What Is Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer?
Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer is a man-made ingredient created by linking two different monomers: isobutylmethacrylate, which belongs to the acrylic family, and bis-hydroxypropyl dimethicone acrylate, a silicone-based monomer. When these small building blocks are joined together they form a large, flexible molecule called a copolymer. This union gives the final material a balance of acrylic strength and silicone smoothness.
The rise of lightweight long-wear makeup in the late 1990s drove chemists to look for new film formers that could resist water and smudging without feeling tight on skin. By combining an acrylic monomer with a modified silicone, formulators achieved a copolymer that met those goals, and it has been part of color cosmetics and skin care ever since.
The copolymer is made through a controlled reaction called free-radical polymerization. The two monomers are mixed with an initiator that starts the reaction, causing them to link into long chains. Once the reaction reaches the desired length, it is stopped, the material is purified, then dried into a fine powder or dispersed in a solvent ready for use.
You will most often find this ingredient in products that need a flexible, breathable film on the skin such as liquid foundations, BB creams, long-wear concealers, waterproof eyeliners, mascaras and liquid lipsticks. It also appears in certain primers, smoothing serums and some sheet mask essences where a light sealing layer is helpful.
Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer’s Cosmetic Benefits/Uses
This ingredient is valued for its film forming ability, meaning it spreads into a thin, even layer that dries to create a protective but comfortable film on the skin or hair. The film helps lock pigments in place, boost water resistance, minimize transfer onto clothing, reduce feathering around fine lines and improve overall wear time. Because the copolymer contains silicone segments, the resulting film feels smooth and flexible rather than crunchy, so makeup stays comfortable even after hours of wear.
Who Can Use Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer
This copolymer suits most skin types because it forms a lightweight, breathable film that does not alter the skin’s natural moisture balance. Normal, dry, combination and oily skins generally tolerate it well. Extremely sensitive or highly acne-prone users might want to monitor for congestion or warmth under the film, as any occlusive layer can occasionally trap sweat or bacteria and trigger flare-ups.
The ingredient is fully synthetic and contains no animal-derived substances, so it is compatible with vegan and vegetarian lifestyles. Always check the full product label though, as other ingredients or processing aids in the same formula might not share that status.
No evidence suggests that topical use poses a risk during pregnancy or while breastfeeding because the large polymer molecules stay on the surface of skin and do not reach the bloodstream. This is not medical advice; anyone who is pregnant or nursing should review all skincare choices with a qualified healthcare provider.
The copolymer does not make skin more sensitive to the sun and can even help hold sunscreen in place. It has no known interactions with common actives like vitamin C, niacinamide or retinoids.
Potential Side Effects/Adverse Reactions
Reactions to Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer vary from person to person. The following are possible outcomes, not the norm. When the ingredient is used correctly in a well-formulated product, most people experience none of these issues.
- Mild redness or stinging in individuals with very reactive skin
- Contact dermatitis in those allergic to acrylic compounds
- Temporary clogged pores or breakouts if the formula is overly occlusive for the user’s skin type
- Eye irritation if the product accidentally gets into the eyes during application or removal
- Allergic rash around nails when used in gel nail products for someone already sensitized to methacrylates
If any irritation, swelling or rash develops while using a product that contains this ingredient, stop using it and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 1/5 – The molecule is large and inert, so it sits on top of skin rather than sinking into pores. It creates a breathable film that is light and silicone rich, which means it is far less likely to trap oil or bacteria than heavier waxes or mineral oils. However, in very thick or layered formulas it can still slow evaporation of sweat and sebum for some users, which is why it does not score a perfect zero.
Suitable for acne-prone or breakout-prone skin in most cases.
Keep in mind that the full product recipe matters; rich creams or heavy makeup bases that also contain butters or oils may feel more occlusive even if this copolymer itself is practically non-comedogenic.
Summary
Isobutylmethacrylate/Bis-Hydroxypropyl Dimethicone Acrylate Copolymer is mainly a film former, laying down a thin flexible coat that locks pigments in place, boosts water resistance and keeps makeup comfortable. The acrylic portion delivers grip and durability while the silicone portion adds slip and softness so the film bends with facial movement instead of cracking.
You will see it most often in long wear foundations, eyeliners and liquid lip colors rather than in basic cleansers or lotions, so its popularity is strongest in color cosmetics where performance and staying power matter.
Topically the ingredient is considered very safe because its large polymer chains do not penetrate skin and it has a low allergy record. Still, every formula is different so give any new product a small patch test to be sure it agrees with your skin.