What it is
Polyacrylamide is a polymer formed with monomers of Acrylamide, a toxic substance.
What it does
Polyacrylamide is used in cosmetic and personal care products as a film former agent: it creates a thin film on skin that moisturizes and binds water in. This film also prevents hair from absorbing moisture so that hairstyles will hold for hours.
In addition, it can be used in sunscreens to help the product remain on the skin after water immersion (you still need to reapply though!) and in cleansers as an abrasive.
Polyacrylamide is also used in a product called Aquamid, a filler injected to fill in wrinkles, enhance cheekbones and get plumper lips among other things. The treatment is considered permanent. It can potentially be removed, but it’s difficult.
Unlike Acrylamide, Polyacrylamine isn’t considered toxic. However there are concerns about a possible contamination as Polycrylamide could potentially secrete Acrylamide. According to the FDA Polycrylamide can be used in cosmetics and personal care products if it contains less than 0.2% of acrylamide units. In addition, they limited the residues of acrylamide in finished products to 5ppm.
Polyacrylamine molecules are too big to penetrate the skin, but there are concerns about injections (Aquamid). The treatment is considered safe, but there can be problems with bacteria infections and it still raises questions about potential release of Acrylamide.