- 2:20 PM

Development of Nanostructured Composites Via Spin-Assisted Layer-by-Layer Assembly

Ming Qin1, Paul Podsiadlo1, and Nicholas A. Kotov2. (1) Chemical Engineering, University of Michigan, 2300 Hayward St., 3074 H.H. Dow Building,, Ann Arbor, MI 48105, (2) Chemical Engineering Department, Materials Science Department, Biomedical Engineering Department, University of Michigan, 2300 Hayward, Ann Arbor, MI 48109

Natural composites possess exceptional mechanical properties. Of these, hybrid organic/inorganic composites are in particular well recognized and studied thanks to their excellent combination of strengths, hardness, and toughness. Some of the well known examples of such natural materials are seashell nacre, teeth, and bones. Nacre, which is composed of alternating layers of biopolymers and CaCO3 plates, has been especially well studied as a model material for preparation strong, tough, and flaw-tolerant composites. The uniqueness of nacre lies in its composition and overall mechanical properties: in spite of being composed of nearly 95% of brittle inorganic material and a few percent of weak biopolymers, the composite is 2x as strong and more than 1000x as tough as either one of the phases taken separately. These properties have yet to be reproduced.

Multilayered polymer-platelet nanocomposites have shown the ability to mimic the structure and mechanical properties of nacre, and as such they attracted much scientific attention recently. They also offer a potential for generation of materials with much greater mechanical properties than nacre since the nanoscale building blocks possess much higher properties when compared to their more coarse counterparts. However, the controlling factors which need to be addressed first are dispersion of the reinforcing platelets, effective load transfer at the organic/inorganic interface, and structural control. The layer-by-layer assembly (LBL) appears to address these problems, however slow preparation speed of traditional dipping method of LBL greatly inhibits its further application. In this proposal we propose, to develop a rapid, controllable spinning-assisted LBL method. This method will reduce the production time several orders of magnitude and it will potentially promote the application of LBL assembly.