• 한국재료학회지
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• 제30권3호
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• pp.105-110
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• 2020

Cu/PET composite films are widely used in a variety of wearable electronics. Lifetime of the electronics is determined by adhesion between the Cu film and the PET substrate. The formation of an anisotropic nanostructure on the PET surface by surface modification can enhance Cu/PET interfacial adhesion. The shape and size of the anisotropic nanostructures of the PET surface can be controlled by varying the surface modification conditions. In this work, the effect of Cu/PET interface nanostructures on the failure mechanism of a Cu/PET flexible composite film is studied. From observation of the morphologies of the anisotropic nanostructures on plasma-treated PET surfaces, and cross-sections and surfaces of the fractured specimens, the Cu/PET interface area and nanostructure width are analyzed and the failure mechanism of the Cu/PET film is investigated. It is found that the failure mechanism of the Cu/PET flexible composite film depends on the shape and size of the plasmatreated PET surface nanostructures. Cu/PET interface nanostructures with maximal peel strength exhibit multiple craze-crack propagation behavior, while smaller or larger interface nanostructures exhibit single-path craze-crack propagation behavior.

• Structural Engineering and Mechanics
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• 제69권5호
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• pp.487-497
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• 2019

Rapid advances in the engineering applications can bring further areas to provide the opportunity to manipulate anisotropic structures for direct productivity in design of micro/nano-structures. For the first time, magnetic affected wave characteristics of nanosize plates made of anisotropic material is investigated via the three-dimensional bi-Helmholtz nonlocal strain gradient theory. Three small scale parameters are used to predict the size-dependent behavior of the nanoplates more accurately. After owing governing equations of wave motion, an analytical approach based harmonic series is utilized to fine the wave frequency as well as phase velocity. It is observed that the small scale parameters, magnetic field and wave number have considerable influence on the wave characteristics of anisotropic nanoplates. Due to the lack of any study on the mechanics of three-dimensional bi-Helmholtz gradient plates made of anisotropic materials, it is hoped that the present exact model may be used as a benchmark for future works of such nanostructures.

• 한국전기전자재료학회논문지
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• 제37권5호
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• pp.547-553
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• 2024

Precise control over the morphology of nanostructures is critical for tailoring their physical and chemical properties. This study addresses the challenge of developing a simple, integrated method for synthesizing both 1D and 2D colloidal Cu nanostructures in a single system, achieving successful tuning of their localized surface plasmon resonance (LSPR) properties. A facile hydrothermal synthesis utilizing potassium iodide (KI) and hexadecylamine (HDA) is presented for controlling Cu nanostructure morphologies. The key to achieving 1D nanowires (NWs) and 2D nanoplates (NPs) depends on the controlled adsorption of HDA molecules and iodide (I-) ions on specific crystal facets. Depending on the morphologies, the resultant Cu nanostructures exhibit tunable LSPR peaks from 558 nm [nanoplates (NPs)] to 590 nm [nanowires (NWs)]. These results pave the way for the scalable and cost-effective production of plasmonic Cu nanostructures with tunable optical properties, holding promise for applications in sensing, catalysis, and photonic devices.

• 한국고분자학회지:고분자과학과기술
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• 제21권3호
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• pp.247-250
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• 2010

• 전기화학회지
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• 제16권1호
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• pp.1-8
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• 2013

본 총설에서는 Si 비등방성 식각(anisotropic etching) 공정인 metal-assisted chemical etching(MAC etch 혹은 MACE) 분야 기본 원리, 중요 변수, 그리고 최근 연구 성과들을 정리하였다. 1990년에 최초로 Si 표면에 금속 촉매를 증착한 후 $H_2O_2$/HF 기반 식각을 진행하면 용액 중에서도 비등방성 식각을 통해 다양한 고종횡비(high aspect ratio) 나노구조를 형성할 수 있다는 것이 밝혀 졌다. 고가의 진공기반 장비가 필요한 건식 식각에 비해, 습식 식각을 통해서도 상대적으로 간편하고 경제적으로 종횡비가 큰 Si 마이크로/나노 구조를 만들 수 있게 되었다. 초기 연구들을 통해 MAC etch중 산화제가 촉매에 의해 환원되고, 촉매/Si 계면 근처의 Si 원자들이 선택적으로 식각/용해되어 수직 방향으로 촉매가 Si 기판을 파고 들어가며 비등방성 식각이 발생함이 밝혀졌다. MAC etch에 영향을 미치는 중요 변수로는 금속 촉매의 종류 및 모양, 식각액의 조성, Si기판의 도핑 농도이다. 또한 본 총설은 MAC etch에 의해 형성된 Si 나노 구조를 이용한 태양전지, 수소 연료, 리튬 이온 전지 등의 응용 분야를 다루었다.

• Steel and Composite Structures
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• 제27권2호
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• pp.201-216
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• 2018

In this paper, three-dimensional (3D) elasticity theory in conjunction with nonlocal strain gradient theory (NSGT) is developed for mechanical analysis of anisotropic nanoparticles. The present model incorporates two scale coefficients to examine the mechanical characteristics much accurately. All the elastic constants are considered and assumed to be the functions of (r, ${\theta}$, ${\varphi}$), so all kind of anisotropic structures can be modeled. Moreover, all types of functionally graded spherical structures can be investigated. To justify our model, our results for the radial vibration of spherical nanoparticles are compared with experimental results available in the literature and great agreement is achieved. Next, several examples of the radial vibration and wave propagation in spherical nanoparticles including nonlocal strain gradient parameters are presented for more than 10 different anisotropic nanoparticles. From the best knowledge of authors, it is the first time that 3D elasticity theory and NSGT are used together with no approximation to derive the governing equations in the spherical coordinate. Moreover, up to now, the NSGT has not been used for spherical anisotropic nanoparticles. It is also the first time that all the 36 elastic constants as functions of (r, ${\theta}$, ${\varphi}$) are considered for anisotropic and functionally graded nanostructures including size effects. According to the lack of any common approximations in the displacement field or in elastic constant, present theory can be assumed as a benchmark for future works.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.173-173
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• 2006

We have explored a strategy to control the supramolecular nano-structures self-assembled from rigid segments through attachment of flexible chains through microphase separation and anisotropic arrangement. Supramolecular structures formed by self-assembly of rigid building blocks can be precisely controlled from 1-D layered, 3-D bicontinuous cubic to 2-D cylindrical structures by systematic variation of the type and relative length of the respective blocks. Furthermore, depending on the individual molecular architectures, rigid building blocks self-assemble into a wide range of supramolecular structures such as honeycomb, disk, cylinder, helix, tube, barrel stave, and nano-cage.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.330-335
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• 2020

Silicon surface nanostructures, which can be easily prepared by electrochemical etching, have attracted considerable attention because of its useful physical properties that facilitate application in diverse fields. In this work, electrochemical and electrochemical-scanning tunneling microscopic (EC-STM) techniques were employed to study the evolution of surface morphology during the electrochemical etching of Si(111)-H in a fluoride solution. The results exhibited that silicon oxide of the Si(111) surface was entirely stripped and then the surface became hydrogen terminated, atomically flat, and anisotropic in the fluoride solution during chemical etching. At the potential more negative than the flat band one, the surface had a tendency to be eroded very slowly, whereas the steps of the terrace were not only etched quickly but the triangular pits also deepened on anodic potentials. These results provided information on the conditions required for the preparation of porous nanostructures on the Si(111) surface, which may be applicable for sensor (or device) preparation (Nanotechnology and Functional Materials for Engineers, Elsevier 2017, pp. 67-91).

• Macromolecular Research
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• 제12권6호
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• pp.564-572
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• 2004

Modem applications could benefit from multifunctional materials having anisotropic optical, electrical, thermal, or mechanical properties, especially when coupled with locally controlled distribution of the directional response. Such materials are difficult to engineer by conventional methods, but the electric field-aided technology presented herein is able to locally tailor electroactive composites. Applying an electric field to a polymer in its liquid state allows the orientation of chain- or fiber-like inclusions or phases from what was originally an isotropic material. Such composites can be formed from liquid solutions, melts, or mixtures of pre-polymers and cross-linking agents. Upon curing, a 'created composite' results; it consists of these 'pseudofibers' embedded in a matrix. One can also create oriented composites from embedded spheres, flakes, or fiber-like shapes in a liquid plastic. Orientation of the externally applied electric field defines the orientation of the field-aided self-assembled composites. The strength and duration of exposure of the electric field control the degree of anisotropy created. Results of electromechanical testing of these modified materials, which are relevant to sensing and actuation applications, are presented. The materials' micro/nanostructures were analyzed using microscopy and X-ray diffraction techniques.

• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.961-971
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• 2006

Shape controlled synthesis of inorganic nanocrystals is one of the important issues in materials chemistry due to their novel shape dependent properties. Although various shapes of nanocrystals have been developed, a systematic account on the shape control of these nanocrystals still remains an important subject in materials chemistry. In this article, we will overview the recent developments in the geometrical shape evolution of semiconductor and metal oxide nanocrystals obtained by nonhydrolytic synthetic methods. Many structurally unprecedented motifs have appeared as zero-dimesional (D) polyhedrons, one-D rods and wires, two-D plates and prisms, and other advanced shapes such as branched rods, stars, and inorganic dendrites. Important parameters which determine the geometrical shapes of nanocrystals are also illustrated. In addition, as a possible application of such nanocrystals for biomedical sciences, we further describe their utilizations for cancer diagnosis through nanocrystal-assisted magnetic resonance imaging (MRI).