Browsing by Author "Khabashesku, Valery N."
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Item Condensation polymers having covalently bound carbon nanotubes(2013-03-19) Khabashesku, Valery N.; Rice University; United States Patent and Trademark OfficeThe present disclosure describes carbon nanotube materials and condensation polymers having at least one bridge between carbon nanotubes. Carbon nanotube materials comprise a plurality of functionalized single-wall carbon nanotubes linked to at least one other single-wall carbon nanotube by at least one bridge. The at least one bridge comprises at least one amine functionality bonded to the functionalized single-wall carbon nanotubes. The amine functionality may be alkyl or aryl. Carbon nanotube condensation polymers having at least one bridge between single-wall carbon nanotubes are also disclosed. The bridges in the condensation polymers comprise an amine functionality and a condensation agent.Item Direct gas fluorination of boron nitrides and compositions including fluorinated boron nitrides(2024-02-13) Khabashesku, Valery N.; Meiyazhagan, Ashok Kumar; Ajayan, Pulickel M.; Rice University; Baker Hughes Oilfield Operations LLC; United States Patent and Trademark OfficeA method for producing fluorinated boron nitride involves heating a reactor chamber, providing boron nitride in the reactor chamber, flowing fluorine and an inert gas through the reactor chamber, and exposing the boron nitride to the flowing gases and the heat. The method may include boron nitride that is exfoliated or non-exfoliated. The fluorinated boron nitride that is produced from this method may have a hexagonal crystal structure or a cubic crystal structure. The method may additionally comprise removing the fluorinated boron nitride from the reactor chamber and mixing it with a surfactant. A suspension may comprise particles of fluorinated boron nitride suspended in a fluid, which may be polar or non-polar, and may additionally include a surfactant. The fluorinated boron nitride may have a hexagonal or a cubic crystal structure. Furthermore, the boron nitride may be exfoliated or non-exfoliated.Item Energy storage devices including at least one electrode comprising a metal diboride, and related methods(2020-09-15) Zhou, Zhou; Kato, Keiko; Babu, Ganguli; Khabashesku, Valery N.; Ajayan, Pulickel M.; Rice University; Baker Hughes, a GE company, LLC; United States Patent and Trademark OfficeAn energy storage device including a first electrode comprising lithium, a second electrode comprising a metal diboride, an electrolyte disposed between the first electrode and the second electrode and providing a conductive pathway for lithium ions to move to and from the first electrode and the second electrode, and a separator within the electrolyte and between the first electrode and the second electrode. A method of forming an energy storage device including forming a first electrode to include lithium, forming a second electrode to include a metal diboride, disposing an electrolyte between the first electrode and the second electrode, the electrolyte providing a conductive pathway for lithium ions to move to and from the first electrode and the second electrode, and disposing a separator within the electrolyte and between the first electrode and the second electrode.Item Fabrication of carbon nanotube reinforced epoxy polymer composites using functionalized carbon nanotubes(2009-10-13) Khabashesku, Valery N.; Zhu, Jiang; Peng, Haiqing; Barrera, Enrique V.; Margrave, John L.; Margrave, Mary Lou; Rice University; United States Patent and Trademark OfficeThe present invention is directed to methods of integrating carbon nanotubes into epoxy polymer composites via chemical functionalization of carbon nanotubes, and to the carbon nanotube-epoxy polymer composites produced by such methods. Integration is enhanced through improved dispersion and/or covalent bonding with the epoxy matrix during the curing process. In general, such methods involve the attachment of chemical moieties (i.e., functional groups) to the sidewall and/or end-cap of carbon nanotubes such that the chemical moieties react with either the epoxy precursor(s) or the curing agent(s) (or both) during the curing process. Additionally, in some embodiments, these or additional chemical moieties can function to facilitate dispersion of the carbon nanotubes by decreasing the van der Waals attractive forces between the nanotubes.Item Femtosecond Er-Doped All-Fiber Laser with High-Density Well-Aligned Carbon-Nanotube-Based Thin-Film Saturable Absorber(MDPI, 2022) Dvoretskiy, Dmitriy A.; Sazonkin, Stanislav G.; Orekhov, Ilya O.; Kudelin, Igor S.; Denisov, Lev K.; Karasik, Valeriy E.; Agafonov, Viatcheslav N.; Khabashesku, Valery N.; Davydov, Valeriy A.We have studied the ultrafast saturation behavior of a high-density well-aligned single-walled carbon nanotubes saturable absorber (HDWA-SWCNT SA), obtained by a high-pressure and high-temperature treatment of commercially available single-wall carbon nanotubes (SWCNTs) and related it to femtosecond erbium-doped fiber laser performance. We have observed the polarization dependence of a nonlinear optical saturation, along with a low saturation energy level of <1 fJ, limited to the detector threshold used, and the ultrafast response time of <250 fs, while the modulation depth was approximately 12%. We have obtained the generation of ultrashort stretched pulses with a low mode-locking launching threshold of ~100 mW and an average output power of 12.5 mW in an erbium-doped ring laser with the hybrid mode-locking of a VDVA-SWNT SA in combination with the effects of nonlinear polarization evolution. Dechirped pulses with a duration of 180 fs were generated, with a repetition rate of about 42.22 MHz. The average output power standard deviation was about 0.06% RMS during 3 h of measurement.Item Fiber-reinforced polymer composites containing functionalized carbon nanotubes(2012-05-29) Zhu, Jiang; Khabashesku, Valery N.; Peng, Haiqing; Barrera, Enrique V.; Margrave, John L.; Margrave, Mary Lou; Rice University; United States Patent and Trademark OfficeThe present invention is directed to methods of integrating carbon nanotubes into epoxy polymer composites via chemical functionalization of carbon nanotubes, and to the carbon nanotube-epoxy polymer composites produced by such methods. Integration is enhanced through improved dispersion and/or covalent bonding with the epoxy matrix during the curing process. In general, such methods involve the attachment of chemical moieties (i.e., functional groups) to the sidewall and/or end-cap of carbon nanotubes such that the chemical moieties react with either the epoxy precursor(s) or the curing agent(s) (or both) during the curing process. Additionally, in some embodiments, these or additional chemical moieties can function to facilitate dispersion of the carbon nanotubes by decreasing the van der Waals attractive forces between the nanotubes.Item Fluorinated h-BN as a magnetic semiconductor(American Association for the Advancement of Science, 2017) Radhakrishnan, Sruthi; Das, Deya; Samanta, Atanu; de los Reyes, Carlos A.; Deng, Liangzi; Alemany, Lawrence B.; Weldeghiorghis, Thomas K.; Khabashesku, Valery N.; Kochat, Vidya; Jin, Zehua; Sudeep, Parambath M.; Martí, Angel A.; Chu, Ching-Wu; Roy, Ajit; Tiwary, Chandra Sekhar; Singh, Abhishek K.; Ajayan, Pulickel M.We report the fluorination of electrically insulating hexagonal boron nitride (h-BN) and the subsequent modification of its electronic band structure to a wide bandgap semiconductor via introduction of defect levels. The electrophilic nature of fluorine causes changes in the charge distribution around neighboring nitrogen atoms in h-BN, leading to room temperature weak ferromagnetism. The observations are further supported by theoretical calculations considering various possible configurations of fluorinated h-BN structure and their energy states. This unconventional magnetic semiconductor material could spur studies of stable two-dimensional magnetic semiconductors. Although the high thermal and chemical stability of h-BN have found a variety of uses, this chemical functionalization approach expands its functionality to electronic and magnetic devices.Item Fluorinated Multi-Walled Carbon Nanotubes Coated Separator Mitigates Polysulfide Shuttle in Lithium-Sulfur Batteries(MDPI, 2023) Salpekar, Devashish; Dong, Changxin; Oliveira, Eliezer F.; Khabashesku, Valery N.; Gao, Guanhui; Ojha, Ved; Vajtai, Robert; Galvao, Douglas S.; Babu, Ganguli; Ajayan, Pulickel M.Li-S batteries still suffer from two of the major challenges: polysulfide shuttle and low inherent conductivity of sulfur. Here, we report a facile way to develop a bifunctional separator coated with fluorinated multiwalled carbon nanotubes. Mild fluorination does not affect the inherent graphitic structure of carbon nanotubes as shown by transmission electron microscopy. Fluorinated carbon nanotubes show an improved capacity retention by trapping/repelling lithium polysulfides at the cathode, while simultaneously acting as the “second current collector”. Moreover, reduced charge-transfer resistance and enhanced electrochemical performance at the cathode-separator interface result in a high gravimetric capacity of around 670 mAh g−1 at 4C. Unique chemical interactions between fluorine and carbon at the separator and the polysulfides, studied using DFT calculations, establish a new direction of utilizing highly electronegative fluorine moieties and absorption-based porous carbons for mitigation of polysulfide shuttle in Li-S batteries.Item Fluorinated nanodiamond as a precursor for solid substrate surface coating using wet chemistry(2011-08-23) Khabashesku, Valery N.; Liu, Yu; Halas, Nancy J.; Rice University; United States Patent and Trademark OfficeThe present invention is directed to nanodiamond (ND) surface coatings and methods of making same. Such coatings are formed by a covalent linkage of ND crystals to a particular surface via linker species. The methods described herein overcome many of the limitations of the prior art in that they can be performed with standard wet chemistry (i.e., solution-based) methods, thereby permitting low temperature processing. Additionally, such coatings can potentially be applied on a large scale and for coating large areas of a variety of different substrates.Item Fluorinated nanodiamond as a precursor for solid substrate surface coating using wet chemistry(2010-12-28) Khabashesku, Valery N.; Liu, Yu; Halas, Nancy J.; Rice University; United States Patent and Trademark OfficeThe present invention is directed to nanodiamond (ND) surface coatings and methods of making same. Such coatings are formed by a covalent linkage of ND crystals to a particular surface via linker species. The methods described herein overcome many of the limitations of the prior art in that they can be performed with standard wet chemistry (i.e., solution-based) methods, thereby permitting low temperature processing. Additionally, such coatings can potentially be applied on a large scale and for coating large areas of a variety of different substrates.Item Fluorination of polymeric C.sub.60(2006-10-17) Margrave, John L.; Khabashesku, Valery N.; Gu, Zhenning; Davydov, Valery Aleksandrovich; Rakhmanina, Aleksandra Viktorovna; Kashevarova, Lyudmile Stepanovna; Rice University; United States Patent and Trademark OfficeThe present invention is directed towards the fluorination of polymeric C60 and towards the chemical and physical modifications of polymeric C60 that can be accomplished through fluorination.Item Functionalization of carbon nanomaterials for biomedical and nanocomposite applications(2010) Kuznetsov, Oleksandr; Khabashesku, Valery N.New derivatives of carbon nanostructures: nanotubes, nano-onions and nanocrystalline diamonds were obtained through fluorination and subsequent functionalization with sucrose. Chemically modified nanocarbons show high solubility in water, ethanol, DMF and can be used as biomaterials for medical applications. It was demonstrated that sucrose functionalized nanostructures can find applications in nanocomposites due to improved dispersion enabled by polyol functional groups. Additionally, pristine and chemically derivatized carbon nanotubes were studied as nanofillers in epoxy composites. Carbon nanotubes tailored with amino functionalities demonstrated better dispersion and crosslinking with epoxy polymer yielding improved tensile strength and elastic properties of nanocomposites.Item Functionalization of nanodiamond powder through fluorination and subsequent derivatization reactions(2010-10-26) Khabashesku, Valery N.; Liu, Yu; Margrave, John L.; Margrave, Mary Lou; Rice University; United States Patent and Trademark OfficeThe present invention is directed to functionalized nanoscale diamond powders, methods for making such powders, applications for using such powders, and articles of manufacture comprising such powders. Methods for making such functionalized nanodiamond powders generally comprise a fluorination of nanodiamond powder. In some embodiments, such methods comprise reacting fluorinated nanodiamond powder with a subsequent derivatization agent, such as a strong nucleophile.Item Magnetic Nanoparticles with Fe-N and Fe-C Cores and Carbon Shells Synthesized at High Pressures(MDPI, 2023) Bagramov, Rustem H.; Filonenko, Vladimir P.; Zibrov, Igor P.; Skryleva, Elena A.; Kulnitskiy, Boris A.; Blank, Vladimir D.; Khabashesku, Valery N.Nanoparticles of iron carbides and nitrides enclosed in graphite shells were obtained at 2 ÷ 8 GPa pressures and temperatures of around 800 °C from ferrocene and ferrocene–melamine mixture. The average core–shell particle size was below 60 nm. The graphite-like shells over the iron nitride cores were built of concentric graphene layers packed in a rhombohedral shape. It was found that at a pressure of 4 GPa and temperature of 800 °C, the stability of the nanoscale phases increases in a Fe7C3 > Fe3C > Fe3N1+x sequence and at 8 GPa in a Fe3C > Fe7C3 > Fe3N1+x sequence. At pressures of 2 ÷ 8 GPa and temperatures up to 1600 °C, iron nitride Fe3N1+x is more stable than iron carbides. At 8 GPa and 1600 °C, the average particle size of iron nitride increased to 0.5 ÷ 1 μm, while simultaneously formed free carbon particles had the shape of graphite discs with a size of 1 ÷ 2 μm. Structural refinement of the iron nitride using the Rietveld method gave the best result for the space group P6322. The refined composition of the samples obtained from a mixture of ferrocene and melamine at 8 GPa/800 °C corresponded to Fe3N1.208, and at 8 GPa/1650 °C to Fe3N1.259. The iron nitride core–shell nanoparticles exhibited magnetic behavior. Specific magnetization at 7.5 kOe of pure Fe3N1.208 was estimated to be 70 emu/g. Compared to other methods, the high-pressure method allows easy synthesis of the iron nitride cores inside pure carbon shells and control of the particle size. And in general, pressure is a good tool for modifying the phase and chemical composition of the iron-containing cores.Item Method for functionalizating carbon naontubes utilizing peroxides(2011-07-12) Khabashesku, Valery N.; Peng, Haiqing; Margrave, John L.; Margrave, Mary Lou; Billups, Edward W.; Ying, Yunming; Rice University; United States Patent and Trademark OfficeA method for functionalizing the wall of single-wall or multi-wall carbon nanotubes involves the use of acyl peroxides to generate carbon-centered free radicals. The method allows for the chemical attachment of a variety of functional groups to the wall or end cap of carbon nanotubes through covalent carbon bonds without destroying the wall or endcap structure of the nanotube. Carbon-centered radicals generated from acyl peroxides can have terminal functional groups that provide sites for further reaction with other compounds. Organic groups with terminal carboxylic acid functionality can be converted to an acyl chloride and further reacted with an amine to form an amide or with a diamine to form an amide with terminal amine. The reactive functional groups attached to the nanotubes provide improved solvent dispersibility and provide reaction sites for monomers for incorporation in polymer structures. The nanotubes can also be functionalized by generating free radicals from organic sulfoxides.Item Method for functionalizing carbon nanotubes utilizing peroxides(2006-10-24) Khabashesku, Valery N.; Peng, Haiqing; Margrave, Mary Lou; Billups, Edward W.; Ying, Yunming; Rice University; United States Patent and Trademark OfficeA method for functionalizing the wall of single-wall or multi-wall carbon nanotubes involves the use of acyl peroxides to generate carbon-centered free radicals. The method allows for the chemical attachment of a variety of functional groups to the wall or end cap of carbon nanotubes through covalent carbon bonds without destroying the wall or endcap structure of the nanotube. Carbon-centered radicals generated from acyl peroxides can have terminal functional groups that provide sites for further reaction with other compounds. Organic groups with terminal carboxylic acid functionality can be converted to an acyl chloride and further reacted with an amine to form an amide or with a diamine to form an amide with terminal amine. The reactive functional groups attached to the nanotubes provide improved solvent dispersibility and provide reaction sites for monomers for incorporation in polymer structures. The nanotubes can also be functionalized by generating free radicals from organic sulfoxides.Item Method for functionalizing carbon nanotubes utilizing peroxides(2010-06-22) Khabashesku, Valery N.; Peng, Haiqing; Margrave, John L.; Margrave, Mary Lou; Billups, Edward W.; Ying, Yunming; Rice University; United States Patent and Trademark OfficeA method for functionalizing the wall of single-wall or multi-wall carbon nanotubes involves the use of acyl peroxides to generate carbon-centered free radicals. The method allows for the chemical attachment of a variety of functional groups to the wall or end cap of carbon nanotubes through covalent carbon bonds without destroying the wall or endcap structure of the nanotube. Carbon-centered radicals generated from acyl peroxides can have terminal functional groups that provide sites for further reaction with other compounds. Organic groups with terminal carboxylic acid functionality can be converted to an acyl chloride and further reacted with an amine to form an amide or with a diamine to form an amide with terminal amine. The reactive functional groups attached to the nanotubes provide improved solvent dispersibility and provide reaction sites for monomers for incorporation in polymer structures. The nanotubes can also be functionalized by generating free radicals from organic sulfoxides.Item Method for preparation of new superhard B-C-N material and material made therefrom(2013-05-28) Khabashesku, Valery N.; Filonenko, Vladimir P.; Davydov, Valery Aleksandrovich; Rice University; United States Patent and Trademark OfficeAccording to some embodiments, a method of preparing a superhard material involves using mixtures of boron with carbon nitride of C3N4 stoichiometry as precursors. The C3N4 may be nanospherical. The result of chemical interaction of these components is the formation of new ternary compound B—C—N compound with a cubic structure. According to some embodiments, the composition is BCxN, where x is about 0.5. According to some embodiments, the composition is BCxN, where x is about 0.2. According to some embodiments, the compound has a unit cell parameter a=3.645±0.005 Å. According to some embodiments, the unit cell parameter a is about 3.655 Å. Synthesis is carried out under the conditions of thermodynamic stability of diamond at pressures higher that 6.0 GPa and temperatures above 1000° C. The starting components are taken according to the following ratio: boron—20-60 wt. %, C3N4—40-80 wt. %.Item Methods for preparing carbon nanotube/polymer composites using free radical precursors(2011-11-22) Khabashesku, Valery N.; Barrera, Enrique V.; Mcintosh, Daneesh; Peña-Paras, Laura; Rice University; United States Patent and Trademark OfficeIn some embodiments, the present invention is directed to methods of fully integrating CNTs and the surrounding polymer matrix in CNT/polymer composites. In some such embodiments, such integration comprises interfacial covalent bonding between the CNTs and the polymer matrix. In some such embodiments, such interfacial covalent bonding is provided by a free radical reaction initiated during processing. In some such embodiments, such free radical initiation can be provided by benzoyl peroxide. In some or other embodiments, the present invention is directed to CNT/polymer composite systems, wherein the CNTs within such systems are covalently integrated with the polymer. In some or other embodiments, the present invention is directed to articles of manufacture made from such CNT/polymer composite systems.Item Nanotube-amino acids and methods for preparing same(2012-01-10) Khabashesku, Valery N.; Peng, Haiqing; Margrave, John L.; Margrave, Mary Lou; Rice University; United States Patent and Trademark OfficeThe present invention is directed toward compositions comprising carbon nanotubes (CNTs) that are sidewall-functionalized with amino acid groups, and to amino acid compositions comprising carbon nanotubes. The present invention is also directed to simple and relatively inexpensive methods for the preparation of such compositions. Such compositions are expected to greatly extend the bio-medical applications of CNTs.