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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Condensation polymer

A polymer formed from monomers carrying two functional groups, where every new link releases a small molecule, usually HX2O\ce{H2O} (or HCl\ce{HCl} from an acid chloride). The backbone contains ester or amide links, and the repeat unit equals the monomers minus the molecules released.

Polymer chain and repeat unitMany ethene monomers (CH₂=CH₂) join into a long polyethylene chain. The repeat unit, –CH₂–CH₂–, is shown in brackets with subscript n for the number of repeats.n CH₂=CH₂ → –[CH₂–CH₂]ₙ–monomer → polymernrepeat unit……each vertex is a CH₂ carbon; n is often 10³–10⁵

Example

PLA forms from lactic acid, CX3HX6OX3\ce{C3H6O3}, which carries both –OH and –COOH. Each link releases one HX2O\ce{H2O}, so the repeat unit is CX3HX4OX2\ce{C3H4O2} (72.06 g/mol).

See alsoAddition polymerPolyesterPolyamideByproduct