Polyquaternium-67: properties, uses, pros, cons, safety
Polyquaternium-67 (PQ-67) – conditioning cationic polymer (a quaternized, hydrophobically modified hydroxyethylcellulose derivative) used for combability, anti-static performance, slip, and to support deposition of benefit agents on hair.

2-Hydroxyethyl cellulose ether, reaction products with N,N,N-trimethyl-N-oxiranylmethylammonium chloride and N-dodecyl-N,N-dimethyl-N-oxiranylmethylammonium chloride

Synonyms: PQ-67, hydrophobically modified “quaternized hydroxyethyl cellulose” (technical description), SoftCAT™ (commercial family names)
INCI / Functions: antistatic, film forming, hair conditioning

Definition

Polyquaternium-67 is a family of cellulosic cationic polymers produced by functionalizing a hydroxyethylcellulose-type backbone with quaternary ammonium groups (permanent positive charge) and a controlled level of hydrophobic substitution. In practice, it combines two functional elements: (1) a cationic component that provides substantivity toward negatively charged surfaces (hair—especially damaged keratin and more anionic sites), and (2) a mild hydrophobic component that improves fiber affinity and sensorial payoff without the typical side effects of some conditioners (build-up or marked volume loss) when properly dosed.

In shampoos and surfactant systems, the most relevant practical mechanism is the formation of polymer–surfactant complexes and coacervates during dilution/rinsing: this promotes deposition of the polymer (and other benefit agents) on hair, improving wet comb, dry comb, softness, and static control. From an application standpoint, PQ-67 is valued because it can function across a broad window of surfactant systems while still enabling clear/low-haze products, and because it can act as a deposition aid for silicones and other lipophilic actives.

As a polymer, many properties (viscosity, stringiness, clarity performance, electrolyte tolerance) depend on the specific commercial grade and active content; therefore, procurement specifications and finished-product testing are integral to correct qualification.

Main uses

Cosmetics.
The primary application area is haircare, both in rinse-off products (shampoos, 2-in-1 shampoos, masks) and in selected leave-on products, where the goal is improved combability, softness, slip, and reduced flyaways and static. In “clear” shampoos, PQ-67 is selected when measurable conditioning is desired without losing transparency aesthetics and without overly complicating rheology through unwanted associative thickening. In silicone 2-in-1 systems, it is often used to improve silicone deposition on fiber, with a positive impact on slip and a more disciplined post-rinse feel.

In formulas targeting treated or damaged hair, the cationic character supports more selective anchoring where the fiber is more anionic, delivering targeted sensorial improvement (reduced friction, easier detangling). In addition, as a light film former, it can contribute to a more uniform cuticle surface, supporting shine and a more “silky” touch, especially when the formula also contains emollients or silicones.

In skincare, use is typically secondary and related to film/sensory functions in specific architectures (e.g., cleansers or systems where deposition of emollients is desired); in market practice, however, it remains predominantly a hair-conditioning ingredient.

INCI Functions

Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.

Film-forming agent. It produces a continuous ultra-thin film with an optimal balance of cohesion, adhesion and stickiness on the skin or hair to counteract or limit damage from external phenomena such as chemicals, UV rays and pollution.

Hair conditioning agent. A large number of ingredients with specific purposes can co-exist in a hair shampoo: cleansers, conditioners, thickeners, mattifying agents, sequestering agents, fragrances, preservatives, special additives. However, the indispensable ingredients are the cleansers and conditioners as they are necessary and sufficient for hair cleansing and manageability. The others act as commercial and non-essential auxiliaries such as: appearance, fragrance, colouring, etc. Hair conditioning agents have the task of increasing shine, manageability and volume, and reducing static electricity, especially after treatments such as colouring, ironing, waving, drying and brushing. They are, in practice, dispersing agents that may contain cationic surfactants, thickeners, emollients, polymers. The typology of hair conditioners includes: intensive conditioners, instant conditioners, thickening conditioners, drying conditioners.

Identification data and specifications

Chemical-physical properties (indicative)

Functional role and practical mechanism

Formulation compatibility

Polyquaternium-67 is typically designed to perform well in cleansing systems (especially anionic/amphoteric). In these contexts, conditioning is largely driven by surfactant complexation and coacervate formation upon dilution, which supports deposition on hair. This is a performance advantage, but it brings several key formulation control points:

• Dose and clarity window. In “clear” systems, haze can increase if the dose is high or if salinity/electrolytes push formation of visible complexes. Grade selection (charge and hydrophobicity) and the surfactant balance are decisive.

• Interactions with anionic polymers. Co-presence of anionic polymers (some acrylates/carbomers, anionic thickeners) can cause complexation and instability (opalescence, flocculation, viscosity loss). When needed, choose more compatible rheology systems or manage via controlled charge balance and disciplined addition sequence.

• Electrolytes and rheology profile. Salt and ionic strength affect both surfactant viscosity building and the structure of polymer complexes. Good practice is to map stability and sensoriality across realistic temperature and salinity ranges (including hard-water effects).

• Synergy with silicones. In 2-in-1 shampoos, PQ-67 is often used to increase silicone deposition efficiency: this can improve payoff, but it must be balanced to avoid heaviness on fine hair (which depends on the combined “silicone + deposition” system more than on the polymer alone).

Use guidelines (indicative)

Quality, grades, and specifications

Safety, regulatory, and environment

In cosmetics, Polyquaternium-67 is used as a functional polymer with safety assessment based on the finished product (use scenario, concentration, frequency, target population). The most common practical issues are not systemic toxicity but sensorial/formulation effects: excessive depositability (residue), possible non-specific irritation in sensitive users if the overall formula is harsh, and exposure management for spray products (where design should minimize respirable particulate and sticky residues).

From an environmental perspective, as with many cationic polymers, industrial attention focuses on effluent management and reducing concentrated releases during manufacturing rather than on diluted domestic rinse-off use. In manufacturing, applying GMP (Good manufacturing practice; first occurrence) improves control and repeatability; benefit: lower variability and improved quality robustness. Where relevant as a control approach, HACCP (Hazard analysis and critical control points; first occurrence) supports proactive identification of sensitive points; benefit: preventive management of process and quality risks.

Formulation troubleshooting

Conclusion

Polyquaternium-67 is a cellulosic cationic conditioner designed to deliver combability, anti-static performance, and premium sensoriality in shampoos and cleansing systems, with a good fit for clear formulations and a useful role as a deposition aid (especially for silicones). Formulation success depends on controlling the clarity window, managing interactions with electrolytes and anionic polymers, and tuning depositability to hair type and product positioning.

Mini-glossary

INCI: standard nomenclature for cosmetic ingredient labeling.
Substantivity: ability of an ingredient to adhere/deposit onto a surface (e.g., hair) during use.
Coacervate: polymer/complex-rich phase that may form during dilution and can promote deposition on hair.
Film forming: ability to form a surface film, influencing slip and sensoriality.
GMP: Good manufacturing practice; benefit: reduces variability and improves quality control.
HACCP: Hazard analysis and critical control points; benefit: supports prevention at critical process/quality points.