surfactants, function and critical micelle concentration, micelle formation, function and use

What is a micelle?

A spherical arrangement of surfactant molecules with hydrophobic cores and hydrophilic shells in water.

Define Critical Micelle Concentration (CMC)?

The minimum surfactant concentration required for micelle formation.

What happens below the CMC?.

Surfactant molecules exist mostly as monomers.

What happens above the CMC?

Surfactant molecules form micelles.

What is the main driving force for micelle formation?

The hydrophobic effect (avoiding water ordering around tails).

How does increasing the hydrophobic chain length affect CMC?

It lowers the CMC

How does adding salt affect the CMC for ionic surfactants?

It lowers the CMC by screening head group charges.

Name two pharmaceutical uses of micelles?

Drug delivery and controlled drug release.

Where do the hydrophobic tails point in a micelle?

Toward the inside (core).

Where do the hydrophilic heads point in a micelle?

Toward the outside (interacting with water).

How does surface tension behave relative to CMC?

Decreases sharply up to the CMC, then remains constant.

What changes in solution properties occur at the CMC?

Changes in conductivity, osmotic pressure, and surface tension.

What is a surfactant?

A molecule with both hydrophilic and hydrophobic parts that reduces surface or interfacial tension.

Name two pharmaceutical functions of surfactants?

Emulsification and wetting agents.

What is the structure of a surfactant?

Hydrophilic head + hydrophobic tail.

What is Critical Micelle Concentration (CMC)?

The minimum concentration of surfactant needed for micelle formation.

What happens when surfactant concentration exceeds the CMC?

micelles begin to form

How does adding salt affect CMC in ionic surfactants?

Lowers the CMC by shielding head group charges.

What are micelles?

Aggregates of surfactant molecules with hydrophobic cores and hydrophilic shells.

Which part of the micelle traps hydrophobic substances?

the hydrophobic core

How does surface tension behave at concentrations below CMC?

Decreases sharply with increasing surfactant concentration.

Give two uses of micelles in pharmaceuticals?

Solubilization of hydrophobic drugs and drug delivery systems.

What type of surfactant has no charge on the head group?

nonionic surfactants

Give an example of an anionic surfactant?

Sodium lauryl sulfate (SLS).