The science of creating a long-lasting soap bubble

 January 17, 2023 7:41 PM

                              In addition to being a kid-favorite activity, blowing soap bubbles is both an artistic endeavour and a topic of interest for physicists. In an effort to comprehend the many mechanisms at work in these seemingly harmless formations, Emmanuelle Rio, François Boulogne, Marina Pasquet, and Frédéric Restagno from the Laboratory of Solid State Physics at the University of Paris-Saclay have been researching bubbles for years.

"Bubbles are significant because they are found in a variety of items, such as cosmetics, construction materials, and cleaning products, as well as in nature. For instance, sea foam contributes to the exchanges between the atmosphere and the water, according to Boulogne.

The team has now discussed a crucial phase in the existence of bubbles: their popping.

Taking the temperature 

In a recent work, Boulogne and Rio demonstrated the importance of bubble surface temperature to stability. "In certain instances, the thickness of the soap coating has been linked to the ageing and breaking of the bubbles. Recently, scientists started linking evaporation to the soap film's thinness. But we noted that heat transmission, which is related to evaporation, wasn't taken into consideration in our analysis," Boulogne stated.

The surface temperature of the bubbles was monitored by the researchers in order to further investigate this issue, and they discovered a substantial divergence from ambient temperature. According to Boulogne, the surface temperature of bubbles might drop by up to 8° Celsius.

Although temperature and bubble ageing are related, according to Boulogne, the effect of low temperatures on when the bubbles explode is still not well known and is expected to remain so for some time. "As of now, we don't have a model that can forecast this. It would take decades to solve the problem of understanding bubble stability, he added.

He reasoned that there are a number of variables to take into account while determining the stability of bubbles. "This includes the temperature, the rate of evaporation, the film-thinning, the phenomena of marginal regeneration (in which tiny patches that are lighter and thinner than the surrounding film rise to the top), and the geometry. It is quite difficult to include all of these aspects in a single model.

Building the perfect bubble 

Rio found the ideal mixture of chemicals to make bubbles endure longer while still being simple to generate, even if forecasting the stability of bubbles in various conditions may take some time.

Glycerol is the secret to lifespan. Other components include "optimum percentage" of dishwashing liquid and a lengthy polymer resembling guar gum, a naturally occurring gum. "Creating bubbles is made simpler by adding additional dishwashing liquid. However, they have shorter lives. To guarantee that bubbles are simple to create and remain for a sufficient period of time, you must use the proper amount of dishwashing liquid, according to Rio.

The formula was created by Rio and her colleagues in collaboration with the bubbles artist Pierre-Yves Fusier of France. It calls for combining 1 litre of water with 1 gramme of guar gum as well as dish soap, glycerol, and 100 millilitres of glycerol. This formula allowed Rio to produce bubbles in her lab that were 5 cm in diameter and lasted for an hour.

The stability of the bubbles may increase with the addition of glycerol, but Rio noted there is still uncertainty over how other chemicals would affect the bubbles' stability. "A hydroscopic substance called glycerol can help condense water. However, we are aware that the polymer and the surfactant (dishwashing liquid) can influence evaporation. Therefore, the next stage of our research is to determine how our formula affects evaporation, added Rio.

Evaporation, which Rio continued, is just one factor that contributes to bubble popping but is yet not fully understood. "Gravity must also be taken into account, since it contributes to surface thinning and the variability in film thickness. Because of all of this, it is quite challenging to forecast when a bubble would collapse, according to Rio.

Under the terms of a Creative Commons licence, this article has been taken from arstechnica. Go here to read the original article.