Matteo Pasquali, Rice University


Matteo Pasquali directs the laboratory cf2 (complex flows of complex fluids). The laboratory's research revolves around understanding the interaction of flow and liquid micro- and nano-structure in complex fluids, with a focus on the processing of multifunctional materials and the manufacturing of soft conductors, particularly based on Carbon Nanotubes (CNTs) and graphene. The laboratory targets applications in energy transmission and harvesting, biomedicine, petroleum, aerospace and defense. The cf2 group has made fundamental and applied advances on the manufacturing of CNT and graphene fibers, thin films, coatings, and foams, the behavior of liquid crystalline phases of CNTs and graphene, the dynamics of individual CNTs in fluids and confined environments, the interaction of CNTs with electromagnetic fields, the effect of flow on flexible and semiflexible molecules, the mechanics of blood cells in blood pumps, the rheology of attractive emulsions, and the application of finite elements, large-scale parallel computing, and thermodynamics projections in modeling flows of complex fluids occurring in microfluidics, coating, ink-jet printing, medical devices, and material processing. Current research efforts include understanding and improving the manufacturing and performance of CNT fibers, the effect of CNT length on CNT fibers and films, the liquid phase behavior and flow of CNTs, graphene, and graphene oxide solutions, the formation of three-dimensional solid structures (foams and sponges) of CNTs and graphene, the dynamics and detection of CNTs in porous media (with application to oil sensing and recovery and biomedicine), the dynamics of viscoelastic filaments in the presence of wetting and dewetting forces, the behavior of blood cells in implantable flow devices, and various applications of CNT fibers to field emission, data cables, power transmission, thermal management, and medicine. Prof. Pasquali earlier research interests include theoretical and experimental studies of free surface flows of polymer solutions and the dynamics of semiflexible polymers. The cf2 group research includes collaborations with international groups in France (CNRS and Université Bordeaux), the Netherlands (Teijin Aramids, Vrije Universiteit Amsterdam and TU Eindhoven), Germany (RWTH Aachen and Georg-August-Universität Göttingen), Italy (Università di Roma), Israel (Technion), Brazil (PUC Rio), Japan (Nitto), and Australia (Monash University), as well as US collaborations with the Air Force Research Laboratory, the National Institute of Standards & Technology, NASA, University of Massachusetts at Amherst, University of Colorado at Boulder, and the University of Minnesota. The cf2 group is funded (about $1.4M/yr) by government agencies (including Department of Defense, National Science Foundation, National Institutes of Health, and National Institute of Standards & Technology), foundations (Welch Foundation), and companies and industry (Teijin Aramids, Lockheed-Martin, Saudi Aramco, and Nitto). Prof. Pasquali co-directed the Carbon Nanotechnology Laboratory (CNL) during the two-year period (2006-2008) following the death of CNL’s founder Prof. Rick Smalley (1996 Nobel); Prof. Pasquali oversaw the transition of CNL into a shared facility within the Smalley Institute for Nanoscale Science and Technology. From 2009 to 2014, Prof. Pasquali served as Master of Lovett College, one of the 11 Residential Colleges of Rice University. Prof. Pasquali is presently serving as Chair of the Department of Chemistry. For more information, see the website of Prof. Pasquali's research group at pasquali.rice.edu, Prof. Pasquali’s profile on ResearcherID and Google Scholar, and the websites of Lovett College and the Department of Chemistry.

 

Abstract:

Soft, lightweight conductors from nanoscale carbon

 

Matteo Pasquali

Department of Chemical & Biomolecular Engineering

Department of Chemistry

Department of Materials Science & NanoEngineering

The Smalley Institute for Nanoscale Science & Technology

The Ken Kennedy Institute for Information Technology

Rice University, Houston, TX 77005

mp@rice.edu

 

Certain materials properties are viewed as contradictory. For example, high electrical and thermal conductivity are associated to hard, crystalline materials such as metals or graphite. Conversely, softness is associated with biological materials, polymers, colloids, and disordered structures, which are also thermally and electrically insulating. We have essentially accepted that certain ostensible contradictions cannot be resolved. For example, we have no material that is electrically conductive like a metal and can be sutured or sewn, despite the obvious need in medical devices and wearable electronics.

Nanoscale carbon—including Carbon Nanotubes (CNTs) and graphene—has remarkable electrical, thermal, and mechanical properties; thus, it is uniquely suited as building block for novel conductors. Yet, broad applications of nanoscale carbon to real-world problems have largely gone unfulfilled because of difficult material synthesis and laborious processing. This hurdle can be overcome by treating CNTs and graphene as hybrids between polymer molecules and colloidal particles and designing fluid-phase directed assembly routes for soft conductors.

Even at minute concentrations, CNTs form complex fluid phases with intriguing properties. In crowded environments (e.g., gels), CNTs reptate like stiff polymers; surprisingly, the small bending flexibility of CNTs strongly enhances their motion. CNTs and graphene can be solution-processed in strong acids, their sole true solvents. At low concentration, these fluids can be used for making transparent, conducting, flexible films and coatings, as well as highly porous, soft three-dimensional structures (foams). At high concentration, CNTs and graphene form liquid crystals that can be scalably spun into high-performance multi-functional fibers. These CNT fibers combine the high conductivity, strength, and the emergent property of softness; they are already finding high-value applications in aerospace electronics, Hi-Fi cables, and field emission. As soft conductors, CNT fibers provide a natural interface to the electrical function of the body as restorative sutures for electrically damaged heart tissue as well as electrodes for stimulating and sensing the activity of the brain. Fluid processing allows the direct coating of shielding conductors in coaxial cables; in test cases (MIL C-17), directly coated CNT shielding meets the attenuation standard while rendering the shielding layer essentially immaterial in the total mass of the cable and improving the cable flex fatigue.