Editing Polyurea (section)

==Polymer structure==

[[File:Polyurea-components.png|thumb|334px|General reaction for forming a polyurea chain, illustrating the two monomer reactants and highlighting the urea linkage in the product]]

The word polyurea is derived from the Greek words πολυ- - poly- meaning "many"; and ουρίας - oûron meaning "to urinate" (referring to the substance [[urea]], found in [[urine]]). Urea or [[carbamide]] is an [[organic compound]] with the chemical formula (NH<sub>2</sub>)<sub>2</sub>CO. The [[molecule]] has two amine groups (–NH<sub>2</sub>) joined by a [[carbonyl]] [[functional group]] (C=O). In a polyurea, alternating [[monomer]] units of isocyanates and amines react with each other to form urea linkages. Ureas can also be formed from the reaction of isocyanates and water which forms a [[carbamic acid]] intermediate. This acid quickly decomposes by splitting off [[carbon dioxide]] and leaving behind an amine. This amine then reacts with another isocyanate group to form the polyurea linkage. This two step reaction is used to make what is commonly but improperly called polyurethane foam. The carbon dioxide that is liberated in this reaction is the primary blowing (foaming) agent especially in many polyurethane foams which more precisely should be called polyurethane/urea foams.