What Is Lauroyl Pei-233/Polycaprolactone Copolymer?
Lauroyl Pei-233/Polycaprolactone Copolymer is a lab made ingredient created by linking together two building blocks: polycaprolactone, a biodegradable polyester, and lauroyl-modified polyethyleneimine (often shortened to PEI-233). Chemists react 2-oxepanone, a ring shaped molecule, with aziridine units, then cap part of the chain with lauric acid to get a stable hybrid polymer. The result is a smooth waxy material that melts easily into oils yet disperses in water when blended with the right surfactants.
The polymer first drew interest in the late 1990s when researchers were looking for gentle alternatives to traditional detergents in skin care. Because its backbone is similar to those used in medical sutures, suppliers recognized it could be safe for topical use. Over time formulators discovered that the ingredient helps oil and water stay mixed without leaving a heavy feel so it began appearing in prestige moisturizers, lightweight lotions and rinse off masks.
Today you will most often find Lauroyl Pei-233/Polycaprolactone Copolymer in face creams, fluid sunscreens, anti aging serums, hair conditioners and cleansing balms where a velvety but non greasy texture is desired.
Lauroyl Pei-233/Polycaprolactone Copolymer’s Cosmetic Benefits/Uses
In personal care products this multifunctional polymer is valued mainly for one key role:
Emulsifying – It acts as a bridge between oil and water so formulas stay uniform from the first pump to the last. This improves product stability, prevents separation during storage and helps deliver both water loving and oil loving actives evenly across the skin or hair. Thanks to its mild nature it supports gentle, low-irritation emulsions suitable for sensitive skin while contributing to a silky afterfeel.
Who Can Use Lauroyl Pei-233/Polycaprolactone Copolymer
This polymer is lightweight and non occlusive so it generally suits dry, oily and combination skin without clogging pores or leaving a heavy film. Its mild profile makes it friendly for sensitive skin too, as it carries little risk of stinging or redness.
The material is synthesized entirely from lab sourced chemicals; no animal derived components are involved in its production, which means products made with it are typically appropriate for vegans and vegetarians. Still, certification depends on the rest of the formula and brand policies.
No studies have linked Lauroyl Pei-233/Polycaprolactone Copolymer to hormonal disruption or developmental toxicity, so it is not specifically restricted during pregnancy or while breastfeeding. That said, this is not medical advice. Expectant or nursing users should always review any skincare product with their doctor to be safe.
The ingredient does not make skin more sensitive to sunlight and does not interfere with sunscreens, so no extra daylight precautions are needed beyond normal SPF use.
Potential Side Effects/Adverse Reactions
Responses to topical Lauroyl Pei-233/Polycaprolactone Copolymer differ from person to person. The issues listed below are only potential effects and are unlikely for most users when the ingredient is used at standard cosmetic levels.
- Mild skin irritation – Rare tingling or redness can occur in very reactive skin, usually subsiding once the product is removed
- Allergic contact dermatitis – Although uncommon, some individuals may develop a localized rash due to sensitivity to the polymer or other formula components
- Eye irritation – If a product containing the polymer accidentally enters the eyes it may cause temporary discomfort or watering
If any persistent burning, swelling or rash develops discontinue use and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 1 out of 5
This low score reflects the polymer’s lightweight non occlusive nature. Its backbone is a breathable polyester that does not sit heavily on the skin and it contains no long chain fatty alcohols or waxes typically linked with clogged pores. Formulas that include it usually rely on additional low oil phases so the overall breakout risk remains minimal.
Suitable for acne-prone and breakout-prone skin, provided the rest of the product is also low in comedogenic ingredients.
No extra concerns have been flagged regarding fungal acne since the molecule is not a triglyceride or fatty acid that Malassezia yeasts feed on.
Summary
Lauroyl Pei-233/Polycaprolactone Copolymer works mainly as an emulsifier, keeping oil and water blended so creams, lotions and sunscreens stay smooth and stable. The hybrid polymer has both water-friendly amine groups and oil-loving lauroyl chains, which lets it anchor at the oil-water interface and create a fine, silky emulsion.
While not a household name, it has a steady following among formulators looking for gentle, velvety textures. You will spot it more often in mid to high tier skincare than in basic drugstore lines.
Current research and real-world use show it is well tolerated with a very low risk of irritation or pore clogging. Still, everyone’s skin is unique so it is smart to patch test any new product that lists this ingredient before applying it widely.