What Is Carbomer?
Carbomer is a generic term referring to high-molecular-weight crosslinked poly(acrylic acid) (PAA) polymers that are produced by the polymerization of acrylic acid with crosslinking agents like allyl pentaerythritol and allyl sucrose. The polymer structure features numerous carboxylic acid (-COOH) groups extending through its backbone which accounts for 52–68% of its composition and gives the material weak acidic characteristics along with pH-responsive behavior. The neutralization with bases causes the carboxylate groups to ionize which leads to significant chain expansion from electrostatic repulsion and hydration that creates transparent and stable hydrogels.
Fig.1 Unit structure and molecular formula of carbomer[1].
Carbomer is not a single compound but a class of polymers with varying molecular weights, particle sizes, and crosslinking densities. Its general repeating unit is based on acrylic acid: The properties of the polymer (C3H4O2)n depend on both the degree of polymerization n and the specific crosslinker used.
Alfa Chemistry provides an extensive assortment of Carbomer grades for use across pharmaceuticals, cosmetics, and materials engineering applications.
Representative Products of Carbomer
| Product Name | Appearance | Application | Price |
| Carbomer 940 | White powder | Clear gels, Hydroalcholic gels, Creams | Inquiry |
| Carbomer 980 | White powder | Clear gels, Hydroalcholic gels, Creams, Lotions | Inquiry |
| Carbomer U20 | White powder | Shampoos, Body washes, Gels, Lotions, Creams | Inquiry |
| Carbomer U21 | White powder | Clear gels, Hydroalcholic gels, Creams, Lotions | Inquiry |
How Do Carbomer Grades Differ and What Are Their Key Applications?
Various grades of Carbomer exhibit distinct rheological profiles and application suitability. The following table summarizes the most widely used types:
| Carbomer Grade | Viscosity (mPa·s) | Application Examples |
| Carbopol 934 | 30,500–39,400 | Ophthalmic gels, topical creams |
| Carbopol 940 | 40,000–60,000 | Hand sanitizers, gels with high viscosity |
| Carbopol 941 | 4,000–11,000 | Lotions and emulsions |
| Carbopol 980 | 40,000–60,000 | Transparent gels, styling products |
| Carbopol 974P | ~29,400 | Bioadhesive vaginal gels, spermicidal agents |
Each grade is selected based on viscosity, clarity, bioadhesion, and compatibility with other formulation components.
How Does Carbomer Contribute to Formulation Science Through Its Functional Properties?
- Thickening Efficiency
Carbomer has remarkable thickening properties when used at low concentrations between 0.1% and 1.0% w/w. The neutralized polymer turns into a highly viscous gel through swelling and chain entanglement which makes it suitable for creating gels, emulsions, and creams with customized rheological properties.
- Suspending Agent
Carbomer stabilizes suspended insoluble particles in low-surfactant systems due to its yield stress behavior, preventing sedimentation. This is particularly critical in oral suspensions, ophthalmic drops, and cosmetic formulations with pigment or active agents.
- Emulsion Stabilizer
In oil-in-water emulsions Carbomer works as a co-emulsifier which increases continuous phase viscosity and decreases dispersed droplet movement leading to improved long-term stability and better sensory properties.
- pH-Responsive Behavior
The swelling and sol-gel transitions of Carbomer show high dependency on pH levels. At acidic pH levels Carbomer stays un-ionized and compact but expands considerably when the pH reaches neutral levels between 5.5 and 7.5 to create optically clear gels. In situ gelling drug delivery systems like nasal and ocular formulations depend on this feature.
- Bioadhesion
Due to its high molecular weight and carboxyl content, Carbomer demonstrates strong bioadhesive properties on mucosal surfaces, enhancing drug residence time and absorption in vaginal, nasal, ocular, and buccal drug delivery applications.
How Is Carbomer Used in Pharmaceutical Applications?
Controlled Release Systems
Carbomer serves as a matrix former in sustained-release tablets. Its hydration and swelling create a gel barrier that controls the diffusion of active pharmaceutical ingredients (APIs), prolonging therapeutic effect. Drugs such as ascorbic acid and aspirin have been successfully formulated using Carbomer matrices.
Fig.2 Preparation and in vitro evaluation of carbomer-based hydrogels for controlling the release rate of diclofenac sodium[2].
Nasal and Ocular Gels
Carbomer 934-based pH-responsive in situ gels achieve both increased mucosal retention and enhanced permeability. A gel formulation for nasal delivery of buspirone hydrochloride transitions quickly at nasal pH (~6.4) to deliver enhanced retention and improved drug flux up to 83.49%. Ocular Carbopol gels deliver improved drug bioavailability while allowing patients to take medication less often.
Fig.3 Carbomer-based gelling system for nasal drug delivery[3][4].
Bioadhesive Vaginal Gels
Carbomer 974P is the principal polymer in BufferGel, a vaginal microbicide and contraceptive formulation[6]. It maintains an acidic pH (~3.9), essential for inactivating sperm and pathogens such as HIV. Its high water content (~94%) and strong gel structure make it ideal for mucosal delivery.
Suspensions and Topical Vehicles
Carbomer ensures uniform distribution of APIs in both oral and topical suspensions while keeping them homogeneous throughout their shelf life. In dermatological creams and transdermal gels Carbomer acts as a base material which promotes rapid drug release when applied.
Fig.4 April 2020 Labeling information for selected commercially available hand sanitizers in Italy[5].
How Does Carbomer Perform in Cosmetic and Personal Care Formulations?
Cosmetic and personal care products such as creams, lotions, serums, and shampoos commonly use Carbomer as a rheological modifier. It delivers luxurious textures while maintaining excellent clarity and stabilizing active ingredients. Carbomer 940 provides hand sanitizers with thick consistency alongside non-drip properties and compatibility with ethanol. For skin care emulsions, Carbomer stabilizes oil droplets and enhances spreadability, improving consumer acceptability.
Moreover, Carbomer is hypoallergenic, non-comedogenic, and shows minimal irritation potential. It undergoes stringent toxicological evaluations and is approved by global regulatory bodies for cosmetic and OTC pharmaceutical use.
FAQs About Carbomer
1. What is the recommended method for dispersing Carbomer in water without forming clumps?
To avoid clumping, Carbomer should be added slowly into vigorously stirred deionized or purified water. High shear mixers or overhead stirrers are recommended. Pre-wetting with a water-miscible non-solvent such as ethanol or glycerol can also improve dispersion uniformity.
2. How should Carbomer be neutralized to form a stable gel?
Carbomer requires neutralization with a suitable base to initiate gel formation. Common neutralizers include sodium hydroxide, triethanolamine (TEA), or aminomethyl propanol (AMP). The choice of neutralizer affects the clarity, viscosity, and final pH of the gel. Avoid using incompatible bases like potassium hydroxide if potassium ions may interfere with your formulation.
3. What are the storage and stability requirements for Carbomer raw materials?
Carbomer should be stored in a tightly sealed container, in a cool, dry place away from direct sunlight and moisture. The powder is hygroscopic and may degrade if exposed to high humidity. It is recommended to use Carbomer within 24 months of manufacture for optimal performance.
4. How does Carbomer perform under extreme pH or ionic strength conditions?
Carbomer is most effective in the pH range of 5 to 10. At extremely low pH (<4), the polymer remains coiled and does not fully swell. At high ionic strength or in the presence of multivalent cations (e.g., Ca2+ or Mg2+), gel structure may collapse due to ionic shielding of carboxylate groups.
5. Are there biodegradable alternatives to Carbomer for sustainable formulations?
Yes, several biodegradable rheology modifiers derived from polysaccharides (e.g., xanthan gum, alginates, cellulose derivatives) are available. However, they often lack the high clarity and viscosity control offered by Carbomer, requiring careful formulation adjustments.
6. Can Carbomer be sterilized for use in ophthalmic or parenteral formulations?
Yes, Carbomer-based gels can be sterilized using gamma irradiation or aseptic filtration post-formulation. Autoclaving is not recommended as high temperatures may degrade the polymer or alter its rheological properties.
7. How can Carbomer interact with APIs in formulation?
Carbomer may form hydrogen bonds or ionic interactions with cationic APIs, potentially affecting drug release or solubility. Compatibility studies are crucial, especially when developing sustained-release or mucoadhesive formulations.
8. Is Carbomer safe for inhalation or pulmonary drug delivery systems?
Carbomer is generally not recommended for pulmonary delivery due to the risk of respiratory tract irritation. However, low-dust grades or micronized versions may be considered if safety and deposition profiles are validated.
For more professional advice or high purity Carbomer products that comply with specific industry regulations, please contact Alfa Chemistry's professional technical team.
References
- Shi Y, et al. Fast detection of humidity sensor with a weakly coupled fiber coated with carbomer. Physica Scripta (2024).
- Suhail M, et al. Using Carbomer-Based Hydrogels for Control the Release Rate of Diclofenac Sodium: Preparation and In Vitro Evaluation. Pharmaceuticals (2020).
- Wang M, et al. The prescription design and key properties of nasal gel for CNS drug delivery: A review. European Journal of Pharmaceutical Sciences (2024).
- Viridén A, et al. The effect of chemical heterogeneity of HPMC on polymer release from matrix tablets. Eur. J. Pharm. Sci. (2009).
- Berardi A, et al. Hand sanitisers amid CoViD-19: A critical review of alcohol-based products on the market and formulation approaches to respond to increasing demand. International Journal of Pharmaceutics. (2020).
- Editor(s): J.K. Aronson. Physical contraceptives—spermicides. Meyler's Side Effects of Drugs: The International Encyclopedia of Adverse Drug Reactions and Interactions (Fifteenth Edition) (2006).
Please kindly note that our products are for research use only.
