chapter  1
36 Pages

1

I. Surfactants and Self-Assemblies of Surfactants.......... 2 II. Adsorbed Surfactant Layers on Solid Surfaces ........... 6 III. Micelles and Solubilized Systems ................................. 8

A. Theoretical Aspects ................................................. 8 B. Experimental Aspects ........................................... 12 C. Solubilized Systems............................................... 16 D. Water-Soluble Polymer/Surfactant Systems........ 16

IV. Microemulsions............................................................. 17 V. Vesicles .......................................................................... 21 VI. Lyotropic Liquid Crystals (Mesophases) .................... 26 VII. Conclusion: Importance of Dynamic Aspects of

Surfactant Self-Assemblies.......................................... 30 References.............................................................................. 31

I. SURFACTANTS AND SELF-ASSEMBLIES OF SURFACTANTS

The word

amphiphile

first introduced by Hartley

refers to a large class of compounds whose molecules contains moieties that have affinity for water (or are waterlike) and moieties that have affinity for oil (or are oil-like). Many biological compounds, most notably

phospholipids

, which make up living cell walls, as well as many

drugs

are amphiphilic. So are the so-called

surfactants

, compounds whose molecules are made up of one hydrophilic moiety, referred to as the

head group

, which is covalently bonded to one hydrophobic moiety, generally a single or double alkyl chain also called the

tail

. The head group may be nonionic (a short poly(ethylene oxide) segment or a sugar), ionic (anionic or cationic), or zwitterionic. The alkyl chain may be a hydrocarbon, a perfluorocarbon, or a mixed hydrocarbon/perfluorocarbon group. It may also be partly aromatic.