Partial Flattening of Amidine-functionalized Polystyrene Latex Particles
Open Access
- Author:
- Unal, Deniz B
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Darrell Velegol, Thesis Supervisor
Darrell Velegol, Thesis Honors Advisor
Themis Matsoukas, Faculty Reader
Andrew Zydney, Faculty Reader - Keywords:
- colloids
particle flattening
plasticizer - Abstract:
- One key step in selectively forming strong, flexible, and self-assembled chains of colloidal particles was particle flattening. A technique was developed to partially flatten spherical colloidal amidine-functionalized polystyrene latex particles of 2.5-3.3 μm diameter. The particles were electrostatically adhered to a substrate in an aqueous system. The spreading of the particles on the substrate was achieved by reducing the glass transition temperature below the room temperature. The glass transition temperature was lowered by absorbing a plasticizer, toluene, into the particles. The toluene was placed on top of a water layer 7 mm thick and was allowed to diffuse through to the particles resting on the substrate at the bottom of the layer. Fick’s 2nd Law and a sintering model derived in the literature were used to scale the toluene diffusion process. The flat sizes and shapes were confirmed and quantified by SEM imaging. The required toluene exposure time for a desired flat size was determined. The times required were 2 hrs 30 min, 3 hrs, and 3 hrs 30 min for particles with flat diameters 25%, 55%, and 90% of the particle diameters in that order.1 Process design parameters studied where toluene as a solvent, the absorption mechanism of particles to the substrate, and a siphoning system for quick and copious rinsing of toluene from the particles after toluene diffusion was completed. Crystalline silicon was found to be an appropriate substrate that did not leach ions into solution as was known to be the case with borosilicate glass.