there are many types of organic silicone products, and they are ever-changing, but the vast majority of organic silicone products are generated from the most basic intermediates through grafting reaction, etc. it is octamethylcyclotetrasiloxane, commonly known as d4.
octamethylcyclotetrasiloxane (d4) is a colorless, transparent or opalescent liquid, flammable, and has no odor. it is a product obtained from dimethyldichlorosilane through a hydrolysis and synthesis process, and has been separated and distilled. the obtained compound is an important intermediate in the silicone industry. rings similar to d4 include d3/d5/d6. if these are mixed with d4, it is often called dmc.
click for detailed information: octamethylcyclotetrasiloxane iota d4 – (iotachem.com)
