Improved Resilience and Uniformity in Polysulfone Blends from an Accelerated Grafting Ring-Opening Polymerization Reaction with Benzoxazine

BPA-based benzoxazine monomer (BA-a) solubilized in end-group ditosylated poly­(ether sulfone) [α,ω-PSU­(OTs)2] undergoes an accelerated grafting ring-opening polymerization (ROP) to afford unique graft copolymer hybrids with predictable thermal properties and improved uniformity and superior mechanical properties. The α,ω-PSU­(OTs)2 was synthesized from the parent α,ω-dihydroxy poly­(ether sulfone) with the conversion of end-groups quantified by 1H NMR and GPC. The two polymers were used to create two blend series with a BPA-based benzoxazine monomer (BA-a) and heated to the polybenzoxazine-based products. The grafting ROP reaction of tosylated poly­(ether sulfone) with the resulting polybenzoxazine network was studied by using DSC, FT-IR, SEM, and UV–vis and indicated that tosylated end-groups accelerate BA-a polymerization and afford products that are composed of P­(BA-a)-graft-PSU with excess but well-mixed PSU. The approach allows for the fabrication of free-standing films that had higher tensile modulus, greater resiliency, and less mechanical property variation compared to their α,ω-dihydroxy poly­(ether sulfone) analogues. The properties of the tosylated poly­(ether sulfone) blend films and the accelerated cure of included benzoxazine allowed for the preparation of thin films on millimeter-scaled metal rods where the mechanically robust films do not undergo significant melt flow when cured by inductive heating.