Polyurethane based tri-block copolymers namely poly(N-vinylpyrrolidone)-b-polyurethane-b-poly(N-vinylpyrrolidone) (PNVP-PU) and poly(dimethylaminoethylmethacrylate)-b-polyurethane-b-poly(dimethylaminoethylmethacrylate) (PDMAEMA-PU) were synthesized through atom transfer radical polymerization (ATRP) mechanism. The synthesized polymers were characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) methods. The corrosion inhibition performances of the compounds were investigated on mild steel (MS) in 0.5 M H2SO4 medium using electrochemical measurements, surface analysis, quantum chemical calculations and molecular dynamic simulations (MDS). Potentiodynamic polarization (PDP) measurements revealed that the polymers are mixed-type corrosion inhibitors. Electrochemical impedance spectroscopy (EIS) measurements showed that the polymers inhibit MS corrosion by adsorbing on MS surface to form pseudo-capacitive interface. The inhibitive effects of the polymers increase with increasing concentration and decrease with increasing temperature. The adsorption of both the polymers on MS surface obey the Langmuir adsorption isotherm and involves both physisorption and chemisorption mechanisms. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses showed that the polymers formed protective film on MS surface and shield it from direct acid attack. Quantum chemical calculations and molecular dynamic simulations studies corroborate experimental results.

No abstract

Two polyurethane based triblock copolymers, namely, poly(N-isopropylacrylamide)-b-polyurethane-b-poly(N-isopropylacrylamide) (PIA-PU-PIA) and poly(tert-butylacrylate)-b-polyurethane-b-poly(tert-butylacrylate) (PtBA-PU-PtBA), were synthesized via atom transfer radical polymerization (ATRP) mechanism and characterized. The inhibition potentials of the polymers on mild steel corrosion in 0.5 M H 2 SO 4 were studied using electrochemical, scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. The results obtained from potentiodynamic polarization studies showed that the two polymers are mixed-type inhibitors and exhibit passivating activities. The adsorption of PIA-PU-PIA on mild steel surface obeys the Langmuir adsorption isotherm, while that of PtBA-PU-PtBA obeys the El-Awady isotherm. The two polymers adsorb on the mild steel surface via competitive physisorption and chemisorption mechanisms. Both SEM and AFM analyses confirmed the formation of protective layers of the inhibitor molecules on the steel surface. The results obtained showed that PIA-PU-PIA exhibited higher inhibition performance than PtBA-PU-PtBA, and the trend was corroborated by the results obtained from quantum chemical calculations.

No abstract

No abstract

No abstract

No abstract

A new phosphonium salt (4-ethoxybenzyl)-triphenylphosphonium bromide (EBTPPB), having different substituents attached to phosphorous and having different anions, is investigated as an inhibitor for mild steel (MS) corrosion in 0.5 M H 2 SO 4 solutions via electrochemical polarization and electrochemical impedance (EI) spectroscopy. Electrochemical results show that EBTPPB compound has practically good inhibiting features for MS corrosion in the corrosive medium with efficiencies of approximately 98% at an optimum 10 À2 M concentration. The inhibition is of a mixed cathodic-anodic type. Passive potential (E pp ) of the modified steel specimen is in the inactive region and thus inhibits the corrosion process.Langmuir Adsorption (LA) isotherm was performed to provide precise information on the adsorption behavior of the ionic salt. It exhibits both physisorption and predominantly chemisorption mechanism on MS surface. Scanning Electron Microscopy (SEM) associated with Energy Dispersion X-ray (EDX) and Atomic Force Microscopy (AFM) assessment of the electrode surface is consistent with the existence of adsorbing screen of EBTPPB molecules. An apparent connection was ascertained between the experimental corrosion inhibition efficiency (IE%) and the theoretical parameters using quantum chemical calculations.