Synthesis and process optimization of colloidal unimolecular polymer, cup, particle formation, and its interfacial surface tension behavior
"Colloidal Unimolecular Polymer (CUP) particles are 3-9 nm size single-chain polymer nanoparticles that are made from amphiphilic acrylic co-polymers using the process of water reduction. The formation of CUP particles was driven by the polymer-polymer interactions being greater than polymer-solvent interactions as well as the charge-charge repulsion due to the increasing dielectric of the medium. CUPs provide a surfactant or additive-free nanoparticle system that was useful for studying the interfacial behavior of pure aqueous nanoparticles using a maximum bubble pressure tensiometer. The equilibrium surface tension shows a dependence on concentration and the charge density of the CUP particle. The equilibrium surface tension becomes constant at higher concentrations due to the counterion condensation effect. The dynamic surface tension is dominated by the rate of diffusion of CUP particles to the interface. The water reduction process which transforms a single polymer chain into a particle was observed using viscosity measurements on a vibration viscometer. Changing the hydrophobic and hydrophilic ratios in the co-polymer, changed the THF-water composition required to cause the collapse or self-organization of the polymer chain. The design of the CUP polymer was optimized by defining the charge density limits for stable and spheroidal CUP particle formation. It was found that the charge density (ions/nm²) of the particle must be between 0.32 to 0.85 to form a stable and spheroidal particle. When the Charge density (ions/nm²) is higher than 0.85, it would result in non-spheroid conformation (like dumbbell, pearl necklace, etc.) whereas when it is lower than 0.32, it would result in aggregation of the particles due to poor stability"--Abstract, page iv.
Chain collapse, Colloidal, dumbbell conformation, Hansen parameters, Single chain nanoparticles, Surface tension, Chemistry
Missouri University of Science and Technology
Networked Digital Library of Theses and Dissertations