Condensation polymers
In condensation polymerisation, monomers with two functional groups join and release a small molecule (H₂O or HCl). Polyesters: diol + dicarboxylic acid (or diacyl chloride), e.g. PET from benzene-1,4-dicarboxylic acid and ethane-1,2-diol, linked by –COO–. Polyamides: diamine + dicarboxylic acid, e.g. nylon-6,6 (hexane-1,6-diamine + hexanedioic acid) and Kevlar, linked by –CONH–; hydrogen bonds between chains give strength. Proteins are natural polyamides. Unlike poly(alkenes), condensation polymers can be hydrolysed at their polar links (acid or alkali), making some biodegradable (e.g. PLA).
≈ 45 min