C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 24, 2025
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All information on this page is verified using publicly available nomenclature standards and reference materials from The Personal Care Products Council (PCPC) and the European Commission's CosIng database. Our analyses are based on technical data from these sources to ensure accuracy and reliability.

What Is C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer?

C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer is a silicone based material made by linking long chain alkyl dimethicone with a polyether derived from vinyl cyclohexene oxide. The result is a soft flexible network that combines the silky feel of dimethicone with the light, breathable touch of a polyether. Silicones like dimethicone have been used since the 1950s to give products a smooth glide, and chemists later began cross-linking them with other molecules to improve texture and staying power. This particular crosspolymer was introduced in the early 2000s when brands started looking for weightless alternatives to heavy oils.

To create it, manufacturers blend C30-45 alkyl dimethicone with vinyl cyclohexene oxide, then trigger a controlled reaction that bonds the two into a 3-D mesh. The finished ingredient looks like a clear gel or soft wax that disperses easily in oils or silicones. Because it can form an invisible film without feeling greasy, formulators add it to primers, liquid foundations, pressed powders, tinted moisturizers, setting sprays, sunscreens, hair serums, masks and anti-aging creams.

C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer’s Cosmetic Benefits/Uses

This multitasker offers several perks when blended into skincare or makeup.

  • Film forming – creates a thin flexible layer on the skin that locks in moisture, smooths texture and helps makeup last longer even in humid or sweaty conditions
  • Skin conditioning – leaves the surface soft and supple by filling in tiny gaps between skin cells for an instant silky finish
  • Emollient – adds slip so products spread evenly, reduces the drag you can feel during application and diminishes the look of fine lines by sitting in them and reflecting light

Who Can Use C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer

This silicone crosspolymer suits nearly all skin types thanks to its weightless feel and breathable film. Dry or mature skin benefits from its emollient slip while oily and combination skin appreciate that it is non greasy and low on the pore clogging scale. Sensitive skin usually tolerates it well because it is chemically inert and fragrance free, but anyone extremely prone to breakouts may want to monitor how their skin reacts when layering several silicone rich products.

The material is fully synthetic with no animal derived raw materials so it fits vegan and vegetarian lifestyles provided the finished product is cruelty free.

C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer is regarded as safe for use during pregnancy and breastfeeding because it stays on the skin surface rather than being absorbed. This is not medical advice and pregnant or nursing individuals should show any skincare they plan to use to a doctor just to be sure.

The ingredient is not known to cause photosensitivity so there is no extra need for sun avoidance beyond standard daily SPF use. It is also compatible with common actives like retinoids and vitamin C and does not interfere with them.

Potential Side Effects/Adverse Reactions

Responses to topical C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer can differ from person to person. The points below list potential issues but most people will not notice any problems when the ingredient is used correctly in a well formulated product.

  • Clogged pores or minor breakouts in individuals who are highly silicone sensitive or already prone to acne
  • Rare contact dermatitis such as redness itching or rash in those with a true silicone allergy
  • Temporary stinging if applied to freshly exfoliated or compromised skin
  • Product pilling or build up when multiple layers of silicone heavy formulas are applied without proper cleansing

If any irritation or other negative effect occurs stop using the product and seek advice from a healthcare professional or dermatologist.

Comedogenic Rating

Rating: 1/5. This crosslinked silicone forms a breathable mesh that rests on top of the skin rather than sinking into pores which keeps its clogging potential very low. The large molecular structure and slick texture help it glide away during cleansing reducing residue build-up. People who easily break out can generally use it without trouble although they may want to keep an eye on how many other silicones are layered with it. Formulas that also contain heavy oils or waxes may raise the overall comedogenic load so the full product matters more than this single ingredient.

Summary

C30-45 Alkyl Dimethicone/Polycyclohexene Oxide Crosspolymer acts as a film former skin conditioner and emollient. Its three-dimensional silicone-polyether network lays down a thin flexible film that locks in moisture smooths texture and helps makeup grip while the silky emollient slip makes application effortless and softens the look of fine lines. Although not as famous as classic dimethicone it is gaining quiet popularity in primers long-wear foundations and lightweight sunscreens where brands want a weightless cushiony feel without greasiness. Safety reviews show it is non-sensitising non-irritating and non-phototoxic which makes it suitable for most users. As with any new cosmetic ingredient it is wise to patch test a product that contains it to confirm personal tolerance.

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