Detecting Structural Polydispersity in Branched Polybutadienes

Li, Si Wan; Park, Heon E.; Dealy, John M.; Marić, Milan; Lee, Hyojoon; Im, Kyuhyun; Choi, Heungyeal; Chang, Taihyun; Rahman, M. Shahinur; Mays, Jimmy W.

doi:10.1021/ma101803h

Cited by 40 publications

(44 citation statements)

References 23 publications

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“…The efficiency of the two coupling methods are compared and the 'purified' star polymers characterised by both SEC and Temperature Gradient Interaction Chromatography (TGIC). Whilst SEC has been the characterisation method of choice for many decades, for the analysis of molecular weight and molecular weight distribution of polymers, in recent years TGIC has emerged as a technique capable of significantly enhanced resolution compared to SEC, especially in the characterisation of branched polymers [12,14,[68][69][70][71]] -a subject recently reviewed in detail [72]. In the current work TGIC revealed low levels of heterogeneity in the purified (fractionated) stars -heterogeneity which could not be detected by SEC.…”

Section: Introductionmentioning

confidence: 67%

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

Agostini¹

2013

European Polymer Journal

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. (2013) 'Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the "macromonomer"approach.', European polymer journal., 49 (9). pp. 2769-2784. Further information on publisher's website:http://dx.doi.org/10.1016/j.eurpolymj.2013.06.021Publisher'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, 49, 9, 2013Journal, 49, 9, , 10.1016Journal, 49, 9, /j.eurpolymj.2013.021. 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 describe herein the synthesis and characterisation of a series of asymmetric three arm polystyrene stars via the "macromonomer" approach. The stars have been designed as model polymers to probe branched polymer dynamics and in particular to establish the chain-length of side-arm which precipitates a change in the rheological properties of the resulting polymers from "linear-like" to "star-like". Thus, a homologous series of three arm stars have been prepared in which the molar mass of two (long) arms are fixed at 90 000 gmol -1 and the molar mass of the remaining (short) arm is varied from below the entanglement molecular weight (M e ) to above M e . The arms were prepared by living anionic polymerisation, resulting in well-defined chain lengths with narrow molecular weight distribution. In contrast to the usual chlorosilane coupling approach, the macromonomer approach involves the introduction of reactive chain-end functionalities on each of the arms, either through the use of a functionalised (protected) initiator or a functional end-capping agent, which allows the stars to be constructed by a simple condensation coupling reaction. In this study we will compare the relative efficiency of a Williamson and 'click' coupling reaction in producing the stars. Most significantly, although this approach maybe a little more time-consuming than the more common silane coupling reaction, in the present study the "long" arm may be produced in sufficient quantity such that all of the asymmetric stars are produced with long arms of identical molecular weight -the only remaining variable being the molecular weight of th...

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Section: Introductionmentioning

confidence: 67%

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

Agostini¹

2013

European Polymer Journal

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“…The primary impediments are that (i) synthesizing well-defined and well-characterized BPs is highly nontrivial [7,[215][216][217][218][219][220][221], (ii) the process of testing and calibrating the rheological models exposes many weaknesses of the tube model that are not manifested for LPs [158,159], and (iii) there is no counterpart to the "double reptation" model because of the complexity of the computational models. Even so, the past few years have seen tremendous progress.…”

Section: Methods and Progressmentioning

confidence: 99%

“…They found rheology to be more sensitive to branching, as expected, but reported that a combination of both the methods resulted in better overall characterization. Some of the works previously referenced also employ multidetector methods [88,219,220,302,315].…”

Section: Experimental Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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The extreme sensitivity of rheology to the microstructure of polymer melts has prompted the development of "analytical rheology," which seeks inferring the structure and composition of an unknown sample based on rheological measurements. Typically, this involves the inversion of a model, which may be mathematical, computational, or completely empirical. Despite the imperfect state of existing models, analytical rheology remains a practically useful enterprise. I review its successes and failures in inferring the molecular weight distribution of linear polymers and the branching content in branched polymers.

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“…The use of model polymers of well-defined architecture is important in probing molecular rheology [1][2][3][4]. Indeed, substantial progress has been made in decoding the linear viscoelasticity of model branched polymers (such as combs or pom-pom-like macromolecules), and more recently their nonlinear response in shear and extension.…”

Section: Introductionmentioning

confidence: 99%

Stress growth and relaxation of dendritically branched macromolecules in shear and uniaxial extension

Huang¹,

Costanzo²,

Das³

et al. 2017

Journal of Rheology

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We present unique nonlinear rheological data of well-defined symmetric Cayley-tree poly(methyl methacrylates) in shear and uniaxial extension. Earlier work has shown that their linear viscoelasticity is governed by the hierarchical relaxation of different generations, whereas the segments between branch points are responsible for their substantial strain hardening as compared to linear homopolymers of the same total molar mass at the same value of imposed stretch rate. Here, we extend that work in order to obtain further experimental evidence that will help understanding the molecular origin of the remarkable properties of these highly branched macromolecules. In particular, we address three questions pertinent to the specific molecular structure: (i) is steady state attainable during uniaxial extension? (ii) what is the respective transient response in simple shear? and (iii) how does stress relax upon cessation of extension or shear? To accomplish our goal we utilize state-of-the-art instrumentation, i.e., filament stretching rheometry (FSR) and cone-partitioned plate (CPP) shear rheometry for polymers with 3 and 4 generations, and complement it with state-of-the-art modeling predictions using the Branch-on-Branch (BoB) algorithm. The data indicates that the extensional viscosity reaches a steady state value, whose dependence on extension rate is identical to that of entangled linear and other branched polymer melts. Nonlinear shear is characterized by transient stress overshoots and the validity of the Cox-Merz rule. Remarkably, nonlinear stress relaxation is much broader and slower in extension compared to shear. It is also slower at higher generation, and rate-independent for rates below the Rouse rate of the outer segment. For extension, the relaxation time is longer than that of the linear stress relaxation, suggesting a strong 'elastic memory' of the material. These results are 2 described by BoB semi-quantitatively, both in linear and nonlinear shear and extensional regimes. Given the fact that the segments between branch points are less than 3 entanglements long, this is a very promising outcome that gives confidence in using BoB for understanding the key features. Moreover, the response of the segments between generations controls the rheology of the Cayley trees. Their substantial stretching in uniaxial extension appears responsible for strain hardening, whereas coupling of stretches of different parts of the polymer appears to be the origin of the slower subsequent relaxation of extensional stress. Concerning the latter effect, for which predictions are not available, it is hoped that the present experimental findings and proposed framework of analysis will motivate further developments in the direction of molecular constitutive models for branched and hyperbranched polymers.

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Detecting Structural Polydispersity in Branched Polybutadienes

Cited by 40 publications

References 23 publications

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

Analytical Rheology of Polymer Melts: State of the Art

Stress growth and relaxation of dendritically branched macromolecules in shear and uniaxial extension

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