Study on the synergistic anticorrosion property of a fully bio-based polybenzoxazine copolymer resin.

• The benzoxazine are completely made from bio-based resource. • The corresponding polymer has low dielectric constant and low dielectric loss. • The copolymer showed high protection efficiency as anti-corrosion coating. • This high protection efficiency can owe to the synergistic effect of different benzoxazine. In this paper a novel bio-based benzoxazine, dehydroabietylamine benzoxazine monomer (D-Bz), was synthesized and a series of copolymers were prepared by using D-Bz and two other bio-based benzoxazines 6-allyl-8-methoxy-3-octadecyl-3, 4-dihydro-2H-benzoxazine (S-Bz) and 6-allyl-3 –(furan-2-ylmethl)-8-methoxy-3, 4-dihydro-2H-benzoxazine (F-Bz). The structure, morphology and curing process are characterized by 1H nuclear magnetic resonance spectroscopy (1H NMR), mass spectrometry (MS), fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Electrochemical techniques such as open circuit voltage time (OCPT), Tafel and electrochemical impedance spectra (EIS) were used to study their electrochemical corrosion properties. Results show that among these copolymer, when the ratio of S-Bz: D-Bz: F-Bz is 1:6:3, the copolymer has good synergistic effects, showing a lower dielectric constant (2.47 at 1000 Hz), higher crosslink density (5.29*E−4 mol/ml), lower corrosion current (0.030 µA/cm2) and the best electrochemical corrosion efficiency (99.73%). [ABSTRACT FROM AUTHOR]