Synthesis, characterization and end-functionalization of a novel telechelic star: styrene hexamer core carrying polyisobutylene arms fitted with allyl termini

The synthesis and characterization of a new star consisting of a hard styrene hexamer (St(6)) core of which emanate long soft polyisobutylene (PIB) arms and fitted with allyl (A) termini is documented. The synthesis was accomplished by a core-first strategy in two steps: (a) creating the core by living anionic hexamerization of 3-(2-methoxyisopropyl)styrene in essentially quantitative conversion with nearly targeted molar mass (M-n = 1450 g/mol) of very low dispersity (1.06), and (b) using this hexamer to produce in one pot PIB-A arms by living cationic polymerization of isobutylene (> 99% conversion), and terminating with allyltrimethylsilane. This is the first example of a star synthesis by anionic-to-cationic site transformation. Intermediates and final products were characterized by H-1 NMR spectroscopy and GPC according to which the star had 4.61 arms. The star was end-functionalized by thiol-ene clicking with furfuryl mercaptan (85% yield) for the preparation of a furan-telechelic star.