synergistic catalysis in polyurethane production: amine catalysts and metal catalysts – a technological review abstract: polyurethane (pu) production hinges on the precise control of two crucial reactions: isocyanate-polyol reaction (gelation) and isocyanate-water reaction (blowing). achieving a balanced interplay between these reactions is essential for optimal pu foam properties. traditionally, amine catalysts have been the workhorse...