Monomolecular films on the Langmuir surface balance

Introduction:

Surface active substances often form monomolecular layers at interfaces. Irwing Langmuir was the first to perform systematic studies on floating monolayers on water in the late 1910's and early 1920's. These studies led to him being awarded the Nobel prize. As early as 1920 he reported the transfer of fatty acid molecules from water surfaces onto solid supports. However, the first detailed description of sequential monolayer transfer was given several years later by Katherine Blodgett(8). These built-up monolayer assemblies are therefore referred to as Langmuir-Blodgett (LB-) films. The term "Langmuir film" is normally reserved for a floating monolayer.

Curriculum:

1. Introduction to Langmuir and Langmuir-Blodgett Films 2. KSV Minitrough instruction manual3. Additional background will be provided.

Type of teaching:

Self study and lab work under partly supervision.

Learning requirements:

The student must have aquired the following abilities:

• Understand the terms monomolecular layers and surface pressure/area isotherms.
• Be able to set up the Minitrough and make reproducible spread monolayers.
• Aquire pressure/area isotherms.
• Convert data and present isotherms i Origin.
• Interpret the isotherms in connection to surface conformation(s).

Lab exercises:

• Learn to use the instrument
• Measurement of a simple surface active alcohol or fatty acid.
• Measurement of a polymer or other complex surfactant.
• Possibly advanced procedures (penetration, kinetics).
• Writing of lab report.