Structure–Performance Relationship of Polyquaterniums in Hair and Personal Care Formulations: Smoothing Conditioning, Antistatic Performance, Film Formation, and Deposition Behavior

1 Polyquaterniums Are a Class of Functional Polymers

Polyquaterniums are commonly listed in cosmetic ingredient declarations in the form of “Polyquaternium-number,” such as Polyquaternium-7, Polyquaternium-10, Polyquaternium-22, Polyquaternium-37, and Polyquaternium-55. In the industry, PQ is often used as the abbreviation for Polyquaternium.

The common structural feature of polyquaterniums is the presence of quaternary ammonium cationic groups in the molecular structure. These quaternary ammonium groups carry permanent positive charges, allowing such polymers to interact with negatively charged sites on the surface of hair keratin, in the stratum corneum of the skin, or with other charged components in a formulation. After adsorption, the polymer chains can form a conditioning film on the surface, thereby changing surface friction, charge status, combability, foam texture, film-forming properties, and the overall sensory feel during use.

Different numbers after “Polyquaternium” represent different INCI names, where INCI stands for International Nomenclature Cosmetic Ingredient. Behind these different names may be completely different polymer structures. For example:

① Polyquaternium-7 is a cationic copolymer of acrylamide and DADMAC, or diallyldimethylammonium chloride.

② Polyquaternium-10 is a cationically modified hydroxyethylcellulose-type polymer.

③ Polyquaternium-22 is a copolymer of acrylic acid and DADMAC.

④ Polyquaternium-37 is a cationic acrylic polymer commonly used for conditioning and rheology modification.

⑤ Polyquaternium-55 is more oriented toward film formation, styling hold, and humidity resistance.

In the household and personal care industry, M550 is a commonly encountered trade name or industry shorthand for PQ-7-type aqueous cationic copolymers.

2 Why Polyquaterniums Improve Smoothness, Antistatic Performance, and Combability

2.1 The Negative Charge Characteristics of the Hair Surface Are the Starting Point of Their Function

The hair surface is mainly composed of keratin and lipid structures. After cleansing, combing, dyeing, perming, heat treatment, ultraviolet exposure, or mechanical friction, the hair cuticle can become damaged, surface roughness increases, and negatively charged sites on the surface may also increase. An increase in negative charge can lead to the following effects:

① Hair fibers are more likely to repel one another due to static electricity.

② Friction increases in damaged cuticle areas.

③ Wet combing resistance increases.

④ Dry hair becomes more prone to frizz, flyaway, puffiness, and tangling.

⑤ Gloss and smoothness decrease.

The quaternary ammonium cationic groups in polyquaterniums can undergo electrostatic adsorption with these negatively charged sites. In general, the more severely damaged the hair surface is, the more readily it tends to adsorb cationic conditioning polymers. Therefore, many shampoos, conditioners, and hair masks use polyquaterniums to improve wet combing, dry combing, and frizz control for damaged hair.

2.2 Smoothness Comes from “Friction Reduction After Adsorption”

After polyquaterniums adsorb onto the hair surface, the factor that truly affects the user experience is the adsorbed polymer layer. This polymer conditioning film can:

① Cover some rough areas.

② Reduce friction between hair fibers.

③ Improve wet combing resistance.

④ Reduce static electricity in dry hair.

⑤ Enhance the slip and softness of the hair surface.

⑥ In some systems, help silicones, oils, or other conditioning ingredients deposit onto the hair.

Even a small amount of polyquaternium in a shampoo may significantly change the feel of wet hair. It does not restore the internal structure of hair to an undamaged state. Instead, through surface adsorption and film formation, it improves the frictional condition of the damaged hair surface.

2.3 Antistatic Performance Comes from “Charge Neutralization and Surface Shielding”

When the negative charge on the hair surface increases, hair fibers tend to repel one another, resulting in flyaway, frizz, and poor manageability. Polyquaterniums carry positive charges and can partially neutralize the negative charges on the hair surface, reducing static charge accumulation. At the same time, the polymer film can provide a certain shielding effect on the hair surface, reducing friction and charge exchange between hair fibers. The more pronounced the antistatic effect, the easier dry hair usually is to comb, and the lower the perceived frizz.

2.4 Conditioning Performance Comes from Appropriate Deposition

In hair and personal care formulations, deposition refers to the process by which conditioning ingredients transfer from the formulation system and remain on the surface of hair or skin during use and rinsing. For polyquaterniums, deposition mainly comes from adsorption between quaternary ammonium cationic groups and negatively charged sites on the hair surface. It may also come from polymer–surfactant complexes or coacervate phases formed between polyquaterniums and anionic surfactants, which deposit during rinsing.

Appropriate deposition is an important basis for polyquaterniums to deliver conditioning benefits. During shampooing or conditioning, polyquaterniums can reduce friction on the hair surface through cationic adsorption and polymer film formation. After rinsing, an appropriate amount of polymer or conditioning complex retained on the hair surface can continue to improve wet combing, dry combing, antistatic performance, smoothness, and frizz control. However, more deposition is not always better. When the cationic charge density is high, the molecular weight is large, the dosage is excessive, or the polymer forms strong complexes with anionic surfactants, the conditioning film on the hair surface may become too thick. This may result in heavy hair feel, reduced volume, an overly strong film sensation after rinsing, or an unnatural slippery feel.

If the formulation also contains silicones, cationic surfactants, fatty alcohols, or relatively high levels of oils, polyquaterniums may also produce synergistic deposition with these conditioning ingredients. Synergistic deposition helps improve softness, gloss, and dry combing performance. However, in formulations for fine hair, oily scalp, or refreshing-type shampoos, it may also increase heaviness and cumulative buildup after long-term use.

3 Structure Determines Performance: Five Variables to Consider When Selecting Polyquaterniums

3.1 Cationic Charge Density: Determines Adsorption Strength

Cationic charge density refers to the number and distribution of positively charged groups along the polymer chain. It directly affects the affinity of the polymer for hair, the stratum corneum of the skin, and negatively charged components in the formulation.

Cationic charge density	Potential performance benefits	Points requiring attention
Low	Lighter conditioning feel, cleaner rinse feel, lower risk of residue	May provide insufficient improvement in wet combing for severely damaged hair
Medium	Easier to balance smoothness, antistatic performance, wet combing, and volume	Dosage needs to be adjusted according to the surfactant system and hair type
High	Stronger adsorption, more obvious conditioning feel, more helpful for damaged hair	May cause heaviness, limp hair, reduced transparency, or increased residue feel

Cationic charge density determines whether the polymer can effectively adsorb onto the hair surface, and it also determines whether deposition is likely to become excessive. Shampoos for fine hair and oily scalp usually should not pursue overly strong deposition. For damaged, dyed, permed, or coarse hair, conditioning deposition can be appropriately increased, but heaviness and residue still need to be controlled.

3.2 Molecular Weight: Determines Film Feel, Film Thickness, and Thickening Contribution

Polyquaterniums are polymers, so molecular weight has a significant effect on performance. In general, when the molecular weight is higher, polymer chains are more likely to form continuous or semi-continuous films, bringing a more obvious film feel, smoother feel, and thickening contribution. When the molecular weight is lower, the system usually feels lighter, but the support for film formation and conditioning may be weaker.

In shampoos, molecular weight also affects foam texture and rinse feel. An appropriate polymer structure can make the foam finer and denser. However, if the polymer is not properly matched with the surfactant system, it may also affect foaming speed, foam freshness, or transparency.

3.3 Polymer Backbone: Determines the Main Functional Direction

The polymer backbone determines which type of function a polyquaternium is more inclined to provide.

Structural type	Representative ingredients	Main characteristics	Suitable applications
Acrylamide/DADMAC copolymers	PQ-7/M550	Aqueous cationic copolymers, commonly used in cleansing systems	Light conditioning, wet combing, foam texture, and post-rinse softness in shampoos, body washes, and hand washes
Cationic celluloses	PQ-10, PQ-67	Good water solubility; provide conditioning, film formation, antistatic effects, and some thickening	Wet combing in shampoos, smoothness in conditioners, and conditioning in transparent systems
Acrylic acid/DADMAC or acrylic copolymers	PQ-22, PQ-39	Provide charge regulation, film formation, conditioning, and formulation compatibility	Shampoos, hair care products, cleansing products, and some styling products
Cationic acrylic homopolymers	PQ-37	Often used in dispersion form, with strong conditioning and rheology modification capabilities	Thickening, suspension, and sensory modification in conditioners, creams, sunscreens, and cream-based systems
Film-forming styling polymers	PQ-11, PQ-55	Place greater emphasis on film formation, styling hold, humidity resistance, and flexibility	Hair sprays, mousses, gels, leave-in care products, and anti-frizz styling products

3.4 Hydrophilic/Hydrophobic Characteristics: Determine Freshness, Deposition, and Formulation Compatibility

Polyquaterniums differ not only in charge properties but also in hydrophilicity and hydrophobicity. Polyquaterniums with stronger hydrophilicity are more readily incorporated into aqueous systems and are suitable for shampoos, body washes, hand washes, and transparent products. They usually provide wet combing, a soft and slippery feel, and antistatic performance, while also being easier to disperse and process.

Polyquaterniums with hydrophobic modification or film-forming characteristics may be more favorable for deposition on the hair surface, humidity resistance, styling hold, flexible film formation, or synergy with oily conditioning ingredients. However, these structures also require greater attention to transparency, fresh feel, flaking, tackiness, and cumulative buildup after long-term use.

3.5 System Compatibility: Determines Whether the Polymer Can Truly Perform in the Final Formulation

The final performance of a polyquaternium is not determined only by the raw material itself, but also by the entire formulation system. In shampoos and body washes, it needs to coexist with anionic surfactants, amphoteric surfactants, nonionic surfactants, electrolytes, thickeners, preservatives, fragrances, and oil-based ingredients. Cationic polymers and anionic surfactants may form complexes. Moderate complexation is beneficial for deposition during rinsing, while overly strong complexation may lead to turbidity, precipitation, reduced foam, or a poorer rinse feel.

4 Functional Classification of Common Polyquaterniums

The key difference among common PQ ingredients lies in the formulation problems they are designed to solve. When selecting a polyquaternium, one should first determine whether the formulation needs light conditioning in a cleansing system, smoothness improvement on the hair surface, rheology support for formulation structure, or film-forming hold in leave-on products.

Functional classification	Representative ingredients	Main problems addressed	Key validation points
Light conditioning type for cleansing systems	PQ-7/M550, PQ-22, PQ-39, PQ-44, and some PQ-10	Balances compatibility, foam, wet combing, and light feel in cleansing systems	Transparency, foam, wet combing, rinse feel, and dry-hair volume
Surface conditioning and wet combing improvement type	PQ-10, PQ-67	Reduces friction on the hair surface through cationic adsorption and polymer film formation	Wet combing resistance, dry combing smoothness, risk of heaviness, and long-term buildup
Rheology and sensory multifunctional type	PQ-37, PQ-39	Affects conditioning, viscosity, suspension, spreadability, and the body of cream systems	Supply form, addition method, shear conditions, and system stability
Film-forming styling type	PQ-11, PQ-55	Provides styling support, humidity resistance, and flexible film feel through film formation	Style retention, humidity resistance, flaking, tackiness, and film flexibility

4.1 Light Conditioning Type for Cleansing Systems: Balancing Compatibility, Light Deposition, and Fresh Feel

Conditioning polymers represented by PQ-7/M550 for cleansing systems mainly function in anionic or amphoteric surfactant systems. They need to remain stable in the formulation without significantly compromising transparency or foam. At the same time, they should form appropriate conditioning deposition during use and rinsing to improve post-wash roughness, wet hair combing difficulty, insufficient foam fineness, and post-rinse tightness.

The conditioning strength of this type of polyquaternium should not be too heavy. If deposition is insufficient, post-wash smoothness and wet combing improvement will not be obvious. If deposition is too strong, the hair may feel heavy, the rinse feel may become less fresh, dry-hair volume may decrease, or system transparency may deteriorate. The value of PQ-7/M550 lies in balancing cleansing, foam, transparency, and light conditioning, rather than providing a heavy conditioning film.

4.2 Surface Conditioning and Wet Combing Improvement Type: Reducing Friction on the Hair Surface

PQ-10 and PQ-67 mainly act on the hair surface through cationic adsorption and polymer film formation. The surface of damaged hair is rough, friction increases, and negatively charged sites increase. After deposition, these polyquaterniums can reduce friction between hair fibers and improve wet combing, dry combing, antistatic performance, smoothness, and frizz control.

These ingredients improve the condition of the hair surface, including roughness, friction, charge, and sensory feel. They can improve the appearance and combability of damaged hair, but they are not equivalent to rebuilding the internal structure of the hair. In the formulation, deposition strength needs to be controlled so that hair is easy to comb when wet and smooth after drying, while avoiding heaviness in fine hair or cumulative buildup after long-term use.

4.3 Rheology and Sensory Multifunctional Type: Simultaneously Affecting Conditioning Performance and Formulation Structure

In addition to providing conditioning or film-forming effects, PQ-37 and PQ-39 also affect system viscosity, suspension stability, spreadability, cream body, and sensory feel during use. PQ-37 in particular may be supplied commercially in dispersion form, and its carrier, addition sequence, shear conditions, and system compatibility all affect the final appearance, viscosity, and stability of the formulation.

The value of this type of polyquaternium is not reflected only in smoothness. They are more suitable for formulations that need simultaneous adjustment of sensory feel, viscosity, and stability, such as conditioners, creams, sunscreens, and cream-based systems. If they are handled merely as ordinary water-soluble conditioning polymers, insufficient dispersion, abnormal viscosity, or reduced stability may occur.

4.4 Film-Forming Styling Type: Film Strength, Flexibility, and Humidity Resistance Determine Performance

PQ-11 and PQ-55 are mainly used in leave-on care and styling products. They form polymer films on the hair surface, providing styling support, humidity resistance, frizz control, and a certain flexible film feel. Their core performance comes from film quality rather than improvement of wet combing after rinsing.

Film-forming styling polyquaterniums and light conditioning polyquaterniums for cleansing systems have different functional targets. PQ-7/M550 and PQ-10 focus more on foam, wet combing, rinse feel, and dry-hair volume, while PQ-11 and PQ-55 focus more on style retention, humidity resistance, low tackiness, film flexibility, and whether flaking or film debris appears after combing. These two types of raw materials should not be replaced with each other at equal dosage simply because both belong to the Polyquaternium family.

5. Representative Chemical Classification Tables Related to the Structure–Performance Relationship of Polyquaterniums in Hair and Personal Care Formulations

Table 1 Polyquaterniums and Cationic Conditioning Polymers

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Film-forming conditioning polyquaternium	95144-24-4	L475431	Luviquat™ FC 550	Approx. 40% active content in H₂O	Polyquaternium-16-type cationic film-forming conditioning polymer, used for studies on hair styling, antistatic performance, flexible film feel, frizz control, and film-forming performance in formulations
Cationic acrylic polymer	26161-33-1	P486958	Homopolymer of N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]ethanaminium chloride	—	Polyquaternium-37-type cationic methacrylate polymer, used for studies on charge density, adsorption onto the hair surface, polymer deposition, film formation, and rheology modification
Light conditioning polyquaternium for cleansing systems	26590-05-6	P501288	Dimethyldiallylammonium chloride/acrylamide copolymer	10 wt. % in H₂O	Polyquaternium-7-type conditioning polymer, used for experiments on wet combing, antistatic performance, foam fineness, and light deposition in shampoo and body wash systems
High-charge-density cationic polymer	26062-79-3	P109720	Poly(diallyldimethylammonium chloride) (PDADMAC)	Mw 200,000–350,000, 20 wt. % in water, 250–500 cP at 25 °C	Cationic polymer electrolyte, used for experiments on charge neutralization on the hair surface, polymer adsorption, flocculation deposition, and comparison of cationic charge density
High-charge-density cationic polymer	26062-79-3	P298922	Poly(diallyldimethylammonium chloride) solution (PDADMAC)	20 wt. % aqueous solution, 600–900 cP at 25 °C	High-viscosity aqueous cationic polymer solution, used for studies on deposition amount, film feel, adsorption strength, and the influence on system viscosity
Cellulose-based conditioning polyquaternium	81859-24-7	P341830	Polyquaternium-10	Viscosity 300–500 mPa·s, 2% aqueous solution at 25 °C	Cationic cellulose polymer, used for experiments on wet combing, antistatic performance, smoothness, film formation, and thickening in hair and personal care systems
Film-forming conditioning polyquaternium	53633-54-8	P101212	Polyquaternium-11	20 wt. % in H₂O	Cationic film-forming conditioning polymer, used for studies on hair styling, leave-in care, antistatic performance, dry combing smoothness, and flexible film feel
Film-forming antistatic polyquaternium	131954-48-8	B278970	Polyquaternium-28	10 wt. % in H₂O	Aqueous solution of a cationic film-forming polymer, used for experiments on film formation, antistatic performance, smoothness, and formulation compatibility in hair care products
Film-forming antistatic polyquaternium	131954-48-8	B302382	Polyquaternium-28	20 wt. % in H₂O	Aqueous Polyquaternium-28 solution with high active content, used for experiments on film strength, conditioning deposition, viscosity contribution, and dosage gradients
Polymeric cationic polymer for ophthalmic preservation and materials research	75345-27-6	P343010	Polyquaternium-1	≥95%	Polymeric cationic antimicrobial and preservative research material, used for studies on ophthalmic preservation, surface adsorption, antimicrobial evaluation, and material surface modification

Table 2 Cationic Surfactants and Hair-Conditioning-Related Raw Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Long-chain cationic conditioning agent	17301-53-0	N587655	N,N,N-Trimethyldocosan-1-aminium chloride	≥80%	Long-chain quaternary ammonium conditioning agent, used for studies on antistatic performance, softness, dry combing improvement, and fatty alcohol lamellar structures in conditioners and hair mask systems
Long-chain cationic conditioning agent	112-03-8	S105314	Stearyltrimethylammonium chloride (STAC)	≥98%	Long-chain cationic surfactant, used for comparative experiments on hair conditioning, antistatic performance, surface adsorption, and cationic conditioning systems
Long-chain cationic conditioning agent	112-02-7	H105309	Cetyltrimethylammonium chloride (CTAC)	≥97%	Cationic conditioning surfactant, used for studies on wet combing, antistatic performance, softness, and synergistic deposition with polyquaterniums in hair care systems

Table 3 Monomers Related to Polyquaternium Synthesis, Structural Research, and Performance Evaluation

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Monomer related to cationic polymers	79-06-1	A108465	Acrylamide	AR, ≥99%	Water-soluble polymerization monomer, used for research on Polyquaternium-7-type copolymers, coacervate phases, deposition behavior, and polymer molecular structure
Anionic comonomer for copolymer regulation	79-10-7	A397753	Acrylic acid	Anhydrous grade, ≥99%, containing 200 ppm MEHQ inhibitor	Carboxyl-containing monomer, used for studies on amphoteric polymers, charge balance, polymer–surfactant complexation, and deposition control
Monomer related to cationic polymers	7398-69-8	D110133	Diallyldimethylammonium chloride (DADMAC)	60% in water	Quaternary ammonium cationic monomer, used for structural and charge-density studies of Polyquaternium-6, Polyquaternium-7, and related cationic copolymers
Cationic acrylic monomer	5039-78-1	M102201	Methacryloyloxyethyltrimethylammonium chloride	75 wt. % in H₂O, containing MEHQ inhibitor	Cationic methacrylate monomer, used for studies on cationic acrylic polymers, surface adsorption, film formation, and rheological properties

Note: The above products are representative Aladdin products related to scientific research and formulation studies. For more information on product specifications, grades, and COA details, please search by product name, CAS number, or catalog number on the Aladdin official website. The products listed in the tables are related to polyquaternium synthesis, structural research, and performance evaluation; they do not indicate direct applicability in finished cosmetic formulations. Actual application should be based on applicable regulations, SDS, COA, residual monomer control requirements, and specific intended use.

References

[1] Lubrizol. Merquat™ 550 Polymer, INCI Name: Polyquaternium-7.

[2] Lubrizol. Merquat™ 550PR Polymer, INCI Name: Polyquaternium-7.

[3] Cosmetic Ingredient Review. Final Report on the Safety Assessment of Polyquaternium-10. International Journal of Toxicology.

[4] Dow. UCARE™ Extreme Polymer, INCI Name: Polyquaternium-10.

[5] SpecialChem. Polyquaternium-22 INCI Ingredient Description.

[6] Ashland. Conditioneze™ 37 Polymer, INCI Name: Polyquaternium-37.

[7] Ashland. Styleze™ W-17 Polymer, INCI Name: Polyquaternium-55.

[8] Dow. SoftCAT™ Polymer SL-30, INCI Name: Polyquaternium-67.

[9] Guzmán E., et al. Physicochemical Aspects of the Performance of Hair-Conditioning Formulations. Cosmetics, 2020, 7(2), 26.

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