What Is Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer?
Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer is a lab-made polymer created by taking liquid polybutadiene, turning its double bonds into single bonds through hydrogenation, then linking the chains to an isophorone diisocyanate (IPDI) unit that carries methylisocytosine groups. The starting polybutadiene comes from petroleum-derived butadiene gas, which is first converted into a rubbery homopolymer. After hydrogenation the material is more stable and less prone to oxidation. Chemists then add hydroxyl groups to the ends of the chains so they can react with IPDI, forming tough yet flexible urethane bonds. The methylisocytosine segment gives extra affinity for skin and improves how the polymer sits on the surface.
Film-forming polymers like this one began appearing in cosmetics in the late 1980s when brands searched for longer-wear colour products. Over time newer versions were engineered to be lighter, more breathable and easier to remove. This specific copolymer is popular in long-wear foundations, mascaras, liquid eyeliners, transfer-proof lipsticks, setting sprays, peel-off masks, anti-aging serums and water-resistant sunscreens.
Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer’s Cosmetic Benefits/Uses
In formulas this ingredient mainly acts as a film former, which brings several useful perks.
As a film former it spreads into a thin, flexible layer that locks pigments in place, boosts water resistance, cuts down smudging and helps active ingredients stay on the skin for longer. The film also reduces moisture loss so products feel smoother and last through heat, sweat or humidity.
Who Can Use Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer
This polymer is generally well tolerated by all skin types. Normal, dry and combination skin often appreciate the breathable film it leaves. Oily or acne-prone users can also use it, though very congested skin might prefer lighter textures because any film former can trap sebum if cleansing is not thorough.
The ingredient is completely synthetic and contains no animal derivatives, so it is suitable for both vegans and vegetarians.
Current safety data indicate no known risks for pregnant or breastfeeding women when the polymer is applied topically. That said this is not medical advice and anyone who is pregnant or nursing should run any skincare product past a doctor to be on the safe side.
The material does not absorb UV rays or make skin more sensitive to sunlight, so it is not linked to photosensitivity. It is also safe for use around the eye area in mascaras and eyeliners.
Potential Side Effects/Adverse Reactions
Side effects and reactions to the topical application of Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer can vary from person to person. The following is a list of potential side effects that are unlikely to occur for most users when the ingredient is used correctly in a finished product:
- Mild skin redness or irritation in extremely sensitive individuals
- Temporary clogged pores if makeup is not fully removed at night
- Rare cases of contact dermatitis for people allergic to urethane chemistry
- Watery eyes or stinging if a high concentration enters the eye before it sets
- Product build-up causing a tight feeling when multiple long-wear layers are applied without proper cleansing
If you experience any of these reactions stop using the product and consult a healthcare professional.
Comedogenic Rating
Rating: 1/5
This polymer sits on top of the skin in a very thin flexible layer and has a large molecular size, so it is unlikely to seep into pores and block them. It contains no oily plant butters or waxes that usually trigger breakouts, which keeps its clogging potential low. The slight risk comes from the film itself trapping excess sebum if makeup is not removed carefully, giving it a score of 1 rather than 0.
Suitable for acne-prone or breakout-prone skin provided the product is properly cleansed off at the end of the day.
Because it is often paired with long-wear pigments and silicones, the overall formula may feel heavier than regular makeup, so double cleansing is a good habit when using products that rely on this polymer.
Summary
Bis-Methylisocytosine Hydrogenated Polybutadiene/Ipdi Copolymer is a synthetic film former that creates a breathable yet tough layer on skin. This film locks in pigments, boosts water and sweat resistance and helps active ingredients stay put for longer wear.
Thanks to these perks it shows up in many long wear foundations, liquid lipsticks, waterproof mascaras and setting sprays, though it is still a niche ingredient compared to classic film formers like acrylates or PVP.
Current data show it is low risk for irritation or sensitization and its comedogenic rating is only 1, making it generally safe for most skin types. As with any new cosmetic ingredient it is wise to patch test a fresh product before full use just to be sure your skin agrees with it.