Aminofunctional Siloxane (Dimethyl Methyl Aminoethylaminoisobutyl Siloxane)

Aminofunctional siloxane (CAS 831241-93-1) is a methoxy- and hydroxy-terminated siloxane copolymer bearing diamine functional groups (aminoethylaminoisobutyl side chains). It is used as an adhesion promoter in spray sealants and coatings — the amine groups have chemical affinity for the hydroxyl and carbonyl sites on automotive clear coat, anchoring the silicone film to the paint surface.

This ingredient is distinct from the closely related amino-functional fluids (e.g., CAS 102782-92-3) that appear in other sealant and personal care formulations. The specific CAS 831241-93-1 appears in SDS formulations where the amine functionality is provided through an isobutyl spacer chain.

Health: At the ingredient level, this material carries H315 (skin irritation Cat 2) and H319 (eye irritation Cat 2A). At formulation concentrations of 0.3–1.2% in consumer spray sealants, these GHS codes propagate to the mixture — this ingredient is the irritant driver in products like Optimum Opti-Seal where H315/H319 appear in SDS Section 2. Standard protection: nitrile gloves and safety glasses during application.

Environment: Not classified for aquatic toxicity. Not PFAS. Biodegradability data is limited (typical of siloxane polymers). Bioaccumulation potential is low due to the polar amine groups (lower log Kow than non-functionalized siloxanes). Used at low concentrations in consumer products.