Quasi-Elastic Light Scattering Study of Concentration Dependence of Diffusion and Internal Motion in Chain Polymers

Nishio, Izumi; Wada, Akira

doi:10.1295/polymj.12.145

Cited by 22 publications

(9 citation statements)

References 13 publications

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“…In the past decades, numerous efforts have been devoted to the understanding of internal dynamics for linear chains. − In related studies, the main focuses are the scaling behavior of the first cumulant [Γ( q )], the asymptotic behavior of the reduced first cumulant (Γ* = [η 0 Γ( q )/( k B Tq 3 )]), and the characteristic relaxation time (τ 1 ) of the first internal mode, where η 0 is the solvent viscosity, and a qualitatively satisfying agreement has been achieved between experimental findings and theoretical predictions. − …”

Section: Introductionmentioning

confidence: 92%

Light Scattering Study of Internal Motions of Ultralong Comb-like Chains in Dilute Solutions under Good Solvent Conditions

et al. 2020

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Internal dynamics of polymer chains is one of the most important fundamental problems in polymer physics. This work reports the first example of a dynamic light scattering (DLS) study of internal motions of well-defined ultralong comb-like chains in dilute solutions under good solvent conditions. Using two well-characterized comb-like model samples with controlled parameters and narrow distributions (M w /M n ≈ 1.30 and M w ≈ 10 7 g/mol), the asymptotic behavior of the reduced first cumulant [Γ* = Γ(q)/(q 3 k B T/ η 0 )], the number of relaxation modes in Γ(q) distribution curves, the characteristic relaxation time (τ 1 ) of the first internal mode, and the q-dependent relative strength of internal motions have been experimentally quantified and carefully analyzed where q is the scattering vector. Specifically, the DLS results reveal the following: (i) Γ*(q ≫ 1), that is, the value of Γ* at the very high q regime, is not sensitive to structural details (local rigidity and side chain length); (ii) similar to hyperbranched polymers, the asymptotic power law in the regime of 3.0 < (q⟨R g ⟩) < 5.5 is also found to be a better indicator, which could reflect the structural details for comb-like polymers; (iii) the comparison of experimentally determined and theoretically calculated values of τ 1 shows that the classical theory of linear chains could still satisfactorily describe the intrachain relaxation behavior of comb-like chains; and (iv) the side-chain grafting-induced rigidity could result in an enhanced separation of translational and internal motions but simultaneously result in a significant suppression of the strength of overall internal motions. The present study not only reveals that the modes of internal motions of a given system are mainly determined by the relaxation of the main contour of a given chain structure rather than the local chain rigidity but also provides useful experimental data for further theoretical modeling of internal dynamics of various topological polymers.

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Section: Introductionmentioning

confidence: 92%

Light Scattering Study of Internal Motions of Ultralong Comb-like Chains in Dilute Solutions under Good Solvent Conditions

et al. 2020

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“…In the past four decades, numerous experimental efforts have been devoted to the understanding of internal dynamics for linear polymers, − to name a few, but limited attention was paid to branched systems. − Nowadays, it is well known that the internal dynamics of linear chains in dilute solution are governed by strong hydrodynamic interactions, and a qualitatively satisfying agreement between experimental findings and theoretical predictions has been obtained. − In related studies, the main focus is on the scaling behavior of the first cumulant [Γ( q )], the asymptotic behavior of the reduced first cumulant [Γ*, Γ* = Γ( q )/( q 3 k B T /η 0 )], and the characteristic relaxation time (τ 1 ) of the first internal mode, where η 0 is the solvent viscosity. For branched polymers like randomly hyperbranched polymers, it is still an open question how branching does influence the internal segmental motion and the hydrodynamic interaction, although much attention has already been paid to their static properties. − For the purpose of internal motion study, the main difficulty lies in the lack of suitable model hyperbranched samples with controlled branching patterns.…”

Section: Introductionmentioning

confidence: 99%

Light Scattering Study of Internal Dynamics of Hyperbranched Polymers with Controlled Branching Patterns and Low Polydispersities in Dilute Solutions

Hao

Zhu

2019

Macromolecules

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Internal dynamics of flexible polymer chains is one of the most important fundamental problems in polymer physics. Although numerous efforts have been devoted to the understanding of internal dynamics for linear polymers, little attention was paid to branched systems. This work aims to elucidate how the branching effect quantitatively influences the internal motions of long-subchain hyperbranched polymers in dilute solution. By light scattering study of four hyperbranched polystyrene samples with controlled branching patterns and low polydispersities (M w/M n < 1.40 and M w ∼ 107 g/mol), we quantified and analyzed the asymptotic behavior of the reduced first cumulant [Γ* = Γ(q)/(q 3 k B T/η0)], the value of Γ* at high q-regime [the approximate values of Γ*(∞)], the scattering vector (q) dependence of linewidth [Γ(q)], the number of relaxation modes in Γ(q)-distribution curves, the characteristic relaxation time (τ1) of the first internal mode, and the q-dependent relative strength of internal motions. Our results reveal: (i) Γ*(∞) is not sensitive to the branching density, but more related to the fractal dimension of a given system; (ii) the asymptotic power law in the intermediate qR h regime (1.5 < qR h < 3.0), compared to Γ*(∞), is a better indicator, which could reflect the structural details of different branched systems; (iii) the branching effect could lead to the suppression of overall internal motions, but the introduction of moderate branching could enhance the contribution of some energetically favorable internal modes in linewidth distribution; (iv) by comparing the experimentally determined and theoretically calculated τ1, the result provides direct experimental evidence supporting that the classical theory is not applicable to hyperbranched polymer systems. The present work not only helps clarify some long-standing controversial issues existed in previous studies, but also provides useful experimental data for further theoretical calculations of internal dynamics for branched systems.

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“…t (min) Figure 11. Relation between reaction time and sequence structure of PMMA initiated by rc-BuLi at -21 °C.…”

mentioning

confidence: 99%

The internal modes of polystyrene single coils studied using dynamic light scattering

Nicolai¹,

Brown²,

Johnsen³

1989

Macromolecules

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Quasi-Elastic Light Scattering Study of Concentration Dependence of Diffusion and Internal Motion in Chain Polymers

Cited by 22 publications

References 13 publications

Light Scattering Study of Internal Motions of Ultralong Comb-like Chains in Dilute Solutions under Good Solvent Conditions

Light Scattering Study of Internal Motions of Ultralong Comb-like Chains in Dilute Solutions under Good Solvent Conditions

Light Scattering Study of Internal Dynamics of Hyperbranched Polymers with Controlled Branching Patterns and Low Polydispersities in Dilute Solutions

The internal modes of polystyrene single coils studied using dynamic light scattering

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