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Sunday, February 3, 2019 at 4:00pm to 5:00pm
Bard Hall, 140
MSE Seminar 2/3; 140 Bard Hall @ 4:00pm (Note room change)
University of California, Berkeley
From Carbon Nanotube Liquid Crystalline Solutions to Functional Fibers
Design and development of smart and active materials across different length scales have been a long-standing challenge in materials processing. Conventional materials are often limiting in the number of simultaneous functionalities they offer in addition to their passive behavior in response to external stimuli. However, chemical methods developed over the past decades have enabled synthesis of new classes of nanomaterials. Self-assembly of such nanoscale building blocks leveraging fluid phase processing methods have provided a unique opportunity to realize a new generation of functional materials.
In this talk, I will use carbon nanotubes (CNTs) as example building blocks that can be fluid phase processed into larger scale functional materials and integrated into active devices. CNTs possess a remarkable combination of electrical, thermal, and mechanical properties. Yet, realizing these properties at the macroscale, requires a fundamental understanding and controlling of the morphology and the phase behavior of their solutions. High concentration solutions of CNTs form a nematic liquid crystalline phase which can be processed into macroscopic materials such as multifunctional fibers. Here, I first present our results on quantitative understanding of the morphology of the liquid crystal phase and that how the alignment is affected by the CNT properties and concentration. The natural orientational alignment of CNTs within the nematic phase would highly impact the alignment of CNTs in fibers, improving the electrical and mechanical properties. Wet-spun CNT fibers combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. Given these properties, CNT fibers can serve as a structural support onto which functional materials can be deposited to develop active optoelectronics. Using light-emission as an example, next I will discuss our approach to transform CNT fibers to active devices.