Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session X5: The Corporate Feel: Atomic Force Microscopy in Industry |
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Sponsoring Units: FIAP Chair: Jason Cleveland, Asylum Research Room: Ballroom C1 |
Thursday, March 24, 2011 2:30PM - 3:06PM |
X5.00001: Accelerated design and quality control of impact modifiers for plastics through atomic force microscopy (AFM) analysis Invited Speaker: Standard polymer resins are often too brittle or do not meet other mechanical property requirements for typical polymer applications. To achieve desired properties it is common to disperse so called ``impact modifiers'', which are spherical latex particles with diameters of much less than one micrometer, into the pure resin. Understanding and control of the entire process from latex particle formation to subsequent dispersion into polymer resins are necessary to accelerate the development of new materials that meet specific application requirements. In this work AFM imaging and nanoindentation techniques in combination with AFM-based spectroscopic techniques were applied to assess latex formation and dispersion. The size and size distribution of the latex particles can be measured based on AFM amplitude modulation images. AFM phase images provide information about the chemical homogeneity of individual particles. Nanoindentation may be used to estimate their elastic and viscoelastic properties. Proprietary creep and nanoscale Dynamic Mechanical Analysis (DMA) tests that we have developed were used to measure these mechanical properties. The small size of dispersed latex inclusions requires local mechanical and spectroscopic analysis techniques with high lateral and spatial resolution. We applied the CRAVE AFM method, developed at NIST, to perform mechanical analysis of individual latex inclusions and compared results with those obtained using nanoscale DMA. NanoIR, developed by Anasys Inc., and principal component confocal Raman were used for spectroscopic analysis and results from both techniques compared. [Preview Abstract] |
Thursday, March 24, 2011 3:06PM - 3:42PM |
X5.00002: Scanning Probe Evaluation of Electronic, Mechanical and Structural Material Properties Invited Speaker: We present atomic force microscopy (AFM) studies of a range of properties from three different classes of materials: mixed ionic electronic conductors, low-k dielectrics, and polymer-coated magnetic nanoparticles. (1) Mixed ionic electronic conductors are being investigated as novel diodes to drive phase-change memory elements. Their current-voltage characteristics are measured with direct-current and pulsed-mode conductive AFM (C-AFM). The challenges to reliability of the C-AFM method include the electrical integrity of the probe, the sample and the contacts, and the minimization of path capacitance. The role of C-AFM in the optimization of these electro-active materials will be presented. (2) Low dielectric constant (low-k) materials are used in microprocessors as interlayer insulators, a role directly affected by their mechanical performance. The mechanical properties of nanoporous silicate low-k thin films are investigated in a comparative study of nanomechanics measured by AFM and by traditional nanoindentation. Both methods are still undergoing refinement as reliable analytical tools for determining nanomechanical properties. We will focus on AFM, the faster of the two methods, and its developmental challenges of probe shape, cantilever force constant, machine compliance and calibration standards. (3) Magnetic nanoparticles are being explored for their use in patterned media for magnetic storage. Current methods for visualizing the core-shell structure of polymer-coated magnetic nanoparticles include dye-staining the polymer shell to provide contrast in transmission electron microscopy. AFM-based fast force-volume measurements provide direct visualization of the hard metal oxide core within the soft polymer shell based on structural property differences. In particular, the monitoring of adhesion and deformation between the AFM tip and the nanoparticle, particle-by-particle, provides a reliable qualitative tool to visualize core-shell contrast without the use of additional contrast enhancing agents. [Preview Abstract] |
Thursday, March 24, 2011 3:42PM - 4:18PM |
X5.00003: Nanomechanical characterization of polypropylene-based materials with multifrequency atomic force microscopy (AFM)-based methods Invited Speaker: Atomic force microscopy (AFM) is a powerful technique with broad applications to characterization of surfaces, primarily used for nanoscale quantitative topographic measurements and qualitatively distinguishing between material properties on the surface. We describe recent advances in our capabilities to quantify nanoscale mechanical measurements of surface properties using recently developed high frequency and multifrequency methods. Initial focus of this work is for polymeric materials (and specifically polypropylene based blends), where nanomechanical characterization is critical for effective understanding of structure-property relationships, especially for more complicated multi-component materials such as blends and composites. SPM techniques rely on complicated tip-sample interactions that must be effectively separated and understood if we are to ultimately identify and quantify specific materials and material properties at the nanoscale. We describe different approaches to this problem utilizing a number of AFM based techniques including force curves, bimodal imaging and contact resonance imaging. Ultimately, these techniques yield quantitative maps of conservative and dissipative tip-sample interactions that are then converted into elastic and viscous moduli maps. We describe initial applications of these methods to measure mechanical properties such as storage and loss moduli of model polypropylene containing blends including polypropylene/rubber and polypropylene/polystyrene blends. Finally, quantitative moduli values obtained by methods described above are compared to those obtained by bulk methods. [Preview Abstract] |
Thursday, March 24, 2011 4:18PM - 4:54PM |
X5.00004: Probing Photovoltaic Performance Invited Speaker: A wide range of nanostructured materials including organic bulk heterojunction blends, solution processed colloidal semiconductors, and hybrid organic/inorganic thin films are being explored for solar energy applications. These sytems typically exhibit nanoscale heterogenity in their electronic and optical properties. Scanning probes are critical for building a microscopic picture of the performance of new nanostructured and thin film photovoltaic materials--and may ultimately prove to be a valuable metrology tool for process control during production--because scanning probe microscopy provides a unique opportunity to correlate local charge generation, recombination and transport with local structure in these systems. In this talk I will focus on techniques developed and lessons learned during our group's study of thin film solar cell materials with a particular emphasis on nanostructured organic bulk heterojunction blends. [Preview Abstract] |
Thursday, March 24, 2011 4:54PM - 5:30PM |
X5.00005: Challenges and opportunities for probe-based information technology Invited Speaker: Scanning probe microscopes have become standard tools for characterization of materials and devices at the nanoscale. But what about ``OEM'' versions for information technology? The standard answer is that probe-based lithography or storage is not practical because it cannot scale-their cost and complexity will never allow useful devices to be made with probes. Such was not always the conventional wisdom in the industrial community. The Millipede Project,\footnote{http://www.zurich.ibm.com/st/storage/concept.html} pioneered by Gerd Binnig at IBM and pursued at other companies such as Hitachi and Seagate, sought to scale the number of probes to $\sim$1000. In fact, they were successful, but not enough to be competitive with FLASH memory. Since then, order of magnitude improvements have been made both in scaling up to the number of probes past ten million,\footnote{F. Huo et al, Science ${\bf 321}$, 1658 (2008).} and in scaling down the minimum bit size below two nanometers.\footnote{C. Cen et al, Science, ${\bf 323}$, 1026 (2009).} Combining these two approaches may well justify the statement: ``There's plenty of room for probes at the bottom.'' [Preview Abstract] |
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