POLYURETHANE-24/METHYL METHACRYLATE CROSSPOLYMER is an inorganic chemical compound, a segmented block copolymer derived from urethane and synthesised from isocyanates.
Significant substances used in the production method:
Polyurethane-24, Methyl Methacrylate, methacryloxypropyltriethoxysilane.

Safety
Polyurethanes are rather complex, inert and biostable materials that are also used in biomedical applications. They are typically synthesised by the reaction of a glycol or polyol with polyisocyanate or diisocyanate. It is known that exposure to isocyanates can cause asthma, contact allergies, conjunctival and skin irritation. However, a study by the Cosmetic Ingredient Review Expert Panel in 2017 found that the rates of harmful residues are not significant for human health.
https://www.cir-safety.org/sites/default/files/Polyur092017FR.pdf

Urethane (also called ethyl carbamate) is a by-product of fermentation and is considered a genotoxic agent.

What it is used for and where
Cosmetics

Hair fixative. This ingredient has the ability to create, with its protective film, stiffness and hold in the hair, and also has the ability to form, with its hydrophilic and elastic properties, bonds between the hair fibres, to keep the hair in a particular shape for a certain time.
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