Colloidal raw materials are water-soluble polymers that swell into colloids in water. In cosmetics, they offer various functions: binding and shaping solid powders, acting as binders, lubricating emulsions or suspensions, acting as emulsifiers, and thickening or gelling agents.
Water-soluble polymers used in cosmetics are mainly divided into two categories: natural and synthetic. Natural water-soluble polymers include starch, plant gums, and animal gelatin, but their quality is unstable, easily affected by climate and geographical environment, production is limited, and they are susceptible to spoilage by bacteria and mold. Synthetic water-soluble polymers include polyvinyl alcohol and polyvinylpyrrolidone, which are stable, have low skin irritation, and are inexpensive, thus replacing natural water-soluble polymers as the main source of colloidal raw materials. These are further divided into semi-synthetic and synthetic water-soluble polymers. Commonly used semi-synthetic water-soluble polymers include methylcellulose, ethylcellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and guar gum and its derivatives. Commonly synthesized water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, and acrylic polymers. These are used in cosmetics as adhesives, thickeners, film-forming agents, and emulsion stabilizers.
