Controlled Hydroxyl Functionality of Soybean Oil-Based Polyols for Polyurethane Coatings with Improved Anticorrosion Properties

Abstract

One of the major challenges in current polymer industry is to develop renewable and sustainable alternatives to petroleum-based raw materials. In this study, soybean oil (SO) was adopted as a renewable resource to afford polyols (MSO) with predetermined primary hydroxyl values (OHVs). The MSOs were prepared through a simple thiol-ene click reaction between the SO and 2-mercaptoethanol. The OHVs of the MSOs were adjusted simply by controlling the conversion of carbon-carbon double bonds of SO to OH groups. To explore their potential applications, series of polyurethane (PU) coatings were prepared from the MSOs. The MSOs with increased OHVs afforded PU coatings with higher glass transition temperature and improved adhesion strength values. Notably, increased OHVs of MSOs afforded PU coatings with improved anticorrosion properties in 3.5 wt% NaCl corrosive medium, which was attributed to the strong adhesion and blocking characteristics of the PU coatings. This study demonstrated that the number of hydroxyl functionality of the bio-based polyols played a crucial role in controlling the characteristics of the PU coatings.