monofunctional

Monofunctional describes a molecule that has a single functional group capable of participating in a specific chemical reaction. In polymer chemistry, the term denotes monomers that contain one polymerizable group, such as a single vinyl or acrylate group. This is in contrast to difunctional or polyfunctional monomers, which carry two or more polymerizable groups and can form crosslinks, leading to branched or three-dimensional networks.

The presence of monofunctional monomers in a polymerizing system typically limits the maximum achievable molecular weight and acts as a chain terminator. This can reduce gel formation and provide a means to control polymer end groups or the overall architecture of the material. The ratio of monofunctional to multifunctional monomers, along with reaction conditions, determines whether the resulting polymer is linear, branched, or crosslinked.

Common examples of monofunctional monomers include styrene, methyl methacrylate, vinyl acetate, and other monomers that possess a single polymerizable bond. By contrast, difunctional monomers such as diacrylates or diepoxides contain two reactive sites and are used to promote crosslinking and network formation.

Beyond polymer science, monofunctional can also describe reagents that react at a single functional site, enabling selective modification of a molecule or the introduction of a single reactive end group. The term thus highlights the number of reactive sites and the resulting implications for reactivity, polymer architecture, and material properties.