Hydrophobic interaction Hydroxy acids

Aqueous solutions of chitosan-g-PEG and hyamlonic acid-g-Poloxamer undergoing thermal gelation were reported. Aqueous solutions of hydroxy-propyl methylcellulose or methyl cellulose also show thermal gelation. The hydrophobic interactions were suggested as the sol-to-gel transition mechanism. Aqueous solutions of the inclusion complexes between methylated a-... 

The reasonable answer seems to lie in the solute acid s interaction with the resin matrix. An acid with a large alkyl group would have a greater hydrophobic attraction and thus a longer retention time. A hydroxy compound is more polar than its hydrogen analogue and thus would interact less strongly with the resin matrix. 

Owing to the hydrophobic nature of POs, to overcome the lack of possible interactions with a polar substrate, suitable functionalities are inserted during the polymer preparation and/or by post-modification processes, which are generally performed in the melt by radical reactions. Acid, ester, anhydride, hydroxy, amino, oxazoline, and other functionalities have been grafted/anchored onto—or embodied into—the backbone of POs (Boffa and Novak 2000, Passaglia et al. 2009) and these functional POs have been successfully used for providing effective interactions with polar compounds. In particular, depending... 

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