Introduction
Polyquaternium-7 is a staple ingredient in modern cosmetic chemistry, revered for its ability to provide exceptional conditioning without weighing hair down. Unlike heavier oils or waxes, this cationic copolymer delivers a “weightless” slip that is essential for detangling fine or oily hair types. It is widely used in shampoos, conditioners, and body washes to improve texture and sensory feel.
Chemically, Polyquaternium-7 is a copolymer of acrylamide and diallyldimethylammonium chloride. Its unique structure allows it to carry a high cationic (positive) charge density, which attracts it to the anionic (negative) charges found on damaged hair strands and skin. This electrostatic interaction smooths the cuticle, reduces static, and imparts a soft, velvety after-feel.
For formulators, Polyquaternium-7 offers a distinct advantage: superior compatibility with anionic surfactants. While many cationic polymers precipitate or “crash out” when mixed with standard sulfates or sulfonates, Polyquaternium-7 remains stable. Formula Chemistry provides practical formulation education and safety-forward guidance to help you master these interactions and create professional-grade products.
Quick Facts
- INCI Name: Polyquaternium-7
- Function: Antistatic Agent, Film Former, Hair Fixative, Skin Conditioning Agent
- Charge: Highly Cationic (Positive)
- Typical Usage Rate: 0.2% – 5.0% (Standard commercial concentration is usually roughly 8-10% solids)
- Solubility: Highly water-soluble; easily added to the aqueous phase.
- pH Stability: Stable across a wide range, typically pH 4.0 – 9.0.
- Compatibility: Excellent compatibility with anionic, nonionic, and amphoteric surfactants.
- Key Benefit: Reduces static electricity and improves wet combing without buildup.
- Safety Note: Generally safe for rinse-off products; ensure proper preservation in all water-based
What is Polyquaternium-7 and Why is it Effective?
Polyquaternium-7 is classified as a “polyquat,” a group of polycationic polymers used extensively in personal care. Its effectiveness results from its ability to form a clear, non-tacky film on the surface of hair and skin. This film seals in moisture and smooths rough surfaces, which physically reduces friction during combing or styling.
The “7” in its name does not refer to a chemical count but rather the numerical order in which the polymer was registered with the International Nomenclature of Cosmetic Ingredients (INCI). Despite the complex chemistry, its primary job is simple: to neutralize the negative charge of keratin. Damaged hair is negatively charged; by attaching to these sites, Polyquaternium-7 prevents “flyaways” and forms a cohesive, shiny appearance.
The Chemistry of Cationic Conditioning
Conditioning is essentially a game of opposites attracting. Healthy hair has a protective lipid layer, but environmental stressors, heat styling, and chemical treatments strip this layer, leaving the hair shaft porous and negatively charged. Polyquaternium-7 possesses positively charged sites along its polymer chain.
When applied, these positive sites bind ionically to the damaged, negative areas of the hair shaft. This process is called “substantivity.” Because Polyquaternium-7 is a high-molecular-weight polymer, it doesn’t just bind; it lays flat against the cuticle. This flattens the scales of the hair shaft, allowing a comb to glide through wet hair effortlessly, greatly reducing mechanical damage during detangling.
Benefits Beyond Hair: Skin and Foam Enhancement
While famous for hair care, Polyquaternium-7 is a secret weapon in skincare and body cleansing formulations. In body washes and shower gels, it provides a luxurious “slip” that makes the product feel more expensive and substantial. It reduces the “squeaky clean” or stripped feeling that harsh surfactants can leave on the skin, replacing it with a soft, conditioned finish.
Additionally, Polyquaternium-7 acts as a foam stabilizer. While it does not generate foam on its own, its polymeric structure strengthens the bubble walls created by your primary surfactants (like Sodium Lauryl Sulfate or Cocamidopropyl Betaine). This results in a creamier, denser lather that lasts longer during the wash, improving the overall consumer experience.
Formulating with Polyquaternium-7: Best Practices
Integrating Polyquaternium-7 into a formulation is generally simple due to its water solubility, but knowing the details of usage rates and phase addition secures optimal stability. It is typically sold as a viscous, clear liquid containing about 8–10% active polymer solids and preserved water.
Because it is liquid and water-soluble, it can often be added to the water phase at the beginning of the process or during the cool-down phase (below 40°C). However, adding it early allows it to fully hydrate and disperse before surfactants or thickeners are introduced. For cold-process formulations, it is an excellent choice as it requires no heating to activate.
Usage Rates and Compatibility
The effective usage rate depends heavily on the product type. For a standard daily shampoo, a range of 0.5% to 2.0% is usually sufficient to provide detangling without causing buildup. For a 2-in-1 conditioning shampoo or a rich body wash, you might increase this to 3.0%.
One of the most significant formulation benefits of Polyquaternium-7 is its anionic compatibility. Many cationic conditioners (like Cetrimonium Chloride) will form an insoluble complex when mixed with anionic surfactants, resulting in a cloudy, separated mess. Polyquaternium-7 does not typically have this issue. It can be formulated directly into clear, surfactant-based systems without calling for specialized suspension agents or stabilizers.
Table: Comparison of Common Cationic Polymers
| Feature | Polyquaternium-7 | Polyquaternium-10 | Guar Hydroxypropyltrimonium Chloride |
| Source | Synthetic (Copolymer) | Cellulose Derivative | Guar Gum Derivative |
| Charge Density | High | Low to Medium | Medium to High |
| Clarity | Crystal Clear | Can be Hazy | Often Cloudy/Opaque |
| Build-up Potential | Low (Lightweight) | Medium | Medium to High |
| Best Application | Clear Shampoos, Body Wash | Conditioners, Shampoos | Creamy Conditioners |
Stability and pH Considerations
Polyquaternium-7 is remarkably robust regarding pH. It remains stable and effective in formulations ranging from pH 4.0 to 9.0. This versatility permits it to be used in acidic conditioners (which seal the cuticle) as well as neutral or slightly alkaline cleansers.
However, formulators must be mindful of salt sensitivity. While Polyquaternium-7 is generally salt-tolerant, extremely high concentrations of Sodium Chloride (used for thickening surfactant systems) can occasionally interfere with the polymer’s solubility or clarity. It is best to add salt slowly and look for any haze formation. Additionally, consistently verify the compatibility of your preservative system, though Polyquaternium-7 rarely interferes with common preservatives like Phenoxyethanol or Sodium Benzoate.
Diagnosing Common Formulation Issues
Even with a sturdy ingredient like Polyquaternium-7, issues can arise, notably concerning texture and clarity. A common mistake beginners make is using too much, assuming “more is better” for conditioning. In reality, excess cationic polymer can leave hair feeling coated, sticky, or limp, especially on fine hair types.
Another regular issue is turbidity (cloudiness) in what should be a clear system. While Polyquaternium-7 is compatible with anionics, the order of addition or the specific ratio of surfactants can sometimes cause temporary haze. Making sure the polymer is fully diluted in the water phase before adding concentrated surfactants frequently resolves this.
Common Problems and Fixes
- Problem: The shampoo leaves a sticky or “coated” feeling on the hair.
- Fix: The usage rate is likely too high. Reduce Polyquaternium-7 to 0.5% – 1.0%. If the problem persists, ensure you are not combining it with other heavy silicones or gums.
- Problem: The formulation turned cloudy upon adding Polyquaternium-7.
- Fix: This can happen if added directly to highly active surfactants. Pre-mix the Polyquaternium-7 in the water phase first. If adding at the end, dilute it with a small amount of water before adding to the main batch.
- Problem: The body wash is too thin (viscosity loss).
- Fix: Polyquaternium-7 generally does not thicken. You may need to increase your salt (NaCl) concentration or add a dedicated rheology modifier like PEG-150 Distearate or Crothix.
- Problem: Reduced foam volume.
- Fix: While it stabilizes foam, high levels of any oil or polymer can depress lather generation. Balance the formula by slightly increasing the secondary surfactant (like Cocamidopropyl Betaine).
Preventing Build-up and Irritation
Although Polyquaternium-7 is considered “low buildup” compared to Guar derivatives, it is effectively a plastic-like film former. Continuous use without proper cleansing can eventually lead to accumulation. It is vital to advise users or market the product appropriately clarifying that shampoos effectively remove this polymer.
From a safety perspective, Polyquaternium-7 may contain trace amounts of acrylamide monomer (a byproduct of manufacturing). Reliable suppliers ensure the residual acrylamide content is extremely low (< 1-5 ppm) to meet safety regulations. Always source from trusted cosmetic suppliers who provide a Certificate of Analysis (CoA) verifying purity. Do not use industrial-grade polymers for personal care applications.
FAQ’s about Polyquaternium-7: A Lightweight Conditioner for Smooth Hair
Is Polyquaternium-7 a silicone?
No, Polyquaternium-7 is not a silicone. It is a cationic polymer (plastic-like molecule). While it performs a similar function to silicones—smoothing and detangling—it is water-soluble and chemically distinct. It is a popular alternative in “silicone-free” formulations.
Can Polyquaternium-7 be used in leave-in conditioners?
Yes, it can be used in leave-in products, but it must be used at very low rates (typically 0.2% – 0.5%). Because it forms a film, using too much in a product that isn’t rinsed off can make hair feel stiff, crunchy, or tacky.
Is Polyquaternium-7 natural?
No, Polyquaternium-7 is a synthetic ingredient. It is created through the polymerization of acrylamide and diallyldimethylammonium chloride. While not natural, it is biodegradable to an extent and is considered safe and effective for cosmetic use.
Does Polyquaternium-7 cause hair loss?
There is no scientific evidence suggesting Polyquaternium-7 causes hair loss. It acts superficially on the hair shaft and does not penetrate the follicle. However, excessive buildup on the scalp from poor cleansing could theoretically clog pores, pointing out the need for proper washing.
What is the difference between Polyquaternium-7 and Polyquaternium-10?
Polyquaternium-7 is synthetic, has a higher charge density, and is generally better for clarity and anionic compatibility. Polyquaternium-10 is derived from cellulose (wood pulp/cotton), offers more “natural” marketing, but can be harder to keep clear and may build up more easily.
Can I heat Polyquaternium-7?
Yes, Polyquaternium-7 is heat-stable and can be added to the heated water phase of a formulation (up to 80°C) without losing efficacy. This makes it flexible for emulsions that require melting waxes or butters.
Is Polyquaternium-7 compatible with sulfates?
Yes, this is one of its strongest features. Unlike many cationic conditioners that clump when mixed with Sodium Lauryl Sulfate (SLS) or Sodium Laureth Sulfate (SLES), Polyquaternium-7 remains clear and stable, making it ideal for standard shampoos.
Is Polyquaternium-7 biodegradable?
Polyquaternium-7 is not readily biodegradable in the traditional sense, which is a concern for some eco-conscious brands. However, it is removed effectively by wastewater treatment plants. Formulators seeking strictly biodegradable options often opt for Guar Hydroxypropyltrimonium Chloride instead.
