# Single-particle Brownian dynamics for characterizing the rheology of fluid Langmuir monolayers

## Introduction

The authors attempted to probe the rheology of fluid langmuir monolayers by tracking the diffusion of single particles at air-water interface. It is similar in spirit to the tracking of particles to study the rheology of three dimensional materials. The set-up is shown in figures 1 and 2. Polystyrene beads are interpersed in a bead of water in the presence of 3 different monolayers: N-palmitoyl-6-n-penicillanic acid (PPA), pentadecanoic acid (PDA) and L-α-dipalmitoyl- phosphatidylcholine (DPPC). The contact angle that the polystyrene beads make with the water can be measured using the set-up shown in figure 2 using the formula

where β is the water-glass contact angle.

The separation <L>

For brownian motions of particles completely submerged in fluid, the

## Results

## Personal Thoughts

## References

1. Single-particle brownian dynamics for characterizing the rheology of fluid langmuir monolayers, Sickert et al, EPL 2007