A Safer, Better, & Coral-Friendly Sunscreen Coming Soon (Hopefully)

While visiting the Great Barrier Reef in 2010, Lei Tao, a chemist at Tsinghua University, was inspired to create a coral-friendly sunscreen. During his visit, Tao was impressed by the beautiful coral, and upon learning that sunscreen is one of the causes of coral bleaching he knew that he wanted to do something about it. Tao and his team began formulating different ring-shaped molecules using an existing UV filter (avobenzone) as a reference molecule1.

Figure 1: Chemical Structure of Avobenzone2

The overall goal for making a new sunscreen is to block UV radiation with molecules that are too big to penetrate skin, coral, or algae. At this time, the more common organic UV filters in sunscreens (including avobenzone) have lower molecular weights and can disrupt marine environments. Studies have been conducted on mice and the results look promising: the polymeric UV filter is more effective at preventing sunburn than existing sunscreens. 

From there, Tao and his team were able to utilize chemical reactions that allowed them to link the different ring-shaped molecules together in different combinations. They accomplished the formation of new molecules through free radical polymerization (FRP), which is a polymerizing approach by which successive addition of free radicals takes place to form a polymer unit3.

Figure 2: Example of FRP Mechanism3

The figure below (Figure 3) depicts the chemical structures of three new UV polymer filters created by Tao and his team, in addition to oxybenzone and avobenzone, which are harmful to coral. Out of the three filters Tao’s team formulated, studies showed that P(3) is the most promising, as it was better at UV protection than the conventional sunscreen ingredients. 

Figure 3: Chemical Structures of UV Polymer Filters1

While these filters are an exciting discovery, Tao and his fellow researchers noted that they are not biodegradable, given their backbone structure. The group’s goal is to combine their structures with other compounds to ensure that a “final product” will be fully biodegradable and more environmentally friendly.

1. https://www.chemistryworld.com/news/a-safer-coral-friendly-sunscreen-is-on-the-horizon/4017077.article

2. https://pubchem.ncbi.nlm.nih.gov/compound/Avobenzone

3. https://byjus.com/chemistry/free-radical-polymerization/#:~:text=What%20is%20a%20Free%20Radical,cationic%2C%20anionic%20and%20coordination%20polymerization.