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All-Polymer Photodetectors with n-Type Polymers Having Nonconjugated Spacers for Dark Current Density Reduction

MACROMOLECULES 2022年第21期55卷 9489-9501页

作者： Kim, Hyeokjun Kang, Jinhyeon Park, Jaehee Ahn, Hyungju Kang, In-Nam Jung, In Hwan Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea POSTECH Pohang Accelerator Lab Pohang 37673 South Korea Catholic Univ Korea Dept Chem Bucheon Si 14662 South Korea

Recently, all-polymer-based p-n bulk heterojunction organic photodiodes exhibited a high photocurrent density (Jph) through the state-of-the-art synthesis in n-type conjugated polymers. However, in the organic photodetector (OPD) application, the on-off ratio (Jph/dark current density (Jd)) is a performance-determining parameter;thus herein we focused on effectively increasing the on-off ratio by lowering the Jd of all-polymer OPDs. We developed four n-type polymers, with nonconjugated spacers, which effectively suppressed the Jd of the devices;the increased insulating properties and excellent hole-blocking properties under dark conditions aided Jd suppression. Moreover, breaking the pi-conjugation of the n-type polymers, by adding short bulky nonconjugated spacers, effectively increased Jph and decreased Jd in relation with those upon the addition of long flexible alkyl spacers. Hence, the OPDs based on the n-type polymer with a nonconjugated spacer exhibited a high specific detectivity of >1012 Jones and a -3 dB cutoff frequency of 219 kHz. Notably, they also displayed ultrafast rising and falling response times of 2 and 9 mu s, respectively, at -2 V.

关键词： Cutoff frequency

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Evaluation method for microscale mechanical properties of an epoxy resin

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POLYMER TESTING 2024年 135卷

作者： Kim, Eonji Yun, Hwanhui Lee, Jinhee Lee, Wang-Eun Heo, Kyuyoung Jung, In Hwan Song, In Young Korea Res Inst Chem Technol Reliabil Assessment Ctr Daejeon 34114 South Korea Hanyang Univ Dept Organ & Nano Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea

This study offers a detailed quantitative evaluation of microscale properties of polymers utilizing the surface and interfacial cutting analysis system (SAICAS) technique. The investigation focuses on the formation of the primary shear zone (PSZ) during cutting, leading to plastic deformation and subsequent chip curling. This research explores various cutting thicknesses, each demonstrating unique chip formation, and applies a lubricant to mitigate friction noise and stabilize chip formation. An in-depth analysis of force geometries is performed to gain insights into chip formation. The shear strength and shear viscosity are calculated using relevant equations, thus enabling the quantitative characterization of the viscoelastic behavior of polymers. Remarkably, the polymers exhibit shear thinning behavior, where their resistance to shear decreases as the shear rate increases. The shear viscosity-shear rate plot follows the Ostwald-de Waele relationship, indicative of plastic flow behavior. The viscoelastic characteristics were validated by comparing the values calculated based on Atkins's theory with the quantified values. Then, the physical meaning of those values were discussed. This study facilitates the direct measurement of mechanical properties in solidified form of the polymer, offering a more precise representation than traditional test piece measurements. In addition, shear viscosity determination of cross-linked materials without pretreatment is achieved, broadening the scope of material analysis through quantitative comparisons.

关键词： Mechanical properties of polymers Micro-scale analysis Shear viscosity of thermoset polymers

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Overlapping and Distinct Physical and Biological Phenotypes in Pure Frailty and Obese Frailty

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BIOSCIENCE REPORTS 2024年第11期44卷 BSR20240784页

作者： Ji, Fujue Park, Ji Hyun Rheem, Hyeonseung Kim, Jong-Hee Hanyang Univ Coll Performing Arts & Sport Div Sport Ind & Sci Major Sport Sci 222 Wangsimni Ro Seoul South Korea Hanyang Univ BK21 FOUR Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea

Background: Pure frailty and obese frailty are common types of frailty syndrome. However, the overlapping and distinct characteristics between pure frailty and obese frailty remain unclear. This study aims to reveal the overlapping/distinct physical and biological phenotypes of pure frailty and obese frailty, providing theoretical support for their prevention, diagnosis, and treatment. Method: Mice were fed either a normal or high-fat diet and assessed at 20 months of age. They were assigned to one of the four groups: control, obesity, pure frailty, and obese frailty. Grip strength, walking speed, physical activity, endurance, and body weight were measured to determine pure frailty and obese frailty. Physical and biological phenotypes were assessed. Results: Distinct physical phenotypes were observed between pure frailty and obese frailty in terms of body weight, lean mass, fat mass, fat mass in tissue, grip strength, endurance, and physical activity, while walking speed overlapped. In biological phenotypes, levels of Smad2/3, FoxO3a, P62, LAMP-2, and cathepsin L expression were distinct, while AKT, p-AKT, mTOR, p-mTOR, p-Smad2/3, p-FoxO3a, Beclin-1, ATG7, and LC3 overlapped. Conclusion: Distinct physical phenotypes observed in obese frailty are primarily attributable to the effect of obesity, with further impairment of muscle function resulting from the combined effects of frailty syndromes and obesity. Pure frailty and obese frailty share overlapping biological phenotypes, particularly in the regulation of muscle protein synthesis. Moreover, the interaction between obesity and frailty syndromes gives rise to both overlapping and distinct biological phenotypes, especially in the regulation of specific degradation signaling proteins.

关键词： frailty obesity phenotype

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Hierarchical Nanoporous N-Doped Carbon for Enhanced Rate Performance of Lithium-Ion Battery Anodes

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ACS APPLIED NANO MATERIALS 2024年第15期7卷 17305-17315页

作者： Bansal, Neetu Agrim, Kavya Prakash Bohra, Aamir Mushtaq Ahamad, Tansir Park, Changyong Ahn, Heejoon Salunkhe, Rahul R. Indian Inst Technol IIT Jammu Dept Phys Mat Res Lab Jammu 181221 J&K India King Saud Univ Coll Sci Chem Dept Riyadh 11451 Saudi Arabia Hanyang Univ Dept Organ & Nano Engn Human Tech Convergence Program Seoul 04763 South Korea

At the nanoscale, the graphitic degree, surface area, and heteroatom doping are primary properties of any carbon material that influences anode performance for Li-ion battery (LIB) applications. The simultaneous control over nanostructured properties such as doping and surface area at the nanolevel remains challenging for achieving fast operating LIB. Here, we demonstrate a study on nitrogen-doped hierarchically nanoporous carbon (HNC) materials with specific dopant concentrations and tunable surface areas designed strategically via a dual-templating approach. The 3D nanoporous microflowers provide pathways to the lithium reservoir for fast charge-discharge. We explore the effect of different ammonia concentrations on nitrogen doping levels and the surface area of HNCs. Our findings reveal that consistently high surface area and excess nitrogen doping levels do not confer benefits. High-rate battery performance can be achieved at the expense of any of these properties. Using optimized HNC, we achieved a high-rate performance of 357 mAh g(-1) at 2 A g(-1) and approximately 87% stability retention after 600 cycles, showcasing its potential for LIB applications.

关键词： nanoporous carbon anode lithium doping performance templating method solid-electrolyte interphase storage

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Facile Preparation of a Wet-Laid Based Graphite Nanoplate and Polyethylene Terephthalate Staple Fiber Composite for Textile-Structured Rollable Electronics

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JOURNAL OF ELECTRONIC MATERIALS 2021年第9期50卷 5433-5441页

作者： Sun, Kyung Chul Ali, Mumtaz Anjum, Aima Sameen Noh, Jung Woo Sahito, Iftikhar Ali Jeong, Sung Hoon Hanyang Univ Dept Organ & Nano Engn Human Tech Convergence Program Seoul 04763 South Korea Natl Text Univ Fac Engn & Technol Weaving Dept Faisalabad 37610 Pakistan Korea Inst Ind Technol Tech Text R&D Grp Ansan 15588 South Korea Mehran Univ Engn & Technol Dept Text Engn Jamshoro 76062 Pakistan

Rollable and flexile electronics, especially textile-structured batteries and solar cells, are in high demand. Therefore, the wet-laid process for producing nonwoven textiles has gained much interest because of its processing ease and scalability for production. A unique electrically conductive nonwoven material, developed based on a scalable composite of graphite nanoplates and polyethylene terephthalate (PET) staple fibers, is proposed for textile-structured rollable electronics in this work. To optimize the proposed structure, PET and graphite composites are designed by decorating the surface of the PET nonwoven material with graphite nanoplates to enhance its electrical performance and electron pathways, and for this purpose different weight percentages of graphite fillers were incorporated into the PET fibrous matrix. The proposed graphite-PET nonwoven composites show excellent electrical and thermal conductivities, suitable flexibility for electrical devices and the potential for use in wearable devices. The results prove that the proposed unique conductive nonwoven material and its performance can be promising for next-generation rollable e-textiles.

关键词： E-textiles graphite PET wet-laid electrical conductivity

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Value-Addition of Wastes from Petroleum Refining Process: Sulfur-Rich Polymers for Sustainable and High-Performance Optical and Energy Applications

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ACCOUNTS OF MATERIALS RESEARCH 2024年第5期5卷 625-639页

作者： Cho, Woongbi Kim, Sungsu Wie, Jeong Jae Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea Hanyang Univ Dept Chem Engn Human Tech Convergence Program Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol Seoul 04763 South Korea SUNY Coll Environm Sci & Forestry Dept Chem Engn Syracuse NY 13210 USA SUNY Coll Environm Sci & Forestry Michael M Szwarc Polymer Res Inst Syracuse NY 13210 USA

The petrochemical industry plays a pivotal role in the manufacturing process of petrochemical products by transforming crude oil into monomers of synthetic polymers used to produce a wide range of commercial products. However, the generation of elemental sulfur, a significant byproduct of the petroleum refining process, has raised substantial environmental concerns as the volume of petroleum refining is increasing to meet rapidly growing energy consumption and demand for petrochemical products. Due to hydrodesulfurization, 7 million tons of elemental sulfur is produced as an annual surplus, which exceeds the amount used for rubber vulcanization, fertilizer production, and sulfuric acid manufacturing. If, however, we can upcycle this abundant resource for high-value applications, the mass production of high-purity elemental sulfur might provide huge economic benefits. In 2013, the first successful research study in synthesizing sulfur-rich polymers (SRPs) with a high sulfur content of up to 90 wt % was reported, employing inverse vulcanization. Unlike carbon-based polymers, SRPs demonstrate remarkable infrared (IR) transparency, which allows us to usher in a new era of polymer-based IR optics. Furthermore, SRPs also show high potential as sustainable and high-performance triboelectric materials due to the highest electron affinity of elemental sulfur excluding halogen atoms. Hence, SRPs have garnered significant interest in practical applications, such as IR thermal imaging and triboelectric energy harvesting. In this Account, we highlight our recent progress in upcycling SRPs into the aforementioned practical applications, such as IR polarizers and triboelectric nanogenerators (TENG) toward value-addition of elemental sulfur. First, we will discuss strategies to enhance thermo-mechanical properties of SRPs such as the glass transition temperature (T-g), cross-linking density, and elastic modulus without significant deterioration of IR transparency. Despite these uni

关键词： Infrared light Layers Nanogenerators Sulfur Thickness

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Modified nanoporous zeolites on a biodegradable polymer film with excellent hydrophobicity, ethylene gas adsorption, and antibacterial activity through surface charge accumulation

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CHEMICAL ENGINEERING JOURNAL 2024年 498卷

作者： Lee, Jiwoo Kong, Taewoong Park, Jungchul Han, Seunghye Choi, Hyeongsub Sun, Jingzhe Choi, Sanghwan Park, Jong-Jin Chonnam Natl Univ Dept Polymer Sci & Engn 77 Yongbong Ro Gwangju 61186 South Korea Jeonnam Technopk Chem Ind Ctr Jeollanam Do 59631 South Korea Hanyang Univ Dept Clothing & Text Human Tech Convergence Program Seoul 04763 South Korea Epolytech Co Ltd Yeosu Si 59779 Jeollanam Do South Korea

The high specific surface area and large pore volume of nanoporous zeolites (NZs) were utilized to impart a biodegradable polymer film with superhydrophobicity, ethylene gas adsorption capability, and active antibacterial activity. NZs were synthesized by using organic silanes via a sol-gel method. They were then dispersed on a biodegradable blended PPP [poly(lactic acid) (PLA)/poly butylene succinate (PBS)/poly butylene adipate terephthalate (PBAT)] film to enhance its mechanical properties and control water repellent. The hydrophobicity of the organic silanes on the zeolite surface gradually increased according to their length. The film prepared by utilizing octadecyltriethoxysilane (ODTES) was superhydrophobic with a contact angle 142.6 degrees. The porous structure of the PPP with attached ODTES-NZs impeded the release of accumulated charges generated through friction, thereby yielding excellent output voltage when applying friction periodically. The output performance of the PPP-ODTES-NZs film was measured to be 723 V when a positive charge was injected into the film, which was about 3.1 times higher than the output performance of the PPP film without surface modification. The accumulated positive charges provided excellent antibacterial efficacy against externally introduced bacteria. Our approach of attaching ODTES-NZs to a blended polymer provides a multifunctional biodegradable film (ethylene gas adsorption, water repellent, and antibacterial activity via positive charge accumulation) with excellent food-storage capability.

关键词： Nanoporous zeolite Ethylene gas adsorption Biodegradable Antibacterial Surface charge

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How to measure social capital in an online brand community? A comparison of three social capital scales

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JOURNAL OF BUSINESS RESEARCH 2021年 131卷 652-663页

作者： Jeong, So Won Ha, Sejin Lee, Kyu-Hye Inha Univ Sch Global Convergence Studies 100 Inha Ro Incheon 22212 South Korea Univ Tennessee Dept Retail Hospitality & Tourism Management 1215 W Cumberland Ave Knoxville TN 37996 USA Hanyang Univ Dept Clothing & Text Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea

Despite that social capital is widely used to explain social interactions and networking on social media, there is no consensus on the measurement of social capital, and successful assessment is difficult. To address this issue, this research presents an empirical comparison of three different social capital scales in the context of online brand communities: Chiu et al.'s six sub-dimensional model (2006), Lin and Lu's three-dimensional model (2011), and Williams's two-dimension model (2006). Results indicate that social capital in an online brand community environment mainly consists of three dimensions, including social interaction ties, trust, and shared value, lending support for Lin and Lu's scale over the others. Our investigation of social capital scales provides managerial and theoretical implications by identifying and validating context-specific measures of social capital.

关键词： Social capital Social media Online brand communities Commitment

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Tracking the thermal dynamics of Ti3C2Tx MXene with XPS and two-dimensional correlation spectroscopy

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APPLIED PHYSICS LETTERS 2023年第21期122卷 211601-211601页

作者： Eom, Wonsik Shin, Hwansoo Han, Tae Hee Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea

MXenes are a class of two-dimensional materials with potential applications in the fields such as thermal management and high-temperature materials. In this study, the transitions of Ti3C2Tx MXene are investigated during thermal annealing via x-ray photoelectron spectroscopy and two-dimensional correlation spectroscopy. The thermal evolution of MXene samples occurs as two distinct processes in different temperature regions: process I (from 25 to 500 ?) and process II (from 500 to 777 ?). In process I, the terminal groups of MXene are reduced, and fluorine (-F) terminal groups are released. Four different pathways are identified with C-Ti-O and C-C as probable final products. In process II, the reaction resulting in the removal of -F species and decomposition of the Ti3C2 region in the MXene is observed. These results provide insight into the thermal decomposition behavior of Ti3C2Tx MXene, which can assist in the design of MXene-based materials with specific functionalities.

关键词： X ray photoelectron spectroscopy

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Surface nitrided MXene sheets with outstanding electroconductivity and oxidation stability

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MATERIALS HORIZONS 2023年第11期10卷 4892-4902页

作者： Eom, Wonsik Shin, Hwansoo Jeong, Woojae Ambade, Rohan B. Lee, Hyeonhoo Han, Tae Hee Hanyang Univ Dept Organ & Nano Engn Human Tech Convergence Program Seoul 04763 South Korea Univ Illinois Dept Mech Sci & Engn Champaign IL 61801 USA Hanyang Univ Res Inst Ind Sci Seoul 04763 South Korea Khalifa Univ Aerosp Res & Innovat Ctr Abu Dhabi 127788 U Arab Emirates

Two-dimensional Ti3C2Tx MXenes are promising candidates for a wide range of film- or fiber-based devices owing to their solution processability, high electrical conductivity, and versatile surface chemistry. The surface terminal groups (T-x) of MXenes can be removed to increase their inherent electrical performance and ensure chemical stability. Therefore, understanding the chemical evolution during the removal of the terminal groups is crucial for guiding the production, processing, and application of MXenes. Herein, we investigate the effect of chemical modification on the electron-transfer behavior during the removal of the terminal groups by annealing Ti3C2Tx MXene single sheets under argon (Ar-MXene) and ammonia gas (NH3-MXene) conditions. Annealing in ammonia gas results in surface nitridation of MXenes and preserves the electron-abundant Ti3C2 structure, whereas annealing MXene single sheets in Ar gas results in the oxidation of the titanium layers. The surface-nitrided MXene film exhibits an electrical conductivity two times higher than that of the Ar-MXene film. The oxidation stability is quantified by calculating the oxidation rate constants for severe reactions with H2O2. The surface-nitrided MXene is 13 times more stable than Ar-MXene. The investigation of MXene single sheets provides fundamental insights that are valuable for designing electrically conductive and chemically stable MXenes. Annealing MXenes in ammonia enhances electrical conductivity and oxidation resistance by nitriding the surface. The nitridation effect on single and multi-sheet of MXene including the chemical reaction for terminal removal was investigated.

关键词： Ammonia

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