Copolymers, block copolymers, and stimuli-sensitive polymers

When only one type of monomer is used for polymerization, the resultant polymer consisting of the same repeating unit is called a “homopolymer.” If polymerization is carried out with two different types of monomers (i.e., copolymerization), the polymer is known as a copolymer. When three different types of monomers are incorporated in the same chain, the term “terpolymer” is often used. It is noted that a copolymer is not a mixture of different homopolymers. In addition to traditional synthetic methods for copolymers (Figure 3.1), various novel synthetic methods have been developed to provide better control on the structures and properties of the copolymers. By combining two or more monomers into one polymer chain, it is possible to obtain a new polymer with better properties than those of the individual homopolymers. Because of such flexibility in producing polymers with new properties, copolymers have been widely studied for their syntheses, characterizations, mechanical behavior, and applications.