Materials Day Agenda 2008

Materials that can self-assemble are becoming the key building blocks of various advanced nanotechnologies based on “bottom up” fabrication methods. Self-organizing materials provide simple and low-cost processes to make large-area periodic nanostructures. Alternatively, the conventional “top-down” lithographic approaches offer superior nanometer-level precision and accuracy. By combining “bottom-up” self-assembly with “top-down” patterned templates, templated self-assembly (TSA) provides rich opportunities for fundamental studies of self-assembly behavior in confined environments, as well as a source of innovation in nanofabrication methods that benefit from the advantages of both “bottom-up” and “top-down” approaches. Self-assembly has been the focus of much research in the last four decades. These efforts have produced a solid foundation of understanding in the physics and chemistry of self-organizing processes in the bulk. Sophisticated lithographic tools enabling complex 3D structures for the microelectronic industry have also been developed during this time. Only recently have researchers sought to bring the two fields together. Templated self-assembly (TSA) is a method of inducing long range order in thin films of materials using artificial topographical and/or chemically-patterned templates. In contrast to conventional epitaxy in which the lattice of a thin film bears a well-defined relationship to the lattice of the underlying substrate, templates for TSA are not required to be crystalline materials. In the concept of templated self-assembly, the topography and/or chemical pattern of the templates instead of the atomic lattice of the substrate are used to guide the reorganization of self-assembled materials. The characteristic feature size of templates in TSA, LS, ranges from the same order-of-magnitude as the characteristic length, L0, of the self-assembled materials to much larger than L0.   Block copolymers have been used as a low-cost nanopatterning tool to make nanodot arrays, nanowire arrays, decoupling capacitors, nanocrystal-based flash memory and catalysts for growing carbon nanotubes. Beyond the applications of short-range ordered nanostructures from typical block copolymer films, templated block copolymers provide well-registered nanostructures and can serve as alternative lithographic tools for nanofabrication applications requiring good dimensional control, pattern registration and low line-edge roughness. Programmable self-assembled block copolymer nanostructures can be achieved by both chemical and topographic substrate patterns. The integration of these templated self-assembly processes into devices has begun, for example in the fabrication of patterned magnetic media for high density magnetic recording. We believe that the use of block copolymers will be appropriate in a wide range of applications as a vehicle to introduce functional groups or functional materials with precise spatial control. For example the incorporation of nano-objects into block copolymers can provide a simple route to control the spatial distribution and orientation of nanoparticles and nanowires and provide ways to create complex hierarchical structures and devices.

Our laboratory is interested in the design of materials that ‘interface’ with the immune system, in order to (1) create model systems for the study of lymphocyte biology and (2) to develop new immunotherapies that direct the immune system against cancer or infectious diseases.  Because biological systems are naturally hierarchical, with structural organization starting at the macroscale (entire organs/tissues) spanning down to the nanoscale (assemblies of proteins), we hypothesize that biomaterials designed to mimic native tissue or achieve therapeutic should likewise exhibit properties engineered across diverse length scales.  An example of how we are attempting to apply this idea to immunotherapy will be discussed:  Injectable gel materials that can deliver therapeutic immune cells to solid tumors have been developed.  These macroporous matrices are combined with microparticles that locally modulate the properties of the matrix and release nanoparticles that interact with individual cells in the microenvironment on the nanoscale.  Together, these complex materials offer new possibilities for manipulating the host response to cancer.

This presentation will focus on recent work developing nano-engineered advanced composites.  These hybrid composites employ aligned carbon nanotubes (CNTs) to enhance laminate-level multifunctional properties of existing aerospace-grade advanced composites. Intrinsic and scale-dependent characteristics of the CNTs are used to engineer laminate-level property improvements: interlaminar shear strength, toughness, and electrical conductivity results will be discussed and the underlying mechanisms elucidated. Fundamental studies on polymer-CNT interactions led to the development of a combined top-down and bottom-up fabrication methodology that addresses several of the key issues (agglomeration, viscosity, CNT wetting, scale, alignment) that have frustrated the use of CNTs in nanocomposites and nano-engineered composites. Current research to answer key outstanding “questions of the day” related to CNT contributions to composite properties are discussed, including a novel experimental platform to investigate nanoscale interactions in a well-controlled manner. New research directions stemming from the ongoing work will be suggested.

Modern extractive metallurgy with its almost total reliance on carbon as a reducing agent is intrinsically incapable of achieving sustainability. For example, it takes ½ ton of carbon to make a ton of steel. With annual global steel production of 1.4 billion tons this means the steel industry consumes 700 million tons of carbon producing over 1.7 billion tons of carbon dioxide per year. Among the by-products are hazardous air pollutants (HAPs) including metals (primarily manganese and lead) and trace amounts of organic HAPs (such as polycyclic organic matter, benzene, and carbon disulfide). Molten oxide electrolysis (MOE), which is the electrolytic decomposition of a metal oxide into molten metal and oxygen gas, represents an alternative to today’s carbon-intensive thermochemical reduction processes. For MOE the feedstock can be concentrate derived from ore or can be hazardous waste such as chromate sludge. The process avoids the use of consumable carbon anodes; this eliminates the need for energy-intensive anode manufacture and guarantees the absence of greenhouse-gas emissions as the by-product of the metal-recovery step. Feeding the electrolysis cell and harvesting the products can be done in such a way as to allow continuous operation. The concept applies to a variety of chemistries including titanium, ferroalloys (including stainless steel), beryllium, lanthanons or rare-earth metals (e.g., neodymium), and uranium. For these metals, then, molten oxide electrolysis offers an environmentally friendly technology that has the potential to be more cost efficient than current practice.

After water concrete is the material the most consumed on Earth. The current cement production stands at 2.9 billion tons, enough to produce more than 20 billion tons of concrete, or one cubic meter per capita and year on Earth. There is no other material on the horizon that could replace concrete as the backbone material of our society to meet its legitimate need for housing, shelter, hospitals, schools, infrastructure and so on. But concrete faces an uncertain future due to its high environmental footprint accounting for some 10% of the worldwide Co2 emissions. A true shift in paradigm is required in order to meet these concrete challenges. In this talk, I will present some recent research results on the nanostructure of concrete that can ultimately lead to reducing the environmental footprint of cement-based materials. I will show that C-S-H, the cohesive binding phase of all cementitious materials exists in at least two distinct form, a low-density and a high-density phase, which merely differ in their characteristic packing density. This type of nanogranular behavior is not only found for C-S-H, but seems to be a general characteristic of many natural composites, namely bone and clay. There are lessons to be learned from this general pattern of natural composites for the development of the next generation of sustainable construction materialsProfessor

By 2050 the world population will reach over 9 billion and “flattening of the world” will be an understatement. We anticipate burgeoning needs regarding energy resources, transportation, housing, food distribution/packaging for the masses, recycling, and health care/ health care delivery, not to mention climate change and environmental issues. The issues we face today will be insignificant to what we may expect if we (Global Society) do not act. World population is increasing at an average rate of 1.4%, and in contrast world energy consumption is increasing at an average rate of 1.7%. Such an imbalance is not sustainable and requires action. From a societal perspective, engineers have played a major role to enhance the quality of life in our world. Sustainable development in the 21st Century is perhaps the most critical issue we face. Resources are finite and it requires innovations as well as governmental policies. Solution paths – via Materials Science and Engineering- for a sustainable development in this Century will be presented and discussed.

As nanotechnology moves from development to commercialization, there has been growing interest in understanding potential environmental health and safety risks associated with various nanomanufacturing processes.  Recent papers indicate that engineered nanomaterials may present potential risks to human health. The objectives of this work are to probe and assess the issues that will have direct implications for the some of the nanomanufacturing technologies under development.  Results will help to guide the overall development of a sustainable production system for nanomanufactured products. Five distinct, yet complementary research areas are under investigation to address societal implications of nanotechnology that concentrate on nanomanufacturing with goals to: 1) ensure that CHN laboratories are using best-practice industrial hygiene, and perform fundamental research on methods to measure and control nanoparticles exposures; 2) assess the current regulatory capacity and expected needs in the Commonwealth of Massachusetts for commercial production; 3) evaluate applications of nanotechnology on their likelihood to promote or compromise environmental values; and 4) create methodologies to determine the economic feasibility of manufacturing in light of potential environmental consequences for scale-up of technologies. 

The choice of material has potentially sweeping implications on product realization. Materials selection will affect not only properties, but will also dictate available production processes, and, therefore, potential product form. Furthermore, the synergies among design, materials, and process delimit and, potentially, prescribe the environmental impacts associated with a product's manufacture, its use, and its ultimate disposal.
As such, improving the sustainability of the products and materials we use will require that engineers have access to methods and tools that characterize the economic and environmental implications of design decisions throughout the product / material system.
This presentation will review several current research projects that are attempting to fill this need for evaluation tools. This will include 1) a historic case analysis of limited materials availability to better understand the implications to the firm of sustainable materials use; 2) a review of methods to model the cost of novel materials technologies; and 3) the use of modeling methods to identify technological and operational strategies that improve the potential recyclability of materials.