Synthesis and Characterization of Cyclodextrin-Based Polyhemiaminal Composites with Enhanced Thermal Stability

Polyhemiaminal (PHA) polymers are a new class of thermosetting polymers that have recently gained attention owing to their high mechanical strength and excellent recycling behavior. However, low thermal stability is a common issue in PHA polymers due to the thermally labile crosslinked knots. Herein, crosslinked PHA polymer composites were synthesized by reacting formaldehyde with a precursor solution of 4,4MODIFIER LETTER PRIME-oxydianiline (ODA) and cyclodextrins (CDs) (alpha-, beta-, and gamma-). The material obtained under optimal conditions (ODA:CD molar ratio of 1:0.5, 37% aqueous solution of formaldehyde (formalin)) exhibited good film formability and high thermal stability with two characteristic decomposition phenomena and a high char yield. The early decomposition of CDs and char formation led to high thermal stability. Time-resolved NMR analysis was conducted to study hemiaminal bond formation via a condensation reaction between ODA and formaldehyde. Furthermore, PHA matrix formation was confirmed by the dissolution of the deposited CD layer in a solution of N-methyl-2-pyrrolidinone containing 8-9 wt.% LiBr at 80 degrees C and FTIR analysis. Based on the elemental analysis results, PHA network formation was confirmed by considering a single unit of the PHA network with CD composition, including the solvent and water.

Automated summary

Polyhemiaminal (PHA) polymers are a type of newly developed thermosetting polymers with high mechanical strength and excellent recycling properties. However, the low thermal stability of PHA polymers has been a common issue. In this study, crosslinked PHA polymer composites were synthesized and demonstrated to have good film formability and high thermal stability under optimal conditions.