Parthasarathi Bandyopadhyay

Novel hydroxylated boron nitride functionalized p-phenylenediamine-grafted graphene: An excellent filler for enhancing the barrier properties of polyurethane

A hydroxylated boron nitride (BN(OH)x) functionalized p-phenylenediamine modified reduced graphene oxide (rGO) filler (BN(OH)x–PrGO) is synthesized for the first time using a facile and novel strategy. BN(OH)x–PrGO/polyurethane (PU) composite films are prepared using different filler loadings via a solution casting technique. BN(OH)x–rGO/PU and BN(OH)x/PU composite films are also prepared in order to compare the reinforcing effects of different fillers. FESEM and TEM analyses show the excellent dispersion and compatibility of BN(OH)x–PrGO sheets in the PU matrix. The tensile strength and modulus of the composite film show 62% and 95% enhancement, respectively, following the inclusion of 3 wt% BN(OH)x–PrGO compared to those of the pure PU film. The BN(OH)x–PrGO/PU composite films exhibit outstanding oxygen gas barrier properties, ideal dielectric properties, and excellent anti-corrosion performances. In particular, the 3BN(OH)x–PrGO/PU film shows nearly 91% reduction in the O2 transmission rate compared to the PU film. The permeability of O2 through the composite film is correlated with the diffusivity, solubility and Bharadwaj model. The dielectric constant (at 103 Hz) increases from 6.8 for the pure PU film to 13.1 for the 3BN(OH)x–PrGO/PU composite, and the dielectric loss also remains low for the composite. The potentiodynamic polarization curve shows a substantial shift of the corrosion potential of 3BN(OH)x–PrGO/PU-coated steel towards the anodic direction compared to the PU film, and it exhibits an ultralow corrosion rate (6.14 × 10−5 mm per year) and excellent corrosion inhibition efficiency (99.96%) in saline solution.