Synthesis and Crystallization of Anisotropic Polymer Colloids

74 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.Using seeded emulsion polymerization, methods are presented to synthesize polymer colloids with chemical and shape anisotropy. Two types of particles consisting of interpenetrating spheres, or dicolloids, are synthesized with length scales varying from approximately 300 nm to roughly 1.2 microm. For the first type of dicolloid, the seed and protrusion parts are coated with different surface groups such that the particles maybe given charge anisotropy by varying suspension pH. To obtain the second type of dicolloid, polystyrene seed spheres are swollen with N-isopropylacrylamide (NiPAM) to give particles with a polystyrene seed part and a poly NiPAM protrusion that can be made hydrophilic or hydrophobic depending on temperature. Evidence is given that chemical anisotropy has been developed for these particles. For future studies, methods are needed to more thoroughly characterize chemical anisotropy and particle interactions. Crystallization of shape anisotropic polymer colloids is investigated. Small differences in shape between the spherocylinders and dumbbells are found to result in significantly different crystallization behavior, with spherocylinders forming plastic crystals and orientationally ordered crystals in three dimensions, and dumbbells only ordering in two dimensions. However, it is more difficult to form colloidal crystals with both types of shape anisotropie particles than with spheres. Crystals of spherocylinders, in particular those with orientational order are observed to reflect more light than crystals of spheres, a trend that becomes more pronounced with increasing anisotropy.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD