Synthesis of oligostyrene-b-polyisobutylene via cationic polymerization with sequential monomer addition, starting either from isobutylene and switching to styrene or vice versa becomes increasingly difficult as the degree of polymerization of the styrene block decreases.  Difficulties include the unfavourable crossover rate relative to the polymerization rate of the styrenic monomer when starting from isobutylene and crossing over to styrene and decomposition of the polystyrene living centers at high styrene conversion when starting from styrene and crossing over to isobutylene.We therefore have developed a new synthetic method toward oligostyrene-b-polyisobutylene (OS-b-PIB) as follows.  Oligostyrene (Mn= 600 g/mol, PDI = 1.1) was synthesized first via living carbocationic polymerization (LCCP) using n-hexane/methyl chloride (50:50 v/v) solvent mixtures at -70�C using 1-chloro-1-(p-methylphenyl)ethane as initiator and TiCl4 as co-initiator.  The oligostyrene was then used as a macroinitiator for the polymerization of isobutylene to generate the OS-b-PIB block copolymer.  Block copolymers created by this method have been extensively characterized via GPC, NMR, and MALDI-TOF spectroscopy.  This proposed method can also be used for longer polystyrene chains.

Synthesis and characterization of oligostyrene-b-polyisobutylene block copolymer via oligostyrene macroinitiator

248th National Meeting (2014)

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