introduction polyurethane (pu) is a versatile polymer material widely used in various applications, including coatings, adhesives, sealants, elastomers, and foams. its diverse properties arise from the combination of different polyols and isocyanates, which undergo a polymerization reaction to form the urethane linkage (-nh-coo-). beyond the basic urethane reaction, modifying the pu structure with trimerization reactions...