Limits...
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

SCFT simulation.(a) Cross-section TEM image of the host-gest assembled BCP blend. (b) Unit cell structure for the SCFT calculation, which is consistent with the TEM image. (c) Calculated free energy of the PDMS-b-PS HPL morphology depending on the position and size of the guest PS-b-PFS nano-sphere incorporated in the PS perforation. For the particle radius of 0.2 – 0. 22 L0, the minimization of free energy is achieved by the location of nano-sphere at the center. (d) The illustration of periodic configurations achieving the minimum free energy.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3824169&req=5

f6: SCFT simulation.(a) Cross-section TEM image of the host-gest assembled BCP blend. (b) Unit cell structure for the SCFT calculation, which is consistent with the TEM image. (c) Calculated free energy of the PDMS-b-PS HPL morphology depending on the position and size of the guest PS-b-PFS nano-sphere incorporated in the PS perforation. For the particle radius of 0.2 – 0. 22 L0, the minimization of free energy is achieved by the location of nano-sphere at the center. (d) The illustration of periodic configurations achieving the minimum free energy.

Mentions: SCFT simulations were utilized to investigate the spontaneous formation of the hybrid nanostructure. We designed our host-guest system by performing simulations of a HPL phase (PDMS-b-PS) and a nano-sphere with a PS shell, which effectively mimics the spherical nature of the PS-b-PFS corona. The unit cell of the hierarchically assembled structure obtained by the simulations was consistent with the cross-sectional TEM image of the sample before plasma oxidation, as seen in Figures 6a and 6b. Previous hybrid-SCFT simulations, employed to study the effects of complex geometries on BCP systems containing defects and nano-spheres [Kim, Y., Chen, H. & Alexander-Katz, A. Unpublished data], revealed that the system is stabilized when a nano-sphere is positioned at a defect center by minimizing the chain stretching of the host BCP. Figure 6c shows the free energy of the perforated lamellar phase of the PDMS-b-PS BCP as a function of the nano-sphere size and the position along the z-axis. For smaller nano-spheres (radius < 0.2 L0), the free energy minimization is achieved when the spheres are located at the junctions (Z ~ ± 0.2 L0) of the PS-lamellar plane and PS-perforation. However, when the radii of the nano-spheres are increased above 0.2 L0, the nano-spheres eventually stabilize the system at the center of the PS-perforations (Z = 0) because larger nano-spheres can reduce PS chain stretching simultaneously at the upper and lower junctions, resulting in the minimum free energy at Z = 0, as shown in Figure 6c. The estimated radius of the PS-b-PFS nano-sphere of the SF35 BCP in the experiment is 0.216 L0 (~17.7 nm), which is consistent with the size that stabilizes the BCP blend system at Z = 0 in the SCFT calculation.


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)

SCFT simulation.(a) Cross-section TEM image of the host-gest assembled BCP blend. (b) Unit cell structure for the SCFT calculation, which is consistent with the TEM image. (c) Calculated free energy of the PDMS-b-PS HPL morphology depending on the position and size of the guest PS-b-PFS nano-sphere incorporated in the PS perforation. For the particle radius of 0.2 – 0. 22 L0, the minimization of free energy is achieved by the location of nano-sphere at the center. (d) The illustration of periodic configurations achieving the minimum free energy.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: SCFT simulation.(a) Cross-section TEM image of the host-gest assembled BCP blend. (b) Unit cell structure for the SCFT calculation, which is consistent with the TEM image. (c) Calculated free energy of the PDMS-b-PS HPL morphology depending on the position and size of the guest PS-b-PFS nano-sphere incorporated in the PS perforation. For the particle radius of 0.2 – 0. 22 L0, the minimization of free energy is achieved by the location of nano-sphere at the center. (d) The illustration of periodic configurations achieving the minimum free energy.
Mentions: SCFT simulations were utilized to investigate the spontaneous formation of the hybrid nanostructure. We designed our host-guest system by performing simulations of a HPL phase (PDMS-b-PS) and a nano-sphere with a PS shell, which effectively mimics the spherical nature of the PS-b-PFS corona. The unit cell of the hierarchically assembled structure obtained by the simulations was consistent with the cross-sectional TEM image of the sample before plasma oxidation, as seen in Figures 6a and 6b. Previous hybrid-SCFT simulations, employed to study the effects of complex geometries on BCP systems containing defects and nano-spheres [Kim, Y., Chen, H. & Alexander-Katz, A. Unpublished data], revealed that the system is stabilized when a nano-sphere is positioned at a defect center by minimizing the chain stretching of the host BCP. Figure 6c shows the free energy of the perforated lamellar phase of the PDMS-b-PS BCP as a function of the nano-sphere size and the position along the z-axis. For smaller nano-spheres (radius < 0.2 L0), the free energy minimization is achieved when the spheres are located at the junctions (Z ~ ± 0.2 L0) of the PS-lamellar plane and PS-perforation. However, when the radii of the nano-spheres are increased above 0.2 L0, the nano-spheres eventually stabilize the system at the center of the PS-perforations (Z = 0) because larger nano-spheres can reduce PS chain stretching simultaneously at the upper and lower junctions, resulting in the minimum free energy at Z = 0, as shown in Figure 6c. The estimated radius of the PS-b-PFS nano-sphere of the SF35 BCP in the experiment is 0.216 L0 (~17.7 nm), which is consistent with the size that stabilizes the BCP blend system at Z = 0 in the SCFT calculation.

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