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Host-guest self-assembly in block copolymer blends.

Park WI, Kim Y, Jeong JW, Kim K, Yoo JK, Hur YH, Kim JM, Thomas EL, Alexander-Katz A, Jung YS - Sci Rep (2013)

Bottom Line: Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology.As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated.These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.

ABSTRACT
Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology. As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated. These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs.

No MeSH data available.


Related in: MedlinePlus

SEM and TEM images of the host-guest self-assembly nanostructures.(a) A lower-magnification SEM image of the optimized hierarchical morphology. (b) AFM image. (c) – (d) cross-sectional (c) and top-down (d, left) TEM images. EDS elemental mapping results for Fe (d, center) and O (d, right). (d, center) The elemental map is overlapped with a dark field TEM image.
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f3: SEM and TEM images of the host-guest self-assembly nanostructures.(a) A lower-magnification SEM image of the optimized hierarchical morphology. (b) AFM image. (c) – (d) cross-sectional (c) and top-down (d, left) TEM images. EDS elemental mapping results for Fe (d, center) and O (d, right). (d, center) The elemental map is overlapped with a dark field TEM image.

Mentions: We now demonstrate how mediation by mixed solvent vapors can lead to a new uniform microdomain pattern formed by the host-guest self-assembly of the nominally highly incompatible pair of BCPs. Figure 2b shows how the morphology depends on the volumetric mixture ratio of heptane and toluene (Vhep/Vtol) in the mixed solvent vapors, while the volume ratio of DS45 and SF35 BCPs was fixed at 2.5. With a small amount of heptane added to increase in the blend, the PDMS cylinders formed a partial network structure (Figure 2b, Vhep/Vtol = 0.33), similar to the mixed morphology of cylinders and perforated lamellae. The expansion of the PDMS block by heptane is supported by a gradual increase of the PDMS area fraction and a decrease of average area per PS perforation with increasing Vhep/Vtol, as shown in Figure 4b. When Vhep/Vtol ~ 0.5, the PDMS network structures became more connected and continuous, and multiple PFS dots were isolated as a group inside the network. Further increase of the heptane fraction resulted in more circular and regular perforations with reduced average diameters, although the variation in the shape and size of the perforations resulted in a variation in the number of PFS spheres per pore.


Host-guest self-assembly in block copolymer blends.

Park WI, Kim Y, Jeong JW, Kim K, Yoo JK, Hur YH, Kim JM, Thomas EL, Alexander-Katz A, Jung YS - Sci Rep (2013)

SEM and TEM images of the host-guest self-assembly nanostructures.(a) A lower-magnification SEM image of the optimized hierarchical morphology. (b) AFM image. (c) – (d) cross-sectional (c) and top-down (d, left) TEM images. EDS elemental mapping results for Fe (d, center) and O (d, right). (d, center) The elemental map is overlapped with a dark field TEM image.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824169&req=5

f3: SEM and TEM images of the host-guest self-assembly nanostructures.(a) A lower-magnification SEM image of the optimized hierarchical morphology. (b) AFM image. (c) – (d) cross-sectional (c) and top-down (d, left) TEM images. EDS elemental mapping results for Fe (d, center) and O (d, right). (d, center) The elemental map is overlapped with a dark field TEM image.
Mentions: We now demonstrate how mediation by mixed solvent vapors can lead to a new uniform microdomain pattern formed by the host-guest self-assembly of the nominally highly incompatible pair of BCPs. Figure 2b shows how the morphology depends on the volumetric mixture ratio of heptane and toluene (Vhep/Vtol) in the mixed solvent vapors, while the volume ratio of DS45 and SF35 BCPs was fixed at 2.5. With a small amount of heptane added to increase in the blend, the PDMS cylinders formed a partial network structure (Figure 2b, Vhep/Vtol = 0.33), similar to the mixed morphology of cylinders and perforated lamellae. The expansion of the PDMS block by heptane is supported by a gradual increase of the PDMS area fraction and a decrease of average area per PS perforation with increasing Vhep/Vtol, as shown in Figure 4b. When Vhep/Vtol ~ 0.5, the PDMS network structures became more connected and continuous, and multiple PFS dots were isolated as a group inside the network. Further increase of the heptane fraction resulted in more circular and regular perforations with reduced average diameters, although the variation in the shape and size of the perforations resulted in a variation in the number of PFS spheres per pore.

Bottom Line: Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology.As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated.These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.

ABSTRACT
Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology. As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated. These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs.

No MeSH data available.


Related in: MedlinePlus