Soft matter
Encyclopedia
Soft matter is a subfield of condensed matter
comprising a variety of physical states that are easily deformed by thermal stresses or thermal fluctuations. They include liquid
s, colloids, polymers, foam
s, gels, granular material
s, and a number of biological materials. These materials share an important common feature in that predominant physical behaviors occur at an energy
scale comparable with room temperature
thermal energy
. At these temperatures, quantum
aspects are generally unimportant.
Pierre-Gilles de Gennes
, who has been called the "founding father of soft matter," received the Nobel Prize in physics
in 1991 for discovering that the order parameter from simple thermodynamic
systems can be applied to the more complex cases found in soft matter, in particular, to the behaviors of liquid crystal
s and polymers.
into mesoscopic physical structures that are much larger than the microscopic scale (the arrangement of atom
s and molecule
s), and yet are much smaller than the macroscopic (overall) scale of the material. The properties and interactions of these mesoscopic structures may determine the macroscopic behavior of the material. For example, the turbulent
vortices
that naturally occur within a flowing liquid
are much smaller than the overall quantity of liquid and yet much larger than its individual molecules, and the emergence of these vortices control the overall flowing behavior of the material. Also, the bubbles that comprise a foam
are mesoscopic because they individually consist of a vast number of molecules, and yet the foam itself consists of a great number of these bubbles, and the overall mechanical stiffness of the foam emerges from the combined interactions of the bubbles. By way of contrast, in hard condensed matter physics
it is often possible to predict the overall behavior of a material because the molecules are organized into a crystalline lattice with no changes in the pattern at any mesoscopic scale.
and enthalpic
contributions to the free energy
. These properties lead to large thermal fluctuations
, a wide variety of forms, sensitivity of equilibrium structures to external conditions, macroscopic softness
, and metastable states.
, generalized elasticity, and many fluctuating degrees of freedom has re-invigorated classical fields of physics
such as fluid
s (now generalized to non-Newtonian
and structured media) and elasticity (membranes, filaments, and anisotropic networks are all important and have common aspects). Soft condensed matter is directly related to studies in biophysics. One possible roadblock to the development of biophysics as an established field is that soft condensed matter may be diverging into two distinct directions: a physical chemistry approach and a complex systems approach.
Condensed Matter
Condensed matter may refer to several things*Condensed matter physics, the study of the physical properties of condensed phases of matter*European Physical Journal B: Condensed Matter and Complex Systems, a scientific journal published by EDP sciences...
comprising a variety of physical states that are easily deformed by thermal stresses or thermal fluctuations. They include liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
s, colloids, polymers, foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
s, gels, granular material
Granular material
A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact . The constituents that compose granular material must be large enough such that they are not subject to thermal motion fluctuations...
s, and a number of biological materials. These materials share an important common feature in that predominant physical behaviors occur at an energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
scale comparable with room temperature
Room temperature
-Comfort levels:The American Society of Heating, Refrigerating and Air-Conditioning Engineers has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ratio per...
thermal energy
Thermal energy
Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system's temperature....
. At these temperatures, quantum
Quantum
In physics, a quantum is the minimum amount of any physical entity involved in an interaction. Behind this, one finds the fundamental notion that a physical property may be "quantized," referred to as "the hypothesis of quantization". This means that the magnitude can take on only certain discrete...
aspects are generally unimportant.
Pierre-Gilles de Gennes
Pierre-Gilles de Gennes
Pierre-Gilles de Gennes was a French physicist and the Nobel Prize laureate in physics in 1991.-Biography:...
, who has been called the "founding father of soft matter," received the Nobel Prize in physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
in 1991 for discovering that the order parameter from simple thermodynamic
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
systems can be applied to the more complex cases found in soft matter, in particular, to the behaviors of liquid crystal
Liquid crystal
Liquid crystals are a state of matter that have properties between those of a conventional liquid and those of a solid crystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be...
s and polymers.
Distinctive physics
Interesting behaviors arise from soft matter in ways that cannot be predicted, or are difficult to predict, directly from its atomic or molecular consituents. This is often because soft matter self-organizesSelf-organization
Self-organization is the process where a structure or pattern appears in a system without a central authority or external element imposing it through planning...
into mesoscopic physical structures that are much larger than the microscopic scale (the arrangement of atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s and molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s), and yet are much smaller than the macroscopic (overall) scale of the material. The properties and interactions of these mesoscopic structures may determine the macroscopic behavior of the material. For example, the turbulent
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
vortices
Vortex
A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...
that naturally occur within a flowing liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
are much smaller than the overall quantity of liquid and yet much larger than its individual molecules, and the emergence of these vortices control the overall flowing behavior of the material. Also, the bubbles that comprise a foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
are mesoscopic because they individually consist of a vast number of molecules, and yet the foam itself consists of a great number of these bubbles, and the overall mechanical stiffness of the foam emerges from the combined interactions of the bubbles. By way of contrast, in hard condensed matter physics
Condensed matter physics
Condensed matter physics deals with the physical properties of condensed phases of matter. These properties appear when a number of atoms at the supramolecular and macromolecular scale interact strongly and adhere to each other or are otherwise highly concentrated in a system. The most familiar...
it is often possible to predict the overall behavior of a material because the molecules are organized into a crystalline lattice with no changes in the pattern at any mesoscopic scale.
Applications
Soft materials are important in a wide range of technological applications. They may appear as structural and packaging materials, foams and adhesives, detergents and cosmetics, paints, food additives, lubricants and fuel additives, rubber in tires, etc. In addition, a number of biological materials (blood, muscle, milk, yogurt, jello) are classifiable as soft matter. Liquid crystals, another category of soft matter, exhibit a responsivity to electric fields that make them very important as materials in display devices (LCDs). In spite of the various forms of these materials, many of their properties have common physicochemical origins, such as a large number of internal degrees of freedom, weak interactions between structural elements, and a delicate balance between entropicEntropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
and enthalpic
Enthalpy
Enthalpy is a measure of the total energy of a thermodynamic system. It includes the internal energy, which is the energy required to create a system, and the amount of energy required to make room for it by displacing its environment and establishing its volume and pressure.Enthalpy is a...
contributions to the free energy
Helmholtz free energy
In thermodynamics, the Helmholtz free energy is a thermodynamic potential that measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature and volume...
. These properties lead to large thermal fluctuations
Thermal fluctuations
In statistical mechanics, thermal fluctuations are random deviations of a system from its equilibrium. All thermal fluctuations become larger and more frequent as the temperature increases, and likewise they disappear altogether as temperature approaches absolute zero.Thermal fluctuations are a...
, a wide variety of forms, sensitivity of equilibrium structures to external conditions, macroscopic softness
Softness
Softness may refer to:* The opposite of one of the many types of hardness.* A texture which is the opposite of roughness....
, and metastable states.
Research
The realization that soft matter contains innumerable examples of symmetry breakingSymmetry breaking
Symmetry breaking in physics describes a phenomenon where small fluctuations acting on a system which is crossing a critical point decide the system's fate, by determining which branch of a bifurcation is taken. To an outside observer unaware of the fluctuations , the choice will appear arbitrary...
, generalized elasticity, and many fluctuating degrees of freedom has re-invigorated classical fields of physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
such as fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
s (now generalized to non-Newtonian
Newtonian fluid
A Newtonian fluid is a fluid whose stress versus strain rate curve is linear and passes through the origin. The constant of proportionality is known as the viscosity.-Definition:...
and structured media) and elasticity (membranes, filaments, and anisotropic networks are all important and have common aspects). Soft condensed matter is directly related to studies in biophysics. One possible roadblock to the development of biophysics as an established field is that soft condensed matter may be diverging into two distinct directions: a physical chemistry approach and a complex systems approach.
Multi-Investigator Groups and Centers
- http://www.dcf.ds.mpg.de/Dynamics of Complex Fluids department at the Max Planck Institute for Dynamics and Self-OrganizationMax Planck Institute for Dynamics and Self-OrganizationThe Max Planck Institute for Dynamics and Self-organisation in Göttingen, Germany, is a research institute for investigations of complex non-equilibrium systems, particularly in physics and biology....
, Göttingen, Germany] - Soft Matter Group at van der Waals-Zeeman Institute, University of Amsterdam, NL
- Soft Matter Chemistry Group, University of Leiden, NL
- Freiburg Institute for Advanced Studies (FRIAS), School of Soft Matter Research, University of Freiburg, D
- http://csmr.as.nyu.edu/page/homeCenter for Soft Matter Research New York UniversityNew York UniversityNew York University is a private, nonsectarian research university based in New York City. NYU's main campus is situated in the Greenwich Village section of Manhattan...
, US] - Physics of Soft and Partially Ordered Matter Faculty of Mathematics and Physics University of LjubljanaUniversity of LjubljanaThe University of Ljubljana is the oldest and largest university in Slovenia. With 64,000 enrolled graduate and postgraduate students, it is among the largest universities in Europe.-Beginnings:...
, SLOSloveniaSlovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of... - Soft Matter and Molecular Biophysics Group, Department of Applied Physics, University of Santiago de Compostela, Spain
- Soft Matter Team, Laboratoire Charles Coulomb, CNRS and University Montpellier 2, Montpellier, France
Single-Investigator Groups
- Dr. Martin O. Steinhauser's Research Group 'Shock Waves in Soft Biological Matter' at the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI, Freiburg, https://www.mmm-tools.de, Germany]
- Prof. Peter Schurtenberger's Group, Adolphe Merkle Institute, CH
- http://azsoftmatter.wordpress.comProf A V Zvelindovsky's Computational Physics Group, University of Central LancashireUniversity of Central LancashireThe University of Central Lancashire is a university based in Preston, Lancashire, England.The university has its roots in The Institution For The Diffusion Of Useful Knowledge which was founded in 1828. In 1992 it was granted University status by the Privy Council...
, UK] - http://www.seas.harvard.edu/projects/weitzlab/Soft Matter Physics Group (Weitzlab), Harvard UniversityHarvard UniversityHarvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
, US] - http://nagelgroup.uchicago.edu/Nagel-Group/LabHome.htmlNagel Group, University of ChicagoUniversity of ChicagoThe University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
, US] - Dr. Ramón Castañeda-Priego's Group, Mexico
- Rolando Castillo's Group at UNAM, Mexico
- Theory and Computation of Advanced Materials, Stephan Baeurle's Group at Regensburg University, Germany
- http://physics.nyu.edu/grierlab/David Grier's Group, New York UniversityNew York UniversityNew York University is a private, nonsectarian research university based in New York City. NYU's main campus is situated in the Greenwich Village section of Manhattan...
, US] - http://www.physics.emory.edu/~weeks/labEric Weeks' Group, Emory UniversityEmory UniversityEmory University is a private research university in metropolitan Atlanta, located in the Druid Hills section of unincorporated DeKalb County, Georgia, United States. The university was founded as Emory College in 1836 in Oxford, Georgia by a small group of Methodists and was named in honor of...
, US] - Computational Soft Matter Science, Prof. Florian Müller-Plathe's Research Group
- Polymer Physics and Complex Fluids Group, Yeng-Long Chen's Research Group at Academia Sinica
- http://www.physics.mun.ca/~anandSoft Matter Lab, Memorial University of NewfoundlandMemorial University of NewfoundlandMemorial University of Newfoundland, is a comprehensive university located primarily in St...
, Canada] - http://www.che.ttu.edu/McKennaGrp/Polymer and Condensed Matter Physics Group, Greg McKenna's Labs, Texas Tech UniversityTexas Tech UniversityTexas Tech University, often referred to as Texas Tech or TTU, is a public research university in Lubbock, Texas, United States. Established on February 10, 1923, and originally known as Texas Technological College, it is the leading institution of the Texas Tech University System and has the...
, US] - Prof. Linda Hirst's soft matter physics group, University of California, Merced, US
Journals
- Soft MatterSoft Matter (journal)Soft Matter is a peer-reviewed scientific journal publishing original research and review articles on the generic science underpinning the properties and applications of soft matter...
- Soft Materials
- MacromoleculesMacromolecules (journal)Macromolecules is a peer-reviewed scientific journal that has been published since 1968 by the American Chemical Society. Macromolecules is currently indexed in: Scopus, EBSCOhost, PubMed, Ovid, Web of Science, and SwetsWise. The editor in chief is Timothy P. Lodge....
- LangmuirLangmuir (journal)Langmuir is a peer-reviewed scientific journal, published since 1985 by the American Chemical Society. It publishes research in the areas of surface chemistry and colloid chemistry...
- Macromolecular Theory and Simulation
- Physical Review EPhysical Review LettersPhysical Review Letters , established in 1958, is a peer reviewed, scientific journal that is published 52 times per year by the American Physical Society...
- Journal of Physical Chemistry BJournal of Physical Chemistry BThe Journal of Physical Chemistry B is a peer-reviewed scientific journal that covers research on several fields of material chemistry as well as statistical mechanics, thermodynamics, and biophysical chemistry...
- Journal of Chemical PhysicsJournal of Chemical PhysicsThe Journal of Chemical Physics is a scientific journal that publishes research papers on all areas of chemical physics. Two volumes, each of 24 issues, are published per year. It is published by the American Institute of Physics. The editors have been:...
- European Physical Journal EEuropean Physical Journal EThe European Physical Journal E: Soft Matter and Biological Physics is a scientific journal focusing on the physics of soft matter and biophysics. It publishes papers describing advances in the understanding of physical aspects of soft matter and biological systems...
- Nano LettersNano LettersNano Letters is a monthly, peer-reviewed, scientific journal, published by the American Chemical Society. It was first published in January 2001. The two Co-Editors-in-Chief are A. Paul Alivisatos and Charles M. Lieber...
Examples of soft matter
- ColloidColloidA colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...
s - Polymers
- Liquid crystalLiquid crystalLiquid crystals are a state of matter that have properties between those of a conventional liquid and those of a solid crystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be...
s - SurfactantSurfactantSurfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
s - FoamFoam-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
s, gels, microemulsionMicroemulsionMicroemulsions are clear, thermodynamically stable, isotropic liquid mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. The aqueous phase may contain salt and/or other ingredients, and the "oil" may actually be a complex mixture of different hydrocarbons and olefins...
s - Granular materialGranular materialA granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact . The constituents that compose granular material must be large enough such that they are not subject to thermal motion fluctuations...
s - Complex plasmas
- MembraneBiological membraneA biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
s and other biological matterCellular componentCellular component refers to the unique, highly organized substances and substances of which cells, and thus living organisms, are composed. Examples include membranes, organelles, proteins, and nucleic acids... - Proteins, especially for Protein dynamicsNeutron spin echoNeutron spin echo spectroscopy is an inelastic neutron scattering technique invented by Ferenc Mezei in the 1970's, and developed in collaboration with John Hayter.In recognition of his work and in other areas, Mezei was awarded the first in 1999....
External links
- Pierre-Gilles de Gennes' Nobel Lecture
- Soft Materials
- Softmatterworld.org
- softmatterresources.com
- SklogWiki - a wiki dedicated to simple liquids, complex fluids, and soft condensed matter.