Immiscibility of Chemically Alike Amorphous Polymers: Phase Separation of Poly(2-ethyl-2-oxazoline) and Poly(2-n-propyl-2-oxazoline)

Abstract

In biomedicine, polymer blends are frequently applied in wound dressing design or drug delivery. Within these applications, poly­(2-alkyl/aryl-2-oxazoline)­s (PAOx) are emerging as a popular matrix due to excellent biocompatibility and miscibility with other polymers. However, as much is known of PAOx miscibility with other biocompatible polymer systems, so little is known of the miscibility within the PAOx class. We show the remarkable phase separation of two important, structurally alike, amorphous PAOx, i.e., poly­(2-ethyl-2-oxazoline) and poly­(2-n-propyl-2-oxazoline), that occurs when the polymers’ number-average molar mass exceeds 10 kg·mol–1. The (im)­miscibility as a function of average molar mass is experimentally investigated by thermal analysis, theoretically underpinned by the Flory–Huggins lattice theory, and visualized by fluorescence microscopy in both films and nanofibers, the latter being a high-potential support material in biomedicine. These results provide important knowledge on PAOx (im)­miscibility which has a crucial impact on the behavior of the many final end products they are investigated for.

Tuning the Thermogelation and Rheology of Poly(2-Oxazoline)/poly(2-Oxazine)s Based Thermosensitive Hydrogels for 3D Bioprinting.

“…This finding is particularly interesting as Hoogenboom recently reported that pEtOx and pPrOx homopolymers show immiscibility when the molar mass exceeded 10 kg/mol (i.e. DP ≈ 100) [68]. One might have expected that pEtOx and pPrOzi would be less miscible than pEtOx and pPrOx, but in the present case we have block copolymers at hand, while Hoogenboom and co-workers studied homopolymer blends, which can be expected to phase separate more readily.…”

Tuning the Thermogelation and Rheology of Poly(2-Oxazoline)/Poly(2-Oxazine)s Based Thermosensitive Hydrogels for 3D Bioprinting

“…In contrast, the DSC thermogram of pPrOzi 100 - b -pEtOx 100 showed only a single T g at ≈ 26 °C (slightly higher in comparison to pPrOzi 50 - b -pEtOx 50 T g ≈ 23 °C) suggesting that again no microphase separation ( Figure 2 b) occurred in the solid. This finding is particularly interesting as Hoogenboom recently reported that pEtOx and pPrOx homopolymers show immiscibility when the molar mass exceeded 10 kg/mol (i.e., DP ≈ 100) [ 68 ]. One might have expected that pEtOx and pPrOzi would be less miscible than pEtOx and pPrOx, but in the present case we have block copolymers at hand, while Hoogenboom and co-workers studied homopolymer blends, which can be expected to phase separate more readily.…”

Optical Gain Switching by Thermo‐Responsive Light‐Emitting Nanofibers through Moisture Sorption Swelling

“…Due to the low T g of P n PrOx and its T CP , the nanofibrous structure is not significantly altered upon contact with water at room temperature. [ 49,52 ]…”