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

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Polyhemiaminal (PHA) polymers offer high mechanical strength and recyclability.
• A key limitation of PHA polymers is their low thermal stability due to labile crosslinked structures.
• Enhancing thermal stability is crucial for broader PHA polymer applications.

Purpose of the Study:

• To synthesize crosslinked PHA polymer composites with enhanced thermal stability.
• To investigate the role of cyclodextrins (CDs) in improving PHA thermal properties.
• To characterize the structure and formation of the novel PHA-CD composites.

Main Methods:

• Synthesis of PHA composites via reaction of formaldehyde with 4,4'-oxydianiline (ODA) and cyclodextrins (α-, β-, γ-CDs).
• Optimization of ODA:CD molar ratio and formaldehyde concentration.
• Characterization using time-resolved NMR, FTIR, elemental analysis, and solubility tests.

Main Results:

• Optimal conditions (ODA:CD 1:0.5, 37% formalin) yielded PHA composites with good film formability and high thermal stability.
• Early decomposition of CDs and subsequent char formation contributed to enhanced thermal resistance.
• NMR and FTIR confirmed hemiaminal bond formation and PHA matrix development.

Conclusions:

• Crosslinked PHA polymer composites incorporating cyclodextrins exhibit significantly improved thermal stability.
• The synergistic effect of CDs and char formation is key to enhancing PHA thermal performance.
• This work presents a viable strategy to overcome thermal limitations in PHA polymers.