Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / Includes bibliographical references (leaves 59-61). / by Lynn Louise Chalfoun. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008. / Includes bibliographical references. / The development of nanoscale polymeric materials for mechanical applications necessitates advances in small-volume experimental techniques and analyses that reflect the viscoelastoplastic behavior of such materials. In this thesis, the time-dependence and response of homogeneous engineering polymers under confined contact loading are characterized as a function of polymer physical and structural properties. The validity of the time-independent metric indentation hardness Hi is evaluated through the combination of nanoindentation and atomic force microscopy imaging. In addition, the classic, time-dependent metric creep compliance J(t) is used to establish the experimental conditions necessary for linear elastic behavior for a set of thermoplastic and thermoset materials. For large indentations (hmax > 1 um), properties are tacitly assumed to reflect the properties of bulk polymer; however, this assumption does not hold within 100 nm of a free surface or interface of amorphous polymers such as polystyrene and polycarbonate. The contact deformation mechanism near an amorphous polymer surface is found to scale with the surface area of contact, suggesting the dynamic formation of a structural interphase region. Chemical probe functionalization experiments are developed to explore the effects of probe surface charge on the probe-polymer interface and contribute to the understanding of the interphase that dominates nanocomposite material response. A technique to rapidly screen mechanical response of combinatorial polymer libraries is presented, to establish structure-property-processing relationships of such chemomechanically defined interfaces before nanoscale deformation mechanisms in confined polymers are fully understood. / (cont.) Finally, material design for elastic, viscoelastic, and viscoelastoplastic mechanical properties is discussed in terms of polymer physical length and time scales. / by Catherine Anne Tweedie. / Ph.D.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008. / Includes bibliographical references (leaf 54). / Twenty - first opportunities for Gigascale Integration will be governed in part by a hierarchy of physical limits on interconnect. Microprocessor performance is now limited by the poor delay and bandwidth performance of the on - chip global wiring layer. This thesis is envisioned as a critical showstopper of electronic industry in the near future. The physical reason behind the interconnect bottleneck is the resistive nature of metals. The introduction of copper in place of aluminum has temporarily improved the interconnect performance, but a more disruptive solution will be required in order to keep the current pace of progress, optical interconnect is an intriguing alternative to metallic wires. Many - core microprocessors will push performance per chip from the 10 gigaflop to the 10 teraflop range in the coming decade. Pin limitations, the energy cost of electrical signaling, and the non - scalability of chip - length global wires are significant bandwidth impediments. Silicon nanophotonic based many core architecture are introduced in order to meet the bandwidth requirements at acceptable power levels. / by Zhoujia Xu. / M.Eng.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 147-157). / The long-term goal of my Ph.D. study has been controlling the self-assembly of various materials using state-of-the-art nanofabrication techniques. Electron-beam lithography has been used for decades to generate nanoscale patterns, but its throughput is not high enough for fabricating sub-10-nm patterns over a large area. Templated block copolymer(BCP) self assembly is attractive for fabricating few-nanometer-scale structures at high throughput. On an unpattermed substrate, block copolymer self-assembly generates dense arrays of lines or dots without long-range order. Fortunately, physical features defined by electron lithography can guide the self-assembly of block copolymer. In our previous work, the orientation of cylindrical phase block copolymer was controlled simply by changing the distance between physical features, and resulting polymer patterns were analyzed by an image analysis program. Here, we first demonstrated high throughput sub-10-nm feature sizes by applying the same approach to a cylindrical morphology 16kg/mol PS-PDMS block copolymer. The half-pitch of the PDMS cylinders of this block copolymer film is 9 nm, so sub-10-nm structures can be fabricated. We also applied the similar approach to a triblock terpolymer to achieve dot patterns with square symmetry. To achieve a more complex pattern, electron-beam induced cross-linking of a block copolymer and second solvent-annealing process was used. By using this method, a line-dot hybrid pattern was achieved. Despite that the block copolymer self-assembly area had been heavily studied, researchers had yet to ascertain how to design nanostructures to achieve a desired target pattern using block copolymers. To address this problem, we developed a modular method that greatly simplifies the nanostructure design, and using this method, we achieved a circuit-like block-copolymer pattern over a large area. The key innovation is the use of a binary set of tiles that can be used to very simply cover the desired patterning area. Despite the simplicity of the approach, by exploiting neighbor-neighbor interactions of the tiles, a complex final pattern can be formed. The vision is thus one of programmability of patterning by using a simple instruction set. This development will thus be of interest to scientists and engineers across many fields involving self-assembly, including biomolecule, quantum-dot or nanowire positioning; algorithmic self-assembly; and integrated-circuit development. We applied this concept - controlling the assembly of materials using nanostructures - to a different material, protein. Single-molecule protein arrays are useful tools for studying biological phenomena at the single-molecule level, but have been developed only for a few specific proteins using the streptavidin-biotin complex as a linker. By using carefully designed gold nanopatterns and cysteine-gold interaction, we developed a process to make single-molecule protein arrays that can be used for patterning a broad range of proteins. / by Jae-Byum Chang. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994. / Includes bibliographical references (leaves 174-180). / by Ambuj D. Sagar. / Ph.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 78-80. / by Adebisi Oladimeji Oladipupo. / Sc.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, June 2005. / Includes bibliographical references (p. 38-39). / In this thesis, the chemical/mechanical properties and biocompatibility of gelatin were investigated to produce a gelatin scaffold for the release of bone morphogenetic proteins (BMPs) from composite particles. This delivery system, designed to regenerate bone, holds much promise as an alternative to bone grafts. The chemical properties of gelatin were examined through zeta potential measurements, swelling studies, optical microscopy, environmental scanning electron microscopy (ESEM), and collagenase degradation. Compressive tests and mercury porosimetry were performed to study the mechanical and structural properties of the scaffold. The biocompatibility of the scaffold was determined through cell optical imaging and DNA quantification studies. Based on findings of this research, the material choices were made and the synthesis method for the gelatin scaffold was developed. Gelatin A, 300B, derived from bovine collagen, with an isoelectric point of [approx.] 9, was selected. Crosslinking was accomplished by reacting 10 w/v% glutaraldehyde with 10 w/v% gelatin solution. The most effective crosslinking condition was found to be 5 hours at room temperature. Glycine rinses were conducted to cap any non- reacted (toxic) aldehyde groups, and the necessary length of time was found to be at least 48 hours at 37⁰C. Finally, based on pore size distribution and mechanical stability, an optimal lyophilization method was developed with initial freezing at -20⁰C for 1 day, followed by lyophilization of the scaffold for 1-2 days. In terms of mechanical properties of the gelatin and amount of protein delivered, the most effective loading of poly(lactic-co-glycolic acid)/apatite/protein composite particles was found to be 10% of the mass of the gelatin. / by Elizabeth A. Hager. / S.B.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / by Andrew Gouldstone. / B.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987. / Vita. / Bibliography: v. 2, leaves 324-359. / by Steven Anthony Gedeon. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002. / Includes bibliographical references. / (cont.) The elastic anisotropy and yield surfaces are fully characterized, and numerical equations are developed to allow the simple evaluation of the effect of geometric and material properties on the mechanical behavior of hollow-sphere foams. The analysis indicates that at relative densities of 10%, hollow-sphere foams have theoretical moduli and strengths that are three times those of existing metallic foams, and this increases to a factor of ten at relative densities below 5%. Several concepts are presented to allow the incorporation of defects into the model, including random packing, variations in bond size, and variations in sphere relative thickness. Finally, the performance of hollow-sphere foams is compared to other low-density engineering materials on a structural basis; hollow-sphere foams offer a beneficial alternative. / Metal foams are low-density materials with multifunctional attributes that make them appealing for numerous uses, including thermal insulation, heat sinks, acoustic insulation, energy absorption devices (crash protection), lightweight structural sandwich panels (as the core material), and vibration damping devices. Metallic foams are commercially available as closed-cell and open-cell foams. Unfortunately, the mechanical behavior of closed-cell metallic foams is far below that which the theory suggests; at low relative densities, the mechanical properties of closed-cell foams are an order of magnitude less than expected. It is shown that defects such as cell wall curvature, cell wall corrugation, and density variations account for a large fraction of the degradation in properties. Hollow-sphere foams offer a solution to the problem of degraded performance in closed-cell foams because ideal spheres can be bonded into a relatively defect-free structure. This thesis focuses on the development of constitutive models to describe the mechanical behavior of this new class of materials; such models are critical in determining whether or not hollow-sphere metallic foams provide an alternative to existing closed-cell metallic foam materials. The uniaxial compression behavior of single hollow spheres is first studied to determine the significant geometric and material parameters of hollow-sphere foams. Detailed constitutive models of the behavior of hollow-sphere foams are developed using finite element simulations of simple cubic, body-centered cubic, and face-centered cubic sphere packings. / by Wynn Steven Sanders. / Ph.D.