The thermodynamic properties of dark energy fluids described by an equation of state parameter $ω=p/ρ$ are rediscussed in the context of FRW type geometries. Contrarily to previous claims, it is argued here that the phantom regime $ω0$ and $S>0$ in the course of the Universe expansion. Further, the negative value of the chemical potential resulting from the entropy constraint ($S>0$) suggests a bosonic massless nature to the phantom particles.

14 pages, no figures, text revised