From a previously investigated library of 18 different ABA triblock copolymers , we selected 3 best performing polymers with respect to drug solublization. In all the selected polymers the hydrophilic block A is always poly(2-methyl-2-oxazoline) and comprising moderately hydrophobic block B i.e. poly(2-n-butyl-2-oxazoline) (pBuOx), poly(2-n-propyl-2oxazine) (pPrOzi) and poly(2-n-butyl-2-oxazine) (pBuOzi). All of these polymers were previously investigated for drug formulation and have shown promising results . As all the triblock copolymers comprised of pMeOx as A, so they are represented according to hydrophobic block i.e. A-pBuOx-A, A-pPrOzi-A, and A-BuOzi-A. To this mini-library, we added a fourth polymer (less commonly explored) comprised of hydrophobic poly(2-n-pentyl-2oxazoline) (pPentOx) block. Recently, the polymer A-pPentOx-A was reported to have ultrahigh LC of 47 wt.% for new investigational molecule i.e. BT-44 . The targeted block length for each block in triblock copolymer is A35-B20-A35. For synthesis and characterization of four triblock copolymers, the readers are referred to previous reports . These four polymers represent two pairs of structural isomers. i.e. they differ from each other by one methylene unit which is shifted from polymer backbone to the side of hydrophobic block and vice versa (A-pBuOx-A/A-pPrOzi-A and A-PentOx-A/A-pBuOzi-A).