Thermotropic LC’s – A Reminder
Lyotropic Liquid Crystals
• Molecules usually amphiphilic – hydrophobic and hydrophilic parts.
• How will these behave around water?
Hydrophilic head
Hydrophobic tail
Interaction With Water
• Orientational order induced by addition of solvent.
• Hydrophilic heads of the molecules are attracted to the water.
• What will the hydrophobic tails be attracted to?• What shapes may form?
One option…
• The exact shape formed will depend on the concentration and temperature.
Lyotropic Liquid Crystal Phases
Lyotropic LC’s in Nature
• Common in biological systems e.g. cell membranes.
How About Bubbles
• Soap bubbles are made of surfactants (amphiphilic) and water.
• How do the water and surfactants arrange themselves in a bubble?
What About Colour?
• Light can reflect on the inner or the outer bubble surface.
• Reflected light can interact constructively or destructively.
http://www.webexhibits.org/causesofcolor/15E.html
More on Colour
• The observed colour depends on thickness.• Where is the soap mixture the thinnest?
