Materials Engineering & Nanotechnology Research

We synthesize polymer nanocomposites (PNCs), a novel class of multifunctional materials that are used in a variety of applications including high-tech fabrics, advanced optics, and enhanced photovoltaics. Optimization of PNC properties requires fine control over the interactions of hard nanoparticles or soft polymer droplets, which we tune by grafting polymers to their interfaces. Available projects focus on controlling the stretching of the graft polymer to increase nanoparticle or droplet interactions to develop new high strength, lightweight PNCs for biomedical, aerospace, and military applications.

Defining the active centers of heterogeneous catalysts with molecular precision offers opportunities to expand the scope of their reactivity. We are using our expertise in zeolite and doped-carbon synthesis to explore how heterogeneous catalysts can parallel the reactivity of molecular catalysts. At the same time, chemical interactions beyond the primary binding sites of catalysts can be critical for steering their reactivity and selectivity. We are working to understand, describe, and control these interactions that comprise the catalytic microenvironment.

When materials segregate into structures on the nanoscale new or unusual properties can result. The image shown is a transmission electron micrograph or a battery electrode material with elemental mapping where each color corresponds to a different element. Local segregation of elements and phases within the particle shown results in unusual electrochemical properties. Synthesis, characterization, and evaluation of novel nanomaterials are some of the major research efforts in our group.

Our experimental research program focuses on coupling molecular scale spectroscopic techniques with macroscopic transport measurements to gain fundamental insight into mechanisms of small molecule transport in polymers while providing design guidelines for preparing new and advanced polymers for membrane applications. In addition to characterization, we also prepare membranes from polymers that we have either functionalized or synthesized in our laboratory or that we have obtained from collaborative research efforts. We seek to understand how ion-polymer interactions and fundamental ion and polymer properties ultimately govern the transport properties of polymers.

At the nanoscale, quantum mechanical effects and various other mechanisms cause the properties of semiconductors to strongly depend on the size, shape and surface of the material. The widely tunable properties of semiconductor nanomaterials present many intriguing scientific questions as well as opportunities for transformative advances in technology. We are developing novel and advanced synthetic methods for colloidal quantum dots and nanostructured perovskites. We seek to understand and control the structure-property relationships in these novel nanomaterials as well as their self-assembled ensembles. Newly obtained insights are applied to fabrication and testing of prototype devices to demonstrate improved performance. Particularly, our efforts will be focused on solution processing based device fabrication methods to simultaneously achieve a low-cost and high performance required for wide spread commercial deployment.

We design materials that can recapitulate vital aspects of the native extracellular matrix (ECM), from mechanical and chemical cues, to the 3-dimensional and highly hydrated polymeric nature of soft tissue, to the dynamic feedback loop that exists between a cell and its native microenvironment. Gaining control of such factors using both engineered proteins and synthetic polymers allows us to independently tune aspects like stiffness and drug release that can greatly impact cellular fate. Our materials will instruct neural stem cell differentiation into useful neurons and oligodendrocytes as well as providing local and temporal control of growth factors to stimulate cell survival and proliferation.

Metal organic frameworks (MOFs) are an emerging class of materials that show promise for various applications such as sensing, catalysis, gas storage, separation and electronics. These materials are created by the synthesis of metal centers and organic molecule linkers into an ordered assembly, and combine the structural flexibility of organic crystals with large open pores that play a critical role in the aforementioned applications. However, MOF powders created through commonly used batch crystallization methods are not optimal for integration into applications, for example, as sensors, semiconductors, or ultra-low k dielectrics for electronics. These applications benefit from solution based, large area MOF production and deposition. Our lab focuses on crystal growth and reaction engineering of MOFs to create aligned crystals and thin films for use in various exciting fields, ranging from sensing and catalytic applications, to sparsely explored areas in electronics.

We work with naturally-derived polymers, including collagen and glycosaminoglycans such as hyaluronic acid, to engineer dynamic scaffolds, hydrogels, fibers, and particles. Through control of material properties including mechanics (stiffness, viscoelasticity), microstructure (pore size/shape, fiber diameter), and composition (ligand presentation) we can elucidate critical microenvironmental regulators of cell behavior. We then apply this knowledge to the development of new and improved materials for minimally invasive tissue engineering and therapeutic delivery.

By combining scalable and tunable synthetic polymers with biologically active peptides, we are designing materials that interact productively with biological systems. Peptides are inherently functional, providing sites for cell adhesion and metal binding, eradicating bacteria and directing molecular assembly. Embedding peptides within synthetic polymers, which offer a high degree of control over thermomechanical properties, molecular weight and composition, presents compelling opportunities to pattern cell adhesion, program shape changes or disintegration, and control mechanical properties in response to biological environmental cues. Such features are anticipated to enable 3D printing-based biomanufacturing and controlled release of therapeutics in next-generation biomaterials to provide personalized treatment strategies.