General Classification of Polymeric Surfactants

Perhaps the simplest type of a polymeric surfactant is a homopolymer, that is formed from the same repeating units, such as PEO or poly(vinyl pyrrolidone). These homopolymers have minimal surface activity at the O/W interface, as the homopolymer segments (e.g., ethylene oxide or vinylpyrroUdone) are highly water-soluble and have little affinity to the interface. However, such homopolymers may adsorb significantly at the solid/liquid (S/L) interface. Even if the adsorption energy per monomer segment to the surface is small (fraction of kT, where k is the Boltzmann constant and T is absolute temperature), the total adsorption energy per molecule may be sufficient to overcome the unfavourable entropy loss of the molecule at the S/L interface. 

The most convenient polymeric surfactants are those of the block and graft copolymer type. A block copolymer is a linear arrangement of blocks of variable 

Various molecules are available, where n and m are varied systematically. Trifunctional products are also available where the starting material is glycerol these have the structure  

Tetrafunctional products are available where the starting material is ethylene diamine these have the structures  

The above polymeric triblocks can be applied as dispersants, whereby the assumption is made that the hydrophobic PPO chain resides at the hydrophobic surface, leaving the two PEO chains dangling in aqueous solution and hence providing steric repulsion. Although these triblock polymeric surfactants have been widely used in various appHcations suspensions, some doubt has arisen as to how effective these can be. It is generally accepted that the PPO chain is not sufficiently hydrophobic to provide a strong anchor to a hydrophobic surface. 

---

The first section of this chapter describes the solution properties of polymers, and this is followed by a general classification of polymeric surfactants. Examples are provided of polymeric surfactants and polyelectrolytes that are used as dispersants and emulsifiers. 

In this overview, the first section will on general classification of polymeric surfactants. This is followed by a section on preparation of polymeric snrfactants, with particular reference to sugar-based molecules. This is followed by a discussion of their solntion properties. The next section will be devoted to the adsorption of polymeric snrfactants at the solid/liquid (S/L) interface, whereby a summary will be given to some of the theoretical treatments and the methods that... 

This chapter will start with a short account of the general classification and description of polymeric surfactants. This is followed by a summary on then-solutions properties. The adsorption and conformation of polymeric surfactants at the solid-liquid interface will be discussed at a fundamental level and some experimental results will be presented to illustrate the prediction of the theories. The interaction energies between particles or droplets containing adsorbed polymeric surfactants will be briefly described. The final section will give some applications of polymeric surfactants in suspensions, emulsions, and multiple emulsions. 

---