CH2CX2n
CH2CX2n refers to a class of polymers derived from monomers with the general formula CH2=CX2, where X represents a halogen atom. These polymers are characterized by a repeating unit where a carbon atom is double-bonded to two halogen atoms, and this unit is linked together by single bonds in a long chain. The simplest example is polytetrafluoroethylene (PTFE), commonly known by the brand name Teflon, where X is fluorine (F). In this case, the monomer is tetrafluoroethylene (C2F4), and the polymer repeat unit is -[CF2-CF2]-. Other common examples include polyvinylidene fluoride (PVDF), where X is fluorine (F) and hydrogen (H) in an alternating pattern, and polychlorotrifluoroethylene (PCTFE), where X is fluorine (F) and chlorine (Cl).
These polymers exhibit a range of unique properties due to the presence of halogen atoms, particularly fluorine.