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A new degradable microbead could soon replace plastic exfoliants in skin cleansers.
The polymer spheres effectively remove permanent marker and eyeliner on animal skin samples and break down into molecules similar to sugars and amino acids, researchers report December 6 in Nature Chemical Engineering. The beads offer a more environmentally friendly alternative to microplastic beads, the scientists say.
In 2015, the United States banned companies from adding plastic microbeads to personal care products that get rinsed down the drain to prevent them from entering waterways where marine life might ingest them. Several countries have implemented similar bans, but others still allow companies to add plastic microbeads as scrubbers and exfoliants.
The new polymer could “really help move the field and get people thinking of different ways that we can make materials which don’t even have the ability to be a microplastic,” says Ana Jaklenec, a biomedical engineer at MIT.
Jaklenec and colleagues made the spheres, which average 76 micrometers across, from a type of polymer known as a poly(β-amino ester). Similar poly(β-amino esters) have been used for biomedical applications like carrying medicines through the body. The team tested how the spheres degraded in boiling water; after two hours more than 94 percent of the polymer had broken down into molecules related to sugars and amino acids.
Next, the researchers mixed the microparticles with soap foam and used the mixture to remove permanent marker from pig skin samples. Wiping the marks 50 times with the mixture removed about 74 percent of the ink, while wiping the marks with just soap foam removed about 38 percent of the ink. The cleansing mixture removed eyeliner even more effectively: Ten wipes with the mixture removed nearly twice as much eyeliner as soap foam alone.
The polymer microbeads also absorbed copper ions from water, suggesting that unlike regular plastic microbeads, they could cleanse skin of metals encountered in certain types of dust (SN: 9/26/24).
This performance boost could drive more companies to adopt more sustainable materials in the future, says Ben Elling, a polymer chemist at Wesleyan University in Middletown, Conn. who was not involved in the study.
“A lot of the fear of looking to more renewable or more degradable materials is that oftentimes they have worse properties than what you’re replacing,” Elling says. It’s easy to assume that there will always be a trade-off between performance and sustainability, he says, “but you can absolutely have the best of both worlds.”
