Effect of PEO molecular weight on the miscibility and dynamics in epoxy/PEO blends

Lu, Shoudong; Zhang, Rongchun; Wang, Xiaoliang; Sun, Pingchuan; Liu, Weifeng; Liu, Qingjie; Jia, Ning

doi:10.1140/epje/i2015-15118-0

Cited by 8 publications

(3 citation statements)

References 64 publications

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“…It has always been a challenging and tempting goal to fabricate high performance polymer materials with a good balance of modulus, elongation, and breaking strength, and thus render the materials to be stiff while at the same time being tough. − Therefore, polymer blend has become a pretty straightforward approach to address the above challenges, since it could combine both the merits of two different bulk materials. However, simply blending usually does not work, as the achievement of superior mechanical properties is strongly related with specific polymer conformations, hierarchical structures, and the miscibility between different components, which generally relies on the intermolecular interactions, such as hydrogen bonds, van der Waals interactions, electrostatic interactions, and so on. − Herein, elucidating the polymer conformations and intermolecular interactions will provide significant insights into the microscopic origin of the enhanced mechanical properties of polymer blends.…”

Section: Introductionmentioning

confidence: 99%

Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective

Tian

Zhang

et al. 2017

J. Phys. Chem. B

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Fabricating materials with excellent mechanical performance from the natural renewable and degradable biopolymers has drawn significant attention in recent decades due to the environmental concerns and energy crisis. As two of the most promising substitutes of synthetic polymers, silk fibroin (SF), and cellulose, have been widely used in the field of textile, biomedicine, biotechnology, etc. Particularly, the cellulose/SF blend film exhibits better strength and toughness than that of regenerated cellulose film. Herein, this study is aimed to understand the molecular origin of the enhanced mechanical properties for the cellulose/SF blend film, using solid-state NMR as a main tool to investigate the conformational changes, intermolecular interactions between cellulose and SF and the water organization. It is found that the content of the β-sheet structure is increased in the cellulose/SF blend film with respect to the regenerated SF film, accompanied by the reduction of the content of random coil structures. In addition, the strong hydrogen bonding interaction between the SF and cellulose is clearly elucidated by the two-dimensional (2D) H-C heteronuclear correlation (HETCOR) NMR experiments, demonstrating that the SF and cellulose are miscible at the molecular level. Moreover, it is also found that the -NH groups of SF prefer to form hydrogen bonds with the hydroxyl groups bonded to carbons C2 and C3 of cellulose, while the hydroxyl groups bonded to carbon C6 and the ether oxygen are less favorable for hydrogen bonding interactions with the -NH groups of SF. Interestingly, bound water is found to be present in the air-dried cellulose/SF blend film, which is predominantly associated with the cellulose backbones as determined by 2D H-C wide-line-separation (WISE) experiments with spin diffusion. This clearly reveals the presence of nanoheterogeneity in the cellulose/SF blend film, although cellulose and SF are miscible at a molecular level. Without doubt, these in-depth atomic-level structural information could help reveal the molecular origin of the enhanced mechanical properties of the blend film, and thus to establish the structure-property relationship, which could further provide guidance for the fabrication of high performance biopolymer-based materials.

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Section: Introductionmentioning

confidence: 99%

Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective

Tian

Zhang

et al. 2017

J. Phys. Chem. B

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“…mechanical and rheological) can be optimized. [66][67][68][69] In this study, we further demonstrated the robust performance of the proposed pulse sequences on polymer blend PMMA/PB; their chemical structures are shown in Figure 1. PMMA is a semi-crystalline polymer with glass transition (Tg) and melting (Tm) temperatures both above 100 o C, whereas PB is a viscous liquid with a Tg of ~ -90 o C. Therefore, in the PMMA/PB blend, PMMA is considered as the rigid and PB is the mobile components.…”

Section: Resultsmentioning

confidence: 60%

Exploiting heterogeneous time scale of dynamics to enhance 2D HETCOR solid-state NMR sensitivity

Zhang

Nishiyama

Ramamoorthy

2019

Journal of Magnetic Resonance

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Multidimensional solid-state NMR spectroscopy plays a significant role in offering atomic-level insights into molecular systems. In particular, heteronuclear chemical shift correlation (HETCOR) experiments could provide local chemical and structural information in terms of spatial heteronuclear proximity and through-bond connectivity. In solid state, the transfer of magnetization between heteronuclei, a key step in HETCOR experiments, is usually achieved using cross-polarization (CP) or INEPT (insensitive nuclei enhanced by polarization transfer) depending on the sample characteristics and magic-angle-spinning (MAS) frequency. But, for a multiphase system constituting molecular components that differ in their time scales of mobilities, CP efficiency is pretty low for mobile components because of the averaging of heteronuclear dipolar couplings whereas INEPT is inefficient due to the short T2 of immobile components and can be non-selective due to strong proton spin diffusion for immobile components especially under moderate spinning speeds. Herein, in this study we present two 2D pulse sequences that enable the sequential acquisition of 13 C/ 1 H HETCOR NMR spectra for the rigid and mobile components by taking full advantage of the abundant proton magnetization in a single experiment with barely increasing the overall experimental time. In particular, the 13 C-detected HETCOR experiment could be applied under slow MAS conditions, where a multiple-pulse sequence is typically employed to enhance 1 H spectral resolution in the indirect dimension. In contrast, the 1 H-detected HETCOR experiment should be applied under ultrafast MAS, where CP and transient heteronuclear nuclear Overhauser effect (NOE) polarization transfer are combined to enhance 13 C signal intensities for mobile components. These pulse sequences are experimentally demonstrated on two model systems .

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“…For preparing the PHBH/PCL blend by solution casting, PCL of M n 10 kDa was preferred because low-molecular-weight polymers have higher chances of interacting with other polymers. , The photograph of the resulting unheated PHBH/PCL blend film (Supplementary Figure S7) showed a spiderweb-like pattern, indicating the heterogeneous, macroscale phase separation of the two polymers. This suggests that the two polymers are not completely miscible, although the blend film appears macroscopically smooth and homogeneous after heat pressing (data not shown).…”

Section: Resultsmentioning

confidence: 99%

Heat-Press Technique for Coating Ammonium Nitrate Granules with Biodegradable Hydrophobic Polymer Blend of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and Poly(ε-caprolactone)

Ezema

Ooi

Matsumoto

2022

ACS Agric. Sci. Technol.

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The use of coated nitrogen fertilizers increases nitrogen use efficiency by reducing the nutrient's loss to the environment through ammonia volatilization, leaching, and denitrification. Biodegradable polymers are the preferred coating materials because they are consumed and eventually mineralized by microbes, which minimizes pollution. In this study, two biodegradable hydrophobic polymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and poly(ε-caprolactone) (PCL), were used to coat ammonium nitrate (NH 4 NO 3 ) granules using a heat-press technique that, for the first time, eliminated the need for organic solvents at the coating stage. With a polymer coating weight content of 8.6%, the release of nitrate ions (NO 3 − ) into water from PCL-coated fertilizers was very fast (approximately 90% in 1 week), whereas there was no release of NO 3 − from the PHBH-coated fertilizers until after 10 weeks. The NO 3 − release rate, the water vapor permeability, and the Young's modulus of the polymer coatings were regulated by blending PHBH and PCL (80:20 weight ratio). The controlled release of NO 3 − was also maintained in biologically active soil; biodegradation of the coatings resulted in no burst release of NO 3 − over the time period tested. These results demonstrated that PHBH, PCL, or their blend, when applied to the surface of NH 4 NO 3 granules using a heat-press technique, could effectively control nutrient release rate.

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Effect of PEO molecular weight on the miscibility and dynamics in epoxy/PEO blends

Cited by 8 publications

References 64 publications

Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective

Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective

Exploiting heterogeneous time scale of dynamics to enhance 2D HETCOR solid-state NMR sensitivity

Heat-Press Technique for Coating Ammonium Nitrate Granules with Biodegradable Hydrophobic Polymer Blend of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and Poly(ε-caprolactone)

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