What it is
Aminoethylaminopropyl Methylsiloxane/Dimethylsiloxane Copolymer is a silicone polymer with pendant diamine groups (aminoethylaminopropyl) attached to a backbone of dimethylsiloxane units. The amine functionality enables selective adsorption onto damaged or chemically treated hair, where it forms a thin protective film that reduces friction, improves wet and dry combing, and adds shine. In skin care, it provides a silky, non-greasy feel and improves the spreadability of emulsions. Available in viscosities ranging from roughly 300 to 1,500 cSt, it is used across rinse-off and leave-on hair conditioners, shampoos, serums, and hair gels. The amine groups also confer antistatic properties, helping to tame flyaways. Unlike non-functional dimethicone, the polar amine groups give this polymer substantivity to negatively charged hair proteins, making it more conditioning on a weight-for-weight basis.
Safety & warnings
The concentrated bulk material is classified as a skin and eye irritant (H315, H319) and may cause respiratory sensitization at high vapor concentrations; GHS signal word Danger applies to the raw chemical. In finished cosmetic products it is used at low levels where these hazards are not expected to apply. The CIR Expert Panel assessed closely related amino-functional dimethicone polymers (amodimethicone group) and concluded they are safe as used in cosmetic formulations when formulated to be non-irritating. Persons with silicone sensitivities should be aware of its silicone polymer nature.
Origin & sourcing
Synthetic polymer produced by co-condensation or equilibration of aminoethylaminopropyl methylsiloxane monomers with dimethylsiloxane units under acid or base catalysis. The resulting clear to slightly turbid liquid is a mixture of chain lengths, characterized by amine content (aminoethylaminopropyl fraction typically 2–24 mol%) and viscosity. CAS 71750-79-3.
History
Amino-functional silicones emerged as specialty personal care ingredients in the 1980s and 1990s as formulators sought silicone polymers with enhanced substantivity to keratin. Aminoethylaminopropyl variants, offering a diamine pendant group for stronger fiber adhesion, were developed and commercialized by silicone manufacturers including Shin-Etsu and Momentive. The ingredient is listed under TSCA (US EPA) and appears in international INCI nomenclature as a recognized cosmetic conditioning polymer.
Questions everyone asks
What does this ingredient do in hair care products?
It conditions hair by selectively adsorbing onto the surface of hair fibers, especially in damaged areas, forming a thin film that reduces friction, improves wet combing and detangling, adds shine, and reduces static charge.
Is it the same as amodimethicone?
It is essentially the same chemical class. Amodimethicone is the common INCI name used when the polymer has terminal amine groups, while Aminoethylaminopropyl Methylsiloxane/Dimethylsiloxane Copolymer specifies the pendant diamine group structure.
Does it build up on hair?
Amino-functional silicones can accumulate with repeated use, potentially making hair feel heavy over time. Using a clarifying shampoo periodically helps remove buildup. Rinse-off formulations generally deposit less residue than leave-on products.
Is it safe for use in sunscreens and daily cosmetics?
Based on CIR safety reviews of the amodimethicone class, these polymers are considered safe as used in cosmetic formulations at typical concentrations. They are used globally in hair care and skin care products.