Homopolymers

A homopolymer is a polymer that consists of repeating units derived from a single type of monomer. This distinguishes it from copolymers, which incorporate two or more different monomers in the chain. The term applies to both natural and synthetic polymers.

Most homopolymers form by polymerization of one monomer, through chain-growth (addition) polymerization or step-growth processes. The properties of a homopolymer are largely determined by the structure of the monomer and by the arrangement of the repeating units along the chain, including branching and stereochemistry.

Chain arrangement and tacticity influence crystallinity and thermal behavior. Linear chains with regular stereochemistry can crystallize, while random or irregular arrangements tend to be more amorphous. In particular, isotactic and syndiotactic homopolymers are more likely to form crystalline regions, whereas atactic forms are usually amorphous.

Examples and applications. Common homopolymers include polyethylene (from ethylene), polypropylene (from propene), polyvinyl chloride (from vinyl chloride), polystyrene (from styrene), and poly(methyl methacrylate) (from methyl methacrylate). These materials are used in a wide range of applications, from packaging and construction to electronics and consumer goods.

Relation to copolymers. Compared with copolymers, homopolymers have a uniform composition, which can simplify synthesis and influence properties such as crystallinity, stiffness, and solvent resistance. In many cases, properties are further tailored by blending with other polymers or by incorporating additives.