In the world of cosmetic formulation, polymers play a key role: they are responsible for providing texture, stability, sensorial experience, and rheological behavior to products. But what exactly are they, and how do they influence a formula?

 

What Is a Polymer and Why Is It Used in Cosmetics?

A polymer is a macromolecule made up of smaller units called monomers, which are linked together in a process known as polymerization. They can be natural (such as xanthan gum or collagen) or synthetic (like acrylates or silicone derivatives), and their chemical structure defines properties such as viscosity, elasticity, adherence, and resistance to aging.

One important feature of polymers is their molecular weight distribution, which directly affects the final product's behavior—from its flowability to how it feels on the skin.
 

Types of Polymers in Cosmetic Formulation

In cosmetics, INCI names for polymers are often linked to their monomer components. There are several types:
  • Homopolymers: Made from a single type of monomer (e.g., Polypropylene Terephthalate).
  • Copolymers: Combine at least two different monomers (e.g., Acrylates/Stearyl Acrylate/Ethylamine Oxide Copolymer).
  • Crosspolymers: Include links between chains using multifunctional monomers acting as crosslinkers (e.g., Sodium Acryloyldimethyl Taurate/VP Crosspolymer).
  • Polygeneric Polymers: Formulated with four or more different monomers (e.g., Polyacrylate Crosspolymer-11).
  • Alkoxylated Homopolymer Ethers: Include ethylene oxide or propylene oxide compounds (e.g., PEG-16).
  • Derived Natural Polymers: Such as plant-based gums, proteins, or polysaccharides (e.g., Guar Gum, Xanthan Gum).
  • Silicone Derivatives: Widely used for their silky sensoriality and controlled volatility (e.g., Caprylyl Trimethicone).
 

How Does Polymer Structure Affect a Formula?

Choosing and combining monomers is essential to define a polymer’s behavior in a formulation. This impacts key parameters such as:
  • Rheology (flow and behavior under stress)
  • Electrolyte compatibility
  • Sensoriality
  • Surfactant compatibility
  • Stability across different pH levels
  • Final product viscosity

Every cosmetic formula has its own rheological behavior, determined by the ingredients and how they are combined. This behavior is analyzed under different shear rates and application times, with viscosity being the most commonly evaluated parameter.
 

What Are Rheology Modifiers and Why Are They Crucial in Cosmetic Formulations?

Rheology modifiers are ingredients specifically designed to adjust the texture, stability, and behavior of a cosmetic formula. This is essential for ensuring that a cream isn’t too runny, that a gel glides smoothly, or that an emulsion remains stable over time.
 

Benefits of Rheology Modifiers

  • Increase and control viscosity
  • Improve product texture
  • Enhance sensorial feel upon application
  • Stabilize emulsions and suspend particles
  • Improve visual appearance and spreadability
  • Easy to incorporate and highly versatile
 

Common Applications

  • Aqueous gels (cleansers, serums)
  • Hydroalcoholic gels (sanitizers, lightweight products)
  • Cream gels
  • O/W emulsions (moisturizers, sunscreens)
 

Key Characteristics

  • Often available as pre-neutralized powders
  • Act as effective thickeners
  • Stable over a wide pH range
  • Aid in particle stabilization
  • Enhance consistency and formula durability
 

Conclusion

Understanding the role of polymers and rheology modifiers enables the creation of more stable, appealing, and effective cosmetic products. From texture to long-term stability, these ingredients are essential to develop products that not only work well but also delight users.

If you’re a formulator, R&D technician, or simply passionate about the science behind cosmetics, mastering these concepts will bring you closer to developing high-performance, value-added products.

Want to learn more about innovative raw materials for cosmetics? Follow our blog and stay up to date with the latest ingredient trends and formulation strategies.

Looking for functional ingredients to improve your formulas’ rheology? Contact us at LEMMEL.