(150c) INVITED: Amazing Properties of Lbl Assembled Nanocomposites
AIChE Annual Meeting
Monday, November 8, 2010 - 4:05pm to 4:30pm
Layer-by-layer assembly (LBL) is a new technique for design and manufacturing of composite materials based on sequential adsorption of nanometer scale layers of polymers and inorganic colloids. LBL is a universal method which provides unique uniformity and structural control to the resulting hybrid composites. This technique can resolve hard challenges of materials science related to mechanical, electrical, optical, and biological properties. In this presentation I will focus predominantly on mechanical property and charge transfer. Nanoscale building blocks are individually exceptionally strong. However that macroscale composites made from them are not. Assembly of a clay/polymer composite one nanoscale layer after another following the LBL technology with several very common polymers allowed us to prepare a homogeneous, optically transparent material with planar orientation of alumosilicate nanosheets. The stiffness and tensile strength of these multilayer composites are an order of magnitude greater than those for analogous nanocomposites made by traditional techniques. Stiffness and strength of such materials approach that of steel, while being made in a low-temperature process. The individual sheets were demonstrated to be consolidated in laminates. Engineering of polymers in atomic scale, LBL films in nanometer scale, and laminates in micro/mesoscale represents the multiscale hierarchical approach of composite design. Similar structural requirements of materials organization between nanoscale building blocks and matrix are also encountered in the design of electrical properties of the composites. Single walled carbon nanotubes exhibit exceptional conductivity at the level of individual tubes which is difficult to translate in the macroscopic world. Using LBL technology makes possible combining conductivity, transparency, and mechanical strength, which is critical for many key developments in electronics and energy applications today. LBL assembly with traditional polyelectrolytes resulted in coatings with electrical and optical characteristics comparable and competitive with much thicker and more brittle indium tin oxide layers traditionally used in industry. The same approach can also be used for the preparation of conductive fabrics and papers by impregnating them with carbon nanotubes in a cyclic process. The utilization of these materials as biosensors and energy storage devices will be discussed. Other applications as smart fabrics/papers, energy storage, and energy conversion will be discussed as well. Relevant References: P. Podsiadlo, E. M. Arruda, E. Kheng, A. M. Waas, J. Lee, K. Critchley, M. Qin, E. Chuang, A. K. Kaushik, H.-S. Kim, Y. Qi,_, S.-T. Noh, . N.A. Kotov, LBL Assembled Laminates with Hierarchical Organization from Nano- to Microscale: High-Toughness Nanomaterials and Deformation Imaging, ACS Nano, 2009, 3(6), 1564; Podsiadlo P., Kaushik A. K., Arruda E. M., Waas A. M., Shim B. S., Xu J., Nandivada H., Pumplin B. G., Lahann J., Ramamoorthy A., Kotov N. A., Ultrastrong and Stiff Layered Polymer Nanocomposites, Science, 2007,318, 80-83; Tang, Z.; Kotov, N. A.; Magonov, S.; Ozturk, B.; Nanostructured Artificial Nacre, Nature Materials, 2003, 2(6), 413?418; Mamedov, A. A.; Kotov, N. A.; Prato, M.; Guldi, D.; Wicksted, J. P.; Hirsch, A.; Molecular Design of Strong SWNT/Polyelectrolyte Multilayers Composites, Nature Materials, 2002, 1, 190?194.