Carbonization behavior of iodinated poly(vinyl alcohol)

In this paper, the author reports the role of iodine treatment in the carbonization of poly(vinyl alcohol) (PVA) and preparation of carbon fibers from PVA fiber. PVA can be converted to carbon materials with the assistance of iodine-vapor or iodinesolution treatment at around 90 °C. Iodine acts as a dehydrating agent to withdraw water molecules from PVA chains leading to the generation of polyenes. Furthermore, iodine promotes the formation of a polycyclic aromatic structure by the intermolecular crosslinking reaction of polyenes and the dehydropolymerization of the polycyclic rings formed. Consequently, the carbonization yield of iodinated PVA is extremely increased (ca. 40–50 wt% of the original PVA weight), while uniodinated PVA exhibits only several percent to near zero. The preparation conditions of carbon fibers from iodinated PVA are described in detail. A unique method for the preparation of a hollow carbon fiber, which is produced from a solid PVA fiber precursor by selective iodination within the fiber cross-section close to the fiber surface, is also mentioned.