The everyday use of disposable diapers by children and some adults is one more application of materials called polymers. You polymers they are macromolecules (large molecules with a high molar mass) formed from the union of smaller molecules, which are called monomers.
There are many types and applications of polymers. At disposable diapers, specifically, began to be used in the 1980s and persist to this day due to its excellent ability to absorb liquids.
In this text, we will emphasize the disposable diaper chemistry. If we are going to talk about chemistry, we have to name substances. The chemical substance responsible for the absorption of liquids in diapers is sodium polyacrylate, whose structural formula is:
Structural formula of Sodium Polyacrylate
Polyacrylate is a polymer originated from the chemical reaction between an acrylic acid, which has three carbons, two oxygens and six hydrogen atoms per molecule, and sodium hydroxide (NaOH), a base inorganic.
The presence of sodium (Na) groups in this polymer causes it to become quite polar (has a pole negative and positive pole), which is ideal for it to interact with various water molecules, which are also polar.
Representation of the interaction between sodium polyacrylate and water molecules
As Polyacrylate is a macromolecule, it has the ability to interact with a large amount of molecules of water at the same time. Therefore, it is called superabsorbent, because has a great capacity forand water absorption.
A very interesting fact about Sodium Polyacrylate is that, for every 1 gram of this polymer, it can absorb 800 grams of water.
In addition to sodium polyacrylate, disposable diapers also have other important components, namely:
Cellulose Pulp: it is a natural polymer that is blended with sodium polyacrylate to further increase the material's liquid holding capacity.
Polypropylene plastic layer: This is the part of the diaper that comes into contact with the baby's skin and has the function of favoring the flow of liquid to the region with the superabsorbent.
Polyethylene Film: It is a hydrophobic material (which does not interacts with water) used to prevent liquid leakage out of the diaper.
Unfortunately, the excellent absorption capacity presented by psodium lyacrylate from disposable diapers contrasts with the pollution that he has been causing. It is estimated that a child uses 5670 diapers in their first two years of life. Thus, an absurd amount of diapers are dumped in dumps and landfills around the world.
The time it takes for sodium polyacrylate to be decomposed in nature varies from 250 to 500 years. Because of this, many scientists have invested time in discovering new superabsorbent polymers that can be broken down in less time.
By Me. Diogo Lopes Dias
