Benzoxazine Miniemulsions Stabilized with Polymerizable Nonionic Benzoxazine Surfactants

For the first time, the concept of polymerizable nonionic benzoxazine surfactants is described. Different target structures with varying hydrophobic−lipophilic balance (HLB) values were synthesized and successfully tested for the miniemulsification of two N-aliphatic and N-aromatic benzoxazine resins. As a model system, the difunctional benzoxazine surfactant bis(3,4-dihydro-2H-3-(polypropyleneoxide-block-polyethyleneoxide-1,3-benzoxazinyl)isopropane (B2000) was analyzed in detail via FT-IR, 1H NMR, surface tension measurements, and thermal analysis such as DSC and TGA. Additional to the colloidal stability of the benzoxazine miniemulsions, investigations focused on the surfactant copolymerization behavior and compatibility with other resins. It was found that despite the observed slow homopolymerization the described surfactants easily undergo copolymerization with the model benzoxazine resins.