Which polymer family is formed by diisocyanate and a hydroxylic compound?

• A. Polyurethane
• B. Polysulfide Rubber
• C. Polyethylene
• D. Polyamide

Answer: (A)

Polyurethanes form when a diisocyanate reacts with a hydroxylic compound, creating urethane linkages. The isocyanate groups (-N=C=O) react with hydroxyl groups (-OH) on a polyol, linking units together and building a polymer chain. Because the diisocyanate has two reactive ends and the polyol has multiple hydroxyl sites, the reaction extends into long chains and can crosslink, giving a versatile range of materials from flexible foams to rigid plastics. This chemistry is distinct from polyethylene, which comes from simple carbon–carbon linking of ethylene; polyamides, which form amide bonds from diamines and diacids; and polysulfide rubbers, which rely on sulfur-containing linkages.