Songlin Zhang
Non-metal conductors: C conductors (Carbon nanotube/graphene)
Entangled CNT network conductivity was much lower than their intrinsic properties due to the inter-tube contacts. Previous research showed higher conductivity, however, it was achieved in smaller scale samples ~ 10 micron. In this project, we overcome these limits using mechanical stretching of CNT sheet and iodine doping and conductivity over 10,000 Scm-1 was achieved at continuous roll of CNT strip. Also, the conductivity was stabilized with the conducting polymer (PEDOT:PSS) coating and expand the applicability of this CNT strip.
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Corrosion/oxidation resistance
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Lightweight solution for deep-space exploration
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High performance to be used as power/signal transmission lines/cables
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Expanded options of resources
Carbon/carbon (C/C) matrix composite with nano-reinforcement
We fabricated lightweight and high strength “carbon nanotube/carbon” composite fiber from the CNT ribbon. Polydopamine (PDA) was used to coat the surface of CNT and phenolic resin was infused and pyrolyzed for carbon matrix. With the additional adhesion layer of PDA, the resulting “CNT/py-PDA/C” composite fiber exhibited improved mechanical properties and electrical conductivities compared to regular “CNT/C” composite. We studied the physical properties as a function of PDA deposition time, carbonization temperatures up to 1200 C as well. A brief demonstration of “CNT/py-PDA/C” with high mechanical and electrical properties for lifting mass and lighting LED was also included at the end. Our findings could be applied for various carbon/carbon composite applications.​
Atomic characterization of composite interface
Taking the advantage of high-resolution Scanning/Transmission Electron Microscopy (S/TEM), the interface area of CNT composite can be analyzed at nano- and atomic-scale with qualitative and quantitative information. First, the change of chemical bonds on the surface of CNT before and after functionalization (f-CNT) and the interactions between f-CNT and polymer matrix can be quantitatively characterized by advanced electron energy loss spectroscopy (EELS/mapping) technology. Second, chemical composition and distribution can be easily and accurately obtained using energy filtered TEM (EFTEM). Third, these technologies can be readily used for the various characterization of many other nanocomposites.
Flexible conductors for next-generation electronics
The development of next-generation wearable electronics requires the advance of stretchable and flexible electrical conductors. Conventionally, rubber-like polymer matrix and conductive fillers are combined together to achieve high mechanical stretchability and good electrical performance. In this project, we are going to expand the option of polymer matrix using a newly developed polyacrylonitrile (PAN) rubber which is cross-linked by silver nitrate (AgNO3). This new rubber shows a good intrinsic sensitivity to mechanical strain. After filled with silver flakes, this new stretchable conductor demonstrates an excellent stretchability and high conductivity at high strain (unpublished).