Date of Award
Program or Major
Doctor of Philosophy
Donald C Sundberg
The primary purpose of this research was the morphological study of composite polymer (2 or more) nano-particles in an aqueous dispersed system. This included synthesis, characterization and mathematical/numerical modeling. For a composite latex particle, the morphology can play an important role in determining the final application properties, and the structure depends on many factors which are active during and after polymerization. Among these are the penetration of oligomeric chains into the latex particles, mixing of the two composite polymers, and eventual phase separation of such mixtures. These actions depend upon the materials used in the polymerization and the process by which the reaction is carried out.
This work involved both the common styrene/acrylic family of monomers as well as the newer polyurethane/acrylic hybrid system. The properties of the second stage polymers such as glass transition temperature, chain length and the polarity were studied and their impacts on the phase separation process were evaluated. For the polyurethane-acrylic hybrid latex system, the phase distribution of the two polymer components in these composite particles was characterized for the first time. Hydrogen bonding between the polymer chains was found to limit the diffusion of polymer chains and restrict phase separation towards the equilibrium morphology. A numerical model of the kinetics of the phase separation process applicable during and after polymerization was also developed. The Cahn-Hilliard theory was applied for this simulation to account for the new interfaces formed during phase separation.
Water interaction with polymer chains also became an important aspect of our study. Different states of water can exist simultaneously within a polymeric material, and the physical properties of the material will change depending upon these different states of water.
Jiang, Bo, "Morphological study of composite latex particles and water interaction with polymer chains" (2012). Doctoral Dissertations. 695.