For the development of a successful PMs system, the primary mission is to select a polymer which is not only compatible with the cargo but also provide colloidal stability even at high relative and absolute cargo concentrations. There are a variety of physicochemical techniques available to determine the compatibility between polymer and drugs, but most of these are time-consuming, expensive and laborious . For the development of cost-effective and efficient drug delivery system, it is usually desirable to predict theoretically the extent of compatibility between polymer and drugs before any experimentation. For many years, Hansen solubility parameters (HSPs) were routinely employed for estimation of compatibility between solute and solvent especially in paint/polymer industry . More recently, HSPs are used in other areas like cosmetics , drugs , oligomers or gel formation and nanoparticles . To guide formulation development, Allen and the co-workers calculated HSPs to estimate the compatibility between model drug ellipticine and a variety of chemically diverse polymers. Overall, a good correlation was observed between theoretical compatibility profile and experimental results of the formulation . Importantly, as the HSPs are calculated by various group contribution methods so the polymers which are closely related or structural isomers would yield the same HSPs values and in turn represent the similar compatibility for the drugs. In contrary, Lübtow et al. observed the distinct polymerdrug specificities in POx/POzi based micellar formulation, although the polymers differed by only one methylene unit in the side chain or the backbone (structural isomers) of hydrophobic block .