Studies of relationship between polymer structure and hydration environment in amphiphilic polytartaramides

The relationships between the chemical structures and hydration environment of the polymers can provide significant insight into the water-amphiphilic polymer interactions. Here, the hydrophobicity of amphiphilic block copolymers poly(ethylene tartaramide-b-alkyl isocyanate) is gradually tuned by using of a series of pendant alkyl (isopropyl, n-butyl, cyclopentyl, and cyclohexyl) groups. Dynamics of hydration probed by low-field NMR relaxometry exhibits a heterogeneous environment of water molecules, corresponding to tightly bound water with slow re-orientational mobility and loosely bound water with fast re-orientational mobility. Progressively larger amounts of bound water are present in the copolymers, ongoing from pendant isopropyl, n-butyl, cyclopentyl, and finally to cyclohexyl group. Water in the copolymer bearing the cyclohexyl group has a significantly high partial specific heat capacity. Therefore, hydrophobic interaction between the polymer and water is enhanced when the hydrophobicity of the polymer is increased, resulting in considerable hydrophobic hydration with decreased mobility of the bound water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016.