Designing particle size of aminated polyacrylonitrile spheres to enhance electrorheological performances of their suspensions

The influence of particle size and functional group as one of the pivots for particle interaction that enhances electrorheological performance were studied by varying the particles to micron and nanometer-sized polyacrylonitrile (PAN) spheres for rheological comparability analysis. Emulsion polymerization and catalytic amination with diethylene triamine (DETA) were used to successfully synthesize ER particle samples and then dispersed in silicon oil for suspension analysis. Micron-sized particles presented a large surface electron density for high conversion of nitrile groups with DETA than in nano. Polar groups from DETA improved particle polarization which enhanced ER effect by increasing yield strength by more than 10 folds on raw PANs. However, small sized nano particle exhibited relatively reduced ER effect owing to aggregation by Brownian motion pronouncing aminated micro PAN with the best ER activity followed by the aminated nano PAN, micro PAN and nano PAN as follows.