Soap bubbles are beautiful and entertaining. They consist of a thin closed membrane of soapy water that traps air inside. Soap bubbles are round because of the way that water molecules in the membrane attract one another. But they only last from a few seconds up to a few minutes before they pop and disappear.
Why do they pop so soon? One reason is gravity, which causes the liquid to collect at the bottom of the floating bubble. This makes the top get thinner, down to a limit of about a few hundredths of a millimeter. When the membrane gets too thin, it breaks. Another reason bubbles pop is evaporation, which also makes the membrane get thinner as water disappears. Dust particles can also break the membrane and end the fragile bubble’s life.
In 2022 a team of French researchers reported that they had found a way to increase a bubble’s lifespan drastically. First, the researchers replaced the mixture of soap and water with a mixture of water and glycerol—a fatty substance found in soybeans and palm. Glycerol absorbs moisture from the air, counteracting the loss of water from the bubble by evaporation.
The second special ingredient was microscopically small plastic particles. These particles attracted the water to all parts of the bubble, counteracting the tendency of the top of the bubble to get thinner due to gravity. The researchers were astonished that, with these new ingredients, bubbles lasted for days or longer. So, they decided to wait to see how long the longest lasting would stay around. It was observed to last for four hundred and sixty five days without popping—more than a whole year!
