Synthesis, characterization and end-functionalization of a novel telechelic star: styrene hexamer core carrying polyisob
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Synthesis, characterization and end‑functionalization of a novel telechelic star: styrene hexamer core carrying polyisobutylene arms fitted with allyl termini Turgut Nugay1,2 · Nihan Nugay1,2 · Joseph P. Kennedy2 Received: 29 August 2019 / Revised: 29 October 2019 / Accepted: 26 November 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract The synthesis and characterization of a new star consisting of a hard styrene hexamer (St6) core of which emanate long soft polyisobutylene (PIB) arms and fitted with allyl (A) termini is documented. The synthesis was accomplished by a corefirst 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 (Mn = 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 1H 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. Keywords Anionic-to-cationic site transformation · Star polyisobutylene · Furantelechelic polyisobutylene star
Introduction The principal objective of macromolecular engineering is the creation of novel polymeric materials. Using living carbocationic polymerization of isobutylene, well-defined useful materials were prepared and the synthesis of numerous functional and sequential polymers employing this technique were documented [1–8]. This publication concerns * Turgut Nugay [email protected] 1
Department of Chemistry, Polymer Research Center, Bogazici University, 34342 Istanbul, Turkey
2
Department of Polymer Science, The University of Akron, Akron, OH 44325‑3909, USA
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star polymers that are of great scientific and practical interest for a variety of applications, i.e., for the immobilization of cells, drugs, enzymes, or antibodies, and for thermoplastics and nanoelectronics [9]. Combinations of living techniques (termed site transformation strategies) are well suited for the preparation of complex structures and are frequently used for the synthesis of well-defined block polymers [10, 11]. A thorough examination of the site transformation literature revealed only very few references relative to the synthesis of polyisobutylene (PIB)-containing sequential polymers. Thus, Hatada et al. [12] prepared PMMA-b-PIB-b-PMMA triblocks starting with hydroxyl-telechelic PIB (HO-PIB-OH) made by living cationic polymerization, reacted it with acetyl chloride, lithiated the termini with lithium diisopropylamide, and used the macroanions to initiate living anionic polymerization of methyl methacrylate. Similarly, Feldthusen et al.
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