title: The fabrication of single-walled carbon nanotube/polyelectrolyte multilayer composites by layer-by-layer assembly and magnetic field assisted alignment.
abstract: Single-walled carbon nanotube (SWNT)/polymer composites are widely studied because of their potential for high mechanical performance and multifunctional applications. In order to realize highly ordered multilayer nanostructures, we combined the layer-by-layer (LBL) assembly method with magnetic force-induced alignment to fabricate SWNT/poly(ethylamine) (PEI) multilayer composites. The SWNTs were functionalized with the anionic surfactant sodium dodecylbenzenesulfonate (NaDDBS) to realize negative charge at pH>7, while the PEI is positively charged at pH<7. The LBL method is based on the electrostatic absorption between the charged SWNTs and PEI resin to form multilayer composites on a solid substrate polydimethylsiloxane. Since the fabricated thickness of each SWNT-NaDDBS/PEI bilayer is uniform ( approximately 150 nm), the multilayer film thickness can be strictly controlled via the number of deposition cycles. A high magnetic field (8.5 Tesla) was used to align the SWNTs during the LBL process. The resultant LBL composite samples demonstrated high SWNT loading of approximately 50 wt% and uniform distribution of SWNTs in the multilayer structures, which was verified using a quartz crystal microbalance. Good alignment was also realized and observed through using high magnetic fields to align the nanotubes during the LBL deposition process. The results indicate that the LBL/magnetic alignment approach has potential for fabricating nanotube composites with highly ordered nanostructures for multifunctional materials and device applications.
authors.affiliation: High-Performance Materials Institute, Department of Industrial and Manufacturing Engineering, Florida State University, Tallahassee, FL 32310-6046, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tian
authors.forename: Jin Gyu
authors.initials: JG
authors.lastname: Park
authors.forename: Qunfeng
authors.initials: Q
authors.lastname: Cheng
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Liang
authors.forename: Chuck
authors.initials: C
authors.lastname: Zhang
authors.forename: Ben
authors.initials: B
authors.lastname: Wang