LIVING CARBOCATIONIC POLYMERIZATION .56. POLYISOBUTYLENE-CONTAINING BLOCK POLYMERS BY SEQUENTIAL MONOMER ADDITION .8. SYNTHESIS, CHARACTERIZATION, AND PHYSICAL-PROPERTIES OF POLY(INDENE-B-ISOBUTYLENE-B-INDENE) THERMOPLASTIC ELASTOMERS

Novel thermoplastic elastomers (TPEs) containing a central rubbery polyisobutylene (PIB) and glassy outer polyindene (PIn) segments have been prepared by living carbocationic polymerization by sequential monomer addition. The synthesis conditions for TPEs were developed with the help of model experiments using the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4 initiating system and subsequent PIn-b-PIB-b-PIn triblock syntheses. Triblock copolymer compositions were determined by H-1 NMR and UV spectroscopy. The structural purity of the triblocks was determined by GPC, and the compositional purity was determined by selective solvent extraction. Characterization of triblocks by DSC, DMTA, and transmission electron microscopy (TEM) indicated a microphase-separated system. The thermal characterization of materials by TGA and melt viscosity versus shear rate indicated good thermal stability and ease of melt processability, respectively. The triblocks exhibited excellent thermoplastic elastomeric characteristics. Tensile strengths, 300% moduli, and hardness increased with increasing polyindene (PIn) content, while percent elongations decreased.