Preceramic Polymer Routes to Amorphous and Crystalline Aluminosilicate Powders for Electrorheological Applications. I

Electrorheological (ER) fluids prepared using suspensions of amorphous and crystalline aluminosilicates in inert, nonpolar liquids are reported to exhibit good-to-exceptional ER activity.1–3 Unfortunately, the measured ER properties can vary greatly ever for compositionally similar fluids. This variation results, in part, because previous efforts to correlate ER behavior with the properties of well-defined aluminosilicates relied on commercially produced aluminosilicates. The commercial sources rarely provided a range of products (e.g. wide variety of compositions, particle sizes, etc.), or detailed quantification of powder properties (phase and chemical purity, surface area and pore size distribution, etc.). In addition, because the synthetic procedures are typically proprietary, it is not possible to identify important differences in methods of preparation. Hence, a detailed understanding of the exact mechanism(s) of ER activity as a function of individual aluminosilicate properties has been difficult-to-impossible to establish. The objectives of the work reported here are to: (1) develop a detailed and general synthetic approach to aluminosilicate powders; (2) develop protocols for characterizing their spectroscopic and physical properties, and (3) conduct preliminary ER studies to demonstrate the proof-of-principle of our chosen approach.