ABSTRACT Poly(2‐oxazoline)‐imidazole (POZ‐Im) polymers were synthesized by one‐pot termination of 2‐ethyl, 2‐propyl‐, and 2‐phenyl‐2‐oxazoline homopolymers with imidazole and evaluated as thermal latent curing agents (TLCs) for one‐component epoxy resins (OCERs). 1 H NMR, FTIR, and MALDI‐TOF confirmed successful synthesis of polymers. The polymers were amorphous, exhibiting glass transition temperatures of 43°C (PEOZ‐Im), 24°C (PPrOZ‐Im), and 91°C (PPhOZ‐Im) and showed thermal stability with onset degradation at 364°C–375°C. When incorporated into DGEBA at a fixed 5 phr Im‐to‐epoxy ratio, their miscibility and curing performance varied with side‐chain chemistry. PPhOZ‐Im was fully miscible, PPrOZ‐Im was partially miscible, and PEOZ‐Im formed fine dispersed domains. Dynamic DSC revealed left‐limit temperatures of 91.75°C (PEOZ‐Im), 94.22°C (PPhOZ‐Im), and 103.28°C (PPrOZ‐Im). Rheological analysis showed that PPrOZ‐Im/DGEBA exhibited the longest gelation time, followed by PEOZ‐Im/DGEBA and PPhOZ‐Im/DGEBA. Shelf‐life estimations based on viscosity doubling times and Arrhenius extrapolation indicated stability of 88 days (PPrOZ‐Im/DGEBA), 34 days (PEOZ‐Im/DGEBA), and 32 days (PPhOZ‐Im/DGEBA) at −20°C. These results demonstrate that POZ‐Im polymers provide tunable latency and curing behavior suitable for advanced composite applications.
Ozsaltik et al. (2026) studied this question.