Carbon nanotube/polymer composites and novel micro- and nano-structured electrospun polymer materials
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This research work focuses on single wall carbon nanotube (SWNT)/polymer composites and novel structured electrospun polymer materials. Poly (methyl methacrylate) (PMMA) is used as polymer matrix. Obtaining SWNT/PMMA composite with enhanced mechanical and electrical properties is one of the research goals. The first important step is to figure out a method for achieving uniform SWNT dispersion in PMMA. Eight different solvents were used to disperse SWNT in PMMA. It is found that the polar component of the solubility parameter (£_p) of the solvent affects SWNT dispersion in PMMA. SWNT dispersion in PMMA improves with increasing solvent Ôp value, and the most uniform dispersion is obtained in nitromethane, which is the most polar solvent employed in this study. SWNT/PMMA composite films at various SWNT concentrations were processed employing nitromethane as the solvent. Mechanical and electrical property enhancements are observed. Processing, structure, morphology, and properties of these composites are discussed. A comparison between reinforcement efficiency of SWNT, multiwall carbon nanotubes (MWNT), and vapor grown carbon nano fibers (VGCNF) in PMMA is also discussed. In order to electrospin SWNT/PMMA/nitromethane solution into composite nanofibers successfully, first PMMA was electrospun. With increasing solution concentration, morphology of the electrospun polymer changed from particles to fibers. At relatively low solution concentrations, micro- and nano-structured polymer particles, and at higher solution concentrations, porous and solid nanofibers are observed. SWNT/PMMA/nitromethane solution was electrospun into polymer shell-SWNT core nanofibers. Solvent characteristics play an important role on particle or fiber mat morphology. The qualitative relationship between solvent properties (evaporation rate, dielectric constant, surface tension, and viscosity) and particle morphologies is discussed. By tailoring solution properties and electrospinning conditions, one can produce particles or fibers with controlled morphology for specific applications.