2007 Volume 48 Issue 4 Pages 653-657
We performed a Monte Carlo simulation for the formation of micelles in a ternary system composed of water solvent, oil solute (1%) and amphiphilic diblock copolymers (around 1%) on a simple cubic (3-D) lattice (51×51×51), using Metropolis algorithm. The diblock copolymers (50 chains) were expressed by the bond fluctuation model where each chain is composed of one hydrophobic end cube and four hydrophilic cubes connected by virtual fluctuating bonds.
We assumed that the configurational energy depends only on the attractive interaction energy (Epo) between a hydrophobic part of a copolymer and a neighboring oil cell, and the attractive interaction energy (Eoo) between neighboring oil cells. In this simulation, we drew a phase diagram and estimated the magnitudes of Epo and Eoo realizing the stable formation of micelles, which are composed of oil aggregates, hydrophobic part of copolymers, and hydrophilic part of copolymers, from inner to outer sides.
As a result, it was found that Epo≥1.9 kBT and Eoo≥2.3 kBT are needed to form micelles. Here Eoo should be the lowest value 2.3 kBT on the lower boundary (Epo=1.9 kBT), and Epo should be less than 2.6 kBT on the lower boundary (Eoo=2.3 kBT).