Kinetics of demixing and remixing in poly(ethylene oxide)/poly(ether sulphone) blends as studied by modulated temperature differential scanning calorimetry

Swier, Steven; Pieters, Ronny; Mele, Bruno Van

doi:10.1016/s0032-3861(02)00177-5

Cited by 32 publications

(50 citation statements)

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“…The atomistic PEO models used here have been tested before to generate densities and viscosities in good agreement with experiments. 35 Assuming the glass transition of the atomistic oligomers is similar to what is found in experiments, the glass transition temperature is expected to be below 200 K. 9,46 The higher slope for atomistic PEO at low temperature, as seen in Fig. 7, is thus not caused by proximity to the glass transition.…”

Section: A Bulk Oligomersmentioning

confidence: 53%

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

Hong

Chremos

Panagiotopoulos

2012

The Journal of Chemical Physics

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Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix J. Chem. Phys. 134, 194906 (2011) Coarse-grained models of poly(ethylene oxide) oligomer-grafted nanoparticles are established by matching their structural distribution functions to atomistic simulation data. Coarse-grained force fields for bulk oligomer chains show excellent transferability with respect to chain lengths and temperature, but structure and dynamics of grafted nanoparticle systems exhibit a strong dependence on the core-core interactions. This leads to poor transferability of the core potential to conditions different from the state point at which the potential was optimized. Remarkably, coarse graining of grafted nanoparticles can either accelerate or slowdown the core motions, depending on the length of the grafted chains. This stands in sharp contrast to linear polymer systems, for which coarse graining always accelerates the dynamics. Diffusivity data suggest that the grafting topology is one cause of slower motions of the cores for short-chain oligomer-grafted nanoparticles; an estimation based on transition-state theory shows the coarse-grained core-core potential also has a slowing-down effect on the nanoparticle organic hybrid materials motions; both effects diminish as grafted chains become longer.;

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Section: A Bulk Oligomersmentioning

confidence: 53%

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

Hong

Chremos

Panagiotopoulos

2012

The Journal of Chemical Physics

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“…Experimentally, pure poly(ethylene oxide) has a T g z À67 C. 49 NIMs systems have measured T g 's for SiO 2 cores with tertiary amines of À66 C 27 and for ZrO 2 cores with linear…”

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confidence: 99%

Diffusivities, viscosities, and conductivities of solvent-free ionically grafted nanoparticles

Hong

Panagiotopoulos

2013

Soft Matter

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A new class of conductive composite materials, solvent-free ionically grafted nanoparticles, were modeled by coarse-grained molecular dynamics methods. The grafted oligomeric counterions were observed to migrate between different cores, contributing to the unique properties of the materials. We investigated the dynamics by analyzing the dependence on temperature and structural parameters of the transport properties (self-diffusion coefficients, viscosities and conductivities) and counterion migration kinetics. Temperature dependence of all properties follows the Arrhenius equation, but chain length and grafting density have distinct effects on different properties. In particular, structural effects on the diffusion coefficients are described by the Rouse model and the theory of nanoparticles diffusing in polymer solutions, viscosities are strongly influenced by clustering of cores, and conductivities are dominated by the motions of oligomeric counterions. We analyzed the migration kinetics of oligomeric counterions in a manner analogous to unimer exchange between micellar aggregates. The counterion migrations follow the "double-core" mechanism and are kinetically controlled by neighboring-core collisions.

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“…MTDSC is not only suitable for studying vitrification and glass transitions resulting from phase separation, but also for gaining a unique in situ insight into the kinetics of demixing and remixing in partially miscible polymer blends [24,25] and solutions. [26][27][28][29] During temperature-induced phase separation, mixing and/or demixing occur during each temperature modulation cycle and their heat effects contribute to the observed heat capacity signal, which is therefore termed an apparent heat capacity.…”

Section: Introductionmentioning

confidence: 99%

“…For polymer blends, this was illustrated for poly(ethylene oxide)/poly(ether sulfone) (PEO/PES) blends, showing the effects of blend composition and constituent molar mass on the demixing and remixing kinetics and the interrelation between both components. [24,25] This MTDSC methodology was extended to real-time observation of reaction-induced phase separation (RIPS). For low-T g modifiers, the heat effects associated with phase separation contribute to the heat capacity signal, enabling the real-time measurement of the cloud point during RIPS.…”

Section: Introductionmentioning

confidence: 99%

“…For low-T g modifiers, the heat effects associated with phase separation contribute to the heat capacity signal, enabling the real-time measurement of the cloud point during RIPS. [30,31] Herein, the methodology for studying the PEO/PES system by using MTDSC [24,25] is applied to a blend consisting of a random copolymer of ethylene oxide and propylene oxide, P(EO-ran-PO), and PES. The introduction of the propylene oxide comonomer reduces the miscibility and gives rise to an even smaller enthalpy of demixing for P(EO-ran-PO)/PES (less than 1 J g À1 ) when compared to the PEO/PES system (less than 2 J g À1 ).…”

Section: Introductionmentioning

confidence: 99%

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Phase Behavior in Blends of Ethylene Oxide–Propylene Oxide Copolymer and Poly(ether sulfone) Studied by Modulated‐Temperature DSC and NMR Relaxometry

Lokeren¹,

Gotzen²,

Pieters³

et al. 2009

Chemistry A European J

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The state diagram of a blend consisting of a copolymer containing ethylene oxide and propylene oxide, P(EO-ran-PO), and poly(ether sulfone), PES, is constructed by using modulated-temperature differential scanning calorimetry (MTDSC), T(2) NMR relaxometry, and light scattering. The apparent heat capacity signal in MTDSC is used for the characterization of polymer miscibility and morphology development. T(2) NMR relaxometry is used to detect the onset of phase separation, which is in good agreement with the onset of phase separation in the apparent heat capacity from MTDSC and the cloud-point temperature as determined from light scattering. The coexistence curve can be constructed from T(2) values at various temperatures by using a few blends with well-chosen compositions. These T(2) values also allow the detection of the boundary between the demixing zones with and without interference of partial vitrification and are in good agreement with stepwise quasi-isothermal MTDSC heat capacity measurements. Important interphases are detected in the heterogeneous P(EO-ran-PO)/PES blends.

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Kinetics of demixing and remixing in poly(ethylene oxide)/poly(ether sulphone) blends as studied by modulated temperature differential scanning calorimetry

Cited by 32 publications

References 20 publications

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

Diffusivities, viscosities, and conductivities of solvent-free ionically grafted nanoparticles

Phase Behavior in Blends of Ethylene Oxide–Propylene Oxide Copolymer and Poly(ether sulfone) Studied by Modulated‐Temperature DSC and NMR Relaxometry

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