Conventional polyurethanes involve the use of isocyanates, which require hazardous and toxic phosgene for their manufacture. These monomers cannot be manufactured without elaborate safety devices and huge investment. Isocyanates are also considerably toxic and moisture sensitive. Growing global awareness of the need to protect our environment and continually strive to ensure the safety, health and well-being of those in the industry and consumers has created a demand for environment-friendly products. The cyclic carbonateprimary amine addition reaction which results in hydroxyurethanes is a unique reaction and has been extensively studied over the last few years. This chemistry is now attracting research interest due to its potential application in the preparation of ''green'', non-porous, moisture-insensitive, isocyanate free polyurethanes. This review focuses on catalysis, the mechanism involved in the formation of Non-Isocyanate Polyurethanes (NIPU) from five-membered cyclic carbonates and the reaction kinetics for their synthesis. The higher homologues of the cyclic carbonate family, the six-membered cyclic carbonates, are similar to, but more reactive than, the fivemembered cyclic carbonates and can also serve as a source for production of isocyanate free polyurethanes. This review also summarizes various application of NIPU in coatings, composites, construction and biochemical fields.

Polyurethane is a versatile material that can be converted into various forms according to applications. PU foams or PUFs are the most commonly used polyurethanes. These are materials of low density and low thermal conductivity that make them highly suitable for thermal insulating applications. Most of the synthesis of PUFs is still based on the petrochemical industry. There are issues associated with the oil industry, such as environmental pollution, sustainability, and market instability. More recently, we have experienced the COVID-19 pandemic which has destroyed the global supply chain of raw materials. Such sudden disruption of the supply chain affects the global economy. To eliminate the reliance on special ingredients, it is important to find and produce alternate and domestic raw materials. Vegetable oils are organic, cost-effective, and economically viable and present in abundant amounts. The oil consists of triglycerides. It can be functionalized to provide polyol for PU foam synthesis. Herein, we review the literature on factors influencing the properties of PUFs depending on polyols from vegetable oil as well as present a glimpse of the conversion of vegetable oils into polyols for PUF synthesis.

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