Development of ultra-high build self-healing coatings using amino silanized lignin nanocapsules

Abstract

Self-healing coatings were prepared for corrosion inhibition of mild steel by amino Silanization of lignin nano capsules. In-situ polymerization techniques through sonochemical approach was used for preparation of lignin nano capsules. Coatings have been developed using natural healing materials such as combination of lignin and safflower oil and coupling agents i.e APTES in water borne epoxy curing agent. Successful encapsulation of lignin and safflower oil was carried out via in-situ polymerization with the aid of urea–formaldehyde pre-polymer solution in presence of surfactant polyvinyl alcohol (PVA). Further Functionalization of lignin nanocapsules was done by amino Silanization. TEM and FE-SEM images confirm the encapsulation of nano particles and its histogram gives the average particle size distribution of the lignin nano particle and Capsuleas 106 and 146 nm. Total phenolic content of lignin extract were found to be 936 mg GAE/g. Potentio dynamic polarization studies revealed that the current density decreases to minimum of 3.703E-8A/cm2 with increase in weight percentage of lignin in nanocapsules (1.5 wt%) . Electrochemical Impedance spectroscopy showed a maximum impedance value as 6.44E6 for 1.5 wt% LNC coatings. Immersion studies give better corrosion rate for 1.5 wt% LNC coatings when compared to bare and standard coatings.