What name is given to polymers formed by reaction of diisocyanates with hydroxyl groups?

• A. Nylon
• B. Urethane
• C. Silicone
• D. Polyethylene

Answer: (B)

Forming polymers by reacting diisocyanates with hydroxyl groups creates urethane linkages. When diisocyanates (which have two reactive -NCO groups) react with polyols (molecules with multiple hydroxyl groups), each reaction forms a urethane bond (carbamate). Linking many of these bonds yields polyurethanes, so the family is often described as urethane-based polymers. That’s why the correct name is urethane (polyurethane): the defining linkage in the chain is a urethane link, produced by the reaction between an isocyanate and a hydroxyl-containing compound. The other options are different polymer chemistries—nylon from diamines and diacids, silicone from siloxane chemistry, and polyethylene from simple olefin addition—so they don’t describe this isocyanate–hydroxyl reaction.