Molecular Insight into the Effects of Clustering on the Dynamics of Ionomers in Solutions

Mohottalalage, Supun; Kosgallana, Chathurika; Senanayake, Manjula; Wijesinghe, Sidath; Osti, Naresh C.; Perahia, Dvora

doi:10.1021/acsmacrolett.3c00353

Cited by 4 publications

(4 citation statements)

References 44 publications

(94 reference statements)

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“…Here, we assume a two-level model, where in the low q regime a network of relatively large highly swollen domains is formed. Within these domains, the chains are confined by ionic clusters, with a high fraction of the polymer solvated in toluene, assuming close to a Gaussian configuration. Based on the MD simulations, the q range in which the interionic cluster correlation is manifested and the broad distribution of cluster size and shape smear the signature in the pattern.…”

Section: Methodsmentioning

confidence: 99%

“…The structure and mechanical response of SPS have been extensively studied, ,,,,− pointing to direct correlation between clustering and rheology of the melts. Pioneering insight attained by Weiss and coworkers demonstrate a correlation between the clustering, structure, and rheological characteristics of SPS melts. ,− They have shown that the cluster formation of short oligomers of approximately 4 kg/mol constrains the polymer motion, resulting in rheological response akin to those of long entangled polymers .…”

Section: Introductionmentioning

confidence: 99%

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Clustering Effects on the Structure of Ionomer Solutions: A Combined SANS and Simulations Study

Kosgallana,

Senanayake,

Mohottalalage

et al. 2024

Macromolecules

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Ionic assemblies, or clusters, determine the structure and dynamics of ionizable polymers and enable their many applications. Fundamental to attaining well-defined materials is controlling the balance between the van der Waals interactions that govern the backbone behavior and the forces that drive the formation of ionic clusters. Here, using small-angle neutron scattering and fully atomistic molecular dynamics simulations, the structure of a model ionomer, sulfonated polystyrene in toluene solutions, was investigated as the cluster cohesion was tweaked by the addition of ethanol. The static structure factor was measured by both techniques and correlated with the size of the ionic clusters as the polymer concentration was varied. The conjunction of SANS results and molecular insight from MD simulations enabled the determination of the structure of these inhomogeneous networks on multiple length scales. We find that across the entire concentration range studied, a network driven by the formation of ionic clusters was formed, where the size of the clusters drives the inhomogeneity of these systems. Tweaking the ionic clusters through the addition of ethanol impacts the packing of the sulfonated groups, their shape, and their size distribution, which, in turn, affects the structure of these networks.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Clustering Effects on the Structure of Ionomer Solutions: A Combined SANS and Simulations Study

Kosgallana,

Senanayake,

Mohottalalage

et al. 2024

Macromolecules

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“…This motion increases with increasing temperature with a distinctive transition to a faster dynamics at the θ temperature of the polystyrene backbone in cyclohexane. 33 With results from real and reciprocal space, the current study strives to correlate the effects of clustering on the translation of constraint dynamics from the atomistic level and segmental length scales to the overall motion of the polymers, using suflonated polystyrene in the ionomer regime. SPS in its ionomer regime, where well-defined clusters are formed, is a well-studied polymer whose synthetic routes lead to narrow molecular weight distribution and the degree of sulfonation can be controlled.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Our recent quasi elastic neutron scattering (QENS) studies have shown that the dynamics of SPS in its acid form, in cyclohexane, a poor solvent for both the backbone and the sulfonated groups at room temperature, is constrained on the length scale of the rigid segment of the polymer, the length scale accessible to QENS. This motion increases with increasing temperature with a distinctive transition to a faster dynamics at the θ temperature of the polystyrene backbone in cyclohexane …”

Section: Introductionmentioning

confidence: 99%

From Molecular Constraints to Macroscopic Dynamics in Associative Networks Formed by Ionizable Polymers: A Neutron Spin Echo and Molecular Dynamics Simulations Study

Kosgallana,

Wijesinghe,

Senanayake

et al. 2024

ACS Polym. Au

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The association of ionizable polymers strongly affects their motion in solutions, where the constraints arising from clustering of the ionizable groups alter the macroscopic dynamics. The interrelation between the motion on multiple length and time scales is fundamental to a broad range of complex fluids including physical networks, gels, and polymer−nanoparticle complexes where long-lived associations control their structure and dynamics. Using neutron spin echo and fully atomistic, multimillion atom molecular dynamics (MD) simulations carried out to times comparable to that of chain segmental motion, the current study resolves the dynamics of networks formed by suflonated polystryene solutions for sulfonation fractions 0 ≤ f ≤ 0.09 across time and length scales. The experimental dynamic structure factors were measured and compared with computational ones, calculated from MD simulations, and analyzed in terms of a sum of two exponential functions, providing two distinctive time scales. These time constants capture confined motion of the network and fast dynamics of the highly solvated segments. A unique relationship between the polymer dynamics and the size and distribution of the ionic clusters was established and correlated with the number of polymer chains that participate in each cluster. The correlation of dynamics in associative complex fluids across time and length scales, enabled by combining the understanding attained from reciprocal space through neutron spin echo and real space, through large scale MD studies, addresses a fundamental long-standing challenge that underline the behavior of soft materials and affect their potential uses.

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Backscattering silicon spectrometer (BASIS): sixteen years in advanced materials characterization

Osti,

Jalarvo,

Mamontov

2024

Mater. Horiz.

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Molecular Insight into the Effects of Clustering on the Dynamics of Ionomers in Solutions

Cited by 4 publications

References 44 publications

Clustering Effects on the Structure of Ionomer Solutions: A Combined SANS and Simulations Study

Clustering Effects on the Structure of Ionomer Solutions: A Combined SANS and Simulations Study

From Molecular Constraints to Macroscopic Dynamics in Associative Networks Formed by Ionizable Polymers: A Neutron Spin Echo and Molecular Dynamics Simulations Study

Backscattering silicon spectrometer (BASIS): sixteen years in advanced materials characterization

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