Three difunctional fluorene-based benzoxazine compounds were synthesized via Mannich condensation and were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR), and elementary analysis (EA). The polymerization of benzoxazine monomers were investigated with differential scanning calorimeter (DSC) method. Thermal properties of the polybenzoxazines were studied by thermogravimetric analysis (TGA) and DSC. Water absorption of the polybenzoxazines was tested. Contact angle measurement was employed to characterize the surface property of materials. The glass transition temperatures (Tgs) and thermal stability were improved significantly in comparison with bisphenol-A-based analogue because of the incorporation of rigid fluorenyl group. The fluorenyl-based polybenzoxazines showed hydrophobic characteristics, which was ascribed to the low polarity of fluorenyl and pipi stacking interaction of fluorenyl on the surface. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers