The influence of melt processing on the spatial organization of polymer chains in a crystallizable diblock copolymer of nylon 6 and PDMS

Using a layer-multiplying coextrusion process to fabricate films with thousands of alternating polymer nanolayers, we report here a new crystalline morphology in confined polymer nanolayers and an abrupt transition in the crystallization habit. At higher temperatures, poly(ethylene oxide) crystallizes as large, in-plane lamellae. A 5 °C change in the crystallization temperature produces an on-edge lamellar orientation. The results point to a transition from heterogeneous nucleation to substrate-assisted nucleation. This may be a general phenomenon that accounts for previously unexplained differences in the preferred chain alignment of confined polymer crystals.

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Impact of Nanoscale Confinement on Crystal Orientation of Poly(ethylene oxide)

Wang

Keum

Hiltner

et al. 2010

Macromol. Rapid Commun.

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Confined Crystallization of PEO in Nanolayered Films Impacting Structure and Oxygen Permeability

et al. 2009

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Layer-multiplying coextrusion or "forced assembly" of thousands of alternating polystyrene (PS) and poly(ethylene oxide) (PEO) nanolayers was used to study crystallization in a confined, twodimensional space. Atomic force microscopy and small-angle X-ray scattering revealed that as the thickness of the confined PEO layer decreased from the microscale to the nanoscale, the morphology of the PEO changed from three-dimensional spherulites to two-dimensional discoids and to "in-plane" lamellar stacks. Finally, when the confinement occurred on the 25 nm size scale of the usual lamellar thickness, the PEO layers crystallized as single lamellae with large aspect ratio that resembled large single crystals. This crystallization habit imparted more than 2 orders of magnitude reduction in oxygen permeability of the PEO layers. The oxygen permeability directly correlated with the orientation of the lamellar crystals. The dramatic decrease in oxygen permeability arose from a reduction in diffusivity due to increased tortuosity of the diffusion pathway through the oriented lamellae. However, the confined crystalline morphology did not affect the diffusion jump length of oxygen molecules, as reflected by the constant activation energy regardless of the layer thickness. At 85% relative humidity, the moisture sorption of PEO layers was consistently about 8%, independent of the layer thickness. Nevertheless, the lamellar orientation was not affected, and the dramatic decrease in PEO permeability was preserved.

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Preparation of Monomer Casting Nylon-6-b-Polydimethylsiloxane Copolymers with Enhanced Mechanical and Surface Properties

Ying

Wang

Xing

et al. 2017

Polymer-Plastics Technology and Engineering

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The influence of melt processing on the spatial organization of polymer chains in a crystallizable diblock copolymer of nylon 6 and PDMS

Cited by 5 publications

References 19 publications

Impact of Nanoscale Confinement on Crystal Orientation of Poly(ethylene oxide)

Impact of Nanoscale Confinement on Crystal Orientation of Poly(ethylene oxide)

Confined Crystallization of PEO in Nanolayered Films Impacting Structure and Oxygen Permeability

Preparation of Monomer Casting Nylon-6-b-Polydimethylsiloxane Copolymers with Enhanced Mechanical and Surface Properties

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