Polymerisation: build a chain by addition or condensation and see what each monomer keeps or loses, then change chain length and branching in an addition polymer

Some polymers grow by throwing atoms away

An addition polymer forms when the C=C double bond in each monomer opens and the monomers link up, keeping every atom. A condensation polymer forms when two functional groups join and a small molecule, usually water, is lost at every link. Pick a monomer, then raise the number of monomers joined and watch what is left over.

Build a chain Addition · 4 units
Pick a monomer. Add units. Watch what is released.
Pick a monomer: addition (C=C) or condensation (two functional groups)
4 ethene → chain · nothing lost
Monomers joined4
Chain molar mass
112.2 g/mol
Water released
0 H₂O
Design an addition polymer Close-packed
Choose a side group. Change chain length and branching. Watch the packing.
Monomer (sets the side group)
Few branches · chains pack closely
Chain length10 000 units
Branches per 1000 C3

Molar mass of one chain
280 500 g/mol
Branches per chain
60
Take it further

Know This

Addition polymers keep every atom as each C=C bond opens, while condensation polymers join two functional groups and lose a small molecule such as water at every link.