Star Polymers: Experiment, Theory, and Simulation

Grest, Gary S.; Fetters, Lewis J.; Huang, John S.; Richter, D.

doi:10.1002/9780470141533.ch2

Cited by 250 publications

(280 citation statements)

References 203 publications

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“…The theoretical [22,23] and experimental [24][25][26][27][28][29] studies of branched polymers provide us with a reason to assume that these macromolecules are more efficient in comparison with linear analogs for the nanosystem in situ synthesis, as flocculants and nanocarriers for drugs, because of a higher local concentration of functional groups capable of reacting with some substances. It was proved by our recent research devoted to the encapsulation of cis-Pt into a branched star-like polymer with dextran core and grafted polyacrylamide-co-polyacrylic acid arms.…”

Section: Introductionmentioning

confidence: 99%

Aggregation Processes in Hybrid Nanosystem Polymer/Nanosilver/Cisplatin

Kutsevol¹,

Naumenko²,

Chumachenko³

et al. 2018

Ukr. J. Phys.

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AGGREGATION PROCESSES IN HYBRID NANOSYSTEM POLYMER/NANOSILVER/CISPLATINHybrid nanosystems consisting of star-like copolymer Dextran-graft-Polyacrylamide in the anionic form (D-g-PAA(PE)), silver nanoparticles (AgNPs), and cisplatin (cis-Pt) have been synthesized in water and characterized by TEM, DLS, FTIR, and UV-Vis spectroscopies. It is shown that cis-Pt forms a complex with carboxylate groups of the polymer. For the ternary system Polymer/AgNPs/cis-Pt, a change in the hydrophilic-hydrophobic balance of a polymer molecule (due to the complexation with cis-Pt) and the aggregation of macromolecules, as well as to some agglomeration AgNPs, are revealed. The decrease of the antitumor efficiency of the hybrid ternary nanosystem Polymer/AgNPs/cis-Pt in comparison with the Polymer/cis-Pt system is discussed.K e y w o r d s: silver nanoparticles, branched polymer, polyelectrolyte, cisplatin, aggregation.

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Section: Introductionmentioning

confidence: 99%

Aggregation Processes in Hybrid Nanosystem Polymer/Nanosilver/Cisplatin

Kutsevol¹,

Naumenko²,

Chumachenko³

et al. 2018

Ukr. J. Phys.

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“…However, in the overwhelming majority of cases, industrially produced materials have a wide distribution of chain lengths between branch points, making modelling of the material challenging. It is this realisation that has, over a period of decades, resulted in the design and synthesis of well-defined molecular architectures such as star branched polymers [2,3], mikto star polymers [4][5][6] and H-shaped polymers [7,8] with a view to understanding and predicting the relationship between structure and properties. More recently, syntheses of dendrigraft, dendritically branched and arborescent [9][10][11][12][13][14] polymers with a higher degree and complexity of branching have been published, much of this work has recently been reviewed by Gauthier and Teertstra [15].…”

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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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“…The dependence of the size of a star polymer on the number of its arms f star is expressed as f ð1À Þ=2 star . 5,29) The diffusion constant of the subunits to relax is proportional to the inverse of their numbers, because no hydrodynamic interaction is present. Since the diffusion time is given by the square of the size divided by the diffusion constant, we obtaiñ…”

Section: Relaxation Processes Of Dendrimersmentioning

confidence: 99%

“…[1][2][3][4][5][6] As new polymeric materials with complex architectures are synthesized, it becomes more important to reveal the relation between the architecture of polymers and their dynamic behavior. In particular, much recent interest has been focused on branched polymers.…”

Section: Introductionmentioning

confidence: 99%

Relaxation of a Single Dendrimer

Iwaoka

Takano

2013

J. Phys. Soc. Jpn.

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Relaxation process of a single dendrimer with excluded volume effects is studied in the free-draining limit for various parameters characterizing the architecture of the dendrimer, which are the functionality of central segment f c , the functionality of branching segments f , the number of generations G and the number of bonds in each spacer between branching segments P. By assuming that the dendrimer relaxes hierarchically from the outermost generation to the central segment after relaxation of the spacers, a scaling law 1 $ f 1À c fð f À 1Þf 1À g GÀ1 P 2 þ1 for the longest relaxation time 1 is derived, where % 0:588 is the Flory exponent. Another scaling law for relaxation times of other antisymmetric relaxation modes is also derived. In order to verify the scaling laws, Brownian dynamics simulations of a single dendrimer are performed and relaxation times are estimated by the relaxation mode analysis method. The scaled relaxation time 1 =ð f 1À c P 2 þ1 Þ is proportional to fð f À 1Þf 1Àx g GÀ1 , where the exponent x corresponding to is estimated as x % 0:66 for f ¼ 3 and 0.63 for f ¼ 4. It is found that 1 =ð f 1À c fð f À 1Þf 1Àx g GÀ1 Þ / P 2yþ1 , where the exponent y that corresponds to is estimated as y % 0:58. The agreement with the predicted scaling law becomes better as G and f becomes larger, where the concentration of segments becomes larger. The other scaling law for other antisymmetric relaxation modes is also verified.

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Star Polymers: Experiment, Theory, and Simulation

Cited by 250 publications

References 203 publications

Aggregation Processes in Hybrid Nanosystem Polymer/Nanosilver/Cisplatin

Aggregation Processes in Hybrid Nanosystem Polymer/Nanosilver/Cisplatin

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

Relaxation of a Single Dendrimer

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