Lecture 1 Introduction
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Surface Phenomena
Transcript of Lecture 1 Introduction
What is Interfacial Phenomena?
• Key word is Interface– Boundary between 2 phases
• S-L, S-G, L-G primary ones we will be concerned with
• G-G does not exist – too low density, molecules can not be kept separate
• S-S exists, but not usually governed interfacially
• S-vacuum – vacuum not a phase – usually call this a surface
– Generally, Surface and Interface can be used interchangeably
Why do we care aboutInterfacial Phenomena?
• Everything has an interface/surface– Not always important
Nanostructures and Nanomaterials: Synthesis, Properties, and Applications By Guozhong Cao, Ying Wang
Why do we care aboutInterfacial Phenomena?
Nanostructures and Nanomaterials: Synthesis, Properties, and Applications By Guozhong Cao, Ying Wang
Why do we care aboutInterfacial Phenomena?
• Detergency• Glue• Foams• Mineral
separation• Water treatment• Paint• Gasoline pumping
• Milk• Breathing• Nanoparticles• Dispersions• Printing• Many more
Surface Energy/Tension
InterfaceUnfulfilled interactions
Force/tension reducing interfacial area
PTndAdG
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Surface Energy/Tension
28.72mmJ
Kmolecule
JxkBoltz 231038.1
Surface Active AgentSurfactant
• Major part of breathing is getting oxygen molecules through the lung cells surface and into blood.
• Surfactants modify surface/interfacial tension sufficiently, in this case blood-air, to allow us to breathe.
• Premature babies may not have these surfactants, so sprayed into their lungs
Questions• How can a metal needle “float” on a
water surface?• How can a teaspoon of olive oil suppress
waves and evaporation over several acres of water?
• Why do liquids stick to some surfaces better than others?
• How do soaps and detergent clean things?
• How can we make a foam/froth?• How can we dissolve oil in water with a
trace amount of a 3rd phase?• How can dense particles be suspended in
water almost indefinitely?
Colloids• Text – Principle of Colloid and Surface
Science• Colloid – Chapter 1 (please read)• Colloid – 1+ linear dimension
between 1 nm and 1 mm• Nanoscience – 1+ linear dimension
less than 100 nm – subset of colloidnano
colloid
