Preparation of Cholesteryl Ester Liquid Crystals

Procedure based on G. H. Brown and J. J. Wolken, Liquid Crystals and Biological Systems, Academic Press, NY, 1979, pp. 165-167 and W. Elser and R. D. Ennulat, Adv. Liq. Cryst. 2, 73 (1976).

 One of the principal advantages of liquid crystals is their ability to map out thermal regions of different temperature. These cholesteric-nematic liquid crystals reversibly change color as the temperature changes. As long as the mixture is stored in a sealed container it can be prepared months in advance, although the sample may need to be remelted to mix.

Safety

Wear eye protection

Procedure

Step 1. Place 0.65 g cholesteryl oleyl carbonate, 0.25 g cholesteryl pelargonate, and 0.10 g cholesteryl benzoate in a vial. S

Step 2. Melt the solid in a sample vial using a hair drier, heat gun, or oven.

Step 3. While the mixture is still liquid, divide into several vials.

Step 4. The product changes color as it cools. Different compositions change color over different temperature changes.

Step 5. Touching the vial changes the temperature and results in color changes.

Materials

Use these materials with normal chemical precautions. Solids should not be inhaled and contact with skin, eyes, or clothing should be avoided. Wash thoroughly after handling.
  • Cholesteryl oleyl carbonate, Aldrich 15,115-7
  • Cholesteryl pelargonate (Cholesteryl nonanoate), Aldrich C7,880-1
  • Cholesteryl benzoate, Aldrich C7,580-2
  • 0.01 g balance, vials, heat gun or hair dryer
  Cholesteryl
oleyl
carbonate
Cholesteryl
pelargonate
Cholesteryl
benzoate 
Transition range,
degrees C
 Different compositions 
change color over
different temperature
ranges.
 0.65g  0.25g   0.10g  17-23
 0.70g  0.10g  0.20g   20-25
 0.45g  0.45g   0.10g  26.5-30.5
 0.43g  0.47g   0.10g  29-32
 0.44g  0.46g   0.10g  30-33
 0.42g  0.48g  0.10g  31-34
 The movies above use
the composition in the 
top row of the table.
 0.40g  0.50g  0.10g  32-35
 0.38g  0.52g  0.10g  33-36
 0.36g  0.54g  0.10g  34-37
 0.34g  0.56g  0.10g  35-38
 0.32g  0.58g  0.10g  36-39
 0.30g  0.60g  0.10g  37-40

YouTube Link:

http://www.youtube.com/watch?v=Q_Yem5v8JrI