Synthesis and Properties of SEPS-g-PEO Copolymers with Varying Branch Lengths

Zhao, Zhongfu; Liu, Pei-Ying; Zhang, Chunqing; Liu, Wei; Wang, Yanhui; Tang, Tao; Ding, Yifu; Zhang, Yandong; Meng, Fanzhi

doi:10.1007/s10118-018-2104-0

Cited by 5 publications

(5 citation statements)

References 35 publications

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“… 55 In comparison, the CHMOH10:0 does not possess highly ordered structures according to the SAXS measurements, which is a result of the simultaneous solution casting and cross‐linking process used to form the membranes. However, the correlation length matches well with the reported value in Reference48. TEM measurement (Figure 2(b)) of CHMOH10:0 reveals PS cylinders (darker regions due to the RuO 4 staining) with diameter ∼ 8.3 nm dispersed in the PEB phases (bright regions).…”

Section: Resultssupporting

confidence: 90%

“…Another issue is the low content of PS phase in the SEBS AEMs. Since commercial SEBS copolymers were initially designed as thermoplastic elastomers for various applications, such as adhesives, sealants, coats, footwear and automotive parts, they mostly have a 20 ∼ 40 wt% of PS content 48–50 . As the ion‐conducting domains, the functionalized PS phase theoretically should occupy a sufficiently high proportion in SEBS AEMs for high IEC values and ideal conductivity.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene

Shi

Meng

Zhao

et al. 2021

J of Applied Polymer Sci

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Hybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene‐b‐[ethylene‐co‐butylene]‐b‐styrene) (SEBS) copolymers and low molecular weight homo‐polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella‐like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and Tg of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene

Shi

Meng

Zhao

et al. 2021

J of Applied Polymer Sci

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“…However, in these previous studies, the grafting density varied when the molecular weight of the grafted chains increased, and the effect of the two structural factors had not been explored independently so far. Less attention has been paid to the confined crystallization behavior imposed by grafting density and molecular weight of the grafted polymers on the SiO 2 surface, whereas these effects have been extensively reported for polymers confined in other systems, such as carbon nanotubes and block copolymers with grafted brushes. , …”

Section: Introductionmentioning

confidence: 99%

“…Less attention has been paid to the confined crystallization behavior imposed by grafting density and molecular weight of the grafted polymers on the SiO 2 surface, whereas these effects have been extensively reported for polymers confined in other systems, such as carbon nanotubes 24 and block copolymers with grafted brushes. 27,28 Poly(ethylene oxide) is an attractive semicrystalline polymer for fundamental research, 29,30 and its silica nanocomposites can increase ion conductivity for applications in solid-state lithium batteries materials. 31,32 The main goal of this paper is to systematically study the effect of changing grafting density, molecular weight, and silica content on the crystallization behavior of grafted methoxypoly(ethylene glycol) (MPEG) chains.…”

Section: ■ Introductionmentioning

confidence: 99%

Correlation between Grafting Density and Confined Crystallization Behavior of Poly(ethylene glycol) Grafted to Silica

Wen

Shui

et al. 2019

Macromolecules

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The interfacial interactions of polymer-nanoparticles have dramatical effects on the crystallization behavior of grafted polymers. In this study, methoxy polyethylene glycol (MPEG) (molecular weights 750, 2000 and 4000 g mol −1 ) was grafted onto amino-modified nanosized silica (SiO2-NH2) by the "grafting to" method. The effects of the grafting density and molecular weight on the confined crystallization of grafted MPEG (MPEG-g-SiO2) were systematically investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide-angle X-ray scattering (WAXS). It was found that confinement effects are stronger when lower molecular weights of grafted MPEG are employed. These grafted MPEG chains are more difficult to stretch out on SiO2-NH2 surfaces than when they are free in the bulk polymer. Both crystallization temperature (Tc) and crystallinity of grafted MPEG chains decrease with reductions of grafting density. Additionally, covalent bonding effects and interfacial interaction confinement effects are strengthened by the decrease in grafting density, leading to an increase in decomposition temperature and to the disappearance of the self-nucleation Domain (i.e., Domain II), when self-nucleation experiments are performed by DSC. Overall isothermal crystallization kinetics was studied by DSC and the results were analyzed with the Avrami equation. An Avrami index of n≈3 was obtained for neat MPEG (indicating that instantaneous spherulites are formed). However, in the case of MPEG-g-SiO2 with the lowest grafting density, the Avrami index of (n) was less than 1 (first order kinetics or lower), indicating that nucleation is the determining factor of the overall crystallization kinetics, a signature for confined crystallization. At the same time, the crystallization from the melt for this MPEG-g-SiO2 with the lowest grafting density occurs at Tc≈-30 ºC, a temperature close to the glass transition temperature (Tg) of MPEG, indicating that this confined MPEG crystallizes from homogeneous nuclei.

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“…Initially, commercial SEBS was designed as thermoplastic elastomers for various applications such as adhesives, sealants, coats, footwear, and automotive parts, in which poly(styrene- b -(butadiene)- b -styrene) (SBS) with a low content of 1,4-butadiene units was hydrogenated. − Its rubbery PEB phase occupies a high proportion of SEBS but hardly contributes to the ion transport performance and dimensional stability of SEBS based AEMs. In designing ideal SEBS based AEMs, we envision that the cross-linking structures are introduced into the PEB phase rather than into the PS phase so that the PEB and PS phase are responsible for the dimensional stability and ion conductivity, respectively.…”

Section: Introductionmentioning

confidence: 99%

Physically Self-Cross-Linked SEBS Anion Exchange Membranes

et al. 2020

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Two kinds of commercially available poly(styrene-b-butadiene-b-styrene) copolymers (SBS1301 and SBS1401) with 86−87% of 1,4-butadiene units were modified to fabricate robust poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) anion exchange membranes (AEMs) via sequential hydrogenation, chloromethylation, quaternization, and alkalization. Its poly(ethyleneco-butylene) phase could provide a physically self-cross-linked structure responsible for the mechanical stability of AEMs, due to the crystalline behavior (T m = ∼80 °C and ∼20% of crystallinity) of polyethylene segments after the hydrogenation of 1,4-butadiene units. The polystyrene phase was liberated from the chemical cross-linking structures to focus on conducting ion transport. Different from commercial SEBS based AEMs, this specially designed microphase separation structure led to low swelling ratio, high water uptake, and good hydroxide conductivity (e.g., ∼12%, ∼80%, ∼81 mS cm −1 at 80 °C) at moderate ion exchange capacity (IEC = 1.48 mmol g −1 ) for the SEBS1401-OH AEMs made from SBS1401. The single cell using SEBS1401-OH has a peak power density as high as 320 mW cm −2 while the current density achieves 860 mA cm −2 . These results indicate that the proposed method can develop high-performance SEBS based AEMs, suitable for fuel cell applications.

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Synthesis and Properties of SEPS-g-PEO Copolymers with Varying Branch Lengths

Cited by 5 publications

References 35 publications

Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene

Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene

Correlation between Grafting Density and Confined Crystallization Behavior of Poly(ethylene glycol) Grafted to Silica

Physically Self-Cross-Linked SEBS Anion Exchange Membranes

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