Browsing by Author "Saha, Avishek"

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    Engineering Single Walled Carbon Nanotube Assemblies: From Ruthenium Complexes Assisted Dispersions to Networks on Different Platforms
    (2013-08-07) Saha, Avishek; Marti, Angel A.; Tour, James M.; Pasquali, Matteo
    Manufacturing large area networks have potential applications in electronic devices such as thin film transitors, transparent conductive electrodes, and organic photovoltaics among others. The design of two-dimensional SWCNT networks necessitates addressing the challenges of nanotube individualization and organization of networks on different scaffolds. Chapter 1 describes a comprehensive overview of ongoing research in the field of nanotube networks on different platforms. Efficient individualization of SWCNTs in chlorosulfonic acid (CSA) has been reported earlier but preparation of networks on suitable scaffolds still requires attentions. To address that, we have demonstrated a simple solution based technique to produce SWCNTs networks. Chapter 2 describes the deposition of protonated SWCNTs (p-SWCNTs) on the external surface of porous materials. SWCNTs are dispersed in CSA via protonation before the deposition and placed in contact with mesoporous and microporous silicates. Furthermore, the nanotubes are deprotonated using vinyl pyrrolidone, while immobilized resulting in a network of mostly individual pristine SWCNTs on the surface of microporous and mesoporous materials. In chapter 3, we applied a solution-based approach to design thin films on the surface of non-porous silica. SWCNTs networks were formed on fused silica using a simple, efficient dip coating technique. We found the properties of these networks could be tuned by changing the density of SWCNTs in the network. For example, when we prepared low-density films, NIR photoluminescence from individual SWCNTs was observed on the surface of fused silica after deprotonation with diethyl ether. Our findings also support the arguments of reversible protonation of sidewall of SWCNTs during dispersion by CSA. Finally, for high-density films, we achieved sheet resistance of 471 Ω/Sq with 86% transparency. The opto-electronic performance of our films was compared with other recent works reported in literature. Chapter 4 presents the aqueous dispersion of SWCNTs using non-photoluminescent ruthenium polypyridyl complexes with extended -systems by non-covalent dispersion. We further used photoluminescent complexes, which cannot only disperse SWCNTs but can also be monitored in photo-excited state to achieve photo-excited electron transfer processes with potential applications to light harvesting. In the final chapter, a study was reported on the vapoluminescence of encapsulated rhenium metal complexes in zeolite supercages. Upon exposure to solvent vapors, the hybrid materials show characteristic emission maxima, intensity and lifetime decay. This work shows detection of solvent vapors in a simple unambiguous way, which may find applications in the area of sensing.
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    Immobilized carbon nanotubes on various surfaces
    (2015-08-04) Marti-arbona, Angel A.; Saha, Avishek; Pasquali, Matteo; Rice University; United States Patent and Trademark Office
    In some embodiments, the present invention provides methods of immobilizing carbon nanotubes on a surface, wherein the method comprises: (1) mixing carbon nanotubes with a superacid to form a carbon nanotube solution; and (2) exposing the carbon nanotube solution to the surface. The exposing results in the immobilization of the carbon nanotubes on the surface. In some embodiments, the method occurs without the utilization of carbon nanotube wrapping molecules. Other embodiments of the present invention pertain to systems that comprise immobilized carbon nanotubes on a surface, as developed by the aforementioned methods.
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    Liquid crystals from single-walled carbon nanotube polyelectrolytes and their use for making various materials
    (2016-02-02) Marti-arbona, Angel A.; Jiang, Chengmin; Saha, Avishek; Pasquali, Matteo; Young, Colin; Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure pertains to methods of forming a solution of single-walled carbon nanotube polyelectrolytes in a liquid crystalline phase. In some embodiments, such methods comprise: (a) providing single-walled carbon nanotube polyelectrolytes; and (b) mixing the single-walled polyelectrolytes with a polar aprotic solvent to form a mixture, where the mixing results in the formation of single-walled carbon nanotubes in the liquid crystalline phase. In some embodiments, the polar aprotic solvent comprises crown ether. In some embodiments, the present disclosure pertains to a method of making single-walled carbon nanotube fibers. Further embodiments of the present disclosure pertain to a method of making a single walled carbon nanotube composite. In some embodiments, the present disclosure pertains to an article comprising neat aligned carbon nanotubes.