Interactions In Soft Matter 2. β-decay) 3. 4. Etc.
Interactions in soft matterThe forces of nature:1. Strong forces hold protons and neutrons together (exchange of mesons)2. Weak interactions are involved in some kinds of radioactive decay (β-decay)3. Coulombic or electrostatic forces hold most matter together4. Gravitation forces affect tides, hold us to the earth etc.Israelachvili, Intermolecular and Surface ForcesComplete and precise descriptions based on quantum mechanics existfor the Coulombic/Electrostatic force. These are used to describematerials.Wiki: Soft matter comprises a variety of states, perhaps bestdistinguished as being dominated by energies of the order of roomtemperature thermal energy. At these temperatures, quantum aspectsare generally unimportant.Soft matter meansMaterials 200BOr does it ?Ram Seshadri x6129 seshadri@mrl
Interactions in soft matterGravity and the forms of potentials:Gave rise to the historical belief that the forces between atoms, moleculesetc. could be expressed in a form that related force (or the potential) to theinteratomic/intermolecular distance.The first serious attempts arose from the van der Waals equation of state:If, then one recovers the ideal gas.represents the effect ofattraction between molecules and , their volume. Mie in 1903 proposed thegeneral form of an intermolecular potential:Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterLimits on a potential of the form:In a homogeneous medium, the total energy from a central molecule to allmolecules as one moves to some maximum length is given by the integralfrom the molecular radius to the maximum length:Note thatis a necessary condition for the more distant molecules tonot dominate in the potential. What about gravity and luminous intensityfrom the stars ?Israelachvili, Intermolecular and Surface ForcesMaterials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterThe hard sphere potential:This is sufficient to crystallize materials (the Alder transition):Entropy favors crystallization !V. J. Anderson and H. N. W.Lekkerkerker, Nature 416(2002) 811-815: Insights intophase transition kinetics fromcolloid scienceMaterials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterThe Lennard-Jones potential (John Edward Lennard-Jones, 1894-1954):Ar2The attractive part is called thevan der Waals attraction or(London) dispersion force. Therepulsive part comes from thePauli exclusion principle and theexponent is usually chosen forconvenience.wikipediaMaterials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterThe dispersion force (van der Waals), London . Arises from distortions in theelectron cloud around nucleii:No dipole/quadrupoleInstantaneous quadrupoleInstantaneous dipoleThe London dispersion arises because of instantaneous dipoles forming inthe floppy electron clouds of large atoms and molecules. It can trace itsorigins to the Heisenberg uncertainty principle.The form is:Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterWhy do we need potentials ?1.2.3.Colloidal/soft matter systems are typically very large, with many points ofcontact (interaction). So despite the individual interactions being weak,the net effects are significant.Computations on large systems (frequently) preclude complete quantummechanical descriptions.Standard applications of DFT, for example can fail to describe van derWaals type interactions.Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterColloidal particles are particles typically between 1 and a 1000 nm that can bedispersed (suspended) in fluids and for which Brownian forces are usuallystronger than gravitation the particles do not (usually) precipitate. Modelcolloidal particles are made of monodisperse spheres (polystyrene, silica )In suspension, the particles are attracted together by London dispersion. Howdoes one keep them apart ?In water, the colloidal particles can have like charges, for example, throughattaching ionisable acid groups on the surface. These like charges repel, butthe repulsion is usually screened. DLVO theory (Deryaguin-Landau-VerweyOverbeek) puts together the attractive London part and the screened Coulombrepulsion:Attraction:Repulsion:Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterThe screened Coulomb potential is given by Debye-Hückel theory, and arisesbecause of all the charges due to ions in solution.is the Debye screeninglength. When this is large, charges “see” one another easily, and when it issmall, they do not.Consequences for colloidal suspensions: In very clean (free from ions)solvents, the repulsions from the charges dominate.In the presence of ions, the Coulombic repulsion is strongly screened, andthe van der Waals attraction dominates.Thus for a suspension of colloidal spheres with ionisable surface groups,the phase behavior can be tuned.Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterPolymers and steric stabilization:Image colloidal particles in a non-polar solvent (an oil) of very low dielectricconstant whence the particles would not ionize, and would not charge. Howdoes one keep them apart ?Answer: Stick polymeric chains on them. Entropic effects keep the chainbunched up. For another particle to approach, the chains on that particle mustinterpenetrate which implies the chains must straighten out. This is notentropically favored.This is why gums are added to stabilize colloids (egg-whites in ice cream etc.)Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterWhat can you do with colloids ? www.colloid.nlNature 437 (2005) 235Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterNature 437 (2005) 235What can you do with colloids ?www.colloid.nlMaterials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterNature 437 (2005) 235What can you do with colloids ?www.colloid.nlMaterials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterNature Mater. 6 (2007) 202.Materials 200BRam Seshadri x6129 seshadri@mrl
Interactions in soft matterNature Mater. 6 (2007) 202.The atoms in the Lavesphase can be describedas interpenetratingdiamond or pyrochlorelattices. Removing oneleaves behind the other.Materials 200BRam Seshadri x6129 seshadri@mrl
The forces of nature: 1. Strong forces hold protons and neutrons together (exchange of mesons) 2. . Israelachvili, Intermolecular and Surface Forces Or does it ? Materials 200B Ram Seshadri x6129 seshadri@mrl Interactions in soft matter Gravity and the forms of potentials: Gave rise to the historical belief that the forces between atoms .
Pearl Green 455 Pearl Blue 465 Orange Pearl 470 Dark Blue 475 Garnet 480 Gold 801 Soft Lilac 802 Soft Yellow 803 Soft Orange 804 Soft Garnet 805 Soft Dark Blue 806 Soft Light Blue 807 Soft Pastel Green 808 Soft Pistachio Green 809 Soft Grey 810 Soft Black 128 Dental White 400 Yellow 405 Lilac 425 Silver Grey 435 Pearl
Soft Speech Booster Soft Speech Booster is a feature of VAC that provides increased level of soft gain at high frequencies. The feature en-hances the details of soft speech signals and is adapted to client’s individual needs and preferences for soft sounds and soft speech. The new Soft Sound Perception trimmer in Genie adjusts how the soft
Altistart 48 soft start - soft stop units The Altistart 48 soft start - soft stop unit is a controller with 6 thyristors which is used for the torque-controlled soft starting and stopping of three-phase squirrel cage asyn
2:1 Matter and Energy MATTER: anything that has mass and takes up space Three States (phases) of Matter 1. SOLID: matter with definite volume and shape 2. LIQUID: matter with definite volume but no definite shape 3. GAS: matter with no definite volume nor shape How does Matter Change? PHYSICAL CHANGE: c
switch". The goal of "soft switch" is to develop a standard PWM switch cell with built-in adaptive soft switching capabilities. Just like a regular switch, only one PWM signal is needed to drive the soft switch under soft switching condition. The core technique in soft switch development is a built-in adaptive soft switching circuit with
"switch" or other logic element) specifically for soft robots. We have directly integrated unidirectional, soft check valves into a soft robot to vent the combustion products of an explosion, which powered the soft robot (22). Wehner et al.(23) developed an entirely soft, autonomous
TUBE BENDER TUBE BENDER Maxi TUBE BENDER Maxi MSR Method: Manual 90 Manual 90 Manual 90 Working range: Copper 1 mm, soft 1 mm, soft Working range: Aluminium 1 mm, soft 1 mm, soft Working range: Precision steel 1 mm, soft 1 mm, soft Working range: Stainless steel 1 mm, soft Working range: MSR2 mm 2 mm Page56 57 58 Bending System Overview .
the timing constraints on these interfaces are quite stringent. An example of FPGA design using soft IP is illustrated in Figure 1. Processor Soft IP1 Main Design Hard IP Soft IP2 Fig. 1: Design containing soft IPs that connect to Hard blocks In order to guarantee the timing closure of these soft IP while avoiding excessive PnR runtime, FPGA .
