Effect of Nonionic Polymers on Particle Deposition

Nonionic polymers can be of the synthetic type such as polyvinylpyrrolidone or natural such as many polysaccharides. The role of nonionic polymers in particle deposition depends on the manner in which they interact with the surface and particle to be deposited. With many high molecular weight polymers, the chains adopt a conformation forming loops and tails that may extends several nm from the surface. If there is not sufficient polymer to fully cover the surfaces, bridging may occur, resulting in enhancement of deposition. In contrast, if there is sufficient polymer to cover both surfaces, the loops and tails provide steric repulsion, thereby reducing deposition. 

Polysaccharides are sometimes referred to as polyglycans or hydrocolloids . Most cosmetically interesting polysaccharides are primarily composed of six-membered cyclic structures known as pyranose ring (five carbon atoms and one oxygen atom). Many polysaccharides form helices, which is a tertiary spatial configuration, arranged to minimize the total energy of the polysaccharide (e.g. xanthan gum). 

The behaviour of polysaccharides is critically influenced by the nature of the substituent groups bound to the individual monosaccharides (natural or synthetic). Anionic charges may also occur in natural polysaccharides and this will have a big influence on the adsorption and conformation of the polymer chain. 

The effect of polysaccharides on particle deposition is rather complex, and depends on the structure of the molecule and interaction with other ingredients in the formulation. 

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