Multipoint anchoring

Fig. 9.2. Schematic representation of the multipoint anchoring of poly(oxyethylene) chains on high carboxyl polystyrene latex particles at low pH due to hydrogen bonding (inset).

It is further remarked that compression, involving as it does the exclusion of the segments from complete volume elements in space, is unlikely to be preferred to interpenetration wherein the segments have access to most (usually more than 70%) of those volume elements. If there is an elastic contribution to steric stabilization, it must surely arise, not directly from a high segment density, but from the loss of flexibihty concomitant with multipoint anchoring at the surface. 

Finally, we note that the maximum in the UCFT observed with poly(vinyl alcohol) is readily explicable without the elastic repulsion hypothesis. It merely requires the adsorbed, partially hydrolysed polymer to change from a relatively flat conformation at lower concentrations to a conformation more extended normal to the interface, and thus exhibiting reduced multipoint anchoring, at higher concentrations. This explanation is closely analogous to that proposed by Dobbie et al. (1973) for poly(oxyethylene) attached to polystyrene latices containing surface carboxylic acid groups. 

The multipoint anchoring of the polymer chains also ensures strong elastic (en-tropic) repulsion. This provides enhanced steric stabilization. 

The use of a strongly adsorbed ( anchored ) dispersant, for example by multipoint attachment of a block or graft copolymer. 

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