Thermally mendable and improved hydrophilic bioepoxy/PEG-PPG-PEG blends for coating application

Abstract

Self-healing bio-based epoxy blends of poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), (PEG-PPG-PEG) triblock copolymer (TBCP) was prepared and investigated, with the goal of developing smart self-healing coatings that can protect metal surface from corrosion. The epoxy blends consist of low molecular weight triblock copolymer (L61) blended in different weight percentage (5, 10, 20, 30, 40 and 50 wt%) were prepared. A room temperature curing agent was selected and the thermal mending of bioepoxy coatings are investigated. At an elevated temperature (ca.140 °C–150 °C), the TBCP phase undergoes mending and migrate to the crack site, forming a thin layer of protective coating on the substrate (carbon steel). The system was transparent up to 5 wt% TBCP content and are opaque above 10 wt% TBCP concentrations. The contact angle reduced considerably from 72.5° to 25.5° due to the hydrophilic nature of TBCP. The thermal stability was increased, while the mechanical properties were decreased by the addition of TBCP.