Emerging Trends in Nonisocyanate Polyurethane Foams: A Review

Abstract

Polyurethane foams (PUF) are essential materials known for their exceptional chemical and mechanical properties, making them ubiquitous in a wide range of applications. Conventionally, PUF are produced through polyaddition reactions between polyols and polyisocyanates at room temperature, where water plays a critical role in this process by hydrolyzing the isocyanates, leading to the release of carbon dioxide (CO₂) as a blowing agent. In recent years, isocyanates have raised significant concerns in industries and consumers due to their high toxicity. Therefore, driving the need to explore alternative synthesis routes for PUF that do not involve the use of isocyanates. Nonisocyanate polyurethane foams (NIPUF) derived from the aminolysis of cyclic carbonates have emerged as the most promising solution to replace the conventional method of producing PUF. Despite this, the challenging aspect lies in identifying a suitable foaming strategy for NIPUF that can satisfy both sustainability and performance requirements. In view of this, the first part of this review focuses on the background, chemistry, and challenges of PUF. In the second part, the chemistry of NIPUF and the various foaming strategies used to prepare them are discussed and analyzed. Finally, the outlook and future research focus areas for NIPUF are outlined.