Comparatively Speaking: Homopolymer vs. Periodic vs. Statistical Copolymers

Monomers within a copolymer may be organized along the backbone in a variety of ways.

Homopolymer copolymers possess alternating single monomer residues, as shown in Line 1 of Figure 1.

Periodic (or block) copolymers have monomer residue types arranged in a repeating sequence. Line 2 of Figure 1 is representative of an alternating or periodic polymer.

Statistical (or random) copolymers have monomer residues arranged according to a known statistical rule. A statistical copolymer, in which the probability of finding a particular type of monomer residue at an particular point in the chain is independent of the types of surrounding monomer residue, may be referred to as a truly random copolymer, as shown in Line 3 of Figure 1.

Block copolymers have two or more homopolymer subunits linked by covalent bonds. Polymers with two or three blocks of two distinct chemical species (e.g., A and B) are called diblock copolymers and triblock copolymers, respectively. Polymers with three blocks, each of a different chemical species (e.g., A, B and C) are termed triblock terpolymers, as shown in Line 4 of Figure 1.

Graft or grafted copolymers contain side chains that have a different composition or configuration than the main chain, as shown in Line 5 of Figure 1.

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