The work presented in my thesis has been concentrated on synthesis of novel nano structure particles and its application.
First, I have attempted to use new substituted PANI particles in ER suspensions. It is well known that ring substituents on the PANI backbone leads to a decrease in the conductivity. Thus the substituted PANI particles as synthesized may be used without further treatment of dedoping. Poly(2-Dodecyloxyaniline) (PDOA) was synthesized and used as particles for ER fluids. Synthesized polymer was soluble in organic solvent and showed good ER properties. The rheological properties of these ER fluids were measured by rotational rheometer equipped with a high- voltage generator.
Secondly, I synthesized styrene/4-hydroxystyrene block and gradient copolymers containing the organic dye Disperse Red 1 (S/HSDR) by nitroxide-mediated controlled radical polymerization, and a random copolymer was made by conventional free radical polymerization. Three different types of S/HSDR microspheres were used for a study of electrorheological (ER) behaviors, and each ER fluid system exhibited an enhancement of shear viscosity under application of an electric field, relative to the zero-field viscosity. The ER characterization as a function of controlled molecular structure in suspension showed different ER properties. In particular, suspension of S/HSDR gradient copolymer showed ER properties more enhanced than those of random or block copolymers with similar MW and copolymer composition.
Last, I demonstrate for the first time that compatibilization of an immiscible blend can be achieved via the addition of gradient copolymer during melt processing. By comparing several blend systems in terms of the evolution of the number-average dispersed phase diameter, Dn, of melt mixed samples after static annealing, I show that coarsening can be eliminated or suppressed upon melt mixing by addition of gradient copolymer to the blend.
