Recyclable Hydrophobic Polyurethanes and Debondable Coatings Utilizing Apolar Acetal Polyols

Abstract

Polyurethanes (PUs) are versatile polymers widely used in coatings, elastomers, adhesives, and foams due to their diverse properties. Designing PUs with enhanced functionality and recyclability is essential to developing sustainable materials. In this study, apolar acetal-containing polyols (APs) were developed via a scalable polycondensation process using long-chain aliphatic aldehydes and diols. These APs enabled the straightforward synthesis of PUs with very low surface polarity, low glass transition temperatures, excellent mechanical performance, and high hydrolytic stability. Importantly, the incorporation of cleavable acetal bonds allowed closed-loop recycling of the PUs under mild acidic conditions, enabling high-yield recovery of monomers. To demonstrate their versatility, the APs were used in two-component PU coatings, which exhibited strong adhesion to aluminum, superior hydrophobicity (contact angles >97°), and efficient debonding under environmentally benign conditions. This work underscores the potential of acetal-containing polyols to address environmental challenges by combining innovative material design with sustainable recycling pathways, advancing the development of recyclable PUs for applications in coatings, compact materials, foams, and adhesives.