New Insights into Ionic Aggregate Morphology in Zn-Neutralized Sulfonated Polystyrene Ionomers by Transmission Electron Tomography

Dalmas, Florent; Leroy, Éric

doi:10.1021/ma201707j

Cited by 15 publications

(8 citation statements)

References 34 publications

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“…Extensive investigations were focused on the structure characterization of ionic aggregates and the ionomer morphology by using X-ray scattering, ,, transmission electron microscopy (TEM), − and dynamic mechanical analysis (DMA). ,, However, the basic knowledge about the network structure and chain dynamics is still insufficient in order to understand the exceptional elastic properties of these complex materials.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR

et al. 2014

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The network structure and chain dynamics of ionic elastomers based on carboxylated nitrile rubber (XNBR) cross-linked with different content of magnesium oxide (MgO) have been studied by different low-field time-domain NMR experiments. Ionic contacts created during the vulcanization tend to aggregate trapping some polymer segments that show restricted mobility as it was quantified by analyses of refocused free induction decays. Increasing the MgO content above the stoichiometric fraction has no effect on the amount of trapped polymer segments, but it increases the network cross-link density as measured by multiple-quantum (MQ) NMR experiments. The central finding of this work is that MgO addition above the stoichiometric content enhances the mechanical properties by creating a larger number of smaller ionic clusters, which act as dynamic cross-links, but are not readily seen by other techniques. Changes in the network structure and morphology of segregated thermolabile ionic domains have an impact on the ionic rearrangement dynamics and, in consequence, on the thermoplastic behavior of these materials at elevated temperatures.

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Section: Introductionmentioning

confidence: 99%

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR

et al. 2014

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“…8,9 The different polarities of the polymer and ionic groups causes nanometre-scale phase separation of the ionic groups in the form of multiplets or clusters. These greatly affect the morphology 10 and increase elasticity. 8 Ionomers have applications as performance coatings, packaging and membranes.…”

Section: Introductionmentioning

confidence: 99%

“…18 Ionomers are normally prepared by casting polymer films from organic solutions. 10,[19][20][21] An emerging ionomer research area involves controlling nanoscale morphology. 22 We recently reported the first example of nanostructured ionomer films consisting of core-shell poly(Bd)/poly(Bdco-MAA) nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Tuning the mechanical properties of nanostructured ionomer films by controlling the extents of covalent crosslinking in core-shell nanoparticles

et al. 2012

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Ionomers are polymers containing a low mole fraction of ionic groups bound to the polymer backbone. These ionic groups produce major changes in their structure and mechanical properties. Recently, we introduced a new family of crosslinked poly(Bd)/poly(Bd-co-MAA) core shell nanoparticles (1,3butadiene and methacrylic acid) that could be ionically crosslinked and cast as nanostructured ionomer films from aqueous dispersions [Pinprayoon et al., Soft Matter, 2011, 7, 247]. The MAA units in the core-shell particles were neutralised by Zn 2+ . Here, we explore the structure-property relationships for these new architecturally controlled nanocomposites by investigating 6 new poly(Bd)/poly (Bd-co-MAA) dispersions and films. In this study we varied the extent of covalent crosslinking in the core and the shell at constant ionic crosslinking for the first time. We used dynamic mechanical thermal analysis to establish a general phase map for the new nanostructured ionomers. Stress-strain data show that our nanostructured films have well controlled, and adjustable, modulus and strain at break values. The data show that the core-shell nanoparticle geometry allows the often observed trade-off between elasticity and ductility to be tuned in a manner that is not possible for conventional ionomers. We show that the chain transfer agent (CTA) concentrations used during the preparation of the nanoparticle cores and shells can be used to independently tune the mechanical properties of the films. This is due to variation of the extents of covalent crosslinking. The results of this study should apply to other covalently crosslinked core-shell nanoparticles containing RCOOH groups in the particle shells.

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“…Down to the length scale of ionic aggregates themselves, while most people observed that the aggregates are spheroidal and on average 2–3 nm in diameter, − others found they may be vesicles of ∼3 nm in shell thickness with diameters of 9–55 and 5–20 nm, nanoplatelets of ∼6 nm in thickness, rods, strings and large percolated networks, etc. Further interior to the ionic aggregates, although nonionic chain segments are assumed to participate, it is generally held that there are essentially ionic groups that coordinate counterions.…”

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Inside the Ionic Aggregates Constrained by Covalently Attached Polymer Chain Segments: Order or Disorder?

Wang

Zhen

et al. 2019

ACS Macro Lett.

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When a small-molecule ionic crystal is group-substituted with polymer chain-segments to form an ionomer, do its constrained ionic aggregates maintain ordered internal structures? This work presents, for a Na-salt sulfonated-polystyrene ionomer, reconciled TEM electron-diffraction schlieren textures and WAXS Bragg-type reflections from the ionic-aggregate nanodomains, which solidly prove the aggregates’ internal (mono)crystalline order. The observed DSC endotherm of the ionomer, identified by WAXS as an order–disorder transition interior to its aggregates, gradually becomes enhanced over a 3-month, room-temperature physical aging process, indicating that the aggregates’ ordering is a slow relaxation process in which the degree of order increases with time. This work corroborates an uncommon form of order, i.e., polymer-bound small-molecule ionic (quasi)crystal, which is supplementary to the order phenomena in small molecules, polymers, and liquid crystals.

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New Insights into Ionic Aggregate Morphology in Zn-Neutralized Sulfonated Polystyrene Ionomers by Transmission Electron Tomography

Cited by 15 publications

References 34 publications

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR

Tuning the mechanical properties of nanostructured ionomer films by controlling the extents of covalent crosslinking in core-shell nanoparticles

Inside the Ionic Aggregates Constrained by Covalently Attached Polymer Chain Segments: Order or Disorder?

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New Insights into Ionic Aggregate Morphology in Zn-Neutralized Sulfonated Polystyrene Ionomers by Transmission Electron Tomography

Cited by 15 publications

References 34 publications

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of 1H Low-Field NMR

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of 1H Low-Field NMR

Tuning the mechanical properties of nanostructured ionomer films by controlling the extents of covalent crosslinking in core-shell nanoparticles

Inside the Ionic Aggregates Constrained by Covalently Attached Polymer Chain Segments: Order or Disorder?

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Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR

Characterization of Network Structure and Chain Dynamics of Elastomeric Ionomers by Means of ¹H Low-Field NMR