Stability and phase behavior of the poly(ethylene oxide)–urea complexes prepared by electrospinning

Liu, Yang; Pellerin, Christian

doi:10.1016/j.polymer.2009.03.050

Cited by 22 publications

(22 citation statements)

References 35 publications

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“…The 13 C line widths for PEO and UREA signals did not change with the doping. Additionally, DSC scan also showed the characteristic melting peak corresponding to the supramolecular crystals at 416 K, 20 with melting of some excess UREA crystals at 407 K ( Figure 1c). These structural results and T 1H behaviors suggest that the Cu(II)-AA molecules simply attach to the surface and reduce the T 1H value due to a fast spin diffusion into the interior region without disturbing the bulk structures and thermal properties.…”

mentioning

confidence: 97%

Dynamic Geometry and Kinetics of Polymer Confined in Self-Assembly via Cooperative Hydrogen Bonding: A Solid-State NMR Study under Paramagnetic Doping

Miyoshi

2010

Macromolecules

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Well-defined arrangements of the secondary intermolecular interactions play important roles for the design of new materials, which leads to unique self-assemblies consisting of multicomponent molecules with different sizes and shapes. Much work has gone into characterizing the static structures of such selfassembled systems. 1 Cooperative secondary interactions influence the molecular dynamics of the components and the bulk properties. Therefore, understanding relationship between microscopic dynamics and secondary interactions in self-assemblies is an important subject in this field. 2 Poly(ethylene oxide) (PEO) is a hydrogen acceptor and can form supramolecular crystals with a small molecule of UREA, which is a hydrogen donor, in methanol solutions. XRD revealed that two-thirds of the UREA molecules form nanochannels with a diameter of ∼1 nm, inside which isolated PEO chains and the remaining UREA molecules are included ( Figure 1a). 3 Several groups have investigated PEO dynamics in this unique morphology by conventional NMR relaxation measurements and have suggested that the dynamics of PEO is restricted by cooperative hydrogen bonding. 4,5 However, the details of the geometry and kinetics of the molecular dynamics of PEO in this supramolecular system are not well understood.Solid-state (SS) NMR techniques using magnetically anisotropic interactions can provide not only the kinetics and but also the geometry of the molecular dynamics. 6 In the past decade, various sophisticated SS-NMR techniques have been developed to investigate molecular dynamics in a wide frequency range in natural abundance. 7-11 Among them, center bands only detection of exchange (CODEX) 7,8 NMR can provide both the geometry and kinetics of molecular dynamics in a slow range and has been successfully applied to investigate the molecular dynamics of small molecules, 7 polymers, 12-14 liquid crystals, 15 and polymer blends. 16 However, this robust technique suffers from low NMR sensitivity, which has limited its application in chemically complex systems and/or systems with long T 1H values. Recently, Wickramasinghe et al. proposed a simple approach using paramagnetic doping for sensitivity enhancement. 17 Adding a small amount of a paramagnetic compound into a protein crystal could effectively shorten the T 1H value without disturbing the structures. Similar strategies may be applicable to self-assemblied systems. In this Communication, CODEX NMR and paramagnetic doping have been used to elucidate the dynamic nature of PEO in a PEO-UREA supramolecular system in natural abundance. Figure 1a shows the 13 C CPMAS NMR spectrum for PEO-UREA supramolecules at 213 K and their structures. PEO shows a very sharp 13 C signal at 70 ppm. The single resonance supports the result the PEO chains adopt a uniform 4 1 helical conformation which was obtained by XRD. 3 The observed single resonance is in stark contrast to a bulk PEO signal, which has multiple splitting on its 13 C signal (Figure 2b). Using 13 C-13 C double quantum NMR combined with relaxation...

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confidence: 97%

Dynamic Geometry and Kinetics of Polymer Confined in Self-Assembly via Cooperative Hydrogen Bonding: A Solid-State NMR Study under Paramagnetic Doping

Miyoshi

2010

Macromolecules

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“…Electrospinning has therefore been mostly applied to concentrated solutions of polymers, polymer blends, and composites that have sufficiently flexibility and high molecular weight to create a well‐entangled network in solution . In the last few years, our group has shown that hydrogen‐bonded supramolecular complexes between a polymer, such as poly(ethylene oxide) (PEO), and small molecules can readily be electrospun . Efficient complexation and crystallization was observed for systems forming intercalates and inclusion complexes, even if the solvent evaporation occurs on a millisecond time scale.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4] In the last few years, our group has shown that hydrogen-bonded supramolecular complexes between a polymer, such as poly(ethylene oxide) (PEO), and small molecules can readily be electrospun. [5,6] Efficient complexation and crystallization was observed for systems forming intercalates and inclusion complexes, even if the solvent evaporation occurs on a millisecond time scale. The electrospinning of inclusion complexes of polymers with cyclodextrin and of clathrates of syndiotactic polystyrene has also been demonstrated recently.…”

Section: Introductionmentioning

confidence: 99%

Electrospinning of Ionic Supramolecular Azo Complexes

Wang

Zhang

Bazuin

et al. 2014

Macromolecular Symposia

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Summary Electrospinning was applied to DMF solution mixtures of poly(methyl methacrylate) (PMMA) and MO/PVP, which is an azo‐containing liquid crystalline complex between methyl orange (MO) and methylated poly(4‐vinyl pyridine) (PVP), to obtain composite light‐responsive fibers. The average diameter of the fibers, which ranged from 700 nm to 1.5 µm, increases with PMMA content. Differential scanning calorimetry, X‐ray diffraction and transmission electron microscopy show that they are microphase separated in the form of interspersed nanostrips of PMMA‐rich and MO/PVP(‐rich) phases. The MO/PVP(‐rich) phase is liquid crystalline (smectic A) as in the bulk, but with no orientation relative to the fiber axis. The birefringence of the fibers observed by polarized optical microscopy is attributed, at least in part, to form birefringence. This study is promising for the preparation of light‐responsive fibers based on easy‐to‐prepare polymer complexes.

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“…Some parts of the β-phase complexes can be transformed into α-phase complexes by increasing the urea mole fraction or by heating. The β-α transition of PEO-urea complexes and their structural phase diagrams have been intensively studied [2,[5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Electrical Characteristics of Poly(ethylene oxide)-urea Complex Films

Cho¹,

Cho²,

Kim³

2012

Transactions on Electrical and Electronic Materials

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The electrical characteristics of complex films composed of poly(ethylene oxide) (PEO) and urea as a function of the urea concentration were examined in this study. Moreover, their structural characteristics were also compared. Depending on the urea concentration, the structural phases were classified as PEO+β-phase composite, β-phase+α-phase composites, or α-phase composite+urea. At urea concentrations below ~0.064 M, the β-phase was dominant in the complex film. Moreover, the conductance increased rapidly with an increase in the urea concentration. For urea concentrations ranging from ~0.064 to ~0.25 M, the β-phase was gradually substituted by the α-phase. As the film was composed entirely of the α-phase at urea concentrations greater than ~0.25 M, its conductance was decreased. In this study, the electrical characteristics observed for the different phases are analyzed and discussed.

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Stability and phase behavior of the poly(ethylene oxide)–urea complexes prepared by electrospinning

Cited by 22 publications

References 35 publications

Dynamic Geometry and Kinetics of Polymer Confined in Self-Assembly via Cooperative Hydrogen Bonding: A Solid-State NMR Study under Paramagnetic Doping

Dynamic Geometry and Kinetics of Polymer Confined in Self-Assembly via Cooperative Hydrogen Bonding: A Solid-State NMR Study under Paramagnetic Doping

Electrospinning of Ionic Supramolecular Azo Complexes

Electrical Characteristics of Poly(ethylene oxide)-urea Complex Films

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