Polystyrene-styrene-diethyl ether

To 5.3 g of 4-vinylpyridine is added to THE up to a volume of 50 ml 5 ml of this solution (containing 5 mmol 4-vinyl pyridine) are added in the same way to the above solution containing the "living" polystyrene, with vigorous agitation. After 15 min another 40 mmol of styrene are added, followed 15 min later by another 5 mmol of 4-vinylpyridine this operation is repeated once more. 15 min after the last addition of monomer the block copolymer is precipitated by dropping the solution into a mixture of 300 ml of diethyl ether and 300 ml of petroleum ether.The polymer is filtered, washed with ether,filtered again, and dried in vacuum at room temperature. 

The use of ethers as cocatalysts for the cationic polymerisation of alkenyl monomers induced by Lewis acids has received little systematic attention and the mechanism through which these compounds operate is not well understood. The complex diethyl-ether-boron fluoride has been extensively used as a very convenient cationic initiator, but mostly for preparative purposes. As in the case of alcohols and water, ethers are known to act as inhibitors or retarders in the cationic polymerisation of olefins, if used obove cocatalytic levels, because they are more nucleophilic than most rr-donor monomers. Imoto and Aoki showed that diethyl ether, tetrahydrofuran, -chloro-diethyl ether and diethyl thioether are inhibitors for the polymerisation of styrene-by the complex BF3 EtjO in benzene at 30 °C, at a concentration lower than that of the catalyst, but high enough (0.5 x 10 M) to quench the active species formation for a time. Their action was temporary in that the quenching reaction consumed them, and therefore induction periods were observed, but the DP s of the polystyrenes were independent of the presence of such compounds, as expected from a classical temporary inhibition. 

Methacrylic acid (MAA) was obtained from Aldrich Chemicals with 250 ppm inhibitor of methyl ethyl hydroquinone (MEHQ) without further purification. Styrene also came from Aldrich and was double distilled and inhibited with hydroquinone (HQ) before use. Diethyl ether (DEE) from Aldrich Chemicals was used as it is. Poly(methacrylic acid) (PMAA) made by the FRRPP process in our lab with different molecular weights and polydispersity indices (PDI) was used in the experiments. Polystyrene was bought from Pressure Chemicals Co. with different molecular weights and the same PDI of 1.06. The products through the FRRPP process in our lab were also used to determine the phase envelope. 

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