The Science and Technology of Liquid Crystals Peter J. Collings Department of Physics & Astronomy Swarthmore College June 21, 2007 Return to "Recent Talks" Page

Outline Introduction to Liquid Crystals Mechanical, Electrical, and Optical Properties Liquid Crystal Display Technology Chemistry of Liquid Crystals Biology of Liquid Crystals Return to "Recent Talks" Page

Phases of Matter Return to "Recent Talks" Page

Liquid Crystals L = 300 J/gmL = 30 J/gm solidliquid crystalliquid Return to "Recent Talks" Page

Orientational Order Order Parameter S = Return to "Recent Talks" Page

Order Parameter Return to "Recent Talks" Page

Smectic Liquid Crystals Return to "Recent Talks" Page

Typical Liquid Crystal Molecule Return to "Recent Talks" Page

Chiral Nematic Liquid Crystal Return to "Recent Talks" Page

Discotic Liquid Crystals Return to "Recent Talks" Page

Discotic Phases nematic columnar Return to "Recent Talks" Page

Lyotropic Liquid Crystals Return to "Recent Talks" Page

Lyotropic Phases Micelle (cross-section) Vesicle (cross-section) Return to "Recent Talks" Page

Liquid Crystal Phases of Aggregates Return to "Recent Talks" Page

Nematic Phase of Sunset Yellow Return to "Recent Talks" Page

Viscosity low viscosity high viscosity anisotropy! Return to "Recent Talks" Page

Polarization Return to "Recent Talks" Page

Birefringence Return to "Recent Talks" Page

Birefringence (continued) Return to "Recent Talks" Page

LCs between Crossed Polarizers E Return to "Recent Talks" Page

Nematic Liquid Crystal Return to "Recent Talks" Page

Smectic Liquid Crystal Return to "Recent Talks" Page

Chiral Nematic Liquid Crystal Return to "Recent Talks" Page

Selective Reflection condition for reflection: L 2 - L 1 = (P/2)(1+cos(  +  ))/cos  )= n if  =  and for n = 1, = Pcos  Return to "Recent Talks" Page

Temperature Sensors Return to "Recent Talks" Page

Liquid Crystal Display Return to "Recent Talks" Page

Twisted Nematic LCD Return to "Recent Talks" Page

Electrically Controlled Birefringence Return to "Recent Talks" Page

Computer Monitor Return to "Recent Talks" Page

Small Displays Return to "Recent Talks" Page

Light Shutters Return to "Recent Talks" Page

PDLC Windows & Displays Return to "Recent Talks" Page

Switchable Windows Return to "Recent Talks" Page

Liquid Crystal Droplets Return to "Recent Talks" Page

Biological Sensors Array of Antibodies in a Chromonic Liquid Crystal Crossed Polarizers Immune Complexes Return to "Recent Talks" Page

Synthesis of Liquid Crystals C - Core group (benzene, cyclohexane, pyrimidine rings) B - Bridging group (phenyl-, azo-, ester, Schiff’s base) L - Linking group (oxy-, carboxyl-) R - End group (hydrocarbon, -CN, -NO 2 ) X - Lateral group (-H, -F, -Cl, -Br, -NO 2 ) Return to "Recent Talks" Page

Double Twist Cylinders Return to "Recent Talks" Page

Simple Cubic Structure Return to "Recent Talks" Page

Blue Phase Single Crystals Return to "Recent Talks" Page

Phospholipid Bilayers Return to "Recent Talks" Page

Biology Cell Membranes Ordered substrate (hydrophilic, hydrophobic) Role of cholesterol (amount of order) Muscle Microfilaments (actin, myosin) Architecture (chiral nematic?) Microtubules (cytoskeleton, spindle fibers) DNA packing in chromosomes Return to "Recent Talks" Page

Medicine Sickle-Cell Anemia (abnormal hemoglobin aggregates?) Atherosclerosis (cholesterol esters in liquid crystal phase?) Anesthetics (environment of membrane proteins?) Cancer (order of microfilaments within cell?) Return to "Recent Talks" Page

Conclusions Liquid Crystals Are Interesting Scientifically Technologically Liquid Crystals Are Important Biology Chemistry Physics Engineering Liquid Crystals Are Beautiful! Return to "Recent Talks" Page