Plasma Nanoscience: from Nano-Solids in Plasmas to Nano-Plasmas in Solids

The unique plasma-specific features and physical phenomena in the organization of nanoscale solid-state systems in a broad range of elemental composition, structure, and dimensionality are critically reviewed. These effects lead to the possibility to localize and control energy and matter at nanoscales and to produce self-organized nano-solids with highly unusual and superior properties. A unifying conceptual framework based on the control of production, transport, and self-organization of precursor species is introduced and a variety of plasma-specific non-equilibrium and kinetics-driven phenomena across the many temporal and spatial scales is explained. When the plasma is localized to micrometer and nanometer dimensions, new emergent phenomena arise. The examples range from semiconducting quantum dots and nanowires, chirality control of single-walled carbon nanotubes, ultra-fine manipulation of graphenes, nano-diamond, and organic matter, to nano-plasma effects and nano-plasmas of different states of matter.Comment: This is an essential interdisciplinary reference which can be used by both advanced and early career researchers as well as in undergraduate teaching and postgraduate research trainin

Applications of plasma-liquid systems : a review

Plasma-liquid systems have attracted increasing attention in recent years, owing to their high potential in material processing and nanoscience, environmental remediation, sterilization, biomedicine, and food applications. Due to the multidisciplinary character of this scientific field and due to its broad range of established and promising applications, an updated overview is required, addressing the various applications of plasma-liquid systems till now. In the present review, after a brief historical introduction on this important research field, the authors aimed to bring together a wide range of applications of plasma-liquid systems, including nanomaterial processing, water analytical chemistry, water purification, plasma sterilization, plasma medicine, food preservation and agricultural processing, power transformers for high voltage switching, and polymer solution treatment. Although the general understanding of plasma-liquid interactions and their applications has grown significantly in recent decades, it is aimed here to give an updated overview on the possible applications of plasma-liquid systems. This review can be used as a guide for researchers from different fields to gain insight in the history and state-of-the-art of plasma-liquid interactions and to obtain an overview on the acquired knowledge in this field up to now

Development of new nanostructured electrodes in Microbial Fuel Cells (MFCs)

The aim of my thesis work is to investigate new nanostructured materials, obtained by the electrospinning technique, in order to design 3D arrangement of the electrodes, leading thus to improve the energy efficiency of energy production devices, such as microbial fuel cells (MFCs). The carbon nanofibers reveal to be the most promising material in the field of bio electrochemistry; in fact, up to now the best performing microbial fuel cells are fabricated using carbon and carbon based material electrodes. To further enhance the performances of bio anodes and bio cathodes, a set of properties are then required to be overcome, such as a proper surface morphology and chemistry, good biofilm adhesion and electron transfer, and a good electrical conductivity. This work aims to demonstrate that the electrospun nanofibers own all the necessary properties, revealing themselves as the most innovative and promising structures for anodes and cathodes for microbial fuel cells. The nanofibers ensure all the properties listed above; in particular, during my Ph.D. I have investigated and studied the carbon based nanofibers to be applied as cathode and as anode in these kind of the devices. In this thesis, it will be demonstrated that the nanostructured electrodes improve the efficiency devices thanks both to the low impedance and to the interaction with the microorganisms. The high micrometric porosity characteristics of the realized anodic material create the ideal habitat for the microorganism’s proliferation. Moreover, different solution for the cathode material have been developed using ceramic nanofibers, such as MnxOy nanofibers and carbon nanofibers, in order to improve the performance of the devices. The layer made of these nanofibers, in fact, catalyzes the oxygen reduction reaction if the oxygen is used as terminal electron acceptor in the devices; thus these catalysts can substitute the platinum layer, which is the most used today, granting a cheaper and eco friendlier material

Synthesis and Self-Assembly of Polymeric Hybrid Nanomaterials

The ability to construct functional polymeric hybrid nanomaterials is critically important for many applications. In this thesis I present the synthesis of amphiphilic polymers of various compositions including insulating coil-coil, semiconducting rod-coil, semiconducting brush-coil, and bioconjugated rod-coil polymers. The self-assembly of these polymers is presented along with methodologies for controlling the organization of nanomaterials and polymers towards the construction of functional hybrid materials with controllable structures and properties. In this thesis, an analysis of the conditions necessary to stabilize the cooperative self-assembly of nanoparticles and amphiphilic block copolymers into a unique cavity-like structure is presented. This work reveals the mechanism behind the formation of the structure and presents experimental and theoretical phase maps that show the conditions required to stabilize this structure for a range of nanoparticle sizes. These self-assembly guidelines provide an essential foundation for the generation of functional composites with predesigned structures and properties. A high-yield click chemistry synthesis of an amphiphilic conjugated block copolymer with systematic block lengths that self-assembles into well-defined nanofibers whose length can be effectively controlled by varying the relative block-lengths is also presented. Furthermore, superstructures of bundled and branched nanofibers with tunable shapes, lengths, and densities were fabricated through hierarchical self-assembly. This work demonstrates that complex superstructures of organic semiconductors can be fabricated via bottom-up self-assembly approach using preformed nanofibers as building blocks. The solution phase self-assembly of an amphiphilic conjugated brush copolymer into an elongated nanoribbon structure is also reported. The subtle effects of hydrogen bonding and pi-pi stacking interactions were investigated and found to be critical in the formation of this unusual structure which has not been reported for amphiphilic conjugated block copolymers and is important because it could offer insight into how internal packing structures affect the electronic properties of the polymer. The synthesis and self-assembly of a bio-conjugated rod-coil block copolymer into distinct nanostructures is also presented. These functional bio-conjugated polymers combine the optoelectronic properties of semiconducting polymers with the bio-recognition properties of DNA and is important because it offers a new approach to forming semiconducting nanostructures with controllable geometries by self-assembly and to interface with biological molecules

전기방사 공정을 통한 헬리컬 구조의 은나노 섬유의 제조

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 재료공학부(하이브리드 재료), 2020. 8. 유웅열.This study aimed to fabricate silver nanofibers using new process parameters of electrospinning and develop transparent and stretchable electrodes for stretchable electronics using them. A series of research was carried out to achieve goals as follows. A multi-physics model for the simulation of gas-assisted melt-electrospinning (GAME) process was developed to understand the roles of process parameters. By numerically calculating the stresses acting on the jet during a single-nozzle GAME process, the shear viscous stress was identified as the main factor of jet stretch. The jet stretch ratio increased sharply when shear viscous stress reached the level at which jet sharpening occurred, leading to stable jet formation. This stress was defined as the critical shear viscous stress to determine stable spinnability. In addition, a multi-nozzle GAME was simulated, proposing a spinnability diagram for stable spinning. A new process was designed to fabricate helical fibers. Here, the effect of solidification behavior of the jet on the formation of intrinsic curvature and on the final morphology of electrospun fibers was investigated. Fiber morphology during electrospinning was observed to dramatically change from straight to helical due to rapid solidification of the jet. Investigation of the resulting jet morphologies revealed that fiber structure changed from straight to helical as the vapor pressure increased. A similar effect was observed with conductive solutions prepared by adding large amounts of metal ion to the polymer solution. Simulations revealed that the jet near the nozzle tip was subject to a strong electrical field due to increased charge density. The thickness of the emerging fiber was rapidly reduced with fast and simultaneous solidification, resulting in helical nanofibers. A mechanism was suggested that can describe the formation of helical fibers. Transparent and stretchable electrodes (TSEs) was fabricated using electrospun silver nanofibers. Here, a composite comprising shape memory polymer–TSE (SMP–TSE) using crosslinked polycyclooctene as a substrate was fabricated, which showed wrinkle-free deformation and switchable optical transparency. Because of its considerable elongation without residual strain and the shape memory behavior of polycyclooctene, in-plane buckled nanofibers were formed effectively. Due to these in-plane buckled nanofibers, the electrode maintained its resistance during 3,000 cycles of a bending test and 900 cycles of a tensile test. Furthermore, SMP–TSE was able to electrically control its temperature, optical transparency, elastic modulus, and shape memory behavior. Finally, SMP–TSE was demonstrated for a smart electrode that could control its optical and mechanical properties. Keywords: Electrospinning, Numerical simulation, Process parameters, Silver nanofibers, Transparent and stretchable electrode Student number: 2014-22539본 연구의 목적은 전기방사 공정에서의 새로운 공정 변수들을 이용하여 은나노섬유를 제작하고 이를 활용하여 투명·신축 전극을 제작하는 것이다. 이를 위한 일련의 연구들이 다음의 순서로 진행되었다. Gas-assisted 용융 전기방사 공정에 대한 multi-physics 모델링을 개발하였으며 이를 통하여 공정 변수들의 역할을 파악하였다. 단일 노즐을 이용한 공정에서 젯의 표면에 인가되는 응력을 수치해석을 통하여 분석함으로써 젯의 인장에 있어 점성 전단 응력이 주요하게 작용함을 밝혀냈다. 젯은 점성 전단 응력이 특정 값에 도달하였을 때에 안정적으로 형성되었으며, 젯의 인장률 또한 급격히 증가하였다. 이때의 응력을 안정적인 방사성을 판단하는 임계 점성 전단 응력이라 정의 하였다. 단일 노즐 공정뿐만 아니라 멀티 노즐 공정을 모델링하였으며 이로부터 안정적인 방사성을 판단할 수 있는 방사성 다이어그램을 제시하였다. 다음으로는 섬유의 구조를 헬리컬 구조로 제작하는 공정을 디자인 하였다. 우선, 젯의 초기 곡률과 젯의 위치에 따른 고화가 섬유의 구조에 미치는 영향을 조사하였다. 전기 방사된 섬유의 구조는 용매의 증기압이 증가함에 따라 발생하는 빠른 고화로 인하여 직선형태에서 헬리컬 구조로 변화하였다. 이는 금속 이온이 과량으로 첨가된 전도성 용액에 대해서도 유사한 결과를 보였다. 이에 대한 시뮬레이션 결과는 전하 밀도의 증가가 강한 전기장을 발생시켰으며, 이로 인하여 젯의 급격한 인장 및 고화가 발생하였음을 보여주며, 그러한 이유로 헬리컬 구조가 형성되었음 나타냈다. 이를 이용하여 헬리컬 구조의 섬유가 형성되는 메커니즘을 제시하였다. 마지막으로 전기방사를 이용해 제작한 은나노섬유를 이용하여 투명·신축 전극을 제작하였다. 전극은 형상기억 고분자인 crosslinked polycyclooctene을 기판으로 활용하였다. 제작한 전극은 잔류 변형이 없고 투명도를 제어할 수 있는 특성을 보였다. 큰 인장에도 잔류 변형을 보이지 않는 형상기억고분자 기판의 특성으로 인해 면내 굽힘 구조의 은나노섬유가 효율적으로 제작되었다. 이러한 특성으로 제작한 전극은 3,000회의 굽힘 평가와 900회의 인장평가에도 전도성을 유지할 수 있었다. 또한 제작한 전극은 전기적 자극을 통하여 온도, 투명도, 강성 및 형상기억 특성을 제어할 수 있다는 특징을 보였다. 제작한 전극을 활용하여 광학적 그리고 기계적 특성을 제어할 수 있는 새로운 형태의 스마트 전극을 시연 하였다. 핵심어: 전기방사공정, 전산모사, 공정변수, 은나노섬유, 투명·신축 전극 학번: 2014-22539Chapter 1. Introduction 1 1.1. Electrospinning 1 1.1.1. Introduction of electrospinning 1 1.1.2. Types of electrospinning 3 1.1.3. Parameters in electrospinning 6 1.1.4. Structures of electrospun nanofibers 16 1.1.5. Application of electrospun nanofibers 26 1.1.6. Limitation and perspective of electrospinning 44 1.2. Research objectives 47 Chapter 2. Numerical simulation of gas-assisted melt electrospinning 50 2.1. Needs for modeling of gas-assisted melt electrospinning 50 2.2. Methods 53 2.2.1. Gas-assisted melt-electrospinning process 53 2.2.2. Numerical simulation of single-nozzle GAME process 56 2.2.3. Calculation of electric field in multi-nozzle configuration 60 2.2.4. Numerical simulation of multi-nozzle GAME process 61 2.3. Results and discussion 62 2.3.1. Simulation of single-nozzle GAME process 62 2.3.2. Simulation of multi-nozzle GAME process 73 2.4. Summary 81 Chapter 3. Fabrication of inherently helical structure nanofibers 83 3.1. Needs for fabrication of helical nanofibers 83 3.2. Experimental 85 3.2.1. Preparation of dielectric solution for helical nanofibers 84 3.2.2. Preparation of conductive solution for helical nanofibers 86 3.2.3. Electrospinning and spinneret geometry 86 3.2.4. Characterization of Electrospun Fibers 87 3.3. Results and discussion 88 3.3.1. Effect of solvent vapor pressure on structure 88 3.3.2. Effects of solidification on structure 94 3.3.3. Numerical simulations of jet near nozzle 99 3.3.4. Further enhanced helical structrues 105 3.4. Summary 111 Chapter 4. Fabrication of a stretchable, wrinkle-free electrode with switchable transparency 113 4.1. Transparent and stretchable electrode 113 4.2. Experimental 116 4.2.1. Materials 116 4.2.2. Preparation of shape memory polymer substrate 117 4.2.3. Fabrication of free-standing silver nanofiber 117 4.2.4. Characterization of SMP–TSE 118 4.3. Results and discussion 119 4.3.1. Fabrication of free-standing silver nanofibers 119 4.3.2. Optoelectrical properties of silver nanofibers 128 4.3.3. Shape memory substrate 129 4.3.4. Shape memory polymer–transparent and stretchable electrode 137 4.4. Summary 143 Chapter 5. Conclusions 145 Chapter 6. Appendix 147 Reference 161 Korean abstract 189Docto

Prospects of Emerging Engineered oxide nanomaterials and their Applications

This review article mainly focused on the recent progress on the synthesis and characterization of emerging artificially engineered nanostructures of oxide materials as well as their potential applications. A fundamental understanding about the state-of-the-art of the synthesis for different size, shape and morphology, which can be tuned to the desired properties of oxide nanomaterials have discussed in details in this review. The present review covers the a wide range of artificially engineered oxide nanomaterials such as cadmium-, cupric-, nickel-, magnesium-, zinc-, titanium-, tin-, aluminium-, and vanadium-oxides and their useful applications in sensors, optical displays, nanofluids and defence

Protein and Polysaccharide-Based Fiber Materials Generated from Ionic Liquids: A Review.

Natural biomacromolecules such as structural proteins and polysaccharides are composed of the basic building blocks of life: amino acids and carbohydrates. Understanding their molecular structure, self-assembly and interaction in solvents such as ionic liquids (ILs) is critical for unleashing a flora of new materials, revolutionizing the way we fabricate multi-structural and multi-functional systems with tunable physicochemical properties. Ionic liquids are superior to organic solvents because they do not produce unwanted by-products and are considered green substitutes because of their reusability. In addition, they will significantly improve the miscibility of biopolymers with other materials while maintaining the mechanical properties of the biopolymer in the final product. Understanding and controlling the physicochemical properties of biopolymers in ionic liquids matrices will be crucial for progress leading to the ability to fabricate robust multi-level structural 1D fiber materials. It will also help to predict the relationship between fiber conformation and protein secondary structures or carbohydrate crystallinity, thus creating potential applications for cell growth signaling, ionic conductivity, liquid diffusion and thermal conductivity, and several applications in biomedicine and environmental science. This will also enable the regeneration of biopolymer composite fiber materials with useful functionalities and customizable options critical for additive manufacturing. The specific capabilities of these fiber materials have been shown to vary based on their fabrication methods including electrospinning and post-treatments. This review serves to provide basic knowledge of these commonly utilized protein and polysaccharide biopolymers and their fiber fabrication methods from various ionic liquids, as well as the effect of post-treatments on these fiber materials and their applications in biomedical and pharmaceutical research, wound healing, environmental filters and sustainable and green chemistry research

Multilayer Thin Films

This book, "Multilayer Thin Films-Versatile Applications for Materials Engineering", includes thirteen chapters related to the preparations, characterizations, and applications in the modern research of materials engineering. The evaluation of nanomaterials in the form of different shapes, sizes, and volumes needed for utilization in different kinds of gadgets and devices. Since the recently developed two-dimensional carbon materials are proving to be immensely important for new configurations in the miniature scale in the modern technology, it is imperative to innovate various atomic and molecular arrangements for the modifications of structural properties. Of late, graphene and graphene-related derivatives have been proven as the most versatile two-dimensional nanomaterials with superb mechanical, electrical, electronic, optical, and magnetic properties. To understand the in-depth technology, an effort has been made to explain the basics of nano dimensional materials. The importance of nano particles in various aspects of nano technology is clearly indicated. There is more than one chapter describing the use of nanomaterials as sensors. In this volume, an effort has been made to clarify the use of such materials from non-conductor to highly conducting species. It is expected that this book will be useful to the postgraduate and research students as this is a multidisciplinary subject