Trimethylpentanediol …
INCI: TRIMETHYLPENTANEDIOL/ADIPIC ACID/GLYCERIN CROSSPOLYMER
Reviewed by Kate · Last updated 2 Jun 2026
A synthetic humectant and conditioning agent that helps skin retain moisture
Best For Skin Types
All, Dry, Sensitive
Addresses
Usage Frequency
Daily
What Is Trimethylpentanediol …?
Trimethylpentanediol/Adipic Acid/Glycerin Crosspolymer is a synthetic polymer created by linking trimethylpentanediol (a humectant), adipic acid, and glycerin together. It functions as a skin conditioning agent designed to improve the feel and hydration of skincare formulations.
This ingredient is used in relatively small concentrations across a modest range of skincare products. Its primary role is to support the skin's moisture retention and to enhance product texture and spreadability.
How It Works
This crosspolymer works by attracting and binding water to the skin's surface through its humectant components (glycerin and trimethylpentanediol). This hygroscopic effect draws moisture from the environment and deeper skin layers, helping to keep the outer layer hydrated.
The polymer structure also allows the ingredient to form a light conditioning film on skin, which can help reduce transepidermal water loss and contribute to a smoother skin feel.
Clinical Evidence & References
Published clinical data specifically examining this crosspolymer in isolation is limited. The evidence base relies largely on the known properties of its individual components—glycerin and trimethylpentanediol are well-established humectants with demonstrated hydrating effects—combined with industry experience of similar polymer conditioning agents.
It is generally recognised as safe in cosmetic use, though robust comparative efficacy studies are sparse. Its inclusion in formulations suggests manufacturers have found it useful for texture and hydration support, but claims should be assessed within the context of the full product formula.
How to Use
This ingredient is typically found at low concentrations within complete skincare formulations rather than as a standalone product. Use the formula as directed by the manufacturer. If layering products, allow each to absorb before applying the next, and monitor your skin's response over a few weeks to assess any benefit.
Safety & Precautions
Frequently Asked Questions
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