Head group various, zwitterionic

Based on the similarities in their behavior and characteristics of various types of detergents, it is essential that they are classified, and different types of detergents are categorized based on certain commonalities. Based on the nature of the hydrophilic head group, they can be broadly classified as ionic, nonionic, and zwitterionic detergents. Some of the examples of these surfactants are given in Table 26.1. 

Figure 14 Structures of zwitterionic phospholipids commonly used in the formation of liposomes and lipid bilayers. Shown are l-palmitoyl-2-oleoyl-in-glycero-3-phosphocholine (POPC), l,2-ipalmitoyl-in-glycero-3-phosphocholine (DPPC), and 1,2-dioleoyl-iw-glycero-3-phosphoethanolamine (DOPE). As is the case with POPC and DPPC, the acyl chains attached to the polar phosphatidylcholine head group may correspond to various fatty acids, which can be interchanged. DOPE, on the other hand, is comprised of the same acyl chains as DPPC and POPC but differs in the headgroup.

The most common surfactant dassiflcation is based on the nature of the head group anionic, cationic, zwitterionic, nonionic (various examples are given in Chapter 1). A special class of surfactants with high molecular weights (polymeric... 

Many syntheses of polymerisable surfactants have been described in the literature. These cover all possible combinations of the various surfactant classes (non-ionic, anionic, cationic and zwitterionic) and the classic polymerisable groups (vinyl, allyl, diallyl, acrylate, methacrylate, etc.). Once again, the polymerisable group may be located at different points on the molecule, although it is usually near the polar head, or at the end of the hydrophobic tail of the surfactant. It may even be a counterion. 

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