Scale-up precision synthesis of octa-arm polyisobutylene stars

This paper concerns the scale-up precision synthesis of octa-arm polyisobut ylene (PIB) stars. Specifically, we have optimized to the 100-200 g scale t he preparation of star polymers consisting of eight PIE arms radiating from a calix[8]arene core. The synthesis strategy involved the use of a calix[8 ]arene fitted with eight p-C(CH3)(2)OCH3 groups as the initiator in conjunc tion with mixed BCl3/TiCl4 coinitiators in hexanes/methyl chloride solvent systems at - 80 degrees C. Various possible side-reactions have been identi fied and means for their suppression/elimination were developed.