Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session L22: Confinement-Induced Structures in Block Copolymers |
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Eric Cochran, Iowa State University Room: Morial Convention Center 214 |
Tuesday, March 11, 2008 2:30PM - 3:06PM |
L22.00001: Dillon Symposium Break
|
Tuesday, March 11, 2008 3:06PM - 3:18PM |
L22.00002: Block copolymers in cylindrical confinement: role of thermal fluctuations and confinement parameters in structure formation Kirill Titievsky Phase segregated block copolymer morphology and dimensions were studied using explicit simulations of interacting bead-spring chains at physically realistic densities. In particular, The distribution of characteristic morphologies and structure dimensions for a given fiber diameter are characterized. Key novel aspects of this work inlude sampling of thermal fluctuations in full three dimension, rather than finding minimum energy surfaces and extensive comparison to experimental data on electrospun block copolymer--polymer fibers. Two methodological innovations are also introduced. First, an unprecedentedly precise estimate of Flory $\chi$ parameters for the model allows a quantitative comparison to field theoretic models. Second, a novel reflective boundary model allows common boundary artifacts in total density to be effectively eliminated, even for fibers with of dimensions comparable to single chains. [Preview Abstract] |
Tuesday, March 11, 2008 3:18PM - 3:30PM |
L22.00003: Complex Morphologies of Symmetric Diblock Copolymers under Nano-Confinement Dong Meng, Yuhua Yin, Jacqueline Acres, Qiang Wang We have performed parallel self-consistent field (SCF) calculations in continuum to study the self-assembled morphologies of symmetric diblock copolymers under planner and cylindrical confinement by homogeneous surface(s). The SCF equations are solved with high accuracy in real space, without \textit{a priori} knowledge of the possible morphologies. Effects of surface preference and film thickness / pore diameter are investigated in detail. In addition to simple morphologies (i.e., surface parallel and perpendicular lamellae), complex morphologies are found in both cases and their stable regions are determined. Our SCF calculations also reveal the formation mechanism of these complex morphologies. [Preview Abstract] |
Tuesday, March 11, 2008 3:30PM - 3:42PM |
L22.00004: Nano-structures of block copolymers under confinement Jie Feng, Eli Ruckenstein By employing a bond fluctuation lattice Monte Carlo simulation, block copolymers confined in nano-cylindrical cavities are studied. The effects of preference of the surface for segments and incompatibility between different blocks as well as the symmetry of the chains and the ratio of cavity diameters to the lamellae period of copolymers in the bulk $\left( {D/L_0 } \right)$ are investigated in detail. Numerous novel morphologies such as complicated helical structures, plate morphologies with fins and dendrites etc are presented in this work. Some phase diagrams regarding above parameters are provided in order to understand the transitions between structures. Additionally, the orientation parameters indicating the alignments of the polymer chains were calculated and correlated with the morphologies. The simulation results are compared with experimental results qualitatively. [Preview Abstract] |
Tuesday, March 11, 2008 3:42PM - 3:54PM |
L22.00005: Morphologies of a diblock copolymer melt confined in a spherical nanopore Bing Miao, Janine Tulkens, Robert Wickham We systematically investigate the microdomain morphologies that self-assemble in a diblock copolymer melt confined in a spherical nanopore, using real-space self-consistent mean-field theory. Near the surface of the nanopore we find that perforated-layer structures form, with four-, five-, and six- fold coordinated pores, for melts that form the cylindrical phase in the bulk. Simultaneously, spherical domains, toroidal domains, or small networks form in the centre of the pore. We vary the diameter of the pore and accurately locate the diameters where phase transitions between these morphologies occur. The effect of confinement on melts that form spherical microdomains in the bulk is also examined. We find that convergence to regular structures is complicated by the formation of defects, and we develop techniques to eliminate these defects. Methods to distinguish the various morphologies will also be discussed. [Preview Abstract] |
Tuesday, March 11, 2008 3:54PM - 4:06PM |
L22.00006: Spherical nano-shells of block copolymers Marco Pinna, Andrei Zvelindovsky Using cell dynamics simulation we investigate morphologies block copolymers confined in a spherical shell. The shell is formed by coating of a colloidal particle with a block copolymer thin film. We examine the influence of molecular composition, thickness of the film, curvature of the shell on the nano- structure of the shell. Several block copolymer morphologies are investigated: bulk lamellae, cylinders, spheres and bicontinuous. Deviation from the bulk structure develops under influence of confinement between curved surfaces. The curvature influences the defect density in the formed structure. [Preview Abstract] |
Tuesday, March 11, 2008 4:06PM - 4:18PM |
L22.00007: Water permeable nanotubes from amphiphilic block copolymers Jiun-Tai Chen, Mingfu Zhang, Ling Yang, Margaret Collins, Jim Parks, Armando Avallone, Thomas Russell We used anodic aluminum oxide (AAO) membranes to generate nanotubes of the cylinder-forming polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymer. The PS-b-PEO solution was introduced into the cylindrical nanopores of an AAO membrane by capillary force and polymeric nanotubes formed after solvent evaporation. Owing to the water solubility of the cylindrical PEO microdomains and the orientation of the cylindrical PEO microdomains with respsect to the nanotube walls, the nanotubes were permeable to aqueous media. We also prepared PS-b-PEO nanotubes inside amorphous carbon nanotubes (a-CNTs) where the microphase separated morphology could serve as a template for functionalizing the interior of the carbon nanotubes. [Preview Abstract] |
Tuesday, March 11, 2008 4:18PM - 4:30PM |
L22.00008: Effect of curvature on equilibrium and non-equilibrium properties of a 2D smectic phase. Leopoldo R. Gomez, Enrique M. Valles, Daniel A. Vega We study through the Otha-Kawasaki model for diblock copolymers equilibrium and non-equilibrium features of two dimensional smectic phases on curved sinusoidal substrates. At low curvatures defect free patters are found to be stable. In agreement with theoretical predictions of Vitelli and Nelson [], at high curvatures topological defects are observed in the ground state. In this regime positive (negative) disclinations are located in regions of positive (negative) curvature. The configurations formed by stripes aligned with the lines of longitude are found to be unstable, while the equilibrium state is formed by the stripes aligned with the parallels. General features of smectic phases on curved backgrounds are discussed by a Frank elastic free energy in the one constant approximation. [Preview Abstract] |
Tuesday, March 11, 2008 4:30PM - 4:42PM |
L22.00009: Phase Transitions in block copolymers under external electric field and in confinements Andrei Zvelindovsky Phase transitions induced by external factors in various block copolymer systems are investigated by means of coarse-grained computer simulations. We develop several meso-scale computational techniques: dynamic self-consistent field theory and cell dynamics simulation. This contribution puts focus on dynamics of systems subjected to two examples of external fields. First, we describe dynamics of phase transitions of various block copolymer morphologies (lamellae, hexagonally packed cylinders, spheres, gyroid, hexagonally perforated lamellae) under an applied electric field. Second example illustrates kinetics of surface phase transitions in confined systems (thin films). [Preview Abstract] |
Tuesday, March 11, 2008 4:42PM - 4:54PM |
L22.00010: Fluctuation-Induced Line-Edge Roughness in Nano-Confined Block Copolymer Thin Films August Bosse, Ronald Jones, Alamgir Karim Block copolymer (BCP) thin film systems are currently under intense scrutiny as a potential nano-scale fabrication mask for pattering next-generation semi-conductors and magnetic media on the $5$ to $20$ nm scale. However, there are certain fundamental issues that need to be resolved, or at least well understood, if BCP systems are going to evolve into a feasible fabrication tool, most notable of which is the scale and system-parameter-dependence of microdomain--matrix-interface line-edge roughness (LER). We present a computational study of microdomain--matrix-interface LER for a nano-confined $AB$ diblock copolymer thin film. The BCP system was simulated using a field-theoretic sampling technique based on a ``hybrid'' mean-field--Monte Carlo framework. We present a summary of our simulation technique, and we examine the dependence of LER on the Flory $\chi$ parameter and the copolymer molecular weight. [Preview Abstract] |
Tuesday, March 11, 2008 4:54PM - 5:06PM |
L22.00011: The Hierarchical Morphology of Dielectric Mirrors Michael Birnkrant, Christopher Li, Lalgudi Natarajan, Vincent Tondiglia, Pamela Lloyd, Richard Sutherland, Timothy Bunning Active hierarchically structured volume reflection gratings can be fabricated by combining top-down and bottom-up nanomanufacturing techniques. In a typical process holographic photopolymerization (HP) formed lamellar structures of $\sim $200 nm in thickness confining a block copolymer (BCP) to $\sim $100 nm domains. The BCP self assembles into a variety of ordered structures with a period of $\sim $20 nm. A lamellar-in-lamellar structure was achieved and by varying the BCP structure more complex cylinder-in-lamellar and sphere-in-lamellar structures are envisioned. The HP and BCP phase separation/crystallization dichotomy during the formation of hierarchical dielectric mirrors will be discussed. [Preview Abstract] |
Tuesday, March 11, 2008 5:06PM - 5:18PM |
L22.00012: Crystalline - Crystalline Diblock Copolymers of Linear Polyethylene - Hydrogenated Polynorbornene Richard Register, Sasha Myers, Sheng Li The melt and solid-state morphologies of linear polyethylene (LPE) - hydrogenated polybnorbornene (hPN) diblock copolymers, and their crystallization behavior, were explored over a range of block ratios and diblock molecular weights. LPE and hPN are both highly-crystalline polymers, with similar melting points, so the final structure can potentially be dictated by the melt structure, or by crystallization of either block. For diblocks with molecular weights of 50 kg/mol, symmetric copolymers exhibited lamellar microphase-separated melts, while diblocks with 20 or 80{\%} LPE were homogeneous, indicating a modest LPE-hPN interaction energy density of approximately 1 J/cc. For the relatively slow crystallizations which can be conducted isothermally, hPN appears to always crystallize first; the two crystallization processes can be resolved by time-resolved DSC and x-ray diffraction at small undercoolings. However, the LPE block has a stronger temperature dependence of its crystallization rate, implying that LPE would crystallize first at deep undercoolings. Up to the highest diblock molecular weights explored (100 kg/mol), crystallization ``breaks out'' from the melt mesophase to form spherulites defined by the hPN block; subsequent crystallization of the LPE within these spherulites is apparent from a change in optical texture. [Preview Abstract] |
Tuesday, March 11, 2008 5:18PM - 5:30PM |
L22.00013: Deformation-induced structure changes in olefin block copolymer Feng Zuo, Yimin Mao, JongKahk Keum, Christian Burger, Benjamin Hsiao, Hongyu Chen, Debbie Chiu, Shih-Yaw Lai Uniaxial tensile deformation was applied on two olefin block copolymer (OBC) samples to investigate the structure, morphology and orientation development using in-situ small-angle X-ray scattering and wide-angle X-ray diffraction techniques. Two samples have similar molecular characteristics but different chain architectures due to the different content of chain shuttling agent in production. The samples behave alike at room temperature, but the difference becomes distinct at high temperatures, such as fracture strain and crystal orientation. As more chain shuttling agents was used, the more frequently the growing chains transferred between catalysts; shorter block segments are produced. The block length has a strong effect on the crystallization kinetics, resulting microstructures (lamellae versus fringe-micelle) and deformation-induced structure changes. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700