Synthesis, characterization and corrosion protective properties of boron-modified polyurethane from natural polyol

A novel attempt has been made to incorporate boron in the backbone of castor oil to develop boron-modified polyester (BCPE) and polyurethane (BPU). The overall reaction strategy involved “single pot multiple reactions” in minimum solvent achieving about 50% reduction in the use of volatile organic compounds (VOCs) during the synthetic procedure. Spectral (I.R., 1H NMR and 13C NMR), physicochemical and thermal (TGA and DSC) analyses of BCPE and BPU were carried out by standard methods. The physico-mechanical and corrosion/chemical resistance performances (in various corrosive media) tests of BPU coatings were also conducted to evaluate their coating properties. These studies revealed that (i) the incorporation of boron has a significant influence on structural and physico-chemical aspects, thermal stability as well as on coating properties of BPUs, (ii) interestingly, BPUs showed very good performance in alkaline media (unaffected in 5 wt% NaOH for 50 h) as compared to their other previously reported oil-based counterparts, (iii) boron, here, acts both as a modifier and crosslinker and (iv) BPUs serve as novel and promising candidates for use as corrosion protective coating material, which can be safely employed up to 220 °C.