Cosmetic formulations typically rely on multiple ingredients working together to meet different product needs. Polyols are a good example. Glycerin, butylene glycol, pentanediol, and other polyols have distinct molecular structures that enable them to play different roles in moisturization, as solvents, and in supporting formulation protection.
Among these, 1,2-pentanediol (INCI name: Pentylene Glycol) is a versatile cosmetic ingredient. As a small-molecule diol, clues to its diverse applications can be found in its molecular structure.
01 | Structure Shapes Properties
1,2-Pentanediol consists of a carbon chain of five carbon atoms and two adjacent hydroxyl groups (-OH), and belongs to the class of 1,2-alkanediols.
In 1,2-pentanediol, the two hydroxyl groups are adjacent to one another at one end of the carbon chain, while the remaining hydrocarbon portion is relatively hydrophobic. The presence of both hydrophilic groups and a relatively hydrophobic chain gives 1,2-pentanediol a degree of amphiphilic character, influencing how it interacts with water and other formulation components.
02 | From Properties to Applications: Moisturization, Solvency, and Formulation Protection
These physicochemical properties give 1,2-pentanediol several useful functions in cosmetic formulations.
(1) Moisturization: Hydrogen Bonding and Stratum Corneum Hydration
The hydration level of the stratum corneum is closely linked to moisture retention and skin barrier function, making it an important consideration in moisturizing formulation design (Rawlings & Harding, 2004). As classic humectants, small-molecule polyols can absorb and retain moisture through their hydrophilic groups, helping to maintain the hydration of the stratum corneum. (Fluhr et al., 2008).
The hydroxyl groups in 1,2-pentanediol can form hydrogen bonds with water molecules, which play an important role in its interactions with water. In addition, the positions of the hydroxyl groups and the carbon-chain structure further influence diol–water interactions, affecting water-binding behavior and the state of water within the formulation (Kerdudo et al., 2015).In other words, it does not merely "bind" water molecules; it also helps regulate the state of water in the formulation.*
Figure: Hydrogen bonding with a water molecule, illustrated using one hydroxyl group as an example.
(2) Solvent Function: The Combined Influence of Polar and Nonpolar Structures
Some cosmetic ingredients have limited water solubility and require suitable solvents to help disperse or incorporate them into a formulation. In 1,2-pentanediol, the hydroxyl groups can interact with water, while the carbon chain influences its interactions with organic components. Together, these structural features contribute to its polarity and a degree of lipophilicity, allowing it to function as a solvent and help improve the dissolution of certain ingredients (Johnson et al., 2012).*
(3) Formulation Preservative Assistance : An Additional Role of Its Molecular Properties
For water-based cosmetics, microbial control is a critical aspect of product quality management. A study on nonionic hydrophilic creams found that formulations containing 1,2-pentanediol exhibited antimicrobial activity against a variety of test microorganisms in microbial protection efficacy tests. (Sigg & Daniels, 2020)*
These three roles-moisturization, solvency, and formulation protection-must all be underpinned by a sound safety profile. An assessment by the Cosmetic Ingredient Review (CIR) provides safety support for the use of 1,2-pentanediol in cosmetics (Johnson et al., 2012). In formulation practice, the typical addition level is approximately 1%–5%, subject to validation in the specific formulation.
* The applications in moisturization, solvency, and formulation protection described above are based on the molecular properties of 1,2-pentanediol and relevant research. Actual performance depends on factors such as concentration, formulation composition, and conditions of use. Taking into account the properties of the target ingredients and the overall formulation design, performance should be verified through appropriate product efficacy assessments and microbial challenge testing.
The molecular structure explains the various roles that 1,2-pentanediol plays in formulations, and its different sources of raw materials also provide more options for its production.
YINO Biologic develops bio-based 1,2-pentanediol from corncobs, offering the personal care industry an ingredient option derived from a renewable feedstock.
• Bio-based origin: Derived from corncobs, with its bio-based content verified through USDA Certified Biobased Product certification.
• Cosmetic-grade specifications: Developed with the application needs of the personal care industry in mind.
• Quality data support: The product carbon footprint has been calculated in accordance with ISO 14067, and relevant parameters, including microbiological indicators and heavy metals, have been tested. These data provide a reference for customers evaluating ingredient quality.
References:
[1] Rawlings, A. V., & Harding, C. R. (2004). Moisturization and Skin Barrier Function. Dermatologic Therapy, 17(S1), 43–48.
[2] Kerdudo, A., Fontaine-Vive, F., Dingas, A., Faure, C., & Fernandez, X. (2015). Optimization of Cosmetic Preservation: Water Activity Reduction. International Journal of Cosmetic Science, 37(1), 31–40.
[3] Johnson, W. Jr., et al. (2012). Safety Assessment of 1,2-Glycols as Used in Cosmetics. International Journal of Toxicology, 31(5 Suppl), 147S–168S.
[4] Sigg, M., & Daniels, R. (2020). Investigations on Alkanediols as Alternative Preservatives in a Nonionic Hydrophilic Cream. Pharmaceutics, 12(11), 1117.
