pinacol to THF with a yield of 99.5%. These findings demonstrate the significance of topology control in highly adaptable advanced functional materials
Topological Characteristics of Entangled Short-Chain Branched Polymers in Comparison to the Linear Analogs under Shear Flow
No full textEfficient Generation of Reactive Oxygen Species and Their Protein Dysfunction Mechanism for Photodynamic Therapy
No full textA study on miscibility properties of polyacrylonitrile blending films with biodegradable polymer, shellac
No full textPolyacrylonitrile (PAN) films blended with shellac, biodegradable polymer, were prepared via simple solution casting method. The miscibility of PAN with shellac polymer was investigated and the optimal concentration of shellac in terms of hydrogen bonding between shellac and PAN chain was determined to be used as a novel biomass carbon precursor. Shellac and PAN chain could exert interaction and the interaction facilitates to loose the crystalline structure of the PAN chain, suggesting that the decrease of the oxidation temperature of the PAN chain in the PAN/shellac blends film by the introduction of shellac segments. The optimal PAN/shellac blends film exhibited outstanding mechanical performances (73.8% higher tensile strength, 60% higher storage modulus compared with control PAN film) showing homogeneous blending state
Toward Sustaining Bioplastics: Add a Pinch of Seasoning
No full textModern society can no longer sustain accumulating plastic pollution without intervention; plastic waste has even found its way into the food that we consume. Unfortunately, biodegradable alternatives lack sound commercial and economic distinctiveness because mechanical strength and biodegradability are typically mutually exclusive. Inspired by fine cuisine, we introduce a novel synthetic method, referred to as "seasoning", which consists of adding a minimal amount of a biobased multifunctional monomer to pinch the amorphous domains of poly(butylene succinate). Seasoning with only 0.03 mol % of a biobased monomer led to a significantly improved oxygen barrier, high strength (86 MPa), and excellent elongation at break (654%). To the best of our knowledge, this "seasoning" approach with the significant property improvement provided is unique in the bioplastics research field. The proposed approach is highly scalable, relies on existing industrial production, and has the potential to expand current biodegradable plastic applications through its simplicity
High temperature phases of borophene: borophene glass and liquid
No full textBorophene is a family of two-dimensional (2D) boron materials containing many isomers with different hole concentrations and distributions in a triangular lattice. Although it has been widely studied theoretically and some have been synthesized experimentally, their thermodynamic properties are still unexplored. Based on density functional theory (DFT), we developed an accurate potential for the kinetic Monte Carlo (kMC) simulations of borophene. Through extensive kMC simulations, new phases were discovered, such as the glass state of borophene, liquid borophene and borophene with large holes. A phase diagram of borophene is constructed to guide future experiments on borophene materials at high temperature
Small molecules based on 6,7-difluoroquinoxaline and thieno[3,2-b]thiophene for solution-processed solar cells
No full textFluorinated quinoxaline-based small molecules, SM1, SM2, and SM3, were developed as the donor materials for photovoltaic cells. The small molecules containing a 2,3-didodecyl-6,7-difluoroquinoxaline as the electron-deficient unit and thienothiophene as the electron rich units were synthesized by Stille coupling. The small molecules exhibit satisfactory thermal stability and a broad absorption band from 400 to 700 nm. The HOMO/LUMO energy levels of SM1, SM2, and SM3 were -5.70/-3.48, -5.57/-3.42, and -5.66/-3.59 eV, respectively. SM3 with the alkyl group at 4-position in terminal thiophene units has lower HOMO energy levels to increase the V-OC value
Engineering Pt Coordination Environment with Atomically Dispersed Transition Metal Sites Toward Superior Hydrogen Evolution
No full textMetal single-atom (SA) catalysts have attracted immense attention due to the high catalytic efficiency given by the desired coordination environment of each metal atom. Yet, engineering the local electronic structure of SAs and multi-atoms (MAs) still remains a challenge. Herein, an atomically dispersed catalyst comprised of Pt SAs, Pt-Pt/V dual-atoms, and small clusters supported on a vanadium and nitrogen co-doped carbon (VNC) (denoted as Pt@VNC) surface is synthesized. In the Pt@VNC, both V and Pt atoms are evenly distributed on the surface of N-doped carbon, while a few Pt atoms are linked to other Pt atoms via V, forming Pt clusters. The coordination structures of Pt atoms are modulated upon introducing atomically dispersed V sites (which generate small-sized Pt clusters) and V2O5 clusters, showing extraordinary activity for the hydrogen evolution reaction (HER). Benefiting from the low charge transfer resistance, i.e., fast reaction kinetics, due to the synergistic effect of SAs and clusters, the Pt@VNC demonstrates superior catalytic efficiency and robust durability for the HER. It requires an overpotential of only 5 mV at a current density of 10 mA cm(-2) and shows 15 times larger mass activity than the commercial 20 wt.% Pt/C catalyst. This novel catalyst-design strategy paves a new way for maximizing catalytic efficiency by optimizing the coordination structure of metal atoms
Organic-Additive-Derived Cathode Electrolyte Interphase Layer Mitigating Intertwined Chemical and Mechanical Degradation for Sulfide-Based Solid-State Batteries
No full textKeeping both the chemical and physical state of the electrode-electrolyte interface intact is one of the greatest challenges in achieving solid-state batteries (SSBs) with longer cycle lives. Herein, the use of organic electrolyte additives in the cathode electrolyte interphase (CEI) layer to mitigate the intertwined chemical and mechanical degradation in sulfide-based SSBs is demonstrated. Lithium difluorobis(oxalato)phosphate (LiDFBOP) and argyrodite (Li6PS5Cl) are used as a model system, with the LiDFBOP-derived CEI layer induced by irreversible oxidation above 4.12 V (vs Li+/Li) during the formation cycle exhibiting dual functions. This CEI layer retards the rate of chemical degradation between the cathode active particles and solid electrolytes at high charging potential and helps maintain intimate physical contact even at a low stack pressure of 0.75 MPa. The improved physical contact enables delivery of a high initial capacity, while chemical stability suppressing the sulfite or sulfate formation has a more dominant effect on the long-term cycle stability. This study presents a new perspective and strategies for designing cathode coating materials for sulfide-based SSBs beyond the typically used inorganic oxide materials