Synthesis and Characterization of Cardo Bisbenzoxazines and their Thermal Polymerization

Abstract

Bisbenzoxazines of bisphenol-C (BCO) and phenolphthalein (PHO) were synthesized by condensing 0.05 mol bisphenol-C/phenolphthalein, 0.2 mol formaldehyde, and 0.1 mol aniline. Both BCO and PHO were thermally polymerized via ring-opening polymerization. The resultant cross-linked polymers (PBCO and PPHO) were characterized by solubility, Infrared (IR), Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The bisoxazines and their polymers followed two-step degradation. Both BCO and PHO undergo selective ring-opening polymerization over the temperature range 100–150°C and are thermally stable up to about 250°C. The % residue at 550°C is substantially higher for PHO samples (56–67%) than BCO samples (20–25%), indicating the highly thermally stable nature of PHO. A ring transformation reaction is also supported by DSC. New thermosetting materials may be useful for specific applications to be exploited.

Keywords:

• Benzoxazine
• Solubility
• IR
• NMR
• TGA
• DSC

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Erratum

ACKNOWLEDGMENTS

The authors are thankful to Directors, RSIC-Chandigarh, and SICART-V. V. Nagar for spectral and thermal analysis.