The process of self-assembly is ubiquitous in nature occurring in many wide-ranging structures from cell membranes, which are central to life, itself to high technology applications such as liquid crystal displays. The conditions that are necessary for molecules to organize and form self-assembled structures depend in very critical ways on subtle interaction forces and the delicate balances between them.
The class of substances collectively known as liquid crystals is intriguing because they exhibit physical properties that are between those found for solids and liquids. Nature has used these substances for eons before humans even found uses for them. Did you know that the cholesterol, a substance that we love to hate, is a liquid crystal? Did you know that the humble slug has been using these high-tech substances in the form of its mucus? The slug changes the alignment of the molecules in the mucus secretion to affect the fluid's viscosity, depending on the ground that it is crossing. This module specifically discusses the example of liquid crystals.
Key concepts:
- Four states of matter
- Physisorption, Van der waals forces and hydrogen bonding
- Hydrophobic and hydrophilic interactions
- Polar and non polar moieties in a molecule
- Shape of molecules and the relative strengths of intermolecular forces affect macroscopic properties of substances.
- Liquid crystals can be viewed as models for biological membranes.
- Properties of liquid crystals can be exploited for many applications.
- How humans exploit the properties of liquid crystals for everyday applications
Learning Objectives:
After completing this module, you will be able to:- Describe the four states of matter
- Explain the concepts of hydrophobic and hydrophilic interactions
- Describe polar and non-polar moieties in a molecule as related to liquid crystals
- Explain the similarities of biological membranes and liquid crystals
- List ways people use liquid crystals every day
- Discovery based learning via SPM Live!
In addition to addressing the needs of students at the beginning years of college, this module also addresses the following National Science Education Standards for grades 11-12:
Content Standard A- Abilities necessary to do scientific inquiry
- Understandings about scientific inquiry
- Structure of atoms
- Structure and properties of matter
- Chemical reactions
- Conservation of energy and increase in disorder
- Interactions of energy and matter
- Matter, energy, and organization in living systems
- Abilities of technological design
- Understandings about science and technology