Multifunctional initiators for living isobutylene polymerization

The key to the precision synthesis of polyisobutylene and its derivatives has been the initiating system that leads to well-defined structures. In this chapter, multifunctional (di-,tri-, tetra-, etc. functional) aliphatic and aromatic cationic initiators synthesized and employed to achieve LC+P of isobutylene for the preparation of telechelic PIBs and well-defined PIB derivatives in the past three decades are reviewed. Special attentions are paid on the effect of different functional groups of the initiators, polymerization temperature and solvent system on initiator efficiency, conversion and livingness issues. Some recently discovered multifunctional initiators to synthesize linear and star PIB's are also presented.