'HyperMacs to HyperBlocks : a novel class of branched thermoplastic elastomer. ', Macromolecules., 42 (22).pp. 8675-8687. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Corresponding author e-mail: l.r.hutchings@durham.ac.uk RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to)ABSTRACT. We demonstrate here the great versatility of the macromonomer approach for the synthesis of long chain hyperbranched polymers (HyperMacs) and describe the synthesis of HyperMacs from polybutadiene and poly(methyl methacrylate) using analogous yet modified synthetic strategies.Furthermore we report the synthesis, morphology and mechanical properties of an entirely new class of HyperMacs -HyperBlocks -prepared from the coupling of polystyrene -polyisoprene -polystyrene triblock copolymer macromonomers. Transmission electron microscopy (TEM) studies show that these unconventional block copolymers undergo microphase separation but the resulting morphologies lack any long range order. Tensile testing shows that these materials offer promise as a new class of branched thermoplastic elastomer (TPE). Finally blends of HyperBlock (10%) with a commercial linear TPE produced by Kraton, show both enhanced ultimate tensile stress AND elongation at break.2
. (2008) 'HyperMacs long chain hyperbranched polymers : a dramatically improved synthesis and qualitative rheological analysis.', European polymer journal., 44 (3). pp. 665-676. Further information on publisher's website:http://dx.doi.org/10. 1016/j.eurpolymj.2007.12.022 Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in European Polymer Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in European Polymer Journal, 44, 3, March 2008, 10.1016/j.eurpolymj.2007 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract.We have previously reported a novel (albeit modestly successful) strategy for the synthesis of polystyrene HyperMacs -long chain branched analogues of hyperbranched polymers.The building blocks for HyperMacs, AB 2 macromonomers are synthesized by living anionic polymerization and as such are well-defined in terms of molecular weight and polydispersity but the nature of the coupling reaction used to generate the highly branched HyperMacs results in branched polymers with a distribution of molecular weights and architectures. In our previously reported studies the extent of the coupling reaction was significantly hampered by side reactions, however, we report here dramatic improvements to the coupling chemistry which overcome the previously experienced limitations resulting in a four fold increase in the extent of the coupling reactions.Furthermore we report the effect of the addition of varying amounts of a B 3 core molecule to the coupling reaction and the resultant 'control' of the final molecular weight of the HyperMac. Melt rheology showed polystyrene HyperMacs to be thermorheologically simple, obeying WilliamLandel-Ferry (WLF) behaviour. HyperMacs showed little evidence for relaxation by reptation and when the molecular weight of the macromonomer was ≤ M e for polystyrene, HyperMacs resemble unentangled polymers below the gel point, despite being well above the entanglement molecular weight for linear polystyrene. Increasing the molecular weight of the macromonomer to substantially above Me seems to introduce some entangled nature to the HyperMac as evidenced by the emergence of a near horizontal plateau in G'' -the loss modulus.
A facile route to synthesize well‐defined polybutadiene (PBd) DendriMacs is described. In a highly modified approach to that recently published for the synthesis of polystyrene DendriMacs, a G1 polybutadiene (PBd) DendriMac has been synthesized in three simple and high yielding steps. The first step involves the synthesis of a three‐arm PBd mikto arm star in which one arm has a terminal hydroxy group introduced by the use of a protected functionalized initiator. Following fractionation of the star, the hydroxy group is deprotected and converted into an alkyl bromide moiety before coupling the star to a trifunctional core (1,1,1‐tris(4‐hydroxylphenyl)ethane) by a Williamson coupling reaction catalyzed by cesium carbonate to yield a G1 PBd DendriMac.
Sequence control in synthetic polymers is a subject that is sparsely reported with little research in the field of sequence control in chain growth polymerisation. We report herein preliminary investigations into anionic copolymerisation of diphenylethylene (DPE) and its derivatives with styrene. DPE is a monomer that will only copolymerise and can form alternating copolymers. However, by introducing electron donating or withdrawing substituents onto the phenyl rings of DPE it is possible to prepare new range of (alternating) copolymers and with careful choice of monomer combination and conditions, the kinetically controlled (simultaneous) copolymerisation of three or more monomers results in copolymers with a greater degree of monomer sequence control.
Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in ACS macro letters, copyright c American Chemical Society after peer review and technical editing by the publisher. ACS macro letters.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.
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