Green Chemistry Challenge: 2021 Academic Award

Clemson University

Nonisocyanate polyurethane (NIPU) foam

A team led by Professor Srikanth Pilla of Clemson University is being recognized for creating the first lignin-based nonisocyanate polyurethane (NIPU) foam. This new technology replaces traditional polyurethane foams, one of the most commonly used plastics in the industry. Traditional polyurethane foams are typically manufactured from diisocyanates, a known carcinogen that has significant health and safety effects in its manufacturing.

Summary of Technology:

While the lignin-based NIPU foams have the same mechanical properties as traditional polyurethane foams, they are specifically designed for chemical recycling at their end of life. Clemson University’s innovation uses lignin directly to bypass fractionation and purification steps that typically complicate a sustainable application. The Clemson team first created a reactive, carbonated lignin precursor by using organic carbonates as a reagent. The application of organic carbonates creates a unique opportunity to break down the polymer structure and regenerate the lignin by creating “molecular zippers.” These zippers break down the structure of the foam and recover the lignin. Recycled lignin can be readily used to create a new NIPU foam. The sustainability of the process is also enhanced by the ability to recycle the catalyst (e.g., potassium carbonate) used in multiple synthetic steps. The true innovation of this chemistry lies in the formation of reactive precursors using non-toxic and 100 percent biobased reagents. In the past, lignin has been made into a reactive precursor using oxypropylation with propylene oxide and added diisocyanates to mimic the synthesis of conventional polyurethane foams. With the lignin-based NIPU foams, the curing agent is derived from environmentally friendly vegetable oils.

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