Dynamic and structural insights into hydrogen-bonded interpolymer complexes of poly(2-alkyl-2-oxazolines) with poly(carboxylic acids).

The formation of interpolymer complexes (IPCs) between poly(2-alkyl-2-oxazolines) (PAOx) and poly(methacrylic acid) (PMAA) in solutions has been investigated using polarized luminescence relaxation and small-angle X-ray scattering (SAXS) structural methods. The results reveal that hydrophobic interactions contribute to the formation of IPCs in both aqueous and methanol solutions, influenced by the length of the side group in PAOx. The relaxation times, which can be used to quantify the intramolecular mobility of the luminescently labeled poly(methacrylic acid) (PMAA*), increase from 80 to 680 ns, indicating the formation of IPCs between PMAA* and PAOx. SAXS analysis of aqueous IPC solutions unveils their supramolecular organization, which is similar to that of nanohydrogels, with the hierarchical level comprising compact structures ranging from 4 to 10.7 nm in size.