Brillouin scattering study on crystalline and glassy states of anti-inflammatory racemic S(+)-R(−) ibuprofen

► We investigate acoustic properties of both crystalline and glassy ibuprofen. ► Crystal ibuprofen can be explained by anharmonic lattice models. ► Amorphous ibuprofen exhibits clear change at the glass transition temperature. ► Hydrogen-bonded aggregates seem to affect acoustic damping.