UV resistance, anticorrosion and high toughness bio-based waterborne polyurethane enabled by a Sorbitan monooleate

Abstract

Sorbitan monooleate (SP) is considered to be a promising renewable polyol with unique molecular structures for the development and design of bio-based waterborne polyurethane (WPU) with versatility and excellent mechanical properties. In this study, SP was used as a bio-based polyol in combination with castor oil to design and prepare a series of bio-based WPU with anti-ultraviolet, corrosion resistance and excellent mechanical properties. The influence of the hydroxyl ratios between SP and castor oil on the chemical structures and properties of bio-based WPU dispersions and the resulting WPU films was systematically studied. The resulting WPU films exhibited excellent mechanical properties and thermo-physical properties due to the presence of large amounts of hydrogen bonding and rigid furan ring, and high crosslinking densities. The bio-based WPU films could lift heavy objects 10,330 times their own weight. The resulting WPU coatings could resist ultraviolet radiation in the region (200–400 nm) and exhibited excellent UV resistance in outdoor practical application tests. In addition, these WPU coatings demonstrated effectively anticorrosive effect in which the anticorrosion period of the coating on the tinplate outdoors could be as long as 6 months in terms of corrosion potential, corrosion current and corrosion protection efficiency of the coating reached −0.507 V, 2.92 × 10−6 A, and 95.39%, respectively. This study provides a new and simple method for preparing bio-based WPU with excellent anti-ultraviolet performance, anti-corrosion performance and excellent mechanical properties.