Model linear and star-shaped polyisoprenes with phosphatidylcholine analogous end-groups. Synthesis and association behavior in cyclohexane

Charalabidis, D.; Pitsikalis, Marinos; Hadjichristidis, Nikos

doi:10.1002/1521-3935(200210)203:14<2132::aid-macp2132>3.0.co;2-x

Cited by 12 publications

(19 citation statements)

References 33 publications

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“…35,[43][44][45][46] Among them, model macromolecules with polar end groups represent a simple system to study the mechanism driving intra-and intermolecular aggregation and related properties. 2,24,[40][41][42][47][48][49][50][51][52][53][54] Such polymers of different architectures were obtained from anionic synthesis. 35,40,[52][53][54] In previous work, we have shown that selective functionalization of linear and three-arm star polymers (of varying molecular weights) with strong dipolar end groups yields a variety of selforganized structures and a respective dynamics much different from that of the nonfunctionalized precursor polymers, thus providing a means for supramolecular structural control.…”

Section: Introductionmentioning

confidence: 99%

“…2,24,[40][41][42][47][48][49][50][51][52][53][54] Such polymers of different architectures were obtained from anionic synthesis. 35,40,[52][53][54] In previous work, we have shown that selective functionalization of linear and three-arm star polymers (of varying molecular weights) with strong dipolar end groups yields a variety of selforganized structures and a respective dynamics much different from that of the nonfunctionalized precursor polymers, thus providing a means for supramolecular structural control. 47,48,55 Despite the progress in understanding supramolecular systems, the melt dynamics of highly entangled telechelic stars of varying functionalities and molecular weights has not been addressed.…”

Section: Introductionmentioning

confidence: 99%

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Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts

et al. 2010

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We investigate the linear viscoelastic response of model telechelic linear and star (of varying functionality) polyisoprene melts with different molar masses above the entanglement limit in relation to their structure. We find that these systems self-assemble as a result of the strong dipolar interactions and form clusters that seem to depend primarily on the number of dipolar groups per star. The dynamics is rather complex, but some pertinent features are observed: the segmental dynamics is affected by the telechelic functionalization, especially for short arm lengths; this reflects the change of microstructure (and thus glass-transition temperature) with functionalization. The terminal relaxation is much slower compared to similar nonionic stars, reflecting the relaxation of clusters. Linear semitelechelic polymers (with only one end functionalized) aggregate in a star-like fashion. We further develop a tube model based on the time-marching algorithm for stars and linear chains, where we incorporate the association status of the chains via the dipolar interactions at each time step. The agreement of the predictions with the data, using two adjustable parameters (the average times when two dipolar pair remain associated or free, respectively), is remarkable and suggests design criteria for forming desired supramolecular assemblies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts

et al. 2010

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“…In this work, we present a strategy for developing and investigating well-defined star-shaped block copolymer systems in solvents of varying quality that act as building blocks for supramolecular assemblies using a combination of syntheses, simulations and physical experiments. Given the broad scope and advances in the field of associating polymers, , we focus on telechelic star polymers (TSPs), which carry associating monomers at their ends. − A TSP comprises f AB-block copolymers (arms) grafted on a common center with their solvophilic A-blocks being at the interior of the star and their solvophobic B-blocks attached to the end of each arm. In what follows, N A and N B denote the number of A- and B-type monomers in a star arm, respectively, and α = N B /( N A + N B ) is the relative size ratio between the two block lengths.…”

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Self-Organization and Flow of Low-Functionality Telechelic Star Polymers with Varying Attraction

et al. 2019

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We combine state-of-the art synthesis, simulations, and physical experiments to explore the tunable, responsive character of telechelic star polymers as models for soft patchy particles. We focus on the simplest possible system: a star comprising three asymmetric block copolymer arms with solvophilic inner and solvophobic outer blocks. Our dilute solution studies reveal the onset of a second slow mode in the intermediate scattering functions as the temperature decreases below the θ-point of the outer block, as well as the size reduction of single stars upon further decreasing temperature. Clusters comprising multiple stars are formed and their average dimensions, akin to the single star size, counterintuitively decrease upon cooling. A similar phenomenology is observed in simulations upon increasing attraction between the outer blocks and is rationalized as a result of the interplay between interstar associations and steric repulsion between the star cores. Since our simulations are able to describe the experimental findings reliably, we can use them with confidence to make predictions at conditions and flow regimes that are inaccessible experimentally. Specifically, we employ simulations to investigate flow properties of the system at high shear rates, revealing shear thinning behavior caused by the breakup of interstar associations under flow. On the other hand, the zero-shear viscosity obtained experimentally exhibits a rather weak activation energy, which increases upon rising star concentration. These findings demonstrate the unusual properties of telechelic star polymers even in the dilute regime. They also offer a powerful toolbox for designing soft patchy particles and exploring their unprecedented responsive properties further on.

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“…Over the past several years special attention has been given in the synthesis of polymers bearing dimethylamino functional endgroups and their transformation to zwitterions [43]. Linear homopolymers [44,45] and block copolymers [46][47][48] along with star polymers bearing different numbers of polar groups [49][50][51][52][53][54] have been previously prepared and their association behavior has been studied both in non-polar solvents and in bulk. The nature and the number of end-groups, the nature and the molecular weight of the macromolecular chain, along with the architecture are the key factors influencing the behavior in solution and in bulk.…”

Section: Introductionmentioning

confidence: 99%

Complexes of end-functionalized polystyrenes carrying amine end-group with transition metals: association effects in organic solvents

2019

Biointerface Res Appl Chem

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Linear end-functionalized polystyrenes of different molecular weights bearing amino end-group (NPS) were synthesized by anionic polymerization high vacuum techniques. The polymers were exposed to copper and iron salts (CuCl2.2H2O and FeCl3.6H2O) to form complexes with specific metal/amino molar ratios. The thermal stability of these complexes was studied by Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), whereas their solution behavior was studied by Low Angle Laser Light Scattering (LALLS), Dynamic Light Scattering (DLS) and dilute solution Viscometry. Extended aggregation phenomena of these complexes were observed in organic solvents. The association behavior was influenced by the molecular weight of the polymer chain, the metal/amine group molar ratio, the chemical nature of the metal and the polarity of the solvent. A complex situation was revealed by DLS showing the existence of equilibrium between aggregates and clusters. Under the influence of shear forces applied in the capillary tube of the viscometer the clusters are disrupted.

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Model linear and star-shaped polyisoprenes with phosphatidylcholine analogous end-groups. Synthesis and association behavior in cyclohexane

Cited by 12 publications

References 33 publications

Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts

Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts

Self-Organization and Flow of Low-Functionality Telechelic Star Polymers with Varying Attraction

Complexes of end-functionalized polystyrenes carrying amine end-group with transition metals: association effects in organic solvents

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