Polyurethane hot melt adhesives (PU-HMAs) are essential in various industries due to their fast-setting properties, strong adhesion, and versatility across a wide range of substrates. However, conventional fossil-based PUHMAs face significant challenges, including reliance on non-renewable resources, high environmental impact, and the use of hazardous isocyanates, which pose health and safety concerns. To address these issues, this study focuses on developing sustainable, high-performance PHU-HMAs containing pendant furyl groups for metal bonding. A series of adhesives were developed utilizing varying proportions of two biobased dicarbonates derived from lignin and sugar: one featuring a pendant furyl group (BGF-PF-DC) and another without the pendant group (BGF-DC), in conjunction with Priamine 1074. The study comprehensively examined the effects of these formulations on the physio-mechanical, thermal, and adhesive properties. The results demonstrated an impressive renewable carbon content of 89-90 %, high adhesion strength of up to 9.27 MPa on aluminum and 9.43 MPa on stainless steel, excellent underwater adhesion, and outstanding reusability. Furthermore, the postmodifiability of pendant furyl in PHU6-PF100 was evaluated through cross-linking via the Diels-Alder reaction with bismaleimides (BMI). This study also examined the effects of these modifications on both the adhesive performance and thermal characteristics of the modified PHUs. However, the postmodified PHU/BMI network showed a decrease in adhesion but exhibited a higher glass transition temperature and improved adhesion stability at 50 degrees C compared to PHU6-PF100. This study emphasizes the sustainable and high-performance potential of PHU-based hot melt adhesives, establishing them as a viable alternative to traditional isocyanate-based systems. Furthermore, it introduces new opportunities for incorporating Diels-Alder (DA) chemistry into PHU adhesives, which allows for stable adhesion at elevated temperatures and broadens their applicability across various industries. Additionally, this research can serve as a foundation for future studies to investigate thermoreversibility in thermosetting PHUs, potentially expanding their range of applications even further.

Foreign