Polyethylene glycol 200 (CAS 25322-68-3)

Polyethylene glycol (PEG; /ˌpɒliˈɛθəlˌiːn ˈɡlaɪˌkɒl, -ˌkɔːl/) is a polyether compound derived from petroleum with many applications, from industrial manufacturing to medicine. PEG is also known as polyethylene oxide (PEO) or polyoxyethylene (POE), depending on its molecular weight. The structure of PEG is commonly expressed as H−(O−CH2−CH2)n−OH.

Because PEG is a hydrophilic molecule, it has been used to passivate microscope glass slides for avoiding non-specific sticking of proteins in single-molecule fluorescence studies.
Polyethylene glycol has a low toxicity and is used in a variety of products. The polymer is used as a lubricating coating for various surfaces in aqueous and non-aqueous environments.