Solvent-Induced Crystallization of Semiaromatic Poly(ester imide)s

Abstract Solvent selection and the chain packing behavior in solution are crucial to the solution processing and material performance of poly(ester imide)s (PEIs). In this work, it was found that specific semiaromatic PEIs can undergo an amorphous-to-crystalline transition in polar solvents, exhibiting typical solvent-induced crystallization behavior. The effects of temperature, concentration, solvent type, and aliphatic chain structure on this crystallization behavior were systematically investigated. Combined with kinetic studies and solid-state nuclear magnetic resonance (NMR) techniques, as well as molecular dynamics simulations, the crystallization mechanism was elucidated, and the solvent-induced crystallization behavior of PEIs was summarized. Additionally, the effects of structural differences among PEI homologues on the morphology of their crystalline products were also investigated. The results demonstrated that the synergistic interplay between the unsymmetric planar structure and the aliphatic chains in semiaromatic PEIs is key to inducing this solvent-induced crystallization behavior. This work not only offers guidance for solvent selection and morphology design in PEI solution processing, but also serves as a valuable reference for PEI material design. In addition, the unusual crystallization behavior provides an alternative perspective for understanding polymer crystallization.