Everyone knows the glow sticks you got when you were at a kids disco. And these things prove that chemistry is everywhere around you although you sometimes don't even notice it. For that reason, I really like these!
The glow sticks are made of a plastic tube with hydrogen peroxide and a glass tube in it. The glass tube is often filled with diphenyl oxalate and a fluorescent pigment. When you bend the stick, the glass tube will break, and the diphenyl oxalate reacts with the hydrogen peroxide. After the reaction two molecules of phenol and one molecule of 1,2-dioxethanedion are formed. The 1,2-dioxethanedion decomposes to carbon dioxide spontaneously and emits energy. This energy is used by the fluorescent pigment which causes it to go to the exited state. In the exited state the pigment emits photons, this is visible as the awesome fluorescent light! This reaction is called chemiluminescence.
The most used colours for glow sticks are pink, green, blue, orange and yellow. For each colour a different pigment is used. For pink this is Rhodamine B, for green 9,10-Bis(phenylethynyl)anthracene, for blue 9,10-Diphenylanthracene, for orange Rubrene and for yellow this is 1,8-dichloro-9,10-bis(phenylethynyl)anthracene. All these molecules are quite big and complex. The thing they have familiar is the way of reacting and the possibility to be a fluorescent pigment.
Sadly enough, glow sticks can only be used once. The reaction emits light for over twelve hours but will slowly lose intensity. While the light isn’t completely gone yet, it is possible to refrigerate the sticks to give them a temporary boost for a short time. After a few days most glow sticks have lost their light completely and will turn white. Sometimes the colour will be slightly visible when held in bright light. Especially the yellow and pink ones will remain coloured.
I always enjoyed wearing glow sticks and if I’m honest, I’m still fascinated by them. I already understood how they worked in theory, but now I know a lot more and a lot more detailed! The next time I get the chance to bend a glow stick to light it up, I’ll take a moment to realize how awesome these things are.
Super interesting and explained really well!