1. Micro Wax Disks: Fabrication and Characterization
Zhengdong Cheng, Artie McFerrin Department of Chemical Engineering, Texas A&M University
Colloidal disks play an important role in petroleum engineering, cosmetic products and biological studies, but a plenty of space needs to fill in the colloidal disk studies. We proposed a systematic plan to explore the colloidal disk dispersions, including the production of uniform disk particles, and to characterize disk self-assembly and the rheological and hydrodynamic behaviors. We have successfully synthesized uniform microdisk particles using electrospray of -eicosene wax. Different aspect ratios and shapes have been obtained by tuning the synergetic effects of surfactants, and it is confirmed that the flat-disk structure originated from the layered structure of the rotator phase in low-temperature wax. A fluorescent confocal imaging technique has been developed to characterize the morphology of microdisks and their further assembling into columnar stacks showing evidence of crystalline packing at high concentration. Inorganic Zirconium Phosphate (a-ZrP) nanoplatelets are also studied as an important supplement for its potential to provide large aspect ratio (>100) platelets. Using analytical centrifugation, we have found a semi-dilute region in the sedimentation of ZrP and wax disk systems, which indicates an aspect ratio dependency in their hindrance functions. Based on these fulfillments, a series of studies have been launched, including:
* Self-assembling and phase transitions of colloidal disks
* Hydrodynamics of colloidal disks in microfluidics
* Interaction between colloidal disks ④ ① ② ③ ⑤
③: Columnar stacks of wax disks: bifrigent (up), fluorescent confocal (down). ④: Phase transitions in a-ZrP disk suspensions. ⑤: Flow behavior of a single disk in a microchannel.
①: Uniform wax emulsions via Electro-spray.
②: Disk morphology controlled by surfactants.