Cyclopentasiloxane is a slightly volatile cyclomethicone, which means its molecular structure is a cyclic version of the straight-chained dimethicone. This is a lightweight, fast-spreading emollient that leaves the skin with a very soft and silky after feel.
Supplied as a clear and colorless liquid, cyclopentasiloxane is often used as a solvent to dissolve other silicones in. It is useful for introducing silicones into an oil phase where they would otherwise be incompatible. This is a direct result of its molecular structure, which is comprised of a ring of silicone shielded by an oily ring of carbons. The carbons allow compatibility with non-silicone oils, such as jojoba seed oil or C12-15 alkyl benzoate.