Colloidal Crystal: Emergence of Long Range Order from Colloidal Fluid
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2 a Primer on Polymer Colloids: Structure, Synthesis and Colloidal Stability
A. Al Shboul, F. Pierre, and J. P. Claverie 2 A primer on polymer colloids: structure, synthesis and colloidal stability 2.1 Introduction A colloid is a dispersion of very fine objects in a fluid [1]. These objects can be solids, liquids or gas, and the corresponding colloidal dispersion is then referred to as sus- pension, emulsion or foam. Colloids possess unique characteristics. For example, as their size is smaller than the wavelength of light, they scatter light. They also offer a large interfacial surface area, meaning that interfacial phenomena are of paramount importance in these dispersions. The weight of each dispersed particle being small, gravity and buoyancy forces are not sufficient to counteract the thermal random mo- tion of the particle, named Brownian motion (in tribute to the 19th century botanist Robert Brown who first characterized it). The particles do not remain in a dispersed state indefinitely: they will sooner or later aggregate (phase separation). Thus, thecol- loidal state is in general metastable and colloidal stability is one of the key features to take into account when working with colloids. Among all colloids, the polymer colloid family is one of the most widely inves- tigated [2]. Polymer colloids are used for a large number of applications, ranging from coatings, adhesives, inks, impact modifiers, drug-delivery vehicles, etc. The particles range in size from about 10 nm to 1 000 nm (1 μm) in diameter. They are usually spherical, but numerous other shapes have been observed. Polymer colloids are not uncommon in nature. For example, natural rubber latex, the secretion of the Hevea brasiliensis tree, is in fact a dispersion of polyisoprene nanoparticles in wa- ter. -
4. Fabrication of Polymer-Immobilized Colloidal Crystal Films (851Kb)
R&D Review of Toyota CRDL, Vol.45 No.1 (2014) 17- 22 17 Special Feature: Applied Nanoscale Morphology Research Report Fabrication of Polymer-immobilized Colloidal Crystal Films Masahiko Ishii Report received on Feb. 28, 2014 A fabrication method for polymer-immobilized colloidal crystal fi lms using conventional spray coating has been developed for application of the fi lms as practical colored materials. By controlling both the viscosity of the silica sphere-acrylic monomer dispersions and the wettability of the substrates, colloidal crystalline fi lms with brilliant iridescent colors were successfully obtained by spray coating and UV curing. The color could be controlled by adjusting both the sphere concentration and diameter. Scanning electron microscopy was applied to study the crystal structure of the coated fi lms, and revealed that the fi lms are composed of highly oriented face-centered-cubic grains with (111) planes parallel to the substrate surface. A method for utilizing the colloidal crystal fi lms as pigments was also proposed. Flakes obtained by crushing the colloidal crystal coated fi lms were added to a commercial clear paint and coated on a substrate. The coated fi lms exhibited iridescent colors that varies with viewing angle. Colloidal Crystal, Self-assembly, Silica, Polymeric Material, Spray Coating 1. Introduction arrays of monodispersed sub-micrometer sized spheres. They exhibit iridescent colors due to Bragg diffraction Jewels such as diamonds and rubies are beautiful, of visible light when they have a periodicity on the attracting the attention of people worldwide. Most of scale of the wavelength of the light. The most common these are natural minerals with crystalline structures. -
Plasmofluidic Single-Molecule Surface-Enhanced Raman
ARTICLE Received 24 Feb 2014 | Accepted 9 Jun 2014 | Published 7 Jul 2014 DOI: 10.1038/ncomms5357 Plasmofluidic single-molecule surface-enhanced Raman scattering from dynamic assembly of plasmonic nanoparticles Partha Pratim Patra1, Rohit Chikkaraddy1, Ravi P.N. Tripathi1, Arindam Dasgupta1 & G.V. Pavan Kumar1 Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal–fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal–fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms. 1 Photonics and Optical Nanoscopy Laboratory, h-cross, Indian Institute of Science Education and Research, Pune 411008, India. Correspondence and requests for materials should be addressed to G.V.P.K. (email: [email protected]). NATURE COMMUNICATIONS | 5:4357 | DOI: 10.1038/ncomms5357 | www.nature.com/naturecommunications 1 & 2014 Macmillan Publishers Limited. All rights reserved. -
Generation and Stability of Size-Adjustable Bulk Nanobubbles
www.nature.com/scientificreports OPEN Generation and Stability of Size-Adjustable Bulk Nanobubbles Based on Periodic Pressure Received: 10 September 2018 Accepted: 18 December 2018 Change Published: xx xx xxxx Qiaozhi Wang, Hui Zhao, Na Qi, Yan Qin, Xuejie Zhang & Ying Li Recently, bulk nanobubbles have attracted intensive attention due to the unique physicochemical properties and important potential applications in various felds. In this study, periodic pressure change was introduced to generate bulk nanobubbles. N2 nanobubbles with bimodal distribution and excellent stabilization were fabricated in nitrogen-saturated water solution. O2 and CO2 nanobubbles have also been created using this method and both have good stability. The infuence of the action time of periodic pressure change on the generated N2 nanobubbles size was studied. It was interestingly found that, the size of the formed nanobubbles decreases with the increase of action time under constant frequency, which could be explained by the diference in the shrinkage and growth rate under diferent pressure conditions, thereby size-adjustable nanobubbles can be formed by regulating operating time. This study might provide valuable methodology for further investigations about properties and performances of bulk nanobubbles. Nanobubbles are gaseous domains which could be found at the solid/liquid interface or in solution, known as surface nanobubbles (SNBs)1,2 and bulk nanobubbles (BNBs)3, respectively. For BNBs, generally recognized as spherical bubbles with the diameter of less than 1μm surrounded by liquid, though it has been observed frstly in 19814, the existence of long-lived BNBs is still a controversial subject as it is contrary to the classical theory5,6. -
The Development of the Science of Superconductivity and Superfluidity
Universal Journal of Physics and Application 1(4): 392-407, 2013 DOI: 10.13189/ujpa.2013.010405 http://www.hrpub.org Superconductivity and Superfluidity-Part I: The development of the science of superconductivity and superfluidity in the 20th century Boris V.Vasiliev ∗Corresponding Author: [email protected] Copyright ⃝c 2013 Horizon Research Publishing All rights reserved. Abstract Currently there is a common belief that the explanation of superconductivity phenomenon lies in understanding the mechanism of the formation of electron pairs. Paired electrons, however, cannot form a super- conducting condensate spontaneously. These paired electrons perform disorderly zero-point oscillations and there are no force of attraction in their ensemble. In order to create a unified ensemble of particles, the pairs must order their zero-point fluctuations so that an attraction between the particles appears. As a result of this ordering of zero-point oscillations in the electron gas, superconductivity arises. This model of condensation of zero-point oscillations creates the possibility of being able to obtain estimates for the critical parameters of elementary super- conductors, which are in satisfactory agreement with the measured data. On the another hand, the phenomenon of superfluidity in He-4 and He-3 can be similarly explained, due to the ordering of zero-point fluctuations. It is therefore established that both related phenomena are based on the same physical mechanism. Keywords superconductivity superfluidity zero-point oscillations 1 Introduction 1.1 Superconductivity and public Superconductivity is a beautiful and unique natural phenomenon that was discovered in the early 20th century. Its unique nature comes from the fact that superconductivity is the result of quantum laws that act on a macroscopic ensemble of particles as a whole. -
Colloidal Crystals with a 3D Photonic Bandgap
Part I General Introduction I.1 Photonic Crystals A photonic crystal (PC) is a regularly structured material, with feature sizes on the order of a wavelength (or smaller), that exhibits strong interaction with light.1-3 The main concept behind photonic crystals is the formation of a 'photonic band gap'. For a certain range of frequencies, electromagnetic waves are diffracted by the periodic modulations in the dielectric constant of the PC forming (directional) stop bands. If the stop bands are wide enough to overlap for both polarization states along all crystal directions, the material is said to possess a complete photonic band gap (CPBG). In such a crystal, propagation of electromagnetic waves with frequencies lying within the gap is forbidden irrespective of their direction of propagation and polarization.1,2 This leads to the possibility to control the spontaneous emission of light. For example, an excited atom embedded in a PC will not be able to make a transition to a lower energy state as readily if the frequency of the emitted photon lies within the band gap, hence increasing the lifetime of the excited state.1,2 Photonic crystals with a (directional) stop gap can also have a significant effect on the spontaneous-emission rate.4 If a defect or mistake in the periodicity is introduced in the otherwise perfect crystal, localized photonic states in the gap will be created. A point defect could act like a microcavity, a line defect like a wave-guide, and a planar defect like a planar wave-guide. By introducing defects, light can be localized or guided along the defects modes.1,2 1 2 a b Figure I.1–1 Scanning electron micrograph (SEM) of a face-centered-cubic (fcc) colloidal crystal of closed-packed silica spheres (R = 110 nm). -
Sounds of a Supersolid A
NEWS & VIEWS RESEARCH hypothesis came from extensive population humans, implying possible mosquito exposure long-distance spread of insecticide-resistant time-series analysis from that earlier study5, to malaria parasites and the potential to spread mosquitoes, worsening an already dire situ- which showed beyond reasonable doubt that infection over great distances. ation, given the current spread of insecticide a mosquito vector species called Anopheles However, the authors failed to detect resistance in mosquito populations. This would coluzzii persists locally in the dry season in parasite infections in their aerially sampled be a matter of great concern because insecticides as-yet-undiscovered places. However, the malaria vectors, a result that they assert is to be are the best means of malaria control currently data were not consistent with this outcome for expected given the small sample size and the low available8. However, long-distance migration other malaria vectors in the study area — the parasite-infection rates typical of populations of could facilitate the desirable spread of mosqui- species Anopheles gambiae and Anopheles ara- malaria vectors. A problem with this argument toes for gene-based methods of malaria-vector biensis — leaving wind-powered long-distance is that the typical infection rates they mention control. One thing is certain, Huestis and col- migration as the only remaining possibility to are based on one specific mosquito body part leagues have permanently transformed our explain the data5. (salivary glands), rather than the unknown but understanding of African malaria vectors and Both modelling6 and genetic studies7 undoubtedly much higher infection rates that what it will take to conquer malaria. -
Lecture Notes for Quantum Matter
Lecture Notes for Quantum Matter MMathPhys c Professor Steven H. Simon Oxford University July 24, 2019 Contents 1 What we will study 1 1.1 Bose Superfluids (BECs, Superfluid He, Superconductors) . .1 1.2 Theory of Fermi Liquids . .2 1.3 BCS theory of superconductivity . .2 1.4 Special topics . .2 2 Introduction to Superfluids 3 2.1 Some History and Basics of Superfluid Phenomena . .3 2.2 Landau and the Two Fluid Model . .6 2.2.1 More History and a bit of Physics . .6 2.2.2 Landau's Two Fluid Model . .7 2.2.3 More Physical Effects and Their Two Fluid Pictures . .9 2.2.4 Second Sound . 12 2.2.5 Big Questions Remaining . 13 2.3 Curl Free Constraint: Introducing the Superfluid Order Parameter . 14 2.3.1 Vorticity Quantization . 15 2.4 Landau Criterion for Superflow . 17 2.5 Superfluid Density . 20 2.5.1 The Andronikoshvili Experiment . 20 2.5.2 Landau's Calculation of Superfluid Density . 22 3 Charged Superfluid ≈ Superconductor 25 3.1 London Theory . 25 3.1.1 Meissner-Ochsenfeld Effect . 27 3 3.1.2 Quantum Input and Superfluid Order Parameter . 29 3.1.3 Superconducting Vortices . 30 3.1.4 Type I and Type II superconductors . 32 3.1.5 How big is Hc ............................... 33 4 Microscopic Theory of Bosons 37 4.1 Mathematical Preliminaries . 37 4.1.1 Second quantization . 37 4.1.2 Coherent States . 38 4.1.3 Multiple orbitals . 40 4.2 BECs and the Gross-Pitaevskii Equation . 41 4.2.1 Noninteracting BECs as Coherent States . -
Review Article Importance of Molecular Interactions in Colloidal Dispersions
Hindawi Publishing Corporation Advances in Condensed Matter Physics Volume 2015, Article ID 683716, 8 pages http://dx.doi.org/10.1155/2015/683716 Review Article Importance of Molecular Interactions in Colloidal Dispersions R. López-Esparza,1,2 M. A. Balderas Altamirano,1 E. Pérez,1 and A. Gama Goicochea1,3 1 Instituto de F´ısica, Universidad Autonoma´ de San Luis Potos´ı, 78290 San Luis Potos´ı, SLP, Mexico 2Departamento de F´ısica, Universidad de Sonora, 83000 Hermosillo, SON, Mexico 3Innovacion´ y Desarrollo en Materiales Avanzados A. C., Grupo Polynnova, 78211 San Luis Potos´ı, SLP, Mexico Correspondence should be addressed to A. Gama Goicochea; [email protected] Received 21 May 2015; Accepted 2 August 2015 Academic Editor: Jan A. Jung Copyright © 2015 R. Lopez-Esparza´ et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We review briefly the concept of colloidal dispersions, their general properties, and some of their most important applications, as well as the basic molecular interactions that give rise to their properties in equilibrium. Similarly, we revisit Brownian motion and hydrodynamic interactions associated with the concept of viscosity of colloidal dispersion. It is argued that the use of modern research tools, such as computer simulations, allows one to predict accurately some macroscopically measurable properties by solving relatively simple models of molecular interactions for a large number of particles. Lastly, as a case study, we report the prediction of rheological properties of polymer brushes using state-of-the-art, coarse-grained computer simulations, which are in excellent agreement with experiments. -
Universality in Spectral Condensation Induja Pavithran1, Vishnu R
www.nature.com/scientificreports OPEN Universality in spectral condensation Induja Pavithran1, Vishnu R. Unni2*, Alan J. Varghese3, D. Premraj3, R. I. Sujith3,4*, C. Vijayan1, Abhishek Saha2, Norbert Marwan4 & Jürgen Kurths4,5,6 Self-organization is the spontaneous formation of spatial, temporal, or spatiotemporal patterns in complex systems far from equilibrium. During such self-organization, energy distributed in a broadband of frequencies gets condensed into a dominant mode, analogous to a condensation phenomenon. We call this phenomenon spectral condensation and study its occurrence in fuid mechanical, optical and electronic systems. We defne a set of spectral measures to quantify this condensation spanning several dynamical systems. Further, we uncover an inverse power law behaviour of spectral measures with the power corresponding to the dominant peak in the power spectrum in all the aforementioned systems. During self-organization, an ordered pattern emerges from an initially disordered state. In dynamical systems, a pattern can be any regularly repeating arrangements in space, time or both1. For example, a laser emits random wave tracks like a lamp until the critical pump power, above which the laser emits light as a single coherent wave track with high-intensity2. A macroscopic change is observed in the laser system as a long-range pattern emerges in time. Another example is the Rayleigh–Bénard system. For lower temperature gradients, the fuid parcels move randomly. As the temperature gradient is increased, a rolling motion sets in and the fuid parcels behave coherently to form spatially extended patterns. Te initial random pattern can be regarded as a superposition of a variety of oscillatory modes and eventually some oscillatory modes dominate, resulting in the emergence of a spatio-temporal pattern3,4. -
Surface Plasmon Resonance Study of the Purple Gold
SURFACE PLASMON RESONANCE STUDY OF THE PURPLE GOLD (AuAl2) INTERMETALLIC, pH-RESPONSIVE FLUORESCENCE GOLD NANOPARTICLES, AND GOLD NANOSPHERE ASSEMBLY Panupon Samaimongkol Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Physics Hans D. Robinson, Chair Giti Khodaparast Chenggang Tao Webster Santos June 22, 2018 Blacksburg, Virginia Keywords: Surface plasmons (SPs), Localized surface plasmon resonances (LSPRs), Kretschmann configuration, Surface plasmon-enhanced fluorescence (PEF) spectroscopy, Self-Assembly, Nanoparticles Copyright 2018, Panupon Samaimongkol i SURFACE PLASMON RESONANCE STUDY OF THE PURPLE GOLD (AuAl2) INTERMETALLIC, pH-RESPONSIVE FLUORESCENCE GOLD NANOPARTICLES, AND GOLD NANOSPHERE ASSEMBLY Panupon Samaimongkol ABSTRACT (academic) In this dissertation, I have verified that the striking purple color of the intermetallic compound AuAl2, also known as purple gold, originates from surface plasmons (SPs). This contrasts to a previous assumption that this color is due to an interband absorption transition. The existence of SPs was demonstrated by launching them in thin AuAl2 films in the Kretschmann configuration, which enables us to measure the SP dispersion relation. I observed that the SP energy in thin films of purple gold is around 2.1 eV, comparable to previous work on the dielectric function of this material. Furthermore, SP sensing using AuAl2 also shows the ability to measure the change in the refractive index of standard sucrose solution. AuAl2 in nanoparticle form is also discussed in terms of plasmonic applications, where Mie scattering theory predicts that the particle bears nearly uniform absorption over the entire visible spectrum with an order magnitude higher absorption than efficient light-absorbing carbonaceous particle also known a carbon black. -
Polymer Colloid Science
Polymer Colloid Science Jung-Hyun Kim Ph. D. Nanosphere Process & Technology Lab. Department of Chemical Engineering, Yonsei University National Research Laboratory Project the financial support of the Korea Institute of S&T Evaluation and Planning (KISTEP) made in the program year of 1999 기능성 초미립자 공정연구실 Colloidal Aspects 기능성 초미립자 공정연구실 ♣ What is a polymer colloids ? . Small polymer particles suspended in a continuous media (usually water) . EXAMPLES - Latex paints - Natural plant fluids such as natural rubber latex - Water-based adhesives - Non-aqueous dispersions . COLLOIDS - The world of forgotten dimensions - Larger than molecules but too small to be seen in an optical microscope 기능성 초미립자 공정연구실 ♣ What does the term “stability/coagulation imply? . There is no change in the number of particles with time. A system is said to be colloidally unstable if collisions lead to the formation of aggregates; such a process is called coagulation or flocculation. ♣ Two ways to prevent particles from forming aggregates with one another during their colliding 1) Electrostatic stabilization by charged group on the particle surface - Origin of the charged group - initiator fragment (COOH, OSO3 , NH4, OH, etc) ionic surfactant (cationic or anionic) ionic co-monomer (AA, MAA, etc) 2) Steric stabilization by an adsorbed layer of some substance 3) Solvation stabilization 기능성 초미립자 공정연구실 기능성 초미립자 공정연구실 Stabilization Mechanism Electrostatic stabilization - Electrostatic stabilization Balancing the charge on the particle surface by the charges on small ions