Direct imaging of polyethylene crystallites within block copolymer microdomains

Polymer Crystallization Confined in One, Two, or Three Dimensions

“…TEM micrographs of E/VCH 10/26, a cylinder-forming polymer similar to E/VCH 6/25, have also been published previously; 16 they show ribbonlike crystals of E running along the cylinder axis. Here, we turn to the lamellar and gyroid cases.…”

“…In the case of the sphere-forming E/VCH 5/22 (Figure a), the q / q * = √3 peak expected for a bcc lattice is visible only as a weak shoulder, because the form factor for scattering from spheres of the appropriate diameter (dashed curve in Figure a) has a minimum in this vicinity . After E block crystallization, the electron density within the E domains is no longer uniform, nor is it precisely the same from one domain to the next; this can be seen directly in a published TEM image of E/VCH 5/22, which shows that each E microdomain contains one thin disklike crystal, randomly oriented . Thus, the sharp form factor minimum indicated by the dashed curve in Figure a is no longer present, and higher-order peaks are easily seen, such as the √3 and √4 peaks for E/VCH 5/22.…”

Polymer Crystallization Confined in One, Two, or Three Dimensions

“…TEM micrographs of E/VCH 10/26, a cylinder-forming polymer similar to E/VCH 6/25, have also been published previously; 16 they show ribbonlike crystals of E running along the cylinder axis. Here, we turn to the lamellar and gyroid cases.…”

“…In the case of the sphere-forming E/VCH 5/22 (Figure a), the q / q * = √3 peak expected for a bcc lattice is visible only as a weak shoulder, because the form factor for scattering from spheres of the appropriate diameter (dashed curve in Figure a) has a minimum in this vicinity . After E block crystallization, the electron density within the E domains is no longer uniform, nor is it precisely the same from one domain to the next; this can be seen directly in a published TEM image of E/VCH 5/22, which shows that each E microdomain contains one thin disklike crystal, randomly oriented . Thus, the sharp form factor minimum indicated by the dashed curve in Figure a is no longer present, and higher-order peaks are easily seen, such as the √3 and √4 peaks for E/VCH 5/22.…”

Synthesis and Characterization of ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Crystallization Behavior and Morphology

“…Whereas in the blend with a lamellar structure T c (PEO) = 30 °C, a large supercooling was necessary to induce PEO crystallization within PEO cylinders ( T c = −25 °C) or spheres ( T c = −35 °C). Similar results were obtained for other block copolymers, exhibiting confined crystallization within isolated spherical or cylindrical microdomains. ,, Confined crystallization within microdomains is often connected with a substantial decrease in crystallinity compared to the corresponding homopolymers due to spatial restrictions and nucleation problems. − ,− In contrast, for PE containing block copolymers the degree of crystallinity is independent of the type of microdomain and comparable with PE homopolymer, which might be attributed to the usually very thin PE crystals ( d ≈ 5 nm). , Crystallization can even be suppressed if the crystallizable block is confined into spheres or cylinders. , …”

Copolymers Prepared by Exchange Reactions Enhance the Properties of Miscible Polymer Blends

“…We also observed that extruded PCL, which is relatively crystalline, stains to a greater degree than extruded PU-1 , which is amorphous. This difference has been noted for staining semicrystalline polymers. , Therefore, the increased staining of the blends led us to further investigate if the copolymer imparts higher crystallinity to the homopolymer blends.…”

Polymer Crystallization Confined in One, Two, or Three Dimensions

“…TEM micrographs of E/VCH 10/26, a cylinder-forming polymer similar to E/VCH 6/25, have also been published previously; 16 they show ribbonlike crystals of E running along the cylinder axis. Here, we turn to the lamellar and gyroid cases.…”

“…In the case of the sphere-forming E/VCH 5/22 (Figure a), the q / q * = √3 peak expected for a bcc lattice is visible only as a weak shoulder, because the form factor for scattering from spheres of the appropriate diameter (dashed curve in Figure a) has a minimum in this vicinity . After E block crystallization, the electron density within the E domains is no longer uniform, nor is it precisely the same from one domain to the next; this can be seen directly in a published TEM image of E/VCH 5/22, which shows that each E microdomain contains one thin disklike crystal, randomly oriented . Thus, the sharp form factor minimum indicated by the dashed curve in Figure a is no longer present, and higher-order peaks are easily seen, such as the √3 and √4 peaks for E/VCH 5/22.…”

Synthesis and Characterization of ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Crystallization Behavior and Morphology

“…Whereas in the blend with a lamellar structure T c (PEO) = 30 °C, a large supercooling was necessary to induce PEO crystallization within PEO cylinders ( T c = −25 °C) or spheres ( T c = −35 °C). Similar results were obtained for other block copolymers, exhibiting confined crystallization within isolated spherical or cylindrical microdomains. ,, Confined crystallization within microdomains is often connected with a substantial decrease in crystallinity compared to the corresponding homopolymers due to spatial restrictions and nucleation problems. − ,− In contrast, for PE containing block copolymers the degree of crystallinity is independent of the type of microdomain and comparable with PE homopolymer, which might be attributed to the usually very thin PE crystals ( d ≈ 5 nm). , Crystallization can even be suppressed if the crystallizable block is confined into spheres or cylinders. , …”

Copolymers Prepared by Exchange Reactions Enhance the Properties of Miscible Polymer Blends

“…We also observed that extruded PCL, which is relatively crystalline, stains to a greater degree than extruded PU-1 , which is amorphous. This difference has been noted for staining semicrystalline polymers. , Therefore, the increased staining of the blends led us to further investigate if the copolymer imparts higher crystallinity to the homopolymer blends.…”

Polymer Crystallization Confined in One, Two, or Three Dimensions

“…TEM micrographs of E/VCH 10/26, a cylinder-forming polymer similar to E/VCH 6/25, have also been published previously; 16 they show ribbonlike crystals of E running along the cylinder axis. Here, we turn to the lamellar and gyroid cases.…”

“…In the case of the sphere-forming E/VCH 5/22 (Figure a), the q / q * = √3 peak expected for a bcc lattice is visible only as a weak shoulder, because the form factor for scattering from spheres of the appropriate diameter (dashed curve in Figure a) has a minimum in this vicinity . After E block crystallization, the electron density within the E domains is no longer uniform, nor is it precisely the same from one domain to the next; this can be seen directly in a published TEM image of E/VCH 5/22, which shows that each E microdomain contains one thin disklike crystal, randomly oriented . Thus, the sharp form factor minimum indicated by the dashed curve in Figure a is no longer present, and higher-order peaks are easily seen, such as the √3 and √4 peaks for E/VCH 5/22.…”

Synthesis and Characterization of ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Crystallization Behavior and Morphology

“…Whereas in the blend with a lamellar structure T c (PEO) = 30 °C, a large supercooling was necessary to induce PEO crystallization within PEO cylinders ( T c = −25 °C) or spheres ( T c = −35 °C). Similar results were obtained for other block copolymers, exhibiting confined crystallization within isolated spherical or cylindrical microdomains. ,, Confined crystallization within microdomains is often connected with a substantial decrease in crystallinity compared to the corresponding homopolymers due to spatial restrictions and nucleation problems. − ,− In contrast, for PE containing block copolymers the degree of crystallinity is independent of the type of microdomain and comparable with PE homopolymer, which might be attributed to the usually very thin PE crystals ( d ≈ 5 nm). , Crystallization can even be suppressed if the crystallizable block is confined into spheres or cylinders. , …”

Copolymers Prepared by Exchange Reactions Enhance the Properties of Miscible Polymer Blends

“…We also observed that extruded PCL, which is relatively crystalline, stains to a greater degree than extruded PU-1 , which is amorphous. This difference has been noted for staining semicrystalline polymers. , Therefore, the increased staining of the blends led us to further investigate if the copolymer imparts higher crystallinity to the homopolymer blends.…”