Cambridge O Level Chemistry · Syllabus 5070 · Organic Chemistry
Addition Polymerisation
What is Addition Polymerisation?
The joining together of many unsaturated monomer molecules, in which each carbon-carbon double bond opens to form single bonds to neighbouring units, so that the polymer is the only product and no small molecule is released.
This definition is part of the Organic Chemistry chapter in Cambridge O Level Chemistry.
Addition Polymerisation in context
A homologous series is a family of organic compounds that share the same functional group and the same general formula, whose successive members differ by a -CH2- unit and show a gradual trend in physical properties with similar chemical properties. Alkanes (CnH2n+2) are saturated hydrocarbons with only single bonds and limited reactivity; alkenes (CnH2n) are unsaturated, containing a reactive C=C double bond; alcohols (CnH2n+1OH) contain -OH; and carboxylic acids (CnH2n+1COOH) contain -COOH and behave as acids. Substitution replaces one atom and displaces another; addition opens a double bond to form a single product; condensation polymerisation releases a small molecule at each linkage, while addition polymerisation releases nothing.
Common mistakes with Addition Polymerisation
- “All polymerisation reactions release water.” why it fails This over-generalises from condensation polymers to every polymer. correct Addition polymerisation releases nothing at all — the polymer is the only product. Condensation polymerisation releases a small molecule, and you can only say which one by looking at the functional groups actually being joined. Taught in 11.8B.
Questions students ask about Addition Polymerisation
What is the difference between addition polymerisation and condensation polymerisation?
Addition polymerisation joins many unsaturated monomers by opening each C=C double bond, so the polymer is the only product and nothing is released. Condensation polymerisation joins monomers that each carry two functional groups, releasing a small molecule — usually water — at every linkage formed. A polyamide forms a -CO-NH- linkage from a dicarboxylic acid and a diamine; a polyester forms a -CO-O- linkage from a dicarboxylic acid and a diol.