Influence of morphology on the transport properties of polystyrene/polybutadiene blends: 2. Modelling results

Shah, N.; Sax, J.E.; Ottino, Julio M.

doi:10.1016/0032-3861(85)90260-5

Cited by 20 publications

(13 citation statements)

References 11 publications

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“…This is in contrast to what is typically observed in uncharged block copolymers: samples with symmetric composition (i.e., with the volume fraction of each block in the vicinity of 0.5) exhibit a lamellar morphology, in the dry state or when swollen with selective solvents. ,, The presence of a cylindrical morphology in hydrated pNeh 9 - b -pNpm 9 is thus interesting. Such morphologies have been seen before in nearly symmetric sulfonated block copolymers and are predicted by theories on charged block copolymers. , In these systems, ,, the charged block forms the matrix. We thus expect the matrix of wet pNeh 9 - b -pNpm 9 to comprise hydrated pNpm, while the cylinders are expected to comprise dry pNeh chains.…”

Section: Resultssupporting

confidence: 69%

“…Such morphologies have been seen before in nearly symmetric sulfonated block copolymers 24 and are predicted by theories on charged block copolymers. 51 , 52 In these systems, 24 , 54 , 55 the charged block forms the matrix. We thus expect the matrix of wet pNeh 9 - b -pNpm 9 to comprise hydrated pNpm, while the cylinders are expected to comprise dry pNeh chains.…”

Section: Resultsmentioning

confidence: 99%

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Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

Sun

Jiang²,

Siegmund

et al. 2016

Macromolecules

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Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

Sun

Jiang²,

Siegmund

et al. 2016

Macromolecules

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“…In addition to the chain flexibility and free volume, polymer morphology in block copolymers also significantly affects the diffusion of gas molecules. 36 This is especially true for polyurethanes as they tend to microphase separate into different morphologies, including a continuous phase with spheres, cylinders, and lamellae. 37 The exact morphology depends on the miscibility of the blocks of the copolymer, stoichiometry of the blocks, and the preparation conditions (including thermal history).…”

Section: Resultsmentioning

confidence: 99%

“…In addition to the chain flexibility and free volume, polymer morphology in block copolymers also significantly affects the diffusion of gas molecules . This is especially true for polyurethanes as they tend to microphase separate into different morphologies, including a continuous phase with spheres, cylinders, and lamellae .…”

Section: Resultsmentioning

confidence: 99%

Transport of Nitric Oxide (NO) in Various Biomedical grade Polyurethanes: Measurements and Modeling Impact on NO Release Properties of Medical Devices

Ren

Bull

Meyerhoff

2016

ACS Biomater. Sci. Eng.

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Nitric oxide (NO) releasing polymers are promising in improving the biocompatibility of medical devices. Polyurethanes are commonly used to prepare/fabricate many devices (e.g., catheters); however, the transport properties of NO within different polyurethanes are less studied, creating a gap in the rational design of new NO releasing devices involving polyurethane materials. Herein, we study the diffusion and partitioning of NO in different biomedical polyurethanes via the time-lag method. The diffusion of NO is positively correlated with the PDMS content within the polyurethanes, which can be rationalized by effective media theory considering various microphase morphologies. Using catheters as a model device, the effect of these transport properties on the NO release profiles and the distribution around an asymmetric dual lumen catheter are simulated using finite element analysis and validated experimentally. This method can be readily applied in studying other NO release medical devices with different configurations.

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“…Previous experimental studies of CO 2 sorption in such systems conducted near [132][133][134][135][136][137][138][139][140][141][142] or just above atmospheric pressure (<2.5 MPa), [134,[143][144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161] as well as efforts aimed at modeling CO 2 transport in such systems, [162][163][164] are not considered here because of the low pressures employed. However, several studies [165][166][167][168][169][170] have exposed polymer blends to CO 2 at considerably higher pressures, and we briefly mention some of these results here.…”

Section: Sorption Behaviormentioning

confidence: 99%

Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide

2008

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Environmentally‐responsible materials processing is becoming an important global consideration in a wide variety of technologies, especially those wherein volatile and/or residual organic solvents cannot be tolerated. In this context, polymer processing has benefited tremendously from advances achieved using high‐pressure CO2 as a viscosity modifier, plasticizing agent, foaming agent, and reaction medium. Pressurized CO2 is environmentally benign, inexpensive, sustainable, and versatile owing to its gas‐like viscosity and liquid‐like solubility, which can be tuned through judicious choice of temperature and pressure. The addition of high‐pressure CO2 to homopolymer blends and block copolymers can have a profound impact on polymer thermodynamics and kinetic processes since the number of interacting species increases. As a result, the compressibility as well as plasticization and intermolecular screening effects become non‐negligible. In this work, we review how these factors influence such polymeric systems, and discuss commercial polymer processes and applications that benefit from the use of high‐pressure CO2.

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Influence of morphology on the transport properties of polystyrene/polybutadiene blends: 2. Modelling results

Cited by 20 publications

References 11 publications

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

Transport of Nitric Oxide (NO) in Various Biomedical grade Polyurethanes: Measurements and Modeling Impact on NO Release Properties of Medical Devices

Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide

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