Abstract
Polybenzoxazines are very interesting phenolic resins that are obtained by ring-opening polymerisation(ROP) of benzoxazine monomers. However, commercially available resins such as bisphenol A-anilinebenzoxazine (BA-a) have found limited industrial applications, partly due to their high ROP temperature.To tackle this limitation, we designed a 2-substituted benzoxazine monomer bearing a phenol, Ph-fa[2]PhOH, which was obtained by different methods of solvent-free and environmentally friendly synthesis,such as ball-milling and bladeless planetary mixing. The phenol functionalisation leads to a high reactivity,thanks to the hydrogen-bond activation of the oxazine ring. Ph-fa[2]PhOH showed one of the lowestROP temperatures ever reported (ca. 160 °C) and a low activation energy (Eα) of 40–70 kJ mol−1 as determined by the Vyazovkin kinetic method. The high reactivity of this monomer was advantageously exploitedfor the reduction of the ROP temperature of the commercial BA-a benzoxazine. By studying the curingprocess by non-isothermal DSC after different polymerisation stages of a formulation containing 10 wt% ofour new monomer with BA-a precursors, we were able to evaluate its acceleration effect. In addition, weshowed that Ph-fa[2]PhOH was able to improve the Tα of the crosslinked network by 10 °C and the charyield by 10%, leading to a significant improvement in the properties of the commercial BA-a resin