Depending on how many different monomers are combined into a polymer, and in what order and structure, we have different ways of generally classifying polymers (Table 1.2 in text). If the polymer is made up of a single monomer, we call it a homopolymer (Figure 1.7) (e.g., if our monomer is A, the polymer would be poly(A)). If a polymer is derived from the polymerization of multiple different monomers, we call it a copolymer (Figure 1.8) (e.g., if our monomers are A and B, our polymer would be poly(A-co-B). There are many varieties of copolymers. If the positions of monomers is randomly distributed within the polymer, then we call that poly(A-ran-B). Here, “random” does not mean the same thing as “I didn’t intentionally put the monomers in a specific order”; to be random, there truly has to be a random distribution over the entire length of the polymer, which in many cases does not happen even if you do not intentionally control monomer order. More often, “statistical” is correct; since each monomer may have a different reactivity, one monomer may be more readily incorporated in the polymer than the other and so the distribution of each monomer along the polymer MAY be different. So in the cases where the monomers follow such statistical distributions (that are not random) we call them statistical copolymers, poly(A-stat-B). Figure 1.8 shows drawings of alternating copolymers poly(A-alt-B), block copolymers poly(A-block-B), and graft copolymers polyA-graft-polyB. A blend is a mixture of different polymers.
