Zhengdong Cheng, Texas A&M University, Chemical Engineering Department, College Station, TX 77843, Tieying Gong, Artie McFerrin Department of Chemical Engineering, Texas A&M University, 200 Jack E Brown Building, College Station, TX 77843, Jingyi Shen, Artie McFerrin Department of Chemical Engineering, Texas A&M University, 409 Jack E Brown Building, Texas A&M University, College Station, TX 77843-3122, Zhibing Hu, University of North Texas, 211 Avenue A, Denton, TX 76203, and Manuel Marquez, Arizona State University; National Institute of Standards and Technology; Los Alamos National Laboratory.
Emulsion droplets containing gel particles of a thermo-responsive polymer, poly-N-isopropylacrylamide (PNIPAM), were used as an experimental model system for the study of nucleation. Using independent droplets, we can isolate the interactions between crystallites. Also, emulsion crystallization is proved to be capable of eliminating heterogeneous crystallization in atomic systems. Therefore, we are able to carry accurate measurements of the nucleation rate of colloidal crystals. Temperature was used to fine-tune the volume fraction of the PNIPAM suspensions. The droplet sizes were varied with flow rates in microfluidic emulsification to tune the nucleation volume. Measurements of UV-Vis spectroscopy, light scattering and polarized microscopy offer complimentary information of crystallization from reciprocal space (UV-Vis and light scattering) and real space (polarized microscopy).