The great chemical affinity of molecular iodine towards several macromolecules
and innumerable polymers allows the formation of macromolecule/polymer-iodine complexes,
usually commensurate with the desired uses and applications. In many instances, the formation
of such complexes occurs through a charge-transfer mechanism. The strength of the
ensued complex is more accentuated by the presence of heteroatoms (nitrogen, oxygen, sulfur)
and the π-conjugation induced moieties within the chemical structure of the polymer. A
wide range of polymers with high specific surface areas and large total pore volumes are excellent
candidates for iodine adsorption, suggesting their use in the removal of radioactive
iodine in nuclear power plants. The recent results of iodine uptake by polysaccharides such
as starch, chitin, chitosan, alginate, and cellulose are but novelties. Complexing vinyl polymers
such as poly(N-vinyl-2-pyrrolidone), poly(vinyl pyridine), poly(vinyl alcohol),
poly(vinyl chloride), poly(acrylonitrile), and polyacrylics, with molecular iodine revealed
special chemistry, giving rise to polyiodide ions (In
-) as the actual complexing agents. Carbon
allotropes (graphene, graphene oxide, carbon nanotubes, amorphous carbons) and polyhydrocarbons
are prone to interact with molecular iodine. The treatment of a broad set of
polymers and macromolecules with molecular iodine is but a doping process that ends up
with useful materials of enhanced properties such conductivity (electrical, ionic, thermal); in
some cases, the obtained materials were of engineering applications. Complexation and doping
materials with iodine are also aimed at ensuring the antimicrobial activity, particularly,
for those intended for medical uses. In several cases, the impact of the iodine doping of polymer
is the alteration of its morphology, as is the case of the disruption of the graphitic morphology
of the graphene or graphene oxide.