High-T-g and Degradable Isosorbide-Based Polybenzoxazine Vitrimer

This work describes new fully bio-based vitrimers prepared from isosorbide, a renewable sugar-based chemical. Isosorbide was reacted with 4-hydroxypropionic acid, paraformaldehyde, mono-ethanolamine, and/or furfurylamine via consecutive solvent-free Fischer esterification and Mannich-like ring-closure reactions. The two-step synthesis led to the formation of a ditelechelic benzoxazine-terminated isosorbide monomer, containing ester bonds and aliphatic hydroxyl and/or furan groups. The atom economy factor yields 85%. The structural features of the resulting products were substantiated by spectroscopic techniques. The ring-opening polymerization was monitored by rheological and differential scanning calorimetry (DSC) measurements. Very high T-g values afforded by the isosorbide substructure were measured (from 143 to 193 degrees C), which increase with furan ring content. Internally catalyzed transesterification reactions conferred fast dynamic exchanges (tau* = 300 s at 180 degrees C). Self-healing and chemical and mechanical recycling were also demonstrated. Finally, the degradability of the sugar-based polybenzoxazine vitrimers was demonstrated as well. The materials were highly stable in pH-neutral water, even at 80 degrees C for 60 days, but owing to the isosorbide structure, pronounced degradation was observed under acidic or alkaline conditions. In summary, isosorbide is a suitable building block for the design of degradable and 100% recyclable high-T-g polybenzoxazine vitrimers.

Automated summary

This work introduces new fully bio-based vitrimers derived from isosorbide, showcasing high T-g values and fast dynamic exchanges, as well as self-healing and chemical and mechanical recycling capabilities. However, the materials are prone to degradation under acidic or alkaline conditions due to the isosorbide structure.