The superabsorbent material inside these diapers is made up of a matrix of polymers that expand once dampness hits them. Polymers are a long chain of repeating units, and in this case, the absorbent material in diapers is based on the polymer polyacrylic acid.
A University of Michigan team has developed a technique to untangle these absorbent polymers and recycle them into materials similar to the gooey adhesives used in sticky notes and bandages. Their results are published in Nature Communications.
Broadly, recycling can be grouped into mechanical recycling and chemical recycling.
“Mechanical recycling is what most people think about: You separate different plastics based on their identities, chop them up into small pieces, melt them and reuse them, which lowers the quality of the product,” said U-M chemist Anne McNeil, corresponding author of the paper.
Mechanical recycling leads to lower quality materials because different companies’ plastics are constructed differently: The polymers can be different chain lengths or altered with different additives and dyes.
“There’s just so many problems, everything usually gets downcycled and ends up as carpet fibers or park benches,” said McNeil, whose lab focuses on the chemical recycling of plastics. “Chemical recycling is this idea of using chemistry and chemical transformations to make a value-added material, or at least a material as valuable as the original.”
