What Is Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/Tmhdi Copolymer?
Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/TMHDI Copolymer is a lab-made ingredient created by linking together two building blocks: poly(1,4-butanediol), a flexible synthetic polymer, and trimethylhexanediisocyanate, a hardening agent. The ends of this chain are capped with hydroxyethyl acrylate, which lets the finished material bond well to water-based formulas. The copolymer was first explored in the early 2000s when chemists searched for lightweight film formers that could replace heavier resins in skin care and makeup. By tweaking the ratio of its parts scientists found a way to produce a clear, breathable film that feels barely there on skin.
Production starts with controlled polymerization of 1,4-butanediol to create short, uniform chains. These chains react with trimethylhexanediisocyanate, which stiffens the structure and improves durability. Finally hydroxyethyl acrylate is added to each end of the new polymer so it can disperse evenly in water or alcohol. The resulting copolymer is purified, dried into a fine powder or delivered as a liquid concentrate, then blended into cosmetic bases.
You will most often see it in long-wear foundations, tinted moisturizers, BB creams, liquid and pencil eyeliners, peel-off face masks, hair styling sprays and certain hand or body creams that promise “no transfer” or “all day hold.”
Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/Tmhdi Copolymer’s Cosmetic Benefits/Uses
This ingredient is valued for one main job in cosmetics.
Film forming: When the product dries the copolymer creates an invisible, flexible layer on skin or hair. This film locks in active ingredients, boosts water resistance, reduces smudging, helps makeup stay put longer and gives skincare formulas a smooth soft finish without a heavy feel.
Who Can Use Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/Tmhdi Copolymer
The breathable film this copolymer creates means it suits most skin types, including oily, combination, normal and mildly dry skin. Those with very dry or eczema-prone skin might find the film slightly tight if the formula around it lacks sufficient moisturizers. Sensitive skin users generally tolerate it well because it has no fragrance or preservatives of its own, yet anyone with a known acrylic allergy should proceed cautiously.
The ingredient is produced entirely from synthetic raw materials so it is considered vegan and vegetarian friendly with no animal derivatives or by-products involved in manufacturing.
There is no evidence that topical use poses any risk to women who are pregnant or breastfeeding and the copolymer is not absorbed into the bloodstream. This is not medical advice and pregnant or nursing women should run any skincare product past their doctor just to be on the safe side.
Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/TMHDI Copolymer does not make skin more sensitive to sunlight and it remains stable when layered under sunscreens. It is also odorless colorless and compatible with both water and alcohol bases which makes it versatile in day or night products.
Potential Side Effects/Adverse Reactions
Reactions to topical Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/TMHDI Copolymer vary from person to person. The points below list potential side effects only; most users experience none of these when the ingredient is properly formulated.
- Mild redness or irritation
- Stinging or watering if product migrates into the eyes
- Contact dermatitis in individuals allergic to acrylate or isocyanate compounds
- Temporary tight or dry feeling on very dehydrated skin
- Clogged pores if the finished product also contains heavy oils and is not thoroughly removed
- Rare allergic reaction such as itching swelling or hives
If any negative reaction occurs stop using the product immediately and consult a healthcare professional.
Comedogenic Rating
Rating: 1 / 5 (very low)
Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/TMHDI Copolymer forms a light, breathable film that sits on the surface of skin rather than seeping into pores. It contains no oils, waxes or fatty acids that typically cause congestion. Because it dries into a flexible lattice it is unlikely to trap sebum on its own, giving it a very low likelihood of clogging pores.
Suitable for acne-prone skin, as long as the overall formula is lightweight and properly removed at the end of the day.
If the product also includes heavy emollients or if the film is left on overnight without cleansing, buildup could still occur so cleanse thoroughly.
Summary
Bis-Hydroxyethyl Acrylate Poly(1,4-Butanediol)-9/TMHDI Copolymer is primarily a film former that creates a clear, flexible shield on skin or hair. This film locks in actives, resists water and sweat and keeps makeup from smudging while leaving a weightless feel. It achieves these results through its unique polymer backbone: the butanediol segments add softness while the trimethylhexanediisocyanate segments add strength, and the hydroxyethyl acrylate end groups let the polymer disperse smoothly in water-based formulas.
Although not as famous as silicone resins or PVP, it is gaining quiet popularity in long-wear foundations, eye products and modern peel-off masks thanks to its breathable finish and vegan origin.
Safety data show it is non-sensitizing for most users and stays on the skin surface rather than absorbing systemically, making it a low-risk choice when properly formulated. As with any new cosmetic ingredient, do a quick patch test when trying a product that contains it to rule out individual sensitivities.