A convenient laboratory preparation of isotactic polystyrene

Abstract

AbstractReaction conditions for improving the yield of the crystalline fraction of the product obtained on polymerization of styrene with a heterogeneous catalyst system were determined for the purpose of determining the best conditions for copolymerization studies. The best reaction temperature at atmospheric pressure was found to be about 70°C. The initial ratio of triisobutylaluminum to titanium tetrachloride, if above 3: 1, did not influence the yield of isotactic product appreciably. The addition of lithium aluminum hydride to the catalyst resulted in a slight improvement of vield of isotactic polymer. In the titanium trichloride‐triisobutylaluminum catalyst system, preheating the two catalyst components prior to the addition of solvent and monomer led to improved Activity. Polymerization carried out under conditions of minimum swelling resulted in a lesser amount of amorphous product and improved yield of crystalline fraction. This was accomplished by the use of a nonswelling solvent and the controlled addition of monomer. Maintaining triisobutylaluminum concentration above a given level by stepwise addition during the polymerization greatly increased the activity of the catalyst. In the trichloride system, preheating, together with the use of Nujol as a solvent, controlled monomer addition, and stepwise addition of triisobutylaluminum improved the yield from in average of 0.4 to 6.0 g. of polymer per gram of titanium salt.