Engineering Commons^™

Nanoscale Deformation Of Composite Structures And Heterophase Interfaces, Shen Dillon

Composites at Lake Louise (CALL 2015)

Interfaces often govern the properties and performance of composite structures, especially in the context of mechanical response. However, nature of deformation in nanoscale composites and their interfaces requires improved understanding. We have been utilizing in-situ TEM based nanomechanics measurements to isolate individual heterophase interfaces and characterize their properties. Specific applications discussed relate to the role of alloy chemistry in affecting the interfacial strength in nanocomposites and the importance of interfacial deformation in affecting the wear resistance nanoscale tribofilms. The talk will also discuss the important role that nanoscale structural elements play in affecting overall composite properties.

Fabrication And Characterization Of Locally Resonant Acoustic Metamaterials Made With Resonators Generated From Core-Shell Drops, Carlos Martinez, Colton Steiner, C.T. Sun, Jeffrey Youngblood

Composites at Lake Louise (CALL 2015)

Acoustic metamaterials promise the remarkable ability to control, direct, and manipulate sound waves. Within this infant field, a promising approach to fabricate locally resonant acoustic metamaterials is the use of resonators composed of a heavy core surrounded by a rubber shell dispersed in an epoxy matrix. At the resonant frequency, the resonators vibrate 180° out-of-phase with the matrix and a band gap in transmission is observed making these materials excellent sound absorbers. The resonant frequency of the resonators scales with the core mass; therefore, it can be tailored by increasing the core diameter or the density of the core material. …

Reactive Ni-Al Nanostructured Composites Through Electrochemical Dispersion Deposition, Christopher Apblett, Jonathan Coleman, Robert Knepper, Alexander Tappan

Composites at Lake Louise (CALL 2015)

Reactive metal composites (RMC) films are used in various applications from precision joining and brazing to local high heat sources for power generation and local melting. They are gasless, high heat generating, high propagation speed reactions that involve the release of energy when elemental constituents are combined to make intermetallics. These films require solid state diffusion at the nanoscale to function well, and the current method of manufacture is to sputter 20-50nm thick alternating films of the reactant elements to build up a ~50um thick composite film. This process is slow and costly, and does not lend itself well to …

Imaging The Interphase In Polymer Composites, Jeffrey Gilman

Composites at Lake Louise (CALL 2015)

Polymer composites are currently used in aerospace, electronics and recreation. New uses are being explored in infrastructure, light-weight vehicles, and in alternative energy applications, such as solar and wind. Arguably, the most critical feature of a composite is the interface/interphase. The interphase in a polymer composite is the volume of polymer adjacent to the fiber interface, and it can comprise up to 30 % of the polymer when nano-scale additives are used. The interphase controls the effectiveness with which the nanoparticle and polymer interact to produce enhanced properties, but it remains a poorly characterized phase. Characterization of polymer dynamics …

Carbon Nanocomposites Structure And Properties: Insights From Tem Tomography, J. Alexander Liddle

Composites at Lake Louise (CALL 2015)

Despite the exceptional properties of individual carbon nanotubes (CNTs), it has proven difficult to produce composites that demonstrate the hoped-for property enhancements. The gap between expectation and reality can be closed by understanding the difference between the ideal morphology and those currently achievable. As a first step in improving our understanding of these materials, and establishing robust process-structure-property models to aid in their optimization, we have made detailed and accurate measurements of aligned multiwall-CNT/epoxy nanocomposite structure by energy-filtered transmission electron microscope (EFTEM) tomography. These tomographic images, together with novel image processing algorithms, are used to quickly generate accurate reconstructions of …

Design Of Multifunctional Composites And Their Use For The 3-D Printing Of Microsystems, Daniel Therriault

Composites at Lake Louise (CALL 2015)

Many of today's high-tech products are approaching their technological limits. For example, the microelectronics community is faced with overheating devices with a demand for compact three-dimensional (3D) architectures and lower power consumption, whereas the aerospace industry is seeking lighter, stiffer and more electrically conductive materials for the creation of more energy efficient aircraft. A promising solution is to capitalize on the amazing electrical, thermal and mechanical properties of some nanoscopic materials (one billionth of a meter). However, several challenges in material processing and manufacturing must be resolved, namely exploiting these properties at the industrial scale and overcoming the current planar …

Engineering Hydrogels For Dynamic Modulation Of Stem Cell Activity, Kristopher Kilian

Composites at Lake Louise (CALL 2015)

Patient derived mesenchymal stem cells (MSCs) are a promising cell-based autologous therapy for numerous diseases due to the propensity to differentiate to numerous lineages without risk of rejection. Another interesting aspect of the therapeutic potential of these cells is their proven ability to secrete molecules that are immunomodulatory and pro-angiogenic, e.g. living cytokine factories, which may be implanted at a site of injury to promote healing. However, clinical efficacy has proven to be variable, which we postulate is due in part to insufficient control over the injectable biomaterials employed. In our laboratory we have noted a gradual loss of the …

Additively Manufactured Bio-Based Composites, Jennifer Rodriguez, Cheng Zhu, Eric Duoss, Thomas Wilson, Christopher Spadaccini, James Lewicki

Composites at Lake Louise (CALL 2015)

The development of new materials solutions for advanced manufacturing and fabrication technologies is an increasing focus of many research and development efforts in applied materials science today. Advances in these areas are resulting in the development of novel, geometrically complex parts and functional devices in a multitude of arenas, such as the biomedical and aerospace industries. Recent progress in materials research includes; the development of polymer systems that are less reliant on petroleum-based products, and are instead based on renewable, bio-derived sources. Concurrently, new additive manufacturing (AM) technologies are allowing the production of complex parts with structures and physical response …

Layered Biomimetic And Kirigami Nanocomposites, Nicholas Kotov

Composites at Lake Louise (CALL 2015)

Finding materials with combinations of several extreme properties is one of the key requirements for the successful engineering of adaptive systems. Successful realization of such materials requires new choices for nanoscale components and new manufacturing approaches. Layer-by-layer assembly (LBL) is one of such technique that affords engineering of nanocomposite materials based on sequential adsorption of nanometer scale layers of polymers and inorganic particle, nanowires, nanotubes, sheets, etc. Importantly, it can lead to the materials with seemingly “impossible” combinations of physical properties encompassing mechanical, electrical, optical, and biological characteristics and distinct pathways to scalability. Hard-to-reach combinations of electrical and mechanical properties …

Transport Of Nanoparticles In Polyelectrolyte Solutions As A Model Of Polymer Nanocomposite Processing, Jacinta Conrad, Ryan Poling, Firoozeh Babaye, Ramanan Krishnamoorti

Composites at Lake Louise (CALL 2015)

The transport properties of nanoparticles in complex confined media play a significant role in the processing of advanced polymer nanocomposites. In polymer nanocomposite processing, nanoparticles suspended in polymer resins must be efficiently dispersed to obtain optimal mechanical, electrical, thermal, and/or optical properties and eliminate stress concentrators. Here, we investigate the diffusion and dispersion of nanoparticles in solutions of unentangled polyelectrolytes as a model system in which to understand the coupling between particle and polymer dynamics in flow conditions representative of those encountered during nanocomposite processing.

First, we measure the long-time quiescent diffusivity of fluorescent polystyrene nanoparticles in dilute and semidilute …

High Efficient Material And Process Combination For Future Aircraft Applications Based On Advanced Sheet Molding Compound Technologies, Marc Fette

Composites at Lake Louise (CALL 2015)

The increasing need for efficient passenger aircraft led to the development of innovative lightweight designs and an increasing demand on new lightweight materials such as carbon fiber reinforced plastics (CFRP) in the recent decades. Due to the high weight specific mechanical properties and the relatively high cost of raw materials, semi-finished and manufacturing the use of CFRP is limited on high performance applications, especially for components of the primary structures of aircraft.

Subsequently, fiber reinforced plastics (FRP) are also used in cabin and interior. Due to lower mechanical loads, but high requirements on fire protection, optics, surface and acoustics sandwich …

Supramolecular Peptide Composite Assemblies: Mimicking Biological Form And Function In Synthetic Systems, Erik Spoerke, Brad Jones, Jill Wheeler, Alina Martinez, Christina Ting, Mark Stevens

Composites at Lake Louise (CALL 2015)

Microtubules (MTs) are dynamic, multifunctional biomaterials that facilitate a range of complex biological process in cells ranging from regulation of cell morphology to separation of chromosomes during cell division to directing the intracellular transport of molecular cargo.¹ The remarkable precision, versatility, and dynamic nature of these non-equilibrium structures has motivated our desire to mimic their structure and function in synthetic materials. Here, I will identify a number of the key attributes responsible for MT form and function, and describe our efforts to merge computation and experiment to design, synthesize, and study a family of self-assembling peptides intended to mimic …

Aptamer Panning Against Gold, Valeria Milam, Maeling Tapp, Richard Sullivan, Patrick Dennis, Rajesh Naik

Composites at Lake Louise (CALL 2015)

Oligonucleotide aptamers are single-stranded sequences that exhibit high affinity and specificity for a particular non-nucleotide target including, but not limited to small molecules, proteins, and even whole cells. Aptamers are conventionally isolated and identified using a multi-round screening approach called "Systematic Evolution of Ligands by Exponential Enrichment" (SELEX) in which a pool of approximately 10⁹ random candidate sequences is continuously enriched with amplified copies of “winning” sequences or adsorbates from prior selection rounds. While SELEX has revolutionized the discovery of numerous DNA and RNA-based aptamers for a variety of targets and dominated the field for two decades as a …

Click Chemistry And Its Unique Benefits In Composite Formulation, Christopher Bowman, Maciej Podgorski, Chen Wang, Shunsuke Chatani

Composites at Lake Louise (CALL 2015)

Although proposed only 15 years ago, “click” chemistry has already become a powerful tool in many synthetic/preparatic schemes in polymer science. The simplicity and robustness of “click” chemistries render them ideal candidates in engineering composite materials with well-defined physiochemical properties for vast range of applications. Herein we present the advances in the implementation of thiol-X “click” chemistries in various composite materials, exemplified by dental restoration materials, shape memory programmable composites/laminates and latex composite materials. In the first example, we developed a series of thiol-ene monomers in which esters are absent so that they are hydrolytically stable in basic conditions. We …

Scalable Directed Assembly Of Nanostructured Soft Materials, Chinedum Osuji

Composites at Lake Louise (CALL 2015)

Molecular self-assembly of block copolymers and small molecule surfactants gives rise to a rich phase behavior as a function of temperature, composition, and other variables. The ability to precisely control their chemical functionality combined with the readily tunable characteristic length scales (~1-100 nm) of their self-assembled mesophases identifies these systems as a versatile and attractive class of materials for compelling applications ranging from selective transport to lithography. A longstanding problem in this area is the inability to reliably and rapidly generate well-ordered structures with specified orientations in, and over, application-relevant geometries, and dimensions, respectively, i.e. to direct their self-assembly in …

The Development Of Bioresorbable Fe-Mn Alloys For Orthopedic Implantation, Lia Stanciu

Composites at Lake Louise (CALL 2015)

Bioresorbable metals have immense potential to be used in the clinical treatment of a variety of soft and hard tissue injuries and disease. For many applications, the presence of a permanent device may cause severe negative effects and require re-intervention in the long-term. A transient support for a healing tissue is an attractive solution for orthopaedic and vascular interventions alike. For applications in bone fracture in particular, the human body requires fixation devices to support bone regrowth in the proper alignment, but only for a short period of time (typically 6-12 months). We aim to design bioresorbable materials to fill …

Towards Accelerated Medical Innovation, Jeff Karp

Composites at Lake Louise (CALL 2015)

This talk will explore platform technologies that are currently being developed in the KarpLab at the Brigham and Women’s Hospital, Harvard Medical School, to tackle medical problems. Namely, minimally invasive sealing of tissues and wounds including blood vessels and heart tissue, achieving long term local immunosuppression for treatment of vascularized composite allografts, and engineered stem cell therapy for treatment of diseases such as multiple sclerosis and prostate cancer. Many of the technologies developed in the Karplab harness lessons from nature for inspiration, as evolution represents millions and millions of years of research and development and thus nature truly is the …

Three-Dimensional Printing Of Graphene-Based Composite Aerogels, Chen Zhu

Composites at Lake Louise (CALL 2015)

Graphene-based composite materials have found wide applications in nanoelectronics, sensors, catalysis, energy storage, and biomedicine areas for their unique combination of low density, exceptional mechanical properties, large surface area, and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, by the self-assembly or gelation of the graphene oxide (GO) suspension via hydrothermal reduction, chemical reduction, or direct crosslinking of the GO sheets. Other templating methods like chemical vapor deposition (CVD) coatings and freeze-casting have already been employed to control over the pore morphology of 3D graphene monoliths. However, the architecture of these graphene …