Anionic Polymerization in the Interlayer Spacing of Graphite


National Institute of Advanced Industrial Science and Technology; 1-8-31 Midorigaoka, Ikeda-shi 563-8577 Japan

Stage 1 and 2 potassium-graphite intercalation compounds (GICs) were allowed to react with unsaturated hydrocarbons. After contact with isoprene, styrene or 1,3-butadiene, K-GICs expanded slowly along the c-axis direction. Unsaturated hydrocarbons were introduced into the interlayer spacing of GICs and polymerized progressively. The polymerization is considered to be initiated by the radical-anions of the negatively charged graphite layer of K-GICs. Rubidium-GIC expanded slowly in a similar manner described above. In the case of cesium-GIC, isoprene was polymerized in the similar manner, whereas the reactivities of styrene and 1,3-butadiene were low. The different reactivities are explained on the basis of the activity of polymerization initiators. The degree of charge-transfer from alkali metal to graphite layer in the GIC of K or Rb was higher than that of Cs, which resulted in the higher reactivities of K- and Rb-GICs as a polymerization initiator. The reactivities of monomers for polymerization were in the following order: isoprene > 1,3-butadiene > styrene, which was the reverse order of the reactivities recognized in the conventional polymerization. Isoprene and styrene were polymerized in the interlayer of K-GIC in the presence of organic solvent. Isoprene was introduced into the interlayer, whereupon both aromatic and aliphatic solvents were incorporated into polyisoprene and polymerized. On the other hand, the polymerization of styrene in the interlayer of graphite was accompanied by the incorporation of aromatic solvents, but was not accompanied by the incorporation of aliphatic solvents. This is explained on the basis of the affinity of monomer and graphite layer for solvent. The novel carbon material obtained by a heat treatment of the product from the reaction of K-GIC with isoprene is also discussed.

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