Optimization of stability and properties of waterborne polyaniline-graft-poly (vinyl alcohol) nanocomposites with controllable epoxy content

Here, environmental polyaniline graft epoxy-functionalized poly(vinyl alcohol) (PANI-g-EPVA) nanocomposites of enhanced storage stability and performance were obtained by building chemical bonds between PANI and PVA based on graft polymerization, using water as the medium. The performance of PANI-g-EPVA greatly depended on the epoxy content in PVA chains. With the increasing of the epoxy content, the morphology of colloidal particles changed from inhomogeneous spherical morphology to uniform rice-like morphology; the particle size decreased from 1333 to 153.9 nm; the turbiscan stability index (TSI) increased and the increasing rate of TSI dropped by 0.08 with time, certifying the enhanced storage stability. With incorporating appropriate amount of epoxy groups, PANI was able to distribute uniformly in nanocomposites and films with smooth morphology were obtained. As a result, the tensile strength increased from 24 to 64 MPa, the elongation at break rose from 51 to 166%, and the conductivity increased from 0.4 to 7.3 S/cm. The as-prepared waterborne PANI-g-EPVA nanocomposites can be well dispersed in waterborne epoxy resin to produce anticorrosive coatings. Subsequently, the corrosion current density decreased by two orders and the corrosion potential shifted from −0.67 to −0.54 V, demonstrating improved anticorrosive properties.