Solvents such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) have been recommended for polyurethane, as you may want to check from the following discussions at this forum: https://www.researchgate.net/post/Which_is_the_best_solvent_to_dissolve_polyurethane_elastomer https://www.researchgate.net/post/What_is_the_best_solvent_or_blend_of_solvents_for_polyurethane_to_make_electrospun_nanofibers2