Synthesis, dynamic mechanical properties, and shape memory effect of polybenzoxazines based on monofluorophenol isomers and polyetheramines

Abstract Two series of benzoxazines are synthesized from a set of isomeric monofluorophenols ( o -, m -, and p -fluorophenols), two polyetheramines (Jeffamine D230 and D400), and formaldehyde. The chemical structures of the benzoxazines are confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. For m -fluorophenol-based benzoxazines, the two sets of data appeared in the 13 C, DEPT-135, and 19 F NMR spectra indicate that each product obtained is a mixture of two isomers. The ring-opening polymerization temperatures for ortho , meta , and para isomers in the two series of benzoxazines are in descending order para  >  ortho  >  meta . The glass transition temperatures ( T g s) of the resultant polybenzoxazines are in ascending order ortho para meta . The polybenzoxazines exhibit thermally induced one-way dual-shape memory effect based on T g , and the shape memory performance are excellent in tensile, bending, and twisting tests. Under motion constraints in a tensile deformation mode, the D400-based polybenzoxazines show higher shape recovery ratios compared with the corresponding D230 counterparts.