Correlation between Morphology and Mechanical Properties in Zn‐Neutralized Sulfonated Polystyrene Ionomer/Poly(ethylene glycol) Blends: Contribution of EFTEM

Abstract

Relationships between microstructure and mechanical properties in SPS‐Zn/PEG blends are investigated. Ion/dipole interactions induce the miscibility of both blend components for PEG content up to 10 wt.‐% as evidenced by DSC and TEM observations. Elemental mapping by EFTEM was used to investigate the ionic cluster microstructure and the phase structure in the blends. PEG chains do not hinder the formation of ionic multiplets but modify the microstructure of the clusters. Moreover, a PEG‐rich layer is observed in the vicinity of the aggregates surface. As a consequence, no cluster glass transition is observed in DMA experiments for these blend systems and besides, the absence of ionic plateau is assigned to the decrease in the ionic clusters' stability.magnified image

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

“…7,12 These aggregates appear heterogeneously dispersed within the polystyrene matrix and tend to form a network. In contrast, and as already described in a previous study, 27 the morphology of the ionic aggregates is quite different in the C SPS-Zn film. The shape of the ionic aggregates appears to be strongly anisotropic, with nanoscopic rodlike structures about 5À10 nm thick and 50À100 nm long observed in Figure 1b.…”

“…Randomly sulfonated polystyrene (SPS) was prepared by solution sulfonation of PS in dichloromethane using sulfate acetyl as sulfonation agent according to the procedure described by Makowski et al 26 and elsewhere. 27 A sulfonation degree of about 3 mol % was measured by titration with methanolic NaOH. SPS-Zn was prepared by adding a methanolic solution of zinc acetate dropwise to a stirred 10% (w:v) solution of SPS (in a 9:1 (v:v) toluene/methanol mixture).…”

“…Purity of the PS was checked by SEC (size exclusion chromatography) and NMR (nuclear magnetic resonance). Randomly sulfonated polystyrene (SPS) was prepared by solution sulfonation of PS in dichloromethane using sulfate acetyl as sulfonation agent according to the procedure described by Makowski et al and elsewhere . A sulfonation degree of about 3 mol % was measured by titration with methanolic NaOH.…”

Visualization of clusters in polymer electrolyte membranes by electron microscopy

“…Dalmas et al 31 prepared Zn-neutralized samples of PSS and obtained BF TEM images showing a highly nonuniform distribution of thin, curved features with various lengths approaching several hundred nanometers, which the authors interpreted as ionic aggregates. High resolution images presented in this paper also show a network of nanometer sized spots uniformly distributed in the material.…”

Comparison of the mechanical properties of styrene-based ionomers containing either crown ether or pentaethylene glycol with those of underneutralized ionomers

“…In the case of Zn‐neutralized sulfonated styrene ionomers containing poly(ethylene glycol) (PEG), it was found that the PEG did not inhibit but altered the multiplet formation. As a result, cluster T g and ionic plateau were not observed, suggesting the cluster plasticization …”