The subject matter of the present invention is a photopolymerizable liquid composition comprising at least one epoxidized polybutadiene prepolymer, at least one cationic photoinitiator, and at least one thioxanthone-derived photosensitizer, which can, for example, be in the form of a liquid dressing. The subject matter of the invention is also a process for obtaining a polymerized film from said photopolymerizable liquid composition, characterized in that said composition is applied to tissues such as the skin, the skin appendages or the mucous membranes so as to form a uniform liquid film, and the film thus obtained is subjected to ultraviolet radiation, preferably ultraviolet-visible radiation having a wavelength of between 380 and 405 nm, preferably between 385 and 395 nm.