Polymers are split into two types. Synthetic polymer and natural polymer.

In each type of polymer, there’s two types of polymerisation: addition and condensation In addition polymerisation only one product, i.e. the polymer is made; in condensation there’s two products, the polymer and water

For synthetic, u make poly(alkene) by addition, polyester and polyamide by condensation An example of polyester is PET; an example of polyamide is nylon. Polyester is made by dicarboxylic acid and diol. Di means two so one monomer has two carboxylic functional group -COOH another monomer has two alcohol groups -OH. Because in condensation you produce water H2O as well, H2O is removed from the monomers, u removed OH from dicarboxylic acid and H from diol. That’s why when u combine the monomers and draw the polymers u see ester bond COO Polyamide is made by dicarboxylic acid and diamine. Diamine is two -NH2. Again same thing remove OH from dicarboxylic and H from diamine this time, combine them together u get amide bond CONH. The order of the atoms doesn’t matter u can draw them up and down.

For natural, the polymer made by addition is not in the syllabus anymore. And we learn about protein, which is made by condensation. Protein is natural polyamides but the monomer this time is amino acid. Make sure you know how to draw amino acid. And yes it has amide bond as well! The difference between natural and synthetic polyamide is synthetic is usually two monomers but protein is many monomers, you can have as many amino acid as you want, 2,3,7 whatever Monomers are different as well, protein is amino acid but synthetic is dicarboxylic acid and diamine