In materials engineering, what term describes a class of polymers formed from diisocyanates and polyols?

• A. Urethane
• B. Polystyrene
• C. Ceramics
• D. Polypropylene

Answer: (A)

The question tests recognizing the chemistry of polymers made from two types of starting reactants: diisocyanates and polyols. When a diisocyanate reacts with a polyol, it forms urethane linkages (-NH-CO-O-). This reaction builds a class of polymers known as polyurethanes. The term urethane in this context describes the bonding motif and the family of materials produced, which can range from flexible foams to rigid plastics and coatings depending on the specific reactants and formulation. The other options point to different polymers or materials that aren’t formed from diisocyanates and polyols (polystyrene from styrene, polypropylene from propylene) or are non-polymeric ceramics, so they don’t fit the described synthesis.