朝鮮初期雲山圖의 畫風

朝鮮初期雲山圖（靑山白雲圖）는 주로 宋代米氏의 雲林에 巨山을 折衷한 元代高克恭의 〈雲橫秀嶺圖〉와 같은 江南系雲山圖의 영향을 중심으로연구되어 왔다．그러나 한편으로 元末에 그려진 方從義의 〈雲山圖卷〉과 같은 華北系의 작품도 雲山圖라고 불리는데，本稿에서는 양식에 관계없이 이작품들이 雲山이라 불리는 이유가 米氏의 雲林이라는 모티프를 共有하기 때문이라 보았고 朝鮮初期에도 米氏의 雲林을 折衷한 다양한 畫風의 雲山圖가그려졌다는 것에 대해 考察했다．大和文華館 소장 〈雲山圖〉 6점은 高克恭系의 구도를 바탕으로 하면서도面的인 표현에 중점을 둔 高克恭의 〈雲橫秀嶺圖〉에 비해 線的인 樓閣이나樹枝法이 더해져 있는 점에서 元末雲山圖의 影響이 두드러지며 山容表現에는 元末盛懋의 간략화한 披麻皴과 胡椒點，그리고 元末의 前浙派的인 畫風 등을 折衷해서 재해석한 작품이라 보았다．南禪寺 소장 傳高然暉筆〈 雲山圖〉와〈 雪山圖〉는 그 山勢 표현이 元人筆〈靑山白雲圖〉（台北故宮博物院）에 보이는 元末의 前浙派的인 거친 筆致와유사하며，〈雲山圖〉의 높이 솟은 巨山과 雲林의 조합 등으로 볼 때 元末雲山圖의 영향을 받은 것으로 보인다．그리고 朝鮮初期에는 계절의 변화를 담은 山水畫가 유행하는데，특히 15세기 후반의 成宗期에 雲山圖와 雪山圖를함께 감상했다는 기록이 자주 보이는 점과 두 작품이 朝鮮初期山水畫에 흔히 보이는 對稱構圖를 취한 점에서 前浙派山水의 영향을 받은 15세기 후반의 朝鮮初期작품으로 보았다．九州國立博物館 소장〈 瀟湘八景圖〉의 煙寺暮鐘은 江南山水로 분류되는高克恭系의 화풍을 계승하고 있으나 細部描寫에는 15세기 후반부터 보이는朝鮮初期 특유의 短線點皴의 初期的인 특징이 보인다．그리고 이는 八景 중의 華北山水의 영향이 두드러진 작품에서도 사용되는데 이러한 점에서 短線點皴은 華北系뿐만 아니라 江南系山水에도 쓰였다는 것을 알 수 있다．또한이 그림은 煙寺暮鐘의 주요한 모티프인 樓閣이나 僧侶 등의 線的인 표현이거의 보이지 않는 것이 특이점인데，이것은 元末의 雲山圖보다는 古式인 高克恭의〈 雲橫秀嶺圖〉에 가까우며，그리고 여기에 江南山水의 廣闊한 水面表現이 折衷되어 있는 雲山圖로 이해된다．九州國立博物館 소장〈 瀟湘八景圖〉의 洞庭秋月은 華北系의 山容에 江南系의 드넓은 水面，거기에 雲林과 屋舍 등 雲山의 모티프를 折衷한 작품인데元末 張羽의“ 唐子華雲山歌” 등에서 이러한 折衷畫風을 읊고 있고，方從義의〈 雲山圖卷〉이 이러한 折衷樣式을 보이는 점에서 朝鮮初期에도 이러한 작품이 雲山圖라 불렸을 가능성이 높다는 것을 논했다．傳玉澗筆〈 雲山圖〉는 玉澗의 작품으로 전하던 것이나 近年에 朝鮮時代의작품으로 수정되었으며 本稿에서는 山稜의 點描나 山面의 線描 등이 短線點皴의 초기적인 특징이 보여 조선시대의 15세기말경의 작품이라 보았다．이상과 같이 朝鮮初期雲山圖는 다양한 화풍의 절충적인 경향이 보인다．이러한 경향은 元代復古主義에 의해 탄생한 折衷畫風인 高克恭系雲山에서 비롯한 것으로 그 思潮가 朝鮮初期畫壇에도 영향을 주어 다양하게 折衷되고 재해석된 朝鮮初期 특유의 雲山圖가 그려지게 된 것이다

Factors Affecting the Exfoliation of Graphite Intercalation Compounds for Graphene Synthesis

We investigate the mechanism of the intercalation-aided exfoliation of graphite using van der Waals force-corrected density functional theory (DFT) calculations. From a comparative study on various intercalation systems, we find that, depending on the intercalant species, the exfoliation energies vary significantly, not only due to the size of intercalants but also due to interactions with the host graphite. While it is generally perceived that an expanded interlayer distance with intercalants weakens the binding between graphene layers, as the van der Waals forces decrease, the calculations reveal that the intercalation of electronegative or electropositive intercalants (e.g., Li, K, F, Cl, and Br) result in a 1.5-5-fold higher exfoliation energy than pristine graphite due to additional binding forces from charge transfer between intercalants and graphene layers. Furthermore, we demonstrate that this additional binding force could be manipulated with cointercalation or neutral intercalants, which hints at effective exfoliation strategies with graphite intercalation compounds. This theoretical study broadens our understanding of the mechanism underlying graphite exfoliation and will facilitate development of more effective exfoliation strategies for other related layered materials

Extremely large, non-oxidized graphene flakes based on spontaneous solvent insertion into graphite intercalation compounds

Demand for an effective strategy for exfoliating layered materials into flakes without perturbing their intrinsic structure is growing. Herein, we introduce an effective fabrication method of large-sized non-oxidized graphene flakes (NOGFs) as a representative example of a general strategy using spontaneous insertion of exfoliating medium into a layered material. We fabricated a ternary graphite intercalation compound (t-GIC) with stoichiometry of KC24(THF)(2), and analyzed its morphology and electronic structure through experimental and computational approach. Interactions between the t-GIC and aprotic organic solvents with different polarities were investigated, where a unique swelling behavior was observed with dimethyl sulfoxide (DMSO). Based on the analysis of the phenomena, we demonstrate facile exfoliation of the t-GIC in polyvinyl pyrrolidone (PVP)-DMSO solution for fabrication of highly crystalline and large-sized NOGFs. The lateral size of the NOGFs ranges over 30 mu m, while the 98% having thickness below 10 layers. The NOGF film exhibits supreme electrical conductivity of 3.36 x 10(5) S/m, which is, to our best knowledge, the highest value for a thin conductive film made of graphene flakes. (C) 2018 Elsevier Ltd. All rights reserved.

Blue Graphene Quantum Dots with High Color Purity by Controlling Subdomain Formation for Light-Emitting Devices

As an alternative to Cd-free quantum dots (QDs), graphene quantum dots (GQDs) have potential because of their various advantages, such as color tunability, nontoxicity, cost effectiveness, and photostability. However, realization of a useful blue emission from GQDs requires a narrower full width at half-maximum (FWHM) and color purity in Commission Internationale de l'Eclairage (CIE) coordinates for display applications. These emission characteristics are strongly dependent on precise control of the sp(2) C subdomain, considered as the band-gap origin of GQDs. Here, we report a preparation for blue GQDs with improved color purity obtained from KC24 graphite intercalation compounds. The as-synthesized KC24-GQD exhibits high color purity with a photoluminescence FWHM of 70 nm and CIE coordinates of (0.159, 0.082), which can be attributed to the controlled oxidation of graphene by intercalated K ions with an arrangement of KC24 surrounding seven sp(2) C hexagons favorable for the formation of uniform subdomains. Furthermore, intrinsic emission-dominant fluorescence and phosphorescence from a powdered KC24-GQD-dispersed boron oxynitride matrix, as well as from solution-based KC24-GQD, prove its applicability to various light-emitting devices.

Molecular-level hybridization of single-walled carbon nanotubes and a copper complex with counterbalanced electrostatic interactions

Abstract Hybridization and wet processibility are highly desired development strategies for next-generation nanomaterials. In particular, the hybridization of carbon nanotubes (CNTs) and transition metals has been investigated for decades owing to the numerous advantages, such as high mechanical and electrical properties. However, manufacturing nano-hybridized CNTs/transition metals is complicated, and no studies have been reported on the dispersion and hybridization of transition metals with single-walled CNTs (SWCNTs) without any harsh or destructive methods due to the strong van der Waals forces. Herein, we demonstrate a one-step dispersion/hybridization of SWCNTs and a Cu-based complex and provide a mechanism derives from counterbalancing the electrostatic interactions via molecular-level charge transfer. The Cu-based complex-hybridized SWCNTs self-assemble and demonstrate suitable viscoelastic behaviors for various printing or coating processes. Finally, the nanostructured SWCNTs/Cu nanoparticle exhibits multifunctional electrothermal properties, electromagnetic interference shielding performances, and flexibilities. The proposed metal-complex-hybridized SWCNTs dispersions provide a wet process guideline for producing nanostructured electrodes

Moisture barrier composites made of non-oxidized graphene flakes

Graphene flakes (GFs) with minimized defects and oxidation ratios are incorporated into polyethylene (PE) to enhance the moisture barrier. GFs produced involving solvothermal intercalation show extremely low oxidation rates (3.17%), and are noncovalently functionalized in situ, inducing strong hydrophobicity. The fabricated composite possesses the best moisture barrier performance reported for a polymer-graphene composite. © 2015 Wile-VCH Verlag GmbH & Co. KGaA.