Comments on “volumetric studies of aqueous polymer solutions using pressure perturbation calorimetry …” [Macromolecules 34 (2001) 4130]

Although, pressure perturbation calorimetry has been applied to a novel problem by Kujawa and Winnik [Macromolecules 34 (2001) 4130], their failure to appreciate earlier work on this method led to instrumental and methodological errors of unknown magnitude discussed in this note. The design and operation of the commercial instrument used by Kujawa and Winnik is shown to be flawed.