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Dimethyldioctadecylammonium Chloride (DODMAC) - CAS 107-64-2

Dimethyldioctadecylammonium Chloride (DODMAC) - Properties, Applications, and Safety

Dimethyldioctadecylammonium chloride (DODMAC, CAS 107-64-2), also known as distearyldimonium chloride or distearyl dimethyl ammonium chloride (DSDMAC), is a quaternary ammonium compound belonging to the family of cationic surfactants. Its molecular structure features a central nitrogen atom substituted with two methyl groups and two long hydrophobic octadecyl (C18) alkyl chains. This unique "double-tailed" structure, combined with the cationic ammonium head group, confers strong surfactant properties, enabling the formation of stable hydrophobic films on various surfaces.

Chemical and Physical Properties

  • Molecular Formula: C₃₈H₈₀ClN

  • Molecular Weight: 586.5–586.64 g/mol

  • CAS Number: 107-64-2

  • EC Number: 203-508-2

  • Appearance: White to pale yellow powder, flakes, or paste

  • Melting Point: Wide reported range; 72–122°C, 36–44°C, or up to 160°C depending on purity and form

  • Decomposition Temperature: ~135°C

  • Density (at 88°C): 0.84 g/cm³

  • Solubility in Water: Extremely low, 1 pg–2.5 mg/L at 25°C

  • Vapor Pressure: Very low, <0.000001 Pa at 25°C

  • Stability: Decomposes on heating, producing toxic and corrosive fumes.

Mechanism of Action

As a cationic surfactant, DODMAC carries a positive charge that enables strong electrostatic adsorption to negatively charged surfaces such as hair keratin, textile fibers, and skin. The two long C18 hydrocarbon chains form a stable hydrophobic film that reduces friction, neutralizes static electricity, and imparts a soft, smooth feel. This dual action – electrostatic binding and hydrophobic film formation – underlies its effectiveness as a fabric softener, hair conditioner, and surface modifier.

Applications

Fabric Softeners and Textile Processing: DODMAC has been widely used as a fabric softener in retail, commercial, and textile mills. It coats textile fibers with a thin lubricious film, providing softness, antistatic properties, and improved hand feel. However, its use has strongly diminished in recent years in several EU countries due to environmental concerns.

Hair Care and Cosmetics: Used as a conditioning agent, antistatic agent, and emulsifier in hair rinses, conditioners, creams, and lotions. Forms a protective film on hair, improving softness, shine, and manageability.

Surface Coatings: Used in creating hydrophobic, water-repellent surfaces for textiles, automotive, and other industrial applications.

Antimicrobial Agents and Disinfectants: Effective in formulating antimicrobial products for healthcare disinfectants and antiseptics.

Organoclay Modification: Used to activate organic clays (bentonites) by ion exchange, modifying their surface properties.

Drug Delivery and Nanotechnology: Serves as a surfactant in the synthesis of nanoparticles and liposomal drug delivery systems. Cationic liposomes containing DODAC have been studied for antibacterial applications.

Asphalt Emulsifiers and Other Applications: Used as an asphalt emulsifier, leveling agent for acrylic fibers, dye additive, and in sugar refining.

Safety and Toxicology

  • Health Hazards: DODMAC is corrosive to the eyes and irritating to the skin. Inhalation of dust may cause coughing.

  • Fire and Explosion: Combustible; gives off irritating or toxic fumes in a fire.

  • Environmental Impact: DODMAC is toxic to aquatic organisms. It is not readily biodegradable, and its removal in wastewater treatment plants (ca. 95%) is mainly due to adsorption onto sludge. The most sensitive environmental species is the alga Selenastrum capricornutum.

  • Low Acute Toxicity: The substance has low acute oral and dermal toxicity. Negative results in an Ames test and an in-vitro chromosomal aberration test indicate no genotoxicity.

  • Regulatory Status: DODMAC is classified with hazard symbols Xi (Irritant) and N (Dangerous for the environment).

Storage and Handling

DODMAC should be stored in tightly sealed containers in a cool, dry, well-ventilated area, away from strong oxidizing agents and sources of ignition. Vacuum spilled material; moisten first to prevent dusting. Use appropriate personal protective equipment: protective gloves, safety goggles, and respiratory protection when dust is present. Do not let the chemical enter the environment.

Conclusion

Dimethyldioctadecylammonium chloride (DODMAC, CAS 107-64-2) is a versatile double-tailed cationic surfactant valued for its excellent softening, conditioning, antistatic, and film-forming properties. Its applications have spanned fabric softeners, hair care, cosmetics, surface coatings, disinfectants, and nanotechnology. However, its low biodegradability and aquatic toxicity have led to reduced use in certain applications, particularly in Europe, and necessitate careful handling and environmental management. Ongoing research continues to explore its potential in drug delivery systems, antimicrobial formulations, and advanced materials.

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