Surfactant Interactions with Skin Lec 4

Question 1

What is the CMC?

Answer 1

Point at which surfactant forms micelles.

Question 2

At how many carbons does irritation peak?

Answer 2

12

Question 3

Why C12 Maximum activity?

Answer 3

Hydrophobic Interactions are strong
Lower C chains have weaker hydrophobic interactions
Higher C chains cannot penetrate the matrix
CMC goes down as carbon chain lengths increase
Less monomer to interact.

Question 4

What happens with anionic surfactants at pH 9?

Answer 4

There is repulsion between acid groups and sulfate groups through electrostatic repulsion

Question 5

What happens with anionic surfactants at pH 3?

Answer 5

The surfactants bind and are attracted to one another through ionic attraction

Question 6

What happens to a cationic surfactant at pH 9?

Answer 6

The surfactants bind and are attracted to one another through ionic attraction

Question 7

What happens to a cationic surfactant at pH 3?

Answer 7

There is repulsion between the keratin fibers and the surfactant though electrostatic repulsion