Polyurethane polymers were started by Otto Bayer and his co-workers in the laboratories of I.G. Farben in Leverkusen, Germany in 1937. They recognized producing polyurethanes from liquid diisocyanates and liquid polyether or polyester diols by using the polyaddition principle seemed to point to special opportunities, especially when compared to already existing plastics that were made by polymerizing olefins, or by polycondensation. The new monomer combination also circumvented existing patents obtained by Wallace Carothers on polyesters. The polyisocyanates  became commercially available until 1952. Commercial production of flexible polyurethane foam began in 1954, which was based on toluene diisocyanate (TDI) and polyester polyols. The invention of these foams was due to water accidentally introduced in the reaction mix. These materials were also used to produce rigid foams, gum rubber, and elastomers. The first commercially available polyether polyol was introduced by DuPont by polymerizing tetrahydrofuran in 1956. In 1967, urethane modified polyisocyanurate rigid foams were introduced, offering even better thermal stability and flammability resistance to low density insulation products. Automotive interior safety components, such as instrument and door panels were produced by back-filling thermoplastic skins with semi-rigid foam during the 1960s.

Polyurethane RIM evolved into a number of different products and processes using diamine chain extenders and trimerization technology. Further improvements in flexural modulus were obtained by incorporating preplaced glass mats into the RIM mold cavity, which was also known as SRIM or structural RIM. Water-blown microcellular flexible foam was used to mold gaskets for panel and radial seal air filters in the automotive industry starting in the early 1980s. Partly due to the rising costs of petrochemical feedstocks and partially due to an enhanced public desire for environmentally friendly green products, the use of polyols derived from vegetable oils to make polyurethane products began garnishing attention beginning around 2004.