2 research outputs found
ν¨ν΄μ μ΄μ©ν νλ©΄μ μ΄μ κ·Έ νμ©μ λν μ°κ΅¬
νμλ
Όλ¬Έ (λ°μ¬) -- μμΈλνκ΅ λνμ : 곡과λν ννμ물곡νλΆ(μλμ§νκ²½ ννμ΅ν©κΈ°μ μ 곡), 2021. 2. μ°¨κ΅ν.νλ©΄μ ꡬ쑰μ λλ ννμ μ±μ§μ λ°λΌ κ³ μ μ νΉμ±μ κ°μΌλ©°, μΈλΆμμ κ°ν΄μ§λ νμ μν΄ λ³νμ΄ μΌμ΄λκΈ°λ νλ€. νλ©΄μ λλ
Έ λ¨μλ‘ κ΄μ°° κ°λ₯ν μ μνλ―Έκ²½ μμ€ν
μ΄ λ°μ ν¨μ λ°λΌ νλ©΄μμ λ°μνλ μμ κ°μ νμμ λν μ°κ΅¬λ μ§λ μμ λ
κ° νλ°νκ² μ§νλμλ€. μ°μ, μκΈμμ΄ λ± μμ°κ³μμ λ°κ²¬λ λ
νΉν μ±μ§μ λνλ΄λ μ΄λ°μνλ©΄μ λ§μ΄ν¬λ‘ ꡬ쑰 μμ λ―ΈμΈν λλ
Έ κ΅¬μ‘°λ‘ μ΄λ£¨μ΄μ§ κ³μΈ΅ ꡬ쑰μ μν νΉμ±μΌλ‘ λνλλ νμμΈ κ²μ΄ λ°νμ§λ©΄μ μ΄λ₯Ό λͺ¨λ°©νμ¬ κ³΅νμ μΌλ‘ μ΄μ©ν΄λ³΄κ³ μ νμκ³ , νλ©΄μ λ°μνλ μ£Όλ¦, κ· μ΄ λ±μ ꡬ쑰μ μ€ν¨ νΉμ νμμΌλ‘ κ°μ£Όλμ΄ μ΄λ₯Ό μ μ΄νκ³ μ νμλ€.
ν¨ν°λμ νλ©΄μμ λ°μνλ νμμ 체κ³μ μΌλ‘ μ μ΄νκ³ λΆμν μ μλ νλ«νΌμ μ 곡νλ€. ν¨ν΄μ ν¬κΈ°, μ’
λ₯, κ°κ²© λ±μ λλ
Έ λ¨μλ‘ μμ λ‘κ² μ‘°μ νμ¬ νλ©΄μ ꡬ쑰μ νΉμ±μ μ μ΄ν μ μκΈ° λλ¬Έμ΄λ€. νλ©΄μ ν¨ν΄μ μ μνλ λ°©λ²μΌλ‘λ λΉκ³Ό λ§μ€ν¬λ₯Ό μ΄μ©ν κ΄ν 리μκ·ΈλνΌ, ννμ νΉμ±μ μ΄μ©ν μκ°, κ·Έλ¦¬κ³ PDMSλͺ°λλ₯Ό μ΄μ©ν μννΈ μνλ¦°ν
λ°©λ² λ±μ΄ μλ €μ Έ μλ€.
μ΄λ°μνλ©΄μ μκ°μΈμ μ 리, μκ°μΈμ μλμ°¨, μΌμ§ μλ νλ©΄ λ±κ³Ό κ°μ΄ μ°μ
μ μΌλ‘ μ΄μ© κ°μΉκ° λΆκ°λλ©΄μ μ΄λ₯Ό ꡬννκΈ° μν΄ λ€μν μ°κ΅¬κ° μ§νλμλ€. νΉν, κ³μΈ΅κ΅¬μ‘°λ₯Ό μ μν¨μ μμ΄ κ³΅νμ μΌλ‘ μ΄λ°μνμμ 체κ³μ λΆμνκ³ μ ν¨ν΄μ νμ©νλ λ°©λ²μ΄ μ μ©λμλ€. νμ§λ§, λλΆλΆ λ°νλ μ°κ΅¬λ κ³μΈ΅κ΅¬μ‘°λ₯Ό μ μνλ κ³Όμ μ΄ λ³΅μ‘νμ¬ μ°μ
μ μΌλ‘ μ΄μ©νκΈ°μλ νκ³κ° μμΌλ©° λ°λΌμ, μ΄λ°μνλ©΄μ κ°λ¨νκ² μ μνμ¬ μ°μ
λΆμΌμ μ μ©μν¬ μ μλ λ°©λ²μ λν μ°κ΅¬κ° νμν λμ΄λ€.
ννΈ, νλ©΄μ λ€μν ννμ νμ΄ κ°ν΄μ§λ©΄ μ΄λ₯Ό μνμν€κΈ° μν΄ λ³νμ΄ μΌμ΄λλ€. κ·Έ μ€ μΈμ₯μλ ₯μ μν΄ λ°μνλ κ· μ΄νμμ λΆκ·μΉμ μ΄κ³ μμ€ν
μ΄ λ³΅μ‘νκΈ° λλ¬Έμ μ‘°μ νκΈ° νλ€ λΏλ§ μλλΌ λλΆλΆ κ²°μ μΌλ‘ μ¬κ²¨μ§λ©΄μ. μ΄λ₯Ό λ°©μ§νκ³ μ νλ μ°κ΅¬μ μ§μ€λμ΄ μλ€. νΉν κ°λ νμκ³Ό κ°μ΄ μ©λ§€κ° μ¦λ°ν¨μ λ°λΌ λ°μνλ κ· μ΄μ κ³ λΆμ λ°λ§μμ λ°μνλ κ· μ΄νμλ³΄λ€ λμ± λ³΅μ‘νκ³ λΆκ· μΌνκ² νμ±λκΈ° λλ¬Έμ νμ¬κΉμ§ μ΄λ₯Ό μ μ΄νλ λ°©λ²μ λν μ°κ΅¬λ κ±°μ μ§νλμ§ μμ μ΄μ λν μ°κ΅¬κ° νμνλ€.
λ³Έ νμλ
Όλ¬Έμμλ νλ©΄μμ λ°μνλ νμ μ€ ν¨ν΄μ μ μ© νμ¬μ΄λ°μ νλ©΄κ³Ό κ· μ΄ μ μ΄μ κ΄ν 체κ³μ μΈ μ°κ΅¬λ₯Ό μ μνλ€. μ°μ
μ μΌλ‘ μ΄μ© κ°λ₯ν μ΄λ°μνλ©΄μ κ°λ¨νκ² μ μνλ λ°©λ²μ μ°κ΅¬νμκ³ , μ΄λ°μνλ©΄μ μ±μ§μ΄ λ€λ₯Έ ννμ ν¨ν΄μ κ°μΈνμ¬ λ¬Όλ°©μΈ μΆ©κ²© μνμ κΈ°κ³μ μ‘°μ μ λν μ°κ΅¬λ₯Ό νμλ€. λν κ²°μ μΌλ‘ μ¬κ²¨μ‘λ 건쑰 μ½λ‘μ΄λ λ°λ§μμ λ°μνλ κ· μ΄ νμμ ν¨ν΄μ μ΄μ©νμ¬ μ²΄κ³μ μΌλ‘ μ μ΄νμμΌλ©°, λ λμκ° κ· μ΄λ‘ μμ±λλ μ‘°κ°μ ν¬κΈ°κΉμ§ μμ λ‘κ² μ‘°μ νλ λ°©λ²μ μ μνμ¬ κ³΅νμ μΌλ‘ κ· μ΄μ μ μ©νκ² νμ©ν μ μλ μ°κ΅¬λ₯Ό μ μνλ€.
μ 1μ₯μμλ μ€νλ μ΄μμ€ν
μ νμ©νμ¬ λλ λ©΄μ μλ κ°λ¨ν μ΄λ°μνλ©΄μ ꡬννλ λ°©λ²μ λν μ°κ΅¬λ₯Ό μ μνμλ€. μμ¨μμλ λΉ λ₯Έ λ°μμ μ λνκΈ° μν΄ μνμ-μ¬μ΄μ¬ λ°μμ λμ
νμ¬ μ€λ¦¬μΉ΄λλ
Έμ
μμ λ°μΈλ, μ©λ§€λ‘ μ΄λ£¨μ΄μ§ μ½λ‘μ΄λ μ©μ‘μ μ μ‘°νκ³ κ° μμμ λΉμ¨μ΄ μ μ΄κ°, ν¬λͺ
μ±, νλ©΄ ꡬ쑰μ λ―ΈμΉλ μν₯μ μ°κ΅¬νμλ€. λν λ€μν νλ©΄μ μ μ©μμΌ λ²μ©μ μΈ νλ©΄μ μ΄λ°μν¨κ³Όλ₯Ό λνλ΄λ κ²μ νμΈνμλ€.
μ 2μ₯μμλ μ΄λ°μνλ©΄μ μΉμμ±μ κ°μ§ λΉλμΉ ννμ ν¨ν΄μ κ°μΈμμΌ λ¬Όλ°©μΈμ κ±°λμ΄ μ‘°μ κ°λ₯ν νλ©΄μ μ μνμλ€. κΌμ§μ μ΄ μλ ν¨ν΄μ μ€κ³νμ¬ λ¬Όλ°©μΈμ΄ νλ©΄μ 좩격νκ³ λ€μ νμ΄ μ€λ₯Ό λ, κΌμ§μ λ°©ν₯μΌλ‘ νμ΄ μ€λ₯΄λλ‘ μ λνμλ€. ν¨ν΄μ κ°λμ μΆ©λ 거리λ₯Ό μ‘°μ νμ¬ λ°©ν₯μ±μ μ λμ μν₯μ μ£Όλ μμΈμ μ°Ύμλ΄μκ³ , μ΄λ₯Ό κΈ°ννμ μ΄λ‘ κ°κ³Ό λΉκ΅νμ¬ μ°¨μ΄κ° μλ κ²μ νμΈνμλ€. μ΄μ κ°μ νλ©΄μ 물리μ κ΅¬μ‘°κ° μλ ννν νλ©΄μμλ ννμ ν¨ν΄μ μν΄ λ¬Όλ°©μΈμ κ±°λμ΄ μ‘°μ λμκ³ , λμκ° λ¬Όλ°©μΈμ κΌμ§μ κ³Ό κ°μ νΉμ μμΉμ λͺ¨μ μ μλ€λ κ²μ νμΈνμλ€.
μ 3μ₯μμλ μ 1μ₯μμ νλ©΄μ μ μνλ κ³Όμ μμ λ°μν κ· μ΄ νμμ λ§μ΄ν¬λ‘ν¨ν΄μ μ΄μ©νμ¬ μ μ΄νλ λ°©λ²μ μ μνμλ€. TiO2λ‘ μ΄λ£¨μ΄μ§ μ½λ‘μ΄λ νλ¦μ μννΈ μνλ¦°ν
κΈ°λ²μ μ΄μ©νμ¬ νλ¦¬μ¦ νΉμ νΌλΌλ―Έλ λ§μ΄ν¬λ‘ν¨ν΄μ κ°μΈμν€κ³ , μκ²° κ³Όμ μ ν΅ν΄ νλ¦μ μ κΈ°λ¬Όμ λͺ¨λ μ κ±°νλ©΄ νλ¦μ λΆνΌ μμΆμ΄ λ°μλκ³
μ€νΈλ μ€λ κ° ν¨ν΄μ κ°μ₯μ리μ μ§μ€λκ³ κ· μ΄μ΄ μ΄κ³³μ μμ±λλλ‘ μ λνμλ€. κ· μ΄ μ§μ€ νμμ μ λλ νλ¦μ λκ», λλ
Έ μ
μμ ν¬κΈ°, κ°μ΄ μλμ μν₯μ λ°λ κ²μ νμΈνμλ€. νΉν νλ¦ λκ»λ μμ±λλ κ· μ΄ μ‘°κ°μ λ©΄μ μλ μν₯μ μ£ΌμμΌλ©°, κ° κ· μ΄ μ‘°κ°μ μ μ¬κ°ν νΌλΌλ―Έλλ‘ κ΅¬μ±λ μ₯μ μ νμ©νμ¬ λ©΄μ μ μ½κ² μ λν νμκ³ , νλ¦ λκ»μ λ©΄μ μ΄ κ°λ μ€μΌμΌλ§ κ΄κ³λ₯Ό νμΈνμλ€.
μ 4μ₯μμλ κ· μ΄μ μ μ΄νλ κ²μμ λ λμκ° κ· μ΄ μ‘°κ°μ ν¬κΈ°κΉμ§ μμ λ‘κ² μ‘°μ νμ¬ μ‘°κ°μ κΈ°νμμ λΌμ΄λ΄μ΄ λ§μ΄ν¬λ‘ λΈλ‘μ λλμΌλ‘ λ§λ€ μ μλ νλ«νΌμ κ°λ°νμλ€. μλ‘ λ€λ₯Έ λμ΄λ₯Ό κ°λ λΌμΈ νΉμ νλΌ ν¨ν΄μ΄ μλ κΈ°νμ μ¬μ©νμ¬ κΈ°νμ΄ κ· μ΄μ λ―ΈμΉλ μν₯μ λΆμνμλ€. μ μ΄λ μ¬μ΄μ¦μ κ· μ΄ μ‘°κ°μ κΈ°νμμ λΌμ΄λ΄μ΄ λ§μ΄ν¬λ‘λΈλ‘μΌλ‘ μ¬μ©ν μ μμκ³ , μ΄λ₯Ό νμ©νλ λ°©λ²μ μ μνμλ€.
μ΄λ¬ν μ°κ΅¬ κ²°κ³Όλ ν¨ν΄μ νμ©νμ¬ νλ©΄μ μ μ΄ν μ μλ λ°©λ²μ μ μνκ³ , μ΄λ₯Ό ν΅ν΄ κ²°μ μΌλ‘ μ¬κ²¨μ‘λ κ· μ΄ νμμ 곡νμ μΌλ‘ μμ© κ°λ₯νλλ‘ μμμ λν μ€ κ²μ κΈ°λνλ€.The surface properties are affected by the physical structures or chemical characteristics of the surface. As the electron microscope system advanced to allow observing in nanoscale, the fundamental researches of surface properties conducted last few decades. The superhydrophobic surfaces, which was unique property found in lotus leaf, was revealed due to the effect of hierarchical structure, many researchers try to imitate them. Patterning method was introduced to fabricate hierarchical structure to systematic analysis, however, most researches showed limitations for industrial application due to the complicated process. It was necessary to study how to create supernumerary surfaces by implementing hierarchies in a simple way.
Meanwhile, mechanical instabilities such as wrinkles, folds and cracks arise when the surface is subjected to various kind of stresses. Among them, the crack phenomenon caused by tensile stress regarded as defect due to its random generation, research was focus on to prevent them. Especially in the drying colloidal film system, there has been little research on how to control it so far, because it is more complex and unevenly formed than the crack phenomenon occurring in the polymer thin film.
Pattering provides a platform for systematically controlling and analyzing these phenomena occurred on surfaces. This is because the structural characteristics of the surface can be controlled by freely adjusting the size, type, and spacing of patterns in nano unit. The patterning methods are known as photo lithography, etching and soft imprinting, etc.
This dissertation presents a systematic study of superhydrophobic surface and crack manipulation by applying pattern. A simple method to fabricate hierarchical structure was studied for applying industrial field and mechanical control of drop impact dynamics on patterned surfaces was analyzed. The surface crack in desiccation film was controlled by stress localization effect induced by micropatterns. Furthermore, we controlled the size of crack fragments with substrate effect to fabricate homogeneous microblocks and suggest that crack can be usefully utilized in the engineering field.
In Chapter 1, we presented a study on fabricating method to transparent superhydrophobic surfaces in large areas. In order to induce a rapid reaction even at room temperature, epoxy-thiol click reaction was introduced into the binder to manufacture a colloid solution consisting of silica nanoparticles, binders and solvents. We investigated the effect of the proportion of each element on the contact angle, transparency and surface structure. Finally, we suggest the spray coating to applicable on a universal surface to coating with superhydrophobicity.
In Chapter 2, an asymmetrical chemical pattern with hydrophilic properties was imprinted on the surface to control droplet after impacting the surface. A pattern with vertex was designed to induce droplets bouncing toward vertex after impacting the surface. By adjusting the angle of the pattern and the impacting distance from the vertex, we find factors that influence the degree of directionality, and compare them with geometric theoretical values. This idea provided the platform to collect the droplets on flat surface without any physical patterns in surface.
In Chapter 3, we studied the method of controlling random cracks generated during surface fabrication process in Chapter 1 to well-ordered cracks via micropatterns (prisms and pyramids). Micropatterned films were fabricated by the soft imprinting technique with wet TiO2 nanoparticle pastes, followed by calcination to remove organic components. During the calcination, the volume shrinkage occurred in film and stress was concentrated on the edges of each pattern induced cracks to be produced. The degree of stress localization effect was affected by film thickness, nanoparticle size, and heating rate. In particular, film thickness also affected the area of the crack fragments. Utilizing the advantages of our experimental system, we could use a pyramid as a unit to accurately quantify the area of fragments by simply counting the number of pyramids in isolated cracks to identify the scaling relationship between film thickness and area.
In Chapter 4, we developed a platform to fabricate various size of pyramidal microblocks by cracking over patterned surfaces. We studied the substrate effect on control cracks and manipulate the fragmentation of TiO2 microscopic pyramids by cracking on prepatterned substrates that have different depths in the substrate. The homogeneous mesoporous microblocks with multifunctionality and various sizes for versatile applications by detaching them from the substrate. This crack engineering method can be used to economically produce a large number of mesoporous microblocks with tunable sizes and functionalities.
We believe these studies suggest the ways to control surface properties by utilizing patterns and can give guide to the new strategies on manipulating cracks in desiccation crack system.Contents
Chapter 1. Large-Scale Transparent Hydrophobic Surfaces Fabricated by Spray Coating Formulation 1
1.1. Introduction 1
1.2. Experimental Section 3
1.3. Results and Discussion 5
1.3.1. Design of the One-Step Transparent Superhydrophobic Coating Formulation through Spray Process 5
1.3.2. Development of Rapid Curing Binder System in Ambient Condition through Thiol Epoxy Reaction 7
1.3.3. Effects of the Ratio of Binder and Silica NPs on Surface Morphology and Transparency 10
1.3.4 Demonstrate to the Universal Surface by Spray Coating Formulation 15
1.4. Conclusion 17
Chapter 2. Mono Directional Bouncing of Droplets Impacting on Asymmetric Hydrophilic Patterned Surfaces 18
2.1. Introduction 18
2.2. Experimental Section 20
2.3. Results and Discussion 22
2.3.1. Fabrication of Vertex Hydrophilic Patterns on Hydrophobic Surfaces 22
2.3.2. Drop Impacting on Asymmetric Hydrophilic Patterned Surfaces 24
2.3.3. Mechanical Analysis 29
2.4. Conclusion 33
Chapter 3. Control of Surface Cracks by Stress Localization Induced Micropatterns 34
3.1. Introduction 34
3.2. Experimental Section 36
3.3. Results and Discussion 40
3.3.1. Imprinting Effect on Crack Manipulation by Stress Localization Effect 40
3.3.2. Degree of Stress Localization Effect in Film Thickness 45
3.3.3. Effect of Temperature on Crack Propagation 49
3.3.4. Effect of Particle Size and Heating Rate on Critical Cracking Thickness(CCT) 51
3.3.5. Analysis of Crack Fragment Phenomena above the Critical Film Thickness 54
3.4. Conclusion 64
Chapter 4. Tiled Microblocks Obtained on Crack Template with Substrate Patterns 65
4.1. Introduction 65
4.2. Experimental Section 68
4.3. Results and discussion 71
4.3.1. Crack Manipulation Induced by Substrate Effect 71
4.3.2. Control of the Crack Initiation Tips Depending on the Substrate Effect 80
4.3.3. Fabrication of Size and Porosity Controlled Microblocks 84
4.3.4. Multifunctional TiO2 Microblocks 90
4.4. Conclusion 93
Conclusions 94
Bibliography 97
κ΅λ¬Έ μ΄λ‘ 109Docto