Polycondensation is step-growth polymerization in which joining reactions eliminate small molecules. Its chain-bearing molecule count excludes those byproducts; otherwise two chains joining while releasing one small product would misleadingly appear to conserve the counted population.[ref]
IUPAC Compendium of Chemical Terminology, fifth edition (Gold Book) by International Union of Pure and Applied Chemistry. polycondensation, P04722, definition and growth-step equation
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