Polymers & Plastics
Although I already explained polymers briefly in the article on methyl methacrylate and poly(methyl methacrylate), I wanted to write a more in depth explanation of polymers.
Polymers are the result of a polymerization reaction. I think the best way to explain this is with Lego. Within Lego, you have different building bricks. You have white bricks, blue bricks, red bricks, yellow bricks and so forth. You have bricks with four studs on them, and bricks with six or eight studs. If you take a brick, and place it onto the next, you are building a column. Building with Lego has a lot of similiarities to a polymerization reaction. You have individual units of small molecules, which you can bond to each other.
I have only seen two major polymerization reactions (I’m a biologist, not a chemist, so excuse me if I exclude some possibilities) in cosmetic science. The first one is the formation of the most common polymer, by the breaking a double bond. A double bond can be found in a molecule (a brick), mostly between two carbon atoms. Oxygen is also known to form double bonds (other atoms as well).
As shown in the figure above, carbon atoms (and also oxygen atoms) are going to form a double bond to make sure to get the necessary 4 (carbon) or 2 (oxygen) bonds. In a polymerization reaction, another molecule is present to which a carbon atom can bond. The double bond breaks and both carbon atoms form the fourth bond with another molecule.
A polymer can consists of a large number (10.000+) of molecules, hence the ~ sign on both ends. Another polymerization reaction is shown in the photo of my old science journal above, when a hydroxyde (OH, also known as the ‘alcohol’ group) reacts with another hydrogen atom and thus forms water (H2O). The carbon atom then bonds with the other oxygen atom and a polymer is formed.
Polymers are considered plastics and are used in cosmetics as thickening or film forming (for instance in nailpolish) agents. If you find a plastic or a polymer in a ingredientlist, please do not flush it through the sink. The plastic ends up in the ocean, where it can contribute to the plastic soup that already is floating around there, killing sea animals by choking or contributing to the malformation of a sea animal. Rinse the product off with a make up removal wipe or by using a cotton pad and some cleanser.
I hope the topic of polymers and plastics is even clearer now. If not, just ask a question in the comments.
Until next time,