Alpha-Methylstyrene → Disodium alpha-methylstyrene

A polystyrene having carboxyl groups in both terminals was synthesized according to the process described in Y. Yamashita, T. Hane, J. Polym. Sci., Polym. Chem. Ed., 11, 425 (1973). A solution of red disodium α-methylstyrene tetramer in tetrahydrofuran was prepared by reacting α-methylstyrene in tetrahydrofuran at -20° C. in the presence of metal sodium. To the solution was added a solution of styrene in tetrahydrofuran at 0° C., and the resultant mixture was subjected to polymerization with stirring to obtain a solution of disodium polystyrene in tetrahydrofuran. Excess carbon dioxide was blown through the solution to cause reaction at room temperature. Excess carbon dioxide was removed under reduced pressure. The resultant solution was poured into methanol acidified with hydrochloric acid, and the product was lyophilized with benzene to obtain a polystyrene having free carboxyl groups in terminals, which has a number average molecular weight of 7000. When a solution of it in N,N-dimethylformamide to which excess potassium hydroxide was added was subjected to back titration using an aqueous solution of potassium hydrogen phthalate, the number of terminal carboxyl groups was confirmed to be about 2. A solution prepared by dissolving 3.81 g of the resultant polystyrene having carboxyl groups in both terminals in 30 ml of N-methyl-2-pyrrolidone was chilled to 0° C. After addition of 0.2262 g of dicyclohexylcarbodiimide to the resultant solution, it was stirred at 0° C. for 1 hour. To the solution was then added a solution of reduced polyaniline (1 g), and the reaction mixture was stirred for 6 hours while the temperature was raised slowly to room temperature. The reaction mixture was poured into 1 liter of diluted hydrochloric acid with stirring, and resulting precipitate was collected by filtration. After the precipitate was exposed to an ammonia gas and washed with water to remove hydrogen chloride, it was dried to obtain 4.75 g of a cross-linked polyaniline derivative.