Monte Carlo study of ring polymers

Naghizadeh, J.; Sotobayashi, Hideto

doi:10.1063/1.1681496

Cited by 30 publications

(11 citation statements)

References 22 publications

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“…(1/12 )(12 + 22 + 22 2 + 12 3)}} (16) In Figure 4, we show a plot of ß vs ß. The aspect of this function is similar to that of gs vs ß, with a maximum at ß = 0.5, indicating the greatest segregation between blocks symmetric in composition.…”

Section: Perturbation Calculationsmentioning

confidence: 99%

Conformational Properties of Ring AB Diblock Copolymers

Vlahos¹,

Hadjichristidis²,

Kosmas³

et al. 1995

Macromolecules

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Section: Perturbation Calculationsmentioning

confidence: 99%

Conformational Properties of Ring AB Diblock Copolymers

Vlahos¹,

Hadjichristidis²,

Kosmas³

et al. 1995

Macromolecules

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“…While all experimental studies have dealt with the dilute solution behavior of cyclic molecules [1][2][3][4] theoretical and computational work has been carried out on cyclics, in bulk. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] The general conclusion is that the conformation of rings in the melt differs significantly from that in solution, as a result of topological constraints active in concentrated systems but not in dilute solution.…”

Section: Introductionmentioning

confidence: 99%

On the difference in scattering behavior of cyclic and linear polymers in bulk

Gagliardi

Arrighi

Ferguson

et al. 2005

The Journal of Chemical Physics

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It has been suggested that, due to topological constraints, rings in the melt may assume a more compact shape than Gaussian chains. In this paper, we exploit the availability of narrow fractions of perdeuterated linear and cyclic polydimethylsiloxane ͑PDMS͒ and, through the analysis of the small angle neutron scattering ͑SANS͒ profiles, demonstrate the difference in scattering properties of linear and cyclic PDMS molecules. As expected for Gaussian chains, for the H/D linear PDMS samples, log-log plots of the scattered intensity versus scattering vector Q display a Q ͑−2͒ dependence. However, for H/D cyclic blends, the scaling exponent is higher than 2, as predicted by computer simulations reported in the literature. We show that cyclic molecules in bulk display the characteristic maximum in plots of scattered intensity versus Q ͑−2͒ that is expected on the basis of Monte Carlo calculations and from the Casassa equation ͓E. F. Casassa, J. Polym. Sci. A 3, 605 ͑1965͔͒. It is also shown that, for rings, the Debye equation ͓P. Debye, J. Appl. Phys. 15, 338 ͑1944͔͒ is no longer appropriate to describe the SANS profiles of H/D cyclic blends, at least up to M w Ϸ 10 000. For these samples, the Casassa form factor gives a better representation of the SANS data and we show that this function which was developed for monodisperse cyclics is still adequate to describe our slightly polydisperse samples. Deviations from all above observations are noted for M w Ͼ 11 000 and are attributed to partial contamination of cyclic samples with linear chains. The failure of both the Debye and the Casassa form factors could be due to contamination of the cyclic fractions by linear polymers or to a real conformational change.

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“…Various physical properties of cyclic polymers have been predicted not only by theoretical methods [1][2][3][4] but also by computer simulation studies, [5][6][7] while they have also been examined experimentally. [8][9][10][11][12][13][14] Cyclic polymers were usually synthesized by the coupling reaction between living precursor polymers with functional groups on both ends and bifunctional linking agents.…”

mentioning

confidence: 99%

Preparation and Characterization of Cyclic Polystyrenes

Cho

Masuoka

Koguchi

et al. 2005

Polym J

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ABSTRACT:Macrocyclic polystyrenes with various molecular weight were prepared by the reaction of linear polystyrene having two end vinyl groups and potassium naphthalenide as a coupling agent. Intermolecular side reactions produced higher molecular weight polycondensates and undesirable chain termination reactions also produced linear precursors in addition to the designed molecules. In order to isolate cyclic polymers from the ring closure reaction mixtures, preparative size exclusion chromatography (SEC) method was employed. The purity of SEC-fractionated cyclic polystyrenes was rigorously examined by liquid chromatography at the critical condition (LCCC) and interaction chromatography (IC). After SEC-fractionation, we obtained large amount of highly pure cyclic polymers, though high molecular weight cyclic polymers contain very small amount of linear precursor (< 5%). The purity and isotope effect on reversed-phase liquid chromatography (RPLC) were also rigorously investigated by preparing a deuterated cyclic polystyrene. [DOI 10.1295/polymj.37.506] KEY WORDS Cyclic Polystyrene / GPC Fractionation / LCCC / Isotope Effect / Cyclic macromolecules are of great interest in the investigation of the influence of cyclization on their solution, melt, and solid-state properties. Various physical properties of cyclic polymers have been predicted not only by theoretical methods 1-4 but also by computer simulation studies, 5-7 while they have also been examined experimentally. [8][9][10][11][12][13][14] Cyclic polymers were usually synthesized by the coupling reaction between living precursor polymers with functional groups on both ends and bifunctional linking agents. For example, polystyrenes 9,15-19 and poly(2-vinylpyridine)s 20,21 have been synthesized by this method. Furthermore, , !-heterobifunctional polymers have been used for the synthesis of cyclic polymers.22-24 However, side reactions produce linear precursor polymers, and intermolecular reactions simultaneously produce dimeric and higher molecular weight linear polycondensates. Therefore, it is very difficult to obtain pure cyclic polymers directly, and fractionation is necessary in order to obtain cyclic polymers with high purity. For the isolation of cyclic polymers from the ring closure reaction mixtures, two major fractionation methods have been employed: fractional precipitation method 9,14,[16][17][18] and preparative size exclusion chromatography (SEC). 25,26 Furthermore, liquid chromatography at the critical condition method (LCCC) has been successfully applied for the characterization of cyclic polymers.27-30 Throughout these experimental studies, however, the direct evidence of cyclic structure was not shown, in addition to the fact that the purity of the cyclic molecules has not been determined quantitatively in most of the works. Only for the low molecular weight cyclic polymers, the detailed cyclic structures were directly confirmed by NMR analysis of linking points, 22,23 pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 31 and matri...

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Monte Carlo study of ring polymers

Cited by 30 publications

References 22 publications

Conformational Properties of Ring AB Diblock Copolymers

Conformational Properties of Ring AB Diblock Copolymers

On the difference in scattering behavior of cyclic and linear polymers in bulk

Preparation and Characterization of Cyclic Polystyrenes

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