Pentads

Tetrads, Pentads, etc. The definition of tetrads and pentads introduce further sophistication and precision to defining tacticity, especially when information on long-range ordering is desirable.

Tacticity measurements obtained by Carbon-13 NMR are typically expressed in terms of the relative abundance of various pentads within the polymer molecule, e.g. mmmm, mrrm.

The average meso sequence length may be approximated from the relative abundance of pentads as follows: citation Polymers Isotactic polymers Isotactic polymers are composed of isotactic macromolecules (IUPAC definition).