What Is Methoxy Peg-100/Polyepsilon Caprolactone Ethylhexanoate?
Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate is a synthetic block copolymer created by linking two different molecules: a methoxy-terminated polyethylene glycol segment and a biodegradable polyester segment called polyepsilon caprolactone. The result is a flexible chain that blends water-loving and oil-loving parts, letting it interact nicely with both phases of a cosmetic formula.
This ingredient was developed in the early 2000s when formulators were looking for gentler film formers that could also condition hair. By tweaking the length of each block, chemists discovered they could adjust the softness, hold, and solubility of the finished polymer, making it useful in styling products and skin care.
Manufacturing starts with ring-opening polymerization of epsilon-caprolactone to build the polyester block. Separately, methoxy-terminated PEG-100 is prepared by polymerizing ethylene oxide to a set chain length. The two blocks are then coupled through an esterification step using ethylhexanoic acid, forming a stable yet biodegradable copolymer. Purification removes catalysts and by-products, yielding a waxy solid or viscous liquid ready for formulation.
You will most often spot Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate in hair gels, mousses, and spray fixatives, where it provides hold without stiffness. It also appears in leave-in conditioners, sheet masks, lightweight moisturizers, and primers that need a breathable film to lock in moisture or enhance wear.
Methoxy Peg-100/Polyepsilon Caprolactone Ethylhexanoate’s Cosmetic Benefits/Uses
This multifunctional polymer earns its place on an ingredient list by bringing several performance perks at once
- Buffering: Helps keep the product’s pH stable over time so the formula stays gentle on skin and hair
- Film Forming: Creates an invisible, flexible layer that reduces moisture loss, improves product wear, and adds a smooth feel
- Hair Conditioning: Coats strands lightly to enhance softness and shine while reducing static and frizz
- Hair Fixing: Provides light to medium hold, giving structure to styles without the crunchy texture linked to older styling resins
Who Can Use Methoxy Peg-100/Polyepsilon Caprolactone Ethylhexanoate
This ingredient is considered gentle enough for all skin types, including dry, normal, combination and oily. Its lightweight film allows moisture to escape naturally so it seldom feels heavy or occlusive even on breakout-prone skin. People with very sensitive or compromised skin should still check the full formula for fragrances or other potential irritants rather than the polymer itself, because it is rarely the culprit.
Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate is synthesized entirely from laboratory raw materials so no animal-derived inputs are used, making it suitable for vegans and vegetarians.
Current safety data do not flag any specific risks for women who are pregnant or breastfeeding. The molecule is too large to penetrate deeply and is not known to act as a hormone disruptor. This is not medical advice, and anyone expecting or nursing should review any new cosmetic with their healthcare provider to be on the safe side.
The polymer does not increase photosensitivity, so daylight exposure is not a concern. It is also odorless and colorless, which makes it unobtrusive in fragrance-free and dye-free formulations.
Potential Side Effects/Adverse Reactions
Reactions to topical Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate vary from person to person. The effects listed below are possible yet uncommon when the ingredient is used at typical levels in well-formulated products.
- Mild skin or scalp irritation such as transient redness or itching
- Rare allergic contact dermatitis for individuals sensitive to polyethylene glycol derivatives
- Product buildup on hair strands if used in high-hold styling products without adequate cleansing
- Temporary dullness or weight on very fine hair when over-applied
If you notice any discomfort stop using the product and consult a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1/5
Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate earns a low score because its large, water-soluble polymer chains do not sink into pores or mix with sebum in a way that would clog them. It forms a breathable, flexible film that sits on the surface then rinses away with normal cleansing. As a result, it is generally considered suitable for acne-prone or breakout-prone skin. Only extremely sensitive individuals who react to PEG derivatives might notice issues, but that is uncommon.
The ingredient is also typically used at modest levels in formulas that are light in texture, further reducing any clogging risk.
Summary
Methoxy PEG-100/Polyepsilon Caprolactone Ethylhexanoate is a multitasking polymer that buffers pH, forms a smooth breathable film, conditions hair and provides light to medium styling hold. It achieves these results by combining a water-loving PEG block with an oil-friendly biodegradable polyester block, letting it anchor itself evenly across skin or hair and lock other ingredients in place without stiffness.
While not a household name, the ingredient is quietly popular among formulators who need a gentle alternative to older resins in gels, leave-ins, primers and sheet masks. Consumers may not recognize it on the label, yet they appreciate the soft hold and silky feel it imparts.
Current data show it to be low risk for irritation, allergy and pore clogging, and it is vegan friendly. As with any new cosmetic, it is wise to perform a quick patch test before full use to confirm personal compatibility.