Processing And Study Of Carbon Nanotube / Polymer Nanocomposites And Polymer Electrolyte Materials

The first part of the study deals with the preparation of carbon nanotube/polymer nanocomposite materials. The dispersion of multi-walled carbon nanotubes (MWNTs) using trifluoroacetic acid (TFA) as a co-solvent and its subsequent use in polymer nanocomposite fabrication is reported. The use of carbon nanotube/ polymer nanocomposite system for the fabrication of organic solar cells is also studied. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents. Our study demonstrates that MWNTs can be effectively purified and readily dispersed in a range of organic solvents including dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloromethane when mixed with 10 vol% trifluoroacetic acid (TFA). X-ray photoelectron spectroscopic analysis revealed that the chemical structure of the TFA-treated MWNTs remained intact without oxidation. The dispersed carbon nanotubes in TFA/THF solution were mixed with poly(methyl methacrylate) (PMMA) to fabricate polymer nanocomposites. A good dispersion of nanotubes in solution and in polymer matrices was observed and confirmed by SEM and optical microscopy study. Low percolation thresholds of electrical conductivity were observed from the fabricated MWNT/PMMA composite films. A carbon nanotube/ polymer nanocomposites system was also used for the fabrication of organic solar cells. A blend of single-wall carbon nanotubes (SWNTs) and poly3-hexylthiophene (P3HT) was used as the active layer in the device. The device characteristics showed that the fabrication of the solar cells was successful without any shorts in the circuit. The second part of the study deals with the preparation and characterization of electrode and electrolyte materials for lithium ion batteries. A system of lithium trifluoroacetate/ PMMA was used for its study as the electrolyte in lithium battery. A variety of different processing conditions were used to prepare the polymer electrolyte system. The conductivity of the electrolyte plays a critical role in the high power output of a battery. A high power output requires fast transport of lithium ions for which the conductivity of the electrolyte must be at least 3 x 10^-4 S/cm. Electrochemical Impedance Spectroscopy (EIS) was used to determine the conductivity of the polymer electrolyte films. Among the different processing conditions used to prepare the polymer electrolyte material, wet films of PMMA/salt system prepared by using 10vol% of TFA in THF showed the best results. At about 70wt% loading of the salt in the polymer, the conductivity obtained was about 1.1 x 10^-2 S/cm. Recently, the use of vanadium oxide material as intercalation host for lithium has gained widespread attention. Sol-gel derived vanadium oxide films were prepared and its use as a cathode material for lithium ion battery was studied. The application of carbon nanotubes in lithium ion battery was explored. A carbon nanotube /block copolymer (P3HT-b-PS) composite was prepared and its potential as an anode material was evaluated

Polymer Composites Having Highly Dispersed Carbon Nanotubes and Methods for Forming Same

A method of forming carbon nanotube-polymer composites includes the steps of forming a mixture solution including a plurality of carbon nanotubes dispersed in a co-solvent. The co-solvent includes an organic solvent and a second solvent being a short chain fluorinated carboxylic acid having a boiling point below 150 degrees C which is less oxidizing than nitric acid, and is soluble in both the organic solvent and water. The first polymer is mixed with the mixture solution to form a polymer including mixture. The co-solvent is removed from the polymer mixture to form a dispersed nanotube-polymer composite. The second solvent can be trifluoroacetic acid

Polymer Composites Having Highly Dispersed Carbon Nanotubes

A carbon nanotube-polymer composite includes a polymer continuous phase having at least a first polymer and a plurality of carbon nanotubes dispersed in the polymer continuous phase. The carbon nanotubes are non-functionalized nanotubes. The carbon nanotubes are between 0.05 and 40 weight % of the composite. At least 98% of the carbon nanotubes are not involved in nanotube bundles

Dispersion Of Carbon Nanotubes And Polymer Nanocomposite Fabrication Using Trifluoroacetic Acid As A Co-Solvent

We herein report the dispersion of multi-walled carbon nanotubes (MWCNTs) using trifluoroacetic acid (TFA) as a co-solvent. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents. Our study demonstrates that MWCNTs can be effectively purified and readily dispersed in a range of organic solvents including dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloromethane when mixed with 10 vol.% trifluoroacetic acid (TFA). X-ray photoelectron spectroscopic analysis revealed that the chemical structure of the TFA-treated MWCNTs remained intact without oxidation. The dispersed carbon nanotubes in TFA/THF solution were mixed with poly(methyl methacrylate) (PMMA) to fabricate polymer nanocomposites. A good dispersion of nanotubes in solution and in polymer matrices was observed and confirmed by SEM, optical microscopy, and light transmittance study. Low percolation thresholds of electrical conductivity were observed from the fabricated MWCNT/PMMA composite films. Further enhancement in the dispersion of MWCNTs was achieved by adding a conjugated conducting polymer, poly(3-hexylthiophene) (P3HT), to the dispersion, wherein TFA also serves as a doping agent to the conducting polymer. The ternary nanocomposite MWCNT/P3HT/PMMA exhibited an extremely low percolation threshold of less than 0.006 wt% of MWCNT content. This low percolation threshold is attributed to a good dispersion of MWCNTs and enhanced conductivity of the nanocomposites by conjugated conducting polymer. © IOP Publishing Ltd

Direct Laser Writing Of Microtunnels And Reservoirs On Nanocomposite Materials

A direct laser writing technique has been developed to create microtunnels and reservoirs on a nanocomposite material by utilizing the photon-thermal energy conversion property of gold nanoparticles. The absorption of photon energy and conversion to thermal energy by gold nanoparticles embedded in a polymer matrix caused polymer decomposition at the subsurface layer of the nanocomposite film, leading to the formation of covered microtunnels. Laser ablation/writing of polymer and doped-polymer materials has been widely used for the fabrication of microfluidic channels, optical devices and microelectromechanical systems (MEMS). Dye molecules with a strong absorption at certain wavelength ranges are often added to the polymers as photon-thermal energy converters to extend the range of polymers that may be processed by laser irradiation