Polyquaternium is a generic term for a class of synthetic, water-soluble polymers that contain quaternary ammonium groups in their molecular structure, giving them a permanent positive (cationic) charge. These polymers are widely used not only in water treatment, but also in personal care products (shampoos, conditioners), pharmaceuticals, and industrial applications.
The name "Polyquaternium" followed by a number (e.g., Polyquaternium-7, Polyquaternium-10) is assigned by the International Nomenclature of Cosmetic Ingredients (INCI).
Each number refers to a specific chemical structure:
Polyquaternium-6: Homopolymer of acrylamide and diallyldimethylammonium chloride (DADMAC) → essentially a type of copolymer similar to modified PolyDADMAC.
Polyquaternium-7: Copolymer of acrylamide and DADMAC (common in water treatment and cosmetics).
Polyquaternium-10: Cellulose-based polymer modified with quaternary ammonium groups (used in hair conditioners).
💡 In water treatment contexts, "Polyquaternium" often refers to Polyquaternium-6 or -7, which are functionally very similar—or identical—to cationic polyacrylamides or PolyDADMAC-based copolymers.
| Property | Description |
|---|---|
| Charge | Permanent cationic (from quaternary ammonium groups) |
| Solubility | Highly water-soluble |
| pH Sensitivity | Charge is independent of pH (unlike amine-based polymers) |
| Molecular Weight | Varies: medium to high (10⁵–10⁷ g/mol) |
| Function | Coagulation, flocculation, antistatic, conditioning |
In industrial and municipal water treatment, certain Polyquaternium types (especially PQ-6 and PQ-7) are used as:
Mechanism:
Neutralize negative charges on colloids (clay, organic matter, microbes) via electrostatic attraction.
May also provide polymer bridging if molecular weight is high enough.
Applications:
Clarification of surface water
Sludge dewatering aid
Pre-treatment for membrane filtration (reducing fouling)
Paper mill effluent treatment
⚠️ Note: In technical datasheets, these may be labeled as "DADMAC-acrylamide copolymer" rather than "Polyquaternium"—the latter term is more common in cosmetics.
Hair conditioners: Binds to negatively charged hair (especially damaged hair), reducing static and improving softness.
Shampoos: Provides anti-static and detangling benefits.
Contact lens solutions: Acts as a lubricant and antimicrobial agent.
Example:
Polyquaternium-10 = cationic cellulose → deposits on hair to improve manageability.
| Polymer | Composition | Primary Use | Charge Density |
|---|---|---|---|
| PolyDADMAC | Homopolymer of DADMAC | Water treatment coagulant | Very high |
| Polyquaternium-7 | Copolymer: DADMAC + acrylamide | Water treatment & cosmetics | High |
| CPAM | Acrylamide + cationic monomer (e.g., MAPTAC) | Flocculant, sludge dewatering | Adjustable (low–high) |
| Polyquaternium-10 | Quaternized hydroxyethyl cellulose | Hair conditioner | Moderate |
✅ Key Insight: Polyquaternium-7 used in water treatment is functionally equivalent to certain cationic polyacrylamides or modified PolyDADMAC products.
Residual monomers (e.g., acrylamide, DADMAC) are strictly controlled (<0.1% in most industrial grades).
Approved for use in drinking water treatment in many countries (e.g., under NSF/ANSI Standard 60).
In cosmetics, considered safe at typical use levels (0.1–5%).
Polyquaternium is a family of cationic polymers with permanent positive charges due to quaternary ammonium groups. While best known in shampoos and conditioners, specific types like Polyquaternium-6 and -7 are important water treatment chemicals, acting as coagulants or flocculants—especially in applications requiring strong charge neutralization without metal salts. In essence, they bridge the gap between cosmetic chemistry and industrial water purification.
