Pegylated Polybenzoxazine Networks with Increased Thermal Stability from Miscible Blends of Tosylated Poly(ethylene glycol) and a Benzoxazine Monomer

The solubility, polymerization, and the macromolecular structure of cured blends of BPA-based benzoxazine (BA-a) in end-group tosylated poly­(ethylene glycol) (mPEGOTs) are studied and compared to analogues from hydroxyl-terminated poly­(ethylene glycol). BA-a can be homogeneously dispersed in both polymers where a wide loading range of ∼100–40 wt % BA-a is possible. The cure temperature for blended BA-a/mPEGOTs was up to 50 °C less than that of pure BA-a or mPEGOH blends. It is proposed that nucleophilic attack of BA-a on the end-group of mPEGOTs produces free tosylate and cationic BA-a-based initiators that act as cure catalystswhere the former was detected by TGA-FTIR and TGA-MS. H-NMR and FTIR revealed the polybenzoxazine (PBA-a) synthesized in mPEGOTs consists of a phenolic rich molecular structure with H-bonded hydroxyl residues and grafted PEG-chains. SEM confirmed that this material, P­(BA-a)-graft-mPEGOTs, has a homogeneous microstructure. The glass transition and the thermal stability of the P­(BA-a)-graft-mPEGOTs can be tuned based on the blend composition.