Well-Defined Comb, Star−Comb, and Comb-on-Comb Polybutadienes by Anionic Polymerization and the Macromonomer Strategy

Koutalas, G.; Iatrou, Hermis; Lohse, David J.; Hadjichristidis, Nikos

doi:10.1021/ma047333r

Cited by 91 publications

(75 citation statements)

References 24 publications

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“…[8,21] The disadvantage hereby is the formation of highly toxic chloromethyl methyl ether during the functionalization reaction, which makes the synthesis of large amounts (several grams) difficult. The synthesis of polyisoprene (PI) and polybutadiene (PBd) model comb homopolymers with a low branching degree can be accomplished by using the macromonomer technique, [23][24][25] lithiation of the backbone, [26] or hydrosilylation [27,28] of pendant vinyl groups of 1,2/3,4 units in PI and 1,2 units in PBd, respectively. In these cases, a low polydispersity of the backbone and the side chains can be achieved by the use of anionic polymerization, [29] but the number of branching points (especially if < 1 mol-%) is difficult to control and to analyze.…”

Section: Introductionmentioning

confidence: 99%

Anionic Synthesis and Rheological Characterization of Poly(p‐methylstyrene) Model Comb Architectures with a Defined and Very Low Degree of Long Chain Branching

Kempf

Barroso

Wilhelm

2010

Macromol. Rapid Commun.

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A method is presented for the synthesis of defined sparsely branched polystyrene-based homopolymer model combs. By the use of poly(p-methylstyrene) (PpMS) as backbone and side chains, a low, but well controlled amount of branching of typically less than 1 mol-% (e.g., 1 branch per approx. 200 backbone C-atoms) can be achieved. The used anionic synthesis offers full control of the molecular weight in combination with low polydispersity. Molecular weight and polydispersity were determined by SEC-MALLS, confirming the well defined synthesis with low polydispersity ($\overline {{\rm M}} _{{\rm w}} /\overline {{\rm M}} _{{\rm n}} $ < 1.07). The melt rheological properties of the synthesized linear and comb polymers were obtained in both oscillatory shear and uniaxial extensional flow. Using the so-called van Gurp-Palmen plot, clear differences between both synthesized topologies are clearly seen. The appearance of a second minimum for lower values of the complex modulus in shear is a clear indication of a second relaxation process attributable to the entangled side chains. The presence of the entangled side chains is responsible for the observed strain hardening obtained in extensional viscosity experiments, as compared to the linear polymers. These model samples open up the possibility to compare different advanced rheological methods, e.g., FT-rheology or extensional rheology, towards limiting sensitivity.

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Section: Introductionmentioning

confidence: 99%

Anionic Synthesis and Rheological Characterization of Poly(p‐methylstyrene) Model Comb Architectures with a Defined and Very Low Degree of Long Chain Branching

Kempf

Barroso

Wilhelm

2010

Macromol. Rapid Commun.

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“…Methods for the synthesis of highly branched polymer architectures using macromonomers as building blocks have subsequently been reported by a number of research groups including graft copolymers [20] and combs/star combs [21]. The advantage of the macromonomer approach in these strategies is the ability to control the molecular weight of the branches/combs independently from the backbone although there is still a certain lack of control in the molecular weight between branch points.…”

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confidence: 99%

HyperMacs – long chain hyperbranched polymers: A dramatically improved synthesis and qualitative rheological analysis

Clarke

Luca

Dodds

et al. 2008

European Polymer Journal

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. (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.

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“…Much of this sort of work has been done on symmetric stars (i.e., equal arm lengths) [124][125][126], as well as stars with various arm lengths made by the miktoarm techniques of Hadjichristidis et al [127][128][129][130]. Some model PE polymers with multiple branch points, including some pom-pom structures [131][132][133][134], combs [135][136][137][138][139], and dendritic polymers [140][141][142][143][144], have also been studied in this regard. All of them have a local structure identical to an LLDPE with 7 to 10 wt% butene (i.e., 2 to 3 ethyl branches per 100 backbone carbons).…”

Section: Lcb In Polyethylenementioning

confidence: 99%

“…Typical synthesis routes to dendritic polymers with a very precise architecture require many steps and high vacuum techniques to avoid poisoning [135][136][137][138][139][140][141][142]. The time and care required for such production makes it quite expensive.…”

Section: Effects Of Lcb On Melt Rheologymentioning

confidence: 99%

The Critical Role of Anionic Polymerization for Advances in the Physics of Polyolefins

Lohse

2015

Anionic Polymerization

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This chapter shows how the great power and versatility of anionic polymerization, which has been described in the rest of this book, has been used to develop an improved understanding of the basic physical principles that underlie the performance of polyolefin materials. When these synthetic tools are employed to polymerize dienes and are then combined with controlled saturation methods, a wide panoply of saturated hydrocarbon polymers can be made. These products can serve as models for commercial polyolefins, which is the most widely used class of synthetic polymers and which continues to develop at a strong pace. The ability to make such models with highly controlled chain architectures, plus the ability to label the molecules for use in techniques such as NMR and neutron scattering, has provided polymer physicists with means to understand polyolefin physics at a deep level. This has been used to determine the size of polyolefin chains (both in dilute solution and in melt state), the ways that polyolefins mix, how their rheology depends on the chemical structure of the chains, and how long branches control their performance. This chapter covers not only the scientific results of this research, but also how these can be applied in the development of novel, useful polyolefin products.

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Well-Defined Comb, Star−Comb, and Comb-on-Comb Polybutadienes by Anionic Polymerization and the Macromonomer Strategy

Cited by 91 publications

References 24 publications

Anionic Synthesis and Rheological Characterization of Poly(p‐methylstyrene) Model Comb Architectures with a Defined and Very Low Degree of Long Chain Branching

Anionic Synthesis and Rheological Characterization of Poly(p‐methylstyrene) Model Comb Architectures with a Defined and Very Low Degree of Long Chain Branching

HyperMacs – long chain hyperbranched polymers: A dramatically improved synthesis and qualitative rheological analysis

The Critical Role of Anionic Polymerization for Advances in the Physics of Polyolefins

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