Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session B4: Self-assembled Macromolecular Structures |
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Sponsoring Units: DPOLY Chair: Spiros Anastasiadis, Foundation for Research and Technology, Hellas, Keraklion, Greece Room: Morial Convention Center 206 |
Monday, March 10, 2008 11:15AM - 11:51AM |
B4.00001: Stimuli Responsive Vesicles, Micelles and Rods from Polypeptide-based Block Copolymers Invited Speaker: The self-assembly of amphiphilic block copolymers is dictated primarily by the balance between the hydrophobic core volume and the hydrophilic corona. In these studies, amphiphilic block copolymers containing poly(lysine) (P(Lys)) blocks were synthesized and their solution properties studied using dynamic light scattering, circular dichroism spectroscopy and transmission electron microscopy. The hydrophobic block used was either poly(butadiene) or a statistical copolymer of propylene oxide and ethylene oxide. The latter polymer exhibits a tunable critical point, below which the block copolymer is in the ``double hydrophilic'' limit. In these multiply-responsive materials, we exploit secondary structure changes that occur within the P(Lys) chain to observe changes in solution morphology as a function of solution conditions. At high pH, the P(Lys) chain assumes either an $\alpha$-helical or $\beta$-sheet conformation depending on temperature, while at lower pH the side chains become protonated, resulting in an expanded coil configuration. The effect of morphology changes due to these structural transitions will be discussed in the context of the interfacial curvature changes with pH and temperature. These dynamic materials have potential applications as viscosity modifiers, liquid crystals and gels. [Preview Abstract] |
Monday, March 10, 2008 11:51AM - 12:27PM |
B4.00002: Templated Self Assembly of Block Copolymer Thin Films Invited Speaker: A primary limitation of block copolymer films as templates for next generation electronic or data storage devices is the prohibitively long times required for thermally driven self-assembly and defect annihilation and long range order development. We demonstrate a high-throughput approach involving temporal zone (cold-hot-cold) annealing of block copolymer films well below their order-disorder transition temperature (T: HOT $<<$ T: ODT) that produces low defect concentrations, large grain size and a preferential alignment of the block microphase relatively rapidly. Promising results have been obtained by combining zone annealing with directed assembly on topographically patterned substrates. This combination results in the rapid development of long-range order which persists over the entire patterned area. The evolution of order in these templates is quantified using neutron reflection in conjunction with tomographic small angle scattering, and compared to scattering from model simulations to obtain a 3-D description of ordering within channel templates. The ability to rapidly achieve quantifiable long-range order in block copolymers (with inaccessible order-disorder transition temperatures) using non-destructive methods within templates suggests zone annealing as a robust nanomanufacturing method for guided self-assembly. [Preview Abstract] |
Monday, March 10, 2008 12:27PM - 1:03PM |
B4.00003: Single Molecules and Surface Induced Nanopattern in Ultrathin Blockcopolymer Films - Scanning Force Microscopy Invited Speaker: Supramolecular self-organization is a powerful tool for producing nanostructured patterns as an alternative to lithographic techniques. Block copolymers from incompatible fragments are well known for their ability to self-assemble into well-ordered periodic structures at a length scale of 10 – 100 nm. Besides length, composition, and the type and number of the constituent blocks, branching and chemical transformation provides a further parameter for controlling the molecular conformation and structure. In this work we describe a new approach to prepare polymeric supramolecular complexes using wedge-shaped amphiphilic molecules, which are able to self-assemble into cylindrical supramolecular structures. Scanning force microscopy on single macromolecules is demonstrated to provide a powerful tool to characterize the supramolecular complexes and structure formation in ultrathin films. The self-assembly properties of their complexes with homopolymers as well as block copolymers will be discussed. [Preview Abstract] |
Monday, March 10, 2008 1:03PM - 1:39PM |
B4.00004: Using block copolymer assembly to tailor surface properties. Invited Speaker: A challenge in the design of surfaces is to be able to control molecular function with nm-scale precision. This presentation discusses the use of block copolymers to deliver chemical functions to the near-surface region with precise control of surface functionality. Block copolymers prepared using either anionic or ATRP polymerization were used followed by subsequent functional group modification. By using block copolymers alone and in combination, it is possible to tailor not only surface properties, but thei mechanical behavior of the polymer surface region. The effect of surface composition and patterning on the biological response to self-organized surfaces will be discussed in the context of well characterized surfaces. [Preview Abstract] |
Monday, March 10, 2008 1:39PM - 2:15PM |
B4.00005: Integration of block copolymers into lithographic processes Invited Speaker: In the photolithographic process, information in the form of exposed and unexposed material is transferred to a sacrificial photoresist film in the exposure tool. Through a series of processing steps patterned features are ultimately created from that information that can then define components of devices or other functional materials. As feature dimensions shrink below 30 nm, however, the fidelity of the transferred information using current resists may not meet manufacturing requirements, particularly with respect to control over the precise size and shape of the patterned features, and the cost of manufacturing at ever higher resolution may become prohibitively expensive. We are investigating techniques to integrate self-assembling block copolymers into the lithographic process for improved information transfer, process control, and sub 15 nm resolution. We demonstrate strategies to reach these objectives and at the same time retain essential lithographic process attributes such as pattern perfection, registration, the ability to pattern non-regular device-oriented structures, and high volume manufacturing. [Preview Abstract] |
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