Cutting-Edge Development of Non-Isocyanate Polyurethane (NIPU) Foams: From Sustainable Precursors to Environmental Impact Evaluation

Abstract

Polyurethane (PU) foams represent a wide class of polymeric materials, having implications in different sectors from automotive, packaging, cushioning/bedding to construction. However, their synthesis requires the use of petrol-based components; mostly harmful and toxic isocyanates. On this account, non-isocyanate polyurethane (NIPU) foams have been indicated as promising alternatives to conventional PUs, being obtained through “isocyanate-free” routes such as aminolysis of cyclic carbonates with diamines. The building blocks of NIPU foams can be derived from many different bio-sources e.g., vegetable oils, sugars and terpenes, and the final material can be fully reprocessed and recycled. This review aims to comprehensively describe the current state of the art concerning the synthesis and applications of NIPU and hybrid NIPU foams and it is divided into three sections: i) outline the synthesis of bio-based NIPU precursors, i.e. cyclic and linear carbonates, diamines and carbamates from bio-based sources and via environmentally-friendly approaches, ii) description of the current state of the art to obtain NIPU and composite NIPU foams including aspects related to their reprocessability and recycling; iii) evaluation of the environmental impacts of NIPU precursors and foams by Life Cycle Assessment (LCA) technique and description of the future perspectives.