Intercalation Characteristics of Montmorillonite Modified with Poly(2-n-alkyl-2-oxazoline)s

Poly(2-oxazoline)s (POxs) are nonionic polymers suitable for different bioapplications. Composites of montmorillonite (Mnt) and poly(2-methyl-2-oxazoline) (PMeOx), poly(2-ethyl-2-oxazoline) (PEtOx), and poly(2-propyl-2-oxazoline) (PPrOx) were prepared for the first time, and the effect of polymer loadings and the side chain length on the adsorption and structural characteristics was examined. Adsorption isotherms of polymers revealed a sharp increase in adsorption at low polymer loadings. When the surface of Mnt was saturated with POxs, a plateau not changing with the loading of the polymer appeared. The highest adsorption capacity was found for PMeOx (4.15 mmol g–1) followed by PEtOx (3.86 mmol g–1) and PPrOx (3.14 mmol g–1). The interlayer space of Mnt gradually increased with increasing POxs content from 0.5 to 6.0 mmol g–1. No further changes were observed at loadings above 6.0 mmol g–1. The intensities of the bands related to the vibrations of the C═O and CH3 and CH2 groups increased with increasing amounts of polymers. A slight shift of the band position reflected the transition from disordered (cis conformers) to more ordered (trans conformers) polymer arrangement.